JP4892201B2 - Method and apparatus for processing step of outer peripheral edge of bonded workpiece - Google Patents

Description

The present invention relates to a step processing method and apparatus for an outer peripheral edge portion of a bonding work for a high voltage IC in which a semiconductor wafer such as a silicon wafer is electrically insulated and separated by a silicon oxide film or the like and bonded together. by grinding in the radial direction essentially allowed laminating work especially in the right angles to the plane of rotation of the lamination was grindstone plane of the rotation of the workpiece, the machining position of the lamination by grinding work is constantly changing (traversing) so In addition to making it easier for chips to escape to the outside of the bonded workpiece, the grinding resistance is reduced to prevent streaks and cracks caused by damage to the ground surface due to chips, and grinding with a grindstone is shaved downward (of the bonded workpiece) The cutting method in which the grindstone moves downward in the normal direction from the center of the upper one surface and the grinding part moves toward the outer periphery is referred to as “downward cutting” in this specification. By making the bonding work difficult to peel off by applying a force to hold down the bonded workpiece during processing, as a comprehensive effect of these, the remaining amount of the step after processing, which was conventionally limited to 100 μm, The half of the thickness can be reduced to 50 μm, and the etching process time for processing the stepped portion after processing is further reduced to ½ that of the conventional work. The present invention relates to a step processing method and apparatus for an outer peripheral edge part of an epoch-making bonded workpiece capable of dramatically increasing the production efficiency of the SOI substrate and, in turn, the SOI substrate.

At present, as shown in FIGS. 1 to 4, the substrate (bonding work 2 of the present application) of the silicon wafer 1 (1 </ b> A, 1 </ b> B) is electrically connected to at least two silicon wafers 1 </ b> A, 1 </ b> B by the silicon oxide film 3. A substrate for a high voltage IC that has been separated and bonded in isolation, that is, a bonded work 2 called an SOI substrate, is the mainstream. In this bonded work 2, silicon, which is an example of the upper one work piece, is used. Only the wafer 1A is finally processed into a thin film to about 1 μm. Prior to this thin film processing, it is essential that the outer peripheral edge 1a be stepped into a ring shape over a width of several millimeters to make it as thin as possible. It has become.
That is, as shown in FIG. 5, the outermost edge portion 1a of the uppermost portion of the bonded workpiece 2, that is, only the upper one silicon wafer 1A is stepped into a ring shape having a width of several millimeters, and this outer peripheral edge portion 1a is further processed. Etching is performed to reduce the thickness to about 1 μm, and then the other portion (center portion) is ground and only the upper one silicon wafer 1A is finally thinned to about 1 μm to form an SOI substrate. Complete.

18 to 22, the step processing method and apparatus for the peripheral edge portion of the conventional bonded workpiece 2 will be described. As shown in FIG. 20, the bonded workpiece 2 is fixed to a workpiece mounting table 4 such as a suction table. The wheel 5 is rotated at a low speed in the direction of arrow A, and a grindstone 5 such as a cup grindstone containing diamond abrasive grains (see Patent Document 1) is parallel to the rotation surface of the bonded workpiece 2 by a grindstone driving device (not shown) in the direction of arrow B. Is rotated at a high speed and brought into contact with the outer peripheral edge portion 1a of the silicon wafer 1A on the upper side of the bonded work 2, and either the grindstone 5 or the bonded work 2 is moved to a grindstone driving device or a work mounting table driving device (not shown). The outer edge 1a is ground by increasing the depth of cut by the grindstone 5 and the step processing is performed so that only the outer edge 1a becomes thinner in a ring shape than the other parts.

However, in this method, since the rotating surface 5a of the grindstone 5 is parallel to the rotating surface 2a of the laminating workpiece 2, as shown in FIG. 2 rotates in the direction of the arrow A, and the grindstone 5 rotates in the direction of the arrow B. Therefore, both movements are reversed, and the chips 6 produced by grinding between the grindstone 5 and the bonded workpiece 2 are: As shown by the arrow A, the friction with the bonded work 2 is pushed and moved from the upper side to the lower side in the figure, but the upward friction force by the grindstone 5 tries to push it up as shown by the arrow B. . As a result, the chip 6 cannot move in any direction in the vertical direction and is confined in this portion, so that a considerable amount always remains on the outer peripheral edge portion 1a that is being ground, that is, the grinding surface 8. The outer peripheral edge 1a of the bonded workpiece 2 that has been completed has a disadvantage that a very undesirable mark 1b and crack 1c are generated, and chipping and chipping are unavoidable.
This also means that the grinding surface 8 between the grinding stone 5 being ground and the outer peripheral edge 1a of the bonded workpiece 2 is the same even when the rotational direction of the grinding stone 5 is reversed (counterclockwise in FIG. 21). Since it is quite wide, the point that a considerable amount of chips 6 are always confined in the ground surface 8 is the same, so there is no great difference.

In this conventional method, the rotating surface 2a of the bonded workpiece 2 and the rotating surface 5a of the grindstone 5 are parallel to each other, and the bonded workpiece 2 is basically ground in the circumferential direction. Since the torque for preventing the rotation of the silicon wafer 1A only works from the grindstone 5, the force for the silicon wafer 1A to peel from the silicon wafer 1B as an example of the lower workpiece always works. For this reason, there existed a fault that peeling in the outer periphery edge part 1a of the silicon wafer 1A was easy to generate | occur | produce.

As a result, in the conventional step processing method and apparatus described above, the step remaining amount t of the outer peripheral edge portion 1a after processing is limited to 100 μm and cannot be further reduced. For this reason, after this step processing, this portion is thinned to about 1 μm by etching, but it takes a very long time, and the defect rate due to chips and chips is high, so the production efficiency of the SOI substrate is high. This is very bad, and this has become a bottleneck in the production of SOI substrates that have become mainstream.

Various methods and apparatuses for grinding the outer peripheral edge of a workpiece such as a grindstone and a normal silicon wafer have been proposed in Patent Document 1 and other applications of the present applicant. Since the target workpiece is completely different, it is a different invention, and Patent Document 1 is disclosed as a known patent document for reference.
JP 2004-136416 A

The present invention has been made in order to eliminate the above-described drawbacks of the prior art, and the object of the present invention is to bond at least two sheets, and to perform electrical insulation separation with a semiconductor oxide film or the like on the bonding surface. A workpiece mounting base configured to allow chucking of a bonded workpiece in a step machining apparatus for a peripheral edge portion of a workpiece for performing a step machining to reduce only the thickness of the outer peripheral edge portion of the uppermost one of the bonded workpieces When, the the workpiece mount of the drive unit, and a grinding wheel rotating surface is ground to at right angles to the plane of the rotation of the該貼combined work, and a drive device of the whetstone, the workpiece mount the workpiece and While rotating at a low speed by the driving device, the grindstone is brought into contact with the laminating work while being rotated at a high speed by the grindstone driving device, and either the grindstone or the laminating work is brought close to the incision by the grindstone. , And gradually grind the outer peripheral edge of the uppermost workpiece of the bonded workpiece by bringing the grinding stone into contact with the grinding stone downward in the normal direction from the surface side of the bonded workpiece. The two workpieces are sandwiched between the grindstone and the workpiece mounting base while the other workpiece on the opposite side of the surface is chucked, and stepped in an arc shape according to the outer peripheral shape of the grindstone. By this, the grinding surface always changes (traverses), so that chips generated on the grinding surface between the grindstone and the workpiece are not confined to the grinding surface, but always smoothly escape in the radial direction. As a result, no streak, cracks, chips or chips resulting from them are generated at the outer peripheral edge after grinding, and a very clean ground surface can be obtained. It is possible to make the remaining amount of the step at the outer peripheral edge part of the bonded work, which is limited to 100 μm, to half of 50 μm at a stroke, and this makes it possible to perform etching processing which is subsequent thin film processing of the SOI substrate. It is possible to reduce the time required to ½ of the conventional time, and to dramatically improve the quality, yield and production efficiency of the SOI substrate.

Another object of the present invention, in addition to the above structure, lamination angle within 45 degrees from the radial direction of the rotating surface該貼combined and the rotating surface as the plane of rotation at right angles to the grinding wheel with respect to the workpiece of the workpiece The grindstone arranged in an inclined manner is brought into contact with the laminating work while being constrained and rotated, and either the grindstone or the laminating work is brought close to gradually increase the incision by the grindstone. By grinding the outer peripheral edge portion of one upper workpiece by grinding in a direction inclined at an angle of 45 degrees or less from the radial direction, grinding in the direction with the best chip escape efficiency on the grinding surface is possible. In addition, this improves the chip removal efficiency by grinding, obtains a smoother ground surface, prevents streaking and cracks as much as possible, and achieves a step difference of 50 μm at the outer peripheral edge of the bonded workpiece. It is.

Another object of the present invention, in addition to the configuration of the paragraphs 0008, one of the surface center of the combined work bonded grinding by and whetstone as the plane of rotation of the grinding wheel with respect to the plane of rotation of the lamination work at right angles to While rotating at a high speed in a direction in which the grindstone contacts downward from the outer circumference, the grindstone or the laminating work is brought close to contact with the laminating work to gradually increase the incision by the grindstone. Grind the outer peripheral edge of the uppermost workpiece of the laminating workpiece by bringing the grindstone into a normal line direction from the surface side of the laminating workpiece in the normal direction. The two workpieces are sandwiched between the grindstone and the workpiece mounting base while one workpiece is chucked, and the workpiece is bonded from the grindstone during grinding by processing a step in an arc according to the outer peripheral shape of the grindstone. In In this way, the downward pressing force is applied, and the upper workpiece to be ground is prevented from peeling off from the lower workpiece, thereby reducing the defect rate of the SOI substrate and improving the product yield. It is.

Another object of the present invention, in addition to the configuration of the paragraph 0008, and a plurality of grindstone for grinding to the plane of rotation at right angles to the plane of the rotation of the lamination work, the plurality of driving the grindstone of the plurality of simultaneously A grindstone drive device, and a plurality of grindstones are brought into contact with the pasted work while being rotated at a high speed by a plurality of grindstone drive devices while the work piece is rotated at a low speed by the work mount and the drive device for the work mount. Either the grindstone or the bonded workpiece is approached to gradually increase the incision by the grindstone, and the outer peripheral edge of the uppermost workpiece of the bonded workpiece is treated from the surface side of the bonded workpiece. contacting the grindstone down ground line direction, sandwiching two of said workpiece while chucking the other one of the workpiece opposite to the contact surface of the whetstone in the work mount and said grinding wheel, By configured to simultaneously step processing a plurality of locations in an arc shape to match the outer peripheral shape of the serial grindstone, lamination work, combined work one bonded only rotates for example 1 / 2,1 / 3 or 1/4 This is to complete the step processing of the outer peripheral edge portion, and to reduce the processing time per piece in inverse proportion to the number of grindstones, and to improve the production efficiency of SOI substrate compared to the conventional example It is to greatly improve.

Another object of the present invention, in addition to the configuration of the paragraphs 0009, within 45 degrees rotation surface and the rotating surface as the plane of rotation at right angles to the grinding wheel with respect to the lamination workpiece from the radial該貼combined work A plurality of grindstones that are disposed at an angle of the same angle and can be ground at the same time are simultaneously rotated at a high speed to bring the grindstone or the laminating work close to each other to bring the grindstone close to the grindstone. Bonding is performed by gradually increasing the depth of incision and grinding the outer peripheral edge of one workpiece at the top of the bonded workpieces at multiple points by grinding in a direction inclined at an angle of 45 degrees or less from the radial direction. While greatly improving the efficiency of step machining on the outer peripheral edge of the workpiece, it is also the most efficient chip discharge during grinding on the grinding surface, and this also makes the grinding surface extremely Reina addition allows very small step leaving amount as compared with the conventional example, it is possible to improve the quality and production efficiency of the SOI substrate.

In short, the method of the present invention (Claim 1) is a method in which at least two sheets are bonded together, and the thickness of one outer peripheral edge portion of the uppermost part of the bonded work in which the insulating surface is electrically insulated and separated by a semiconductor oxide film or the like on the bonded surface. In the step processing method of the outer peripheral edge portion of the bonded workpiece that performs the step processing to make only the thinning, while attaching the bonded workpiece to a workpiece mounting base configured to be chucked, the bonded workpiece is rotated at a low speed, lamination plane of rotation of the grinding wheel with respect to the plane of rotation of the workpiece is brought close to either the whetstone or該貼combined workpiece in contact with該貼combined workpiece while high speed rotation of the grinding wheel so that at right angles whetstone The incision by is gradually increased, and the outer peripheral edge of the uppermost workpiece of the bonded workpiece is brought into contact with the grindstone in the normal direction from the surface side of the bonded workpiece. Cutting to the other one of the workpiece opposite to the contact surface of the whetstone sandwiched two of said workpiece while chucked the work mount and said grinding wheel, arcuately to match the peripheral shape of the grinding wheel It is characterized by step processing.

Further, the method of the present invention (Claim 2) is that the thickness of one outer peripheral edge portion of the uppermost part of the bonded workpiece in which at least two sheets are bonded and the bonded surface is electrically insulated and separated by a semiconductor oxide film or the like. In the step processing method of the outer peripheral edge portion of the bonded workpiece that performs the step processing to make only the thinning, while attaching the bonded workpiece to a workpiece mounting base configured to be chucked, the bonded workpiece is rotated at a low speed, laminating fast from one surface center of combined work bonded grinding the rotational surface of the grinding wheel with respect to the plane of rotation by way and whetstone at right angles to the workpiece in a direction whetstone in the outer peripheral direction is in contact with the downward The laminating workpiece is brought into contact with the laminating workpiece while rotating to bring either the grindstone or the laminating workpiece closer to gradually increase the incision by the grindstone. The outer peripheral edge of the workpiece is ground by bringing the grindstone into contact in the normal direction from the surface side of one of the bonded workpieces, and the other workpiece on the side opposite to the contact surface of the grindstone is chucked. The two workpieces are sandwiched between the grindstone and the workpiece mounting base while being king, and stepped in a circular arc shape according to the outer peripheral shape of the grindstone .

The apparatus of the present invention (Claim 3) has a thickness of one outer peripheral edge part of the uppermost part of a bonded work in which at least two sheets are bonded and the insulating surface is electrically insulated and separated by a semiconductor oxide film or the like. In the step processing apparatus for the outer peripheral edge portion of the bonded workpiece that performs the step processing to make the thickness of the workpiece thinner, the workpiece mounting base configured to be able to chuck the bonded workpiece, the drive device for the workpiece mounting base, and the bonding a grindstone for grinding to the plane of rotation at right angles to the plane of the rotation of the workpiece, and a drive device for whetstone, rotating at low speed the lamination workpiece by said workpiece mounting table and the workpiece mount the drive unit However, the grindstone is rotated at a high speed by the grindstone driving device and brought into contact with the laminating work to bring either the grindstone or the laminating work close to each other, and the incision by the grindstone is gradually increased. And grinding the outer peripheral edge of the uppermost workpiece of the bonded workpiece by bringing the grinding stone into contact in the normal direction from the surface side of the one workpiece of the bonded workpiece, While the other workpiece on the opposite side of the surface is chucked, the two workpieces are sandwiched between the grindstone and the workpiece mounting base and stepped in an arc shape in accordance with the outer peripheral shape of the grindstone . It is characterized by this.

In the present invention, as described above, at least two sheets are bonded together, and only the thickness of the outer peripheral edge part of the uppermost part of the bonded work that is electrically insulated and separated by a semiconductor oxide film or the like on the bonded surface is obtained. In the step processing device at the outer peripheral edge portion of the workpiece for performing the step processing to be thinned, the workpiece mounting base configured to be able to chuck the bonded workpiece, the drive device for the workpiece mounting base, and the rotating surface of the bonded workpiece a grindstone for grinding so that the rotation plane is at right angles against, and a driving device for whetstone, while the low-speed rotation of the workpiece by the workpiece mount and a driving device, while a high speed by a grinding wheel driving device grindstone The outer peripheral edge of one workpiece at the top of the bonded workpiece is made to contact with the bonded workpiece to increase either the grindstone or the bonded workpiece and gradually increase the incision by the grindstone. It was ground in contact with the downward grindstone in the direction normal to the one surface side of the lamination work, two of the workpiece while chucking the other one of the workpiece opposite to the contact surface of the whetstone Since it is sandwiched between the grindstone and the work mounting base and processed to be stepped in an arc shape according to the outer peripheral shape of the grindstone , the grinding surface always changes (traverses). Chips generated on the grinding surface between them are not confined to the grinding surface, and can always escape smoothly in the radial direction.As a result, streaks and cracks are formed on the outer peripheral edge after grinding. In addition, there is no chip or chipping caused by these, and a very clean ground surface can be obtained. At the same time, the amount of remaining step at the outer peripheral edge of the bonded workpiece, which has been limited to 100 μm in the past, can be obtained. There is an effect that can be reduced to 50 μm, which is 1/2 of that, and as a result, the time required for the etching process, which is a subsequent thin film processing of the SOI substrate, can be shortened to 1/2 of the conventional substrate. There is an effect that the quality, the yield and the production efficiency can be dramatically improved.

In addition to the above-described configuration, lamination work angle inclined allowed by arrangement of the plane of rotation of the grinding wheel with respect to the plane of rotation within 45 degrees and the rotating surface as at right angles to the radial該貼combined work The grindstone is brought into contact with the laminating work while rotating at a high speed to bring either the grindstone or the laminating work closer to gradually increase the incision by the grindstone, and the uppermost one of the laminating works since the outer peripheral edge portion of the workpiece so as to step processing by the angle direction inclined by grinding within 45 degrees from the radial direction, allows the best direction of the grinding efficiency of the escape of the chip in the ground surface, and this results The chip discharge efficiency by grinding can be increased, a smoother grinding surface can be obtained, the generation of streaks and cracks can be prevented as much as possible, and the step remaining amount of the outer peripheral edge of the bonded workpiece can be 50 μm. There is an effect that can be bet.

Further in addition to the preceding paragraph 0020, the in the outer peripheral direction from one surface center of combined work bonded grinding by and whetstone as the plane of rotation of the grinding wheel with respect to the plane of rotation of the lamination work at right angles to While rotating at a high speed in a direction in which the grindstone contacts downward, the grindstone or the laminating work is brought close to each other by bringing it into contact with the laminating work to gradually increase the incision by the grindstone. Grinding the outer peripheral edge of one workpiece by bringing the grinding stone into contact with the grinding stone in the normal direction from the surface side of one of the bonded workpieces, and chucking the other workpiece on the opposite side of the contact surface of the grinding stone Since the two workpieces are sandwiched between the grindstone and the workpiece mounting base while being king, and stepped in an arc shape in accordance with the outer peripheral shape of the grindstone, the grinding stone faces downward from the grindstone during grinding. of A holding force can be applied, and as a result, the upper workpiece to be ground can be prevented from peeling from the lower workpiece, the defect rate of the SOI substrate can be reduced, and the product yield can be improved. There is an effect that can be done.

Further in addition to the preceding paragraph 0020, it includes a plurality of grinding wheel for grinding to the plane of rotation at right angles to the plane of the rotation of the lamination work, and a plurality of driving device for driving a grinding wheel of the plurality of simultaneously , While rotating the bonded workpiece at a low speed by the workpiece mounting table and the drive device of the workpiece mounting table, the plurality of grinding stones are brought into contact with the bonded workpiece while being rotated at a high speed by the driving device of the plurality of grinding stones. The cutting edge by the grindstone is gradually increased by approaching either of them, and the outer peripheral edge of the uppermost workpiece of the bonded workpiece is moved downward in the normal direction from the front surface side of the bonded workpiece. the contacted by grinding, sandwiched two of said workpiece while chucking the other one of the workpiece opposite to the contact surface of the whetstone in the work mount and the grinding wheel, the outer peripheral shape of the grinding wheel Since it is configured to simultaneously step processing a plurality of locations in an arc shape to fit, the step processing of just lamination work one circumferential edge lamination workpiece is rotated, for example, 1 / 2,1 / 3 or 1/4 As a result, the processing time per sheet is reduced in inverse proportion to the number of grindstones, and the production efficiency of the SOI substrate can be greatly improved as compared with the conventional example. effective.

Further in addition to the preceding paragraph 0021, with and rotating surface該貼combined by an angle inclined within 45 degrees from the radial direction of the workpiece to such plane of rotation of the grinding wheel with respect to the plane of rotation of the lamination work at right angles to A plurality of grindstones that can be arranged and subjected to the same grinding process are simultaneously rotated at a high speed to bring the laminating workpiece into contact with the laminating workpiece and bring either the grindstone or the laminating workpiece close to each other, and the incision by the grindstone is gradually increased. Since the outer peripheral edge of the uppermost workpiece of the bonded workpiece is processed in steps at a plurality of locations by grinding in a direction inclined at an angle within 45 degrees from the radial direction, While greatly improving the efficiency of step processing at the outer peripheral edge, it is possible to most efficiently discharge chips during grinding on the grinding surface, and as a result, the grinding surface may be very clean. Enables the amount leaving very small level difference compared to come example, the effect can be achieved significant improvement in quality and production efficiency of the SOI substrate can be obtained.

  Hereinafter, the present invention will be described based on embodiments shown in the drawings. In FIG. 6, at least two step processing devices 10 at the outer peripheral edge portion of the bonded workpiece according to the present invention are bonded, and the insulating surface is electrically insulated and separated by the silicon oxide film 3 as an example of the semiconductor oxide film on the bonded surface. 1 is a step processing device for an outer peripheral edge portion of a workpiece that performs a step processing to reduce only the thickness of the outer peripheral edge portion 1a of the uppermost one (silicon wafer 1A) of the bonded workpiece 2 that is bonded. A workpiece mounting base drive device (not shown), a grindstone 15, and a grindstone drive device 11. In addition, since it was already demonstrated in detail in the column of background art about the bonding work 2, the description is abbreviate | omitted here.

The workpiece mounting base 4 is configured so that the bonded workpiece 2 can be chucked. Usually, a known suction table as shown in the drawing that sucks the bonded workpiece 2 by vacuum is used. The apparatus is not limited to the suction table, and may be a device that frictionally drives the outer periphery of the bonded workpiece 2 with a plurality of rollers or the like.
Further, in the illustrated embodiment, the work mounting base 4 is a horizontal type of horizontal arrangement, but is not limited thereto, and may be a vertical type such as a vertical arrangement.

A workpiece mounting table drive device (not shown) uses a known servo mechanism, and numerically controls the workpiece mounting table 4 as shown by an arrow A to rotate it in one direction at a low speed. In order to approach or leave the grindstone 15, it is configured to move horizontally in the directions of arrows C and D (Y-axis direction control) and to move up and down in the directions of arrows E and F (Z-axis direction control). ing.

Grinding wheel 15, so that the rotation plane 15a is at right angles to the plane of the rotation 2a of the lamination work 2, substantially parallel to the rotational surface 2a of the combined workpiece 2 or spindle 22 which is a rotation axis of the grinding wheel 15 is bonded It is arranged in the direction of arrow G by a spindle 22 that is rotationally driven by a belt 21 wound around a pulley 20 fixed to a rotating shaft (not shown) of a motor 19 attached to a movable base 18. That is, it is configured to rotate at a high speed so as to cut downward on the bonded workpiece 2, and is fixed to the spindle 22 by an appropriate means so as to be replaceable. The grindstone 15 includes diamond abrasive grains, and a metal bond grindstone that is normally used for rough grinding is used. A chamfer (1R) with a radius of about 1 mm is applied to the outer peripheral corner portion 15b.
In addition, in the Example shown in FIG.6 and FIG.7, although the grindstone 15 is arrange | positioned toward the perfect radial direction of the bonding workpiece | work 2, this is not limited to this direction, FIG. It may be arranged to be inclined with respect to the radial direction in the range of 45 degrees so that the movement of the grindstone 15 on the cutting surface 8 is not opposite to the rotation direction of the bonded workpiece 2 from the position of (See FIG. 12).
The range of the inclination angle is limited to 45 degrees. If the inclination angle is increased too much beyond 45 degrees, the length of the grinding surface 8 becomes longer, and the time for the chips 6 to stay in the grinding surface 8 becomes longer accordingly. As a result, the discharge efficiency of the chips 6 is lowered.
If the inclination angle is within a range of 45 degrees, the time for the chips 6 to stop on the grinding surface 8 is short, the chip 6 discharge efficiency can be kept high, the peripheral speed of the grindstone 15 and the bonded work 2 The relative grinding direction determined by the relative motion of the grinding surface 8 with respect to the peripheral speed can also be the complete radial direction of the bonded workpiece 2, and the grinding line formed on the grinding surface 8 by grinding (by the grindstone 15). This is because a line assembly formed by cutting can be a complete radial direction of the bonded workpiece 2.
In addition, it is possible to incline this grinding line by 45 degrees with respect to the radial direction of the bonded workpiece 2. From conventional experience, the grinding line is in the same direction or 45 degrees from the radial direction of various workpieces. This is because a grinding method that tilts in a range has obtained very good results.

The grindstone driving device 11 includes, for example, the movable table 18, the motor 19, the pulley 20, the belt 21, the spindle 22, and the like. (Y-axis direction control), and can be moved in the vertical direction (Z-axis direction control) as indicated by arrows K and L.

A cooling water injection nozzle 24 for injecting cooling water (coolant) 23 to the grinding surface 8 between the grindstone 15 and the bonding work 2 is attached above the bonding work 2.

Next, a second embodiment of the present invention shown in FIGS. 11 and 12 will be described. The step work processing apparatus 10 for the bonded workpiece is bonded to at least two sheets, and the uppermost one of the bonded workpieces 2 is electrically bonded with the silicon oxide film 3 as an example of the semiconductor oxide film on the bonded surface. This is a step processing device for a peripheral edge portion of a bonded workpiece that performs a step processing to reduce only the thickness of the outer peripheral edge portion 1a of the (silicon wafer 1A), and is a workpiece mounting configured to allow chucking of the bonded workpiece 2 A rotating surface 15a is provided with respect to the rotating surface 2a of the base 4 (not shown in the second embodiment, see the first embodiment), the drive device (not shown) for the work mounting base, and the bonded work 2 a grinding wheel 15 of a plurality (four in the illustrated embodiment) to be ground so that at right angles, which is an example spindle of a driving device of a plurality of driving the grinding wheel 15 of the plurality of simultaneously (four in the illustrated embodiment) 22 And has While the laminating work 2 is rotated at a low speed by the work mounting base and the drive device for the work mounting base, the grindstone 15 or the laminating work is brought into contact with the laminating work 2 while the plural grindstones 15 are rotated at a high speed by the plural spindles 22. 2 is approached and the incision is gradually increased by the grindstone 15, and the outer peripheral edge portion 1a of the uppermost workpiece (silicon wafer 1A) of the bonded workpiece 2 is basically ground by its radial direction. It is configured to process a step at a plurality of locations simultaneously.

Next, a modification of the second embodiment of FIG. 11 will be described with reference to FIG. 12. The step processing device 10 at the outer peripheral edge portion of the bonded workpiece is a rotating surface 15 a of the grindstone 15 with respect to the rotating surface 2 a of the bonded workpiece 2. grinding wheel 15 of a plurality of (four in the illustrated embodiment) but which may as and rotating surface 15a is an angle inclined within 45 degrees from the radial direction of the combined workpiece 2 bonded to disposed the same grinding at right angles to Are simultaneously rotated at a high speed to bring the grindstone 15 or the laminating work 2 into close contact with the laminating work 2 at a plurality of locations to gradually increase the incision by the grindstone 15, and at the top of the laminating work 2 The outer peripheral edge portion 2a of one workpiece (silicon wafer 1A) is configured to be stepped simultaneously at a plurality of locations by grinding in a direction inclined at an angle of 45 degrees or less from the radial direction.
The inclination of the grindstone 15 within 45 degrees tilts the grindstone 15 within 45 degrees in the clockwise direction from the state of FIG. 11, and not the counterclockwise inclination. This is because the moving direction of the grindstone 15 on the grinding surface 8 does not oppose the moving direction of the bonded workpiece 2.

The method of the present invention (Claim 1) is that at least two sheets are bonded together, and the uppermost sheet (silicon wafer 1A) of the bonded work 2 in which the insulating surface is electrically insulated and separated by a semiconductor oxide film or the like is bonded to the bonded surface. In the step processing method of the peripheral edge portion of the bonded workpiece for performing the step processing to reduce only the plate thickness of the outer peripheral edge portion 1a, the bonded workpiece 2 is attached to the workpiece mounting base 4 configured to be able to chuck the bonded workpiece 2. while low speed attached, whetstone rotating surface 15a of the grinding wheel 15 relative to the rotating surface 2a of該貼combined workpiece 2 is brought into contact with the該貼combined workpiece 2 while the grinding wheel 15 is rotated at high speed so that at right angles 15 or the laminating workpiece 2 is approached to gradually increase the depth of cut by the grindstone 15, and the outer peripheral edge of the uppermost one workpiece (silicon wafer 1 </ b> A) of the laminating workpiece 2. The part 1a is ground by bringing the grindstone 15 into contact with the grindstone 15 downward in the normal direction from one surface side of the bonded workpiece 2, and the other workpiece (silicon wafer 1B) on the opposite side of the contact surface of the grindstone 15 In this method, two workpieces 2 are sandwiched between the grindstone 15 and the work mounting base 4 while being chucked, and stepped in a circular arc shape in accordance with the outer peripheral shape of the grindstone 15 .

In addition, the method of the present invention (Claim 2) is a method of forming the uppermost sheet (silicon wafer 1A) of the bonded workpiece 2 in which at least two sheets are bonded and the bonded surfaces are electrically insulated and separated by a semiconductor oxide film or the like. In the step processing method of the peripheral edge portion of the bonded workpiece for performing the step processing to reduce only the plate thickness of the outer peripheral edge portion 1a, the bonded workpiece 2 is attached to the workpiece mounting base 4 configured to be able to chuck the bonded workpiece 2. While being attached and rotated at a low speed, the rotating surface 15a of the grindstone 15 is substantially perpendicular to the rotating surface 2a of the bonded workpiece 2 and the rotating surface 15a is within 45 degrees from the radial direction of the bonded workpiece 2. While the grindstone 15 disposed at an angle of is rotated at a high speed, the grindstone 15 is brought into contact with the bonded workpiece 2 to bring either the grindstone 15 or the bonded workpiece 2 close to each other, and cutting with the grindstone 15 is performed. Second is increased, there is a method of step processing by the direction of the grinding an outer peripheral edge portion 1a of the angular inclination of within 45 degrees from the radial direction of the top of one of the work of lamination workpiece 2 (silicon wafer 1A).

In addition, the method of the present invention (Claim 2 ) is a method for forming the uppermost sheet (silicon wafer 1A) of the bonded workpiece 2 in which at least two sheets are bonded and the insulating surfaces are electrically insulated and separated on the bonded surfaces. In the step processing method of the peripheral edge portion of the bonded workpiece for performing the step processing to reduce only the plate thickness of the outer peripheral edge portion 1a, the bonded workpiece 2 is attached to the workpiece mounting base 4 configured to be able to chuck the bonded workpiece 2. while low speed attached, from one surface center of combined work 2 bonded grinding by and with the whetstone 15 as rotating surface 15a is at right angles to the grinding wheel 15 relative to the rotating surface 2a of該貼combined work 2 The grindstone 15 is brought into contact with the laminating workpiece 2 while rotating at high speed in a direction in which the grindstone 15 contacts downward in the outer circumferential direction, and either the grindstone 15 or the laminating workpiece 2 is approached to cut by the grindstone 15. The outer peripheral edge portion 1a of the uppermost bonded workpiece (silicon wafer 1A) of the bonded workpiece 2 is moved from the front surface side of the bonded workpiece 2 to the normal direction from the surface of the bonded workpiece 2. Grinding by contacting downward, and sandwiching another workpiece 2 (silicon wafer 1B) opposite to the contact surface of the grindstone 15 between the two workpieces 2 with the grindstone 15 and the workpiece mounting base 4, This is a method of processing a step in an arc shape in accordance with the outer peripheral shape of 15 .

The present invention is configured as described above, and the operation thereof will be described below. First, the outline of the operation of the present invention will be described. As shown in FIG. 1, the silicon wafer 1A is electrically insulated by the silicon oxide film 3 and bonded to the silicon wafer 1B. As shown in FIGS. The bonded work 2 is completed. At this time, as shown in FIGS. 3 and 4, the outer circumferences of the silicon wafer 1 </ b> A and the silicon wafer 1 </ b> B are considerably rounded and have a considerably rounded shape.
When the step processing is completed, as shown in FIG. 5, the bonded workpiece 2 in which only the outer peripheral edge portion 1a of the silicon wafer 1A is thinned in a ring shape is completed. In the present invention, it is possible to reduce the step remaining amount t (see FIG. 16) of the outer peripheral edge portion 1a to 50 μm, which is 1/2 of the conventional one. Note that no processing is performed on the silicon wafer 1B.

Next, the operation of the first embodiment of the present invention will be described in detail with reference to FIGS. 6 to 8 and FIGS. 13 to 17. FIG. In FIG. 6, the bonded workpiece 2 is attracted to the workpiece mounting base 4 by vacuum suction, centered, and fixed. In this state, the grindstone 15 is not yet in contact with the bonded workpiece 2, and the bonded workpiece 2 starts rotating in the direction of arrow A at a low speed (for example, about 1 rpm) together with the workpiece mounting base 4.

Therefore, the motor 19 is rotated, and the spindle 20 is rotated by the pulley 20, whereby the grindstone 15 starts to rotate in the direction of arrow G, that is, grinding with the grindstone 15 is turned downward at a high speed (for example, about 3000 rpm). To do. At this time, the cooling water 23 is injected from the cooling water injection nozzle 24 onto the grinding surface 8 between the grindstone 15 and the bonded workpiece 2.
When the position of the grindstone 15 is fixed, the work mounting base 4 moves in the direction of the arrow C, and as shown in FIG. 6, the outer peripheral edge portion 1a is brought close to the grindstone 15 as shown in FIG. As shown in FIG. 2, the outer edge portion 1a comes into contact with the grindstone 15 and at the same time the step machining is started. Then, as shown in FIG. 8, the cutting of the grindstone 15 is gradually increased, and only the outer peripheral edge portion 1 a of the silicon wafer 1 </ b> A is thinly stepped into an arc shape in accordance with the outer peripheral shape of the grindstone 15. When the operation excluding the rotation of the workpiece mounting base 4 is fixed, the grindstone 15 moves as indicated by an arrow I and descends as indicated by an arrow K so that the grindstone 15 contacts the bonded workpiece 2.

At this time, as shown in FIG. 7, rotating surface 15a of the grinding wheel 15 is arranged at right angles to the rotating surface 2a of the lamination work 2, also rotating surface 15a of the grinding wheel 15 is the radius of the lamination work 2 The outer circumference of the grindstone 16 on the side of the grinding surface 8 is constantly moving at a high speed toward the outside in the radial direction of the bonded workpiece 2, and the grinding surface 8 is rotated by the rotation of the bonded workpiece 2. Changes in time, i.e., traversing, and the discharge of the chips 6 on the grinding surface 8 are performed very smoothly in combination with these actions. This effect is illustrated in detail in FIGS.
Since the chip 6 moves on the grinding surface 8 on the outer periphery of the grindstone 15 always toward the outside of the bonded work 2 in the radial direction, the chip 6 is discharged to the outside very smoothly as indicated by the arrow M, and its discharge efficiency. Is very high and hardly remains on the grinding surface 8.
For this reason, as shown in FIG. 17, the ring-shaped stepped portion of the bonded workpiece 2, that is, the surface of the outer peripheral edge portion 1a of the silicon wafer 1A is finished very finely, and the streaks 1b and cracks found in the conventional example are obtained. 1c does not occur at all, and no chip or chipping occurs.
Moreover, the step remaining amount t shown in FIG. 16 can be reduced to 50 μm, which is halved from 100 μm, which was the conventional limit.

Further, since the grindstone 15 is rotated downward as indicated by an arrow G and the workpiece 2 is cut downward , a force pressing from the grindstone 15 to the outer peripheral edge portion 1a of the silicon wafer 1A is always applied during grinding. Therefore, even if the thickness is reduced by processing, the silicon wafer 1A is difficult to peel off from the silicon wafer 1B, and there is no possibility of peeling.

Next, the operation of the second embodiment of the present invention shown in FIGS. 11 and 12 will be described. First, in the step machining apparatus 10 at the outer peripheral edge portion of the bonded workpiece in FIG. 11, four grindstones 15 are arranged at intervals of 90 degrees, and the rotating surface 15 a of the grindstone 15 is the rotating surface 2 a of the bonded workpiece 2. since respect to are right angles, and substantially aligned in a radial direction of the lamination workpiece 2, although the actions of the individual wheels unchanged from the first embodiment, in this second embodiment, four of the grinding wheel 15 Since the four places of the bonded workpiece 2 can be ground at the same time, the processing is completed when the bonded workpiece 2 is rotated 90 degrees, so the processing time is reduced to ¼ compared to the case of the single grindstone 15. It is shortened and the machining efficiency is quadrupled.

In the step processing apparatus 10 at the outer peripheral edge portion of FIG. 12, the four grindstones 15 are the same as those in FIG. 11, but each grindstone 15 has a rotating surface 15 a having a radius of the bonded workpiece 2. Since it is inclined within the range of 45 degrees from the direction, the grinding line of the outer peripheral edge 1a differs for each inclination angle, and the direction of this grinding line can be freely set within the range of 45 degrees.
That is, it is possible to select an inclination angle with the highest surface cleanness of the step processed portion and the highest chip discharge efficiency, and the best step processing can be performed.

FIGS. 1 to 10 and FIGS. 13 to 17 relate to a first embodiment of the present invention, and FIG. 1 is a perspective view showing two silicon wafers and a silicon oxide film before bonding. It is a perspective view of the bonding workpiece completed by bonding. It is an enlarged front view of a bonding workpiece. It is a partial enlarged front view of the bonding workpiece | work of FIG. It is a perspective view of the bonding workpiece | work which level | step difference processing was completed. It is a perspective view which shows the processing state of the level | step difference processing apparatus of the outer periphery edge part of a bonding workpiece | work. It is a schematic plan view which shows the processing state of the level | step difference processing apparatus of the outer periphery edge part of a bonding workpiece | work. It is a schematic front view which shows the processing state of the level | step difference processing apparatus of the outer periphery edge part of a bonding workpiece | work. It is a side view of a grindstone. It is a front view of a grindstone. FIGS. 11 and 12 relate to a second embodiment of the present invention, and FIG. 11 is a schematic plan view of a step machining apparatus for an outer peripheral edge portion of a bonded workpiece in which the rotation surface of a grindstone is substantially matched with the radial direction of the bonded workpiece. It is. FIG. 11 is a schematic plan view of a step machining apparatus for an outer peripheral edge portion of a bonded workpiece in which the rotating surface of the grindstone is disposed with an inclination of approximately 45 degrees with respect to the radial direction of the bonded workpiece. It is a principal part enlarged side view in the state where level difference processing was started. It is a principal part enlarged side view in the state where level difference processing was almost completed. It is a principal part longitudinal cross-sectional view which shows the discharge state of the chip | tip in a grinding surface. It is a partial expanded longitudinal cross-sectional view which shows the level | step difference remaining amount of the bonding workpiece | work which level | step difference processing was completed. It is a perspective view of the bonding workpiece | work which level | step difference processing was completed. 18 to FIG. 22 relate to a conventional example, and FIG. 18 is a perspective view of a bonded workpiece that has been processed with a step. It is a schematic plan view which shows the processing state of the level | step difference processing apparatus of the outer periphery edge part of the bonding workpiece | work which made the rotation surface of the grindstone parallel to the rotation surface of the bonding workpiece. It is a schematic front view which shows the processing state of the level | step difference processing apparatus of the outer periphery edge part of a bonding workpiece | work. It is a general | schematic fragmentary top view which shows the state in which a chip | tip is confined in the grinding surface. FIG. 3 is a partially enlarged longitudinal sectional view of a bonded workpiece after completion of processing in which streaks and cracks are generated on the ground surface and the residual residue amount is as large as 100 μm.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Silicon wafer 1A One upper silicon wafer 1B One lower silicon wafer 1a Outer edge part 2 Bonding work 2a Rotating surface 3 Silicon oxide film which is an example of semiconductor oxide film 4 Work mounting base 10 Step processing device 11 at outer peripheral edge portion Grinding wheel drive device 15 Grinding wheel 15a Rotating surface

Claims (3)

At least two sheets are bonded together, and the bonded work is processed with a step to reduce only the thickness of the outer peripheral edge of the uppermost sheet of the bonded work that has a semiconductor oxide film or the like on the bonding surface. In the step processing method of the outer peripheral edge part of the grindstone with respect to the rotating surface of the bonded workpiece while attaching the bonded workpiece to the workpiece mounting base configured to be chucked with the bonded workpiece and rotating it at a low speed. the plane of rotation to close either the whetstone or該貼combined workpiece in contact with該貼combined workpiece while high speed rotation of the grinding wheel so that at right angles gradually increase the cut by the abrasive stone, the lamination work The outer peripheral edge part of the uppermost one workpiece is ground by bringing the grinding stone into contact with the grinding stone in the normal direction from the one surface side of the bonded workpiece, and the one on the opposite side to the contact surface of the grinding stone Sandwiching a sheet of the workpiece two of said workpiece while chucked the work mount and the grinding wheel, the outer periphery of the lamination work, characterized in that the step processing in an arc shape to match the outer peripheral shape of the grinding wheel Step processing method for edges. At least two sheets are bonded together, and the bonded work is processed with a step to reduce only the thickness of the outer peripheral edge of the uppermost sheet of the bonded work that has a semiconductor oxide film or the like on the bonding surface. In the step processing method of the outer peripheral edge part of the grindstone with respect to the rotating surface of the bonded workpiece while attaching the bonded workpiece to the workpiece mounting base configured to be chucked with the bonded workpiece and rotating it at a low speed. while the plane of rotation is rotated at a high speed in a direction whetstone from the surface center of one of the work of combined workpiece pasting the grinding and with due whetstone so at right angles to the outer circumference is in contact with the downward contacts the該貼combined work Let either the grindstone or the laminating workpiece approach to gradually increase the incision by the grindstone, the outer peripheral edge portion of the uppermost laminating workpiece of the laminating workpiece, Wherein from one surface side of the serial lamination work the grinding wheel in the normal direction in contact downwardly ground, two while chucking the other one of the workpiece opposite to the contact surface of the whetstone A step machining method for an outer peripheral edge portion of a bonded workpiece, characterized in that the workpiece is sandwiched between the grindstone and the workpiece mounting base and stepped in a circular arc shape in accordance with the outer circumferential shape of the grindstone . At least two sheets are bonded together, and the bonded work is processed with a step to reduce only the thickness of the outer peripheral edge of the uppermost sheet of the bonded work that has a semiconductor oxide film or the like on the bonding surface. In the step processing apparatus of the outer peripheral edge portion of the workpiece, the workpiece mounting base configured to be capable of chucking the bonded workpiece, the drive device of the workpiece mounting platform, and the rotation surface of the workpiece mounting surface are straight. A grindstone that grinds to a corner and a drive device for the grindstone, and the grindstone is rotated by the drive device for the grindstone while rotating the bonded workpiece at a low speed by the work mount and the drive device for the work mount. While rotating at high speed, contact with the laminating workpiece to bring either the grindstone or the laminating workpiece closer to gradually increase the incision by the grindstone, The outer peripheral edge portion of one of the workpieces is ground with the grindstone contacting downwardly from the surface side of one of the bonded workpieces in the normal direction, and another piece on the opposite side of the contact surface of the grindstone is ground. A bonded workpiece characterized in that the workpiece is chucked between the two workpieces with the grindstone and the workpiece mounting base, and is stepped in an arc shape according to the outer peripheral shape of the grindstone . A step processing device for the peripheral edge.

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