JP2022100742A - Both-face grinding carrier and wafer grinding method - Google Patents

Abstract

To make it possible to make a wafer smoothly revolve in a hole, and to reduce a local deformation of a grinding pad caused by a load.SOLUTION: In a both-face grinding carrier 11, a plurality of protrusive curved faces 13A protruding toward a hole center C2, and a plurality of recessive curved faces 13B recessed so as to separate from the hole center C2 are alternately formed at an internal peripheral face of a hole 13. All of the protrusive curved faces 13A and all of the recessive curved faces 13b are formed in the same sizes and at the same pitches; the protrusive curved faces 13A are formed into circular arc shapes or secondary curved linear shapes; and a virtual line for connecting apexes of the protrusive curved faces 13A in a circular shape is formed so as to form a circular shape having a magnitude for allowing a stay of a wafer 12. Two pieces of the adjoining protrusive curved faces 13A are formed so as to point-contact with the wafer 12. The recessive curved faces 13B are arranged with clearances large enough not to contact with the wafer 12 when the two pieces of adjoining protrusive curved faces 13A point-contact with the wafer 12.SELECTED DRAWING: Figure 1

Description

The present invention relates to a disk-shaped double-sided polishing carrier used for double-sided polishing of a disk-shaped wafer and a wafer polishing method for polishing both sides of a wafer using the double-sided polishing carrier.

Normally, for disc-shaped wafers such as semiconductor wafers, double-sided polishing is performed by supplying a polishing liquid (slurry) while sandwiching the wafer between the upper surface plate and the lower surface plate to which the polishing pad is attached, and polishing both sides at the same time. It has been damaged. At that time, the wafer is held by a circular hole (holding hole) formed in the carrier for double-sided polishing. In such general double-sided polishing, since the contact point between the wafer and the hole is constantly one point, there is a problem that the action of rotating the wafer from the carrier is difficult to be transmitted.

Patent Document 1 describes the double-sided polishing carrier 1 shown in FIG. The double-sided polishing carrier 1 has a disk shape, and a plurality of holes 3 (4 in FIG. 6) for holding the wafer 2 are formed therein, and outer peripheral teeth 4 are formed on the outer peripheral portion at a predetermined pitch. ..

The size of the hole 3 is a size that holds the wafer 2 rotatably. The inner peripheral surface of the hole 3 is formed by connecting a plurality of convex surfaces 3A at substantially the same pitch. The convex surface 3A has an arc shape having substantially the same size. When the wafer 2 is polished on both sides, the tops of the plurality of convex surfaces 3A make point contact with the outer peripheral surface of the wafer 2. Therefore, the wafer 2 can rotate in the hole 3 as the double-sided polishing carrier 1 moves.

Japanese Unexamined Patent Publication No. 2001-138221

In the double-sided polishing carrier 1 described in Patent Document 1, the inner peripheral surface of the hole 3 is formed by connecting an arcuate convex surface 3A that makes point contact with the wafer 2. As shown in FIG. 7, which is an enlarged view of a part of P1 of FIG. 6, when the outer peripheral surface of the wafer 2 comes into contact with each convex surface 3A, the periphery of the concave portion 3B which is the connecting portion of each convex surface 3A and the outer peripheral portion of the wafer 2 (Hereinafter abbreviated as "wafer outer peripheral portion".) A relatively large space 5 is formed between the wafer and the wafer.

When the wafer 2 is double-sided polished using the double-sided polishing carrier 1, the polishing pad 6 enters the space 5 due to the polishing load and locally as shown in FIG. 8 which is an enlarged cross-sectional view taken along the line AA'in FIG. It will be in a deformed state. Therefore, the upper edge of the outer peripheral portion 2A of the wafer, that is, the corner portion in contact with the polishing pad 6 is cut into an R shape. As a result, the strength of the outer peripheral portion 2A of the wafer is lowered, and chipping or the like is likely to occur.

An object of the present invention is to provide a carrier for double-sided polishing and a method for polishing a wafer, which can smoothly rotate a wafer in a hole and reduce local deformation of a polishing pad due to a load.

The present invention relates to a disk-shaped double-sided polishing carrier having a hole for accommodating a disk-shaped wafer, and has a convex curved surface protruding toward the center of the hole on the inner peripheral surface of the hole and the center of the hole. A plurality of concave curved surfaces recessed away from the surface are alternately formed, all of the convex curved surfaces are formed with the same size and the same pitch, and all of the concave curved surfaces are formed with the same size and the same pitch. Each convex curved surface is formed into an arc shape or a quadratic curved surface shape, and the virtual line connecting the vertices of each convex curved surface in a circular shape has a circular shape having a size that allows the wafer to stay. The two adjacent convex curved surfaces are formed so as to make point contact with the wafer, and each of the concave curved surfaces is said when the two adjacent convex curved surfaces make point contact with the wafer. It is arranged with a gap that does not come into contact with the wafer.

In the double-sided polishing carrier according to the present invention, the angle formed by the two lines connecting the two adjacent vertices of the convex curved surface and the center of the hole is 10 ° or more and 72 ° or less. It is formed.

In the double-sided polishing carrier according to the present invention, the gap is 0.1% or more and 0.6% or less of the diameter of the wafer.

The present invention relates to a disk-shaped double-sided polishing carrier having a hole for accommodating a disk-shaped wafer, and the inner peripheral surface of the hole passes through an intermediate point of each side of a regular polygon and is inscribed in the regular polygon. It is composed of a curved surface equal to or larger than a circle, the hole is formed so that the wafer is in point contact with the intermediate point of two adjacent sides of the regular polygon, and the curved surface is formed of each of the regular polygons. It is formed with a gap that does not come into contact with the wafer when the wafer comes into point contact with the intermediate point of two adjacent sides.

In the double-sided polishing carrier according to the present invention, the regular polygon is a regular pentagon or more and a regular hexadecagon or less.

In the double-sided polishing carrier described in paragraph 0012 or paragraph 0013 of the present invention, the gap is 0.1% or more and 0.6% or less of the diameter of the wafer.

In the wafer polishing method according to the present invention, both sides of the wafer are polished using the double-sided polishing carrier.

According to the present invention, the wafer can rotate smoothly in the hole, and the local deformation of the polishing pad due to the load can be reduced.

It is a top view which shows an example of the structure of the carrier for double-sided polishing which concerns on 1st Embodiment of this invention. It is an enlarged view of a part P2 of FIG. It is sectional drawing enlarged view of the BB' portion of FIG. It is a top view which shows an example of the structure of the carrier for double-sided polishing which concerns on 2nd Embodiment of this invention. It is sectional drawing enlarged view of the CC' portion of FIG. It is a top view which shows an example of the structure of the conventional double-sided polishing carrier. It is an enlarged view of a part P1 of FIG. FIG. 7 is an enlarged cross-sectional view of the AA' portion of FIG. 7.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
[First Embodiment]
First, the first embodiment of the present invention will be described.
(Structure of carrier 11 for double-sided polishing)
FIG. 1 is a plan view showing an example of the configuration of the double-sided polishing carrier 11 according to the first embodiment of the present invention, and FIG. 2 is an enlarged view of a part P2 of FIG.

The double-sided polishing carrier 11 has a disk shape, and one or more holes 13 capable of holding the disk-shaped wafer 12 inside, and in the present embodiment, one hole 13 is formed, and a predetermined pitch is formed on the outer peripheral portion. The outer peripheral teeth 14 are formed in the above. The double-sided polishing carrier 11 is formed thinner than the wafer 12.

The hole 13 is formed in a substantially circular shape, and the center (hole center) C2 of the hole 13 is formed eccentrically with respect to the center (carrier center) C1 of the double-sided polishing carrier 11.

On the inner peripheral surface of the hole 13, a plurality of convex curved surfaces 13A protruding toward the center C2 of the hole, and in the present embodiment, 12 convex curved surfaces 13A are formed with the same size and the same pitch. Between the convex curved surfaces 13A, a plurality of concave curved surfaces 13B recessed so as to be separated from the center C2 of the hole, and in the present embodiment, 12 concave curved surfaces 13B are formed with the same size and the same pitch. That is, the inner peripheral surface of the hole 13 is configured by alternately connecting 12 convex curved surfaces 13A and 12 concave curved surfaces 13B with the same size and the same pitch.

The shape of each convex curved surface 13A may be, for example, an arc shape or a quadratic curve shape (elliptical arc shape, parabolic shape, hyperbola shape). 1 and 2 show that the shape of each convex curved surface 13A is arcuate by showing an extension line of the shape of each convex curved surface 13A by a two-dot chain line. In FIGS. 1 and 2, the black circles on the convex curved surface 13A indicate that the wafer 12 and the convex curved surface 13A are in point contact at this point (vertex). FIG. 1 shows that the center (wafer center) CW of the wafer 12 is slightly eccentric with respect to the hole center C2 of the hole 13 due to the point contact of the wafer 12 with the convex curved surface 13A by the two black circles. Shows. When the wafer 12 and the convex curved surface 13A come into point contact at two points, the frictional resistance is increased and the rotation motion of the wafer 12 is promoted.

Here, in the present embodiment, the diameter HL1 of the virtual circle formed by the virtual line VL connecting the vertices of each convex curved surface 13A in a circular shape has a circular shape having a size that allows the wafer 12 to stay. It is formed.

Each convex curved surface 13A is formed at a position that is rotationally symmetric with respect to the hole center C2. When each convex curved surface 13A has an arc shape, the center of the arc is located on the extension line of the line segment passing through the hole center C2 and the apex of the convex curved surface 13A. When each convex curved surface 13A has a quadratic curve, the axis of the quadratic curve coincides with the straight line passing through the hole center C2 and the apex of the convex curved surface 13A.

Each concave curved surface 13B is formed at a position that is rotationally symmetric with respect to the hole center C2.
Each concave curved surface 13B is arranged so that a space 15 having a gap such that when two adjacent convex curved surfaces 13A make point contact with the wafer 12 does not come into contact with the wafer 12. As shown in FIG. 3, which is an enlarged cross-sectional view taken along the line BB'in FIG. 2, the polishing pad 16 is less deformed than the conventional polishing pad 6 shown in FIG. 8 because the space 15 is narrow. Therefore, the upper edge of the outer peripheral portion 2A of the wafer is not cut into an R shape, and the wafer 12 can rotate smoothly in the hole 13. In addition, in FIG. 1 and FIG. 2, in order to help understanding of the present invention, the space 15 which is the gap between the hole 13 and the wafer 12 is exaggerated.

The two adjacent convex curved surfaces 13A have an angle θ1 formed by a straight line passing through the apex of one convex curved surface 13A and the hole center C2 and a straight line passing through the apex of the other convex curved surface 13A and the hole center C2 (FIG. 1). (See) is preferably formed at a position where the temperature is 10 ° or more and 72 ° or less. More preferably, the angle θ1 is 20 ° or more and 60 ° or less.

When the angle θ1 is less than 10 °, since the contact points of the wafer 12 and the two points are close to each other, the rotational drive is almost the same as the one-point contact, and the rotational drive force of the double-sided polishing carrier 11 is transmitted to the wafer 12. No increase in communication capacity is expected.

On the other hand, when the angle θ1 is larger than 72 °, the holding time of the wafer 12 at the same contact point becomes long, so that the wafer 12 may be locally damaged.

On the other hand, when the angle θ1 is 10 ° or more and 72 ° or less, the wafer 12 may be locally damaged due to the continuous transition of the contact points while improving the rotational drive transmission ability by the two-point contact. There is no.

The width (gap) of the space 15 is preferably 0.1% or more and 0.6% or less of the diameter WD of the wafer 12.
For example, in the double-sided polishing carrier 11 for polishing a wafer 12 having a diameter WD of 300 mm, the width (gap) of the space 15 is 0.3 to 1.8 mm.

When the width (gap) of the space 15 is less than 0.1%, the wafer 12 is fixed to the hole 13 and cannot rotate smoothly depending on the molding accuracy of the wafer 12 or the hole 13.

On the other hand, when the width (gap) of the space 15 is larger than 0.6%, the polishing pad is crushed by the load, and the upper edge of the outer peripheral portion 12A of the wafer is scraped into an R shape.

On the other hand, when the width (gap) of the space 15 is 0.1% or more and 0.6% or less, the polishing pad is not crushed by the load, so that the upper edge of the wafer outer peripheral portion 12A is cut into an R shape. The wafer 12 can rotate smoothly while being suppressed from being damaged.

The double-sided polishing carrier 11 may include a main body made of a metal material such as stainless steel or titanium, and an annular resin inserter arranged along the inner wall of the hole 13. The resin inserter can be made of a general resin. As the resin, for example, an aramid resin, a polyamide resin, a polyacetal resin, a polyvinyl chloride resin, a polypropylene resin, a polyvinylidene fluoride resin, a fluororesin and the like can be used.
The resin inserter preferably contains glass fiber. This makes it possible to increase the durability of the resin inserter. The glass fiber is preferably contained in a volume ratio of 10 to 60%.

The double-sided polishing carrier 11 may be formed by combining, for example, an epoxy resin, a phenol resin, a polyimide resin, a polyamide resin, or the like with glass fibers, carbon fibers, aramid fibers, or the like. In particular, in consideration of contamination and cost advantages, it is preferable to use a composite of epoxy resin and glass fiber. The glass fiber is preferably contained in a volume ratio of 10 to 60%. Further, the entire carrier 11 for double-sided polishing may be coated with DLC (Diamond-like Carbon).

(Wafer 12 polishing method)
Next, a method for polishing a wafer using the double-sided polishing carrier 11 having the above configuration will be described.
In this embodiment, a double-sided polishing device provided with a planetary gear mechanism is used. This double-sided polishing device includes a rotary surface plate having an upper surface plate and a lower surface plate, a sun gear provided at the center of the rotary surface plate, and an internal gear provided on the outer peripheral portion of the rotary surface plate. ..

A plurality of double-sided polishing carriers 11 are set on the upper surface of the lower platen of the double-sided polishing device, the outer peripheral teeth 14 are engaged with the internal gear and the sun gear of the double-sided polishing device, and the wafer 12 is inserted into each hole 13.
After positioning the upper surface plate directly above the lower surface plate, it is lowered and pressed, and both sides of the plurality of double-sided polishing carriers 11 are pressed between the upper surface plate and the lower surface plate to which the polishing pads are attached.

Next, when the internal gear and / or the sun gear are rotated while supplying the polishing liquid between the upper surface plate and the lower surface plate, each double-sided polishing carrier 11 revolves around the sun gear and at the same time. Performs a rotating planetary motion.
The wafer 12 rotatably inserted into the hole 13 of each double-sided polishing carrier 11 has two points at the vertices of the two convex curved surfaces 13A due to the movement of the double-sided polishing carrier 11 and the difference in rotational peripheral speed between the upper and lower surface plates. Make point contact.

When the outer peripheral surface of the wafer 12 makes point contact with two adjacent convex curved surfaces 13A at two points, the wafer 12 has a frictional resistance generated at the contact point between each vertex of the two convex curved surfaces 13A and the outer peripheral surface of the wafer 12. Based on the above, it rotates by receiving the rotational driving force of the double-sided polishing carrier 11. The wafer 12 further receives the same rotational driving force from the two convex curved surfaces 13A that come into contact with each other. The frictional resistance is larger than that in the case of point contact at one point. As a result, the wafer 12 receives substantially the rotational driving force from the double-sided polishing carrier 11 continuously, and rotates smoothly without causing abrupt fluctuations in rotation or impact.

Each convex curved surface 13A has an arc shape or a quadratic curve shape. Therefore, when the wafer 12 moves from a state of point contact with two adjacent convex curved surfaces 13A to a state of point contact with two adjacent convex curved surfaces 13A, the wafer 12 is moved to a state of point contact with two adjacent convex curved surfaces 13A. The outer peripheral surface of the above moves smoothly along the curved surface of each convex curved surface 13A.

Therefore, there is no possibility that the wafer 12 is locally damaged, and the wafer 12 maintains smooth rotation, so that the flatness of both sides of the wafer 12 is improved.

In the present embodiment, each concave curved surface 13B has a space 15 having a gap such that when two adjacent convex curved surfaces 13A make point contact with the wafer 12 during double-sided polishing of the wafer 12, the concave curved surface 13B does not come into contact with the wafer 12. (See FIGS. 1 and 2) are arranged so as to be formed. Since the gap is set to 0.1% or more and 0.6% or less of the diameter WD of the wafer 12, the space 15 is narrower than the space 5 of the conventional double-sided polishing carrier 1 shown in FIG. 7. Therefore, since the polishing pad is not crushed by its own weight, it is possible to prevent the upper edge of the outer peripheral portion 2A of the wafer from being scraped into an R shape.

(Effect of the first embodiment)
As described above, in the present embodiment, the double-sided polishing carrier 11 has a hole 13 for accommodating the wafer 12. A plurality of convex curved surfaces 13A protruding toward the hole center C2 and concave curved surfaces 13B recessed away from the hole center C2 are alternately formed on the inner peripheral surface of the hole 13. All of the convex curved surfaces 13A are formed with the same size and the same pitch, and all of the concave curved surfaces 13B are formed with the same size and the same pitch. Each convex curved surface 13A is formed in an arc shape or a quadratic curve shape, and the virtual line VL connecting the vertices of each convex curved surface 13A in a circular shape is configured to have a circular shape having a size that allows the wafer 12 to stay. Has been done. The two adjacent convex curved surfaces 13A are formed so as to make point contact with the wafer 12. Each concave curved surface 13B is arranged with a gap such that when two adjacent convex curved surfaces 13A make point contact with the wafer 12, they do not come into contact with the wafer 12.

With this configuration, the frictional resistance between the wafer 12 and the inner peripheral surface of the hole 13 can be increased, and the rotation motion of the wafer 12 can be promoted.

Further, as shown in FIG. 3, the polishing pad 16 hardly enters the space 15 formed by the concave curved surface 13B located on both sides of the convex curved surface 13A and the outer peripheral surface of the wafer 12. Therefore, it is possible to prevent the upper edge of the outer peripheral portion 12A of the wafer from being cut into an R shape.
Therefore, the wafer 12 can rotate smoothly in the hole 13, and both sides of the wafer 12 are polished with high flatness.

Further, in the present embodiment, the angle formed by the two lines connecting the two adjacent vertices of the convex curved surface 13A and the hole center C2 is formed to be 10 ° or more and 72 ° or less.

With this configuration, there is a possibility that the wafer 12 may be locally damaged due to the continuous transition of the contact points with the vertices of the two adjacent convex curved surfaces 13A while improving the rotational drive transmission capability by the two-point contact. do not have.

Further, in the present embodiment, the gap of the space 15 formed by the concave curved surface 13B located on both sides of the convex curved surface 13A and the outer peripheral surface of the wafer 12 is 0.1% or more and 0.6% of the diameter WD of the wafer 12. It is as follows.

With this configuration, as shown in FIG. 3, the polishing pad 16 hardly enters the space 15. Therefore, local deformation of the polishing pad due to the polishing load can be prevented, and the wafer 12 can rotate smoothly while suppressing the upper edge of the outer peripheral portion 12A of the wafer from being scraped into an R shape.

[Second Embodiment]
Next, a second embodiment of the present invention will be described.
(Structure of carrier 21 for double-sided polishing)
FIG. 4 is a plan view showing an example of the configuration of the double-sided polishing carrier 21 according to the second embodiment of the present invention.

Similar to the first embodiment, the double-sided polishing carrier 21 has one or more holes 23 which are disk-shaped and can hold the disk-shaped wafer 22 inside, and in this embodiment, one hole 23 is provided. The outer peripheral teeth 24 are formed at a predetermined pitch on the outer peripheral portion. The double-sided polishing carrier 21 is formed thinner than the wafer 22.

The hole 23 is formed in a substantially circular shape, and the center (hole center) C4 of the hole 23 is formed eccentrically with respect to the center (carrier center) C3 of the double-sided polishing carrier 21.

The inner peripheral surface of the hole 23 passes through the midpoint of each side of the regular polygon centered on the center C4 of the hole, and is composed of a curved surface equal to or larger than the inscribed circle IC of the regular polygon. FIG. 4 shows an example in which the polygon is a regular hexagon.

The diameter of the inscribed circle IC is configured to be larger than the diameter of the wafer 22 to the extent that the wafer 22 can stay in the hole 23. Therefore, the wafer center CW is slightly eccentric with respect to the hole center C4 (which is also the center of the inscribed circle IC) of the hole 23.

The inner peripheral surface of the hole 23 is composed of a face 23A which is a part of each side of the regular polygon and a concave curved surface 23B which connects the ends of the adjacent faces 23A. Further, the wafer 22 is configured to make point contact with the intermediate point of the two adjacent faces 23A. In FIG. 4, the two black circles on the facing 23A indicate that the wafer 22 and the facing 23A are in point contact at this point. The frictional resistance is increased by the point contact between the intermediate point of the two adjacent faces 23A and the wafer 22, and the rotation motion of the wafer 22 is promoted.

The concave curved surface 23B is a curved surface recessed so as to be away from the center C4 of the hole, and the facing 23A and the concave curved surface 23B are configured to be alternately connected with the same length, the same size, and the same pitch. Further, each concave curved surface 23B is arranged so as to form a space 25 having a gap such that when the intermediate point of two adjacent faces 23A and the wafer 22 make point contact, the wafer 22 does not come into contact with the wafer 22. .. The gap allows the wafer 22 to rotate smoothly in the hole 23, and the entire surfaces of the wafer 22 are polished with high flatness. In addition, in FIG. 4, in order to help understanding of the present invention, the gap between the hole 23 and the wafer 22 is exaggerated.

The regular polygon is preferably a regular pentagon or more and a regular hexadecagon or less. It is still preferable that the regular polygon is a hexagon or more and an octagon or less.
For example, when the regular polygon is a regular pentagon, the angle formed by the perpendicular line from the hole center C4 to one surface 23A and the perpendicular line from the hole center C4 to the other surface 23A in two adjacent faces 23A. θ2 (see FIG. 4) is 72 ° (= 360 ° / 5). When the regular polygon is a regular hexadecagon, the angle θ2 is 10 ° (= 360 ° / 36).

When the regular polygon has more angles than the regular hexadecagon, the contact points of the wafer 22 and the two points are close to each other, so that the contact points are almost the same as those of the one-point contact, and the rotational driving force of the double-sided polishing carrier 21 is applied. It is not expected that the rotational drive transmission capacity to be transmitted to the wafer 22 will increase.

On the other hand, when the regular polygon has a smaller number of angles than the regular pentagon, the holding time of the wafer 22 at the same contact point becomes long, so that local damage may occur.

On the other hand, when the regular polygon is a regular pentagon or more and a regular hexadecagon or less, the rotation drive transmission ability by two-point contact is improved, and the contact points are continuously changed to be local to the wafer 22. There is no risk of damage. The regular polygon is preferably a regular hexagon or more and a regular octadecagon or less.

The width (gap) of the space 25 is preferably 0.1% or more and 0.6% or less of the diameter WD of the wafer 22 as in the first embodiment.
For example, in the double-sided polishing carrier 21 for polishing a wafer 22 having a diameter WD of 300 mm, the width (gap) of the space 25 is 0.3 to 1.8 mm.

When the width (gap) of the space 25 is less than 0.1%, the wafer 22 is fixed to the hole 23 and cannot rotate smoothly depending on the molding accuracy of the wafer 22 or the hole 23.

On the other hand, when the width (gap) of the space 25 is larger than 0.6%, the polishing pad is crushed by the load, and the upper edge of the outer peripheral portion 22A of the wafer is scraped into an R shape.

On the other hand, when the width (gap) of the space 25 is 0.1% or more and 0.6% or less, the polishing pad is not crushed by the load, so that the upper edge of the wafer outer peripheral portion 22A is cut into an R shape. The wafer 22 can rotate smoothly while being suppressed from being damaged.

Similar to the double-sided polishing carrier 11, the double-sided polishing carrier 21 may be configured to include a main body made of a metal material and a resin inserter, or may be entirely made of a composite of a synthetic resin and fibers. Further, the entire carrier 21 for double-sided polishing may be coated with DLC.

(Wafer 22 polishing method)
Next, a method for polishing the wafer using the double-sided polishing carrier 21 having the above configuration will be described.
In the present embodiment, a general double-sided polishing device that causes the double-sided polishing carrier 21 to rotate only at a fixed position, for example, the device described in Japanese Patent Application Laid-Open No. 2012-1483839 is used. This double-sided polishing device is provided with a center gear in the center, and is provided with a plurality of rotation mechanisms that mesh with the outer peripheral teeth 24 in the circumferential direction. Each outer peripheral tooth 24 of the plurality of double-sided polishing carriers 21 is meshed with the center gear and the outer gear provided in each rotation mechanism. As a result, each rotation mechanism rotates and drives the corresponding double-sided polishing carrier 21 in a fixed position in cooperation with the center gear.

Based on the usage of the double-sided polishing device, the double-sided polishing carrier 21 on which the wafer 22 is set is sandwiched between the upper and lower polishing pads, and the upper and lower surfaces of the wafer 22 are polished at the same time while the double-sided polishing carrier 21 is rotated at a fixed position. do.

The wafer 22 rotatably inserted into the hole 23 of the double-sided polishing carrier 21 comes into point contact with the midpoint between the two facing 23A as the double-sided polishing carrier 21 rotates.
When the outer peripheral surface of the wafer 22 makes point contact with the midpoint of two adjacent faces 23A at two points, the wafer 22 is based on the frictional resistance generated at the contact point between the two faces 23A and the outer peripheral surface of the wafer 22. Then, it rotates by receiving the rotational driving force of the double-sided polishing carrier 21. The wafer 22 also receives the same rotational driving force from the two faces 23A that come into contact with it next. The frictional resistance is larger than that in the case of point contact at one point. As a result, the wafer 22 receives substantially the rotational driving force from the double-sided polishing carrier 21 continuously, and rotates smoothly without causing abrupt fluctuations in rotation or impact.

Therefore, there is no possibility that the wafer 22 is locally damaged, and the wafer 22 maintains smooth rotation, so that the flatness of both sides of the wafer 22 is improved.

In the present embodiment, each concave curved surface 23B is a space having a gap such that the intermediate point between two adjacent faces 23A and the wafer 22 do not come into contact with the wafer 22 during the double-sided polishing of the wafer 22. 25 (see FIG. 4) is arranged so as to be formed. The gap is 0.1% or more and 0.6% or less of the diameter WD of the wafer 22. Therefore, the space 25 is narrower than the space 5 of the conventional double-sided polishing carrier 1 shown in FIG. 7. Therefore, as shown in FIG. 5, which is an enlarged cross-sectional view taken along the line CC of FIG. 4, the space 25 is narrow, so that the polishing pad 26 has less deformation than the conventional polishing pad 6 shown in FIG. 8, and the space is small. It hardly gets into 25. Therefore, it is suppressed that the upper edge of the wafer outer peripheral portion 22A is cut into an R shape, and the wafer 22 is polished with a high flatness.

(Effect of the second embodiment)
As described above, in the present embodiment, the double-sided polishing carrier 21 has a hole 23 for accommodating the wafer 22. The inner peripheral surface of the hole 23 passes through the midpoint of each side of the regular polygon centered on the center C4 of the hole, and is composed of a curved surface equal to or larger than the inscribed circle IC of the regular polygon. The hole 23 is formed so that the wafer 22 is in point contact with the midpoint between two adjacent sides of each side of the regular polygon. Each concave curved surface 23B is formed with a gap such that the wafer 22 does not come into contact with the wafer 22 when the intermediate point of the two adjacent sides of the regular polygon and the wafer 22 make point contact.

With this configuration, the frictional resistance between the wafer 22 and the inner peripheral surface of the hole 23 can be increased, and the rotation motion of the wafer 22 can be promoted.

Further, the polishing pad 26 hardly enters the space 25 formed by the concave curved surface 23B located on both sides of the facing 23A and the outer peripheral surface of the wafer 22. Therefore, it is possible to prevent the upper edge of the outer peripheral portion 22A of the wafer from being cut into an R shape.
Therefore, the wafer 22 can rotate smoothly in the hole 23, and the entire surfaces of the wafer 22 are polished with high flatness.

Further, in the present embodiment, the regular polygon is a regular pentagon or more and a regular hexadecagon or less. That is, the two adjacent faces 23A are located at positions where the angle between the vertical line from the hole center C4 to one face 23A and the vertical line from the hole center C4 to the other face 23A is 10 ° or more and 72 ° or less. It is formed.

With this configuration, there is a possibility that the wafer 22 may be locally damaged due to the continuous transition of the contact points with the intermediate points of the two adjacent faces 23A while improving the rotational drive transmission capability by the two-point contact. do not have.

Further, in the present embodiment, the gap of the space 25 formed by the concave curved surface 23B located on both sides of the facing 23A and the outer peripheral surface of the wafer 22 is 0.1% or more and 0.6% or less of the diameter WD of the wafer 22. Is.

With this configuration, as shown in FIG. 5, the polishing pad 26 hardly enters the space 25. Therefore, the wafer 22 can rotate smoothly while suppressing the upper edge of the wafer outer peripheral portion 22A from being scraped into an R shape.

[Other embodiments]
Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and there are design changes and the like within a range that does not deviate from the gist of the present invention. Even included in the present invention.

For example, in each of the above-described embodiments, the double-sided polishing carriers 11 and 21 show an example in which one hole 13 and 23 for holding the wafers 12 and 22 are formed therein, but the present invention is not limited thereto. The double-sided polishing carriers 11 and 21 may be formed with two or more holes 13 and 23 for holding the wafers 12 and 22 inside.

In the first embodiment, a double-sided polishing device provided with the planetary gear mechanism is used, and in the second embodiment, an example of using the double-sided polishing device provided with the rotating mechanism is shown, but the present invention is not limited thereto. In the first embodiment, the double-sided polishing device provided with the rotation mechanism may be used, and in the second embodiment, the double-sided polishing device provided with the planetary gear mechanism may be used.

1,11,21 ... Carrier for double-sided polishing, 2,12,22 ... Wafer, 2A, 12A, 22A ... Wafer outer periphery, 3,13,23 ... Hole, 3A ... Convex surface, 3B ... Concave, 4,14,24 ... Outer teeth, 5,15,25 ... Space, 6,16,26 ... Polishing pad, 13A ... Convex curved surface, 13B, 23B ... Concave curved surface, 23A ... Face, C1, C3 ... Carrier center, C2, C4 ... Hole center , CW ... Wafer center, HL1 ... Diameter of virtual circle formed by virtual line, HL2 ... Inscribed circle IC diameter, IC ... Inscribed circle, VL ... Virtual line, WD ... Wafer diameter, θ1, θ2 ... Angle ..

Claims (7)

A disk-shaped double-sided polishing carrier having holes for accommodating disk-shaped wafers.
A plurality of convex curved surfaces protruding toward the center of the hole and concave curved surfaces recessed away from the center of the hole are alternately formed on the inner peripheral surface of the hole.
All of the convex curved surfaces are formed with the same size and the same pitch.
All of the concave curved surfaces are formed with the same size and the same pitch.
Each of the convex curved surfaces is formed in an arc shape or a quadratic curve shape.
The virtual line connecting the vertices of each convex curved surface in a circular shape is configured to have a circular shape having a size that allows the wafer to stay.
The two adjacent convex curved surfaces are formed so as to make point contact with the wafer.
Each of the concave curved surfaces is a carrier for double-sided polishing, which is arranged with a gap such that when the two adjacent convex curved surfaces make point contact with the wafer, the concave curved surface does not come into contact with the wafer. In the double-sided polishing carrier according to claim 1,
A double-sided polishing carrier formed so that the angle formed by the two lines connecting each of the two adjacent vertices of the convex curved surface and the center of the hole is 10 ° or more and 72 ° or less. In the double-sided polishing carrier according to claim 1 or 2.
A carrier for double-sided polishing in which the gap is 0.1% or more and 0.6% or less of the diameter of the wafer. A disk-shaped double-sided polishing carrier having holes for accommodating disk-shaped wafers.
The inner peripheral surface of the hole passes through the midpoint of each side of the regular polygon and is composed of a curved surface equal to or larger than the inscribed circle of the regular polygon.
The hole is formed so that the wafer is in point contact with the intermediate point of two adjacent sides of each side of the regular polygon.
The curved surface is a double-sided polishing carrier formed with a gap such that when the wafer comes into point contact with the intermediate point of two adjacent sides of each of the regular polygons, the wafer does not come into contact with the wafer. In the double-sided polishing carrier according to claim 4,
The regular polygon is a carrier for double-sided polishing having a regular pentagon or more and a regular hexadecagon or less. In the double-sided polishing carrier according to claim 4 or 5.
A carrier for double-sided polishing in which the gap is 0.1% or more and 0.6% or less of the diameter of the wafer. A wafer polishing method for polishing both sides of a wafer by using the double-sided polishing carrier according to any one of claims 1 to 6.

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