JP3374814B2 - Polishing body, planarization apparatus, semiconductor device manufacturing method, and semiconductor device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing member suitable for use in flattening and polishing a semiconductor device in a method for producing a semiconductor device such as ULSI, a flattening apparatus, a semiconductor device manufacturing method, and a semiconductor device. It is about.

[0002]

2. Description of the Related Art As semiconductor integrated circuits become highly integrated and miniaturized, the number of semiconductor manufacturing process steps is increasing and becoming complicated. Along with this, the surface of semiconductor devices is not always flat. The presence of the step on the surface of the semiconductor device causes disconnection of wiring, local increase in resistance, and the like, resulting in disconnection and reduction in electric capacity.
Further, the insulating film also causes deterioration of withstand voltage and leakage.

On the other hand, with the high integration and miniaturization of semiconductor integrated circuits, the wavelength of the light source of the semiconductor exposure apparatus used for photolithography is shortened, and the numerical aperture of the projection lens of the semiconductor exposure apparatus, so-called NA, is increased. It has become to. As a result, the depth of focus of the projection lens of the semiconductor exposure apparatus has become substantially shallow. In order to cope with the shallow depth of focus, it is required to flatten the surface of a semiconductor device more than ever.

Specifically, in the semiconductor process, the planarization technique as shown in FIGS. 8A and 8B is indispensable. Semiconductor device on silicon wafer 21
24, an interlayer insulating film 22 made of SiO ₂ and a metal film 23 made of Al are formed. FIG. 8A shows an example in which the interlayer insulating film 22 on the surface of the semiconductor device is flattened. Figure 8 (b)
Is an example of polishing a metal film 23 on the surface of a semiconductor device to form a so-called damascene. As a method of flattening the surface of such a semiconductor device, chemical mechanical polishing (Chemical Mechanical Polishing or Che
mical Mechanical Planarization (hereinafter referred to as CMP) technology is widely used. Currently, CMP technology is the only way to planarize the entire surface of a silicon wafer.

CMP has been developed based on a mirror polishing method for silicon wafers. FIG. 9 is a schematic configuration diagram of a conventional flattening apparatus used for CMP. The flattening device includes a polishing member 131, an object-to-be-polished holding unit (hereinafter referred to as a polishing head) 132, and an abrasive supply unit 134. Then, the silicon wafer 133, which is an object to be polished, is attached to the polishing head 132, and the polishing agent supply unit 134 controls the polishing agent (slurry) 1
Supply 35. The polishing member 131 includes the polishing body 13 on the surface plate 136.
7 is pasted.

The silicon wafer 133 is held by the polishing head 132, rocks while being rotated, and is pressed against the polishing body 137 of the polishing member 131 with a predetermined pressure. The polishing member 131 is also rotated so that relative movement with the silicon wafer 133 is performed. In this state, the polishing agent 135 is supplied from the polishing agent supply unit 134 onto the polishing body 137, the polishing agent 135 diffuses on the polishing body 137, and the polishing body 137 is caused by the relative movement of the polishing member 131 and the silicon wafer 133. And the silicon wafer 133, and the polishing surface of the silicon wafer 133 is polished. That is, the polishing member 131
And mechanical polishing by relative movement of the silicon wafer 133,
The chemical action of the abrasive 135 acts synergistically to achieve good polishing.

The relationship between the polishing amount of a silicon wafer and the above-mentioned polishing conditions is given by an empirical formula called Preston formula shown in (Formula 1).

R = k × P × V (Equation 1) where R is the polishing amount of the silicon wafer, P is the pressure per unit area for pressing the silicon wafer against the polishing body, and V is the relative movement of the polishing member and the silicon wafer. Relative linear velocity,
k is a proportional constant.

By the way, in CMP, the polishing rate varies due to the temperature distribution of the polishing body and the spatial difference in the supply state of the polishing agent. Further, there is a decrease in the polishing rate due to the number of processed sheets due to the change in the surface state of the polishing body, and a difference in the polishing rate due to the individual difference in the polishing body. .

Therefore, instead of the end point determination by time management, there has been proposed a method of determining the end point while in-situ measurement of motor torque, vibration and the like.
These methods use CMP that changes the material to be polished.
(For example, CMP of wiring material, CMP with stopper layer) is effective to some extent. However, in the case of a silicon wafer having a complicated pattern, it may be difficult to determine the end point because the material to be polished changes little. Further, in the case of CMP of the interlayer insulating film, since it is necessary to control the capacitance between wirings, it is required to manage the remaining film thickness, not the polishing end point. It is difficult to measure the film thickness by a method of in-situ measurement of motor torque, vibration, etc., and determining the end point.

In order to solve the above-mentioned problems, recently, in-situ end point detection and in-si detection by optical measurement, particularly spectral reflection measurement, have been performed.
Tu film thickness measurement is effective. As shown in FIG. 9, the constitution of in-situ measurement is such that an opening 138 for measurement is provided in the surface plate 136 and the polishing body 137, and the surface of the object to be polished is measured by the device 139 for measuring the polishing state through the opening 138. The method of observation is common. Although not shown in FIG. 9, a transparent window is generally installed in the polishing body 137 or the like to close the opening. Device 13 for measuring the polishing state by providing a window
The measurement light from 9 passes through the window, but the abrasive 135
It is possible to prevent leakage from 138 to the device 139 for measuring the polishing state.

So-called polishing pads made of foamed polyurethane have been used as polishing bodies. However, the polishing pad made of foamed polyurethane causes the polishing agent to be clogged and the polishing characteristics become unstable. Therefore, in the case of a foamed polyurethane polishing pad, in order to perform stable polishing, it is common to dress the polishing pad surface with a diamond grindstone. Dressing is a process to remove the clogged abrasive and at the same time scrape off the polishing pad surface of polyurethane foam to create a fresh polishing pad surface. Recently, non-foaming abrasives that do not require dressing have been used.

[0013]

However, a general transparent material such as glass or acryl is arranged as a window in the opening of the polishing body without any level difference with respect to the surface of the polishing body which contacts the object to be polished. Then, at the time of polishing, there is a problem that the window comes into contact with the silicon wafer which is the object to be polished, not only causing damage to the silicon wafer but also causing damage to the silicon wafer. Further, there is a problem that polishing tends to be non-uniform due to the contact between the window and the silicon wafer.

Even when the silicon wafer is not scratched, the window is scratched and the light intensity for measuring the polishing state passing through the window is lost, so that the accuracy of detecting the polishing end point and the accuracy of measuring the film thickness are reduced. There is a problem in that, in the worst case, the polishing end point cannot be detected and the film thickness cannot be measured.

Further, in order to reduce the loss of light intensity for measuring the polishing state, it is preferable to provide an antireflection film on the surface of the window opposite to the silicon wafer side. However, when an antireflection film is formed on a window made of a soft material, the antireflection film may crack due to bending of the window,
Since the glass transition temperature of the window is low, the window expands and contracts due to temperature changes and cracks may occur in the antireflection film. Therefore, when the window is made of a soft material, it is difficult to form the antireflection film.

Further, a soft transparent material that does not damage the silicon wafer, such as polyurethane, nylon,
When soft acrylic or the like is placed in the opening, the pressure applied to the window changes when the opening comes under the silicon wafer due to the rotation of the surface plate, and the installed window is deformed and optically distorted. Due to the distortion, the window has a function as a lens or the like, so that there is a problem that detection of the polishing end point and measurement of the film thickness become unstable.

The present invention has been made to solve the above problems, and does not damage the silicon wafer, does not cause uneven polishing, does not damage the window, and can detect the polishing end point accuracy and the film thickness. Polishing body with a window installed in the opening and flattening that does not reduce measurement accuracy and does not cause instability in detection of polishing end point and film thickness due to deformation of window The purpose is to provide a device.

[0018]

[Means for Solving the Problems] In order to solve the above problems, a polishing body according to the present invention has a polishing agent interposed between a polishing body and an object to be polished which are installed on a surface plate. ,
Applying a load between the polishing body and the object to be polished, and
A polishing body used in a flattening device for polishing an object to be polished by relative movement has an opening and a window installed in the opening, and the window is formed by laminating two or more transparent materials. (Claim 1).

According to the above-mentioned polishing body, since the windows installed in the opening are laminated with two or more transparent materials, the compressive elastic modulus (hardness) of the transparent material on the side of the object to be polished and other By changing the compressive elastic modulus (hardness) of the transparent material,
The compressive elastic modulus (hardness) of the surface on the side of the object to be polished and the compressive elastic modulus (hardness) of the surface on the side opposite to the object to be polished can be made different in the windows. Accordingly, the compressive elastic modulus (hardness) of the surface of the window can be set to a suitable value.

Further, two transparent materials are laminated on the window, and the compression elastic modulus of the transparent material of the transparent material on the side of the object to be polished has a compression elastic modulus of the transparent material on the side opposite to the object to be polished. It is preferably smaller than the elastic modulus (claim 2). As a result, the transparent material on the side opposite to the object to be polished becomes a material with a large compressive elastic modulus (hard), so that the window is not deformed, and the instability of detection of the polishing end point due to the deformation of the window and the measurement of the film thickness. Instability will not occur.

The compressive elastic modulus e of the transparent material of the transparent material on the side of the object to be polished is 2.9 × 10 ⁷ Pa ≦ e ≦ 1.47
It is preferable that it is × 10 ⁹ Pa and is almost the same as the compression elastic modulus of the polishing body (claim 3). As a result, the compression elastic modulus of the transparent material on the side of the object to be polished has almost the same value as the compression elastic modulus of the polishing body, so that the object to be polished is not damaged when the window comes into contact with the object to be polished. Disappear.
In addition, polishing non-uniformity does not occur.

Further, the surface of the window on the side of the object to be polished is recessed with respect to the surface of the polishing body which is in contact with the object to be polished, and the recess amount d is 0 μm <d ≦ 400 μm. Preferred (Claim 4). This prevents the window from coming into contact with the object to be polished, so that the object to be polished and the window are not damaged.

Further, the surface of the window on the side of the object to be polished is recessed with respect to the surface of the object to be contacted with the object to be polished, and the amount d of the recess is 0 μm <d ≦ thickness of the object to be polished. 90% of the size
And the thickness t of the window is preferably t ≧ 10% of the thickness of the polishing body (claim 5). This prevents the window from coming into contact with the object to be polished, so that the object to be polished and the window are not damaged. Furthermore, since the thickness of the window is not too thin, the window will not be deformed, and the instability of detection of the polishing end point and the instability of film thickness measurement due to the deformation of the window will not occur.

The transmittance of the window is preferably 22% or more (claim 6). As a result, the attenuation of the light intensity for measuring the polishing state passing through the window is reduced, so that the accuracy of detecting the polishing end point and the accuracy of measuring the film thickness do not deteriorate.

An antireflection film is preferably formed on the surface of the window opposite to the side of the object to be polished (claim 7). This reduces the amount of light reflected on the surface of the window for measuring the polishing state that passes through the window, and reduces the attenuation of the light intensity for measuring the polishing state. The film thickness measurement accuracy does not decrease.

In order to solve the above-mentioned problems, the flattening apparatus according to the present invention comprises a polishing body installed on a surface plate and an object to be polished with an abrasive agent interposed between the polishing body and the polishing body. In a flattening apparatus that polishes the polishing object by applying a load between the polishing objects and moving the load relative to each other, an opening formed in the surface plate and an opening formed in the polishing body. Section, a window installed so as to close at least a part of the opening formed in the polishing body, and the polishing surface of the polishing object is optically observed through the window to measure the polishing state. The opening formed in the polishing body and the opening formed in the surface plate are overlapped with each other, and the window is formed by laminating two or more transparent materials. 8).

According to the flattening apparatus, since the windows installed in the opening are laminated with two or more transparent materials, the compression elastic modulus (hardness) of the transparent material on the side of the object to be polished and other By changing the compressive elastic modulus (hardness) of the transparent material in (1), the compressive elastic modulus (hardness) of the surface on the side of the object to be polished and the compressive elastic modulus (surface) on the side opposite to the object of polishing ( Hardness) can be different. Accordingly, the compressive elastic modulus (hardness) of the surface of the window can be set to a suitable value.

Further, the window is formed by laminating two transparent materials, and the compressive elastic modulus of the transparent material of the transparent material on the side of the object to be polished is the compression of the transparent material on the side of the device for measuring the polishing state. It is preferably smaller than the elastic modulus (claim 9). As a result, the transparent material on the side of the device that measures the polishing state becomes a material with a high compression modulus (hard), so the window does not deform, and the instability of the detection of the polishing end point due to the deformation of the window and the measurement of the film thickness Instability will not occur.

Of the transparent material, on the side of the object to be polished
The compressive elastic modulus e of transparent material is 2.9 × 10 ⁷Pa ≦ e ≦ 1.47 × 10⁹P
is a and is almost the same as the compressive elastic modulus of the polishing body.
It is preferable (claim 10). This makes it possible to polish
The compressive elastic modulus of the transparent material on the object side is almost the same as the compressive elastic modulus of the polishing body.
The windows come into contact with the object to be polished because they have almost the same value.
When doing so, the object to be polished is not damaged. Furthermore
In addition, non-uniformity of polishing does not occur.

It is preferable that the surface of the window on the side of the object to be polished is recessed with respect to the surface of the polishing body that is in contact with the object to be polished, and the amount d of the recess is 0 μm <d ≦ 400 μm. Claim 11). This prevents the window from coming into contact with the object to be polished, so that the object to be polished and the window are not damaged.

Further, the surface of the window on the side of the object to be polished is dented with respect to the surface of the object to be brought into contact with the object to be polished, and the dent amount d is 0 μm <d ≦ thickness of the object to be polished. 90% of the size
And the thickness t of the window is preferably t ≧ 10% of the thickness of the polishing body (claim 1).
2). This prevents the window from coming into contact with the object to be polished, so that the object to be polished and the window are not damaged. Furthermore, since the thickness of the window is not too thin, the window will not be deformed, and the instability of detection of the polishing end point and the instability of film thickness measurement due to the deformation of the window will not occur.

Further, the device for measuring the polishing state emits light, and the light emitted from the device for measuring the polishing state passes through the window, and the light between the window and the object to be polished is removed. To an apparatus that passes through an abrasive, reflects on the polishing surface of the object to be polished, passes through the abrasive between the window and the object to be polished again, passes through the window again, and measures the polishing state. It is preferable that the ratio of the intensity of the light returning to the device for measuring the polishing state to the intensity of the light emitted from the device for measuring the polishing state is 5% or more (claim 13). As a result, the intensity of the light returning to the apparatus for measuring the polishing state becomes sufficient to measure the polishing state, so that the accuracy of detecting the polishing end point and the measurement accuracy of the film thickness by the apparatus for measuring the polishing state are reduced. Disappear.

Further, it is preferable that an antireflection film is formed on the surface of the window on the device side for measuring the polished state (claim 14). This reduces the amount of light reflected on the surface of the window and reduces the decrease in the intensity of light that returns to the device that measures the polishing state, so that the accuracy of detecting the polishing end point and the measurement accuracy of the film thickness by the device that measures the polishing state can be reduced. It will not fall.

Further, the semiconductor device manufacturing method according to the present invention has a step of flattening the surface of the semiconductor wafer by using the flattening apparatus according to the present invention (claim 15).

According to the semiconductor device manufacturing method, since the flattening apparatus according to the present invention is used in the step of flattening the surface of the semiconductor wafer, the polishing end point is detected in the step of flattening the surface of the semiconductor wafer. Since the accuracy or the measurement accuracy of the film thickness is not reduced, the yield in the step of flattening the surface of the semiconductor wafer is improved. As a result, it is possible to manufacture a semiconductor device at a lower cost than the conventional semiconductor device manufacturing method.

Further, the semiconductor device according to the present invention is
It is manufactured by the semiconductor device manufacturing method according to the present invention (claim 16).

Since the semiconductor device is manufactured by the semiconductor device manufacturing method according to the present invention,
The semiconductor device can be manufactured at a lower cost than the conventional semiconductor device manufacturing method, and the manufacturing cost of the semiconductor device can be reduced.

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings.

1A and 1B are views showing an embodiment of a polishing body according to the present invention. 1A is a top view, and FIG. 1B is a cross-sectional view taken along the line AB of FIG. 1A.

A window in which two transparent materials consisting of an upper transparent material 13 and a lower transparent material 14 are laminated is installed in an opening 12 provided in a polishing body (polishing pad) 11.
The upper transparent material 13 is a transparent material on the side of the object to be polished, and the lower transparent material 14 is a transparent material on the side opposite to the side of the object to be polished.

As the upper transparent material 13, polyurethane,
A transparent material such as acrylic, polycarbonate, polystyrene, vinyl chloride, polyethylene terephthalate, polyester, or epoxy is used.

As the lower transparent material 14, a transparent material such as glass, acrylic, polycarbonate, polystyrene, vinyl chloride, polyethylene terephthalate, polyester, or epoxy is used.

In the embodiment of the polishing body according to the present invention, two transparent materials are laminated on the window, but the number of transparent materials laminated may be three or more.

The compression elastic modulus of the upper transparent material 13 which is the transparent material on the side of the object to be polished is preferably smaller than the compression elastic modulus of the lower polishing material 14 which is the transparent material on the side opposite to the object to be polished. As a result, since the lower polishing material 14 for the window is hard, it does not deform, and there is an effect that instability in detection of the polishing end point and instability in film thickness measurement due to the deformation of the window does not occur.

Further, since the lower polishing material 14 of the window is hard, an antireflection film can be formed on the surface 14a of the lower polishing material 14. Since the anti-reflection film is formed, the light for measuring the polishing state that passes through the window is less likely to be reflected on the surface of the window, and the light intensity is less attenuated. There is an effect that the measurement accuracy of the film thickness and the film thickness does not decrease. Therefore, it is preferable that the antireflection film is formed on the surface 14a of the lower polishing material 14, which is the surface of the window opposite to the object to be polished.

The compressive elastic modulus of the upper transparent material 13, which is the transparent material on the side of the object to be polished, is preferably about the same as the compressive elastic modulus of the polishing body. The compression elastic modulus of a general abrasive body is 2.
9 × 10 ⁷ Pa or more and 1.47 × 10 ⁹ Pa or less. Therefore, the compressive elastic modulus e of the upper transparent material 13, which is the transparent material on the side of the object to be polished, is preferably 2.9 × 10 ⁷ Pa ≦ e ≦ 1.47 × 10 ⁹ Pa. This has the effect of not damaging the object to be polished when the window contacts the object to be polished.

Further, the opening 12 provided in the polishing body 11
Is a stepped hole, but the opening 12 may be a single through hole.

FIG. 2 is a schematic configuration diagram showing an embodiment of a flattening apparatus according to the present invention. The flattening apparatus according to the present invention includes a polishing member 31, a polishing object holding unit 32 (hereinafter referred to as a polishing head), and an abrasive supply unit 34. Then, a silicon wafer 33, which is an object to be polished, is attached to the polishing head 32, and a polishing agent supply unit 34 supplies a polishing agent (slurry) 35. The polishing member 31 has an opening 38.
The polishing body 11 according to the present invention described above is installed on the surface plate 36 having the above. The polishing body 11 is attached to the surface plate 36 with a double-sided tape or an adhesive. An apparatus 39 for optically observing the polishing surface of the silicon wafer 33 to be polished through the opening 38 and measuring the polishing state is also installed. In FIG. 2, the window installed in the polishing body 11 is omitted. The opening 38 formed in the surface plate 36 and the opening (not shown) formed in the polishing body 11 overlap each other. In this way, by providing the transparent window, the light 17 emitted from the device 39 for measuring the polishing state and the light reflected by the polishing surface of the silicon wafer 33 pass through the window, but the polishing agent 35 has an opening 38. Can be prevented from leaking.

The silicon wafer 33, which is the object to be polished, is held by the polishing head 32, oscillated while being rotated, and pressed against the polishing body 11 of the polishing member 31 with a predetermined pressure. The polishing member 31 is also rotated so that relative movement with the silicon wafer 33 is performed. In this state, the polishing agent 35 is supplied from the polishing agent supply unit 34 onto the polishing body 11, and the polishing agent 35 is supplied to the polishing body 11.
Diffuses above and enters between the polishing body 11 and the silicon wafer 33 with the relative movement of the polishing member 31 and the silicon wafer 33,
The polishing surface of the silicon wafer 33 is polished. That is, the polishing member
Mechanical polishing by relative movement of 31 and silicon wafer 33,
The chemical action of the abrasive 35 acts synergistically to perform good polishing.

It is preferable that the surface of the window on the side of the polishing object is recessed with respect to the surface of the polishing body 11 with which the silicon wafer 33, which is the polishing object, contacts. This prevents the silicon wafer and the window from coming into contact with each other, so that the silicon wafer is not damaged and the surface of the window is not damaged. By preventing the surface of the window from being damaged in this way,
Since the attenuation of the light 17 emitted from the device 39 for measuring the polishing state does not increase, there is an effect that the accuracy of detecting the polishing end point and the accuracy of measuring the film thickness do not decrease.

However, when the recess amount exceeds 400 μm, the amount of the polishing agent accumulated in the recess portion increases, the polishing agent becomes a scatterer, and the light emitted from the device 39 for measuring the polishing state is used.
Since 17 is attenuated, the end point detection accuracy and the film thickness detection sensitivity decrease. Therefore, the amount of depression d is 0 μm <d ≦
It is preferably 400 μm.

Further, if the thickness of the window is less than 10% of the thickness of the polishing body, the thickness of the window becomes thin, which may deform the window. Therefore, the recess amount d is 0 μm <d ≦ the thickness of the polishing body so that the thickness of the window is 10% or more of the thickness of the polishing body.
It is preferable that the length is 90%, and the thickness t of the window is t ≧ 10% of the thickness of the polishing body. As a result, there is an effect that instability in detection of the polishing end point and instability in film thickness measurement due to the deformation of the window do not occur.

The transmittance of the window is preferably 22% or more. As a result, the attenuation of the light intensity for measuring the polishing state passing through the window is reduced, so that the accuracy of detecting the polishing end point and the accuracy of measuring the film thickness are not reduced.

Further, the intensity of the light 17 emitted from the device 39 for measuring the polishing state and the intensity of the light 17 emitted from the device 39 for measuring the polishing state pass through the window and pass through the polishing agent 35 between the window and the silicon wafer 33. Then, it is reflected by the polishing surface of the silicon wafer 33,
The relationship between the intensities of the light passing through the polishing agent 35 between the window and the silicon wafer 33 again, passing through the window again, and returning to the device 39 for measuring the polishing state is the light emitted from the device 39 for measuring the polishing state.
The ratio of the intensity of light returning to the device to the intensity of 17 is preferably 5% or more. As a result, the intensity of the light returning to the apparatus for measuring the polishing state does not decrease, so that the accuracy of detecting the polishing end point and the accuracy of measuring the film thickness by the apparatus for measuring the polishing state do not decrease.

Although the window is directly installed in the opening of the polishing body in the embodiment of the present invention, the window may not be directly installed in the polishing body. For example, the window may be installed on the surface plate directly or via a jig so as to close a part of the opening of the polishing body.

FIG. 3 is a flowchart showing the semiconductor device manufacturing process. When the semiconductor device manufacturing process is started, first in step S200, an appropriate processing step is selected from the following steps S201 to S204. Depending on the selection, proceed to any of steps S201 to S204.

Step S201 is an oxidation process for oxidizing the surface of the silicon wafer. Step S202 is a CVD process for forming an insulating film on the surface of a silicon wafer by CVD or the like. Step S203 is an electrode forming step of forming electrodes on the silicon wafer by a process such as vapor deposition. Step S204 is an ion implantation step of implanting ions into the silicon wafer.

After the CVD process or the electrode forming process, the process proceeds to step S205. Step S205 is a CMP process. CMP
In the process, the flattening apparatus according to the present invention flattens the interlayer insulating film and forms a damascene by polishing the metal film on the surface of the semiconductor device.

After the CMP process or the oxidation process, step S
Continue to 206. Step S206 is a photolithography process. In the photolithography process, a resist is applied to a silicon wafer, a circuit pattern is printed on the silicon wafer by exposure using an exposure device, and the exposed silicon wafer is developed. Further, the next step S207 is an etching step in which a portion other than the developed resist image is shaved by etching, and then resist stripping is performed to remove the unnecessary resist after etching.

Next, in step S208, it is determined whether or not all necessary steps are completed. If not completed, the process returns to step S200, and the previous steps are repeated to form a circuit pattern on the silicon wafer. If it is determined in step S208 that all the processes are completed, the process ends.

In the semiconductor device manufacturing method according to the present invention, since the flattening apparatus according to the present invention is used in the CMP process, the accuracy of detecting the polishing end point or the accuracy of measuring the film thickness in the CMP process is improved. The yield in the CMP process is improved. As a result, there is an effect that the semiconductor device can be manufactured at a lower cost than the conventional semiconductor device manufacturing method.

The flattening apparatus according to the present invention may be used in the CMP process of the semiconductor device manufacturing process other than the above semiconductor device manufacturing process.

The semiconductor device according to the present invention is manufactured by the semiconductor device manufacturing method according to the present invention. As a result, the semiconductor device can be manufactured at a lower cost than the conventional semiconductor device manufacturing method, and the manufacturing cost of the semiconductor device can be reduced.

[0064]

[Embodiment] [Embodiment 1] FIG. 4 is a sectional view of a polishing body of Embodiment 1. Size 20mm x 50mm with anti-reflection film formed,
0.6 mm thick with the same size on a 0.5 mm thick acrylic plate 14
The polyurethane 13 is fixed with UV adhesive to make a two-layer window. At this time, the overall shape of the window is 20 mm x 50 mm and the thickness is 1.
It is 15 mm. In the first embodiment, the acrylic plate 14 is the lower transparent material, the polyurethane 13 is the upper transparent material, and the antireflection film is formed on the surface 14a of the acrylic plate 14 which is the lower transparent material.

20 mm in the polishing body IC1000 (code 11a) of Rodel
× 50mm opening and sub polishing body SUBA400 (11b)
An opening of 10 mm × 40 mm is provided in each layer and laminated so that the centers of the openings are aligned with each other to form a two-layer polishing body 11. Polished body IC
The compressive elastic modulus of 1000 is 7.5 × 10 ⁷ Pa, and the sub-abrasive body SUBA400
Has a compression elastic modulus of 9.6 × 10 ⁶ Pa, acrylic has a compression elastic modulus of 0.29 × 10 ¹⁰ Pa, and polyurethane has a compression elastic modulus of 7.5 × 10 ⁷ Pa. Next, the window prepared above is attached to the opening of the polishing body by sticking it with a double-sided tape having a thickness of 0.1 mm. At this time, the amount of depression of the surface of the window with respect to the surface of the polishing body is 10 μm or less.

After this, the opening 38 installed on the surface plate 36
The polishing body is attached to a flattening device (FIG. 2) having a device 39 for optically observing the polishing surface of the silicon wafer 33, which is the object to be polished, and measuring the polishing state via the. A 6-inch silicon wafer on which a 1-μm-thick thermal oxide film is formed is polished under the following conditions, and the residual film thickness of the oxide film on the silicon wafer is measured in-situ.

Rotation speed of polishing head: 50 rpm, rotation speed of polishing surface plate: 50 rpm, load (pressure at which the object to be polished is pressed against the polishing body): 2.4 × 10 ⁴ Pa, rocking: none, polishing time: 90
Second, polishing agent used: Cabot SS25 was diluted twice with ion-exchanged water, polishing agent flow rate: 200 ml / min.

The average polishing rate at this time is 430 nm / min. Further, the window does not cause scratches or uneven polishing on the silicon wafer. FIG. 5 is a graph of the reflection spectrum from the surface of the silicon wafer measured in-situ, and the curve (a) of the curves in the graph of FIG. 5 is the reflection spectrum of Example 1. In the graph of FIG. 5, the horizontal axis is the wavelength, and the vertical axis is a state in which ion-exchanged water is used instead of the polishing agent, and a silicon wafer on which aluminum is formed is placed on the window portion of the polishing body. The reflection spectroscopic spectrum of the light returning to the device 39 for measuring the polishing state at the time is set as the reference reflection spectroscopic spectrum, and is the intensity ratio of the measured reflection spectroscopic spectrum to the reference reflection spectroscopic spectrum. The polishing condition (residual film thickness of the thermal oxide film on the silicon wafer) can be measured from the waveform fitting by simulation.

[Embodiment 2] FIGS. 6A to 6K are sectional views showing the steps of manufacturing a polishing body having a window for in-situ measurement used in Embodiment 2.

Size with antireflection film 52 formed 20 mm x 50
A quartz glass plate 51 having a thickness of 1 mm and a thickness of 1 mm is prepared (see FIG. 6).
(A)), a heat-resistant tape 53 is wrapped around the quartz glass plate 51 to produce a container whose bottom is made of quartz glass (FIG. 6).
(B)). Oiled shell epoxy Epicoat 828 and Epicoat 871 were mixed at a weight ratio of 4: 6, and a resin 54 obtained by dissolving and mixing this with epoxy equivalent of p-p 'methylene dianiline as a curing agent was added to the above container. It is poured and cured by heating (FIG. 6 (c)). Next, after cutting the epoxy resin 58 parallel to the quartz glass with a cutting tool 59 or the like (FIG. 6 (d)), the epoxy resin 54 is mirror-finished by polishing, and the antireflection film / quartz glass / epoxy resin is sequentially processed from the bottom. A window 55 consisting of is obtained (FIG. 6 (e)). At this time, the thickness of the window is 1.6 mm.

An aluminum plate 57 having an opening 56 is prepared, a heat-resistant tape 53 is attached around the opening of the aluminum plate 57 (FIG. 6 (g)), and an epoxy resin 54 having the same composition as that of the window 55 is prepared. It is poured so as to have a thickness of 4 mm and cured by heating (FIG. 6 (h)). After that, in order to use the processed epoxy resin 60 as a polishing body, a heat-resistant tape around the periphery is removed, and a predetermined groove pattern is formed on the surface of the polishing body by mechanical cutting (FIG. 6).
(I)). Then, the window surface is adjusted to have the same height as the surface of the polishing body, a stepped hole is formed in the opening (FIG. 6 (j)), and the window is fixed with double-sided tape (FIG. 6). (K)). At this time, the amount of depression of the window surface with respect to the surface of the polishing body was 10 μm or less, and the surface of the window and the surface of the polishing body were substantially the same surface.

Although the aluminum plate having the opening 56 is used as the aluminum plate in the second embodiment, the aluminum plate having no opening is used, and the opening is provided in the polishing body in the step of FIG. 6 (j). At the same time, an opening may be provided in the aluminum plate.

In the second embodiment, quartz glass is the lower transparent material and epoxy resin is the upper transparent material. The compressive elastic modulus of epoxy resin is 1.47 × 10 ⁹ Pa, and the compressive elastic modulus of quartz glass is 7.31 × 10 ¹⁰ Pa.

After this, the opening 38 installed on the surface plate 36
The polishing body is attached to a flattening device (FIG. 2) having a device 39 for optically observing the polishing surface of the silicon wafer 33, which is the object to be polished, through the laser. Thickness 1
Polishing of a 6-inch silicon wafer having a thermal oxide film of μm formed is performed under the following conditions, and the residual film thickness of the oxide film on the silicon wafer is measured in-situ.

Rotation speed of the polishing head: 50 rpm, rotation speed of the polishing platen: 50 rpm, load (pressure at which the object to be polished is pressed against the polishing body): 2.4 × 10 ⁴ Pa, rocking: none, polishing time: 90
Second, polishing agent used: Cabot SS25 was diluted twice with ion-exchanged water, polishing agent flow rate: 200 ml / min.

The average polishing rate at this time is 210 nm / min. Further, the window does not cause scratches or uneven polishing on the silicon wafer. Further, the reflection spectrum from the surface of the silicon wafer obtained by the in-situ measurement is the curve (b) of FIG. 5, and the waveform fitting by simulation shows the polishing condition (residual film thickness of the thermal oxide film on the silicon wafer). It is possible to measure.

[Comparative Example 1] Size 20 m with antireflection film
An acrylic window having a size of m × 50 mm and a thickness of 2 mm is fixed in the opening portion of the polishing body prepared in the same manner as in Example 2 in the same manner as in Example 2 so that the surface of the window and the polishing body surface have the same height. . At this time, the depression of the window surface with respect to the surface of the polishing body is 10 μm or less.

After this, the opening 38 installed on the surface plate 36
The polishing body is attached to a flattening device (FIG. 2) having a device 39 for optically observing the polishing surface of the silicon wafer 33, which is the object to be polished, through the laser. Thickness 1
Polishing of a 6-inch silicon wafer having a thermal oxide film of μm formed is performed under the following conditions, and the residual film thickness of the oxide film on the silicon wafer is measured in-situ.

Rotation number of polishing head: 50 rpm, rotation number of polishing platen: 50 rpm, load (pressure at which the object to be polished is pressed against the polishing body): 2.4 × 10 ⁴ Pa, rocking: none, polishing time: 90
Second, polishing agent used: Cabot SS25 was diluted twice with ion-exchanged water, polishing agent flow rate: 200 ml / min.

In-situ measurement was performed in the same manner as in Examples 1 and 2 to obtain a reflection spectrum from the surface of the silicon wafer.
It is possible to measure the polishing condition (residual film thickness of the thermal oxide film on the silicon wafer) in-situ, but the polishing causes scratches on the silicon wafer.

[Comparative Example 2] Size 20 mm × 50 mm, thickness 2 mm
The polyurethane window is fixed to the opening of the polishing body prepared in the same manner as in Example 2 so that the surface of the window and the surface of the polishing body have the same height as in Example 2.

After this, the opening 38 installed on the surface plate 36
The polishing body is attached to a flattening device (FIG. 2) having a device 39 for optically observing the polishing surface of the silicon wafer 33, which is the object to be polished, and measuring the polishing state. Thickness 1 μm
The 6-inch silicon wafer on which the thermal oxide film is formed is polished under the following conditions, and the residual film thickness of the silicon wafer is measured in-situ using the opening.

Rotation speed of the polishing head: 50 rpm, rotation speed of the polishing platen: 50 rpm, load (pressure at which the object to be polished is pressed against the polishing body): 2.4 × 10 ⁴ Pa, rocking: none, polishing time: 90
Second, polishing agent used: Cabot SS25 was diluted twice with ion-exchanged water, polishing agent flow rate: 200 ml / min.

Further, the window does not cause scratches or uneven polishing on the silicon wafer. However, FIG. 7 is a graph of the reflection spectrum according to Comparative Example 2, and the shape of the reflection spectrum to be measured is deformed due to the deformation of the window of polyurethane, which does not match the measurement simulation, and it is difficult to measure the film thickness.

[0085]

As described above, according to the present invention, the window installed at the opening has a structure in which two or more hard transparent materials and soft transparent materials are laminated, and the transparent material on the side of the silicon wafer to be polished is the transparent material. By using a soft transparent material,
By forming the window whose surface is in the same plane as the surface of the polishing body, there is an effect that a scratch on the silicon wafer due to the window and uneven polishing are not caused. Further, there is an effect that it is possible to measure the polishing state in-situ without being affected by scattering by the polishing agent. Further, since the window is not deformed, there is an effect that the detection of the polishing end point and the instability of the film thickness measurement do not occur.

Further, by forming the antireflection film on the surface opposite to the side of the object to be polished, the loss of light quantity due to reflection is reduced, and the intensity of light for measuring the polishing state is not lost. This has the effect of not lowering the accuracy of detecting the polishing end point and the accuracy of measuring the film thickness.

Further, since the window surface is recessed with respect to the surface of the polishing body for polishing the object to be polished, the window is prevented from being damaged and the intensity of light for measuring the polishing state is lost. Disappears. This has the effect of not lowering the accuracy of detecting the polishing end point and the accuracy of measuring the film thickness.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a polishing body according to the present invention. FIG. 1A is a top view. 1 (b) is shown in FIG.
(A) It is sectional drawing of AB section.

FIG. 2 is a schematic configuration diagram of an embodiment of a flattening device according to the present invention.

FIG. 3 is a flowchart of a semiconductor device manufacturing method according to the present invention.

FIG. 4 is a sectional view of a polishing body of Example 1 of the present invention.

FIG. 5 is a reflection spectroscopy spectrum obtained by in-situ measurement. Curve (a) is Example 1 and curve (b) is Example 2
2 is a reflection spectroscopy spectrum in FIG.

FIG. 6 is a diagram showing a manufacturing process of a polishing body according to the present invention.

FIG. 7 is a reflection spectroscopy spectrum of Comparative Example 2 obtained by in-situ measurement.

FIG. 8 is a conceptual diagram of a planarization technique in a semiconductor manufacturing process and is a cross-sectional view of a semiconductor device. Figure 8 (a)
Is an example of planarizing an interlayer insulating film on the surface of a semiconductor device. FIG. 8B shows an example of polishing a metal film on the surface of a semiconductor device to form a so-called damascene.

FIG. 9 is a schematic configuration diagram of a conventional flattening apparatus used for CMP.

[Explanation of symbols]

11, 137 ... ・ Abrasive body 11a ··· Polished body IC1000 11b ・ ・ ・ ・ Abrasive body SUBA400 12 ... Opening 13 ・ ・ ・ ・ Upper transparent material 14 ... Lower transparent material 14a ... ・ Surface of lower transparent material 21 ... Silicon wafer 22 ··· Insulating film (dielectric film) 23 ... Metal wiring 24 ... Semiconductor device 31, 131 ... 32, 132 ... ・ Holding part for polishing (polishing head) 33, 133 ・ ・ ・ ・ Object of polishing (silicon wafer) 34, 134 ...- Abrasive agent supply unit 35, 135 ... ・ Abrasive (slurry) 36, 136 ... Surface plate 38, 138 ... ・ Opening 39, 139 ...- Device for measuring polishing state 51 ・ ・ ・ ・ Glass 52 .... Antireflection film 53 ... Heat resistant tape 54, 58, 60 ... Epoxy resin 55 ... window 56 ... Opening 57 ··· Aluminum plate 59 ... Bite

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B24B 37/04 H01L 21/304 622

Claims (16)

(57) [Claims] 1. A load is applied between the polishing body and the object to be polished while a polishing agent is interposed between the polishing body and the object to be polished, which are installed on a surface plate, and relative movement is performed. Thus, the polishing body used in the flattening device for polishing the object to be polished has an opening and a window installed in the opening, and the window is formed by laminating two or more transparent materials. Abrasive body characterized by being 2. The window is formed by laminating two transparent materials, and the compression elastic modulus of the transparent material of the transparent material on the side of the polishing object is the compression of the transparent material on the side opposite to the polishing object. 2. The polishing body according to claim 1, which has a smaller elastic modulus. 3. The side of the object to be polished of the transparent material
The compressive elastic modulus e of transparent material is 2.9 × 10 ⁷Pa ≦ e ≦ 1.47 × 10⁹P
is a and is almost the same as the compressive elastic modulus of the polishing body.
The abrasive body according to claim 1 or 2, characterized in that: 4. The surface of the window on the side of the object to be polished is recessed with respect to the surface of the polishing body that comes into contact with the object to be polished, and the amount d of the recess is 0 μm <d ≦ 400 μm. The abrasive body according to any one of claims 1 to 3, which is characterized in that. 5. The surface of the window on the side of the object to be polished is recessed with respect to the surface of the object to be contacted with the object to be polished, and the dent amount d is 0 μm <d ≦ thickness of the object to be polished. 90% of the length, and the thickness t of the window is t ≧ 10% of the thickness of the polishing body.
The polishing body according to any one of claims 1 to 3, characterized in that 6. The polishing body according to claim 1, wherein the window has a transmittance of 22% or more. 7. An antireflection film is formed on the surface of the window opposite to the side of the object to be polished.
7. The polishing body according to any one of 1 to 6. 8. A load is applied between the polishing body and the object to be polished while a polishing agent is interposed between the polishing body and the object to be polished, which are installed on a surface plate, and relative movement is performed. In the flattening device for polishing the object to be polished, the opening formed in the surface plate, the opening formed in the polishing body, and the polishing body installed in the polishing body, or A window installed on the surface plate so as to close at least a part of the opening formed in the body, and a polishing surface of the polishing object is optically observed through the window to measure a polishing state. The opening formed in the polishing body and the opening formed in the surface plate are overlapped with each other, and the window is formed by laminating two or more transparent materials. And flattening device. 9. The window is formed by laminating two transparent materials, and the compression elastic modulus of the transparent material of the transparent material on the side of the object to be polished is the compression of the transparent material on the side of the device for measuring the polishing state. The flattening device according to claim 8, wherein the flattening device has a smaller elastic modulus. 10. The polishing object side of the transparent material
The compressive elastic modulus e of the transparent material is 2.9 × 10 ⁷Pa ≦ e ≦ 1.47 × 10
⁹Pa and is almost the same as the compression elastic modulus of the polishing body.
The flattening device according to claim 8 or 9, wherein
Place 11. The surface of the window on the side of the object to be polished is recessed with respect to the surface of the polishing body that comes into contact with the object to be polished, and the amount d of the recess is 0 μm <d ≦ 400 μm. The flattening apparatus according to claim 8, wherein the flattening apparatus is a flattening apparatus. 12. The surface of the window on the side of the object to be polished is recessed with respect to the surface of the object to be contacted with the object to be polished, and the recess amount d is 0 μm <d ≦ thickness of the object to be polished. 90% of the length, and the thickness t of the window is t ≧ 10% of the thickness of the polishing body.
The flattening apparatus according to any one of claims 8 to 10, characterized in that 13. Light emitted from the device for measuring the polishing state passes through the window, passes through the abrasive between the window and the object to be polished, and is reflected by the polishing surface of the object to be polished. Then, the polishing agent between the window and the object to be polished is passed again, the light is passed through the window again, returns to the apparatus for measuring the polishing state, and emits the light emitted from the apparatus for measuring the polishing state. 13. The ratio of the intensity of light returning to the device for measuring the polishing state to the intensity is 5% or more.
The flattening apparatus according to any one of 1. 14. The flattening device according to claim 8, wherein an antireflection film is formed on a surface of the window on the device side for measuring the polished state. 15. A method of manufacturing a semiconductor device, comprising a step of flattening a surface of a semiconductor wafer by using the flattening apparatus according to any one of claims 8 to 14. 16. A semiconductor device manufactured by the method for manufacturing a semiconductor device according to claim 15.