JPH0911118A - Polishing device - Google Patents

Abstract

PURPOSE: To uniform the load distribution on a workpiece and enable the highly flat polishing by providing a taper adjusting pad expanded by filled air to form a gap between a polishing head and a plate holding a plurality of workpieces around the center shaft in the central part of the polishing head. CONSTITUTION: A plate 3 to hold a semiconductor wafer (workpiece) 2 is disposed opposedly to a polishing head 1 rotated around the center shaft, and a polishing surface table of stainless steel having an emery cloth 4 of non-woven fabric or the like bonded thereto to be rotated about the center shaft is disposed below a plate 3. Thus, the semiconductor wafer 2 is nipped between the plate 3 and the emery cloth 4 to be polished. A rod 6 connected to a cylinder device is mounted to the central part of the upper surface of the polishing head 1 to be vertically moved. A hollow taper adjusting pad 9 consisting of silicon rubber or the like and supplied with air through a gas supply path 10a is mounted to the lower surface of the polishing head 1, so that the load distribution on the workpiece 2 can be uniformed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus, and in particular,
The present invention relates to a technique effectively applied to highly flat polishing of a workpiece such as a semiconductor wafer which is a member to be polished.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, an ingot is sliced to obtain a semiconductor wafer (workpiece), which is mirror-polished to have a surface flatness of several μm or less, sometimes 1 μm.
m or less.

A polishing apparatus for mirror-polishing such a semiconductor wafer is, for example, published by the Industrial Research Committee, "VLSI Manufacturing / Testing Equipment Guidebook <1992 Edition>" (November 1991).
22), P20-P23, Ohmsha, "LSI Handbook" (November 30, 1984) P238, etc. The polishing device has a structure in which a semiconductor wafer is held on a plate and a load is applied to the polishing head to press it against the polishing platen. Specifically, a pressure ring for adjusting the load position is attached to the polishing head. Then, there is a structure in which a plurality of semiconductor wafers are held around a central axis on a plate made of glass or ceramic, and the plate is pressed against a polishing platen side by a polishing head via a pressure ring. Then, the semiconductor wafer is polished by the relative movement of the polishing cloth attached to the rotating polishing platen and the semiconductor wafer.

[0004]

However, since the polishing head and the polishing platen of the polishing apparatus are not strictly flat in general, the pressure distribution applied to the semiconductor wafer becomes non-uniform and the finished surface is deformed into a taper shape. It may happen. In addition, when a semiconductor wafer is pressed using a donut-shaped pressure ring, the rigidity of the portion not holding the semiconductor wafer is lower than that of the portion holding the semiconductor wafer. A so-called slack is generated in which the portion directly below is ground excessively. With this, it is difficult to obtain the above-mentioned level of flatness.

In particular, under the circumstances where the diameter and the height of the semiconductor wafer are increasing as in the present day, if the polished semiconductor wafer cannot have a high level of flatness, it is formed in the subsequent process. There is a possibility that serious problems may occur in the quality of the circuit elements that are present.

Therefore, an object of the present invention is to provide a technique capable of uniformizing a load distribution applied to a work and polishing the work highly flatly.

[0007] The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0008]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, typical ones will be outlined as follows.

That is, the polishing apparatus according to the present invention is provided with a polishing head that moves a workpiece relative to a rotating polishing platen while pressing the workpiece through a polishing cloth, and is provided coaxially opposite to the polishing head. And a plate for holding a plurality of works around the central axis, and a taper adjusting pad attached to the central portion of the polishing head and expanded by the filled gas to form a gap between the polishing head and the plate. It is characterized by having.

Further, the polishing apparatus according to the present invention is provided with a polishing head that presses a workpiece against a rotating polishing platen while moving the workpiece relative to the polishing table, and is provided coaxially with the polishing head so as to face the polishing head. A plate that holds a plurality of works around the central axis and a polishing head that corresponds to the held works and is expanded by the filled gas to form a gap between the polishing head and the plate. It has a plurality of work pressure pads.

The polishing apparatus according to the present invention is provided coaxially with a polishing head that moves a workpiece relative to a rotating polishing platen while pressing the workpiece with a polishing cloth, facing the polishing head. A plate that holds a plurality of workpieces around the central axis, a taper adjustment pad that is attached to the center of the polishing head, expands by the filled gas, and forms a gap between the polishing head and the plate. A plurality of work pressure pads that are attached to the polishing head corresponding to the workpiece and expand by the gas filled so that the pressure is lower than that in the taper adjustment pad to form a gap between the polishing head and the plate. It is characterized by having.

The polishing apparatus according to the present invention is provided coaxially with a polishing head that moves a workpiece relative to a rotating polishing platen while pressing the workpiece with a polishing cloth, and is coaxial with the polishing head. A plate that holds a plurality of workpieces around an axis, a taper adjustment pad that is attached to the center of the polishing head, expands by the filled gas, and forms a gap between the polishing head and the plate, and a taper adjustment pad And a work pressurizing pad that is mounted in an annular shape so as to surround the tape and expands by a gas filled so as to have a lower pressure than in the taper adjusting pad to form a gap between the polishing head and the plate. It is what

When a plurality of work pressure pads are provided,
These may be filled with a gas branched from a common gas supply path. Further, the taper adjusting pad and the work pressing pad may be made of silicon rubber.
Then, it is desirable to seal the gap between the polishing head and the plate with a seal sheet.

[0014]

According to the above-mentioned means, the work is pressed against the polishing surface plate under a uniform pressure distribution, so that the work surface can be raised without tapering or sagging. It becomes possible to polish flatly.

Further, by sealing the pad with the seal sheet, the abrasive enters between the pad and the plate and solidifies, and the size of the gap varies depending on the location, which deteriorates the polishing accuracy of the work. To be prevented.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. In all the drawings for explaining the embodiments, the same members are designated by the same reference numerals, and the repeated description thereof will be omitted.

(Embodiment 1) FIG. 1 is a cross-sectional view of an essential part showing a polishing apparatus according to an embodiment of the present invention, and FIG. 2 is an explanatory view showing a positional relationship among a plate, a pad and a semiconductor wafer in the polishing apparatus of FIG. 3 is an explanatory view showing the relationship between the plate and the polishing platen in the polishing apparatus of FIG.

As shown in FIG. 1, the polishing apparatus of this embodiment has a polishing head 1 which rotates about a central axis and a semiconductor wafer (workpiece) 2 which is provided so as to face the polishing head 1.
And a plate 3 for holding. Below the plate 3, a polishing plate 4 made of, for example, non-woven fabric is attached, and a polishing plate 5 made of stainless steel that rotates around a central axis is located. The semiconductor wafer 2 is attached to the plate 3 and the polishing cloth 4. It is sandwiched.

A rod 6 connected to a cylinder device is attached to the center of the upper surface of the polishing head 1. When the piston of the cylinder device slides, the polishing head 1 is pushed toward the polishing platen 5, As a result, the semiconductor wafer 2 having a diameter of 200 mm held on the plate 3 is pressed against the polishing cloth 4 with a force of several hundred kg. A polishing agent 8 is supplied from a pipe 7 onto the polishing cloth 4, and one surface of the semiconductor wafer 2 is moved by the polishing head 1 and the polishing surface plate 5 which rotate independently of each other. The fine abrasive grains are taken in and rubbed against the polishing cloth 4 to be polished to a predetermined flatness. The polishing head 1 may be forcibly rotated by a motor, or may be rotated with the rotation of the polishing platen 5.

A plate 3 made of, for example, ceramic is provided coaxially with the polishing head 1, and four semiconductor wafers 2 are held around the central axis of the plate 3. The number of semiconductor wafers 2 held is not limited to four and can be set freely.

A taper adjusting pad 9 made of, for example, silicon rubber and having a hollow inside is attached to the central portion of the lower surface of the polishing head 1. For example, if the inner diameter is
Air (gas) is supplied from the air supply source into the taper adjusting pad 9 of 80 mm through a gas supply passage 10a formed in the polishing head 1, and the internal pressure is set to, for example, 1 kg / cm ² .

Further, a plurality of wafer pressure pads (work pressure pads) 11 corresponding to the held semiconductor wafer 2 are attached to the lower surface of the polishing head 1 so as to surround the taper adjustment pad 9. The wafer pressing pad 11 is also made of silicon rubber and has a hollow interior, and the inner diameter is 160 mm, for example. And
Due to the air supplied through the gas supply path 10b different from the taper adjusting pad 9, the internal pressure of the wafer pressing pad 11 becomes lower than that of the taper adjusting pad 9, for example, 0.2 kg / cm.
^{It is two} .

As shown in FIG. 1, a gap N is formed between the polishing head 1 and the plate 3 by the taper adjusting pad 9 and the wafer pressing pad 11 expanded by the air. Therefore, the semiconductor wafer 2 is pressed against the polishing cloth 4 by the pressing force applied from the polishing head 1 to the plate 3 via the pads 9 and 11. In addition, a common gas supply path 10 is provided for each wafer pressing pad 11.
The air branched from b is filled, so that the inside of each wafer pressing pad 11 has the same pressure.

The positional relationship among the plate 3, the pads 9 and 11 and the semiconductor wafer 2 is as shown in FIG.
That is, these members are in a positional relationship in which the central portion of the plate 3 is pressed by the taper adjusting pad 9, and the respective wafer pressing pads 11 press the corresponding semiconductor wafer 2 via the plate 3. As described above, since the diameter of the semiconductor wafer 2 is 200 mm and the inner diameter of the corresponding wafer pressing pad 11 is 160 mm, the wafer pressing pad 11 is located right above the outer peripheral portion of the semiconductor wafer 2. The load is prevented from being concentrated on a part of the outer peripheral portion.

In such a polishing apparatus, the semiconductor wafer 2 to be polished is polished as follows.

First, the polishing head 1 is lifted up by an elevating device, the plate 3 to which the semiconductor wafer 2 is attached in advance is inserted so as to be aligned with the position of the polishing head 1, and then the polishing head 1 is lowered. After that, air is supplied so that the pressure on the wafer pressing pad 11 becomes lower than that on the taper adjusting pad 9. As a result, the semiconductor wafer 2 is
As shown in FIG. 1, pressure is applied toward the polishing platen 5 by the taper adjusting pad 9 and the wafer pressing pad 11 via the plate 3.

Here, the pads 9 and 11 for the polishing platen 5 which is generally deformed into a concave curved surface with respect to the plate 3.
The pressing forces F ₉ and F ₁₁ are expressed as a model as shown in FIG. That is, the pressing force F ₉ of the taper adjusting pad 9 that presses the central portion of the plate 3 has a higher internal pressure than the pressing force F ₁₁ of the wafer pressing pad 11 that presses the peripheral portion. growing. Therefore, FIG.
As shown in (b), the plate 3 is pressed by the pads 9 and 11 into a shape along the polishing platen 5. Then, the semiconductor wafers 2 between the plate 3 and the polishing platen 5 are individually polished by the corresponding wafer pressing pads 11.
Is pressed by.

After the above setting, the polishing agent 1 is dropped while the polishing head 1 and the polishing platen 5 are rotated to perform polishing. At this time, while the plate 3 is pressed by the taper adjusting pad 9 into a shape along the polishing surface plate 5, the semiconductor wafer 2
Since the semiconductor wafer 2 is individually pressed by the wafer pressing pad 11, the semiconductor wafer 2 is polished in a uniformly pressed state on the flat polishing surface plate 5 without concentration of load on its end surface.

Therefore, according to the polishing apparatus of this embodiment, only the portion where the semiconductor wafer 2 is attached is pressed against the polishing platen 5 under a uniform pressure distribution.
The semiconductor wafer 2 can be highly flatly polished without the finished surface becoming tapered or slack.

Since the taper adjusting pad 9 presses the plate 3 along the polishing platen 5, when the polishing platen 5 has a relatively high flatness, the taper adjusting pad 9 is used. It is also possible to only press the semiconductor wafer 2 against the polishing platen 5 with the wafer pressing pad 11 without attaching the.

(Embodiment 2) FIG. 4 is a sectional view showing a polishing apparatus according to another embodiment of the present invention, and FIG. 5 is an explanatory view showing a positional relationship among plates, pads and semiconductor wafers in the polishing apparatus shown in FIG. is there.

As shown in FIG. 4, in the polishing apparatus of this embodiment, only the taper adjusting pad 9 is attached to form the gap N between the polishing head 1 and the plate 3, The wafer pressure pad 11 shown in FIG. 1 is not provided. The polishing head 1 is formed in an annular shape so as to surround the taper adjusting pad 9 so that the plate 3 can be pressed together with the taper adjusting pad 9.

The semiconductor wafer 2 to be polished is, for example, 150 mm
When the diameter is relatively small as follows, the semiconductor wafer 2 can be highly flatly polished by merely pressing the plate 3 along the polishing platen 5 with the taper adjusting pad 9 in this way.

(Embodiment 3) FIG. 6 is an explanatory view showing a polishing apparatus which is still another embodiment of the present invention.

The polishing apparatus of this embodiment is different from the polishing apparatus according to the first embodiment in that the wafer pressing pad 11 is annularly attached so as to surround the taper adjusting pad 9. The semiconductor wafer 2 to be pressed is located immediately below the wafer pressing pad 11.

If the plate 3 can be pressed by the central taper adjusting pad 9 along the polishing platen, the pressure distribution of the semiconductor wafer 2 will be made uniform, and thus the wafer pressing pad 11 will be annularly formed. It may be provided.

(Embodiment 4) FIG. 7 is a cross-sectional view of essential parts showing a polishing apparatus according to still another embodiment of the present invention.

The polishing apparatus of this embodiment is different from the polishing apparatus shown in Embodiment 1 in that the gap N between the polishing head 1 and the plate 3 is sealed by the rubber seal sheet 12. Therefore, the taper adjustment pad 9
The wafer pressure pad 11 is in a state of being shielded from the outside by the seal sheet 12.

In this manner, by sealing the pads 9 and 11 with the seal sheet 12, the abrasive 8 applied on the polishing cloth 4 enters between the pads 9 and 11 and the plate 3 and solidifies, It is possible to prevent the accuracy of polishing the semiconductor wafer 2 from being deteriorated because the size of the gap N varies depending on the location.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, the pressure difference between the taper adjusting pad 9 and the wafer pressing pad 11 can be set freely according to the degree of warpage of the polishing platen 5, and is not limited to the numerical values shown in this embodiment. .

The semiconductor wafer 2 in this embodiment is only an example of a workpiece as a member to be polished, and other than the semiconductor wafer 2 made of single crystal silicon or compound semiconductor, for example, a magnetic disk, liquid crystal glass, or the like. It can be widely applied to the polishing of various works that require mirror finishing.

[0043]

The effects obtained by the typical inventions among the inventions disclosed in the present application will be briefly described as follows.

(1) That is, according to the polishing apparatus of the present invention, since the work is pressed against the polishing platen under a uniform pressure distribution, the finished surface becomes tapered or sags. It is possible to polish the work with high flatness without causing any defects.

(2) Further, by sealing the pad with the seal sheet, the abrasive penetrates between the pad and the plate and solidifies, and the size of the gap varies depending on the location, and the polishing accuracy of the work deteriorates. This is prevented in advance.

[Brief description of the drawings]

FIG. 1 is a sectional view of an essential part showing a polishing apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a positional relationship among a plate, a pad, and a semiconductor wafer in the polishing apparatus of FIG.

3 (a) and 3 (b) are explanatory views showing a relationship between a plate and a polishing platen in the polishing apparatus of FIG.

FIG. 4 is a sectional view showing a polishing apparatus according to a second embodiment of the present invention.

5 is an explanatory diagram showing a positional relationship among a plate, a pad, and a semiconductor wafer in the polishing apparatus of FIG.

FIG. 6 is an explanatory view showing a polishing apparatus according to a third embodiment of the present invention.

FIG. 7 is a cross-sectional view of essential parts showing a polishing device according to a fourth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 polishing head 2 semiconductor wafer (work) 3 plate 4 polishing cloth 5 polishing surface plate 6 rod 7 pipe 8 polishing agent 9 taper adjusting pad 10a gas supply path 10b gas supply path 11 wafer pressure pad (work pressure pad) 12 seal Seat F ₉ Pressing force F ₁₁ Pressing force N Clearance

Front Page Continuation (72) Inventor Hiromasa Kaita 3-3, Fujihashi, Ome City, Tokyo 2 Hitachi Tokyo Electronics Co., Ltd.

Claims (7)

[Claims] 1. A polishing head that presses a work through a polishing cloth against a rotating polishing platen while relatively moving the work, and a plurality of polishing heads are provided coaxially with the polishing head so as to face the polishing head. And a taper adjusting pad attached to the central portion of the polishing head and expanded by a filled gas to form a gap between the polishing head and the plate. Characteristic polishing device. 2. A polishing head that presses a workpiece with respect to a rotating polishing platen through a polishing cloth while moving the workpiece relative to the rotating polishing platen; A plate for holding the work pieces, and a plurality of plates attached to the polishing head corresponding to the held work pieces and expanded by a filled gas to form a gap between the polishing head and the plate. A polishing apparatus having a work pressure pad. 3. A polishing head that presses a workpiece against a rotating polishing platen through a polishing cloth and moves the workpiece relatively, and a plurality of polishing heads are provided coaxially with the polishing head so as to face the polishing head. A plate for holding the work pieces, and a taper adjusting pad attached to the central portion of the polishing head and expanded by a filled gas to form a gap between the polishing head and the plate; A plurality of workpieces attached to the polishing head corresponding to the workpieces and expanded by a gas filled so as to have a pressure lower than that in the taper adjusting pad to form a gap between the polishing head and the plate. And a pressure pad. 4. A polishing head for relatively moving a work while pressing a work through a polishing cloth against a rotating polishing platen, and a plurality of polishing heads provided coaxially to face the polishing head and having a center axis. A plate for holding the work pieces; a taper adjusting pad attached to a central portion of the polishing head and expanding by a filled gas to form a gap between the polishing head and the plate; A work pressure pad, which is annularly attached so as to surround the pad, expands by a gas filled so that the pressure is lower than that in the taper adjustment pad, and forms a gap between the polishing head and the plate. A polishing apparatus having: 5. The polishing apparatus according to claim 2, wherein the plurality of work pressure pads are filled with a gas branched from a common gas supply path. 6. The polishing apparatus according to claim 1, wherein the taper adjusting pad and the work pressure pad are made of silicon rubber. 7. The polishing apparatus according to claim 1, wherein a gap between the polishing head and the plate is sealed by a seal sheet.