JP3230551U - Wafer polishing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer polishing apparatus capable of solving a problem of poor polishing of a wafer attached to a center position of a holding plate and a problem of variation in the finished state of the wafer for each holding plate. SOLUTION: A wafer polishing device 1 is a device that grinds a wafer attached to a holding plate 20 by sliding contact with a revolving platen 10, and swings the platen 10 in a predetermined direction in a revolving surface. The swing mechanism 16 to move, the top ring 30 that applies a load to the holding plate 20 and applies a rotational force, the drive shaft 38 that rotationally drives the top ring 30, and the drive shaft 38 are rotatably suspended and supported. A support member 62 and a vertical movement mechanism 52 that moves the drive shaft 38 and the top ring 30 up and down by moving the support member 62 up and down are provided, and the drive shaft 38 includes deep groove ball bearings, spacers, and double bearings from bottom to top. It is configured to be supported by the support member 62 via a bearing mechanism arranged in the order of row conical roller bearings. [Selection diagram] Fig. 1

Description

The present invention relates to a wafer polishing device, and more particularly to a wafer polishing device that grinds a wafer attached to a holding surface of a holding plate by sliding it on a revolving surface plate.

As one of the steps of manufacturing a semiconductor device or the like, there is a step of polishing a wafer (silicon wafer or the like). As an example of a wafer polishing device used in the process, a device has been developed that polishes the wafer by sliding the wafer on the holding surface of the holding plate under pressure. Patent Document 1: See JP-A-2019-121682).

Japanese Unexamined Patent Publication No. 2019-121682

In the conventional wafer polishing apparatus exemplified in Patent Document 1, a holding plate to which a wafer is attached is held on a surface plate so as to be rotatable by a center roller and a guide roller, and the holding plate is pressed by a top ring. It is configured to be polished. Here, since the polishing cloth is attached to the upper surface of the surface plate, it is difficult for the holding plate to rotate, which plays an important role in the polishing process. Therefore, the top ring is rotationally driven to assist the rotation of the holding plate. It has become.

However, in the above-mentioned wafer polishing apparatus, when polishing a wafer, the polishing action due to the rotation of the holding plate is smaller in the wafer attached to the center position of the holding plate than in the wafer at the peripheral position, so that the surface to be polished has a surface to be polished. There is a problem that polishing defects such as streaks remain are likely to occur.

Further, the above-mentioned wafer polishing apparatus has a configuration in which each drive shaft is independently rotatably and vertically movable so that a plurality of top rings provided can be used for polishing independently. .. But There is a problem that a slight difference in the rotation speed occurs for each holding plate, and the finished state of the wafer to be polished may vary.

The present invention has been made in view of the above circumstances, and is caused by the problem that the wafer attached to the center position of the holding plate is poorly polished and the non-uniform frictional force of the drive shafts provided on the plurality of top rings. It is an object of the present invention to realize a wafer polishing apparatus capable of solving both the problem that the finished state of the wafer varies depending on the holding plate.

The present invention solves the above-mentioned problems by means of a solution as described below as an embodiment.

The wafer polishing device according to the present invention is a wafer polishing device that grinds a wafer attached to a holding surface of a holding plate by sliding contact with a rotating platen, and the platen is placed in a predetermined direction in the rotating surface. A swing mechanism that swings the top ring, a top ring that applies a load to the holding plate and applies a rotating force, a drive shaft that is connected to the top ring and rotationally drives the top ring, and the drive shaft. A support member that rotatably suspends and supports the support member and a vertical movement mechanism that moves the drive shaft and the top ring up and down by moving the support member up and down are provided, and the drive shaft has a deep groove from bottom to top. It is required that the bearing is supported by the support member via a bearing mechanism arranged in the order of a ball bearing, a spacer, and a double-row conical roller bearing.

According to the present invention, the revolving surface plate can be swung in a predetermined direction. Therefore, more polishing action can be generated on the wafer at the center position of the holding plate, and the occurrence of polishing defects can be prevented. Further, in the device configuration for swinging the surface plate, the top ring can be hung and supported in a stable and rotatable manner, and the frictional force of the drive shaft can be made uniform with respect to a plurality of top rings. It is possible to prevent variations in the polishing finish.

It is a perspective view which shows the example of the wafer polishing apparatus which concerns on embodiment of this invention. FIG. 2 (a) is a schematic view of the holding surface of the holding plate to which the wafer to be polished is attached. FIG. 2 (a) shows the case where there is one wafer, and FIG. 2 (b) shows the case where there are three wafers. ) Is an example when the number of wafers is five. It is a perspective view which shows the example of the vertical movement mechanism and the rotation drive mechanism of the wafer polishing apparatus shown in FIG. It is a front sectional view around the bearing mechanism of the wafer polishing apparatus shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view (perspective view) showing an example of the wafer polishing apparatus 1 according to the embodiment of the present invention. Further, FIG. 2 is a schematic view (bottom view) of the holding surface 20a of the holding plate 20 to which the wafer W to be polished is attached. Further, FIG. 3 is a schematic view showing an example of the vertical movement mechanism 52 and the rotation drive mechanism 36 of the wafer polishing device 1 shown in FIG. 1, and FIG. 3A is a perspective view of the vertical movement mechanism 52 and the rotation drive mechanism 36. 3 (b) is a cross-sectional view of part X in FIG. 3 (a), FIG. 3 (c) is a cross-sectional view of part Y in FIG. 3 (a), and FIG. 3 (d) is in FIG. 3 (a). It is sectional drawing of Z part. Further, FIG. 4 is a schematic view (front sectional view) around the bearing mechanism 70 of the wafer polishing apparatus 1 shown in FIG. For convenience of explanation, the front-back, left-right, and up-down directions of the wafer polishing apparatus 1 may be described by arrows in the drawing. Further, in all the drawings for explaining each embodiment, members having the same function may be designated by the same reference numerals, and the description of the repetition thereof may be omitted.

In the wafer polishing apparatus 1 according to the present embodiment, one or a plurality of wafers (not particularly limited, but about 3 to 10 as a main example) wafers (disk-shaped silicon wafers, etc.) W are attached to the holding surface. The holding plate 20 is held on the surface plate 10 so as to be rotatable by the center roller 54 and the guide roller 56, and the surface plate 10 is rotated (revolved) while being pressed against the surface plate 10 by the top ring 30 to rotate (revolve) the wafer W. It is a device for polishing. In the present application, the rotation of the surface plate 10 may be referred to as "revolution", and the rotation of the holding plate 20 on the surface plate 10 may be referred to as "rotation".

First, the holding plate 20 has one or a plurality of wafers W attached to the holding surface 20a, and has an action of bringing the surface to be polished Wa of the wafer W into contact with the polished surface 10a of the surface plate 10. In the present embodiment, the wafer W is adhered to the holding surface 20a of the holding plate 20 by a known peelable adhesive. The holding plate 20 is required to have a high flatness accuracy and a material that is not easily deformed, and is generally formed of glass, ceramics, or the like.

Next, the surface plate 10 is formed in a circular shape in a plan view using a metal material (for example, a stainless alloy), and includes a polished surface (upper surface) 10a for polishing the wafer W. A holding plate 20 to which the wafer W is attached is placed on the polished surface 10a. The polishing step is usually carried out with a polishing pad (not shown) attached to the polishing surface 10a (therefore, the "polishing surface 10a" in the present application includes a state in which the polishing pad is attached. (Must be). Further, the surface plate 10 is rotated (rotated) about the axis by a rotation drive mechanism 50 including an electric motor. As an example, the rotation (rotation) speed of the surface plate 10 is set to about 20 rpm.

In the present embodiment, a swing mechanism 16 for swinging the surface plate 10 in a predetermined direction in the revolution plane is provided. As an example, it is configured to swing about 60 mm in the front-rear direction (may be another direction). According to this, the following effects can be obtained.

Specifically, as described above, the wafer polishing device 1 rotates the holding plate 20 to which one or more wafers W are attached while pressing the holding plate 20 against the surface plate 10 by the top ring 30. However, the wafer W is polished by revolving the surface plate 10. As a few examples, when the number of wafers W attached to the holding plate 20 is one, the wafers W are arranged as shown in FIG. 2A, and when there are a plurality of wafers (for example, three), FIG. ), And in the case of a plurality of sheets (for example, 5 sheets), 1 sheet is arranged at the center position in the radial direction and 4 sheets are arranged at the peripheral position as shown in FIG. 2C. Here, when the holding plate 20 is rotated, the speed (peripheral speed) of the central position is slower than that of the peripheral position. Therefore, the wafer W at the center position has a smaller polishing action due to the rotation of the holding plate 20 than the wafer W at the peripheral position. In particular, the central region of the surface to be polished Wa on the wafer W at the center position is more prominent in its influence, and polishing defects such as streaks remaining are likely to occur. In response to such a problem, according to the above configuration, the surface plate 10 can be revolved and swung in a predetermined direction. As a result, more sliding operations (that is, polishing actions) can be generated even on the wafer W at the center position of the holding plate 20, so that the occurrence of polishing defects can be prevented.

Next, the center roller 54 is arranged so as to be rotatable (rotating) at the radial center of the surface plate 10. The center roller 54 according to the present embodiment is not configured to generate a rotational force by itself, but is rotatably supported by a support shaft 40 and is arranged so that the outer peripheral surfaces of the center rollers 54 abut against the holding plate 20. Will be done.

Next, a plurality (for example, four) of guide rollers 56 are rotatably arranged on the outer edge of the surface plate 10 in the radial direction at predetermined intervals. Here, the guide roller 56 releases the position at which the holding plate 20 placed on the surface plate 10 with the wafer W attached to the holding surface 20a is sandwiched between the center roller 54 and the holding plate 20. It is provided so that it can be moved to and from the free position. The guide roller 56 according to the present embodiment is not configured to generate a rotational force by itself.

According to this configuration, the holding plate 20 placed on the surface plate 10 is held at a predetermined position sandwiched between the guide roller 56 and the center roller 54 (a predetermined position stationary with respect to the revolving surface plate 10). By positioning and pressing and rotating the top ring 30, which will be described later, the holding plate 20 can be rotated (rotated).

As an example, in each of the center roller 54 and the guide roller 56, the roller portion that abuts (transits) with the holding plate 20 is formed by using a resin material (as an example, POM resin). However, it is not limited to this.

Next, the top ring 30 is provided with a pressing portion (not shown) formed in a circular shape in a plan view at the lower end portion, and the polished surface of the surface plate 10 with the holding surface 20a of the wafer W held down. The holding plate 20 placed on the 10a is pressed from above, and the surface to be polished Wa of the wafer W and the surface to be polished 10a are brought into pressure contact with each other. The top ring 30 is configured to apply a load to the holding plate 20 and to apply a rotation force to the holding plate 20 by rotating in a state of being in pressure contact with the holding plate 20.

As an example, a weight is held inside the main body of the top ring 30 in a laminated state, and the wafer W is pressed against the surface plate 10 with a predetermined pressure via the holding plate 20. A disk-shaped weight using lead or the like can be used for this weight. However, the means for applying and pressing the load is not limited to this, and it is also possible to use the fluid pressure or the like by the cylinder device in place of or together with the weight (not shown).

Further, a drive shaft 38 connected to the top ring 30 to rotate the top ring 30 and a rotary drive mechanism 36 having a drive source (for example, an electric motor) 34 to rotate the drive shaft 38 are provided. Has been done. According to this, the rotation drive mechanism 36 can be driven to rotate the top ring 30 via the drive shaft 38. Therefore, the top ring 30 can be rotated while being in pressure contact with the holding plate 20 to apply a rotation force (assist rotation) to the holding plate 20.

Further, the drive shaft 38 and the top ring 30 are moved by moving the support member 62 that rotatably suspends and supports the drive shaft 38 and the support member 62 in the vertical direction (that is, in the direction of contacting and separating from the polishing surface 10a). It is configured to include a vertical movement mechanism 52 that moves the vehicle up and down. According to this, the vertical movement mechanism 52 can be driven to move the drive shaft 38 and the top ring 30 up and down via the support member 62. Therefore, the top ring 30 can be raised when the holding plate 20 to which the wafer W is attached is placed on the surface plate 10, and the top is formed when the holding plate 20 is pressed to polish the wafer W. The ring 30 can be lowered.

In the present embodiment, the vertical movement mechanism 52 and the support member 62 are arranged for each of the plurality of (for example, four) top rings 30 provided. As an example, the vertical movement mechanism 52 is configured to include an air cylinder 66 having a piston 68 that moves up and down, and a support member 62 is connected to the piston 68. According to this, since each drive shaft 38 can be hung and supported independently so as to be rotatable and vertically movable, a plurality of top rings 30 provided can be used in correspondence with polishing independently. Can be done.

On the other hand, when polishing using a plurality of top rings 30 at the same time, it is important to match the rotation speeds of the top rings 30. This is because if the speeds of the top rings 30 do not match, the rotation speeds of the holding plates 20 do not match, which causes variations in the finish of the wafer W to be attached and polished to each.

However, there is a problem that it is extremely difficult to accurately match the rotation speeds of the plurality of top rings 30. The reason for this is that in a configuration in which the drive shaft 38 is rotatably supported by the support member 62 via a bearing (bearing mechanism 70 described later), the support portion (the portion rotatably supported via the bearing) This is because it is extremely difficult to uniformly adjust the tightening force for supporting (fixing) (the tightening force in the configuration in which the bearing mechanism 70 is tightened by the annular tightening member 78). Even if there is a slight difference in the tightening force of the support portion in the plurality of support members 62, the frictional force during rotation (specifically, the sliding frictional force in the bearing mechanism 70) of the plurality of drive shafts 38 is not sufficient. It becomes uniform, and a slight difference in rotation speed occurs among the plurality of top rings 30, that is, the plurality of holding plates 20, which causes variations in the finished state of the wafer W to be polished.

In response to this problem, in the present embodiment, the drive shaft 38 is supported from the bottom to the top via a bearing mechanism 70 arranged in the order of the deep groove ball bearing 72, the spacer 74, and the double row tapered roller bearing 76. It is configured to be supported by the member 62. According to this, it is possible to solve the above-mentioned problems. That is, it becomes extremely easy to uniformly adjust the tightening force for supporting (fixing) the support portions for supporting the plurality of drive shafts 38 arranged on the support members 62 so as to be rotatable. Therefore, it is possible to prevent a slight difference in the rotation speed from occurring for each holding plate 20, and it is possible to prevent variations in the finished state of the wafer W to be polished.

Further, as described above, the wafer polishing device 1 includes a swing mechanism 16 that swings the surface plate 10. Due to this swing, a radial force (a force in the direction orthogonal to the rotation axis) acts on the drive shaft 38 via the top ring 30. This radial force acts as a force larger than the configuration in which the surface plate 10 simply revolves. Therefore, in the present embodiment, the support portion 64 is provided to receive the radial force and regulate the drive shaft 38 from moving in the radial direction. As a configuration example, the first support portion 64 (64A) and the second support portion 64 (64B) are provided at at least two positions on the drive shaft 38 which are separated by a predetermined distance in the axial direction. Here, the first support portion 64 (64A) is configured to include a spline mechanism (including a ball spline mechanism) that transmits the driving force of the drive source (electric motor) 34 to the drive shaft 38. According to this, the radial force acting on the drive shaft 38 due to the swing of the surface plate 10 is received, and the drive shaft 38 is prevented from being displaced in the radial direction, the axis center is tilted, and the like. It is possible to realize a configuration in which the drive shaft 38 can be rotated and moved up and down. In the present embodiment, the first support portion 64 (64A) is provided on the upper side and the second support portion 64 (64B) is provided on the lower side, but the configuration may be upside down (not shown).

Subsequently, an outline of the wafer polishing process using the wafer polishing apparatus 1 having the above configuration will be described. First, the guide roller 56 farthest in the surface plate rotation direction with respect to the holding plate supply position on the surface plate 10 is moved to the holding position of the holding plate 20. Next, the holding plate 20 supplied to the supply position is conveyed to a position where it is sandwiched between the center roller 54 and the farthest guide roller 56 by the rotation of the surface plate 10. Next, the holding plate 20 is continuously set by sandwiching the holding plate 20 between the guide roller 56 and the center roller 54, which are the second from the farthest in the same manner (as an example, a total of four sets are set).

Next, a plurality of wafers W (arranged as shown in FIG. 2C as an example) are pressed against the surface plate 10 by the top ring 30 via the holding plate 20, and the surface plate 10 is rotated (as an example). The wafer W is polished by revolving). Since the holding plate 20 is received by the center roller 54 and the guide roller 56, the holding plate 20 does not rotate (revolve) with the surface plate 10 but is rotated by the difference in peripheral speed between the center and the periphery of the surface plate 10. As a result, it is possible to simultaneously and evenly polish a plurality of wafers W.

Further, in the present embodiment, by driving the drive shaft 38, the top ring 30 pressed against the holding plate 20 is rotated, and a rotational force (rotational force) is applied to the holding plate 20. According to this, the holding plate 20 can be rotated reliably and at a stable speed (rotational speed). As an example, the rotation (rotation) speed of the top ring 30 is set to about 20 rpm so that the rotation (rotation) speed of the holding plate 20 is about the same as the rotation (revolution) speed of the platen 10 (about 20 rpm). ing.

Further, in this polishing step, a slurry (polishing liquid) is supplied to a portion where the surface to be polished Wa of the wafer W and the polishing surface 10a of the surface plate 10 are polished. This slurry contains fine abrasive grains and a chemical solution that can appropriately erode the wafer W, and by the action of both, the surface Wa to be polished of the wafer W can be polished so as to have a highly accurate mirror surface shape.

As described above, according to the present invention, the revolving surface plate can be swung in a predetermined direction. Therefore, more polishing action can be generated on the wafer at the center position of the holding plate, and the occurrence of polishing defects can be prevented. Further, in the device configuration for swinging the surface plate, the top ring can be hung and supported in a stable and rotatable manner, and the frictional force of the drive shaft can be made uniform with respect to a plurality of top rings. It is possible to prevent variations in the polishing finish.

The present invention is not limited to the examples described above, and various modifications can be made without departing from the present invention. For example, a wafer (silicon wafer) has been described as an example of an object to be polished, but the description is not limited to this, and the same applies to other flat plate-shaped (particularly disk-shaped) workpieces. Can be applied to.

1 Wafer polishing device 10 Surface plate 20 Holding plate 30 Top ring 36 Rotational drive mechanism 38 Drive shaft 40 Support shaft 52 Vertical movement mechanism 54 Center roller 56 Guide roller 62 Support members 64, 64A, 64B Support part 70 Bearing mechanism W Wafer

Claims (3)

A wafer polishing device that grinds a wafer attached to the holding surface of a holding plate by sliding it against a revolving surface plate.
A swing mechanism that swings the surface plate in a predetermined direction in the revolution plane,
A top ring that applies a load to the holding plate and applies a rotation force,
A drive shaft connected to the top ring and rotationally driving the top ring,
A support member that rotatably suspends and supports the drive shaft,
A vertical movement mechanism for moving the drive shaft and the top ring up and down by moving the support member up and down is provided.
Wafer polishing is characterized in that the drive shaft is supported by the support member via a bearing mechanism arranged in the order of a deep groove ball bearing, a spacer, and a double row tapered roller bearing from bottom to top. apparatus. As a support portion that receives a radial force acting on the drive shaft via the top ring due to the swing of the surface plate and regulates the radial movement, at least two parts of the drive shaft separated by a predetermined distance in the axial direction. The first support part and the second support part are provided at the position of the place,
The wafer polishing apparatus according to claim 1, wherein the first support portion includes a spline mechanism for transmitting a driving force of an electric motor to the driving shaft. A plurality of the top rings are arranged.
The vertical movement mechanism and the support member are arranged for each of the top rings.
The vertical movement mechanism is configured to include an air cylinder having a piston that moves up and down.
The wafer polishing apparatus according to claim 1 or 2, wherein the support member is connected to the piston.

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