JP7254645B2 - Double-sided polishing machine control system, control device, and substrate manufacturing method - Google Patents

Description

The present invention relates to a control system, a control device, and a substrate manufacturing method for a double-sided polishing apparatus for polishing the top surface and the BOT surface of a plate-shaped object to be polished.

As this type of control system, when polishing a layer to be processed formed on a semiconductor substrate, the friction between the layer to be processed and a surface plate holding an abrasive is measured during polishing, and the measured friction is The polishing speed of the layer to be processed is calculated based on the above, the calculated polishing speed is integrated over time to obtain the polishing amount, and polishing is terminated when the obtained polishing amount reaches a predetermined amount. (See Patent Document 1). This control system further integrates the amount of work done between the layer to be processed and the surface plate holding the abrasive, and terminates polishing when the amount of integrated work reaches a predetermined amount. . That is, this control system controls the polishing amount of the layer to be processed formed on the semiconductor substrate by managing the amount of work.

Let A be the relative speed at which the upper surface plate polishes the surface of the object to be polished, and B be the relative speed at which the lower surface plate polishes the back surface of the object to be polished, and the ratio of A to B (A/B) is 0.0. It is disclosed that the flatness of the object to be polished is improved by making it 6 or more and 0.8 or less (see Patent Document 2).

JP-A-11-265865 Japanese Patent No. 2993184

However, the control system described in Patent Literature 1 integrates the amount of work done between the layer to be processed and the surface plate holding the polishing agent, thereby calculating the polishing amount of the layer to be processed formed on the semiconductor substrate. is controlling Further, the control system described in Patent Document 1 polishes only one surface of a layer to be processed, not both the front and back surfaces of a semiconductor substrate, and controls the amount of polishing so as to be constant. It does not control the degree. If the control system described in Patent Document 1 is used to control the flatness of a substrate that requires both front and back surfaces to be polished, there is a problem that it becomes difficult to control the flatness.

Further, the control system described in Patent Document 2 improves the flatness of the object to be polished by controlling the relative velocity ratio (A/B) within a predetermined range. Not only is it primarily affected by the relative velocity, but it is also affected by other polishing conditions. For example, the flatness is affected by changes in the torque of the upper and lower surface plates and the processing time of the object to be polished. Therefore, there is a problem that the flatness of the object to be polished cannot be controlled with high accuracy only by controlling the relative speed ratio (A/B) within a predetermined range.

In addition, as the number of substrates mounted increases in order to increase the recording capacity, the demand for flatness quality has become even stronger. It is

SUMMARY OF THE INVENTION The present invention has been made to solve such problems. An object of the present invention is to provide a substrate manufacturing method.

(1) A control system for a double-side polishing apparatus according to the present invention rotates an object to be polished between an upper surface plate and a lower surface plate to rotate the upper surface plate and the lower surface plate, thereby removing the top surface of the object to be polished. In a control system for a double-sided polishing apparatus that polishes a surface and a BOT surface, a TOP surface work amount PT (Ws) required for polishing the TOP surface and a BOT surface work amount PB (Ws) required for polishing the BOT surface are determined. The polishing condition is controlled so that the work amount TB difference between the calculated TOP surface work amount PT and the BOT surface work amount PB is within a predetermined range.

(2) A control system for a double-side polishing apparatus according to the present invention is the control system for a double-side polishing apparatus according to (1), wherein the TOP surface workload PT and the BOT surface workload PB are controlled by the upper surface plate. and the rotation speed (rpm) and torque (Nm) of the lower surface plate and the processing time T (sec) of the object to be polished.

（式（１）中、Ｔ₁は仕事量の測定を開始する時間（ｓｅｃ）、Ｔ₂は仕事量の測定を終了する時間（ｓｅｃ）、ｋは定数、ＮＵは上定盤回転速度（ｒｐｍ）、ＮＣはキャリア公転速度（ｒｐｍ）、ＱＵは上定盤トルク（Ｎｍ）、ＱＵＭは上定盤メカロス分のトルク（Ｎｍ）、ｔはサンプリング時間（ｓｅｃ）をそれぞれ表す。）
により算出されることを特徴とする。 (3) A control system for a double-side polishing apparatus according to the present invention is the control system for a double-side polishing apparatus according to (1) or (2), wherein the TOP surface work PT required for polishing the TOP surface is: Formula (1) below

(In formula (1), T ₁ is the time to start measuring the work (sec), T ₂ is the time to finish measuring the work (sec), k is a constant, NU is the upper surface plate rotation speed (rpm ), NC is the carrier revolution speed (rpm), QU is the upper surface plate torque (Nm), QUM is the torque for the upper surface plate mechanical loss (Nm), and t is the sampling time (sec).)
It is characterized by being calculated by

（式（２）中、Ｔ₁は仕事量の測定を開始する時間（ｓｅｃ）、Ｔ₂は仕事量の測定を終了する時間（ｓｅｃ）、ｋは定数、ＮＬは下定盤回転速度（ｒｐｍ）、ＮＣはキャリア公転速度（ｒｐｍ）、ＱＬは下定盤トルク（Ｎｍ）、ＱＬＭは下定盤メカロス分のトルク（Ｎｍ）、ｔはサンプリング時間（ｓｅｃ）をそれぞれ表す。）
により算出されることを特徴とする。 (4) A control system for a double-side polishing apparatus according to the present invention is the control system for a double-side polishing apparatus according to any one of (1) to (3), wherein the BOT surface work required for polishing the BOT surface is PB is the following formula (2)

(In formula (2), T ₁ is the time to start measuring the work (sec), T ₂ is the time to finish measuring the work (sec), k is a constant, and NL is the lower surface plate rotation speed (rpm). , NC is the carrier revolution speed (rpm), QL is the lower surface plate torque (Nm), QLM is the lower surface plate mechanical loss torque (Nm), and t is the sampling time (sec).)
It is characterized by being calculated by

(5) A control system for a double-side polishing apparatus according to the present invention is the control system for a double-side polishing apparatus according to (1), wherein the predetermined range is determined by a flatness threshold value and a workload TB difference threshold value. It is characterized by being set.

(6) A control system for a double-side polishing apparatus according to the present invention is the control system for a double-side polishing apparatus described in (1), wherein the upper surface plate or the lower surface plate is selected based on the work load difference TB. It is characterized by controlling only one of them.

(7) The control device according to the present invention sandwiches the object to be polished between the upper surface plate and the lower surface plate, and rotates the upper surface plate and the lower surface plate to rotate the top surface and the BOT surface of the object to be polished. in a control device for a double-sided polishing apparatus for polishing a first calculating means for calculating a TOP surface work PT (Ws) required for polishing the TOP surface; and a BOT surface work PB (Ws) required for polishing the BOT surface and the difference between the TOP surface work amount PT calculated by the first calculation unit and the BOT surface work amount PB calculated by the second calculation unit is kept within a predetermined range. and a control means for controlling the polishing conditions as follows.

(8) A substrate manufacturing method according to the present invention is a substrate manufacturing method in which the TOP surface and the BOT surface of an object to be polished are polished by a double-sided polishing apparatus, wherein the TOP surface work required for polishing the TOP surface PT (Ws) is a first calculation step of calculating the BOT surface work amount PB (Ws) required for polishing the BOT surface; a second calculation step of calculating the BOT surface work amount PB (Ws) required for polishing the BOT surface; and a control step of controlling the polishing conditions so that the difference from the BOT surface work PB calculated in the second calculation step is within a predetermined range.

According to the control system for a double-side polishing apparatus according to the present invention described in (1) above, by controlling the polishing conditions, the flatness of the substrate can be quickly controlled with high accuracy, and a substrate with good flatness can be obtained.

According to the control system of the double-side polishing apparatus according to the present invention described in (2) above, the TOP surface work PT and the BOT surface work PB are calculated with high accuracy.

According to the control system of the double-side polishing apparatus according to the present invention described in (3) above, the TOP surface work amount PT required for polishing the TOP surface is calculated by Equation (1). In formula (1), machining time T (sec), constant k, upper surface plate rotation speed NU (rpm), carrier revolution speed NC (rpm), upper surface plate torque QU (Nm), upper surface plate mechanical loss Calculation processing is performed based on torque QUM (Nm) and sampling time t (sec). Since the processing for calculating the top surface work amount PT is a definite integral from the start to the end of the processing time, the calculation processing is performed during polishing of the substrate, and a highly accurate top surface work amount PT can be obtained.

According to the control system of the double-sided polishing apparatus according to the present invention described in (4) above, the BOT surface work PB required for polishing the BOT surface is calculated by the formula (2). In formula (2), machining time T (sec), constant k, lower surface plate rotation speed NL (rpm), carrier revolution speed NC (rpm), lower surface plate torque QL (Nm), lower surface plate mechanical loss torque QLM ( Nm) and the sampling time t (sec). Since the processing for calculating the BOT surface work PB is performed by definite integration from the start to the end of the processing time, the calculation processing is performed during polishing of the substrate, and a highly accurate BOT surface work PB can be obtained.

According to the control system of the double-sided polishing apparatus according to the present invention described in (5) above, the polishing amount of the substrate is kept within a predetermined range, and a substrate with good flatness can be obtained.

According to the control system of the double-side polishing apparatus according to the present invention described in (6) above, more rapid feedback control is performed, and substrates with good flatness are quickly manufactured.

According to the control device of the present invention described in (7) above, the first calculating means calculates the TOP surface work PT (Ws) required for polishing the TOP surface, and the second calculating means calculates the amount of work required for polishing the BOT surface. A required BOT surface work amount PB (Ws) is calculated. Further, the control means controls the polishing conditions so that the difference between the calculated TOP surface work amount PT and BOT surface work amount PB is within a predetermined range. As a result, by controlling the polishing conditions, the flatness of the substrate can be quickly controlled with high accuracy, and a substrate with good flatness can be obtained.

According to the substrate manufacturing method according to the present invention described in (8) above, the TOP surface work PT (Ws) required for polishing the TOP surface is calculated in the first calculation step, and the BOT surface work amount PT (Ws) required for polishing the TOP surface is calculated in the second calculation step. The BOT surface work PB (Ws) required for polishing is calculated, and the polishing conditions are controlled by the control process so that the difference between the TOP surface work PT and the BOT surface work PB is within a predetermined range. As a result, by controlling the polishing conditions, the flatness of the substrate can be quickly controlled with high accuracy, and a substrate with good flatness can be obtained.

According to the present invention, it is possible to provide a control system, a control device, and a substrate manufacturing method for a double-sided polishing apparatus, which can quickly control the flatness of a substrate with high accuracy by controlling the polishing conditions. Further, according to the present invention, substrates with good flatness can be stably produced.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure of the board|substrate manufactured by the control system of the double-sided polishing apparatus which concerns on embodiment of this invention, Fig.1 (a) shows the perspective view of a board|substrate, FIG.1(b) shows sectional drawing of a board|substrate. . It is a schematic diagram explaining the flatness of a substrate made of an aluminum substrate according to an embodiment of the present invention, FIG. 2(a) shows a state of zero flatness, and FIG. FIG. 2(c) is a graph showing the effect of plate thickness difference on flatness. 4A and 4B are views for explaining an example of a flatness calculation method; FIG. 1 is a configuration diagram of a control system for a double-sided polishing apparatus according to an embodiment of the present invention; FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining an example of the rotation direction of the double-side polishing apparatus which concerns on embodiment of this invention, Fig.5 (a) shows the rotation direction of an upper surface plate, FIG.5(b) shows a lower surface plate, a sun gear, and a Indicates the direction of rotation (revolution, rotation) of the carrier. 6A and 6B are graphs showing the flatness-workload TB difference threshold in the control system of the double-sided polishing apparatus according to the embodiment of the present invention, FIG. , shows the distribution during workload management. FIG. 7A is a diagram for explaining a flatness management method in the control system of the double-side polishing apparatus according to the embodiment of the present invention, FIG. shows a diagram of control by flatness in a batch-by-batch control system workload measuring instrument. 4 is a line graph showing the correlation between the amount of polishing and the amount of work in the control system of the double-sided polishing apparatus according to the embodiment of the present invention; 4 is a graph showing the relationship between the amount of double-side polishing and the amount of work for both-side polishing in the control system of the double-side polishing apparatus according to the embodiment of the present invention. 4 is a flowchart for explaining an example of processing from the start of polishing to the end of polishing in the control system of the intra-batch management method of the double-side polishing apparatus according to the embodiment of the present invention. FIG. 11A is a graph of the frequency distribution of the workload TB difference in the control system of the double-sided polishing apparatus according to the embodiment of the present invention, and FIG. , and FIG. 11(b) shows a graph during workload management. 4 is a normal distribution curve and a graph of the workload TB difference in the control system of the double-sided polishing apparatus according to the embodiment of the present invention; FIG. 13A is a graph of the frequency distribution of the flatness TB difference in the control system of the double-sided polishing apparatus according to the embodiment of the present invention, and FIG. , FIG. 13(b) shows a graph during workload management. 4 is a normal distribution curve and a graph of the flatness TB difference in the control system of the double-sided polishing apparatus according to the embodiment of the present invention;

A control system for a double-side polishing apparatus 10, a control device 20, and a method for manufacturing a substrate 30 according to an embodiment to which the control system for a double-side polishing apparatus according to the present invention is applied will be described with reference to the drawings.

First, the substrate 30 manufactured by the double-side polishing apparatus 10 according to the embodiment will be described. As shown in FIGS. 1(a) and 1(b), the substrate 30 has a disk shape with a thickness of th, an outer diameter of D, and an inner diameter of a central through hole h of d. In addition, the substrate 30 is not limited to a disk, and may have a shape other than a disk such as a square or an ellipse, and the through hole h in the center may not be provided. The substrate 30 is a hard disk substrate in this embodiment, but may be a substrate used for other purposes.

The substrate 30 has a thickness th of about 0.3 mm to 2 mm, an outer diameter D of about 30 mm to 270 mm, and an inner diameter d of about 10 mm to 70 mm. Specifically, thickness th is 1.75 mm, 1.6 mm, 1.27 mm, 1.0 mm, 0.8 mm, 0.635 mm, 0.6 mm, 0.5 mm, 0.38 mm, 0.3 mm, outer diameter The size of D is 3.5 inches, 2.8 inches, or 2.5 inches, and the inner diameter d has a disk shape selected from 20 mm and 25 mm.

The substrate 30 is composed of an aluminum base material made of a plate material of aluminum or an aluminum alloy. The substrate 30 has high-precision smoothness and surface hardness, and also has high rigidity and impact resistance that can suppress the occurrence of vibration due to high-speed rotation. In order to provide these characteristics, the substrate 30 is made of a hard material, and may be a glass substrate made of a glass plate.

As shown in FIG. 2(a), the substrate 30 is an aluminum base material (Al_Sub) which has undergone surface treatment such as grinder polishing and annealing. ing. Fig. 2(a) shows an ideal substrate in which the film thickness difference between the front and back surfaces of the electroless nickel-phosphorus plating, that is, the film thickness difference between the plating on the front surface and the plating on the back surface of the aluminum substrate (Al_Sub) is zero. is shown. An ideal substrate has the same compressive stress acting on the front surface side and the back surface side of the substrate, and has zero flatness. In this case, the aluminum substrate (Al_Sub) is a non-distorted substrate having a constant thickness and zero flatness.

On the other hand, FIG. 2(b) shows the actual substrate 30 in which a difference in plating film thickness is generated between the front and back sides by polishing the front and back sides. For example, before the substrate 30 is polished, the film thicknesses of the plating on the front side and the back side are the same, and the film thickness difference is zero. The plating may be thick and the plating on the back may be thin. In this case, the compressive stress acting on the front surface is large and the compressive stress acting on the back surface is small. Thus, if there is a difference in compressive stress between the front and back sides of the substrate 30, the flatness of the substrate 30 is deteriorated.

Further, as shown in FIG. 2(c), the rigidity of the substrate 30 decreases as the thickness of the aluminum base (Al_Sub) becomes thinner, and the compressive stress caused by the film thickness difference between the front and back surfaces of the electroless nickel-phosphorus plating coating decreases. be greatly affected. For example, when the thickness of the substrate 30 is 0.635 mm, the tilt angle of the slanted line representing the relationship between the film thickness difference between the front and back surfaces and the flatness is larger than when the thickness of the substrate 30 is 1.27 mm. As a result, the degree of deterioration of flatness increases.

The flatness in this embodiment means the magnitude of distortion with respect to the flatness of the substrate 30 . A substrate with high flatness indicates a substrate with large distortion (substrate with poor flatness), and a substrate with low flatness indicates a substrate with small distortion (substrate with good flatness). The magnitude of this distortion can be obtained from the distance from the flat surface to the surface of the substrate 30, the number of interference fringes, the polishing amount, and the like.

In the present invention, of the two surfaces of the substrate 30, the surface to be polished by the upper surface plate is defined as the TOP surface 30a, and the surface to be polished by the lower surface plate is defined as the BOT surface 30b. The degree of flatness can also be represented by a combination of the maximum unevenness difference on the TOP surface 30a side or the BOT surface 30b side of the substrate 30 and the code indicating the convex direction.

The flatness can be represented by the difference between the maximum values of the top surface 30a side and the BOT surface 30b side of the substrate 30, that is, the value of the TB difference calculated by TOP-BOT (top minus bottom). For example, if the TOP surface 30a side is convex, the calculation result is + (plus), and if the BOT surface 30b side is convex, the calculation result is - (minus), and the unit is μm.

An example of a specific flatness measurement method and calculation method will be described below with reference to FIG. FIG. 3 is a diagram for explaining flatness in this embodiment. The flatness of this embodiment is obtained by measuring the distance from a geometrically correct plane (geometrical plane) to the surface of the substrate 30 and using the measured numerical value to calculate the flatness.

Specifically, the difference (TOP) between the most projected portion and the most recessed portion in the thickness direction on the TOP surface 30a of the substrate 30, and the most projected portion in the thickness direction and the most recessed portion on the BOT surface 30b of the substrate 30. The difference in the thickness direction (BOT) from the recessed portion is measured, and is represented by a numerical value obtained by subtracting BOT from TOP.

For example, when the top surface 30a side is 3 μm and the BOT surface 30b side is 2 μm, the top surface 30a side is convex, and the calculation result is 3 μm−2 μm=+(plus) 1 μm. If the surface 30b side is 5 μm, the BOT surface 30b is convex, and the calculation result is 3 μm−5 μm=−(minus) 2 μm.

However, any calculation method may be used as long as it is possible to determine which side, the TOP surface 30a side or the BOT surface 30b side, is convex, and + and - may be reversed.

The definition of flatness is not limited to the above content, and for example, the same meaning as the flatness defined in the JIS standard (JIS B 0621-1984) may be used. The number of interference fringes and the amount of polishing may be measured, and the numerical value obtained by subtracting the numerical value of the BOT surface 30b from the numerical value of the TOP surface 30a may be expressed.

In order to measure both surfaces of the substrate 30, a flatness meter, a flatness measuring instrument, an interferometer, or the like can be selected according to the object to be detected. These measuring instruments may include not only a mechanism for measuring both sides of the substrate 30, but also a control device, a storage device, and an output device for calculating and displaying the measured values as predetermined values. The method of measuring flatness in this embodiment can be, for example, using a flatness meter.

Next, a control system for the double-side polishing apparatus 10 according to this embodiment will be described with reference to the drawings.
As shown in FIG. 4, the control system of the double-side polishing apparatus 10 includes the double-side polishing apparatus 10 and a control device 20 for controlling the double-side polishing apparatus 10. is configured to

The double-side polishing apparatus 10 includes an upper platen portion 11, a lower platen portion 12, an air pressure unit 13, a balancer 14, a polishing liquid supply unit 15, a load cell 16, and a torque sensor and a rotational speed sensor (not shown). ing. The double-sided polishing apparatus 10 sandwiches an object W to be polished between an upper surface plate portion 11 and a lower surface plate portion 12, and rotates the upper surface plate portion 11 and the lower surface plate portion 12 relative to the object W to be polished. Thus, both the front surface and the back surface of the object W to be polished are polished.

The upper surface plate portion 11 has an upper surface plate 21, a polishing pad 22, an upper surface plate driving motor 23, a rotating shaft 24, a rod 25, and a universal joint 26. The driving force of the upper surface plate drive motor 23 is transmitted to the upper surface plate 21 via the joint 26, and the upper surface plate 21 is rotated.

The upper surface plate 21 is made of a disk having a predetermined thickness, and the polishing pad 22 is detachably attached to the pad mounting portion 21a provided on the lower surface. configured to rotate. A plurality of rods 21b are provided on the upper surface of the upper surface plate 21, and are inserted into through-holes provided in the rods 25 with a slight gap therebetween. A rotation speed sensor (not shown) is connected to the upper surface plate 21, and the rotation speed of the upper surface plate 21 is converted into an electric signal and transmitted to the control device 20 connected thereto.

The polishing pad 22 polishes the surface of the substrate 30, and a known pad is used. The polishing pad 22 has a through hole formed in the central portion thereof, and is formed of a so-called doughnut-shaped disc. A plurality of through holes are formed at positions spaced inwardly from the outer periphery of the upper polishing pad, and polishing liquid is supplied to the polishing pad 22 and the substrate 30 positioned on the lower surface of the polishing pad 22 through the through holes. It's like

The upper surface plate driving motor 23 is attached to a stationary member (not shown) and is connected to the rotating shaft 24 via a pulley 23a such as a timing pulley and a belt 23b such as a timing belt. The driving force of the upper surface plate driving motor 23 is transmitted to the rotating shaft 24 via the pulley 23a and the belt 23b, and when the rotating shaft 24 is viewed from above, the rotating shaft 24 rotates clockwise and the upper surface plate 21 rotates. is also rotated clockwise.

A through-hole is formed in the rotation shaft 24 in the axial direction, and the rod 25 is inserted into the through-hole with a slight gap. A flange 24a is formed at the lower portion of the rotary shaft 24, and a plurality of rods 24b are provided on the flange 24a so as to protrude downward from the lower surface. A connecting portion (not shown) is formed on the upper portion of the rotating shaft 24, and the belt 23b of the upper platen driving motor 23 is connected to transmit the driving force from the belt 23b to the rotating shaft 24 via the connecting portion. It's like

The rod 25 has a shaft portion inserted into the through hole of the rotating shaft 24 , a flange portion formed below the shaft portion, and a connecting portion connected to the universal joint 26 . A connecting portion of the rod 25 is connected to the upper surface plate 21 via a universal joint 26 so that the pressure of the pneumatic unit 13 is transmitted to the upper surface plate 21 . A plurality of through-holes are formed in the flange portion of the rod 25, and the rod 21b of the upper surface plate 21 and the rod 24b of the rotary shaft 24 are inserted into each through-hole with a slight gap therebetween. ing.

Rotation of the rotating shaft 24 is transmitted to the rod 25 via the rod 24b. Further, the rotation of the rotary shaft 24 is transmitted to the upper surface plate 21 via the rods 24b and 21b.

The universal joint 26 is a universal joint in which the angle at which two members to be connected intersect each other can be freely changed. The connecting portion of the upper surface plate 21 and the rod 25 is connected to the universal joint 26, and the flange portion of the rod 25 is connected to the rotating shaft 24, so that the horizontal surface of the upper surface plate 21 and the rotating shaft 24 The horizontal surface of the upper platen 21 is kept horizontal by the universal joint 26 even if the angle of intersection with the axis changes. In addition, since the connecting portion of the lower surface plate 32 is fixed, it is possible to follow fluctuations of the lower surface plate during machining.

The lower surface plate portion 12 includes a table 31, a lower surface plate 32 rotatably attached to the table 31, a polishing pad 22, a plurality of carriers 33, a sun gear 34, and a lower surface plate driving motor 35 for rotating the lower surface plate 32. and a sun gear drive motor 36 that rotates the sun gear 34 .

The table 31 is a stationary member installed at a predetermined location, and supports the lower surface plate 32 so as to be rotatable. The table 31 has internal teeth 31t formed on its inner peripheral surface facing the outer peripheral surface of the polishing pad 22 mounted on the lower surface plate 32, and the external teeth 33t and the internal teeth 31t of the carrier 33, which will be described later, mesh with each other. It's like The table 31 also rotatably supports a shaft portion 32b of a lower surface plate 32, which will be described later.

The lower surface plate 32 has a horizontal upper surface and a truncated conical lower surface, and has a pad mounting portion 32a and a shaft portion 32b perpendicular to the pad mounting portion 32a. A through hole is formed in the shaft portion 32b so as to extend therethrough in the axial direction. A shaft portion 34b of the sun gear 34, which will be described later, is rotatably inserted into this through hole. A polishing pad 22 is detachably mounted on the upper surface of the pad mounting portion 32a of the lower surface plate 32, so that the lower surface plate 32 and the polishing pad 22 rotate together.

A rotation speed sensor (not shown) is connected to the lower surface plate 32, and the torque, torque fluctuation, and rotation speed of the lower surface plate 32 are converted into electric signals and transmitted to the control device 20 connected thereto. there is Although the torque of the lower surface plate 32 is calculated based on the current value of the lower surface plate drive motor 35, it may be the torque of the lower surface plate drive motor 35 during machining actually measured by a torque sensor.

The carrier 33 is formed of a disk having external teeth 33t. The external teeth 33t are configured to mesh with external teeth 34t of the sun gear 34 and internal teeth 31t of the table 31, which will be described later. The carrier 33 rotates and revolves around the sun gear 34 while meshing with the external teeth 34 t of the sun gear 34 and the internal teeth 31 t of the table 31 . The revolution speed of carrier 33 is calculated based on the rotation speed of sun gear 34 .

The carrier 33 is formed with an accommodating portion for accommodating a plurality of objects W to be polished, for example, about 3 to 5 objects W to be polished so that they can rotate. Also, the number of carriers 33 revolving around the sun gear 34 is about ten. Therefore, about 50 objects W to be polished are polished in one polishing step, and the number of objects W to be polished is sometimes treated as one batch.

The sun gear 34 has a gear portion 34a formed with external teeth 34t that mesh with the external teeth 33t of the plurality of carriers 33, and a shaft portion 34b. The shaft portion 34b is rotated counterclockwise when viewed from above the sun gear 34 by the sun gear drive motor 36, so that the sun gear 34 rotates counterclockwise.

The lower surface plate drive motor 35 is connected to the shaft portion 32b of the lower surface plate 32 via a pulley 35a such as a timing pulley and a belt 35b such as a timing belt. The driving force of the lower surface plate driving motor 35 is transmitted to the shaft portion 32b, and when the shaft portion 32b is viewed from above, the shaft portion 32b rotates counterclockwise. That is, the lower surface plate driving motor 35 rotates the lower surface plate 32 counterclockwise.

The sun gear drive motor 36 is connected to the shaft portion 34b of the sun gear 34 via a pulley 36a such as a timing pulley and a belt 36b such as a timing belt. The driving force of the sun gear drive motor 36 is transmitted to the shaft portion 34b, and when the shaft portion 34b is viewed from above, the shaft portion 34b rotates counterclockwise.

In the double-side polishing machine 10, as shown in FIG. 5A, the upper surface plate 21 rotates clockwise when the double-side polishing machine 10 is viewed from above. Further, as shown in FIG. 5B, the lower surface plate 32 rotates counterclockwise, the carrier 33 rotates clockwise while revolving counterclockwise around the sun gear 34, and the sun gear 34 rotates counterclockwise. rotate to The rotation speed of the sun gear 34 is detected by a rotation speed sensor. Note that the rotation direction of the sun gear 34 may be counterclockwise. In this case, the direction of rotation of the carrier 33 is reversed.

As shown in FIG. 4, the pneumatic unit 13 is composed of a double-acting rod cylinder that reciprocates up and down, and has a piston 13a, a cylinder body 13b, and a piston rod 13c. The piston rod 13 c is connected to the rod 25 of the upper platen portion 11 and has a structure that moves the upper platen 21 up and down via the rod 25 and the universal joint 26 .

The balancer 14 has a balance cylinder 14a, a piston 14b, a wire 14c, and pulleys 14d and 14e for guiding the wire 14c. One end of the wire 14c is connected to the piston 14b, and the other end is connected to the upper surface plate portion 11. As shown in FIG. The balancer 14 maintains balance by supporting the weight of the upper surface plate portion 11 when the upper surface plate 21 is lifted and lowered by the pneumatic unit 13, and reduces the load required for the lifting operation of the upper surface plate 21 by the pneumatic unit 13. At the same time, it functions so as to assist the elevation of the upper platen 21 with high precision and speed.

The polishing liquid supply unit 15 has a pump 15a, a pressure gauge 15b, and an open/close valve 15c. It is configured to supply the pad 22 and the object W to be polished. The pump 15a is connected to the control device 20, and its operation is controlled by the control device 20. As shown in FIG. The pressure gauge 15b is connected to the control device 20, and the signal of the pressure (MPa) of the pump 15a is transmitted to the control device 20.

The slurry consists of a liquid polishing liquid containing abrasive grains consisting of aluminum oxide (Al ₂ O ₃ ) and silicon oxide (SiO ₂ ) and chemical components consisting of etching components. The slurry is structured so that the surface chemical action of the abrasive grains or the action of the chemical components increase the mechanical polishing effect due to the relative movement between the slurry and the object W to be polished, and a smooth polished surface can be obtained. ing.

The load cell 16 consists of a sensor that detects forces such as load and torque, and is provided on the rod 25 to detect the load and load fluctuations of the rod 25, the torque and torque fluctuations, and the upper surface plate 21 connected to the rod 25. The applied load, load fluctuations, torque, and torque fluctuations are converted into electric signals and transmitted to the control device 20 to which it is connected.

Next, the control device 20 according to this embodiment will be described with reference to the drawings.
The control device 20 has a central processing unit that performs arithmetic processing and a memory that stores a control program, and includes first calculation means, second calculation means, and control means (not shown). The controller 20 is connected to the polishing liquid supply unit 15, the pneumatic unit 13, the upper platen drive motor 23, the lower platen drive motor 35 and the sun gear drive motor 36, and controls the operation of each component.

The control device 20 controls the amount of work PT (Ws) required for polishing the TOP surface 30a of the object W to be polished,
The amount of work PB (Ws) required for polishing the BOT surface 30b of the object W to be polished is calculated, and the polishing conditions are controlled so that the difference between the calculated amount of work PT and the amount of work PB is within a predetermined range. do. Specifically, the control device 20 controls the polishing conditions of the double-sided polishing apparatus 10 to quickly control the flatness of the substrate 30, and the double-sided polishing apparatus 10 manufactures the substrate 30 with good flatness. .

The first calculation means calculates the TOP surface work PT (Ws) required for polishing the TOP surface 30a of the object W to be polished shown in FIG. The first calculation means calculates the top surface work PT based on the upper surface plate rotation speed (rpm) and upper surface plate torque (Nm) of the upper surface plate 21 and the processing time T (sec) of the object W to be polished. do.

The amount of work (Ws) is the amount of energy (J) used for polishing the object W to be polished, and is calculated by the following formula: amount of work (Ws) = rotation speed (rpm) x torque (Nm) x processing time (sec). be.

Specifically, the first calculation means calculates the TOP surface work PT based on the following formula (1).

In formula (1), T ₁ is the time to start measuring the work (sec), T ₂ is the time to finish measuring the work (sec), k is a constant, and NU is the upper surface plate rotation speed ( rpm), NC is the carrier revolution speed (rpm), QU is the upper platen torque (Nm), QUM is the upper platen mechanical loss torque (Nm), and t is the sampling time (sec).

The machining time T represents a predetermined elapsed machining time, that is, the machining time for measuring the amount of work. In other words, it represents that the work is measured between T ₁ and T ₂ in equation (1), T ₁ is the time to start measuring the work, and T ₂ is the end of the work measurement. represents the time to

T ₁ and T ₂ may be determined according to the interval for measuring the amount of work, it is preferable to use the measurement start time or the previous sampling end time for T ₁ , and the measurement end time or this time for T ₂ Preferably, the sampling end time is used.

T ₁ and T ₂ can be changed as appropriate. For example, in the case of batch-by-batch management, the measurement start time can be used for T ₁ and the measurement end time can be used for T ₂ . When measuring the work for 10 minutes from the start to the end of polishing of a given batch, T ₁ is the work measurement start time of the given batch, 0, and T ₂ is the work measurement end time of the given batch ( For example, the work amount can be calculated using 600 (sec) of the polishing end time).

In addition, the amount of work can also be calculated based on a predetermined sampling time. For example, when the work load measurement interval in a predetermined batch is every 10 seconds, in the first sampling, the measurement start time of 0 is used for _T1 , and the current sampling end time of 10 (sec) is used for _T2 . , in the second sampling, the measurement start _time of 0 is used for _T1 , and the current sampling end time of 20 (sec) is used for _T2 . , the amount of work can be calculated by accumulating the sampling time.

Also, when measuring the work amount without accumulating the sampling time, for example, T ₁ is the last sampling end time of 10 (sec), and T ₂ is the current sampling end time of 20 (sec). Therefore, it is possible to calculate by changing the numerical values of _T1 and _T2 each time the timing of sampling changes. Note that T ₁ and T ₂ in equation (1) and equation (2) described later must be the same.

The upper surface plate rotation speed NU in the formula (1) is the rotation speed of the upper surface plate 21 detected by the rotation speed sensor provided on the upper surface plate 21, and the carrier revolution speed NC is the rotation speed of the sun gear 34. The revolution speed of the carrier 33 is calculated from the rotation speed of the sun gear 34 detected by the sensor, and the upper surface plate torque QU is the torque of the upper surface plate 21 detected by the load cell 16 .

In addition, the upper surface plate mechanical loss QUM (Nm) in the equation (1) represents the torque loss lost due to the rotation of the upper surface plate 21 itself, and the upper surface plate mechanical loss QUM is, for example, a load applied to the upper surface plate 21. It is obtained by detecting in advance the torque of the upper surface plate 21 when the upper surface plate 21 is idly rotated without applying.

The second calculator is configured to calculate the BOT surface work PB (Ws) required for polishing the BOT surface 30b of the object W to be polished shown in FIG. The second calculation means calculates the BOT surface work PB based on the lower surface plate rotation speed (rpm) and lower surface plate torque (Nm) of the lower surface plate 32 and the processing time T (sec) of the object W to be polished.

Specifically, the second calculation means calculates the BOT surface work PB based on the following equation (2).

In equation (2), T ₁ is the time to start measuring the work (sec), T ₂ is the time to finish measuring the work (sec), k is a constant, and NL is the lower surface plate rotation speed (rpm ), NC is the carrier revolution speed (rpm), QL is the lower surface plate torque (Nm), QLM is the lower surface plate mechanical loss torque (Nm), and t is the sampling time (sec).

The lower surface plate rotation speed NL and the lower surface plate torque QL in the equation (2) are based on the rotation speed of the lower surface plate 32 detected by a rotation speed sensor provided on the lower surface plate 32 and the current value of the lower surface plate drive motor 35. The carrier revolution speed NC is the revolution speed of the carrier 33 calculated from the rotation speed of the sun gear 34 detected by the rotation speed sensor of the sun gear 34 .

In addition, the lower surface plate mechanical loss QLM (Nm) in the formula (2) represents the torque loss lost due to the rotation of the lower surface plate 32 itself. It is obtained by detecting in advance the torque of the lower surface plate 32 when the lower surface plate 32 is idled.

The sampling time t (sec) in equations (1) and (2) refers to the time interval at which samples are taken during the polishing time of the processing time T. As shown in FIG. For example, if the sampling time t is 1 sec, data such as torque and rotation speed at that moment are detected every 1 sec, and based on the detected data, the top surface work at the sampling time of 1 sec is calculated by equation (1). The amount PT (Ws) is calculated, and the BOT surface work PB (Ws) at the sampling time of 1 sec is calculated by Equation (2).

Equation (1) is the work (Ws) obtained by definite integration from T ₁ (sec) to T ₂ (sec) of the TOP surface work PT at a sampling time of 1 sec. Similarly to Equation (1), Equation (2) is the work (Ws) obtained by definite integration from T ₁ (sec) to T ₂ (sec) of the BOT surface work PB at the sampling time of 1 sec.

The sampling time t and the processing time T in the formulas (1) and (2) depend on setting parameters such as the structure, size, material, and shape of the object to be polished W, the structure and size of the double-sided polishing apparatus 10, and the polishing pad. and the type of polishing liquid, and data such as experimental values. In addition, the constant k in formulas (1) and (2) is a numerical value for converting the rotational speed (rpm) and torque (Nm) of the upper surface plate or lower surface plate into work (Ws). can be obtained using a conversion formula.

The control means adjusts the polishing conditions so that the flatness of the substrate 30 falls within the predetermined flatness range by keeping the difference between the calculated TOP surface work amount PT and BOT surface work amount PB within a predetermined range. Control. In other words, the polishing conditions are controlled so that the work amount TB difference between the TOP surface work amount PT and the BOT surface work amount PB falls within a predetermined range of the target work amount TB difference. The flatness can be kept within a predetermined flatness range.

Based on the work amount TB difference, that is, the difference between the TOP surface work amount PT calculated by the first calculation means and the BOT surface work amount PB calculated by the second calculation means, the upper surface plate 21 or It is configured to control only one of the lower surface plates 32 . By controlling the upper surface plate 21 or the lower surface plate 32, high-precision and rapid control is performed.

Polishing conditions to be controlled include rotation speed (rpm), load (kg), number of revolutions of carrier (rpm), time (sec), flow rate of polishing liquid (mL/min), etc., and are controlled by a surface plate. When performing, it is preferable to control the rotation speed, the load, the number of revolutions of the carrier, or a combination thereof, and from the viewpoint of easy control, it is more preferable to control the rotation speed and / or the load. , it is even more preferable to control only the rotational speed.

The predetermined range is set by a flatness threshold and a workload TB difference threshold, as shown in FIG. 6(a). As a procedure for setting the predetermined range, first, the range of flatness allowed for the object W to be polished (the range between the upper limit threshold value and the lower limit threshold value of flatness) is determined. Next, the threshold value of the work amount TB difference allowed for the object W to be polished is determined. The threshold value of the workload TB difference can be determined, for example, by previously performing separate polishing.

The work load difference TB can be represented by S=PT-PB, and either the upper surface plate 21 or the lower surface plate 32 is controlled by the control means so that S falls within a predetermined range. It should be noted that the control is preferably performed by management for each batch or management within a batch. In batch-by-batch management, control is performed each time one batch is completed, and in intra-batch management, control is performed within a batch, that is, during polishing. A batch represents a unit of the number of objects W to be polished in one polishing process, and one batch is about 50 objects W to be polished, although not limited to this.

The target work TB difference is the shaded rectangular area bounded by the determined flatness threshold and the work TB difference threshold. The workload TB difference threshold is a region in which objects can be created that do not protrude from the flatness threshold.

In FIG. 6(a), the horizontal axis is the workload TB difference (kWs), and the vertical axis is the flatness (μm). , is a graph plotted with black dots.

FIG. 6(b) is a graph similar to FIG. 6(a), in which the horizontal axis represents the work load TB difference (kWs) and the vertical axis represents the flatness (μm). is a graph in which the flatness (μm) at the time of workload control is plotted with black dots. As shown in FIG. 6(b), when managing the amount of work, that is, by controlling the amount of work, the flatness can be controlled. can be accommodated within the area of

The flatness threshold, work load TB difference threshold, and target work load TB difference are determined by setting parameters such as the structure, size, material, and shape of the object W to be polished and the structure and size of the double-sided polishing apparatus 10, and experimental values. It is appropriately selected based on the data. The flatness threshold, workload TB difference threshold, and target workload TB difference are determined, for example, by performing test polishing each time any of the manufacturing equipment (manufacturing line), polishing pad, polishing liquid, and flow rate of the polishing liquid changes. be done.

Next, normal production and workload management will be described with reference to the drawings.
In the conventional normal production where work volume management is not performed, as shown in FIG. Flatness is measured. The measurement result is displayed on the flatness meter as a flatness TB difference, for example, as a graph.

Then, when it is determined that the flatness TB difference exceeds the upper limit, it is found that the plating thickness of the object W to be polished satisfies TOP>BOT, and the TOP relative speed UP is set. That is, the rotational speed of the upper surface plate 21 is set to be relatively faster than that of the lower surface plate 32 . On the other hand, when it is determined from the flatness TB difference graph that the flatness TB difference exceeds the lower limit, it is found that the plating thickness of the object W to be polished satisfies TOP<BOT, and the BOT relative speed UP is set. be done. That is, setting is made such that the rotation speed of the lower surface plate 32 is relatively faster than that of the upper surface plate 21 . These determinations and settings are made by the operator.

Therefore, during normal production without workload management, the TOP relative speed UP and the BOT relative speed UP are set after the surface inspection so that the flatness of the object W to be polished is appropriate. 10 is adjusted. Therefore, the control time lag took a long time, and the control was sometimes performed after several batches had passed.

On the other hand, at the time of workload management in this embodiment, as shown in FIG. Since it is calculated, the control time lag can be greatly shortened, and highly accurate flatness can be achieved. In addition, the control that waits until the flatness measurement result is obtained is not necessary, and the manufacturing cost can be greatly reduced.

Next, the correlation coefficient between the amount of work (kWs) of the object W to be polished and the amount of polishing (mg) of the object W to be polished will be described with reference to the drawings. The polishing amount (mg) per one object W to be polished is the total weight (mg) of the objects W to be polished for one batch of 50 objects W to be polished and the total weight (mg) of the objects W to be polished before polishing of 50 objects W It can be obtained by subtracting the total weight (mg) of the object to be polished W after polishing for one batch of sheets and dividing the subtracted total weight by 50 sheets.

In FIG. 8, the batch number is plotted on the horizontal axis, and the range from batch 1 to batch 18 is shown. The pad time, ie, the pad usage time until the first batch was polished, was about 25 hours. The vertical axis on the left side of FIG. 8 indicates the amount of work (kWs), and the vertical axis on the right side indicates the amount of polishing (mg). FIG. 8 shows a line graph showing the relationship between each batch and the amount of work, and a line graph showing the relationship between each batch and the polishing amount.

Specifically, the amount of double-sided polishing for each batch is represented by a solid polygonal line, the double-sided work amount for each batch is represented by a fine broken polygonal line, and the BOT workload for each batch is represented by a dashed-dotted polygonal line, The TOP work for each batch is represented by the rough dashed polygonal line. The double-sided work amount is the sum of the work amount for the TOP surface and the work amount for the BOT surface.

According to the graph of FIG. 8, the amount of double-side polishing represented by the solid polygonal line and the amount of double-side polishing represented by the fine broken polygonal line are similar. It can be seen that there is a correlation between the lines of . In addition, the graph shows that the BOT work amount represented by the dashed-dotted line and the TOP work amount represented by the rough broken line line are similar, and it can be seen that there is a correlation between the two. Although the four line graphs have different numerical values, the shapes of the lines are similar. It can be seen that the workloads are correlated with each other.

As a result of verifying the polishing amount-work load correlation shown in FIG. 8, the correlation between the polishing amount of the object W to be polished and the double-sided work amount of the object W to be polished is also represented by the graph of FIG. FIG. 9 is a graph in which the horizontal axis is double-sided work (kWs) and the vertical axis is double-sided polishing amount (mg), and the double-sided polishing amount (mg) against the calculated double-sided work is plotted with black dots. .

The double-side polishing amount-double-side work amount graph shown in FIG. 9 is a graph in which the double-side polishing amount (mg) is plotted with black dots against the double-side work amount (kWs) at a standard deviation σ of 2.4. The plotted black dots are concentrated near the dashed sloping line, and it can be seen that there is a correlation between the double-side work (kWs) and the double-side polishing amount (mg), which is in a proportional relationship.

Note that the dashed slope line is represented by an approximation formula, y=0.1346x-2.2355, which is a regression equation, as shown in the upper right of FIG. Also, R ² =0.9592 represents the coefficient of determination when the approximation formula is handled in Excel. This coefficient of determination is a value that expresses the degree of fit of the estimated regression formula to the data. mean difference) and dividing the regression variation by the total variation, which is the square of the correlation coefficient. Also from this regression equation, it can be seen that the polishing amount of the object W to be polished can be controlled by controlling the amount of work for polishing the object W to be polished.

Since there is a correlation between the amount of polishing of the object W to be polished and the amount of work on both sides of the object W to be polished, the amount of work on the top surface and the amount of work on the BOT surface of the object W are used to determine the amount of work on the object to be polished. It is possible to estimate the amount of double-side polishing for one W sheet. Similarly, since the plating thickness has a correlation with the flatness, by controlling the work amount of the TOP surface and the work amount of the BOT surface (= polishing amount = plating thickness), the polishing amount of the TOP surface and the BOT surface can be controlled, and in turn, the flatness can be controlled, and the yield in the production of the substrate 30 can be improved even if the object W to be polished is a thin substrate.

The amount of work is calculated for each of the TOP surface and the BOT surface. Each of the TOP surface and BOT surface of is not individually measured, and the polishing amount of both surfaces of one sheet is obtained.

Next, a method for manufacturing the substrate 30 according to the embodiment will be described with reference to the drawings.

The method for manufacturing the substrate 30 according to the embodiment includes an aluminum blank manufacturing process, a lathe processing process, an annealing process, a grinder grinding process, an annealing process, an electroless nickel-phosphorus plating (Ni-P) process, an annealing process, a polishing process, a flat It includes a degree control process, a surface inspection process, a flatness measurement process, and a shipping process. Each process is performed in order, and the substrate 30 is manufactured through each process.

Among the steps of the method for manufacturing the substrate 30 according to the embodiment, each step other than the polishing step and the flatness control step is composed of known steps. will be described with reference to

In the polishing step, fifty pieces of one batch of objects W to be polished are set on the carrier 33 shown in FIG. When the setting of the object W to be polished is completed, the double-sided polishing apparatus 10 is operated under the set polishing conditions to start polishing. When the double-side polishing apparatus 10 is operated, as shown in FIGS. 5(a) and 5(b), the upper surface plate 21 rotates clockwise, and the lower surface plate 32, carrier 33 and sun gear 34 rotate counterclockwise. rotate to Due to this rotation, the object to be polished W set on the carrier 33 revolves and rotates within the carrier. Note that the sun gear 34 may rotate clockwise. In this case, the rotation direction of the carrier 33 is clockwise.

At the same time as the polishing is started, the polishing liquid is supplied to the object W to be polished from the polishing liquid supply pressure unit 15 . The object to be polished W is polished by the polishing pad 22 mounted on the pad mounting portion 21a of the upper surface plate 21, the polishing pad 22 mounted on the pad mounting portion 32a of the lower surface plate 32, and the supplied polishing liquid. The TOP surface 30a and the BOT surface 30b of body W are polished simultaneously.

As shown in FIG. 10, the flatness control process in the in-batch management includes upper surface plate work amount measurement (step S1), upper surface plate work amount calculation (first calculation step; step S2), and rotation speed calculation. (Step S3), lower surface plate workload measurement (step S4), lower surface plate workload calculation (second calculation step; step S5), lower surface plate rotation speed setting (step S6), set machining time determination (step S7).

The flatness control process from step S1 to step S7 is performed by the control device 20 while the object W to be polished is being polished. The upper surface plate work amount measurement (step S1) and the lower surface plate work amount measurement (step S4) are performed simultaneously, but they may be performed in order, and if they are performed in order, whichever is performed first good.

Further, although the rotation speed of the lower surface plate 32 is set in the lower surface plate rotation speed setting (step S6), the rotation speed of the upper surface plate 21 may be set instead. Further, the flatness control process can be controlled by changing the polishing conditions of the upper surface plate 21 or the lower surface plate 32 . Although FIG. 10 shows only the case where the rotation speed is set and controlled, the flatness accuracy can be further improved by controlling the load applied to the object W to be polished. In this case, it is possible to suppress the occurrence of quality differences in the substrate 30 due to pad use time differences. Also, if the flow rate adjustment of the polishing liquid supplied by the polishing liquid supply unit 15 can be automated, more stable polishing control becomes possible.

In the upper surface plate work amount measurement (step S1), the work amount of the upper surface plate 21 is measured based on the upper surface plate torque, that is, Σ (relative speed × surface plate torque), and the upper surface plate work amount is calculated. In (step S2), the work amount of the upper surface plate 21 is calculated using the aforementioned formula (1) based on the measurement data measured by the upper surface plate work amount measurement (step S1). The calculation takes into account the control time lag and pad elapsed time. In addition, the upper surface plate work amount calculation (step S2) corresponds to the first calculation step according to the present invention.

In the rotational speed calculation (step S3), first, a value obtained by subtracting the target work amount TB difference converted to the elapsed time from the target work amount TB difference at the time of completion of machining from the TOP work amount in the machining elapsed time is calculated. It is calculated as the target work amount of the BOT in the elapsed time. It should be noted that the TOP work amount is obtained by Equation (1) for calculating the TOP surface work amount PT. The target workload TB difference at the completion of processing is determined based on the flatness threshold and the workload TB difference threshold, as shown in FIG. 6(a).

Next, from the obtained target work amount of BOT, measured torque of BOT, and time, the relative speed of BOT is calculated by the following formula.
Target work amount of BOT÷Actual torque of BOT÷Time=Relative speed of BOT The relative speed of BOT is obtained from the above formula.

Next, from the obtained relative speed of the BOT and the revolution speed of the carrier 33, the rotation speed of the lower surface plate 32 to be controlled is calculated by the following formula.
Relative speed of BOT+Revolution speed of carrier 33=Rotational speed of lower surface plate 32 to be controlled In addition, instead of the rotational speed of lower surface plate 32, the rotational speed of upper surface plate 21 may be obtained. and the revolution speed of the carrier 33, the rotation speed of the upper surface plate to be set in the next step is calculated by the following formula.
Relative speed of TOP−Revolution speed of carrier 33=Rotational speed of upper surface plate 21 to be controlled According to the above equation, the rotational speed of lower surface plate 32 or upper surface plate 21 is set in step S6.

In the lower surface plate work amount measurement (step S4), the work amount of the lower surface plate 32 is measured based on the lower surface plate torque, that is, Σ (relative speed x surface plate torque), and the lower surface plate work amount is calculated (step S5). In , the work amount of the lower surface plate 32 is calculated using the aforementioned formula (2) based on the measurement data measured by the lower surface plate work amount measurement (step S4). The calculation takes into account the control time lag and pad elapsed time. It should be noted that the lower surface plate work amount calculation (step S5) corresponds to the second calculation step according to the present invention.

In the lower surface plate rotation speed setting (step S6), the rotation speed of the lower surface plate 32 to be controlled obtained in the rotation speed calculation (step S3) is set. Lower surface plate rotation speed setting (step S6) corresponds to the control process according to the present invention. Note that the rotation speed of the upper surface plate 21 may be set instead of the rotation speed of the lower surface plate 32 as described above.

In the set machining time determination (step S7), it is determined whether or not a preset machining time has been reached. If it is determined that the preset processing time has been reached, the polishing ends. If it is not determined that the preset processing time has been reached, polishing is continued, and the process advances to upper surface plate work amount measurement (step S1) and lower surface plate work amount measurement (step S4).

Hereinafter, effects of the control system of the double-side polishing apparatus 10, the control device 20, and the method of manufacturing the substrate 30 according to the embodiment will be described.

(1) According to the control system of the double-sided polishing apparatus 10 according to the present embodiment, the controller 20 controls the TOP surface work PT (Ws) required for polishing the TOP surface 30a and the BOT surface required for polishing the BOT surface 30b. Work amount PB (Ws) is calculated respectively. Further, the polishing conditions are controlled so that the difference between the calculated TOP surface work amount PT and BOT surface work amount PB, that is, the difference in work amount TB, falls within a predetermined range. As a result, by controlling the polishing conditions, the flatness of the substrate can be quickly controlled with high accuracy, and a substrate with good flatness can be obtained.

Specifically, as shown in FIG. 11(a), the frequency distribution of the workload TB difference in the conventional normal production where no workload management is performed is as follows: The range division is [-0.5 or more to less than 0], and the number of pieces within the range division of each work load difference TB of the objects W to be polished on the vertical axis is the largest, and the number of objects W to be polished is [-2. 5] to [2.5 or more]. The curve in the graph represents a normal distribution, but even the normal distribution is a smooth curve with [-0.5 or more to less than 0] as the top. In normal production, the number of objects W to be polished, that is, the number N is 2519, the average is 0.2, and σ is 1.1.

11(b), the frequency distribution of the workload TB difference of the workpiece W to be polished W on the horizontal axis is [-0 .5 or more to less than 0], the number of objects to be polished W within the range division of each work amount TB difference on the vertical axis is the largest, and the number of objects to be polished W is [-1 or more to less than -0.5 ] and [0 to less than 0.5]. The normal distribution represented by the curve in the graph is also a curve with a peak at [-1 or more to less than -0.5]. In addition, at the time of workload management, the number of objects W to be polished, that is, the number of N is 1057, the average is −0.4, and σ is 0.2.

Therefore, as a result of controlling the polishing conditions so that the work amount TB difference falls within a predetermined range, .sigma. This was confirmed, and an effect was obtained that the polishing conditions were very well controlled.

Also, FIG. 12 is a normal distribution curve and a graph of the workload TB difference in the control system of the double-sided polishing apparatus according to the embodiment of the present invention. As shown in FIG. 12, the curve indicated by the solid line of the normal distribution during workload management has a significantly high central portion, whereas the curve indicated by the broken line of the normal distribution during normal production is prominent. It has no parts and is extremely smooth. From the graph of FIG. 12 as well, it was confirmed that the variation in the work amount TB difference of the object W to be polished was extremely small.

Further, as shown in FIG. 13(a), the frequency distribution of the flatness TB difference in the conventional normal production in which the workload is not managed is as follows: In [0 or more to less than 0.5], the number of objects to be polished W within the range division of each flatness TB difference on the vertical axis is the largest, and the number of objects to be polished W is from [less than -2.5]. It spreads over a wide range of [2.5 or more]. The normal distribution represented by the curve in the graph also forms a smooth curve with [0 or more to less than 0.5] as the top. In normal production, the number of objects W to be polished, that is, the number N is 2519, the average is 0.19, and σ is 1.02.

13(b), the frequency distribution of the flatness TB difference of the object to be polished W on the horizontal axis is [-0 .5 or more to less than 0], the number of objects to be polished W within the range division of each flatness TB difference on the vertical axis is the largest, and the number of objects to be polished W is [-2 or more to less than -1.5 ] and [0.5 or more to less than 1]. The normal distribution represented by the curve in the graph is also a curve with a peak at [-1 or more to less than -0.5]. In addition, at the time of workload management, the number of objects W to be polished, that is, the number of N is 1057, the average is −0.45, and σ is 0.77.

Therefore, as a result of controlling the polishing conditions so that the difference in flatness TB falls within a predetermined range, σ was changed from 1.02 to 0.77, and the variation in the difference in flatness TB of the object W to be polished was reduced. was confirmed, and an effect was obtained that the polishing conditions were well controlled.

Also, FIG. 14 is a normal distribution curve and a graph of the flatness TB difference in the control system of the double-sided polishing apparatus according to the embodiment of the present invention. As shown in FIG. 14, the curve indicated by the solid line of the normal distribution at the time of workload management has a slightly protruding central part, whereas the curve indicated by the broken line of the normal distribution at the time of normal production is protruding. The parts are small and smooth. Also from the graph of FIG. 12, it was confirmed that the variation in the work amount TB difference of the object W to be polished was slightly reduced.

(2) According to the control system of the double-sided polishing apparatus 10 according to the present embodiment, the TOP surface workload PT and the BOT surface workload PB are It is calculated based on the rotation speed (rpm) of the platen 32, the torque (Nm) of the upper surface plate 21 and the lower surface plate 32 for polishing the object W to be polished, and the processing time T (sec) of the object W to be polished. , the effect is obtained that the TOP surface work PT and the BOT surface work PB are calculated with high accuracy.

(3) According to the control system of the double-side polishing apparatus 10 according to the present embodiment, the control device 20 calculates the TOP surface work amount PT required for polishing the TOP surface 30a by the formula (1). In formula (1), machining time T (sec), constant k, upper surface plate rotation speed NU (rpm), carrier revolution speed NC (rpm), upper surface plate torque QU (Nm), upper surface plate mechanical loss Calculation processing is performed based on torque QUM (Nm) and sampling time t (sec). Since the processing for calculating the top surface work amount PT is a definite integral from the start to the end of the processing time, the calculation processing is performed while the substrate 30 is being polished, and there is an effect that a highly accurate top surface work amount PT can be obtained. can get.

(4) According to the control system of the double-side polishing apparatus 10 according to the present embodiment, the control device 20 calculates the BOT surface work PB required for polishing the BOT surface 30b by the formula (2). In formula (2), machining time T (sec), constant k, lower surface plate rotation speed NL (rpm), carrier revolution speed NC (rpm), lower surface plate torque QL (Nm), lower surface plate mechanical loss torque QLM ( Nm) and the sampling time t (sec). Since the calculation process of the BOT surface work PB is performed by definite integration from the start to the end of the processing time, the calculation process is performed during the polishing of the substrate, and the effect is obtained that the BOT surface work PB can be obtained with high accuracy. be done.

(5) According to the control system of the double-sided polishing apparatus 10 according to the present embodiment, the predetermined range is set by the control device 20 using the flatness threshold value and the workload TB difference threshold value. , the polishing amount of the substrate 30 can be kept within a predetermined range, and the substrate 30 with good flatness can be obtained.

(6) According to the control system of the double-side polishing apparatus 10 according to the present embodiment, the controller 20 controls the difference between the TOP surface workload PT and the BOT surface workload PB during polishing of the object W to be polished. Since the upper surface plate 21 and the lower surface plate 32 are controlled, feedback control is performed more quickly, and the substrate 30 can be manufactured quickly. Specifically, as shown in FIGS. 7(a) and 7(b), the control time lag was about 1 hour and 30 minutes in the case of normal production. In terms of administration, the effect is to be shortened to about 10 minutes.

By controlling only one of the upper surface plate 21 and the lower surface plate 32, variations in the amount of polishing between the TOP surface and the BOT surface of the object W to be polished can be suppressed, and the difference in the amount of polishing worsens. can be suppressed.

Conventionally, the coefficient of friction between the polishing pad and the object W to be polished increased due to clogging or deterioration of the polishing pad, flow rate of the polishing liquid, stoppage of the object W to be polished during transportation, and the like. When the coefficient of friction between the polishing pad and the object to be polished W increases, the torque increases, so the amount of work increases. It was found that the amount of work contributing to polishing remained almost unchanged. That is, the increase in the amount of work due to the increase in the coefficient of friction may not be equal to the increase in the amount of polishing. The TB difference may get worse.

Therefore, in the control system of the double-side polishing apparatus 10 according to the present embodiment, the difference in the amount of work of TB is used for evaluation, so that the amount of work that does not contribute to polishing is offset, and the difference in amount of work TB=difference in the amount of polishing TB.

Here, a method of controlling the rotational speeds of the upper surface plate 21 and the lower surface plate 32 on both sides of the object W to be polished can be considered. Since the amount of work that does not contribute to

Therefore, the work amount of the upper surface plate 21 or the lower surface plate 32 on one side of the object to be polished W is monitored according to circumstances, and the difference in the amount of work TB is kept constant. By determining the control amount of , more rapid feedback control is performed, and a substrate with good flatness is quickly manufactured. As a specific control method, it is preferable to control the rotation speed and/or the load of the surface plate.

(7) The control device 20 according to the present embodiment includes first calculating means for calculating the TOP surface work PT (Ws) required for polishing the TOP surface 30a, and the BOT surface work PB (Ws) required for polishing the BOT surface 30b. Ws), and a control means for controlling the polishing conditions so that the difference between the TOP surface work PT and the BOT surface work PB is within a predetermined range.

With this configuration, the first calculating means calculates the TOP surface work PT (Ws) required for polishing the TOP surface 30a, and the second calculating means calculates the BOT surface work PB (Ws) required for polishing the BOT surface 30b. be done. Further, the control means controls the polishing conditions so that the difference between the calculated TOP surface work amount PT and BOT surface work amount PB is within a predetermined range. As a result, by controlling the polishing conditions, the flatness of the substrate 30 can be quickly controlled with high accuracy, and the substrate 30 with good flatness can be obtained.

(8) According to the method for manufacturing the substrate 30 according to the present embodiment, the TOP surface work PT (Ws) required for polishing the TOP surface 30a is calculated in the first calculation step, and the BOT surface 30b is polished in the second calculation step. The BOT surface work PB (Ws) required for polishing is calculated, and the polishing conditions are controlled by the control process so that the difference between the TOP surface work PT and the BOT surface work PB is within a predetermined range. As a result, by controlling the polishing conditions, the flatness of the substrate 30 can be quickly controlled with high accuracy, and the substrate 30 with good flatness can be obtained.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the scope of the invention described in the claims. Changes can be made.

REFERENCE SIGNS LIST 10 Double-sided polishing device 11 Upper surface plate portion 12 Lower surface plate portion 13 Pneumatic units 13a, 14b Piston 13b Cylinder body 13c Piston rod 14 Balancer 14a Balance cylinder 14c Wire 15 Polishing liquid supply unit 15a Pump 15b Pressure gauge 15c Open/close valve 16 Load cell 20 Control device 21 Upper surface plates 21a, 32a Pad mounting portion 21b Rod 22 Polishing pad 23 Upper surface plate drive motors 23a, 35a, 36a, 14d, 14e Pulley 23b , 35b, 36b Belt 24 Rotary shaft 24a Flange 24b Rod 25 Rod 26 Universal joint 30 Substrate 30a TOP surface 30b BOT surface 31 Table 31t Internal teeth 32 Lower surface plates 32b, 34b Shafts 33 Carriers 33t, 34t External teeth 34 Sun gear 34a Gears Part 35 Lower platen drive motor 36 Sun gear drive motor D Outer diameter d Inner diameter h Through hole k Constant NC Carrier revolution speed NL Decide Platen rotation speed NU: Upper surface plate rotation speed QL: Lower surface plate torque QLM: Torque for lower surface plate mechanical loss QU: Upper surface plate torque QUM: Torque for upper surface plate mechanical loss t・Sampling time th Thickness T Processing time W Object to be polished

Claims (8)

In a control system for a double-sided polishing apparatus that polishes the top surface and the BOT surface of the object to be polished by sandwiching the object to be polished between an upper surface plate and a lower surface plate and rotating the upper surface plate and the lower surface plate,
A TOP surface work amount PT (Ws) required for polishing the TOP surface;
Calculate the BOT surface work PB (Ws) required for polishing the BOT surface,
A double-sided polishing apparatus characterized in that polishing conditions are controlled during polishing so that a work amount difference TB, which is a difference between the calculated top surface work amount PT and the BOT surface work amount PB, is within a predetermined range. control system. The TOP surface work amount PT and the BOT surface work amount PB are calculated based on the rotation speed (rpm) and torque (Nm) of the upper surface plate and the lower surface plate and the processing time T (sec) of the object to be polished. 2. The control system for a double-sided polishing apparatus according to claim 1, wherein: The TOP surface work amount PT required for polishing the TOP surface is expressed by the following formula (1)

(In formula (1), T ₁ is the time to start measuring the work (sec), T ₂ is the time to finish measuring the work (sec), k is a constant, NU is the upper surface plate rotation speed (rpm ), NC is the carrier revolution speed (rpm), QU is the upper surface plate torque (Nm), QUM is the torque for the upper surface plate mechanical loss (Nm), and t is the sampling time (sec).)
3. The control system for a double-side polishing apparatus according to claim 1, wherein the control system is calculated by: The BOT surface work PB required for polishing the BOT surface is expressed by the following formula (2)

(In formula (2), T ₁ is the time to start measuring the work (sec), T ₂ is the time to finish measuring the work (sec), k is a constant, and NL is the lower surface plate rotation speed (rpm). , NC is the carrier revolution speed (rpm), QL is the lower surface plate torque (Nm), QLM is the lower surface plate mechanical loss torque (Nm), and t is the sampling time (sec).)
4. The control system for a double-side polishing apparatus according to claim 1, wherein the control system is calculated by: 2. A control system for a double-sided polishing apparatus according to claim 1, wherein said predetermined range is set by a threshold of flatness and a threshold of said workload TB difference. 2. A control system for a double-sided polishing apparatus according to claim 1, wherein only one of said upper surface plate and said lower surface plate is controlled based on said work load difference TB. A control device for a double-side polishing apparatus that polishes the top surface and the BOT surface of the object to be polished by sandwiching the object to be polished between an upper surface plate and a lower surface plate and rotating the upper surface plate and the lower surface plate,
a first calculating means for calculating a TOP surface work amount PT (Ws) required for polishing the TOP surface; a second calculating means for calculating a BOT surface work amount PB (Ws) required for polishing the BOT surface; Control for controlling the polishing conditions during polishing so that the difference between the top surface work amount PT calculated by the first calculating means and the BOT surface work amount PB calculated by the second calculating means is within a predetermined range. A control device for a double-sided polishing apparatus, comprising: means. In a substrate manufacturing method in which the top surface and the BOT surface of an object to be polished are polished by a double-side polishing machine,
a first calculating step of calculating a TOP surface work amount PT (Ws) required for polishing the TOP surface; a second calculating step of calculating a BOT surface work amount PB (Ws) required for polishing the BOT surface; Control for controlling the polishing conditions during polishing so that the difference between the TOP surface work amount PT calculated in the first calculation step and the BOT surface work amount PB calculated in the second calculation step is within a predetermined range. A method of manufacturing a substrate, comprising:

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