JP2000127026A - Wafer polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a fluid pressure from being directly applied to a wafer at the time of polishing and prevent stains and spots from being left on the polished face of the wafer after polishing is completed. SOLUTION: A wafer 40 is located between an abrasive pad 35 on a surface plate 26 side and a packing pad 5 on a carrier 1 side, a fluid pressure is guided into the carrier 1 to press the wafer 40 between the abrasive pad 35 and the packing pad 5, and the surface plate 26 and the carrier 1 are rotated in different directions in this state to polish the wafer 40 in this wafer polishing device. Multiple notches 7 penetrating in the thickness direction are provided on the packing pad 5, and valve sections 8 are formed with portions surrounded by the notches 7. When the positive fluid pressure is guided into the carrier 1 for polishing the wafer 40, the valve sections 8 are closed, the wafer 40 is pressed between the packing pad 5 and the abrasive pad 35 in this state, and the wafer 40 is prevented from being directly applied with the positive fluid pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer polishing apparatus, and more particularly to a wafer polishing apparatus capable of preventing formation of stains, stains, etc. on a polished surface of a wafer such as a silicon wafer.

[0002]

2. Description of the Related Art Conventionally, as a wafer polishing apparatus of this kind,
A disk-shaped surface plate on which a polishing pad is stuck, a rotation drive mechanism for rotating and driving the surface plate, and a backing pad mounted on the surface facing the surface plate, and fluid pressure can be introduced inside. A plurality of carriers, a rotation drive mechanism for rotating each carrier in a direction opposite to the surface plate, a vertical movement mechanism for vertically moving each carrier, and a horizontal movement mechanism for horizontally moving each carrier are provided. Things are known.

In order to polish a wafer using a wafer polishing apparatus having such a configuration, first, a carrier is moved in a horizontal direction by a horizontal moving mechanism, and is positioned in a storage section for storing a wafer before polishing. Then, at this position, the carrier is lowered by the up / down moving mechanism to bring the backing pad into contact with the wafer, and a negative fluid pressure is introduced into the carrier to attract the wafer to the backing pad.

Next, the carrier is raised by a vertical moving mechanism, and the carrier is moved in a horizontal direction by a horizontal moving mechanism to be positioned above a surface plate. And
At this position, the carrier is lowered by the up-down movement mechanism to bring the wafer into contact with the polishing pad, and a positive fluid pressure is applied to the carrier to press the wafer between the backing pad and the polishing pad.

In this state, a slurry-like abrasive is supplied between the wafer and the polishing pad, and both rotation driving mechanisms are operated to rotate the carrier and the platen in directions different from each other. Polish the surface.

[0006] After the polishing of one surface of the wafer is completed, both the rotation driving mechanisms are stopped to stop the rotation of the carrier and the platen, and a negative fluid pressure is applied to the carrier to place the wafer on the backing pad. The carrier is lifted by the up-down movement mechanism, the carrier is moved horizontally by the horizontal movement mechanism, positioned in the storage section for storing the polished wafer, and a positive fluid pressure is introduced into the carrier to remove the carrier from the backing pad. The wafer is separated and the wafer is stored in the storage section.

In this manner, one surface of the wafer is polished to a predetermined surface roughness, and the polishing operation is also performed on the other surface of the wafer, thereby polishing both surfaces of the wafer to a predetermined surface roughness. Is what you can do.

[0008]

However, in the conventional polishing apparatus having the above configuration, a plurality of through holes are provided in the backing pad, and the fluid pressure introduced into the carrier through these through holes is provided. Is applied directly to the wafer, especially when a positive fluid pressure is applied, impurities contained in the fluid (rust in the piping, dust in the fluid, etc.) It adheres or soaks into the wafer from the surface of the wafer. As a result, dirt, stains, and the like remain on the polished surface of the wafer after polishing, and the quality of the product is significantly reduced.

The present invention solves the above-mentioned problems of the prior art, in which impurities (such as rust in piping and dust in the fluid) contained in the fluid adhere to the surface of the wafer. A wafer polishing apparatus capable of preventing dirt, stains, and the like from remaining on the polished surface of the wafer after polishing by preventing the product from being soaked, thereby providing a high-quality product. The purpose is to do so.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a surface plate provided with a polishing pad on a surface thereof and a carrier provided with a backing pad on a surface facing the surface plate. The wafer is positioned between the polishing pad and the backing pad by applying fluid pressure to the carrier, and the wafer is pressed between the polishing pad and the backing pad. In this state, the platen and the carrier are rotated in different directions from each other. By doing so, in the wafer polishing apparatus adapted to polish the wafer, the backing pad,
A means is provided in which a valve unit which can be opened and closed by a fluid pressure introduced into the carrier is provided, and the valve unit is closed when the wafer is polished. Further, the backing pad employs a means in which at least one cut through the thickness direction is provided at the backing pad, and the valve portion is formed at a portion surrounded by the cut.

[0011]

According to the present invention, since the valve means of the backing pad is closed when the wafer is polished, the fluid pressure introduced into the carrier does not directly act on the wafer. Instead, fluid pressure will act on the wafer via the backing pad.

[0012]

Embodiments of the present invention shown in the drawings will be described below. FIGS. 1 to 5 show an embodiment of a wafer polishing apparatus according to the present invention. The wafer polishing apparatus comprises a platen 26 on which a polishing pad 35 is adhered, and a platen 26. A rotation drive mechanism 28 for rotating the drive, a carrier 1 having a backing pad 5 mounted on a surface facing the surface plate 26, a rotation drive mechanism 10 for rotating the carrier 1 in a direction opposite to the surface plate 26, and a carrier 1 A vertical moving mechanism 21 for moving the carrier 1 in the vertical direction;
And a horizontal moving mechanism (not shown) for moving the horizontal direction.

The surface plate 26 is formed in a disk shape rotatably provided above a box-shaped base 27 via a bearing (not shown), and is provided inside the base 27. The driving mechanism 28 is driven to rotate in the horizontal direction.

The rotary drive mechanism 28 includes a motor 29 provided on the bottom side of the base 27, a transmission 31 provided on the upper side of the base 27, a rotating shaft 30 of the motor 29 and a transmission 31.
And a power transmission means 34 composed of a pulley, a belt, and the like, for connecting with the input shaft 32 of the transmission 31. The surface plate 26 is connected to the output shaft 33 of the transmission 31.

The polishing pad 35 is a disc-shaped one that is adhered to the entire surface of the platen 26 via an adhesive or the like, and is formed by impregnating a polyurethane resin, a foamed polyurethane, a nonwoven fabric, or a nonwoven fabric. Etc. are formed as a material.

The polishing pad 35 is classified into a single layer type and a multilayer type, and either type may be used. As a laminated polishing pad, for example, there is a two-layer polishing pad in which a surface hard layer is laminated on an elastic support layer. In this case, the hard polishing pad has a Shore hardness of 80 to 100 (preferably 90 to 100) and a thickness of 0.5 to 1.5 mm (preferably 0.8 to 1.3 mm).
Is used, and the elastic support layer has a Shore hardness of 50.
To 70 (preferably 50 to 65) and a thickness of 0.5 to 1.
5 mm (preferably 0.8 to 1.3 mm) is used.

The carrier 1 comprises a cylindrical casing 2 whose upper end is closed, and a disk-shaped backing pad 5 which is mounted on the lower end opening of the casing 2 and closes it. The backing pad 5 forms a sealed fluid chamber 3 inside the casing 2.

At the center of the upper end of the casing 2, a fluid chamber 3 is provided.
A through hole 4 penetrating the inside and outside is formed, and a fluid pressure source 20 such as a compressor is inserted into the fluid chamber 3 through the through hole 4.
From which a negative or positive fluid pressure is introduced.
In this case, air pressure is used as the fluid pressure, but other fluid pressures may be used.

The backing pad 5 has a disk-shaped pad portion 6 made of PET resin or the like whose upper peripheral portion is adhered to the lower end opening of the casing 2 with an adhesive or the like. An annular guide portion 9 having an upper surface side adhered to a lower peripheral edge portion, and a wafer 40 such as a disk-shaped silicon wafer is attracted to the pad portion 6 inside the guide portion 9 by suction or the like. It is supposed to be.

In the wafer suction portion of the pad portion 6, U-shaped cuts 7 penetrating the pad portion 6 in the thickness direction are formed at a plurality of places (five places in this embodiment), and are surrounded by the cuts 7. The tongue-shaped valve portions 8 are respectively formed at the portions to be formed.

In this case, the number of the valve portions 8 is not limited to five, but may be provided at five or less or at five or more. Further, the shape of the cut 7 is not limited to the U-shape, but may be a V-shape, an I-shape, a U-shape, or the like, and may be any other shape. Further, the pad portion 6 further includes
It may have two or more layers.

The guide portion 9 is made of a resin such as epoxy glass, and has an upper surface attached to a peripheral portion on the lower surface side of the pad portion 6 with an adhesive or the like. By providing the guide portion 9 in this way, it is possible to prevent the wafer 40 from shifting in the horizontal direction during polishing, and to prevent the slurry-like abrasive from entering between the wafer 40 and the pad portion 6. Can be prevented.

The carrier 1 is rotatably driven by the rotary drive mechanism 10 in a direction opposite to the surface plate 26. The rotation drive mechanism 10 includes a motor 11, a gear 13 attached to a rotation shaft 12 of the motor 11, a pipe-shaped inner rod 14 whose lower end is fitted into the through hole 4 of the casing 2 of the carrier 1, Piston rod 2
A gear 15 which meshes with the gear 13 mounted on the outer peripheral side of the bearing 4 via a bearing 17; and a support member 16 which connects between an outer ring (not shown) of the bearing 17 and an upper end of the inner rod 14. Have been.

When the motor 11 is rotated, the inner rod 14 is rotated via the gears 13 and 15, the outer ring of the bearing 17, and the support member 16, and the carrier 1 is rotated integrally with the inner rod 14. It is.

The upper end of the inner rod 14 is connected via a pipe 19 to a fluid pressure supply source 20 such as a compressor. Then, when the fluid pressure supply source 20 is operated, a negative or positive fluid pressure is introduced into the fluid chamber 3 of the carrier 1 via the pipe 19 and the inner rod 14.

The carrier 1 is vertically movable by a vertical moving mechanism 21. Vertical movement mechanism 21
Is a cylinder tube 22 into which fluid pressure can be introduced.
And a piston 23 provided reciprocally in the cylinder tube 22, and a pipe-shaped piston rod 24 penetrating through the center of the cylinder tube 22 and connected to the piston 23.

In this case, the lower end of the piston rod 24 is connected to the through hole 4 of the casing 2 of the carrier 1 via a bearing 25.
The upper end of the piston rod 24 is fitted to the inner ring (not shown) of the bearing 17 described above. Further, the inner rod 14 is inserted through the center of the piston rod 24.

Then, when a fluid pressure is introduced into the cylinder tube 22, the piston 23 reciprocates in the cylinder tube 22 in accordance with the fluid pressure, and follows the movement of the piston 23 to move the carrier 1 through the piston rod 24.
Moves up and down, and a pressure corresponding to the vertical position of the carrier 1 can be applied to the wafer 40.

Next, the operation of the above-described device will be described. First, the carrier 1 is moved in a horizontal direction by a horizontal moving mechanism (not shown) and positioned in a storage section (not shown) for storing the wafer 40 before polishing. Then, at this position, the carrier 1 is lowered by the up-and-down movement mechanism 21 to bring the wafer 40 into contact with the pad portion 6 of the backing pad 5. Then, when the fluid pressure supply source 20 is operated to introduce a negative fluid pressure into the fluid chamber 3 of the carrier 1 via the pipe 19 and the inner rod 14, the valve portion 8 of the pad portion 6 is opened and the negative pressure is opened. Acts on the wafer 40, and the wafer 40 is attracted to the pad portion 6.

Then, in this state, the carrier 1 is lifted by the vertical moving mechanism 21 and the carrier 1 is moved in the horizontal direction by a horizontal moving mechanism (not shown) to be positioned above the platen 26. Then, at this position, the carrier 1 is lowered by the up-down movement mechanism 21 to bring the wafer 40 into contact with the polishing pad 35 on the surface plate 26, and the wafer 40 is pressed by the carrier 1.

In this state, when the fluid pressure supply source 20 is operated to introduce a positive fluid pressure into the fluid chamber 3 of the carrier 1 through the pipe 19 and the inner rod 14, the pad portion 6 of the backing pad 5 Is closed, the positive fluid pressure acts on the wafer 40 via the pad portion 6, and the wafer 40 is pressed between the pad portion 6 of the backing pad 5 and the polishing pad 35.

Then, in this state, the slurry-like abrasive is supplied between the polishing pad 35 and the wafer 40, and the rotation drive mechanism 28 of the platen 26 and the rotation drive mechanism 10 of the carrier 1 are actuated. The board 26 and the carrier 1 are rotated in directions different from each other to polish one surface of the wafer 40.

After the polishing of one surface of the wafer 40 is completed, the rotation drive mechanism 28 of the platen 26 and the carrier 1
Is stopped, and the rotation of the platen 26 and the carrier 1 is stopped. And the fluid pressure supply source 20
Is operated to introduce a negative fluid pressure into the fluid chamber 3 of the carrier 1 through the pipe 19 and the inner rod 14,
When the valve portion 8 of the pad portion 6 of the backing pad 5 opens, negative fluid pressure acts on the wafer 40, and the wafer 40 is attracted to the pad portion 6.

In this state, the carrier 1 is raised by the up-down moving mechanism 21 and the carrier 1 is moved in the horizontal direction by the horizontal moving mechanism (not shown) to store the polished wafer 40. (Not shown)
Position. At this position, the carrier 1 is lowered by the up-down movement mechanism 21 and the fluid pressure supply source 20 is operated to introduce a positive fluid pressure into the fluid chamber 3 of the carrier 1 via the pipe 19 and the inner rod 14. Then, the valve portion 8 of the pad portion 6 of the backing pad 5
Is opened, the wafer 40 is separated from the pad section 6, and the wafer 40 is stored in the storage section.

In this manner, the polishing operation for one surface of the wafer 40 is completed, and the polishing operation is performed for the other surface of the wafer 40, so that both surfaces of the plurality of wafers 40 are continuously connected. Can be polished to a predetermined surface roughness.

In the wafer polishing apparatus according to this embodiment configured as described above, when polishing the wafer 40, the valve portion 8 provided on the pad portion 6 of the backing pad 5 is connected to the fluid chamber 3 of the carrier 1. Since the valve is closed by the positive fluid pressure introduced therein, the positive fluid pressure does not directly act on the wafer 40. Therefore, impurities (rust in the pipe 19, dust in the fluid, etc.) contained in the fluid do not adhere to the surface of the wafer 40 or permeate into the inside of the wafer 40, and the wafer after polishing is finished. Dirt and stains can be prevented from remaining on the 40 polished surface.

Further, since the valve portion 8 has a simple configuration in which the notch 7 is provided in the pad portion 6 of the backing pad 5, it can be easily manufactured. Therefore, there is no trouble in manufacturing the valve portion 8, so that an inexpensive product can be provided.

[0038]

According to the present invention, the valve portion provided on the backing pad is closed during polishing of the wafer, so that the positive fluid is directly applied to the wafer during polishing of the wafer. No longer works. Therefore, the impurities contained in the fluid during the polishing of the wafer (rust in the piping, dust contained in the fluid, etc.) do not adhere to the wafer or permeate into the wafer from the surface thereof. Dirt and stains do not remain on the polished surface of the wafer, and a high quality wafer can be provided. Further, since the backing pad is provided with a cut in the backing pad and the valve portion is formed in a portion surrounded by the cut, the valve portion can be easily manufactured. Therefore, an inexpensive product can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of a wafer polishing apparatus according to the present invention.

FIG. 2 is a partially enlarged cross-sectional view showing a state of the wafer shown in FIG. 1 at the time of wafer suction;

FIG. 3 is a partially enlarged sectional view showing a state of the wafer shown in FIG. 1 at the time of polishing.

FIG. 4 is a partially enlarged sectional view showing a state of the wafer shown in FIG. 1 when the wafer is separated.

FIG. 5 is a plan view showing a relationship between a backing pad and a guide unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Carrier 2 ... Casing 3 ... Fluid chamber 4 ... Through-hole 5 ... Backing pad 6 ... Pad part 7 ... Cut 8 ... Valve part 9 ... Guide part 10, 28 ... Rotation drive mechanism 11, 29 ... motor 12, 30 ... rotating shaft 13, 15 ... gear 14 ... inner rod 16 ... support member 17, 25 ... bearing 19 ... pipe 20 ... fluid pressure supply source 21 ... up and down Moving mechanism 22 Cylinder tube 23 Piston 24 Piston rod 26 Surface plate 27 Base 31 Transmission 32 Input shaft 33 Output shaft 34 Power transmission means 35 Polishing pad 40 Wafer

Claims (2)

[Claims] A surface plate on which a polishing pad is provided;
A wafer is located between a carrier provided with a backing pad on a surface facing the surface plate, and the wafer is pressed between the polishing pad and the backing pad by introducing fluid pressure to the carrier, In this state, in the wafer polishing apparatus configured to polish the wafer by rotating the surface plate and the carrier in directions different from each other, the backing pad can be opened and closed by a fluid pressure introduced into the carrier. A wafer polishing apparatus, wherein a simple valve section is provided so that the valve section closes when the wafer is polished. 2. The wafer polishing apparatus according to claim 1, wherein the backing pad is provided with at least one notch penetrating in the thickness direction, and the valve portion is formed at a portion surrounded by the notch.