JPH10202511A - Both side polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To polish a wafer uniformly by giving a carrier a circular motion with no self-rotation within a plane parallel to an surface of the carrier, and moving a work retained between upper and lower surface plates while turning in the through hole of the carrier. SOLUTION: If the rotational movement of an upper surface plate 14 and a lower surface plate 16, and the circular motion with no self-rotation of a carrier 12 are conducted concurrently, a wafer 10 is retained so as to be capable of rotating in a through hole 12a. Especially, if a difference is made between the absolute values of the rotational speed of the upper surface plate 14 and that of the lower surface plate 16 (the rotational speed of one surface plate is made larger than that of the other surface plate), the wafer 10 rotates together in the rotational direction of the surface plate whose rotational speed is higher, that is, the wafer 10 rotates in a prescribed direction. As a result of self-rotation of the wafer 10 its peripheral velocity increases more as it goes toward its outer periphery more at the upper surface plate 14 or the lower surface plate 16, however, the influence of the result can be eliminated, thus it is possible to polish the wafer 10 uniformly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a double-side polishing apparatus. Conventionally, as a double-side polishing apparatus, a processing material (hereinafter, referred to as a "work") is formed by rotating an external gear (hereinafter, referred to as an "external gear") and an internal gear (hereinafter, referred to as an "internal gear") at different angular velocities. The carrier corresponding to the planetary gear carrying the carrier is rotated and revolved, and the upper and lower platens having polishing surfaces disposed above and below the carrier sandwich the work from above and below and move relatively to the work. There is a type using a planetary gear mechanism for polishing by polishing. This double-side polishing device is used as a lapping device (lapping machine) or a polishing device. It has high accuracy and can simultaneously polish both surfaces, so that the processing time is short, and thin material polishing such as a silicon wafer used as a semiconductor chip material is performed. Suitable for.

[0002]

2. Description of the Related Art The structure of a polishing apparatus using a conventional planetary gear mechanism will be described with reference to FIG. 11
An upper surface plate 2 and a lower surface plate 114 are provided with a polishing cloth on each surface, and a polishing surface is formed by the polishing cloth. 116 is an external gear, and 118 is an internal gear. Reference numeral 120 denotes a carrier, and this carrier 1
The work 121 is held in a through hole formed in the inner gear 20, and rotates by meshing with the outer gear 116 and the inner gear 118. The upper stool 112 is connected to an upper stool 112a, and a gear 112c is provided at a tip of a shaft 112b hanging from the upper stool 112a. The gear 112c is an idle gear 112d, and the idle gear 112d is a gear 11
2e. The gear 112 e is provided coaxially with the spindle 126 so as to rotate integrally with the spindle 126. The lower platen 114 is driven by a spindle 114 via a gear 114 a provided coaxially with the lower platen 114.
6 is connected to a gear 114b coaxially provided. The external gear 116 is connected to a transmission gear 116b provided coaxially with the spindle 126 via a gear 116a provided coaxially with the external gear 116. The internal gear 118 is
The transmission gear 11 provided coaxially with the spindle 126 via a gear 118a provided coaxially with the internal gear 118.
8b. That is, this polishing apparatus uses one driving device to drive the external gear 116 and the internal gear 1.
18, a so-called four-way drive system for rotatingly driving the upper and lower platens 112 and 114. Note that the spindle 126 is connected to a variable speed reducer 132, and the variable speed reducer 132 is connected to a motor 134 via a belt 136, and controls the rotation speed of the spindle 126.

According to the polishing apparatus using the planetary gear mechanism, for example, the gear 116 is designed so that the angular velocity of the internal gear 118 is larger than the angular velocity of the external gear 116.
When the rotation ratio between the transmission gear 116a and the transmission gear 116b and the rotation ratio between the gear 118a and the transmission gear 118b are set, respectively, the carrier 120 meshed between the external gear 116 and the internal gear 118 rotates in the rotation direction of the internal gear 118. Revolve in the same direction (for example, "counterclockwise") and rotate clockwise. The lower platen 114 also rotates counterclockwise, while the upper platen 112 rotates clockwise due to the presence of the idle gear 112d. Note that the rotation direction and rotation speed of the carrier 120 can be changed by setting the angular velocities of the external gear 116 and the internal gear 118 according to the polishing conditions. Further, a liquid abrasive containing a slurry or the like is supplied to the front and back polishing surfaces of the work 121, and the work of the liquid 121 is suitably polished by the action of the liquid abrasive. According to this polishing apparatus, since the carrier 120 can be moved in a complicated manner, the work 121 (for example, a silicon wafer) can be uniformly polished while preventing uneven polishing. Therefore, the flatness of the work can be improved. Further, since both surfaces of the work 121 can be simultaneously polished, the polishing efficiency can be improved.

[0004]

However, in a conventional double-side polishing apparatus using a planetary gear mechanism, the carrier 12 is not used.
Since 0 is moved between the external gear 116 and the internal gear 118, it is difficult to cope with the recent enlargement of the work 121 such as a silicon wafer. That is, it is impossible to make the diameter of the carrier 120 larger than the radius of the platen,
There was a problem that the polished surface of the surface plate could not be used efficiently. In addition, in a conventional double-side polishing apparatus using a planetary gear mechanism, a complicated gear mechanism is used, and it is difficult to increase the size of the apparatus. There was a problem that costs increased in various aspects.

Accordingly, an object of the present invention is to improve the flatness of a wafer by preventing uneven polishing of the wafer,
An object of the present invention is to provide a double-sided polishing apparatus that can efficiently use a polished surface of a surface plate in a manner suitable for increasing the size of a work, does not complicate the configuration, and can reduce manufacturing costs.

[0006]

To achieve the above object, the present invention has the following arrangement. That is, the present invention
A carrier having a thin plate provided with a through-hole, and an upper and lower platen for sandwiching a plate-shaped work arranged in the through-hole of the carrier from above and below and relatively moving and polishing the work. In a double-side polishing apparatus comprising:
A circular motion that does not rotate in a plane parallel to the plane of the carrier, and the wire held between the upper and lower platens in the through hole.
A carrier circular motion mechanism for turning the tool.

[0007] The carrier circular motion device may further include a carrier holder for holding the carrier, a holder-side shaft parallel to the axis of the upper and lower platens and axially mounted on the carrier holder, and a holder-side shaft. A carrier-side shaft which is parallel to and is fixed to the base at a predetermined distance, and does not rotate the carrier holder with respect to the base by rotating the holder-side shaft about the base-side axis. Equipped with an eccentric arm that makes a circular motion, and a rotation driving device that rotates the eccentric arm about an axis on the base side,
With a simple configuration, it is possible to make the carrier held by the carrier holder perform a circular motion that does not rotate properly.

Further, a plurality of the eccentric arms are provided, and the plurality of eccentric arms are connected to each other by a synchronization means such as a timing chain so that the plurality of eccentric arms are circularly moved synchronously. With this configuration, the carrier can be appropriately and stably moved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a perspective assembly view schematically showing one embodiment of a double-side polishing apparatus according to the present invention, and FIG. 2 is a side sectional view showing the positional relationship of each component when the embodiment of FIG. 1 is operating. FIG. The present embodiment is a double-side polishing apparatus for polishing a silicon wafer 10 which is a plate-shaped work. The carrier 12 has a through-hole 12a formed in a thin plate, and is disposed in the through-hole of the carrier 12. Upper and lower platens 14, 16 for holding the wafer 10 from above and below and moving it relative to the wafer 10 for polishing.
And A polishing cloth 14a, 16a is attached to each surface of the upper and lower platens 14, 16, and a polishing surface is formed by the polishing cloth 14a, 16a. The wafer 10 has a circular shape and is loosely fitted in the circular through hole 12a, and has a size capable of rotating freely in the through hole 12a.

Reference numeral 20 denotes a carrier circular motion mechanism which causes the carrier 12 to make a circular motion that does not rotate in a plane parallel to the plane of the carrier 12, and that the upper platen 14 and the lower platen 16 in the through hole 12a.
The wafer 10 held between them is turned. The carrier circular motion mechanism 20 has the following configuration. Reference numeral 22 denotes a carrier holder, which is formed in a ring shape and includes a ring main body 22a and a holding ring 22b. The outer edge of the circular carrier 12 is sandwiched between the ring main body 22a and the holding ring 22b, and the carrier 12 is held by the carrier holder 22.

Reference numeral 24 denotes an eccentric arm, which is an upper and lower platen 1
A shaft 24a on the holder side which is parallel to the axis L of 4 and 16 and is axially mounted on the carrier holder 22, and a base 3 which is parallel to the shaft 24a on the holder side and at a predetermined distance.
0 (see FIG. 2). That is, it is formed to have the same function as the crank arm of the crank mechanism. This eccentric arm 2
In this embodiment, reference numerals 4 are arranged at four positions between the base 30 and the carrier holder 22 to support the carrier holder 22 and to rotate the holder-side shaft 2 around the base-side shaft 24b.
By rotating 4a, the carrier holder 22 makes a circular motion that does not rotate with respect to the base 30. The holder-side shaft 24a is rotatably inserted and axially mounted on a bearing portion 22c provided on the outer peripheral surface of the carrier holder 22 so as to project therefrom. As a result, the carrier 12 has upper and lower platens 14,
Turn with eccentricity M from 16 axis L (circular motion that does not rotate)
I do. The radius of the circular motion is the same as the distance between the shaft 24a on the holder side and the shaft 24b on the base side (distance of the eccentricity M), and all the points of the carrier 12 are in the motion of drawing the same small circle locus. .

Reference numeral 28 denotes a timing chain,
Each eccentric arm 24 is wound around a sprocket 25 (four in this embodiment) fixed coaxially to a shaft 24b on the base side of the eccentric arm 24. The timing chain 28 and the four sprockets 25 constitute a synchronizing means for connecting and synchronizing the four base-side shafts 24b so that the four eccentric arms 24 make a circular motion in synchronization. This synchronizing means has a simple configuration, and allows the carrier 12 to move favorably and stably. As a result, the polishing accuracy can be improved, and the flatness of the wafer can be improved. The synchronizing means is not limited to the present embodiment, but may be a timing chain or a gear. 32
Is a motor (for example, a gear motor), and 34 is an output gear fixed to an output shaft. The output gear 34 meshes with a gear 26 fixed coaxially to a shaft 24 b of the eccentric arm 24 on the base side. As a result, a rotation driving device that rotates the eccentric arm 24 about the shaft 24b on the base side is configured.

Incidentally, the rotary drive device is provided with each eccentric arm 24.
It is also possible to use a plurality of motors (for example, electric motors) arranged in correspondence with the above. In the case of an electric motor, a plurality of eccentric arms 24 can be electrically synchronized.
And the carrier 12 can be moved smoothly. In this embodiment, the eccentric arm 24 is
Although the case where a plurality of eccentric arms 24 are provided has been described, the present invention is not limited to this. If at least three eccentric arms 24 are provided, the carrier holder 22 can be suitably supported. Further, if the moving body of the XY table capable of obtaining a two-dimensional motion by combining the linear motions of the two orthogonal axes and the carrier holder 22 can be moved integrally, the movement of one eccentric arm 24 can be improved. By driving, the carrier holder 2
2 can make a circular motion without rotation. That is,
The moving body makes a non-rotational movement by being guided by guides extending in two orthogonal axes of the XY table, and the movement of the moving body is preferably used for the movement of the carrier holder 22 (circular movement that does not rotate). Available. Also,
Without using the eccentric arm 24, using (controlling) a driving mechanism of an XY table, for example, a servomotor provided on each of the X-axis and the Y-axis and a driving mechanism including a timing chain or a ball screw, enables the moving body to be moved. The integrated carrier holder 22 can also be moved (circular movement that does not rotate). In this case, two motors are used. By controlling the motors, various two-dimensional motions that do not rotate can be obtained in addition to the circular motion, and the motions are used for polishing the wafer 10. it can.

Reference numeral 36 denotes a lower platen rotating motor, which is a power unit for rotating the lower platen 16. For example, as in the present embodiment, a geared motor can be used, and its output shaft may be directly connected to the rotation shaft of the lower stool 16. Numeral 38 is a power means for rotating the upper stool, which rotates the upper stool 14.
Lower platen rotating motor 36 and upper platen rotating power means 3
8 can flexibly cope with various polishing specifications as long as the rotation direction and the rotation speed can be freely changed. Also,
In this double-side polishing apparatus, the wafer 10 disposed in the through hole 12a of the carrier 12 is moved to the upper platen 14 as shown in FIG.
Then, the lower platen 16 forms a sandwich, and the wafer is polished. At this time, the force for clamping the wafer 10 is mainly generated by a pressing means (not shown) provided on the upper surface plate 14 side. For example, the upper platen 14 may be pressed against the wafer 10 by an air bag system using air pressure. By controlling the air pressure, the pressing force can be adjusted appropriately and easily. In addition to the pressing means, an elevating device 40 for moving the upper surface plate 14 up and down is provided on the upper surface plate 14 side, and operates when the wafer 10 is supplied and discharged.

Next, a method of using the present invention will be described. First, the upper platen 14 is moved without moving the carrier 12.
The case where the absolute value of the rotation speed is the same but the lower platen 16 and the lower platen 16 are rotated in opposite directions will be described. That is, as shown in FIG. 1, for example, the upper surface plate 14 is rotated clockwise, and the lower surface plate 16 is rotated counterclockwise. In this case, since frictional forces act in completely opposite directions, the kinetic forces cancel each other out, and the two surfaces are polished theoretically with the wafer 10 stopped. However, in this case, the peripheral speeds of the upper stool 14 and the lower stool 16 increase toward the outer periphery. Therefore, the upper and lower platens 14, 16 of the wafer 10
Polishing is promoted in a portion farther from the portion corresponding to the axis L, and the wafer 10 is not uniformly polished.

Next, a description will be given of the polishing action by causing the carrier 12 to make a circular motion without rotating by the motion mechanism having the above-described configuration. Upper and lower surface plates 14, 16
When only the non-rotating circular motion of the carrier 12 is considered without considering the rotation of the carrier 12, the same motion is performed at all points of the moving member (carrier 12) according to the non-rotating circular motion. . This is a kind of oscillating motion in the sense that all points are the same motion, and it can be considered that the trajectory of the oscillating motion is a circle. Therefore, if the wafer 10 is swiveled via the carrier 12 which does not rotate and moves in a circular motion, the operation of the wafer
0 are uniformly polished.

When the rotational movement of the upper platen 14 and the lower platen 16 and the non-rotating circular movement of the carrier 12 are simultaneously operated, the wafer 10 is rotatably held in the through hole 12a. Therefore, in particular, the upper surface plate 14 and the lower surface plate 16
When the absolute value of the rotation speed of the base plate is different (when the rotation speed of the other base plate is increased with respect to one base plate), the wafer 10 is moved in the rotation direction of the base plate having the higher rotation speed. Go around. That is, the wafer 10 rotates in a predetermined direction. As the wafer 10 rotates in this manner, the peripheral speed of the upper platen 14 and the lower platen 16 increases toward the outer periphery, but the influence can be eliminated, and the wafer 10 can be uniformly polished. it can.
In order to uniformly polish both surfaces of the wafer 10, the upper platen 14 and the lower platen 16 may be alternately rotated so that one of them becomes faster.

Next, another method of using the present invention will be described. In the above embodiment, the case where a plurality of through holes 12a are provided and a plurality of works (wafers 10) are polished simultaneously has been described. However, the present invention is not limited to this. Hole 1 to be retained
Only one 2a is provided, and it can also be used as a polishing device for polishing both sides of a large work. In addition, as a large-sized work, there is a work such as a rectangular glass plate used for liquid crystal, or a wafer (circular) processed by a single wafer. In this case, the large work is arranged almost entirely from the center of the carrier 12 to the vicinity of the periphery thereof.
At this time, polishing is performed mainly by using circular motion that does not rotate by the carrier 12, and the rotation speed of the upper stool 14 and the lower stool 16 is reduced to such a degree that polishing unevenness does not occur. And it can grind suitably. That is, in the upper stool 14 and the lower stool 16, the polishing effect becomes larger toward the outer periphery due to the difference in the peripheral speed. However, if the rotation speed is much slower than the non-rotating circular motion of the carrier 12,
It can be hardly directly involved in the polishing action. The rotation of the upper platen 14 and the lower platen 16 constantly updates the surface of the platen in contact with the work, and improves the polishing action, such as supplying the liquid abrasive to the entire surface of the work evenly. Indirectly, it can suitably contribute.

Although the above embodiment has been described with reference to a polishing apparatus, the present invention can of course be suitably applied to a lapping apparatus. As described above, the present invention has been described variously with reference to preferred embodiments. However, the present invention is not limited to the embodiments, and it is needless to say that many modifications can be made without departing from the spirit of the invention. That is.

[0020]

According to the double-side polishing apparatus of the present invention, the carrier is caused to make a circular motion that does not rotate in a plane parallel to the plane of the carrier by the carrier circular motion mechanism, so that the carrier is vertically moved within the through hole of the carrier. The work held between the boards is swiveled. According to the circular motion that does not rotate, the same motion is performed in all portions of the carrier, so that the wafer can be uniformly polished, and the entire surface of the carrier and the polished surfaces of the upper and lower platens can be used efficiently. For this reason, it is possible to prevent unevenness in polishing of the wafer and improve the flatness of the wafer, and it is possible to efficiently use the polished surface of the platen in order to suitably cope with the enlargement of the work. Further, as compared with a double-side polishing apparatus using a conventional planetary gear mechanism, the configuration is not complicated, and the configuration can suitably cope with an increase in size. This has a remarkable effect that the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective assembly diagram of an embodiment of a double-side polishing apparatus according to the present invention.

FIG. 2 is a side sectional view of the embodiment of FIG.

FIG. 3 is a side sectional view illustrating a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Wafer 12 Carrier 12a Through-hole 14 Upper surface plate 16 Lower surface plate 20 Carrier circular motion mechanism 22 Carrier holder 24 Eccentric arm 24a Holder side shaft 24b Base side shaft 28 Timing chain 30 Base

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Haruo Sumizawa 1650 Kiyono, Matsushiro-machi, Nagano City, Nagano Prefecture, Fujikoshi Machinery Co., Ltd.

Claims (3)

[Claims] 1. A carrier in which a thin plate is provided with a through-hole, and a plate-like work arranged in the through-hole of the carrier are sandwiched from above and below, and are moved relatively to the work to polish the work. In the double-side polishing apparatus having upper and lower platens, the carrier is caused to make a circular motion that does not rotate in a plane parallel to the surface of the carrier, and is held between the upper and lower platens in the through hole. A double-side polishing apparatus comprising a carrier circular motion mechanism for rotating a work. 2. The carrier circular motion mechanism includes: a carrier holder that holds the carrier; a holder-side shaft parallel to an axis of the upper and lower platens and axially mounted on the carrier holder; and a holder-side shaft. A carrier-side shaft which is parallel to and is fixed to the base at a predetermined distance, and does not rotate the carrier holder with respect to the base by rotating the holder-side shaft about the base-side axis. 2. The double-side polishing apparatus according to claim 1, further comprising: an eccentric arm that makes a circular motion; and a rotation drive device that rotates the eccentric arm about an axis on the base side. 3. A plurality of eccentric arms are provided, and the plurality of eccentric arms are connected to each other by a synchronization means such as a timing chain so that the axes on the base side are linked to each other so that the plurality of eccentric arms circularly move synchronously. The double-side polishing apparatus according to claim 2.