JP2020068322A - Wafer processing method - Google Patents

Abstract

To prevent backside cracks from occurring when a wafer that has a plurality of planned dividing lines is processed on the surface.SOLUTION: A wafer processing method includes an expanding sheet attaching step of attaching an expanding sheet T to the back surface Wb of a wafer W, a cutting step of cutting the wafer W from the front surface Wa of the wafer W by a cutting blade 173 along a planned dividing line S before or after performing the expanding sheet attaching step, forming a cutting groove M, and forming an uncut portion Wc between the groove bottom of the cutting groove M and the back surface Wb of the wafer W, and a dividing step of dividing the wafer W along the dividing line S by expanding the expanding sheet T after performing the expanding sheet attaching step and the cutting step.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a method for processing a wafer having a plurality of dividing lines on its surface.

  Generally, a wafer having a device formed on the front surface is cut by a cutting device in which the back surface is attached to a tape made of a base material and a glue layer to facilitate handling after division (for example, see Patent Document 1). ) Is used for dicing.

JP, 2016-159409, A

  However, when the wafer is fully cut with a cutting blade, cracks are likely to occur because the back surface of the wafer is supported by the glue layer. In particular, when the thickness of the wafer is reduced to, for example, 80 μm or less, cracks on the back surface are significantly generated. If a crack is generated on the back surface, the crack may expand during later handling, and the chip may be damaged during mounting on a substrate or the like.

  Therefore, when processing a wafer having a plurality of planned dividing lines on the front surface, there is a problem of preventing back surface cracks from occurring.

  The present invention for solving the above-mentioned problems is a method for processing a wafer having a plurality of planned dividing lines on the front surface, and an expand sheet attaching step of attaching an expand sheet to the back surface of the wafer, and attaching the expand sheet. Before or after performing the bonding step, the wafer is cut from the front surface of the wafer along the planned dividing line with a cutting blade to form a cutting groove and left uncut between the groove bottom of the cutting groove and the back surface of the wafer. A cutting step of forming a part, a step of adhering the expanded sheet and a step of cutting, and then a step of dividing the wafer along the dividing line by expanding the expanded sheet. This is a wafer processing method.

  It is preferable that the uncut portion is set to a thickness that is not damaged by the cutting of the cutting blade and that can be divided in the expanding step.

  The method for processing a wafer according to the present invention is an expanding sheet attaching step of attaching an expanding sheet to the back surface of the wafer, and before or after performing the expanding sheet attaching step, from the front surface of the wafer with a cutting blade to a dividing line. The wafer is cut (half cut) along the above to form a cutting groove and a cutting step of forming an uncut portion between the bottom of the cutting groove and the back surface of the wafer, an expanding sheet attaching step and a cutting step. After carrying out, it is possible to divide the wafer without full cutting with the cutting blade by providing a dividing step of applying an external force to the wafer by expanding the expanded sheet and dividing the wafer along the dividing line. , There is no risk of backside cracking.

It is a perspective view which shows an example of a wafer. FIG. 6 is a perspective view showing an example of a wafer to which an expand sheet is attached and which is supported by an annular frame. It is a perspective view showing an example of a cutting device. A cross section for explaining a state in which a wafer is cut from the front surface of the wafer with a cutting blade along a dividing line to form a cutting groove and an uncut portion is formed between the groove bottom of the cutting groove and the back surface of the wafer. It is a figure. It is sectional drawing which expands and shows a part of wafer in which the uncut part was formed. It is a perspective view showing an example of an expanding device which expands an expanding sheet radially. It is sectional drawing which shows the state which mounted the wafer supported by the cyclic | annular frame on the 2nd holding member of an expander. It is sectional drawing which shows the state by which the annular frame was clamped and fixed by the 1st holding member and the 2nd holding member. FIG. 6 is a cross-sectional view showing a state where the expand sheet is expanded by the expander and the wafer is divided along the dividing line. It is sectional drawing which expands and shows a part of wafer divided into the chip provided with a device. It is sectional drawing explaining the state which expanded expansion of the expanded seat was cancelled | released. A cross section for explaining a state in which a wafer is cut from the front surface of the wafer with a cutting blade along a dividing line to form a cutting groove and an uncut portion is formed between the groove bottom of the cutting groove and the back surface of the wafer. It is a figure. It is a perspective view explaining the state where the wafer was stuck to the square-shaped expanded sheet. It is a perspective view which shows an example of the expander which expands an expand sheet | seat in all directions. It is a perspective view showing the state where the expand sheet is expanded in all directions. It is sectional drawing which shows the state which has expanded the expand sheet | seat in all directions. It is a perspective view explaining the state where the annular frame is stuck to the expanded expand sheet. It is a sectional view explaining the state where the expanded sheet is cut according to the annular frame.

(Embodiment 1)
Each of the processing methods when the wafer processing method according to the present invention (hereinafter referred to as the processing method of the first embodiment) is carried out to divide the wafer W shown in FIG. 1 into chips each including the device D will be described below. The steps will be described.
The wafer W shown in FIG. 1 is, for example, a semiconductor wafer having silicon as a base material and having a circular outer shape, and its front surface Wa is divided into a plurality of dividing lines S that are orthogonal to each other in a grid shape. A device D such as an IC is formed in each of the divided areas.
The wafer W may be made of gallium arsenide, sapphire, gallium nitride, silicon carbide, or the like other than silicon.

(1) Expanding Sheet Adhering Step As shown in FIG. 2, the expanding sheet T is adhered to the back surface Wb of the wafer W. The expanded sheet T is, for example, a circular sheet having a certain degree of stretchability against a mechanical external force and having a diameter larger than that of the wafer W. The expanded sheet T has a base material Td made of synthetic resin or the like enlarged in FIG. It consists of an adhesive layer Tc on Td. For the glue layer Tc, for example, a UV curable glue that is cured by irradiation with ultraviolet rays to reduce the adhesive strength may be used.

For example, the annular frame F is positioned with respect to the wafer W so that the center of the wafer W placed on a bonding table (not shown) and the center of the opening of the annular frame F shown in FIG. Then, the glue layer Tc of the expanded sheet T is pressed and stuck to the back surface Wb of the wafer W by a press roller or the like on the sticking table. At the same time, the wafer W is supported by the annular frame F via the expanding sheet T by adhering the outer peripheral portion of the glue layer Tc of the expanding sheet T to the annular frame F, so that the wafer W can be handled by the annular frame F. become. Note that the expand sheet T may be attached to the annular frame F after the expand sheet T is attached to only the wafer W first by a press roller or the like and then the wafer W is appropriately positioned with respect to the annular frame F. Alternatively, after the long sheet pulled out from the tape roll is attached to the annular frame F and the wafer W, the sheet may be cut into a circle by a cutter.
The expanding sheet attaching process may be performed after the wafer W is cut (half cut) by itself.

(2) Cutting Step The wafers W, which can be handled by the annular frame F, are transferred to the cutting device 1 while being housed in the cassette 111 shown in FIG.
A cassette mounting table 110 is installed at one corner on the −Y direction side on the base 10 of the cutting device 1 shown in FIG. 3, and the cassette mounting table 110 is installed by an elevator (not shown) arranged below the cassette mounting table 110. It can move up and down in the Z-axis direction. With the cassette 111 accommodating a plurality of wafers W placed on the cassette mounting table 110, the elevation position of the cassette mounting table 110 is moved up and down by the elevator so that the height position when the wafer W is taken in and out of the cassette 111 is Adjusted.

A centering guide 113 for aligning the wafer W drawn from the cassette 111 by a push-pull (not shown) to a certain position is provided at a position facing the loading / unloading port on the + Y direction side of the cassette 111 on the base 10. There is. The centering guide 113 includes a pair of guide rails each having an L-shaped cross section and extending in the Y-axis direction. The guide rails can be separated from or approach each other in the X-axis direction and have a stepped shape. The guide surfaces (inner side surfaces) are arranged so as to face each other. When the cutting process of the wafer W is started, the wafer W is pulled out from the cassette 111 by a push-pull (not shown) and placed on the centering guide 113. The wafer W that has been cleaned after processing is placed on the centering guide 113 and then pushed into the cassette 111 by push-pull (not shown).
A push-pull (not shown) that pulls out the wafer W before cutting from the cassette 111 while holding the annular frame F in the vertical direction is capable of reciprocating in the Y-axis direction.

  The cutting apparatus 1 includes a holding table 130 that holds the wafer W by suction, and the holding table 130 is rotatable about the axis in the Z-axis direction. Further, the holding table 130 can be reciprocated in the cutting feed direction (X-axis direction) by a cutting feed means (not shown) arranged below the expanding and contracting bellows cover 132. The cutting feed means is a ball screw mechanism that cuts and feeds the holding table 130 by rotating a ball screw with a motor.

  The holding table 130 shown in FIG. 3 has, for example, a circular outer shape, and is provided with a substantially flat holding surface 130a which is connected to a suction source and is made of a porous member or the like to suck and hold the wafer W. For example, as shown in FIG. 4, a plurality of clamps 131 for sandwiching and fixing the annular frame F are arranged around the holding table 130 at equal intervals in the circumferential direction.

  As shown in FIG. 3, on the rear side (−X direction side) of the base 10, a gate column 14 is erected so as to straddle the moving path of the holding table 130. On the front surface of the gate-shaped column 14, index feeding means 12 for reciprocating the cutting means 17 for cutting the wafer W in the Y-axis direction is arranged. The index feeding means 12 includes a ball screw 120 having an axis in the Y-axis direction, a pair of guide rails 121 arranged in parallel with the ball screw 120, a motor 122 for rotating the ball screw 120, and an internal nut having a ball screw 120. The movable plate 123 is screwed onto the side surface of the movable plate 123 and is in sliding contact with the guide rail 121. Then, when the motor 122 rotates the ball screw 120, the movable plate 123 is guided by the guide rail 121 and moves in the Y-axis direction accordingly, and the movable plate 123 is disposed on the movable plate 123 via the slit feed means 15. The cutting means 17 is index-fed in the Y-axis direction.

  On the movable plate 123, the cutting feed means 15 for moving the cutting means 17 back and forth in the Z-axis direction (vertical direction) orthogonal to the holding surface 130a of the holding table 130 is arranged. The cutting feed means 15 includes a ball screw 150 having an axis in the Z-axis direction, a pair of guide rails 151 arranged parallel to the ball screw 150, a motor 152 for rotating the ball screw 150, and an internal nut having a ball screw 150. And a support member 153 whose side portion is in screw contact with the guide rail 151. Then, when the motor 152 rotates the ball screw 150, the support member 153 is guided by the guide rail 151 and moves in the Z-axis direction accordingly, and the cutting means 17 supported by the support member 153 cuts and feeds in the Z-axis direction. To be done.

  The cutting means 17 includes a rotary shaft 170 whose axial direction is the Y-axis direction, a housing 171 fixed to the lower end of the support member 153 to rotatably support the rotary shaft 170, and a motor (not shown) that rotates the rotary shaft 170. An annular cutting blade 173 attached to the rotating shaft 170 is provided, and the cutting blade 173 also rotates at high speed as a motor (not shown) rotationally drives the rotating shaft 170.

  In the vicinity of the cutting means 17, an alignment means 18 for detecting the planned dividing line S of the wafer W held on the holding table 130 to be cut is arranged. The alignment means 18 can detect the coordinate position of the planned dividing line S by performing image processing such as pattern matching based on a captured image acquired by a camera (not shown). The alignment means 18 and the cutting means 17 are integrally formed, and both move in the Y-axis direction and the Z-axis direction in conjunction with each other.

  In the cutting step, the wafer W is cut by the cutting blade 173 from the front surface Wa of the wafer W along the planned dividing line S to form a cutting groove, and the cutting groove is cut between the groove bottom and the back surface Wb of the wafer W. The remaining part is formed. The cutting step may be performed before the expanding sheet attaching step.

  That is, first, the wafer W is placed on the holding surface 130a of the holding table 130 with the front surface Wa facing upward. Then, the suction force generated by a suction source (not shown) is transmitted to the holding surface 130a, so that the holding table 130 sucks and holds the wafer W on the holding surface 130a. Further, as shown in FIG. 4, the annular frame F is clamped and fixed by the clamp 131.

  After the wafer W is held by the holding table 130, a cutting feed unit (not shown) feeds the wafer W held by the holding table 130 in the −X direction, and the alignment unit 18 executes image processing such as image capturing and pattern matching. Then, the coordinate position of the planned dividing line S to be cut by the cutting blade 173 is detected. As the coordinate position of the planned dividing line S is detected, the cutting means 17 is moved in the Y-axis direction by the index feeding means 12, and the planned dividing line S and the cutting blade 173 are aligned in the Y-axis direction. Be seen.

After the above alignment, the holding table 130 holding the wafer W is further fed in the −X direction at a predetermined cutting feed rate. Further, the cutting feed means 15 lowers the cutting means 17 in the −Z direction, and the cutting means 17 is positioned at a predetermined height position where the lowermost end of the cutting blade 173 does not cut through the back surface Wb of the wafer W.
A motor (not shown) rotates the rotary shaft 170 at high speed in the clockwise direction when viewed from the −Y direction (front side of the paper surface) as shown in FIG. 4, and the cutting blade 173 fixed to the rotary shaft 170 is accompanied by this. The wafer W is cut while rotating at a high speed, and the planned dividing line S is cut (half cut) to form the cutting groove M and the uncut portion Wc shown in FIG. In addition, cutting water is sprayed onto the contact portion between the cutting blade 173 and the wafer W and the periphery thereof, and the contact portion (processing point) is cooled and washed.

  The thickness of the uncut portion Wc is set according to the material and type of the wafer W (dividability of device pattern), wafer thickness, chip size and the like. Further, the uncut portion Wc is set to have a thickness that is not damaged by the cutting of the cutting blade 173 and can be divided in the dividing step described later. That is, the thickness is a thickness that does not cause cracks in the uncut portion Wc due to the impact transmitted from the cutting blade 173 to the wafer W at the time of half-cutting, and is set to a thickness that can be divided by the external force applied by the sheet expanding in the dividing step described later. To do. The thickness of the uncut portion Wc is, for example, about 5 μm to 50 μm, and when the thickness of the silicon wafer W is 80 μm, it is set to, for example, about 20 μm.

  When the cutting blade 173 illustrated in FIG. 4 advances the wafer W in the −X direction to a predetermined position in the X-axis direction at which the cutting of one planned dividing line S is completed, the cutting feed of the wafer W is stopped once, and the cutting blade 173 illustrated in FIG. The cutting feed means 15 shown in (1) separates the cutting blade 173 from the wafer W, and then the cutting feed means 13 feeds the holding table 130 in the + X direction to return it to the original position. The cutting means 17 is index-fed in the Y-axis direction at intervals of the adjacent planned dividing lines S, and the same cutting is sequentially performed to cut all the planned dividing lines S in the same direction. Further, when the holding table 130 is rotated by 90 degrees and the same cutting is performed, the cutting groove M and the uncut portion Wc can be formed on the wafer W along all the planned dividing lines S.

(3) Dividing Step The wafer W that has been subjected to the cutting process is transferred to the expanding device 8 shown in FIG. 6, for example. The expanding device 8 shown in FIG. 6 is a device that breaks the wafer W along the dividing line S by using the force when the expanding sheet T is expanded, and includes a frame holding means 80 that holds the annular frame F. At least a sheet expanding unit 81 for expanding the expanded sheet T to which the annular frame F held by the frame holding unit 80 is attached, and a holding table 82 for sucking and holding the wafer W are provided.

  The frame holding means 80 includes, for example, a first holding member 801 having a rectangular shape in plan view, and a second holding member 802 that holds and clamps the annular frame F in the vertical direction together with the first holding member 801. The first holding member 801 and the second holding member 802 are made of, for example, a metal material such as SUS, and are arranged in a state of being vertically opposed to each other. Openings 801a and 802a having the same diameter are formed respectively.

  Then, as shown in FIG. 7, in the annular frame F, between the first holding member 801 and the second holding member 802, the opening of the annular frame F, the opening 801a of the first holding member 801, and the The opening 802a of the second holding member 802 is arranged with the centers thereof aligned with each other, and is sandwiched and fixed by the first holding member 801 and the second holding member 802 from above and below. An area around the opening 801a in the lower surface of the first holding member 801 and an area around the opening 802a in the upper surface of the second holding member 802 function as a holding surface for holding the annular frame F. To do.

As shown in FIG. 6, the first holding member 801 is fixed so as to face above the second holding member 802.
The second holding member 802 is connected to piston rods 803a of four air cylinders 803 (only three are shown in FIG. 6, and only two are shown in FIG. 7) and is supported by the air cylinders 803 so as to be vertically movable. Has been done.

  The sheet expanding means 81 disposed inside the second holding member 802 shown in FIGS. 6 and 7 includes a cylindrical expansion drum 810 that abuts against the expansion sheet T from below when the expansion sheet T is expanded, and the expansion drum 810. And an elevating mechanism 811 such as an air cylinder for vertically moving the. As shown in FIG. 7, a plurality of rollers 812 are attached to the upper end surface of the expansion drum 810. The outer diameter of the expansion drum 810 is set smaller than the diameter of the opening of the annular frame F and larger than the outer diameter of the wafer W, for example. As shown in FIG. 7, the center of the expansion drum 810 and the center of the opening 802a of the second holding member 802 are substantially aligned with each other. The roller 812 plays a role of reducing the frictional resistance generated when the expanded sheet T is pressed from below and expanding the expanded sheet T, so that the expanding force acts evenly.

  In the standby state where the sheet expanding means 81 does not act on the expanded sheet T, the lifting mechanism 811 causes the roller 812, which is the upper end of the expansion drum 810, to be below the holding surface (upper surface) of the second holding member 802. It is located in position.

  The holding table 82 is arranged in the cylinder of the expansion drum 810 and has a circular plate-shaped outer shape. The upper surface of the holding table 82, which is made of a porous member or the like, is a substantially flat holding surface 82a that communicates with the suction portion 89 and suction-holds the wafer W. The holding table 82 can be moved up and down in the Z-axis direction by table lifting means 88 such as an air cylinder.

  In the dividing step, first, the frame holding means 80 holds the annular frame F. That is, as shown in FIG. 7, the upper surface of the second holding member 802 is arranged so that the center of the wafer W supported by the annular frame F and the center of the opening 802a of the second holding member 802 are substantially aligned with each other. An annular frame F is placed on top. Subsequently, as shown in FIG. 8, the second holding member 802, the expansion drum 810, and the holding table 82, which are separated from the first holding member 801, and face each other, are lifted toward the first holding member 801 side. By doing so, the annular frame F is sandwiched between the first holding member 801 and the second holding member 802. The method for holding the annular frame F in the sandwiched state is not limited to the above. For example, the annular frame F is sandwiched by lowering the first holding member 801 toward the second holding member 802. It may be allowed to.

  Further, as shown in FIG. 8, the roller 812 at the upper end portion of the expansion drum 810 comes into contact with the ring-shaped region between the outer periphery of the wafer W of the expanded sheet T and the inner periphery of the annular frame F from below. Further, the holding surface 82a of the holding table 82 is in contact with the back surface Wb of the wafer W via the expanded sheet T.

  Next, as shown in FIG. 9, the elevating mechanism 811 raises the expansion drum 810 to a predetermined height position, whereby the expansion drum 810 presses the expanded sheet T and pushes it upward. As a result, the expanded sheet T is radially expanded, an external force is applied to the wafer W attached to the expanded sheet T, and the wafer W is cut from the uncut portion Wc along the planned dividing line S, and the individual chips are separated. It is divided into C. Further, the expanded sheet T is stretched until the adjacent chips C are completely separated from each other, and as shown in FIG. 10, a predetermined interval is formed between the plurality of chips C to prevent damage due to contact of the chips C. .

  Note that, for example, the holding table 82 may be a heating table with a built-in surface heater, and the expanding surface T of the holding table 82 may be brought into contact with the expanding sheet T when the expanding sheet T is expanded, for example, at about 80 degrees. As a result, the expanded sheet T is softened and easily expanded.

  Further, as shown in FIG. 9, the table elevating means 88 raises the holding table 82 so that the holding surface 82a of the holding table 82 contacts the back surface Wb of the wafer W divided into the chips C through the expand sheet T. It will be in the state of doing. Then, the suction force generated by the operation of the suction portion 89 is transmitted to the holding surface 82a, so that the wafer W is suction-held on the holding surface 82a, and the slack due to the release of the expansion of the expand sheet T described later is chipped. It is set so that it does not occur between C (to maintain the distance between the chips C after expansion).

  In this state, when the expansion drum 810 is lowered to release the expansion of the expanded sheet T and the holding table 82 is lowered, as shown in FIG. 11, the outer circumference of the wafer W of the expanded sheet T and the annular frame F are expanded. A slack portion Tf is formed as a surplus in a ring-shaped region between the inner periphery and the inner periphery. Since the wafer W is held by suction on the holding table 82, the interval between the adjacent chips C is maintained in the state of division.

  For example, a far infrared heater (not shown) that heats and contracts the slack portion Tf of the expanded sheet T is provided above the holding table 82 shown in FIG. 11. Then, the far-infrared heater orbits around the slack portion Tf around the axis in the Z-axis direction at a predetermined orbiting speed, so that the slack portion Tf of the expanded sheet T is heated and contracted to return to a flat state. Be done.

  As described above, the wafer processing method according to the present invention is performed by the cutting blade 173 before or after performing the expanding sheet attaching step of attaching the expanding sheet T to the back surface Wb of the wafer W and the expanding sheet attaching step. The wafer W is cut (half cut) from the front surface Wa of the wafer W along the planned dividing line S to form a cutting groove M, and an uncut portion Wc is formed between the groove bottom of the cutting groove M and the back surface Wb of the wafer W. After performing the cutting step for forming the sheet, the expanding sheet attaching step and the cutting step, the expanding sheet T is expanded to apply an external force to the uncut portion Wc of the wafer W to divide the wafer W along the planned dividing line S. The wafer W is divided without being fully cut by the cutting blade 173. Rukoto can, also not to generate cracks in the back surface Wb.

(Embodiment 2)
Each of the processing methods when the wafer processing method according to the present invention (hereinafter, referred to as the processing method of the second embodiment) is carried out to divide the wafer W shown in FIG. The steps will be described.

(1) Cutting Step In the second embodiment, the cutting step is first performed before the expanding sheet attaching step. The cutting step is performed in substantially the same manner as in the first embodiment. That is, the wafer W is transferred to the holding table 130 of the cutting device 1 shown in FIG. 3 and suction-held on the holding surface 130 a of the holding table 130. After the wafer W is held by the holding table 130, the holding table 130 is sent in the −X direction, alignment of the planned dividing line S and alignment of the planned dividing line S to be cut with the cutting blade 173 in the Y-axis direction are performed. Done.

  After the above alignment, the holding table 130 holding the wafer W is further fed in the −X direction at a predetermined cutting feed rate. Further, the cutting means 17 is positioned so that the rotating cutting blade 173 is at a predetermined height position where it does not pass through the back surface Wb of the wafer W. Then, as shown in FIG. 12, the cutting blade 173 rotates at a high speed to cut (half-cut) the planned dividing line S into the wafer W to form the cutting groove M and the groove bottom of the cutting groove M shown in FIG. The uncut portion Wc between the back surface Wb of the wafer W is formed along all the planned dividing lines S. The thickness of the uncut portion Wc is set, for example, as in the first embodiment.

(2) Expanding Sheet Attaching Step Next, the expanding sheet T2 shown in FIG. 13 is attached to the back surface Wb of the wafer W that has been subjected to the cutting process. The expanded sheet T2 has a pressure-sensitive adhesive layer formed by adhering the wafer W on one surface, such as a synthetic resin sheet having expandability such as polyvinyl chloride (PVC) or polyolefin (PO). It has a larger square outer shape.

  For example, the expand sheet T2 is positioned with respect to the wafer W such that the center of the wafer W placed on a sticking table (not shown) and the center of the expand sheet T2 substantially coincide with each other. Then, the adhesive layer of the expanded sheet T2 is pressed and adhered to the back surface Wb of the wafer W by a press roller or the like on the application table.

(3) Dividing Step The wafer W to which the expanding sheet T2 is attached is transported to the expanding device 2 shown in FIG. 14, for example.
The expanding device 2 shown in FIG. 14 is an example of a device that can sandwich and pull the four sides of the expanded sheet T2 attached to the wafer W. The expanding device 2 has a fixed base 20 having a square shape in a plan view, and a holding table 3 is supported at the center of the upper surface of the fixed base 20 via a cylindrical base 30. The holding table 3 is supported on the cylindrical base 30 by a rotating mechanism (not shown) so as to be rotatable about the axis in the Z-axis direction, and vertically movable on the cylindrical base 30 by a vertical moving mechanism (not shown). The upper surface of the holding table 3 has a diameter on which the wafer W can be placed, and the expanded sheet T2 to which the wafer W is attached is held in a state where the wafer W is arranged on the upper side and is arranged concentrically. It is placed on the upper surface of the table 3.

  At the center of each outer edge of the four sides of the fixed base 20, a rectangular convex portion 201 protruding outward is formed. A rectangular first guide groove 201a, a second guide groove 201b, a third guide groove 201c, and a fourth guide groove 201d that extend along the direction in which each protrusion 201 extends are formed on each protrusion 201. There is.

  As shown in FIG. 14, the X-axis direction in which a pair of outer edges of the fixed base 20 which are parallel to each other extends is defined as a first direction, and the Y-axis direction orthogonal to the first direction is defined as a second direction. On the fixed base 20, the first holding means 4A and the second holding means 4B, which are arranged to face each other in the first direction and respectively hold the expanded sheet T2, are arranged to face each other in the second direction. In addition, a third holding means 4C and a fourth holding means 4D for holding the expanded sheet T2 are provided.

  From the respective convex portions 201 of the fixed base 20 to the periphery of the holding table 3 on the fixed base 20, the first to fourth holding means 4A to 4D are provided, and the first to second holding means 4A to. 4A, a first moving means 5A, a second moving means 5B, and third to fourth holding means 4C to 4D, respectively, a third moving means 5C and a fourth moving means. 5D is provided.

  The first to fourth clamping means 4A to 4D have the same configuration, and a movable base 41 having a substantially L-shape in a side view and incorporated so as to be movable along the first to fourth guide grooves 201a to 201d, respectively. A lower sandwiching mechanism 42 and an upper sandwiching mechanism 43, which are vertically movably attached to the inside of the movable base 41, and a lower moving mechanism 44 and an upper side which move the lower sandwiching mechanism 42 and the upper sandwiching mechanism 43 in the vertical direction, respectively. And a moving mechanism 45.

  The movable base 41 includes a slide portion 411 slidably fitted in each of the first to fourth guide grooves 201a to 201d, and a support portion erected at the outer end of the slide portion 411 in the Z-axis direction. It consists of 412.

  A guide rail 412a extending in the vertical direction is formed on the inner surface of the support portion 412. A guide groove 412b extending in the vertical direction is formed on the outer surface of the support portion 412. Further, the support portion 412 is formed with a guide hole 412c extending from the inner surface of the guide rail 412a to the guide groove 412b and extending in the vertical direction.

  The first to fourth moving means 5A to 5D for moving the first to fourth holding means 4A to 4D along the first to fourth guide grooves 201a to 201d have the same configuration and are arranged inside the slide portion 411. It has a ball screw 51 that is screwed into a provided nut and extends along each of the first to fourth guide grooves 201a to 201d, and a motor 52 that is disposed in the convex portion 201 and that drives the ball screw 51 to rotate forward and backward. ing. The tip of the ball screw 51 is rotatably supported by bearings 53 fixed to the outer sides of the first to fourth guide grooves 201a to 201d on the fixed base 20, respectively.

  The slide portion 411 of the movable base 41 to which the ball screw 51 is screwed is arranged from the outside to the inside along each of the first to fourth guide grooves 201a to 201d according to the rotation direction of the ball screw 51 which is rotationally driven by the motor 52, or It is sent from the inside to the outside, whereby the first holding means 4A and the second holding means 4B are reciprocated in the first direction, and the third holding means 4C and the fourth holding means 4D are reciprocated in the second direction. .

  In the example of FIG. 14, each of the first sandwiching means 4A and the second sandwiching means 4B is movable in the first direction, but only one of the first sandwiching means 4A and the second sandwiching means 4B is the first. It may be configured to be capable of reciprocating in one direction. Further, each of the third holding means 4C and the fourth holding means 4D is movable in the second direction, but only one of the third holding means 4C and the fourth holding means 4D reciprocates in the second direction. It may be movable.

  The lower holding mechanism 42 includes an arm portion 421 that is supported along the guide rail 412a so as to be vertically movable and extends toward the inside, and a lower holding portion that is fixed to the tip of the arm portion 421 orthogonal to the arm portion 421. 422 is formed in a substantially T shape in a plan view. The base end portion 421c on the rear end side of the arm portion 421 penetrates the guide hole 412c and is disposed in the outer guide groove 412b.

  The lower sandwiching portions 422 of the first sandwiching means 4A and the second sandwiching means 4B extend in parallel with the second direction, and the lower sandwiching portions 422 of the third sandwiching means 4C and the fourth sandwiching means 4D are respectively first. It extends parallel to the direction. The lower holding portion 422 is formed in a rectangular parallelepiped shape, and a plurality of rollers 423 are arranged close to each other on the upper surface thereof. The rollers 423 of the first sandwiching means 4A and the second sandwiching means 4B are supported by the lower sandwiching portion 422 so as to be rotatable about the axis in the first direction, and the rollers of the third sandwiching means 4C and the fourth sandwiching means 4D. 423 is supported by the lower holding portion 422 so as to be rotatable around the axis in the second direction. About half of the outer peripheral surface of the roller 423 projects from the upper surface of the lower holding portion 422.

  The upper sandwiching mechanism 43 disposed above the lower sandwiching mechanism 42 has a configuration that is substantially vertically and horizontally symmetrical to the lower sandwiching mechanism 42, and is supported so as to be vertically movable along the guide rail 412a and is inwardly moved. A substantially T-shape in a plan view, which includes an arm portion 431 that extends toward the front side and an upper holding portion 432 that is fixed to the tip of the arm portion 431 at right angles to the arm portion 431 and that is arranged to face the lower holding portion 422. Is formed in. The base end portion 431c on the rear end side of the arm portion 431 penetrates the guide hole 412c and is disposed in the outer guide groove 412b.

  The upper holding parts 432 of the first holding means 4A and the second holding means 4B extend parallel to the second direction, and the upper holding parts 432 of the third holding means 4C and the fourth holding means 4D run parallel to the first direction. It is extended. The upper holding portion 432 is formed in a rectangular parallelepiped shape, and a plurality of rollers 433 are arranged close to each other on the lower surface thereof, as shown in FIG. Note that, in FIG. 15, the roller 433 inside the upper holding portion 432 is made visible so as to be simplified. These rollers 433 are arranged so as to face the rollers 423 of the lower sandwiching portion 422 shown in FIG. 14, and the rollers 433 of the first sandwiching means 4A and the second sandwiching means 4B rotate around the axis in the first direction. Is rotatably supported by the upper clamping unit 432, and the rollers 433 of the third clamping unit 4C and the fourth clamping unit 4D are rotatably supported by the upper clamping unit 432 about the axis in the second direction. About half of the outer peripheral surface of the roller 433 projects from the lower surface of the upper holding portion 432.

  The lower holding mechanism 42 and the upper holding mechanism 43 shown in FIG. 14 are reciprocated in the vertical direction on the inner side surface of the support portion 412 along the guide rails 412a by the lower moving mechanism 44 and the upper moving mechanism 45, respectively. .

  The lower moving mechanism 44 is disposed at the lower end portion of the guide groove 412b and the ball screw 441 which is screwed into the base end portion 421c of the arm portion 421 and extends vertically along the guide groove 412b. And a motor 442 that is rotationally driven. The upper end of the ball screw 441 is rotatably supported by a bearing 443 fixed in the guide groove 412b. The base end portion 421c with which the ball screw 441 is screwed is fed vertically along the guide groove 412b in accordance with the rotation direction of the ball screw 441 that is rotationally driven by the motor 442, whereby the lower holding mechanism 42 is moved up and down. .

  The upper moving mechanism 45 disposed on the upper side of the lower moving mechanism 44 has a configuration that is substantially vertically symmetrical with the lower moving mechanism 44, is screwed into the base end portion 431c of the arm portion 431, and is guided by the guide groove 412b. It has a ball screw 451 extending in the up-and-down direction along with, and a motor 452 arranged at the upper end of the support portion 412 and driving the ball screw 451 to rotate forward and backward. The lower end of the ball screw 451 is rotatably supported by a bearing 453 fixed in the guide groove 412b. The base end portion 431c with which the ball screw 451 is screwed is fed up and down along the guide groove 412b according to the rotation direction of the ball screw 451 that is rotationally driven by the motor 452, whereby the upper holding mechanism 43 is moved up and down.

  As shown in FIG. 14, the expanding device 2 includes a control means 29 for controlling each component of the device. The control unit 29 including a CPU, a storage element, and the like is electrically connected to each lower moving mechanism 44, each upper moving mechanism 45, the first to fourth moving units 5A to 5D, and the like.

  For example, each of the motors 52 of the above-mentioned first to fourth moving means 5A to 5D is a pulse motor that operates by a drive pulse supplied from a pulse oscillator (not shown). The control means 29 counts the number of drive pulses supplied to each motor 52 of the first to fourth moving means 5A to 5D, and sequentially expands the expanding force of the expand sheet T2 by the first to fourth sandwiching means 4A to 4D. Can be adjusted.

  The motors 52 of the first to fourth moving means 5A to 5D may be servo motors, and a rotary encoder may be connected to the servo motors. The rotary encoder is connected to the control means 29 which also has a function as a servo amplifier. After the operation signal is supplied from the control means 29 to the servo motor, the encoder signal (the rotation speed of the servo motor) is controlled by the control means 29. Output to. The control means 29 can sequentially adjust the expansion force of the expanded seat T2 by the first to fourth sandwiching means 4A to 4D based on the received encoder signal.

  For example, an ammeter for detecting the load current value of the electric power supplied to each motor 52 of the first to fourth moving means 5A to 5D is provided, and the current value information of the motor 52 is sent from the ammeter to the control means 29. You may be allowed to. Then, during operation of the first to fourth moving means 5A to 5D, a current value is detected as a load applied to the motor 52, and the control means 29 uses the information received from the ammeter to determine the first to fourth clamping means 4A to 4D. The expansion force of the expanding sheet T2 due to can be sequentially adjusted.

  In the dividing step, first, on the upper surface of the holding table 3 shown in FIG. 14, the expanded sheet T2 to which the wafer W shown in FIG. 13 is attached is placed with the wafer W on the upper side and concentrically. Place at. The upper surface of the holding table 3 is located at an intermediate position between the lower holding portion 422 of the lower holding mechanism 42 of the first to fourth holding means 4A to 4D and the upper holding portion 432 of the upper holding mechanism 43, for example. Positioned at height.

  Next, the first to fourth moving means 5A to 5D are operated to appropriately move the first and second holding means 4A and 4B in the first direction, and the third and fourth holding means 4C and 4D are moved to the second position. By appropriately moving in the direction between the lower sandwiching portion 422 of each lower sandwiching mechanism 42 and the upper sandwiching portion 432 of each upper sandwiching mechanism 43, the lower sandwiching portion 422 and the upper sandwiching portion 432 expand the expansion sheet T2. Each of the first to fourth clamping means 4A to 4D is positioned at a position where the end edge of each of them can be clamped. Then, the lower-side moving mechanism 44 and the upper-side moving mechanism 45 are operated to raise the lower-side holding portions 422 and lower-side the upper-side holding portions 432, and as shown in FIG. 15, the expanded sheet T2 is horizontal. In this state, the rollers 423 and 433 of the lower holding portion 422 and the upper holding portion 432 hold the four edges of the expanded sheet T2.

  The upper and lower rollers 433, 423 of each of the first to fourth holding means 4A to 4D hold the state in which the four edges of the expanded sheet T2 are held, and then the first to fourth moving means 5A to 5D. Is operated to move the first and second holding means 4A, 4B outward in the first direction so as to separate them from each other, as shown in FIG. 15, to expand the expanded sheet T2 in the first direction, and at the same time, The third and fourth clamping means 4C, 4D are moved outward in the second direction so as to separate from each other, and the expandable sheet T2 is expanded in the second direction.

  As a result, an external force is applied to the wafer W attached to the expanded sheet T2, the wafer W is cut along the dividing line S from the uncut portion Wc, and divided into individual chips C as shown in FIG. To be done. Further, the expanded sheet T2 is stretched until the adjacent chips C are completely separated from each other, and a predetermined interval is formed between the plurality of chips C to prevent damage due to contact of the chips C.

Next, the annular frame F is positioned with respect to the wafer W such that the center of the wafer W and the center of the opening of the annular frame F shown in FIG. 17 are substantially aligned with each other while the expansion of the expanded sheet T2 is maintained. After that, the annular frame F descends and is pressed and attached to the adhesive layer of the expanding sheet T2 on the holding table 3 (not shown in FIG. 17).
Note that, for example, a roller that rolls above the holding table 3 is provided, and after the holding table 3 descends and separates from the expanding sheet T2, the base material side of the expanding sheet T2 corresponding to the annular frame F is rolled. By rolling, the expanded sheet T2 may be pressed and attached to the annular frame F from the −Z direction side.

  For example, as shown in FIG. 18, after the holding table 3 is lowered and separated from the expanded sheet T2, the cutter 27 is positioned below the expanded sheet T2. The cutter 27 pivots about the axis in the Z-axis direction and moves so as to draw a circle on the expanded sheet T2 corresponding to the annular frame F, and cuts the expanded sheet T2 into a circle in accordance with the annular frame F.

  As described above, the wafer processing method according to the present invention is performed by the cutting blade 173 before or after performing the expanding sheet attaching step of attaching the expanding sheet T2 to the back surface Wb of the wafer W and the expanding sheet attaching step. The wafer W is cut (half cut) from the front surface Wa of the wafer W along the planned dividing line S to form a cutting groove M, and an uncut portion Wc is formed between the groove bottom of the cutting groove M and the back surface Wb of the wafer W. After performing the cutting step for forming the sheet, the expanding sheet attaching step and the cutting step, the expanding sheet T2 is expanded to apply an external force to the uncut portion Wc of the wafer W to divide the wafer W along the dividing line S. By providing a dividing step of dividing the wafer W into pieces, the wafer W is not fully cut by the cutting blade 173. Can be split, it is also not to generate cracks in the back surface Wb.

  It goes without saying that the wafer processing method according to the present invention is not limited to the above-described first and second embodiments, and may be carried out in various different forms within the scope of the technical idea thereof. Further, the external shapes and sizes of the respective components of the cutting device 1, the expanding device 8 and the expanding device 2 shown in the accompanying drawings are not limited to this, and are within the range in which the effects of the present invention can be exerted. It can be changed as appropriate.

W: Wafer Wa: Wafer front surface S: Divided line D: Device Wb: Wafer back surface T: Expanded sheet F: Annular frame M: Cutting groove Wc: Uncut portion 1: Cutting device 10: Base 14: Gate type Column 130: Holding table 131: Clamp 12: Index feeding means 15: Cutting feeding means 17: Cutting means 170: Rotating shaft 173: Cutting blade 18: Alignment means 8: Expanding device
80: Frame holding means 801: First holding member 802: Second holding member 803: Air cylinder 81: Sheet expanding means 810: Expansion drum 811: Lifting mechanism 812: Roller 82: Holding table 88: Table lifting means T2: Expanding seat 2: Expanding device 20: Fixed base 201: Convex part 29: Control means 4A-4D: 1st-4th clamping means 41: Movable base 411: Slide part 412: Support part 412a: Guide rail 412b: Guide Groove 412c: Guide hole 42: Lower holding mechanism 421: Arm portion 422: Lower holding portion 423: Roller 43: Upper holding mechanism 431: Arm portion 432: Upper holding portion 433: Roller 44: Lower moving mechanism 441: Ball screw 442: Motor 443: Bearing 45: Upper moving mechanism 451: Ball screw 45 : Motor 453: Bearing 5A-5D: first to fourth moving means 51: ball screw 52: motor 53: Bearing

Claims (2)

A method of processing a wafer having a plurality of planned dividing lines on the surface,
An expanding sheet attaching step of attaching an expanding sheet to the back surface of the wafer,
Before or after performing the expanding sheet attaching step, a wafer is cut along the dividing line from the front surface of the wafer with a cutting blade to form a cutting groove and the groove bottom of the cutting groove and the back surface of the wafer. A cutting step to form an uncut portion between
A method of processing a wafer, comprising: performing the expanding sheet attaching step and the cutting step, and then dividing the wafer along the dividing line by expanding the expanding sheet.   The method for processing a wafer according to claim 1, wherein the uncut portion is set to have a thickness that can be divided in the expanding step without being damaged by the cutting of the cutting blade.