JP2002160156A - Carrier for polishing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carrier for polishing capable of preventing deviation of a machining object from a carrier holding hole which is caused when polishing machining or lapping machining the machining object having a large machining span and thin thickness as well as capable of preventing rapid damage and abrasion at a gear part. SOLUTION: This carrier 8 for polishing to be used for a both surfaces polishing device is provided with a circular or polygonal holding hole for supporting the machining object in a shape of a disk or a polygonal plate. A groove part 11 is formed on upper and lower surfaces of the carrier 8 along a concentric circumference having a rotating center of the carrier 8 as a center. Therefore, the pressure applied to the gear part 10 of the carrier is reduced and the pressure fluctuation uneveness is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a semiconductor wafer,
The present invention relates to a polishing carrier used for simultaneously polishing or lapping both surfaces of a workpiece such as a glass wafer and a ceramic wafer.

[0002]

2. Description of the Related Art As shown in a sectional view of FIG. 2 and a partial perspective view of FIG. The sun gear 5 rotatably fitted to the surface plate drive unit 4, the internal gear 6 provided on the outer peripheral side of the lower surface plate 3, and the gears are formed as gears which mesh with the sun gear 5 and the internal gear 6, respectively. And a polishing carrier 8 having a holding hole 9. Usually, four to six carriers 8 are arranged at the same time, but only one carrier is shown in FIG. 3 for simplification. The workpiece 7 is accommodated in the holding hole 9 of the carrier 8, is thicker than the carrier 8, and its upper surface projects upward from the upper surface of the carrier 8.

FIG. 4 is a plan view of a conventional carrier 8.
Usually, in a polishing machine carrier used for polishing or lapping of a polygonal shape such as a square for a disk-shaped workpiece such as a semiconductor wafer or a photomask substrate,
The holding holes 9 are each formed as a circular hole or a polygonal hole formed by the number of workpieces to be mounted. The carrier 8 has a plurality of guide holes 12 for uniformly guiding the abrasive liquid to the lower platen.

The polishing of the workpiece 7 mounted in the holding hole 9 of the carrier 8 is carried out by the lower platen 3 and the upper platen 2 to which an abrasive liquid is introduced and a polishing pad (not shown) is adhered. In this state, the upper and lower stools 2 and 3 are usually rotated in opposite directions. The gear 10 formed on the outer peripheral portion of the polishing carrier 8 is meshed with the internal gear 6 and the sun gear 5, and is used for polishing. The carrier 8 performs a planetary motion due to the difference in the number of revolutions of the internal gear 6 and the sun gear 5, whereby the workpiece 7 is polished or lapped on both surfaces simultaneously.

[0005]

When the workpiece 7 mounted in the holding hole 9 of the carrier 8 is to be clamped between the upper and lower stools 2 and 3 in the state shown in FIG. As the polishing progresses, the thickness of the carrier 8 and the thickness of the workpiece 7 approach each other, the frictional force between the polishing pad (not shown) and the carrier increases, and this force presses the gear 10 of the carrier 8 against the gear 10. (Compression force). Therefore, the gear 10
Wear and damage. For example, delamination and abrasion occur in epoxy and glass fiber FRP (EG). Further, as the polishing progresses, the surface roughness of the workpiece decreases, and the frictional force increases between the workpiece and the pad, which acts on the side wall of the holding hole. Then, an accident occurs in which the workpiece 7 deviates from the carrier 8. This pressure ultimately acts on the gear 10 of the carrier 8 and causes wear and damage of the gear 10. At present, workpieces tend to be thinner and larger in diameter, and it is important to prevent such deviation of the workpiece and to prevent carrier damage and wear.

As a countermeasure, a member having high rigidity is bonded to the inner periphery of the holding hole 9 to prevent the carrier from being bent, and a super-rigid substance is attached to the upper and lower surfaces of the carrier. Adhesion of ceramic composites has been proposed, but does not address processing costs.

Therefore, when using a carrier made of FRP at present, it is essential that the carrier be used below the breaking strength limit of the carrier, so that no measures can be found other than reducing the frictional force. As a measure to reduce the frictional force, the processing pressure is reduced and the rotational peripheral speed of the upper and lower platens is reduced to extend the processing time. As another means, a polishing machine with a small diameter of the platen is used to reduce the peripheral speed of the upper and lower platens, and it is difficult to reduce the cost of a large-diameter workpiece. At present, a thin stainless steel carrier is also used, but the high rigidity has an adverse effect and damages the sun gear 5 and the internal gear 6,
In addition, when the gear is twisted, the twist cannot be restored, which causes a departure accident. As a result, the polishing efficiency is high, and a large-sized polishing machine expected to reduce the polishing cost cannot be used.

Further, as the difference in thickness between the carrier 8 and the workpiece 7 is smaller, the frictional force per unit area of the polishing process is increased, so that the gear portion is damaged and worn, so that the rotational motion of the carrier is not smooth and the carrier is not smooth. Easy to deviate. For example, when the thickness of the workpiece is 1 mm or less and the diameter is 8 inches, the difference in thickness between the carrier 8 and the workpiece 7 is set to 0.4 to 0.6 mm in view of safety. If the difference is less than the above, low-load polishing is performed for the above-mentioned reason, and it becomes extremely difficult to reduce the processing cost.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned disadvantages of the prior art, and when a workpiece having a large working span and a small thickness is subjected to polishing or lapping, a workpiece formed from a holding hole is formed. An object of the present invention is to provide a polishing carrier capable of eliminating deviation and breakage and preventing abrupt wear of a gear portion.

[0010]

In order to achieve the above object, the present inventor has found that the main cause of the deviation of the workpiece from the carrier is that the workpiece is sandwiched between the polishing pads mounted on the upper and lower platens, and the variation of the clamping pressure acting on the carrier and Therefore, they found that gear damage and wear were caused by carrier torque exceeding the allowable limit. The variation in the holding pressure is not uniform due to the difference in the area of the carrier part depending on the setting of the carrier holding hole and the polishing liquid guide hole, and the pressing force applied to each gear varies. In FIG. 1, when observing the degree of damage of two gears, that is, the dotted line, that is, the portion where the workpiece is close to the gear portion and the dashed line portion, that is, the portion that is separated from the workpiece, the gear in the dashed line portion is greatly damaged and worn, Damage and wear at the dotted line are smaller than the former. The difference between the damage and the wear of the gear continuously increases from the dotted line portion to the dashed line, and decreases toward the next dotted line portion. As a result of intensive testing and research based on this fact, as a result of providing grooves on the circumference of a concentric circle centered on the rotation center of the carrier on the upper and lower surfaces (front and back surfaces) of the carrier, the abrasive friction force applied to the carrier body And the unevenness of the polishing frictional force is reduced, and the pressing pressure (compression force) acting on the gear portion 10 is reduced. In addition, it is possible to prevent kinking of the carrier caused by the rib effect of the groove against the force applied to the inner wall of the holding hole 9 of the carrier 8 due to the pressure between the upper and lower stools 2 and 3, and to prevent the workpiece from deviating. And arrived at the present invention.

The polishing carrier of the present invention is a polishing carrier having a circular or polygonal holding hole for holding a disk-shaped or polygonal-shaped workpiece to be used in a double-side polishing apparatus. The groove is formed uniformly on the circumference of the concentric circle.

According to the present invention, the carrier being polished between the upper and lower platens during the polishing operation is pressed by the holding pressure. However, the pressing is reduced in the grooves formed on the upper and lower surfaces of the carrier, and the pressing force received as the whole carrier is reduced. The pressure is alleviated, and the imbalance in the amount of friction between the dotted line and the dashed line is alleviated. At the same time, the pressure applied to the cross section of the carrier is such that the groove forms a kind of mechanical rib function between the groove and the part where the groove is not provided, which serves as a reinforcing effect, the bending of the carrier is reduced, and the holding hole of the workpiece is reduced. Departure is prevented. As a result, the pressing force applied to the self-revolving gear of the carrier is reduced, and partial damage and wear of the gear are prevented.

In one aspect of the present invention, the groove portion of the carrier is formed so that the upper and lower surfaces are concentric with the rotation center of the carrier, and the upper and lower surfaces are symmetrical and have the same dimensions. As a result, the upper and lower surfaces of the carrier receive a uniform clamping force, and the carrier is prevented from bending in the rotational direction.

In one aspect of the present invention, the dimensions of the groove are 0.05 to 0.2 mm in depth and 0.2 mm or less in width, and the groove interval is equal to or greater than the groove width.

The rib effect for preventing the deflection depends on the thickness of the carrier, the depth of the groove, and the interval between the grooves, but cannot be expected if the depth of the groove is less than 0.05 mm, and the depth is 0.2 m.
m, the thickness of the carrier is 1
mm or more is preferable. Workpiece thickness is 1mm
In the case of the above, since the material strength of the carrier is proportional to the square of the thickness and increases as much as possible, the expectation of the rib effect of the groove decreases. Rather, the number of grooves in the carrier should be increased to reduce the contact area with the pad as much as possible. However, it is preferable that the groove interval be equal to or larger than the groove width in terms of groove processing and strength.

[0016]

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

In the embodiment of the present invention, the grooves and the groove intervals where the polishing carrier 8 shown in FIG. 4 is used are not shown for the sake of detail.

FIG. 1 is a plan view showing the relative positions of the workpiece holding hole 9 of the carrier 8, the gear portion 10 and the polishing liquid guide hole 12. FIG. 4 is a schematic view of a portion showing a circular groove, which is a structure of a carrier mainly used in the present invention. In FIG. 1, the groove 11 has a depth of 0.1 to 0.2 m from the upper and lower surfaces of the carrier 8.
m, width 0.2 mm or less, groove interval 0.2 mm or more. The cutting means may be any method as long as it does not cause delamination of the FRP. If a small delamination occurs, the roughness of the processed surface is reduced to 10 μm by brush polishing or the like.
m or a thin film may be coated with the same resin. The grooves 11 are symmetrical with respect to each other on the upper and lower surfaces of the carrier and have the same diameter, and are arranged so that the frictional resistance of the relative surfaces is equivalent. This is due to the rotation of the carrier,
If the force applied to the bottom of the gear 10 exceeds the bending strength of the FRP, the bottom of the gear 10 may act as a torsional force, causing damage to the gear.

The total area of the grooves 11 of the carrier and the holding holes 9
It is preferable that the ratio of the carrier 8 to the total area excluding the abrasive liquid guide holes 12 be 50% or less.
That is, setting to 50% or less indicates that the total area of the grooves is equal to or less than the total area between the grooves. This is to reduce the contact resistance between the carrier and the polishing pad and to achieve the rib effect at the same time.
%, There is a danger of exceeding the bending strength depending on the carrier material.

The gear 10 has no groove 11. This is because the larger the contact cross-sectional area of the gear, the more secure the rotational torque of the carrier on the gear is against damage. In addition, it was determined that it was not expected from the shape of the gear that the compressive force acting on the gear section as the rotational torque could be handled by the rib effect.

[0021]

[Example] In a 20B double-side polishing machine, a glass fiber-containing epoxy resin FRP carrier conventionally available under the following polishing conditions was subjected to groove processing on the carrier surface according to the present invention, and a conventional non-grooved carrier. Table 1 shows the results of the polishing performed.

[0022]

In Table 1, the indication of the workpiece indicates that the thickness of the glass wafer is 1.2 mm or 0.8 mm for an 8-inch diameter glass wafer, respectively. The processing pressure is a load in gr units per square cm applied to the polished surface of the workpiece. The polishing rate is shown in μm unit for one minute.
The thickness of the carrier of the product of the present invention is the same as that of the conventional product before the groove processing, and the unit is mm. The risk of an accident was determined by an empirical evaluation standard for a damaged state and a worn state of the gear portion which cause the workpiece to deviate from the holding hole when the total use time of the carrier is 80 hours or less. As a polishing agent, MIRAKE SO-S was used.

Effects of the Invention As described above, according to the present invention, concentric circular grooves are formed at equal intervals on both upper and lower surfaces except for the gear portion of the carrier, so that the polishing pad is mounted on the upper and lower surfaces. The carrier that is being held by the board and being polished is pressed by the holding pressure. However, the pressing is reduced in the grooves formed on the upper and lower surfaces of the carrier, the torque applied to the gear portion is reduced, and the fluctuation width is reduced. Further, the force by which the workpiece presses the side wall of the carrier holding hole is combined with the reinforcing effect of the rib action of the groove, so that the bending of the carrier is reduced, and the workpiece is prevented from deviating from the holding hole. Also, the reduction of torque unevenness on the gear during the rotation of the carrier reduces the damage caused by abrupt delamination of a specific part of the gear, which has existed in the past, thereby extending the use time of the carrier and reducing the polishing cost. Contributed.

[Brief description of the drawings]

FIG. 1 is an enlarged plan view of a groove processing portion of a polishing carrier of the present invention.

FIG. 2 is a sectional view of a main part of the double-sided plane polishing machine.

FIG. 3 is a perspective view showing a part of the polishing machine of FIG. 2;

FIG. 4 is a plan view showing one embodiment of the polishing carrier of the present invention.

[Explanation of symbols]

 Reference Signs List 8 Carrier for polishing 9 Holding hole 10 Gear 11 Groove 12 Guide hole for abrasive liquid

Claims (4)

[Claims] 1. A polishing carrier having a circular or polygonal holding hole for holding a disk-shaped or polygonal disk-shaped workpiece to be used in a double-side polishing apparatus, wherein grooves are uniformly formed on upper and lower surfaces of the carrier. A polishing carrier, characterized in that it is formed so as to be distributed in a region. 2. The groove-shaped portion is a groove-like groove on the circumference of a concentric circle centered on the rotation center of the carrier, and is formed so as to have the same dimensions symmetrically on both upper and lower surfaces. The polishing carrier according to claim 1, wherein the carrier is a polishing carrier. 3. The groove has a depth of 0.05 to 0.2 m.
3. The polishing carrier according to claim 1, wherein m, the width is 0.2 mm or less, and the interval between the grooves is 0.2 mm or more. 4. The polishing carrier according to claim 1, wherein the carrier material is a reinforced plastic comprising a resin and a reinforcing material, and a polymer alloy.