JP2002355759A - Wafer polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer polishing device increasing the number of wafers polishable per batch with a long service life of abrasive cloth. SOLUTION: This wafer polishing device is provided with an injection nozzle provided facing the abrasive cloth; a polishing fluid supply mechanism for supplying a polishing fluid to the injection nozzle while pressurizing at a pressure of 0.05-0.5 MPa; an injection nozzle moving mechanism for moving the injection nozzle into a refuge position and a working position; a brush for dressing the abrasive cloth; and a brush moving mechanism for moving the brush into a refuge position and a working position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wafer polishing apparatus,
In particular, the present invention relates to a wafer polishing apparatus for polishing a compound semiconductor wafer such as GaAs.

[0002]

2. Description of the Related Art A conventional wafer polishing apparatus includes at least a polishing cloth, a base plate for mounting the polishing cloth, a base plate driving device for rotating the base plate,
The polishing apparatus is provided with a polishing liquid supply device for supplying a polishing liquid to the polishing cloth, and a carrier plate for attaching a wafer to be polished.

[0003] A circular polishing cloth made of felt or the like is attached to a base plate. The base plate is rotated by a base plate drive. Then, while the polishing liquid mainly containing sodium hypochlorite is supplied to the rotating polishing cloth by the polishing liquid supply device, the wafer attached to the carrier plate is pressed against the polishing cloth while the mechanical chemical The wafer is polished to a mirror finish.

[0004] What is mechanical chemical polishing?
The polishing literally includes both mechanical polishing and chemical polishing, but if both polishings do not work equally, the wafer will not be mirror-finished.

[0005] In the conventional wafer polishing apparatus, as the number of times of polishing increases, fine scratches (referred to as scratches) on the mirror surface of the wafer (the surface of the mirror-finished wafer) tend to increase. It becomes bad.

The cause is considered to be a decrease in the water holding capacity of the polishing cloth by the polishing liquid. That is, the pumping action of the polishing cloth caused by intermittent pressing of the polishing cloth by the wafer and restoration of the thickness of the polishing cloth decreases as the number of times of polishing increases. This decrease in the pumping action causes a decrease in the circulation effect of the polishing liquid,
The specific gravity of mechanical polishing in mechanical chemical polishing increases, and scratches occur.

Therefore, in the conventional wafer polishing apparatus, the use time of the polishing cloth is controlled, and after a certain time, the polishing operation is stopped and pure water is applied to the polishing cloth with a resin brush such as nylon. Dressing was performed by rubbing a polishing cloth.

[0008]

The conventional wafer polishing apparatus has the following problems. (1) In the above-mentioned dressing method, the above-described pumping action was not sufficiently recovered, and scratches often occurred on the mirror surface of the wafer. Therefore, the frequency of replacement of the polishing cloth must be increased in order to suppress product defects, and the cost of the polishing cloth is increased as the life of the polishing cloth is shortened. (2) The thickness restoration time of the polishing cloth during polishing is related to the amount of water retained in the polishing liquid, and the number of wafers that can be polished is limited by the amount of water retained. Conventionally, in order to increase the number of polished wafers per batch, it is necessary to increase the diameter of the base plate and the size of the polishing cloth to be attached. As a result, the price of the wafer polishing apparatus increases and the occupied area increases. was there.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a wafer polishing apparatus in which the life of a polishing pad is long and the number of polished wafers per batch is increased. .

[0010]

In order to achieve the above object, a wafer polishing apparatus according to the present invention has an injection nozzle provided to a polishing cloth, and a polishing nozzle for supplying a polishing liquid to the injection nozzle while pressurizing the same. A liquid supply mechanism, an ejection nozzle moving mechanism for moving the ejection nozzle to a retreat position and a working position, a brush for dressing the polishing pad, and a brush moving mechanism for moving the brush to a retreat position and a working position. Was configured.

The polishing liquid supply mechanism is configured to supply the polishing liquid to the spray nozzle at a pressure of 0.05 to 0.5 MPa.

The distance from the tip of the injection nozzle to the polishing surface can be adjusted within a range of 10 to 30 mm.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a plan view showing an embodiment of a wafer polishing apparatus according to the present invention. FIG. 2 is a sectional view of the wafer polishing apparatus taken along line A-C in FIG. FIG. 3 is a sectional view of the wafer polishing apparatus taken along line AB in FIG. 1 is a brush, 2
Is a wafer, 3 is a polishing cloth, 4 is a base plate, 5 is a saucer, 6 is a hollow arm, 7 is an air cylinder for a spray nozzle,
8 is a brush air cylinder, 9 is an injection nozzle, 10 is a drive unit, 11 is a spherical bearing, 12 is a polishing air cylinder, 1
Reference numeral 3 denotes an alignment bearing, 14 denotes a carrier plate, 15 denotes a ceiling cover, 16 denotes a scattering prevention cover, 17 denotes a brush rod, and 18 denotes a carrier plate rod.

The wafer polishing apparatus includes an injection nozzle 9 provided toward the polishing pad 3, a polishing liquid supply mechanism for supplying a polishing liquid to the injection nozzle 9 while pressurizing the same,
A spray nozzle moving mechanism for moving the polishing pad 3 to the retreat position I and the working position II, a brush 1 for dressing the polishing pad 3,
A brush moving mechanism for moving the brush 1 to the retracted position I and the work position II. The whole wafer polishing machine
It is covered by the ceiling cover 15 and the tray 5.

A polishing cloth 3 made of felt or the like is attached to a base plate 4 and rotated by a driving unit 10 arranged at a lower part. Then, a disc-shaped carrier plate 14 is arranged above the base plate 4, and the wafer 2 is attached to the carrier plate 14 with an adhesive.
The carrier plate 14 is configured to be able to move between the retreat position I and the working position II by the polishing air cylinder 12 and the carrier plate rod 18.

The spray nozzle moving mechanism comprises a hollow arm 6 and a spray nozzle air cylinder 7. The hollow arm 6 has an L-shape so as to vertically penetrate the ceiling cover 15 from above the ceiling cover 15 and be parallel to the polishing pad 3. The air cylinder 7 for the injection nozzle includes the hollow arm 6
To the retreat position I and the work position II.

The length of the hollow arm 6 is
And the distance (gap) between the tip of the spray nozzle 9 and the polishing surface of the polishing cloth 3 is 10 to 30 mm.
Can be adjusted. If the gap is less than 10mm,
The polishing liquid is not evenly supplied to the wafer 2 because the water flow from the injection nozzle 9 is too concentrated. On the other hand, if the gap is larger than 30 mm, the force of the water flow is reduced, and the pumping effect of the polishing pad 3 is reduced.

A gutter-shaped scattering prevention cover 16 is fixed to the lower surface of the hollow arm 6 so as to cover the plurality of injection nozzles 9, and the gap between the lower end thereof and the polishing pad 3 is made small. ing. Here, the operation of the hollow arm 6 may be configured not only to move up and down, but also to move in parallel with the polishing pad 3.

Further, the hollow arm 6 is connected to the polishing liquid supply mechanism by a hose, and is connected to each of the injection nozzles 9 by 0.05 to 0.05.
The polishing liquid is sprayed at a pressure of 0.5 MPa. Pressure is 0.
If it is larger than 5 MPa, the polishing pad 3 may be damaged.
The method of blowing the polishing liquid from the spray nozzle 9 may be such that the polishing liquid is blown out with a certain period in addition to the method of blowing out the polishing liquid by applying a constant pressure. The number of the hollow arms 6 desirably matches the number of the carrier plates 14, but may be attached to more than the number of the carrier plates 14.

The brush moving mechanism comprises a brush air cylinder 8, a brush rod 17, and a spherical bearing 11. The brush air cylinder 8 allows the brush 1 to move to the retracted position I and the working position II. The brush 1 is rotatably connected by the spherical bearing 11.

The material of the brush 1 is made of a resin such as nylon, and all the tips of the brushes are oriented perpendicular to the polishing cloth 3. The lower end of the brush air cylinder 8 is 3 to 10 mm below the position where the polishing cloth 3 and the tip of the brush 1 come into contact. If it is less than 3 mm, the contact between the tip of the brush 1 and the polishing cloth 3 is unstable, and if it exceeds 10 mm, the bristle tips of the brush 1 do not contact the polishing cloth 3 at right angles, and the thickness of the polishing cloth 3 cannot be restored.

In order to use the wafer polishing apparatus having the above configuration, first, the polishing pad 3 is attached to the base plate 4. Then, the carrier plate 14 is retracted from the polishing cloth 3 (set to the retract position I), the polishing cloth 3 is rotated, the air cylinder 7 for the injection nozzle is operated, and the hollow arm 6 is lowered to the working position II. Let it. Then, the polishing liquid supply mechanism is operated, and the polishing liquid is jetted from each jet nozzle 9. Thus, the polishing liquid can be sprayed on the entire surface of the polishing cloth 3 as the polishing cloth 3 rotates.

Thereafter, the carrier plate 14 to which the wafer 2 is attached is pressed against the polishing cloth 3 by the polishing air cylinder 12 and the carrier plate rod 18. By doing so, the carrier plate 14 can rotate freely, and the wafer can be polished. The attachment of the wafer 2 to the carrier plate 14 is not limited to the adhesive, but may be vacuum suction.

During polishing of the wafer 2, the polishing pad 3
The pumping action works due to the intermittent pressing of the polishing cloth and the restoration of the thickness of the polishing cloth, but the polishing liquid flows into the polishing cloth 3 by injecting the pressurized polishing liquid into the polishing cloth 3 and the pumping is performed. The pumping action can be forcibly recovered even for a polishing cloth having a reduced effect, the polishing precision can be increased, and the life of the polishing cloth can be extended.

During the polishing of the wafer 2, the brush 1 can be freely rotated by operating the brush air cylinder 8 to lower the brush 1 to the work position II and contact the polishing cloth 3. As a result, the thickness of the polishing pad 3 can be forcibly restored, so that the water holding power of the polishing liquid can be instantaneously increased, and the number of wafers polished per batch can be increased.

Although the spherical bearing 11 is used for the brush 1, a ball bearing having no centering function may be used. In addition, not only free rotation but also forced rotation having driving may be used. The retracting operation of the brush 1 may be configured not only to move up and down but also to move in parallel with the polishing pad 3.

In the embodiment, the description has been given of the wafer polishing apparatus of the base plate rotating type. However, the present invention is also applicable to a wafer polishing apparatus using an endless belt type polishing cloth. The wafer to be polished is not limited to GaAs, but may be other semiconductor wafers (compound semiconductors such as InP, Si) or metallic disks.

[0029]

According to the wafer polishing apparatus of the present invention, an injection nozzle provided toward a polishing cloth, and a polishing liquid supplied to the injection nozzle while being pressurized at a pressure of 0.05 to 0.5 MPa. A liquid supply mechanism, a spray nozzle moving mechanism for moving the spray nozzle to a retreat position and a work position, a brush for dressing the polishing pad, and a brush moving mechanism for moving the brush to a retreat position and a work position. Therefore, the effect that the life of the polishing cloth is long and the number of wafers that can be polished per batch increases.

[Brief description of the drawings]

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

FIG. 2 is a sectional view taken along line A-C of the wafer polishing apparatus of FIG.

FIG. 3 is a sectional view of the wafer polishing apparatus taken along line AB in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brush 2 Wafer 3 Polishing cloth 4 Base plate 5 Receiving tray 6 Hollow arm 7 Air cylinder for ejection nozzle 8 Air cylinder for brush 9 Injection nozzle 10 Driver 11 Spherical bearing 12 Air cylinder for polishing 13 Alignment bearing 14 Carrier plate 15 Ceiling cover 16 Splash prevention cover 17 Brush rod 18 Carrier plate rod I Evacuation position II Working position

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Ken Ikeda 5-1-1 Hidaka-cho, Hitachi City, Ibaraki F-term in the Hidaka Plant of Hitachi Cable, Ltd. (reference) 3C047 AA21 AA34 FF08 GG07 3C058 AA19 AC04 CB03 CB06 CB10 DA17

Claims (3)

[Claims] An injection nozzle provided toward a polishing cloth,
A polishing liquid supply mechanism for supplying a polishing liquid to the injection nozzle while applying pressure, an injection nozzle moving mechanism for moving the injection nozzle to a retreat position and a working position, a brush for dressing the polishing pad, and a retreat position for the brush And a brush moving mechanism for moving to a work position. 2. The wafer polishing apparatus according to claim 1, wherein the polishing liquid supply mechanism is configured to supply the polishing liquid to the injection nozzle at a pressure of 0.05 to 0.5 MPa. . 3. The wafer polishing apparatus according to claim 1, wherein the distance from the tip of the injection nozzle to the polishing surface can be adjusted within a range of 10 to 30 mm.