JP6808525B2 - Wafer processing method - Google Patents

Description

The present invention relates to a method for processing a wafer in which a plurality of devices are partitioned by a scheduled division line and a wafer formed on the surface is divided into individual devices.

A wafer in which a plurality of devices such as ICs and LSIs are partitioned by a planned division line and formed on the surface is divided into individual devices by a dicing device equipped with a cutting blade, and each divided device is a mobile phone, a personal computer, etc. Used for electrical equipment.

In order to increase the speed of the device, a plurality of Low-k films (low dielectric constant insulator coatings) are laminated on the surface of a semiconductor substrate such as a silicon wafer to form circuits such as ICs and LSIs. The Low-k film is also laminated on the planned division line, and when cut with a cutting blade, it peels off like a mica, which has the problem of degrading the quality of the device. Therefore, a laser beam is irradiated along the planned division line. A technique has been proposed in which a Low-k film is removed by forming a laser-machined groove, a cutting blade is positioned in the laser-machined groove, dicing is performed, and a wafer is divided into individual devices, and the technique has been put into practical use (see Patent Document 1). .).

However, the technique disclosed in Patent Document 1 below includes the following problems.
(1) Even if the width of the laser processing groove is sufficient, the cutting blade comes into contact with the melt adhering to the side surface of the laser processing groove, and the outer periphery of the device is suddenly chipped.
(2) If the removal of the Low-k film by forming the laser processing groove is insufficient, the cutting blade is displaced or tilted, and the Low-k film of the device is peeled off.
(3) Since a laser machining groove having a width exceeding the width of the cutting blade is formed, a wide scheduled division line is required, and the number of devices to be taken is reduced.

Therefore, the applicant positions the cutting blade from the back surface of the wafer to the region corresponding to the planned division line by the dicing device to form a cutting groove that does not reach the surface of the wafer, and then a laser beam from the back surface of the wafer along the cutting groove. We have proposed a technique for cutting a Low-k film by irradiating with (see Patent Document 2).

Japanese Unexamined Patent Publication No. 2005-64231 Japanese Unexamined Patent Publication No. 2015-126504

However, in the technique disclosed in Patent Document 2, after forming a cutting groove on the back surface of the wafer, the wafer is damaged along the cutting groove when the wafer is carried out from the dicing device and transported to the laser processing device. There is a problem.

An object of the present invention made in view of the above facts is that a wafer in which a Low-k film is laminated on the surface and a plurality of devices are formed in a region partitioned by a planned division line can be divided into individual devices without damaging the wafer. It is to provide a processing method for wafers.

In order to solve the above problems, the present invention provides the following wafer processing method. That is, it is a method of processing a wafer in which a plurality of devices are partitioned by a scheduled division line and the wafer formed on the surface is divided into individual devices, and the surface of the first wafer and the surface of the second wafer are made to face each other. The surface of the first wafer is integrated by interposing an adhesive layer, and the cutting blade is positioned in the area corresponding to the planned division line formed from the back surface of the first wafer to the surface of the first wafer. The cutting blade is located in the area corresponding to the first cutting groove forming step of forming the first cutting groove having a depth not reaching the depth of the wafer and the planned division line formed from the back surface of the second wafer to the front surface of the second wafer. A second cutting groove forming step of forming a second cutting groove having a depth that does not reach the surface of the second wafer, and irradiating a laser beam from the back surface of the first wafer along the first cutting groove. Then, the first cutting step of cutting the planned division line of the first wafer and the laser beam irradiating from the back surface of the second wafer along the second cutting groove to cut the planned division line of the second wafer. This is a method for processing a wafer, which includes at least a second cutting step.

Preferably, after the integration step, a back surface grinding step of grinding the back surface of the first wafer to thin the first wafer and grinding the back surface of the second wafer to thin the second wafer. Is included. In the integration step, it is preferable to integrate the scheduled division line formed on the surface of the first wafer and the scheduled division line formed on the surface of the second wafer so as to intersect with each other. It is convenient that the intersecting angle is approximately 45 degrees. The adhesive layer used in the integration step has thermocurability, and after the second cutting step, an adhesive layer curing step of heating the integrated wafer to cure the adhesive layer, and a first It is preferable to include a separation step of attaching a dicing tape to the back surface of the wafer and attaching the dicing tape to the back surface of the second wafer to separate the first wafer and the second wafer.

The method for processing a wafer provided by the present invention includes an integration step in which the surface of the first wafer and the surface of the second wafer face each other and are integrated with an adhesive layer interposed therebetween, and a first from the back surface of the first wafer. With the first cutting groove forming step in which the cutting blade is positioned in the region corresponding to the planned division line formed on the surface of one wafer and the first cutting groove having a depth not reaching the surface of the first wafer is formed. , Position the cutting blade in the area corresponding to the planned division line formed from the back surface of the second wafer to the surface of the second wafer to form a second cutting groove with a depth that does not reach the surface of the second wafer. The second cutting groove forming step, the first cutting step of irradiating a laser beam from the back surface of the first wafer along the first cutting groove to cut the planned division line of the first wafer, and the second. Since it is configured to include at least a second cutting step of irradiating a laser beam from the back surface of the wafer along the second cutting groove to cut the planned division line of the second wafer, the first wafer and the wafer are configured. The second wafer and the wafer reinforce each other so that the wafer is not damaged during transportation from the dicing apparatus to the laser processing apparatus.

(A) A perspective view of the first wafer and the second wafer, (b) a perspective view showing a state in which the integration process is performed, and (c) a perspective view of the integrated wafer. The perspective view which shows the state which the back surface grinding process is carried out. (A) A perspective view showing a state in which the first cutting groove forming step is performed, and (b) a cross-sectional view of an integrated wafer in which the first cutting groove is formed. (A) A perspective view showing a state in which the second cutting groove forming step is performed, and (b) a cross-sectional view of an integrated wafer in which the second cutting groove is formed. A perspective view of an integrated wafer in which a first cutting groove and a second cutting groove are formed. (A) A perspective view showing a state in which the first cutting step is performed, and (b) a cross-sectional view of an integrated wafer in which the planned division line of the first wafer is cut. (A) A perspective view showing a state in which the second cutting step is being carried out, and (b) a cross-sectional view of the integrated wafer in which the planned division line of the second wafer is cut. The perspective view which shows the state which the separation process is carried out.

Hereinafter, embodiments of the wafer processing method of the present invention will be described with reference to the drawings.

FIG. 1A shows a disk-shaped first wafer 2 and a second wafer 4 that can be formed from a silicon substrate or the like. The surface 2a of the first wafer 2 on which a plurality of Low-k films (not shown) are laminated is divided into a plurality of rectangular regions by a grid-like division schedule line 6, and each of the plurality of rectangular regions is divided into a plurality of rectangular regions. Is formed with devices 8 such as ICs and LSIs. A notch 10 indicating the crystal orientation is formed on the peripheral edge of the first wafer 2, and a line 6 scheduled to be divided is formed on the surface 2a of the first wafer 2 with the notch 10 as a reference of the orientation. Further, the surface 4a of the second wafer 4 on which a plurality of Low-k films (not shown) are laminated is also divided into a plurality of rectangular regions by a grid-like division schedule line 12, and the plurality of rectangular regions are divided. Devices 14 such as ICs and LSIs are formed in each of them. A notch 16 indicating the crystal orientation is also formed on the peripheral edge of the second wafer 4, and a planned division line 12 is formed on the surface 4a of the second wafer 4 with the notch 16 as a reference of the orientation.

In the illustrated embodiment, as shown in FIG. 1B, first, the surface 2a of the first wafer 2 and the surface 4a of the second wafer 4 are made to face each other, and the first wafer 2 is interposed via the adhesive layer 18. And the second wafer 4 are integrated with each other. FIG. 1 (c) shows a wafer 20 in which the first wafer 2 and the second wafer 4 are integrated (hereinafter referred to as “integrated wafer 20”). In the integration step, the first wafer 2 and the second wafer 4 are integrated in a state where the radial center of the first wafer 2 and the radial center of the second wafer 4 are aligned. Further, in the integration step, the first wafer 2 and the second wafer 4 are integrated so that the planned division line 6 of the first wafer 2 and the scheduled division line 12 of the second wafer 4 intersect. It is preferable to do so. In the illustrated embodiment, as shown in FIG. 1 (c), a line segment connecting the center O of the integrated wafer 20 to the notch 10 of the first wafer 2 and the center O of the integrated wafer 20 to the second wafer 4 The angle formed by the line segment connecting the notches 16 is approximately 45 degrees, and therefore the angle at which the planned division line 6 of the first wafer 2 and the planned division line 12 of the second wafer 4 intersect is approximately 45 degrees. .. When the planned division line 6 of the first wafer 2 and the planned division line 12 of the second wafer 4 intersect, the planned division line 6 of the first wafer 2 and the planned division line of the second wafer 4 Compared with the case where 12 is consistent, the first wafer 2 and the second wafer 4 reinforce each other more effectively. Further, the adhesive layer 18 to which a liquid resin adhesive or double-sided tape can be used preferably has thermosetting property. When the adhesive layer 18 has thermosetting property, the first wafer 2 and the second wafer 4 are easily separated by heating the integrated wafer 20 to cure the adhesive layer 18 and lower the adhesive force. can do.

After performing the integration process, the back surface 2b of the first wafer 2 is ground to thin the first wafer 2, and the back surface 4b of the second wafer 4 is ground to thin the second wafer 4. Carry out the backside grinding process. The back surface grinding step can be performed, for example, by using the grinding device 22 whose part is shown in FIG. The grinding device 22 includes a chuck table 24 for holding the workpiece and a grinding means 26 for grinding the workpiece held on the chuck table 24. The chuck table 24 configured to attract the workpiece on the upper surface is rotated about an axis extending in the vertical direction by a rotating means (not shown). The grinding means 26 includes a cylindrical spindle 28 connected to a motor (not shown) and extending in the vertical direction, and a disk-shaped wheel mount 30 fixed to the lower end of the spindle 28. An annular grinding wheel 34 is fixed to the lower surface of the wheel mount 30 by bolts 32. A plurality of grinding wheels 36 arranged in an annular shape at intervals in the circumferential direction are fixed to the outer peripheral edge of the lower surface of the grinding wheel 34. As shown in FIG. 2, the rotation center of the grinding wheel 34 is displaced with respect to the rotation center of the chuck table 24 so that the grinding wheel 36 passes through the rotation center of the chuck table 24. Therefore, when the chuck table 24 and the grinding wheel 34 rotate with each other and the upper surface of the workpiece held on the upper surface of the chuck table 24 and the grinding wheel 36 come into contact with each other, the entire upper surface of the workpiece is exposed. It is ground by the grinding wheel 36.

Continuing the description with reference to FIG. 2, in the back surface grinding step, first, the back surface 2b of the first wafer 2 is turned upward, and the integrated wafer 20 is attracted to the upper surface of the chuck table 24 of the grinding device 22. Next, the chuck table 24 is rotated by the rotating means at a predetermined rotation speed (for example, 300 rpm) counterclockwise when viewed from above. Further, the spindle 28 is rotated by a motor at a predetermined rotation speed (for example, 6000 rpm) counterclockwise when viewed from above. Next, the spindle 28 is lowered by an elevating means (not shown) of the grinding device 22, and the grinding wheel 36 is brought into contact with the back surface 2b of the first wafer 2. After the grinding wheel 36 is brought into contact with the back surface 2b of the first wafer 2, the spindle 28 is lowered at a predetermined grinding feed rate (for example, 1.0 μm / s). As a result, the back surface 2b of the first wafer 2 can be ground to thin the first wafer 2. Next, the second wafer 4 is thinned by the same procedure as the procedure for thinning the first wafer 2. That is, after the integrated waiha 20 is attracted to the upper surface of the chuck table 24 with the back surface 4b of the second waha 4 facing upward, the chuck table is rotated counterclockwise at a predetermined rotation speed (for example, 300 rpm) when viewed from above. The 24 is rotated by the rotating means, and the spindle 28 is rotated by the motor at a predetermined rotation speed (for example, 6000 rpm) counterclockwise when viewed from above. Next, the spindle 28 is lowered by the elevating means of the grinding device 22, and the grinding wheel 36 is brought into contact with the back surface 4b of the second wafer 4. After the grinding wheel 36 is brought into contact with the back surface 4b of the second wafer 4, the spindle 28 is lowered at a predetermined grinding feed rate. As a result, the back surface 4b of the second wafer 4 can be ground to thin the second wafer 4.

After performing the back surface grinding step, the cutting blade is positioned from the back surface 2b of the first wafer 2 to the region corresponding to the planned division line 6 formed on the surface 2a of the first wafer 2, and the first wafer 2 The first cutting groove forming step of forming the first cutting groove having a depth not reaching the surface 2a is carried out. The first cutting groove forming step can be carried out, for example, by using the dicing device 38 shown in FIG. 3A as a part thereof. The dicing device 38 includes a chuck table 40 that holds the workpiece, a cutting means 42 that cuts the workpiece held by the chuck table 40, and an imaging means (imaging means) that images the workpiece held by the chuck table 40. (Not shown). The chuck table 40 configured to attract the workpiece on the upper surface is rotated about an axis extending in the vertical direction by the rotating means, and is relatively moved in the X direction with respect to the cutting means 42. It advances and retreats in the X direction, and advances and retreats in the Y direction by the moving means in the Y direction (neither is shown). The cutting means 42 comprises a cylindrical spindle housing 44 extending substantially horizontally and a cylindrical spindle (not shown) built in the spindle housing 44 rotatably about an axis extending substantially horizontally. Including. A motor (not shown) is connected to the base end of the spindle, and an annular cutting blade 46 is fixed to the tip of the spindle. The upper part of the cutting blade 46 is covered with the blade cover 48. The imaging means include a normal imaging element (CCD) that images the work piece with visible light, an infrared irradiation means that irradiates the work piece with infrared rays, an optical system that captures the infrared rays radiated by the infrared irradiation means, and optics. It includes an image pickup element (infrared CCD) that outputs an electric signal corresponding to the infrared rays captured by the system (neither is shown). The X direction is the direction indicated by the arrow X in FIG. 3A, and the Y direction is the direction indicated by the arrow Y in FIG. 3A and is orthogonal to the X direction. The plane defined by the X and Y directions is substantially horizontal.

Continuing the description with reference to FIG. 3A, in the first cutting groove forming step, first, the back surface 2b of the first wafer 2 is turned upward and integrated with the upper surface of the chuck table 40 of the dicing device 38. The chemical wafer 20 is adsorbed. Next, the integrated wafer 20 is imaged from above by the imaging means of the dicing device 38. Next, the chuck table 40 is moved and rotated by the X-direction moving means, the Y-direction moving means, and the rotating means of the dicing device 38 based on the image of the integrated wafer 20 captured by the imaging means, thereby causing the first wafer. The planned division line 6 of 2 is aligned in the X direction and the Y direction, and the cutting blade 46 is positioned above one end of the region corresponding to the planned division line 6 aligned in the X direction. At this time, the back surface 2b of the first wafer 2 is directed upward, and the surface 2a on which the planned division line 6 is formed is directed downward. As described above, the imaging means includes the infrared irradiation means and the infrared irradiation means. Since it includes an optical system that captures infrared rays and an image sensor (infrared CCD) that outputs an electric signal corresponding to infrared rays, it is possible to image the planned division line 6 of the front surface 2a through the back surface 2b of the first wafer 2. it can. Next, the cutting blade 46 is rotated by the motor together with the spindle in the direction indicated by the arrow A in FIG. 3A. Next, the spindle housing 44 is lowered by an elevating means (not shown) of the dicing device 38, and the back surface 2b to the front surface 2a of the first wafer 2 are placed in a region corresponding to the planned division line 6 of the first wafer 2. The cutting edge of the cutting blade 46 is cut to a depth that does not reach (that is, a depth that does not reach the Low-k film), and the chuck table 40 is machined and fed in the X direction by the X direction moving means at a predetermined machining feed rate. By doing so, as shown in FIGS. 3A and 3B, the depth corresponding to the region from one end to the other end of the planned division line 6 of the first wafer 2 does not reach the front surface 2b from the back surface 2b. The first cutting process for forming the first cutting groove 50 is performed. Next, the integrated wafer 20 and the cutting blade 46 are index-fed relatively in the Y direction by the interval of the planned division line 6 of the first wafer 2. In the illustrated embodiment, in the index feed, the cutting blade 46 is index-feeded in the Y direction by the Y-direction moving means by the interval of the planned division line 6 of the first wafer 2. Then, by alternately repeating the first cutting process and the index feed, the first cutting process is performed on all the regions corresponding to the planned division lines 6 of the first wafer 2 aligned in the X direction. Further, after rotating the chuck table 40 by 90 degrees by the rotating means of the dicing device 38, the first cutting process and the index feed are alternately repeated, so that the planned division line in which the first cutting process is performed first is performed. The first cutting process is also applied to all the regions corresponding to the planned division line 6 orthogonal to the region corresponding to 6. As a result, as shown in FIG. 5, the depth from the back surface 2b of the first wafer 2 to the surface 2a does not reach the region corresponding to the grid-like division scheduled line 6 formed on the surface 2a of the first wafer 2. The first cutting groove 50 can be formed in a grid pattern.

This will be described with reference to FIG. After performing the first cutting groove forming step, the cutting blade is positioned from the back surface 4b of the second wafer 4 to the region corresponding to the planned division line 12 formed on the front surface 4a of the second wafer 4, and the second cutting blade is positioned. A second cutting groove forming step of forming a second cutting groove having a depth not reaching the surface 4a of the wafer 4 is carried out. The second cutting groove forming step can be carried out using the dicing device 38 described above. In the second cutting groove forming step, first, the integrated wafer 20 is attracted to the upper surface of the chuck table 40 of the dicing apparatus 38 with the back surface 4b of the second wafer 4 facing upward. Next, the integrated wafer 20 is imaged from above by the imaging means of the dicing device 38. Then, based on the image of the integrated wafer 20 captured by the imaging means, the chuck table 40 is moved and rotated by the X-direction moving means, the Y-direction moving means, and the rotating means of the dicing device 38, thereby causing the second wafer. The planned division line 12 of 4 is aligned in the X direction and the Y direction, and the cutting blade 46 is positioned above one end of the region corresponding to the planned division line 12 aligned in the X direction. At this time, the back surface 4b of the second wafer 4 is directed upward, and the surface 4a on which the planned division line 12 is formed is directed downward. As described above, the imaging means includes the infrared irradiation means and the infrared irradiation means. Since it includes an optical system that captures infrared rays and an image sensor (infrared CCD) that outputs an electric signal corresponding to infrared rays, it is possible to image the planned division line 12 of the front surface 4a through the back surface 4b of the second wafer 4. it can. Next, the cutting blade 46 is rotated by the motor together with the spindle in the direction indicated by the arrow A in FIG. 4A. Next, the spindle housing 44 is lowered by the elevating means of the dicing device 38, and the depth corresponding to the planned division line 12 of the second wafer 4 is not reached from the back surface 4b of the second wafer 4 to the front surface 4a (that is,). , The cutting edge of the cutting blade 46 is cut to a depth that does not reach the Low-k film), and the chuck table 40 is machined and fed in the X direction by the X direction moving means at a predetermined machining feed rate. As shown in a) and (b), a second cutting groove 52 having a depth not reaching the front surface 4a from the back surface 4b in the region corresponding to one end to the other end of the planned division line 12 of the second wafer 4. Perform a second cutting process to form. Next, the integrated wafer 20 and the cutting blade 46 are index-fed relatively in the Y direction by the interval of the scheduled division line 12 of the second wafer 4. In the illustrated embodiment, in the index feed, the cutting blade 46 is index-feeded in the Y direction by the Y-direction moving means by the interval of the planned division line 12 of the second wafer 4. Then, by alternately repeating the second cutting process and the index feed, the second cutting process is performed on all the regions corresponding to the planned division lines 12 of the second wafer 4 aligned in the X direction. Further, after rotating the chuck table 40 by 90 degrees by the rotating means of the dicing device 38, the second cutting process and the index feed are alternately repeated, so that the planned division line in which the second cutting process is performed first is performed. The second cutting process is also performed on all the regions corresponding to the planned division line 12 orthogonal to the region corresponding to 12. As a result, the second cutting groove 52 having a depth not reaching the front surface 4a from the back surface 4b of the second wafer 4 in the region corresponding to the grid-like division scheduled line 12 formed on the surface 4a of the second wafer 4. Can be formed in a grid pattern.

After performing the second cutting groove forming step, a laser beam is irradiated from the back surface 2b of the first wafer 2 along the first cutting groove 50 to cut the planned division line 6 of the first wafer 2. Carry out the cutting process of. The first cutting step can be carried out, for example, by using the laser processing apparatus 54 shown in FIG. 6A as a part thereof. The laser machining apparatus 54 includes a chuck table 56 that holds the workpiece, and a condenser 58 that irradiates the workpiece held by the chuck table 56 with a pulsed laser beam LB. The chuck table 56 configured to attract the workpiece on the upper surface is rotated about an axis extending in the vertical direction by the rotating means, and is moved back and forth in the X direction by the moving means in the X direction to move in the Y direction. Moves forward and backward in the Y direction (neither is shown). The condenser 58 includes a condenser lens (none of which is shown) for condensing the pulse laser beam LB oscillated from the pulse laser beam oscillator of the laser processing apparatus 54 and irradiating the workpiece. The X direction is the direction indicated by the arrow X in FIG. 6A, and the Y direction is the direction indicated by the arrow Y in FIG. 6A and orthogonal to the X direction. The plane defined by the X and Y directions is substantially horizontal.

Continuing the description with reference to FIG. 6A, in the first cutting step, first, the back surface 2b of the first wafer 2 is turned upward and integrated with the upper surface of the chuck table 56 of the laser processing apparatus 54. The wafer 20 is adsorbed. Next, the integrated wafer 20 is imaged from above by the imaging means (not shown) of the laser processing apparatus 54. Then, based on the image of the integrated waiver 20 captured by the imaging means, the chuck table 56 is moved and rotated by the X-direction moving means, the Y-direction moving means, and the rotating means of the laser processing apparatus 54, thereby forming a grid pattern. The first cutting groove 50 is aligned in the X and Y directions, and the concentrator 58 is positioned above one end of the first cutting groove 50 aligned in the X direction. Next, the condenser 58 is moved up and down by the condensing point position adjusting means (not shown) of the laser processing device 54, and the condensing point is positioned at the lower end of the first cutting groove 50. Next, the first wafer 2 is moved along the first cutting groove 50 from one end to the other end of the first cutting groove 50 while moving the integrated wafer 20 and the condensing point relatively in the X direction. A pulsed laser beam LB having absorbency is irradiated from the condenser 58 to perform a first ablation process for cutting the scheduled division line 6. In the illustrated embodiment, in the first ablation process, the chuck table 56 is processed and fed in the X direction by the X direction moving means at a predetermined processing feed rate with respect to the condensing point without moving the condensing point. Next, the integrated wafer 20 and the condensing point are relatively indexed in the Y direction by the distance of the first cutting groove 50. In the illustrated embodiment, in the index feed, the chuck table 56 is index-fed in the Y direction by the Y-direction moving means with respect to the condensing point without moving the condensing point by the interval of the first cutting groove 50. ing. Then, by alternately repeating the first ablation process and the index feed, the first ablation process is performed on all of the first cutting grooves 50 aligned in the X direction. Further, after rotating the chuck table 56 by 90 degrees by the rotating means, the first ablation process and the index feed are alternately repeated to obtain the first cutting groove 50 which has been subjected to the first ablation process first. All of the first cutting grooves 50 that are orthogonal to each other are also subjected to the first ablation process. As a result, the planned division line 6 of the first wafer 2 can be cut from the back surface 2b of the first wafer 2 along the first cutting groove 50. The portion where the planned division line 6 of the first wafer 2 is cut by the first ablation processing (laser processing groove formed at the lower end of the first cutting groove 50) is shown by reference numeral 60 in FIG. 6 (b).

This will be described with reference to FIG. After performing the first cutting step, a laser beam is irradiated from the back surface 4b of the second wafer 4 along the second cutting groove 52 to cut the planned division line 12 of the second wafer 4. Carry out the process. The second cutting step can be carried out using the laser processing apparatus 54 described above. In the second cutting step, first, the integrated wafer 20 is attracted to the upper surface of the chuck table 56 of the laser processing apparatus 54 with the back surface 4b of the second wafer 4 facing upward. Next, the integrated wafer 20 is imaged from above by the imaging means of the laser processing apparatus 54. Then, based on the image of the integrated waiver 20 captured by the imaging means, the chuck table 56 is moved and rotated by the X-direction moving means, the Y-direction moving means, and the rotating means of the laser processing apparatus 54, thereby forming a grid pattern. The second cutting groove 52 is aligned in the X direction and the Y direction, and the concentrator 58 is positioned above one end of the second cutting groove 52 aligned in the X direction. Next, the condenser 58 is moved up and down by the condensing point position adjusting means of the laser processing device 54, and the condensing point is positioned at the lower end of the second cutting groove 52. Next, the second wafer 4 is moved along the second cutting groove 52 from one end to the other end of the second cutting groove 52 while moving the integrated wafer 20 and the condensing point relatively in the X direction. A second ablation process is performed in which a pulsed laser beam LB having absorbency is irradiated from the condenser 58 to cut the scheduled division line 12. In the illustrated embodiment, in the second ablation process, the chuck table 56 is processed and fed in the X direction by the X direction moving means at a predetermined processing feed rate with respect to the condensing point without moving the condensing point. Next, the integrated wafer 20 and the condensing point are relatively indexed in the Y direction by the distance of the second cutting groove 52. In the illustrated embodiment, in the index feed, the chuck table 56 is index-fed in the Y direction by the Y-direction moving means with respect to the condensing point without moving the condensing point by the distance of the second cutting groove 52. ing. Then, by alternately repeating the second ablation process and the index feed, the second ablation process is performed on all of the second cutting grooves 52 aligned in the X direction. Further, after rotating the chuck table 56 by 90 degrees by the rotating means, the second ablation process and the index feed are alternately repeated to obtain the second cutting groove 52 which has been subjected to the second ablation process first. The second ablation process is also applied to all of the second cutting grooves 52 that are orthogonal to each other. As a result, the planned division line 12 of the second wafer 4 can be cut along the second cutting groove 52 from the back surface 4b of the second wafer 4. The portion where the scheduled division line 12 of the second wafer 4 is cut by the second ablation processing (laser processing groove formed at the lower end of the second cutting groove 52) is shown by reference numeral 62 in FIG. 7 (b).

After carrying out the second cutting step, the adhesive layer curing step of heating the integrated wafer 20 to cure the adhesive layer 18 is carried out. As described above, when the adhesive layer 18 used in the integration step has thermosetting property, the integrated wafer 20 is heated to cure the adhesive layer 18 and reduce the adhesive force, whereby the first wafer 2 is used. And the second wafer 4 can be easily separated.

That is, it will be described with reference to FIG. After performing the adhesive layer curing step, the dicing tape is attached to the back surface 2b of the first wafer 2 and the dicing tape is attached to the back surface 4b of the second wafer 4, and the first wafer 2 and the second wafer 2 are attached. A separation step for separating the wafer 4 is performed. In the illustrated embodiment, a dicing tape 66 whose peripheral edge is fixed to the back surface 64b of the annular frame 64 is used. The annular frame 64 is formed with a first notch 68 having a substantially right angle and a second notch 70 having an acute angle, and the first notch 68 and the second notch 70 are formed to form an annular frame 64. The front surface 64a and the back surface 64b of the frame 64 can be easily identified. Further, four flat portions 72 extending linearly are formed on the outer peripheral edge of the annular frame 64. As shown in FIG. 8, in the separation step, first, one dicing tape 66 is attached to the back surface 2b of the first wafer 2, and the other dicing tape 66 is attached to the back surface 4b of the second wafer 4. .. Next, one annular frame 64 and the other annular frame 64 are separated from each other in the vertical direction. As a result, the first wafer 2 and the second wafer 4 can be separated. When one dicing tape 66 is attached to the back surface 2b of the first wafer 2 and the other dicing tape 66 is attached to the back surface 4b of the second wafer 4, the first annular frame 64 is attached. By positioning the notch 10 of the first wafer 2 between the one notch 68 and the second notch 70, the first cutting groove 50 and the laser machined groove 60 in a grid pattern are formed in the flat portion 72 of the annular frame 64. By positioning the notch 16 of the second wafer 4 between the first notch 68 and the second notch 70 of the other annular frame 64, the second cutting groove 52 in a grid pattern and By aligning the laser machined groove 62 with the flat portion 72 of the annular frame 64, the individual devices 8 and 14 are picked up by an appropriate picking means (not shown) with the flat portion 72 as a reference, thereby performing the pick-up operation. Can be easily performed.

As described above, in the wafer processing method of the present invention, the first wafer 2 and the second wafer 4 reinforce each other, and the first wafer 2 is transported from the dicing apparatus 38 to the laser processing apparatus 54. And the second wafer 4 is not damaged.

2: First wafer 2a: Front surface 2b: Back surface 4: Second wafer 4a: Front surface 4b: Back surface 6: Scheduled division line (first wafer)
8: Device (first wafer)
12: Scheduled division line (second wafer)
14: Device (second wafer)
18: Adhesive layer 46: Cutting blade 50: First cutting groove 52: Second cutting groove LB: Pulse laser beam 66: Dicing tape

Claims (5)

It is a processing method of a wafer in which a plurality of devices are partitioned by a scheduled division line and the wafer formed on the surface is divided into individual devices.
An integration process in which the surface of the first wafer and the surface of the second wafer face each other and are integrated with an adhesive layer.
The cutting blade is positioned in the region corresponding to the planned division line formed from the back surface of the first wafer to the surface of the first wafer to form a first cutting groove having a depth that does not reach the surface of the first wafer. The first cutting groove forming process and
The cutting blade is positioned in the region corresponding to the planned division line formed on the front surface of the second wafer from the back surface of the second wafer to form a second cutting groove having a depth that does not reach the surface of the second wafer. The second cutting groove forming process and
The first cutting step of irradiating a laser beam from the back surface of the first wafer along the first cutting groove to cut the planned division line of the first wafer, and
A second cutting step of irradiating a laser beam from the back surface of the second wafer along the second cutting groove to cut the planned division line of the second wafer, and
A method of processing a wafer that includes at least. After the integration step
The wafer according to claim 1, further comprising a back surface grinding step of grinding the back surface of the first wafer to thin the first wafer and grinding the back surface of the second wafer to thin the second wafer. Processing method. The processing of the wafer according to claim 1, wherein in the integration step, the planned division line formed on the surface of the first wafer and the planned division line formed on the surface of the second wafer are integrated so as to intersect with each other. Method. The method for processing a wafer according to claim 3, wherein the intersecting angle is approximately 45 degrees. The adhesive layer used in the integration step has thermosetting property and is thermosetting.
After the second cutting step, an adhesive layer curing step of heating the integrated wafer to cure the adhesive layer, and
The first aspect of claim 1, wherein a dicing tape is attached to the back surface of the first wafer and a dicing tape is attached to the back surface of the second wafer to separate the first wafer and the second wafer. Wafer processing method.