JP6748440B2 - Grinding machine - Google Patents

Description

The present invention relates to a grinding device, and more particularly to a grinding device that grinds a wafer while feeding the grinding means toward a wafer along a roll axis parallel to the vertical direction.

In the field of semiconductor manufacturing, backside grinding is performed to grind the backside of a wafer in order to form a semiconductor wafer such as a silicon wafer (hereinafter referred to as “wafer”) into a thin film.

As a grinding device that grinds the back surface of a wafer, Patent Document 1 discloses a chuck that adsorbs and holds a wafer, a spindle that has a cup-shaped grindstone that grinds the wafer at its tip, and a grindstone feeder that cantilevers the spindle. Those equipped with are known. The grindstone feeding device elevates and lowers the spindle, and by lowering the spindle, the cup-shaped grindstone is pressed against the wafer and the back surface of the wafer is ground.

In such a grinding apparatus, as shown in FIG. 6, the cup-shaped grindstone 91 and the wafer W sucked and held by the wafer chuck 92 are offset from each other such that the yaw axis Y passes through the respective centers in a plan view. ing. The grinding area A2 in which the cup-shaped grindstone 91 grinds the wafer W is formed in an arc shape between the center O3 of the wafer W and the outer periphery of the cup-shaped grindstone 91.

JP, 2013-212571, A

However, in the grinding device described in Patent Document 1 as described above, the spindle 92 is firmly supported with respect to the rotation around the yaw axis Y, but has a weak supporting force with respect to the rotation around the pitch axis X. Due to the back force acting on the cup-shaped grindstone 91 during the grinding process, the cup-shaped grindstone 91 is likely to rotate about the pitch axis X, and the posture of the spindle 92 cannot be maintained parallel to the wafer W. There is a problem that the excessive force locally acts and the wafer W may be damaged.

Therefore, the technical problem to be solved arises that the posture of the grindstone during grinding is kept parallel to the wafer and the grinding of the wafer is performed with high quality. The purpose is to resolve.

The present invention has been proposed to achieve the above object, and the invention according to claim 1 includes a holding means capable of holding and rotating a wafer, a grinding means for grinding the wafer, and the grinding means. A grinding device comprising cantilever-supporting and feeding means for feeding the grinding means parallel to a vertical direction and feeding the wafer toward a wafer along a roll axis which is a central axis by which the grinding means can rotate. grinding region grinding means for grinding the wafer, across the yaw axis is passing Ri said grinding means rotatable around axis center of rotation of the grinding wheel of the grinding means in perpendicular to the roll axis in a plan view An arc-shaped inclination means for inclining the holding means in accordance with an inclination about a pitch axis which is a central axis through which the grinding means can rotate and which is perpendicular to the roll axis and the yaw axis, The tilting means is a fixed support portion arranged on a straight line that passes through the rotation center of the holding means when viewed in a plane and is substantially parallel to the pitch axis and on the opposite side of the rotation center of the holding means across the yaw axis. To provide a grinding device.

According to this configuration, since the grinding region is formed across the yaw axis, the pitching component of the grinding region that induces the rotation of the grinding means around the pitch axis is reduced, and the rotation of the grinding means around the pitch axis is suppressed. Therefore, the posture of the grinding means is maintained parallel to the wafer, and the wafer can be uniformly ground in the grinding region. Further, even when the grinding means cantilevered by the feeding means tilts due to its own weight, that is, when the grinding means tilts, the tilting means tilts the holding means in accordance with the tilting of the grinding means, so that the attitude of the grinding means is increased. Are maintained parallel to the wafer, so that the wafer can be ground with high quality.

According to a second aspect of the present invention, in addition to the configuration of the first aspect of the invention, a grinding device is provided in which the grinding region is arranged on the opposite side of the feed means with the center of rotation of the grindstone sandwiched therebetween in plan view. provide.

According to this configuration, in addition to the effect of the invention described in claim 1, in the case where the grinding region is arranged at the tip end side of the yaw axis, that is, the grinding region is arranged on the opposite side of the feed means with the center of rotation of the grindstone interposed therebetween. Where the grinding means and the feeding means are separated from each other and the grinding means is likely to rotate about the pitch axis, the grinding area is formed across the tip side of the yaw axis, so that the pitching component in the grinding area is reduced. Since the rotation of the grinding means around the pitch axis is effectively suppressed, the posture of the grinding means is maintained parallel to the wafer, and the wafer can be uniformly ground in the grinding area.

According to a third aspect of the present invention, in addition to the configuration of the first or second aspect of the invention, there is provided a grinding device in which the grinding region is formed symmetrically with respect to the yaw axis in plan view.

According to this configuration, in addition to the effect of the invention according to claim 1 or 2, since the grinding region is formed symmetrically with respect to the yaw axis, the pitching component of the grinding region is further reduced, and the grinding means Since the posture is maintained parallel to the wafer, the wafer can be uniformly ground in the grinding area.

According to a fourth aspect of the present invention, in addition to the configuration of the first aspect of the present invention, the grinding region has an arc shape from the center of the wafer toward the outer periphery of the wafer in plan view. A formed grinding device is provided.

According to this structure, in addition to the effect of the invention described in any one of claims 1 to 3, since the grinding area is formed so that the grinding means is pulled out to the outer periphery of the wafer, the edge chipping of the wafer is suppressed. be able to.

According to the present invention, since the grinding region is formed across the yaw axis, the pitching component of the grinding region that induces the rotation of the grinding means around the pitch axis is reduced, and the rotation of the grinding means around the pitch axis is suppressed. Therefore, the attitude of the grinding means is maintained parallel to the wafer, and the wafer can be uniformly ground in the grinding area.

The side view which shows the grinding device which concerns on one Example of this invention. The top view of the grinding device shown in FIG. FIG. 3 is a partial cross-sectional view taken along line I-I of FIG. 2 showing the internal structure of the tilting means and the holding means. The top view which shows the arrangement|positioning relationship of a grinding means and a chuck. The schematic diagram which shows a mode that a holding means is inclined according to the axis tilt of a grinding means. The top view which shows the arrangement|positioning relationship of the grinding means used with the conventional grinding means, and a wafer.

The grinding apparatus according to the present invention is capable of holding and rotating a wafer in order to achieve the purpose of maintaining the posture of the grindstone during grinding parallel to the wafer and performing high-quality grinding of the wafer. And a holding means, a grinding means for grinding the wafer, and a feeding means for supporting the grinding means in a cantilever manner and feeding the grinding means toward the wafer along a roll axis parallel to the vertical direction. The grinding area where the grinding means grinds the wafer is realized by being formed in an arc shape across the yaw axis which is perpendicular to the roll axis and which passes through the center of the grinding means in plan view.

Hereinafter, a grinding device 1 according to an embodiment of the present invention will be described with reference to the drawings. In the following examples, when referring to the number of components, numerical values, amounts, ranges, etc., unless otherwise specified or in principle limited to a specific number, the specific number The number is not limited and may be a specific number or more or less.

Also, when referring to the shapes and positional relationships of constituent elements, etc., unless otherwise specified, or in principle, it is considered that the shape and the like are substantially similar or similar to the shape, etc. Including.

In addition, in the drawings, characteristic portions may be exaggerated by enlarging the characteristic portions in order to make the characteristics easy to understand, and the dimensional ratios of the constituent elements are not always the same as the actual ones. Further, in the cross-sectional views, hatching of some components may be omitted in order to make the cross-sectional structure of the components easy to understand. In this embodiment, the terms "upper" and "lower" correspond to the upper side and the lower side in the vertical direction.

FIG. 1 is a side view showing the basic configuration of the grinding device 1. FIG. 2 is a plan view of the grinding device 1. FIG. 3 is a partial cross-sectional view taken along the line II of FIG. 2, showing the internal structure of the tilting means 6 and the holding means 3.

The grinding device 1 grinds the back surface of the wafer W by the grinding means 2 to form a thin film. The grinding means 2 includes a grindstone 21, a spindle 22 having the grindstone 21 attached to the tip thereof, and a spindle feed mechanism 23 for feeding the spindle 22 in the vertical direction V.

The grindstone 21 is horizontally attached to the tip of the spindle 22. The wafer W is ground by pressing the grindstone 21 against the wafer W. Hereinafter, the arc-shaped range in which the grindstone 21 grinds the wafer W is referred to as “grinding area A1”.

The spindle 22 rotates the grindstone 21 along the rotation direction C1 about the rotation axis a1 by a motor (not shown).

The spindle feed mechanism 23 includes two linear guides 23 a that connect the column 4 and the spindle 22 and a known ball screw slider mechanism (not shown) that moves the spindle 22 up and down in the vertical direction V. Hereinafter, the feed direction in which the linear guide 23a moves up and down the spindle 22 is referred to as "roll axis Z". In the grinding means 2, a pitch axis direction X1 connecting the linear guides 23a arranged in parallel with the roll axis Z and a yaw axis Y1 perpendicular to the roll axis Z and passing through the rotation center O1 of the grindstone 21 are set. There is.

A wafer chuck 3 as a holding unit is arranged below the grinding unit 2. In addition, the grinding apparatus 1 includes a plurality of wafer chucks 3 in order to continuously grind a plurality of wafers W. The plurality of wafer chucks 3 are arranged around the rotation axis of the index table 5 at predetermined intervals on the circumference.

The wafer chuck 3 includes a chuck 31 and an air bearing 32.

On the upper surface of the chuck 31, an adsorbent (not shown) made of a porous material such as alumina is embedded. The wafer chuck 3 includes a conduit (not shown) that extends through the chuck 31 and the air bearing 32 to the surface of the chuck 31. The pipe is connected to a vacuum source, a compressed air source, and a water supply source (not shown) through a rotary joint (not shown) connected to the rotor 32a of the air bearing 32. When the vacuum source is activated, the wafer W placed on the chuck 31 is sucked and held by the chuck 31. Further, when the compressed air source or the water supply source is activated, the suction between the wafer W and the chuck 31 is released.

The air bearing 32 includes a rotor 32a rotatable around the rotation axis a2, and a stator 32b arranged on the outer periphery of the rotor 32a. The rotor 32a and the chuck 31 are fixed by a bolt (not shown). The rotor 32a is connected to a rotary joint and rotates the chuck 31 about the rotation axis a2 along the rotation direction C2. A predetermined gap (air gap) is provided between the rotor 32a and the stator 32b, and by supplying compressed air from the outside to this gap, the rotor 32a rotates without contact with the stator 32b. be able to. The wafer chuck 3 is set with a yaw axis Y2 that is perpendicular to the roll axis Z and passes through the rotation center O2 of the wafer chuck 3. The yaw axis Y2 of the wafer chuck 3 is parallel to the yaw axis Y1 of the grinding means 2.

The grinding apparatus 1 includes a tilting unit 6 that tilts the rotation axis a2 of the wafer chuck 3 with respect to the rotation axis a1 of the grindstone 21. The tilting means 6 includes a tilt table 61, a fixed support portion 62, an upstream movable support portion 63, and a downstream movable support portion 64.

The tilt table 61 is formed in a substantially triangular shape in a plan view. On the tilt table 61, a fixed support portion 62, an upstream side movable support portion 63, and a downstream side movable support portion 64 are arranged 120 degrees apart on the circumference around the rotation axis a2.

The fixed support portion 62 is fastened to the tilt table 61 with a bolt 62a.

The upstream movable support portion 63 is arranged upstream of the fixed support portion 62 in the rotation direction C2 of the wafer chuck 3. Since the structure of the upstream movable support portion 63 is similar to that of the downstream movable support portion 64, the structure thereof will be described by taking the downstream movable support portion 64 as an example, and the description of the upstream movable support portion 63 will be omitted. .. Note that the number of movable support portions used in the grinding device 1 that can move up and down in the vertical direction V is not limited to two, and may be three or more.

The downstream movable support portion 64 is arranged downstream of the fixed support portion 62 in the rotation direction C2 of the wafer chuck 3. The downstream movable support portion 64 is a nut 64a embedded in the tilt table 61, a tilt ball screw 64b fixed to the index table 5 and having an upper portion screwed into the nut 64a, and a tilt motor for rotating the tilt ball screw 64b. 64c. The downstream movable support portion 64 is formed longer than the fixed support portion 62 in the vertical direction V.

The grinding apparatus 1 includes a scale 7 that measures the amount of sinking of the tilt table 61 due to the load applied when the grinding unit 2 presses the wafer W.

The operation of the grinding device 1 is controlled by the control device 8. The control device 8 controls each of the constituent elements of the grinding device 1. The control device 8 is composed of, for example, a CPU and a memory. The function of the control device 8 may be realized by controlling using software, or may be realized by operating using hardware.

Based on the thickness of the wafer W measured by a thickness sensor (not shown), the controller 8 tilts the rotation axis a2 with respect to the rotation axis a1 so that the grindstone 21 holds the wafer W. Adjust the processing range for grinding. The thickness sensor is not limited to the one included in the configuration of the grinding device 1, and may be, for example, one that feeds back data measured by an external device of the grinding device 1 to the control device 8. Hereinafter, the angle of the rotation axis a2 with respect to the rotation axis a1 is referred to as “tilt angle”. The upstream movable support portion 63 and the downstream movable support portion 64 independently expand and contract along the vertical direction V, and the tilt table 61 inclines with the fixed support portion 62 as a reference, thereby inclining the rotation axis a2. You can

The controller 8 stores data on the grinding amount of the wafer W according to the tilt angle. Thus, the thickness of the wafer W before grinding or the thickness of the wafer W during grinding is measured, and the grinding amount and the tilt angle are adjusted from the difference between this thickness and the desired thickness of the wafer.

Next, the operation of the grinding device 1 will be described with reference to the drawings. FIG. 4 is a plan view showing the positional relationship between the grinding means 2 and the wafer chuck 3. 5A and 5B are schematic diagrams showing how the holding means 3 is tilted according to the axis tilt of the grinding means 1. FIG. 5A shows the state before the axis tilt, and FIG. 5B shows the state after the axis tilt. ..

The grinding means 2 is cantilevered by the column 4 via two linear guides 23a arranged in parallel in the pitch axis X1 direction. Therefore, the grinding means 2 tends to be strong in the yawing component of the back force acting on the grindstone 21 during the grinding process, that is, the rotation around the yaw axis Y1, while being weak in the pitching component, that is, the rotation around the pitch axis X1. is there.

Therefore, in the grinding device 1, the grinding region A1 is arranged so as to straddle the tip of the yaw axis Y1. Compared with the pitching component of the grinding area A2 of the conventional grinding apparatus shown in FIG. 6, the pitching component of the grinding area A1 is set smaller, and the rotational moment about the pitch axis X1 is reduced. The grinding area A1 may be arranged so as to straddle the base end side of the yaw axis Y1. By arranging in this way, the rotational moment about the pitch axis X1 is further reduced and the wafer chuck 3 is also provided. Is arranged below the grinding means 2, the grinding device 1 can be arranged in a space-saving manner.

Further, the grinding means 2 and the wafer chuck 3 are arranged so that the yaw axis Y1 of the grinding means 2 and the yaw axis Y2 of the wafer chuck 3 are separated by ¼ of the diameter of the wafer chuck 3. Therefore, the grinding area A1 is formed symmetrically across the yaw axis Y1, and the pitching component of the grinding area A1 is reduced to the necessary minimum.

The grinding area A1 is preferably formed from the center of the wafer W toward the outer periphery of the wafer W. This suppresses edge chipping when the peripheral edge of the wafer W and the grindstone 21 are in contact with each other.

The tilting means 6 tilts the wafer chuck 3 so that the grindstone 21 and the wafer W are parallel in consideration of the axial tilt of the grinding means 2 caused by the rotation moment around the linear guide 23a due to the weight of the grinding means 2. Is preferred. That is, the grinding means 2 cantilevered by the column 4 may tilt due to its own weight. If the grinding process is performed with the grinding means 2 tilted in this way, the grindstone 21 may hit the wafer W one-sided. .. Therefore, the tilt table 61 is tilted by the same angle as the tilt angle of the grinding means 2.

For example, as shown in FIG. 6A, when the grinding means 2 maintains the horizontal posture, the tilting means 6 adjusts the tilt of the tilt table 61 based on the thickness of the wafer W.

However, as shown in FIG. 6B, when the grinding means 2 tilts due to its own weight, the upstream side movable support portion 63 is extended and the tilt table 61 is tilted in the same manner as the grinding means 2 to perform grinding. It is possible to suppress partial contact between the grindstone 21 and the wafer W due to the axis tilt of the means 2.

In this way, in the grinding apparatus 1 described above, the grinding area A1 is formed so as to straddle the yaw axis Y1, so that the pitching component of the grinding area A1 that induces the rotation of the grinding means 2 about the pitch axis X1 is reduced. Since the rotation of the grinding means 2 around the pitch axis X1 is suppressed, the posture of the grinding means 2 is maintained parallel to the wafer W, and the wafer W can be uniformly ground in the grinding area A1.

Although the grinding apparatus 1 described above has been described by taking the one including the tilting means 6 as an example, it goes without saying that the present invention is also applicable to a grinding apparatus that does not include the tilting means.

The present invention can be variously modified without departing from the spirit of the present invention, and it goes without saying that the present invention extends to the modified ones.

1... Grinding device 2... Grinding means 21... Grinding stone 22... Spindle 23... Spindle feeding mechanism 23a... Linear guide 3... Wafer chuck (holding means)
31... Chuck 32... Air bearing 32a... Rotor 32b... Stator 4... Column 5... Index table 6... Inclination means 61... Tilt table 62... Fixed support Part 62a... Bolt 63... Upstream movable support 64... Downstream movable support 64a... Nut 64b... Tilt ball screw 64c... Tilt motor 7... Scale 8... ..Control device A1... Grinding area W... Wafer

Claims (4)

A holding means for holding and rotating a wafer, a grinding means for grinding the wafer, a cantilevered support for the grinding means, and a central axis for rotating the grinding means parallel to the vertical direction. A feed device for feeding the wafer toward the wafer along a roll axis, comprising:
Ground region in which the grinding means for grinding the wafer, across the yaw axis is passing Ri said grinding means rotatable around axis center of rotation of the grinding wheel of the grinding means in perpendicular to the roll axis in a plan view in is formed in a circular arc shape,
A tilting means for tilting the holding means in accordance with a tilt about a pitch axis which is a central axis through which the grinding means can rotate and which is perpendicular to the roll axis and the yaw axis,
The tilting means is a fixed support portion arranged on a straight line that passes through the rotation center of the holding means when viewed in a plane and is substantially parallel to the pitch axis and on the opposite side of the rotation center of the holding means across the yaw axis. grinding apparatus characterized by comprising a. 2. The grinding apparatus according to claim 1, wherein the grinding area is arranged on the opposite side of the feed means with the center of rotation of the grindstone being sandwiched between the grinding areas. The grinding device according to claim 1, wherein the grinding region is formed symmetrically with respect to the yaw axis in a plan view. 4. The grinding apparatus according to claim 1, wherein the grinding region is formed in an arc shape from the center of the wafer toward the outer circumference of the wafer in a plan view.