JP4392818B2 - Polishing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polishing apparatus such as a precision flat lapping machine used for polishing a surface of a crystal, glass, ceramic, a single crystal silicon wafer or the like used for a substrate for a semiconductor integrated circuit.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, according to a polishing apparatus for polishing a crystal, a silicon wafer, etc., one or more guide rings are formed on a surface plate (polishing surface plate) on which a polishing cloth or the like is pasted. A cylindrical jig is positioned and arranged in advance by a guide roller. A mount plate holding a substrate to be polished such as a silicon wafer on the lower surface is mounted on the inner diameter portion of the guide ring, and a plate called a top plate is placed on the upper portion. A pressurizing shaft is connected to the center of the top surface of the top plate. While pressing to an arbitrary load through this shaft, an appropriate amount of abrasive is supplied between the surface plate and the substrate to be polished, the surface plate is rotated, and the guide ring and the substrate to be polished are held on the lower surface of the mount plate fixed. The polished substrate is polished.
[0003]
The mount plate that holds the guide ring, the top plate, and the substrate to be polished in the pressurized or depressurized state in this way is positioned around the inner and outer diameters of the rotating surface plate at the position positioned by the guide roller as the surface plate rotates. Rotates regularly due to the speed difference and improves polishing accuracy. However, this requires that the axes of the top plate, guide ring, and mount plate are perfectly aligned. This is very difficult, and slight misalignment is evenly distributed over the top plate and mount plate. Therefore, it is difficult to always desire a high-precision flat surface because load and rotation unevenness are generated in order to prevent application of a large load.
[0004]
[Problems to be solved by the invention]
However, when polishing a silicon wafer or the like with the polishing apparatus as described above, there is no problem in polishing the surface, but cracking and chipping of the substrate to be polished during polishing is reduced, and a highly accurate flat surface is obtained. In order to pursue this, there is a problem that an equal load must be applied to the mount plate.
[0005]
[Means for Solving the Problems]
The invention according to claim 1 for solving the problem is as follows:
A surface plate provided with a polishing pad on the upper surface;
A substantially cylindrical mounting plate having a substrate to be polished held on its lower surface;
A fluid passage that is substantially rotator-shaped and freely movable in the vertical direction, is formed along the central axis of the rotator, a disk-shaped space that communicates with the fluid passage, and a fluid that communicates with the space. A plurality of dispersion holes reaching the lower surface, and a top plate disposed on the upper side of the mount plate,
A mounting plate guide rollers the mounting plate to abut against the outer peripheral portion of the mounting plate is supported for rotation at a predetermined position,
A top plate guide roller where the top plate and brought into contact with the outer circumference of the top plate is supported for rotation at a predetermined position,
With
A polishing apparatus for sandwiching a substrate to be polished between the mount plate and the polishing pad and polishing the lower surface of the substrate to be polished with the polishing pad,
During polishing, the fluid flowing in through the fluid passage is filled with a uniform pressure in the space, the fluid in the space is ejected through a plurality of dispersion holes, and a uniform load is applied to the upper surface of the mount plate by the ejected fluid. granted, and a minute gap portion formed between the upper surface and the lower surface of the top plate of the mounting plate is characterized that you act as a bearing of hydrostatic or dynamic pressure type to reduce the frictional forces polishing The device.
As a method of applying a uniform load to the mount plate, the lower surface of the top plate is a static pressure or dynamic pressure bearing structure, a minute gap is created between the mount plate and the top plate, and fluid is filled between them, By eliminating the mutual restraint and making the frictional force smaller and holding each of the outer periphery of the mount plate and the top plate with independent guide rollers, the eccentric load due to the misalignment of the axis between the top plate and the mount plate can be reduced. Therefore, since it is possible to always apply a uniform load to the mount plate, high-precision polishing can be performed.
[0006]
【Example】
Hereinafter, a polishing apparatus and a polishing method for a polishing substrate according to the present invention will be described with reference to the drawings.
[0007]
FIG. 1 is an image diagram showing an example of a polishing apparatus for polishing a polishing substrate according to an embodiment of the present invention. In FIG. 1, reference numeral 11 is a surface plate, a polishing pad 12 is placed on the upper surface, and 15 is a mount plate, which is on the surface plate 11 with a substrate to be polished such as a silicon wafer held on the lower surface as in the prior art. It is placed on the polishing pad 12. A cylindrical lifting shaft 17 is disposed above the mount plate 15. A top plate 14 in which a fluid passage is formed is attached to the lower surface of the elevating shaft body 17. The fluid can be supplied to the fluid passage 20 on the lower surface of the mount plate 15 from outside through the inside of the elevating shaft body 17. Since the top plate 14 and the mount plate 15 are separated from each other, a movable top plate guide roller 18 and a mount plate guide roller 19 are arranged for positioning the top plate 14 and the mount plate 15.
[0008]
To polishing the substrate 13, such as a silicon wafer using a polishing apparatus having the above configuration, dispersing the polishing liquid on the surface plate 11, the mount plate against the plate 11 as shown in FIG. 1 15 is set so as to create a load state in which it is easy to tilt due to the presence of the polishing liquid . Next, with a slight gap between the top plate 14 and the mount plate 15, the lifting shaft 17 is fixed and fluid is installed in the top plate 14 through the internal fluid passage 20 of the lifting shaft 17 from a fluid generator (not shown). After the hollow portion 21 is once filled, the fluid is evenly discharged from the dispersion holes 22 onto the upper surface of the mount plate 15 and pressed uniformly. For this reason, the pressure applied between the upper surface of the surface plate 11 and the upper surface of the polishing pad 12 on the lower surface of the substrate to be polished 13 fixed to the lower surface of the mount plate 15 by the guide member 16 is always equal in each part of the lower surface of the substrate 13 to be polished. It is kept to become.
[0009]
By inclination 24 Gatsuku, the entire processed surface thus is supplied abrasive to the substrate to be polished deep is polished uniformly, when using a flexible polishing pad 12 to emphasize surface roughness, Figure 2 As shown, the outer peripheral side of the substrate 13 to be polished such as a silicon wafer sinks into the pad 12, and a phenomenon called edge sagging occurs and the accuracy is deteriorated. However, even if there is an inclination 24, the space that forms the static pressure or dynamic pressure type bearing structure formed between the top plate 14 and the mount plate 15 as described above fills the gaps that are wide and narrow while absorbing the movement. Positioning is performed by the fluid thus applied, and finally a uniform load is applied to the mounting plate, and a uniform load is applied to the entire processing surface to enable high-precision polishing.
[0010]
Since the thickness of the substrate 13 to be polished such as a silicon wafer gradually decreases as polishing progresses, the upper surface of the mount plate 15 holding the substrate to be polished 13 gradually lowers, and the top plate 14 also lowers. The thickness of the substrate to be polished can be measured by measuring the moving distance. In FIG. 3, the position of the top plate 14 is measured by the measuring instrument 25, and the machine is stopped at a preset dimension.
[0011]
FIG. 4 is a partial cross-sectional view of the main part of a conventional polishing apparatus. A polishing pad 12 is placed on the surface plate 11. The substrate 13 is fixed by the guide member 16 to the lower surface of the mount plate 15 positioned by the guide ring 23 on the lower surface of the top plate 14 on which the cylindrical lifting shaft 17 is disposed. The top plate 14 and the mount plate 15 are integrated by a guide ring 23 and positioned by a top pulling guide roller 18. At the end of the polishing process, the lifting shaft 17 integrated with the top plate 14 is raised by a vertical movement mechanism (not shown).
[0012]
【The invention's effect】
According to the polishing apparatus of the present invention, the top plate 14 is pressed against the top surface of the mount plate 15 by the pressure of fluid from the top plate bottom surface fluid dispersion hole 22 in a state where the mount plate 15 is not fixed to the bottom surface of the top plate 14. Therefore, the mounting plate 15 is found given a uniform load over the entire surface. For this reason, if polishing is performed using this polishing apparatus, the polishing surface of the substrate 13 to be polished such as a silicon wafer can be polished flat with high accuracy.
[0013]
In the above description, a static pressure is generated between the top plate 14 and the mount plate 15, but dynamic pressure can also be generated by changing the shape of the facing surface between the top plate 14 and the mount plate 15.
[0014]
At the end of the polishing process, when the fluid is supplied from the fluid dispersion hole 22 provided in the top plate 14 and the elevating shaft 17 is raised by the vertical movement mechanism (not shown) and the top plate 14 is pulled up, the mount plate 15, silicon wafer The to-be-polished substrate 13 and the guide member 16 are reliably cut off and left on the surface plate 11.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a substrate polishing apparatus in which a substrate to be polished holding device according to an embodiment of the present invention is used.
FIG. 2 is a schematic view of a processing state by a conventional polishing apparatus.
FIG. 3 is a schematic view of substrate thickness measurement according to a fourth embodiment of the present invention.
FIG. 4 is a schematic view of a conventional polishing apparatus.
[Explanation of symbols]
11 Surface plate 12 Polishing pad 13 Substrate 14 Top plate 15 Mount plate 16 Guide member 17 Elevating shaft 18 Top ring guide roller 19 Mount plate guide roller 20 Fluid passage 21 Space 22 Fluid dispersion hole 23 Guide ring 24 Inclination 25 Thickness measurement vessel

Claims (1)

A surface plate provided with a polishing pad on the upper surface;
A substantially cylindrical mounting plate having a substrate to be polished held on its lower surface;
A fluid passage that is substantially rotator-shaped and freely movable in the vertical direction, is formed along the central axis of the rotator, a disk-shaped space that communicates with the fluid passage, and a fluid that communicates with the space. A plurality of dispersion holes reaching the lower surface, and a top plate disposed on the upper side of the mount plate,
A mounting plate guide rollers the mounting plate to abut against the outer peripheral portion of the mounting plate is supported for rotation at a predetermined position,
A top plate guide roller where the top plate and brought into contact with the outer circumference of the top plate is supported for rotation at a predetermined position,
With
A polishing apparatus for sandwiching a substrate to be polished between the mount plate and the polishing pad and polishing the lower surface of the substrate to be polished with the polishing pad,
During polishing, the fluid flowing in through the fluid passage is filled with a uniform pressure in the space, the fluid in the space is ejected through a plurality of dispersion holes, and a uniform load is applied to the upper surface of the mount plate by the ejected fluid. granted, and a minute gap portion formed between the upper surface and the lower surface of the top plate of the mounting plate is characterized that you act as a bearing of hydrostatic or dynamic pressure type to reduce the frictional forces polishing apparatus.

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