JPH0549253U - Semiconductor wafer polishing machine - Google Patents

Abstract

(57) [Summary] [Object] To provide a wafer polishing machine in which a polishing liquid is uniformly supplied between a wafer and a polishing cloth. The polishing liquid is supplied without passing through a shaft for pressing the carrier plate, and preferably the carrier plate is pressed through a universal joint with the shaft. [Effect] Even if the wafer is pressed through the universal joint, the polishing liquid is smoothly supplied, and a wafer having a uniform thickness and good flatness can be obtained.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a semiconductor wafer polishing machine. More specifically, it relates to a semiconductor wafer polishing machine for polishing a semiconductor wafer of GaAs, GaP, InP, Si or the like into a mirror surface.

[0002]

[Prior Art]

 Semiconductor wafers (hereinafter simply referred to as wafers) are used as substrates for various devices. The processing process until the mirror-finished wafer supplied to the device maker is finished is explained using GaAs as an example. First, a cylindrical GaAs single crystal pulled up by the liquid-encapsulated Czochralski method or the like is outer peripherally ground to have a predetermined diameter, and subsequently cut into a wafer having a predetermined thickness by an inner peripheral blade slicer. Next, the outer edge is chamfered to increase the strength of the wafer edge to prevent damage in the subsequent processing and device processes. Next, lapping is performed to remove saw marks at the time of slicing and make the thickness of the wafer uniform, and then the work-affected layer on the surface is removed by etching and the process is continued to the polishing process. Depending on the device and the device process requirements, the wafer is finally attached to the carrier plate, and single-sided finish polishing is the final step of wafer processing.

For the substrate for semiconductor devices, particularly strict standards are set for the uniformity of the thickness of the wafer and the flatness of the polished surface. In order to obtain a good wafer, it is extremely important that the polishing liquid in which the polishing material is suspended is supplied evenly between each wafer and the polishing cloth during polishing, together with the polishing pressure, rotation speed, etc. More research has been conducted on the supply of polishing liquid.

In Japanese Unexamined Patent Publication No. 2-152770, a polishing cloth is provided on a surface plate having a rotating mechanism, and the polishing cloth is attached to a plurality of polishing plates that come into contact with the polishing cloth and slide and rotate by the rotation of the surface plate. Disclosed is a wafer polishing apparatus for polishing a plurality of wafers, wherein a polishing solution supply pipe is provided at the center of a surface plate and a polishing solution supply pipe is provided at the center of a plurality of polishing plates. ing. This will be described below with reference to FIG. The circular polishing cloth 2 is attached to the surface of a large disk-shaped polishing surface plate 3. The wafer 1 is attached to a disc-shaped carrier plate 4 by a wax 9, and the carrier plate 4 is rotatably supported by a carrier plate receiver 5 from above. A shaft 6 that engages with and presses the carrier plate receiver 5 is fixed at an axial position different from the rotation shaft 3a of the polishing platen 3 and supports the rotating carrier plate receiver 5. The polishing platen 3 located below the carrier plate 4 is forcibly rotated about the rotary shaft 3a. Then, the carrier plate 4 is rotated around the shaft 6 so that the wafer 1 slides on the polishing cloth 2. At this time, a predetermined load is imposed between the wafer 1 and the polishing cloth 2 via the shaft 6. The polishing liquid supply pipe 7 is provided so as to penetrate through the central upper portion of the polishing platen 3 and the central portion of the shaft 6 which engages and presses the carrier plate receiver 5, and the polishing liquid 8 is provided at the center of the polishing platen 3 and It is supplied at the center of the carrier plate 4.

[0005]

[Problems to be solved by the device]

 In the wafer polishing apparatus disclosed in JP-A-2-152770, as shown in FIG. 10, in order to supply the polishing liquid 8 at the center of the carrier plate 4, the polishing liquid supply pipe 7 is provided at the center of the shaft 6. It must penetrate through and open in the center of the carrier plate receiver 5 and carrier plate 4. Therefore, there is a problem that the structure of the device is greatly restricted because the through hole is provided in the engaging portion between the shaft 6 and the carrier plate receiver 5. Particularly, in an apparatus having a mechanism in which the shaft 6 and the carrier plate receiver 5 are engaged by a free joint, and the pressing force from the shaft 6 is evenly applied between the wafer 1 and the polishing cloth 2, It was impossible to apply the polishing liquid supply pipe 7 of the above.

In view of the above problems, an object of the present invention is to provide a wafer polishing machine in which a polishing liquid is uniformly supplied between a wafer and a polishing cloth without passing through a shaft that presses a carrier plate. To do.

[0007]

[Means for Solving the Problems]

 The present invention uses a polishing cloth attached to a polishing surface plate that rotates about an axis, a carrier plate that rotates about a pressure-fixed axis, and at least two semiconductor wafers attached to a polishing plate. In a semiconductor wafer polishing machine that presses and slides down to polish, the carrier plate is provided with a recess into which the polishing liquid flows at a position other than the center of the upper surface, and a pipe which penetrates the recess to the lower surface and discharges the polishing liquid. The semiconductor wafer polishing machine was constructed. Alternatively, the carrier plate is pressed through the carrier plate receiver, and the carrier plate receiver is provided with a concave portion into which polishing liquid flows at a position other than the central portion of the upper surface and a hole penetrating from the concave portion to the lower surface. A polishing machine for semiconductor wafers was provided with a pipe facing the hole and penetrating from the upper surface to the lower surface to discharge the polishing liquid. Alternatively, the carrier plate is pressed by the carrier plate receiver via the packing, and the carrier plate receiver is provided with a recess into which the polishing liquid flows at a position other than the central portion of the upper surface and a hole penetrating from the recess to the lower surface. , The packing is provided with a cavity facing the hole and penetrating from the upper surface to the lower surface, and the carrier plate is provided with a pipe facing the cavity and penetrating from the upper surface to the lower surface to discharge the polishing liquid. A wafer polisher was constructed. And, preferably, the carrier plate or the carrier plate receiver is configured to be engaged with the pressure fixing shaft by a universal joint.

[0008]

[Action]

 The polishing liquid is evenly supplied between the wafer and the polishing cloth without passing through the shaft that presses the carrier plate.

[0009]

【Example】

 A first embodiment of the present invention will be described with reference to FIGS. 1 is a side sectional view of a polishing machine, FIG. 2 is a plan view of a carrier plate to which a wafer is attached, FIG. 3 is a plan view of a carrier plate receiver, FIG. 4 is a plan view of packing, and FIG. It is a sectional side view of the carrier plate attached. The circular polishing cloth 2 is attached to the surface of a disk-shaped polishing platen 3 having a diameter of 780 mm. The wafer 1 has a diameter of 76 mm and a thickness of 0.7 mm, and four wafers 9 are attached to a disk-shaped carrier plate 4 with wax 9. The carrier plate 4 is supported from above so as to rotate integrally with the carrier plate receiver 5. ing. An annular packing 12 is inserted between the carrier plate 4 and the carrier plate receiver 5.

A shaft 6 that engages with and presses the carrier plate receiver 5 is fixed at an axial position different from the rotating shaft 3 a of the polishing platen 3, and supports a rotating carrier plate receiver 5 by a universal joint 13. The universal joint 13 has a bearing system between a recess (not shown) provided in the center of the upper surface of the carrier plate receiver 5 and the shaft 6, which enables high-speed rotation and promotes polishing efficiently. is there. The polishing platen 3 located below the carrier plate 4 is forcibly rotated about the rotation shaft 3a. Then, the carrier plate 4 is rotated around the shaft 6 so that the wafer 1 slides on the polishing cloth 2. At this time, a predetermined load is applied between the wafer 1 and the polishing cloth 2 via the shaft 6. Four shafts 6 are generally used, but a uniaxial or biaxial mechanism may be used.

A polishing liquid supply pipe 7 for supplying the polishing liquid 8 is provided above the carrier plate receiver 5 and faces a groove 10 formed in a circumferential shape on the upper surface of the carrier plate receiver 5. The carrier plate receiver 5 has a plurality of holes 11 penetrating from the groove 10 on the upper surface to the lower surface. The ring-shaped packing 12 is opposed to the hole 11 and has a central cutout portion to form a circulation space 14. A hole 15 through which the polishing liquid is discharged is provided in the center of the carrier plate 4.

Next, the polishing operation will be described. Wafers 1 are attached to carrier plate 4 with wax 9 four times, polishing liquid 8 is supplied from polishing liquid supply pipe 7 at 50 ml / min, and polishing platen 3 is rotated at 40 rpm, so that wafer 1 slides on polishing cloth 2. Then, the carrier plate 4 is copied and rotated at about 40 rpm. The carrier plate receiver 5 rotates via the packing 12.

The polishing liquid 8 flows down from the polishing liquid supply pipe 7 into the groove 10 of the carrier plate receiver 5, passes through the hole 11 and exits into the flow space 14 at the center of the packing 12, and then from the hole 15 of the carrier plate 4. The wafer 1 flows out and is supplied to the wafer 1 and the polishing cloth 2 for polishing, and the wafer 1a before polishing shown in FIG. 5 progresses uniformly with the wafer 1b after polishing to obtain a smooth polished surface with good flatness. Be done.

A second embodiment of the present invention will be described with reference to FIGS. 6 and 7. FIG. 6 is a partial side sectional view of the polishing machine, and FIG. 7 is a plan view of a carrier plate to which a wafer is attached. The description of the same or similar points as in the first embodiment will be omitted. In this embodiment, the packing 12 is not inserted between the carrier plate 4 and the carrier plate receiver 5.

A groove 10 is formed on the upper surface of the carrier plate receiver 5, and a plurality of holes 11 are formed at a position away from the center, penetrating from the upper surface to the lower surface. A plurality of holes 15 through which the polishing liquid is discharged are provided in the carrier plate 4 so as to face the holes 11.

At the time of polishing, the polishing liquid 8 flows down from the polishing liquid supply pipe 7 into the groove 10 of the carrier plate receiver 5, passes through the hole 11, and then flows out from the hole 15 of the carrier plate 4 and the wafer 1 and the polishing plate. The cloth 2 is supplied and polished. There are a plurality of holes 15 apart from the center, and the polishing liquid 8 is evenly supplied to the plurality of wafers 1 to obtain a smooth polished surface with good flatness.

A third embodiment of the present invention will be described with reference to FIGS. 8 and 9. FIG. 8 is a side sectional partial view of the polishing machine, and FIG. 9 is a plan view of a carrier plate to which a wafer is attached. The description of the same or similar points as in the first embodiment will be omitted. In this embodiment, the carrier plate 4 is directly pressed by the shaft 6 without the carrier plate receiver 5.

A groove 10 a is provided on the upper surface of the carrier plate 4, and a hole 15 for penetrating the polishing liquid from the upper surface to the lower surface is provided. The opening of the hole 15 has a large, substantially rectangular shape and is formed so as to surround the wafer 1.

At the time of polishing, the polishing liquid 8 flows down from the polishing liquid supply pipe 7 into the groove 10 a of the carrier plate 4, flows out from the hole 15, and is supplied to the wafer 1 and the polishing cloth 2 for polishing. The holes 15 are large and substantially rectangular and are formed so as to surround the wafer 1. The polishing liquid 8 is evenly supplied to the four wafers 1, and a smooth polished surface with good flatness can be obtained.

Using a GaAs wafer having a diameter of 76 mm and a thickness of 0.7 mm, 20 wafers each were polished by the polishing machine of the above-mentioned 3 examples. The average polishing amount on the entire surface of the wafer was 30 μm.

T. each of 20 polishing surfaces. T. V. , Taper and L .; T. V. The average value of was within the following range and was good. The difference (TTV) between the maximum value and the minimum value of the wafer height when the wafer is adsorbed on the reference plane is 1.2 to 2.7 μm, and the difference between the wafer height when the wafer is adsorbed on the reference plane is The slope of the least squares plane (Taper) is 0.5 to 1.2 μm, and the difference between the maximum and minimum values of the wafer height (LT) in an area within a 15 mm square with an arbitrary diameter of the wafer adsorbed on the reference plane. .V.) Was 0.6 to 1.1 μm.

[0022]

[Effect of the device]

 As described above, according to the present invention, the polishing liquid is uniformly supplied between the wafer and the polishing cloth without passing through the shaft that presses the carrier plate, and the wafer having a uniform thickness and good flatness is obtained. can get. Then, it becomes possible to press the wafer through the universal joint.

[Brief description of drawings]

FIG. 1 is a partial side sectional view of a polishing machine according to a first embodiment.

FIG. 2 is a plan view of a carrier plate to which the wafer according to the first embodiment is attached.

FIG. 3 is a plan view of a carrier plate receiver according to the first embodiment.

FIG. 4 is a plan view of the packing of the first embodiment.

FIG. 5 is a side sectional view of the carrier plate to which the wafer of the first embodiment is attached.

FIG. 6 is a partial side sectional view of a polishing machine according to a second embodiment.

FIG. 7 is a plan view of a carrier plate to which the wafer of the second embodiment is attached.

FIG. 8 is a partial side sectional view of a polishing machine according to a third embodiment.

FIG. 9 is a plan view of a carrier plate to which a wafer according to a third embodiment is attached.

FIG. 10 is a partial side sectional view of a conventional polishing machine.

[Explanation of symbols]

1. ． ． Wafer, 2. ． ． Polishing cloth, 3. ． ． Polishing surface plate, 3a. ． ． Axis of rotation, 4. ． ． Carrier plate, 5. ． ． Carrier plate receiver, 6. ． ．
Axis, 7. ． ． Polishing liquid supply pipe, 8. ． ． Polishing liquid, 9. ． ．
Wax, 10. ． ． Groove, 11. ． ． Holes, 12. ． ． Packing, 12. ． ． Packing, 13. ． ． Universal joint, 14. ． ． Distribution space, 15. ． ． Hole,

Claims (5)

[Scope of utility model registration request] 1. A polishing cloth affixed to a polishing platen rotating about an axis, and at least two or more semiconductor wafers affixed to a carrier plate rotating about a fixed pressure axis in the presence of a polishing liquid. In a semiconductor wafer polishing machine that presses and slides on a surface of the carrier plate, the carrier plate is provided with a concave portion into which a polishing liquid flows at a position other than the central portion of the upper surface, and a pipe penetrating the lower surface from the concave portion to discharge the polishing liquid. A polishing machine for semiconductor wafers characterized in that 2. The carrier plate is provided with a recess into which a polishing liquid flows in at a position other than the central portion of the upper surface, and a pipe penetrating from the recess to a lower surface to discharge the polishing liquid, instead of the carrier plate. The carrier plate receiver is pressed through the carrier plate receiver, and the carrier plate receiver is provided with a recess into which polishing liquid flows at a position other than the central portion of the upper surface, and a hole penetrating from the recess to the lower surface. The semiconductor wafer polishing machine according to claim 1, further comprising: pipes facing each other and penetrating from an upper surface to a lower surface to discharge a polishing liquid. 3. The carrier plate is provided with a recess into which the polishing liquid flows in at a position other than the central portion of the upper surface, and a pipe penetrating from the recess to the lower surface to discharge the polishing liquid, instead of the carrier plate. The packing is interposed and pressed by the carrier plate receiver, and the carrier plate receiver is provided with a recess into which polishing liquid flows at a position other than the central portion of the upper surface, and a hole penetrating from the recess to the lower surface,
The packing is provided with a cavity facing the hole and penetrating from the upper surface to the lower surface, and the carrier plate is provided with a tube facing the cavity and penetrating from the upper surface to the lower surface to discharge the polishing liquid. The semiconductor wafer polishing machine according to claim 1, wherein the polishing machine is a semiconductor wafer polishing machine. 4. The semiconductor wafer polishing machine according to claim 1, wherein the carrier plate is engaged with the pressing fixed shaft by a universal joint. 5. The semiconductor wafer polishing machine according to claim 2, wherein the carrier plate receiver is engaged with the pressing fixed shaft by a universal joint.