JP7419467B2 - Wafer, wafer thinning method, and wafer thinning device - Google Patents

Description

The present invention relates to a method for manufacturing a semiconductor substrate, and more particularly to a wafer, a wafer thinning method, and a wafer thinning apparatus that can improve the yield when thinning a semiconductor wafer.

Semiconductor manufacturing technology consists of machining technology, lithography technology, thin film formation technology, etching technology, ion implantation technology, cleaning technology, etc. Semiconductor machining technology includes cutting (slicing), grinding, lapping, polishing, CMP (chemical mechanical polishing), and back grinding in each process of wafer manufacturing, wafer processing, chipping, and assembly. , dicing, etc.

In addition, demand for applications such as thin cards and wireless tags has recently increased, and demand for high-density packaging has also increased. In order to meet these demands, it is necessary to make wafers extremely thin, and the demand for ultra-thin technology is increasing. In order to make wafers extremely thin, various improvements have been made to devices and methods for wafer grinding. In addition, the diameter of wafers is increasing to improve productivity and reduce costs, but in order to achieve ultra-thin wafers with large diameters, polishing/grinding methods, finishing methods, processing equipment, and transportation methods are required. Many efforts are needed for this purpose.

Semiconductor wafers are thinned by back grinding, which grinds the semiconductor wafer from the back side to the desired thickness.If the semiconductor wafer is simply ground from the back side, the mechanical strength of the semiconductor wafer decreases. It becomes easy to break. Further, the semiconductor wafer becomes easily warped, and as a result, when the layer is thinned, the defective rate of the semiconductor wafer due to cracking or warping increases rapidly.

In order to prevent an increase in the defective rate of semiconductor wafers due to cracks and warping caused by back grinding, the back side of the semiconductor wafer is ground leaving a few mm of the outer edge, and the inside of the outer edge of the semiconductor wafer is thinned. Layer. That is, it is known to form a recess inside the outer edge, and is described in, for example, Patent Document 1.

In addition, an annular step is formed on the periphery of the surface side of the chamfered wafer before thinning to prevent a knife edge. Patent Document 2 describes that the depth is a depth corresponding to the target thickness of the wafer after thinning.

Japanese Patent Application Publication No. 2007-335659 Japanese Patent Application Publication No. 2007-152906

The above-mentioned conventional technology is effective in reducing the risk of transporting thin wafers, reducing warping, and can reduce edge chipping. However, it has been difficult to improve the quality of wafers by mechanically polishing them in order to prevent damage to the wafers due to the micro-crack (fine scratches and fissures) layer caused by back-grinding.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to eliminate damage to the wafer end surface caused by handling operations after wafer shape processing and damage to the wafer end surface during the process of pressing a polishing tape against the edge of the wafer end surface. The aim is to improve productivity and profitability.

The structure of the present invention for achieving the above object is as follows.

[1] A wafer thinning method in which the wafer is processed to a desired thickness by back-grinding, the edge portion of the outer periphery of the wafer being processed as a chamfer, and the top of the chamfer being thinned from the top surface of the wafer. The wafer is horizontally removed from the outer periphery to the inner periphery until the desired thickness (T) is reached, and the removal length from the outer periphery is L, the angle φ of the chamfered part with respect to the horizontal, and the margin α, When processing into a shape where L = T / tan φ + α, the angle φ is determined so that the polishing tape that polishes the outermost peripheral part of the wafer and the corner of the edge part do not come into point contact after the processing. A wafer thinning method characterized by:
[2] A wafer thinning method in which the wafer is processed to a desired thickness by back-grinding, the edge portion of the outer periphery of the wafer being processed as a chamfer, and the top of the chamfer being thinned from the top surface of the wafer. The wafer is horizontally removed from the outer periphery to the inner periphery until the desired thickness (T) is reached, and the removal length from the outer periphery is L, the angle φ of the chamfered part with respect to the horizontal, and the margin α, Wafer thinning characterized in that the wafer is processed into a shape such that L=T/tanφ+α, and the angle φ is determined so that the inner surface of the wafer transport cassette and the corner of the edge portion do not come into point contact. Method.
[3] A wafer thinning device that processes a wafer to a desired thickness by back-grinding, including a chamfering device that processes the edge portion of the wafer outer periphery as a chamfer, and a chamfering device that processes the wafer outer circumference as a chamfer, and a chamfering process that is performed in advance before the back-grinding process. a grindstone that horizontally cuts and removes the upper part of the chamfered portion from the outer circumference to the inner circumference of the wafer to a target thickness (T), and the length of the removed machining allowance is L, and the allowance α is , when processing the wafer into a shape such that L=T/tanφ+α, where the angle of the inner surface of the wafer transport cassette that contacts the outer periphery of the wafer is φ, the outermost periphery of the wafer is polished after the processing. A wafer thinning apparatus characterized in that the angle φ is determined so that the polishing tape and the corner of the edge portion do not come into point contact.
[4] A wafer thinning device that processes a wafer to a desired thickness by back-grinding, including a chamfering device that processes the edge portion of the wafer outer periphery as a chamfer, and a chamfering device that processes the wafer outer circumferential edge portion as a chamfer, and a chamfering device that processes the wafer to a desired thickness by back-grinding. a grindstone that horizontally cuts and removes the upper part of the chamfered portion from the outer circumference to the inner circumference of the wafer to a target thickness (T), and the length of the removed machining allowance is L, and the allowance α is , the inner surface of the wafer transport cassette is processed into a shape such that L=T/tanφ+α, where the angle of the part that contacts the outer circumference of the wafer is φ, and the angle φ is the inner surface of the wafer transport cassette, and the A wafer thinning device characterized in that a point contact between an edge portion and a corner portion is determined.
[5] In a wafer that is thinned to a desired thickness by back-grinding, the edge portion of the wafer outer periphery is processed as a chamfer, and the upper part of the chamfer is thinned from the top surface of the wafer to the desired thickness ( T) is removed horizontally from the outer periphery of the wafer to the inner periphery, and the length of machining allowance removed from the outer periphery is L, the angle φ of the chamfered part with respect to the horizontal, and the margin α, L=T/tanφ+α. The wafer is processed into a shape such that the angle φ is determined so that a polishing tape for polishing the outer peripheral portion of the wafer and a corner of the edge portion do not come into point contact.
[6] In a wafer to be thinned to a desired thickness by back grinding, the edge portion of the wafer outer periphery is processed as a chamfer, and the upper part of the chamfer is formed to a desired thickness (thinned from the top surface of the wafer). T) is removed horizontally from the outer periphery of the wafer to the inner periphery, and the length of machining allowance removed from the outer periphery is L, the angle φ of the chamfered part with respect to the horizontal, and the margin α, L=T/tanφ+α. The wafer is processed into a shape such that the angle φ is determined so that the inner surface of the wafer transport cassette and the corner of the edge portion do not come into point contact.

Another aspect of the present invention is a wafer thinning method in which a wafer is processed to a desired thickness by back-grinding, wherein an edge portion of the outer periphery of the wafer is processed as a chamfered portion, and an upper portion of the chamfered portion is processed. is removed horizontally from the outer periphery of the wafer toward the inner periphery to the target thickness (T) to be thinned from the upper surface of the wafer, the length of the removal allowance removed from the outer periphery is L, and the angle of the chamfered portion with respect to the horizontal is φ , allowance α is processed into a shape such that L=T/tanφ+α, and after processing the wafer into the shape, the contact angle with a polishing tape for polishing the outermost peripheral part of the wafer and the angle φ are They were determined to be equal.

The present invention also provides a wafer thinning method in which the wafer is processed to a desired thickness by back-grinding, the edge portion of the outer periphery of the wafer being processed as a chamfered portion, and the upper part of the chamfered portion being The wafer is removed horizontally from the outer periphery to the inner periphery until the target thickness (T) is thinned from the top surface, and the length of removal from the outer periphery is L, the angle φ of the chamfered part with respect to the horizontal, and the margin α , the angle φ is determined to be equal to the angle of the portion of the inner surface of the wafer transport cassette that contacts the outer circumference of the wafer.

Furthermore, the present invention provides a wafer thinning apparatus for processing a wafer to a desired thickness by back-grinding, including a chamfering apparatus for processing an edge portion of the outer periphery of the wafer as a chamfer, and a grindstone that horizontally cuts and removes the upper part of the chamfered part that has been chamfered in advance to a target thickness (T) from the outer circumference to the inner circumference of the wafer, and the length of the machining allowance to be removed is L, The wafer is processed into a shape such that L=T/tanφ+α, where the margin α is the angle of the inner surface of the wafer transport cassette that contacts the outer circumference of the wafer, and after processing the wafer into the shape, The contact angle with the polishing tape for polishing the outermost peripheral portion of the wafer is determined to be equal to the angle φ.

The present invention also provides a wafer thinning device for processing a wafer to a desired thickness by back-grinding, including a chamfering device for processing an edge portion of the outer periphery of the wafer as a chamfer, and a grindstone that horizontally cuts and removes the upper part of the chamfered part that has been chamfered in advance to a target thickness (T) from the outer circumference to the inner circumference of the wafer, and the length of the machining allowance to be removed is L, The inner surface of the wafer transport cassette is processed into a shape such that L=T/tanφ+α, and the angle φ is the inner surface of the wafer transport cassette. The angle is determined to be equal to the angle of the portion that contacts the outer circumferential portion of the wafer.

Furthermore, in the present invention, in a wafer that is thinned to a desired thickness by back grinding, an edge portion of the outer periphery of the wafer is processed as a chamfered portion, and an upper portion of the chamfered portion is thinned from the upper surface of the wafer. The thickness (T) is removed horizontally from the outer periphery to the inner periphery of the wafer, and the length of machining allowance removed from the outer periphery is L, the angle φ of the chamfered part with respect to the horizontal, and the margin α, L=T /tanφ+α, and the angle φ is determined to be equal to the contact angle with the polishing tape that polishes the outer peripheral portion of the wafer.

Furthermore, the present invention provides a wafer that is thinned to a desired thickness by back grinding, in which an edge portion of the outer periphery of the wafer is processed as a chamfered portion, and an upper portion of the chamfered portion is thinned from the top surface of the wafer. The thickness (T) is removed horizontally from the outer periphery to the inner periphery of the wafer, and the length of machining allowance removed from the outer periphery is L, the angle φ of the chamfered part with respect to the horizontal, and the allowance α, L=T /tanφ+α, and the angle φ is determined to be equal to the angle of the portion of the inner surface of the wafer transport cassette that contacts the outer peripheral portion of the wafer.

According to the present invention, the upper part of the chamfered portion on the outer periphery of the wafer is removed horizontally from the outer periphery toward the inner periphery until the target thickness (T) for thinning is reached. Since the wafer is processed into a shape with L=T/tanφ+α, where the allowance α is taken as Back grinding can be achieved by eliminating damage to the end face. Therefore, productivity and profitability of thinned wafers can be improved.

A front view showing main parts according to an embodiment of the present invention A plan view showing main parts according to an embodiment of the present invention A cross-sectional view showing the shape of a wafer W at the time of chamfering according to an embodiment of the present invention A sectional view showing a cut made by a trimming grindstone according to an embodiment of the present invention A sectional view showing the detailed shape of the outer periphery of a wafer W according to an embodiment of the present invention A side view showing a state of contact between a wafer W and a polishing tape according to an embodiment of the present invention A diagram showing the configuration of a polishing device according to an embodiment of the present invention A sectional view showing a back grinding process and the shape of a wafer W according to an embodiment of the present invention

Embodiments of the present invention will be described in detail below with reference to the drawings. Semiconductor wafer thinning is performed by back grinding, which grinds the semiconductor wafer from the back side to the desired thickness.In the subsequent manufacturing process, the wafer's periphery is chamfered before the wafer is thinned. The edges are processed to prevent damage such as cracking and chipping during handling.

Additionally, when a chamfered wafer is thinned, the cross section of the periphery becomes more acute and becomes thinner toward the outer periphery, changing into a knife-edge shape. Before thinning, cutting is performed in advance to avoid a knife edge so that the surface is perpendicular to .

First, the chamfering device will be explained. FIG. 1 is a front view showing the main parts of a chamfering device according to an embodiment of the present invention, and FIG. 2 is a plan view.

As shown in the figure, the chamfering device 50 includes a wafer feeding unit 50A and a grinding unit 50B. A pair of Y-axis guide rails 52, 52 are laid at a predetermined interval on a horizontally disposed base plate 51 of the wafer feeding unit 50A. A Y-axis table 56 is slidably supported on the pair of Y-axis guide rails 52, 52 via Y-axis linear guides 54, 54.

A nut member 58 is fixed to the lower surface of the Y-axis table 56, and a Y-axis ball screw 60 is screwed into the nut member 58. The Y-axis ball screw 60 is rotatably supported at both ends by bearing members 62, 62 disposed on the base plate 51 between the pair of Y-axis guide rails 52, 52, and has a Y-axis ball screw 60 at one end. A shaft motor 64 is connected.

By driving the Y-axis motor 64, the Y-axis ball screw 60 rotates, and the Y-axis table 56 slides in the horizontal direction (Y-axis direction) along the Y-axis guide rails 52, 52 via the nut member 58. .

A pair of X-axis guide rails 66, 66 are laid on the Y-axis table 56 so as to be orthogonal to the pair of Y-axis guide rails 52, 52. An X-axis table 70 is slidably supported on the pair of X-axis guide rails 66, 66 via X-axis linear guides 68, 68, .

A nut member 72 is fixed to the lower surface of the X-axis table 70, and an X-axis ball screw 74 is screwed into the nut member 72. The X-axis ball screw 74 is rotatably supported at both ends by bearing members 76, 76 disposed on the X-axis table 70 between a pair of X-axis guide rails 66, 66, and one of the X-axis ball screws 74 is An output shaft of an X-axis motor (not shown) is connected to the end.

Therefore, by driving the X-axis motor, the X-axis ball screw 74 rotates, and the X-axis table 70 slides in the horizontal direction (X-axis direction) along the X-axis guide rails 66, 66 via the nut member 72. do.

A Z-axis base 80 is vertically erected on the X-axis table 70, and a pair of Z-axis guide rails 82, 82 are laid on the Z-axis base 80 at a predetermined interval. A Z-axis table 86 is slidably supported by the pair of Z-axis guide rails 82, 82 via Z-axis linear guides 84, 84.

A nut member 88 is fixed to the side surface of the Z-axis table 86, and a Z-axis ball screw 90 is screwed into the nut member 88. The Z-axis ball screw 90 has both ends rotatably supported by bearing members 92, 92 disposed on the Z-axis base 80 between a pair of Z-axis guide rails 82, 82, and a lower end thereof. The output shaft of the Z-axis motor 94 is connected to.

By driving the Z-axis motor 94, the Z-axis ball screw 90 rotates, and the Z-axis table 86 slides in the vertical direction (Z-axis direction) along the Z-axis guide rails 82, 82 via the nut member 88. . A θ-axis motor 96 is installed on the Z-axis table 86.

A θ-axis shaft 98 centered on the θ-axis (rotation axis θ) parallel to the Z-axis is connected to the output shaft of the θ-axis motor 96, and a suction table (holding table) is attached to the upper end of the θ-axis shaft 98. ) 10 are connected horizontally. The wafer W is placed on the suction table 10 and held by vacuum suction.

In the wafer feeding unit 50A, the suction table 10 moves horizontally in the Y-axis direction in the figure by driving the Y-axis motor 64, and moves horizontally in the X-axis direction in the figure by driving the X-axis motor. Then, by driving the Z-axis motor 94, it moves vertically in the Z-axis direction in the figure, and by driving the θ-axis motor 96, it rotates around the θ-axis.

A pedestal 102 is installed on the base plate 51 of the grinding unit 50B. A peripheral motor 104 is installed on the pedestal 102, and a spindle 106 whose axis is a rotation axis CH parallel to the Z-axis is connected to the output shaft of the peripheral motor 104. A grindstone wheel 108 for chamfering the outer periphery of the wafer W is detachably attached to the spindle 106 and rotated by driving the outer periphery motor 104 . A nozzle 121 is provided for discharging coolant (grinding fluid) toward the processing point where the wafer W contacts the grindstone wheel 108 .

In the chamfering apparatus 50 configured as described above, the wafer W is chamfered as follows. As a preparatory step before the chamfering process, the wafer W to be chamfered is placed on the suction table 10 and held by suction. Then, the outer peripheral motor 104 and the θ-axis motor 96 are driven to rotate both the grindstone wheel 108 and the suction table 10 at high speed in the same direction. For example, the rotation speed of the grindstone wheel 108 is set to 3000 rpm, and the rotation speed of the suction table 10 is set to such a speed that the outer peripheral speed of the wafer W is 5 mm/sec.

Further, the Z-axis motor 94 is driven to adjust the height of the suction table 10 so that the height of the wafer W corresponds to the height of the grindstone wheel 108. Further, the X-axis motor is driven to align the θ axis (rotation axis θ) serving as the rotation axis of the wafer W with the rotation axis CH of the grindstone wheel 108 in the X-axis direction.

Next, as a chamfering process, the Y-axis motor 64 is driven to send the wafer W toward the grindstone wheel 108. Then, the wafer W is decelerated just before the outer peripheral portion of the wafer W comes into contact with the grindstone wheel 108, and then the wafer W is sent toward the grindstone wheel 108 at a low speed.

As a result, the outer circumferential portion of the wafer W comes into sliding contact with the grinding wheel 108, and is ground and chamfered minute by minute as described below. In addition, coolant is discharged from the nozzle 121 toward the processing point to cool the processing point and to discharge grinding debris and abrasion powder of the grindstone (crushed and fallen abrasive grains).

Then, when the outer circumference of the wafer W reaches the deepest part of the grinding groove and a predetermined period of time has elapsed, the chamfering process is finished, and the wafer W is moved in a direction away from the grinding wheel 108 to a position where the wafer W is collected. let For chamfering and shaping, the outer periphery of the wafer is processed using a CBN or SD diamond grindstone.

FIG. 3 is a cross-sectional view showing the shape of the wafer W at the time when the chamfering process is completed. FIG. 8 is a cross-sectional view showing the back grinding process and the shape of the wafer W. The cross-sectional shape of the edge portion of the wafer W is chamfered, and the chamfered portion W-1 has a slightly rounded shape.

The wafer W is placed on the suction table 10, and while the wafer W is held, back grinding is performed to thin the wafer by grinding the back surface side as shown by the dotted line in FIG. 8 using the back grinding grindstone 21. If this continues, the edge portion W-10 will have a sharp shape due to the chamfer angle. Then, the mechanical strength becomes very weak and edge chipping occurs. In addition, the edge portion may flap due to the influence of grinding water or processing conditions, causing chipping and causing wafer damage.

In back grinding, regarding the grinding conditions, it is good for reducing edge chipping to reduce the feed speed of the back grinding whetstone 21 near the final finishing thickness to perform low load grinding for both rough grinding and finish grinding. Furthermore, edge trimming is effective, in which grooves are made in advance on the outer peripheral edge of the wafer W before the back grinding process.

However, simply grooving to a depth corresponding to the target thickness T of the wafer W after thinning will result in chipping near the final finished thickness, scratches on the outer shape when the wafer W is stored in a cassette, etc. It is difficult to reduce transportation damage and damage when polishing edges using polishing tape.

In edge trimming, the shaded area in FIG. 3 is processed using a trimming whetstone 20 before back grinding to edge trim the end face of the wafer W and remove damage. As the trimming whetstone 20, a vitrified whetstone, a resin whetstone of No. 3000 or higher, or the like is suitable. After edge trimming, minute irregularities on the ground wafer W are polished to give a mirror finish so as not to affect surface performance.

FIG. 4 is a cross-sectional view showing a cut made by the trimming whetstone 20. The upper part of the chamfered part W-1, which is the shaded part in FIG. 3, is removed from the upper surface of the wafer W by 50 to 150 μm, which corresponds to the target thickness T, and is smoothed horizontally in the Y direction. Next, by swinging in the Z direction, the rising portion W-2, which is a plane perpendicular to the incision direction, is mirror-finished to prevent cracks from entering.

This improves workability, promotes the cavitation effect, and prevents clogging at the processing point due to difficulty in coolant entering and sludge being difficult to discharge. Therefore, the cleaning of the grinding surface and the discharge of grinding debris are promoted, and the amount of protrusion of the grinding abrasive grains is stably ensured, thereby improving the processing quality.

FIG. 5 is a cross-sectional view showing the detailed shape of the outer periphery of the wafer W. L is a removal length necessary to avoid transportation damage and damage caused by the polishing tape, and is removed from the outer circumference of the wafer W toward the inner circumference. Unless the value of L is set appropriately, it will be difficult to reduce damage in the process after chamfering and improve quality.

The inner surface of the transport cassette (not shown) usually comes into contact with the outer circumference of the wafer W at a predetermined angle. φ is an angle that is chamfered to be approximately equal to the contact angle with a holder such as a transport cassette or with a polishing tape in a subsequent polishing process. φ is necessary to prevent the corner W-3 of the edge of the wafer W from coming into point contact with the inner surface of a holder such as a transport cassette or the polishing tape.

FIG. 6 is a side view showing the state of contact between the wafer W and the polishing tape 31. If the machining allowance length L to be processed is less than or equal to T/tanφ, the corner W-3 of the wafer W to be used will come into point contact with the inner surface of the transport cassette and the polishing tape 31 and collide with the corner W-3. 3, there is an increased risk of chipping. The polishing tape 31 is guided and sent out from the feed bobbin 34 by guide rollers 38 and 39. Then, the polishing tape 31 comes into contact with the outer circumference of the wafer W and is wound onto the take-up bobbin 35 via guide rollers 36 and 37.

The outermost peripheral portion W-4 of the wafer W needs to be sufficiently mirror-finished with the polishing tape 31, and minute irregularities are polished to give it a slightly rounded shape. Therefore, if α is the margin (preferably 0.1 to 0.5 mm),
It is processed into a shape such that L=T/tanφ+α.
T is the target thickness of the wafer W to be used, and φ is the chamfer angle that is approximately equal to the contact angle with the holder such as a transport cassette or the polishing tape. damage that could occur can be avoided.

FIG. 7 is a diagram showing the configuration of the polishing apparatus. The polishing apparatus includes a wafer stage 3 that holds a wafer W, a wafer stage moving mechanism 4 that moves the wafer stage 3 in a parallel direction, and an edge polishing unit 5 that serves as a polishing tape unit that polishes the edge of the wafer W. A polishing movement mechanism 6 for moving the edge polishing unit 5 relative to the edge portion of the wafer W held on the wafer stage 3 is provided.

The wafer stage moving mechanism 4 includes an axle 11 that rotatably supports the cylindrical member 30, a movable part 12 that can move together with the axle 11, and a support that movably supports the wafer stage 3 on a base 13. It is equipped with a stand 14. Note that the movable portion 12 is movable in the direction shown by arrow Y. Further, the cylindrical member 30 is configured to be rotatable about the β axis as a rotation axis.

The edge polishing unit 5 includes a polishing head section 32 as an edge contact section that brings a polishing tape (band-shaped polishing member) 31 into contact with and presses the edge of the wafer W, and a polishing tape that sends the polishing tape 31 to the polishing head section 32. A feeding mechanism 33 is provided.

The polishing tape feeding mechanism 33 includes a feeding bobbin 34 as a tape feeding section that sends the polishing tape 31 to the polishing head section 32, and a winding bobbin as a tape winding section that winds up the polishing tape 31 fed out to the polishing head section 32. 35, and a rotation mechanism (not shown) that rotates the take-up bobbin 35. As the polishing tape 31, a polishing tape whose base film is coated with abrasive grains on one side, which becomes the polishing surface, is used.

The polishing movement mechanism 6 includes a spindle 41 having a cylindrical member 40 that holds the edge polishing unit 5 consisting of a polishing head section 32 and a polishing tape feed mechanism 33, a movable part 42 that can move integrally with the spindle 41, and a movable It includes an axle 43 that supports the part 42 and a movable part 44 that can move together with the axle 43.

As described above, in addition to simply grooving the outer peripheral edge of the wafer W to a depth corresponding to the target thickness T before the back grinding process, it is also possible to groove the outer peripheral edge of the wafer W to a depth corresponding to the target thickness T. Optimum edge trimming is performed by taking into account transportation damage such as scratches on the surface of the product, or damage caused when polishing the edge using a polishing tape. This effectively prevents damage during back grinding and chipping near the final finished thickness.

In addition, when edge trimming, by swinging the trimming whetstone 20 in the Z direction, the abrasive grains are vibrated in the Z direction, adding to the original cutting ability and vibration acceleration motion of the abrasive grains, improving grinding performance. . This allows for low damage machining in the Z direction. In addition, cavitation of the abrasive grains is promoted on the side that is parallel to the cutting direction, and no damage occurs on the surface of the rising portion W-2 that is perpendicular. In addition, by dispersing the poor lubrication of the abrasive grains and the processing load, the shape maintenance performance of the grindstone is improved, and work quality can be stabilized and the life of the grindstone can be improved.

W...Wafer, W-1...Chamfer, W-2...Rising part, W-3...Corner, W-4...Outermost circumference, W-10...Edge part, φ...Chamfer angle, L...Machining allowance length T... Target thickness, α... Margin, 3... Wafer stage, 4... Wafer stage movement mechanism, 5... Edge polishing unit, 6... Polishing movement mechanism, 10... Suction table, 11, 41, 43... Axis stand , 12, 42, 44... Movable part, 13... Base, 14... Support stand, 20... Trimming whetstone, 21... Back grinding whetstone, 30... Cylindrical member, 31... Polishing tape, 32... Polishing head section, 33... Polishing tape feeding mechanism, 34... feeding bobbin, 35... winding bobbin, 36, 37, 38, 39... guide roller, 40... cylindrical member, 50... chamfering device, 50A... wafer feeding unit, 50B... grinding unit, 51... Base plate, 52... Y-axis guide rail, 54... Y-axis linear guide, 56... Y-axis table, 58, 72, 88... Nut member, 60... Y-axis ball screw, 62... Bearing member, 64... Y-axis motor, 66... X-axis guide rail, 68...X-axis linear guide, 70...X-axis table, 74...X-axis ball screw, 76, 92...bearing member, 80...Z-axis base, 82...Z-axis guide rail, 84...Z-axis linear guide , 86... Z-axis table, 90... Z-axis ball screw, 94... Z-axis motor, 96... θ-axis motor, 98... θ-axis shaft, 102... mount, 104... outer periphery motor, 106... spindle, 108... grindstone wheel, 121 …nozzle

Claims (3)

A wafer thinning method in which a wafer is processed to a desired thickness by back grinding, the method comprising:
Processing an edge portion of the outer periphery of the wafer as a chamfered portion,
removing the upper part of the chamfer from the upper surface of the wafer horizontally from the outer circumference to the inner circumference of the wafer to a target thickness (T) to be thinned;
When machining into a shape where L=T/tanφ+α, where L is the length of machining allowance removed from the outer periphery, angle φ of the chamfered part with respect to the horizontal, and allowance α,
A method for thinning a wafer, characterized in that, after the processing, the angle φ is determined so that a polishing tape for polishing the outermost peripheral portion of the wafer and a corner of the edge portion do not come into point contact. In a wafer thinning device that processes a wafer to a desired thickness by backgrinding,
a chamfering device that processes an edge portion of the outer periphery of the wafer as a chamfer;
a grinding wheel that horizontally cuts and removes the upper part of the chamfered part that has been chamfered in advance before the back grinding process to a target thickness (T) from the outer circumference of the wafer toward the inner circumference;
, where L is the length of the machining allowance to be removed, α is the allowance, and φ is the angle of the part of the inner surface of the wafer transport cassette that contacts the outer circumference of the wafer, and processed into a shape such that L=T/tanφ+α. When doing,
A wafer thinning apparatus characterized in that, after the processing, the angle φ is determined so that a polishing tape for polishing the outermost peripheral portion of the wafer and a corner of the edge portion do not come into point contact. In a wafer that is thinned to a desired thickness by back grinding,
An edge portion of the outer periphery of the wafer is processed as a chamfered portion,
The upper part of the chamfer is removed horizontally from the outer periphery of the wafer to the inner periphery of the wafer to a thinning target thickness (T) from the upper surface of the wafer,
The length of the machining allowance removed from the outer periphery is L, the angle φ of the chamfered part with respect to the horizontal, and the allowance α, and it is processed into a shape such that L=T/tanφ+α,
The wafer is characterized in that the angle φ is determined so that a polishing tape for polishing the outer peripheral portion of the wafer and a corner of the edge portion do not come into point contact.