JP6814574B2 - How to attach the tape - Google Patents

Description

The present invention relates to a tape attaching method for attaching a tape to a wafer.

A semiconductor wafer is provided with, for example, a device region and an outer peripheral surplus region surrounding the device region on the surface thereof, and the device region is divided into a plurality of regions by scheduled division lines arranged in a grid pattern. , Devices such as ICs are formed in each of the grid-like regions. As a processing method for dividing such a semiconductor wafer into individual chips, there is a cutting method in which the wafer is cut with a rotating cutting blade, or a wafer is irradiated with a laser beam to form a modified layer inside the wafer and then modified. There are a method of applying an external force to the layer or a method of cutting the wafer by ablation processing by laser irradiation. Further, as a processing method for thinning the wafer to a certain thickness, there is a grinding method in which a rotating grinding wheel is brought into contact with the wafer to perform grinding. In these processing methods, a tape that usually plays a role of protecting the wafer and preventing the divided chips from scattering apart is attached to the wafer, and a holding table or the like is attached via this tape. Various processing is applied to the wafer held in.

For example, in recent years, in order to achieve weight reduction and miniaturization of a device, it is required in a wafer grinding method to make the thickness of the wafer thinner, for example, about 50 μm. However, such a thinly formed wafer becomes stiff and difficult to handle, and may be damaged during wafer transportation or the like. Therefore, as a grinding method for improving the handleability while grinding the wafer very thinly, the region corresponding to the device region of the wafer in the back surface of the wafer is ground to form a circular recess to surround the device region. A grinding method has been proposed in which an annular convex portion for reinforcement is formed in a region on the back surface of a wafer corresponding to an outer peripheral surplus region (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2007-019461

When the tape is attached to the back surface of the wafer on which the annular convex portion is formed by grinding, the tape does not completely adhere to the stepped portion between the circular concave portion and the annular convex portion, and the tape floats from the back surface of the wafer. There is a gap between the tape and the wafer. Then, when there is a gap between the tape being attached to the wafer and the processing of the wafer to be performed next, this gap gradually widens, and the tape is lifted up to the part where the tape was attached to the wafer. The phenomenon of coming occurs. If, for example, cutting is performed on the wafer while the tape is lifted more widely, the tip that has not been attached to the tape due to the tape lift will be blown off by the rotating cutting blade. There is a problem that the number of chips obtained is reduced, or the skipped chips collide with other chips and the other chips are damaged. The lifting of the tape from the wafer and the spread of the lifting that cause such a problem occur remarkably in the wafer that has been ground so as to form an annular convex portion on the outer peripheral portion, but the entire back surface of the wafer is flat. Even in a wafer that has been subjected to normal grinding, it may occur over time after the tape is attached to the flat back surface of the wafer.

Therefore, when the tape is attached to the wafer, there is a problem that the tape attached to the wafer is prevented from being lifted from the wafer with the passage of time.

In the present invention for solving the above problems, an outer peripheral surplus region having an annular convex portion that is thicker than the device region and protrudes to the back surface side is formed around the device region in which a plurality of devices are formed on the front surface. In the tape sticking method of sticking the tape to the wafer, the surface to which the tape of the wafer is stuck is the back surface, and only the region corresponding to the outer peripheral surplus region in the back surface is irradiated with ultraviolet rays to remove organic substances. an ultraviolet irradiation step of removing the tape applying step of attaching the tape to the back surface of the wafer after performing said UV irradiation step, a tape applying method comprising a.

One of the factors that causes the tape attached to the wafer to rise from the wafer over time is that the tape is attached to the wafer with a minute amount of organic matter intervening between the tape and the wafer. The inventor of the present application has found that the adhesion between the tape and the wafer is weakened. Therefore, according to the present invention, a tape is attached to a wafer in which an outer peripheral surplus region having an annular convex portion that is thicker than the device region and protrudes to the back surface side is formed around the device region in which a plurality of devices are formed on the front surface. In the tape attaching method, the surface on which the wafer tape is attached is the back surface, and an ultraviolet irradiation step of irradiating only the region corresponding to the outer peripheral excess region in the back surface to remove organic substances is performed. By improving the adhesion between the tape and the wafer and then performing the tape attachment step of attaching the tape to the back surface of the wafer, it is possible to prevent the tape attached to the wafer from being lifted from the wafer over time. I did it. Further, if the entire back surface of the wafer is irradiated with ultraviolet rays in the ultraviolet irradiation step, the adhesion between the tape and the wafer is improved and the hydrophilicity of the entire back surface of the wafer is also increased. Then, when the wafer is divided into chips by a cutting device equipped with a rotating cutting blade, when the size of the divided chips becomes very small, etc., the hydrophilicity is improved between the back surface of the chips and the tape. Cutting water easily enters the surface, and the tip may float from the tape and cause tip jumping. Further, due to the increased hydrophilicity, cutting water containing contamination such as cutting chips wraps around the back surface of the chip during the cutting process, which may cause dirt to adhere to the back surface of the divided chip. Therefore, in the present invention, in the ultraviolet irradiation step, instead of irradiating the entire back surface with ultraviolet rays, only the region corresponding to the outer peripheral surplus region in the back surface of the wafer is irradiated with ultraviolet rays, so that the tape attached to the wafer takes time. It is possible to prevent the wafer from rising from the wafer over time, and the hydrophilicity of the region corresponding to the device region in the back surface of the wafer increases, which may cause chip skipping during cutting and to the back surface of the chip after division. It is possible to prevent the adhesion of dirt.

It is a perspective view which shows a part of the grinding apparatus which grinds a wafer, and an example of a wafer. It is sectional drawing which shows an example of the structure of a wafer after grinding. It is sectional drawing which shows the state which irradiates the back surface of a wafer with ultraviolet rays. It is sectional drawing which shows the state which the tape is attached to the wafer. It is a graph which shows the degree of expansion with the passage of time of the gap between a wafer and a tape. It is sectional drawing which shows the state which irradiates ultraviolet rays only to the region corresponding to the outer peripheral surplus region in the back surface of a wafer.

The wafer W shown in FIG. 1 is, for example, a semiconductor wafer having a circular plate shape in outer shape, and a device region Wa1 and an outer peripheral surplus region Wa2 surrounding the device region Wa1 are provided on the surface Wa thereof. The outer peripheral surplus region Wa2 is a region outside the virtual line L1 in the surface Wa of the wafer W in FIG. The device area Wa1 is divided into a plurality of rectangular areas by scheduled division lines S arranged in a grid pattern, and a device D such as an IC is formed in each rectangular area. The back surface Wb of the wafer W is a surface to be ground to be ground. When the wafer W is ground, the surface Wa of the wafer W is protected by the protective tape T1.

As shown in FIG. 1, for example, the grinding device 1 for grinding the wafer W includes a holding table 30 for holding the wafer W, a rough grinding unit 2A for roughly grinding the wafer W held on the holding table 30, and a holding table 30. It is provided with at least a finish grinding unit 2B for finish grinding the wafer W held in the.

The grinding device 1 includes a turntable 17, and for example, a plurality of holding tables 30 (two in the illustrated example) are arranged on the upper surface of the turntable 17 at equal intervals in the circumferential direction. A rotation axis (not shown) for rotating the turntable 17 is arranged at the center of the turntable 17, and the turntable 17 can rotate around the rotation axis. By rotating the turntable 17, each holding table 30 can be revolved and sequentially moved below the rough grinding unit 2A and below the finish grinding unit 2B.

Each holding table 30 arranged on the turntable 17 has, for example, a holding portion 300 having a circular outer shape and being made of a porous member or the like and sucking and holding the wafer W, and a frame body 301 for supporting the holding portion 300. And. The holding unit 300 communicates with a suction source (not shown), and the suction force generated by the suction source sucks is transmitted to the holding surface 300a, so that the holding table 30 sucks the wafer W on the holding surface 300a. Hold. Further, the holding table 30 can rotate around the axis in the vertical direction on the turntable 17.

The rough grinding unit 2A can move up and down in the Z-axis direction, and plays a role of rough grinding the wafer W to a finishing thickness. The rough grinding unit 2A includes a spindle 200 whose axial direction is the vertical direction (Z-axis direction), a housing 201 that rotatably supports the spindle 200, a motor 202 housed in the housing 201 and rotationally driving the spindle 200. A circular mount 203 connected to the lower end of the spindle 200 and a grinding wheel 204 detachably connected to the lower surface of the mount 203 are provided. The grinding wheel 204 includes a wheel base 204a and a plurality of roughly rectangular parallelepiped rough grinding wheels 204b arranged in an annular shape on the outer edge of the bottom surface of the wheel base 204a. The rough grinding wheel 204b is formed by fixing diamond abrasive grains or the like with, for example, a resin bond or a metal bond. The shape of the rough grinding wheel 204b may be an annular shape. The rough grinding wheel 204b is, for example, a grindstone used for rough grinding, and is a grindstone in which abrasive grains contained in the grindstone are relatively large. The coarse grinding wheels 204b arranged in an annular shape have, for example, such that the diameter of the outermost circumference thereof is larger than the radius of the device region Wa1 of the wafer W and smaller than the diameter of the device region Wa1 and the diameter of the innermost circumference thereof is the device. It is formed so as to be smaller than the radius of the region Wa1.

Inside the spindle 200, a flow path (not shown) that serves as a passage for grinding water is formed so as to penetrate in the axial direction (Z-axis direction) of the spindle 200. This flow path passes through the mount 203 and is opened at the bottom surface of the wheel base 204a so that the grinding water can be ejected toward the grinding wheel 204b.

The rough grinding unit 2A and the finish grinding unit 2B arranged side by side in the X-axis direction can move up and down in the Z-axis direction, and the wafer W thinned to about the finish thickness by rough grinding can be used with respect to the wafer W. Finish grinding that enhances the flatness of the surface to be ground in the back surface Wb of the wafer W can be performed. That is, the finish grinding unit 2B further grinds the wafer W ground by the rough grinding unit 2A with the finish grinding wheel 204c rotatably mounted. The abrasive grains contained in the finish grinding wheel 204c are abrasive grains having a smaller particle size than the abrasive grains contained in the rough grinding wheel 204b of the rough grinding unit 2A. The configuration of the finish grinding unit 2B other than the finish grinding wheel 204c is the same as the configuration of the rough grinding unit 2A.

Next, grinding of the back surface Wb of the wafer W using the grinding device 1 will be described. First, the wafer W to which the protective tape T1 is attached to the front surface Wa is placed on the holding surface 300a of the holding table 30 so that the center of the holding table 30 and the center of the wafer W are substantially aligned and the back surface Wb faces upward. It is placed in. Then, the suction force generated by the suction source (not shown) is transmitted to the holding surface 300a, so that the holding table 30 sucks and holds the wafer W on the holding surface 300a.

Then, for example, as shown in FIG. 1, the turntable 17 rotates clockwise when viewed from the + Z direction, so that the holding table 30 holding the wafer W revolves and moves to the bottom of the rough grinding unit 2A. The rough grinding wheel 204b of the rough grinding unit 2A and the wafer W held on the holding table 30 are aligned with each other. In this alignment, for example, the virtual line L1 and a part of the outermost periphery of the rotation trajectory of the rough grinding wheel 204b overlap on the inner peripheral edge of the outer peripheral excess region Wa2 of the wafer W, that is, the back surface Wb, and the rough grinding wheel 204b The rotation trajectory is performed so as to pass through the rotation center of the wafer W.

After the coarse grinding wheel 204b and the wafer W are aligned, the rough grinding wheel 204b rotates as the motor 202 rotationally drives the spindle 200 in the counterclockwise direction when viewed from the + Z direction, for example. Further, the rough grinding unit 2A is sent in the −Z direction, and as shown in FIG. 1, the rotating rough grinding wheel 204b comes into contact with the back surface Wb of the wafer W to grind the back surface Wb. During the grinding process, grinding water is supplied to the contact portion between the rough grinding wheel 204b and the wafer W through the flow path in the spindle 200 to cool the contact portion between the rough grinding wheel 204b and the back surface Wb of the wafer W. Wash. Further, during the grinding process, as the holding table 30 rotates counterclockwise when viewed from the + Z direction side, the wafer W held on the holding table 30 also rotates.

During the grinding process, for example, the rough grinding wheel 204b rotates so that the center of rotation of the wafer W is always located inside the outermost circumference of the rotating track of the rough grinding wheel 204b and outside the inner circumference of the rotating track. To do. Further, the outermost circumference of the rotary track of the grinding wheel 204b should not come into contact with the outer peripheral region of the back surface Wb corresponding to the outer peripheral surplus region Wa2 of the wafer W, that is, should not protrude to the outside larger than the virtual line L1. Machining control is performed. Therefore, the rough grinding wheel 204b grinds the central region of the back surface Wb corresponding to the device region Wa1 of the wafer W, and the central region of the back surface Wb corresponding to the device region Wa1 is ground into a circular concave shape. , Circular recess Wb1 is formed. Further, on the back surface Wb of the wafer W, an annular convex portion Wb2 corresponding to the outer peripheral surplus region Wa2 and surrounding the circular concave portion Wb1 is formed so as to project in the + Z direction.

After the wafer W is roughly ground by a predetermined grinding amount, the turntable 17 shown in FIG. 1 rotates clockwise when viewed from the + Z direction, so that the holding table 30 that holds the wafer W after rough grinding revolves. The holding table 30 moves to the lower side of the finish grinding unit 2B, and the finish grinding grind 204c of the finish grinding unit 2B and the wafer W held by the holding table 30 are aligned. For alignment, for example, the outermost circumference of the rotary track of the finish grinding wheel 204c is located slightly inside the inner wall of the annular convex portion Wb2 of the wafer W, and the rotary track of the finish grinding wheel 204c is the center of rotation of the wafer W. It is done to pass through. The reason why the finish grinding wheel 204c is positioned with respect to the wafer W in this way is that when the entire surface of the circular concave portion Wb1 is to be ground in the same region as the portion ground by the rough grinding, the inner wall of the annular convex portion Wb2 is finished and ground. Since the finish grinding wheel 204c is lowered and ground while the outer peripheral surface of the grindstone 204c is always in contact with each other, uneven wear occurs in which the finish grinding wheel 204c wears unevenly, which is later applied to a plurality of wafers W. This is because it becomes difficult to perform uniform grinding.

After the finish grinding wheel 204c and the wafer W are aligned, the finish grinding wheel 204c rotates, and the finish grinding unit 2B is sent in the −Z direction, and the rotating finish grinding wheel 204c is the wafer W. The finish grinding of the circular recess Wb1 is performed by abutting the circular recess Wb1 of the back surface Wb. During the finish grinding process, grinding water is supplied to the contact portion between the finish grinding wheel 204c and the back surface Wb of the wafer W to cool and clean the contact portion. Further, during the finish grinding process, the wafer W held on the holding table 30 also rotates as the holding table 30 rotates in the counterclockwise direction when viewed from the + Z direction side.

After improving the flatness of the circular recess Wb1 on the back surface Wb of the wafer W by finish grinding, the finish grinding unit 2B is moved in the + Z direction to separate it from the wafer W. In the wafer W after the finish grinding process shown in FIG. 2, for example, the width of the annular convex portion Wb2 is about 2 to 3 mm, and the thickness of the circular concave portion Wb1 is about 30 to 40 μm. Then, one annular step is formed in the outer peripheral region of the circular recess Wb1.

Next, the wafer W after the finish grinding process is in a state in which the protective tape T1 is peeled from the surface Wa by a tape peeling means composed of, for example, a clamp or the like. Then, for example, in order to cut the wafer W along the planned division line S of the front surface Wa of the wafer W by a cutting device equipped with a rotatable cutting blade and divide the wafer W into individual devices D, the back surface of the wafer W can be divided. A tape (for example, dicing tape) is attached to the Wb. Here, by implementing the tape attaching method according to the present invention, it is possible to prevent a situation in which the dicing tape attached to the wafer W is lifted from the wafer W with the passage of time.

(1) Ultraviolet Irradiation Step The grounded wafer W is transported to, for example, a tape mounter (not shown) for attaching a tape to the wafer W. During the grinding performed earlier, the back surface Wb of the wafer W was washed with washing water, but the grinding debris that could not be completely washed was attached to the back surface Wb of the wafer W as an organic substance. Further, in the wafer W transported to the tape mounter, in addition to the organic matter derived from the grinding chips adhering to the back surface Wb of the wafer W, the organic matter remaining in the flow path of the grinding water of each grinding unit is contained. During the grinding process, it may adhere to the back surface Wb of the wafer W, or organic substances such as sebum of the operator handling the wafer W may adhere to the back surface Wb of the wafer W.

Therefore, in the tape attaching method according to the present invention, for example, as shown in FIG. 3, the wafer W is set so that the back surface Wb, which is the surface to be ground, is on the lower side, and the holding surface of the holding pad 4 shown in FIG. It is sucked and held on 4a. The holding pad 4 that sucks and holds the weight W is, for example, irradiated with ultraviolet rays having a plurality of light sources 50 (for example, a low-pressure mercury UV lamp capable of generating ultraviolet rays having a wavelength of about 185 nm and a wavelength of about 254 nm). The wavelength W is conveyed above the device 5. That is, the wafer W is positioned by the holding pad 4 so that the back surface Wb of the wafer W faces the light source 50 that irradiates the ultraviolet rays in the + Z direction, and the ultraviolet rays of a predetermined wavelength (for example, 185 nm) emitted from the light source 50. However, the back surface Wb to which the tape of the wafer W is attached, that is, the entire surface of the circular concave portion Wb1 and the annular convex portion Wb2 is irradiated. After irradiating the back surface Wb of the waha W with ultraviolet rays having a wavelength of 185 nm for a certain period of time, the ultraviolet rays emitted from the light source 50 are switched to the ultraviolet rays having a wavelength of 254 nm, and the ultraviolet rays having a wavelength of 254 nm are radiated to the back surface Wb of the waha W for a certain period of time. The irradiation of ultraviolet rays having different wavelengths is performed, for example, a plurality of times. The ultraviolet irradiation device 5 may be arranged on the tape mounter, or may be independently installed on the moving path of the holding pad 4.

When ultraviolet rays having a wavelength of 185 nm are irradiated toward the back surface Wb of the wafer W, oxygen molecules in the air existing between the wafer W and the light source 50 absorb the ultraviolet rays to generate oxygen atoms in the ground state. The generated oxygen atoms combine with surrounding oxygen molecules to generate ozone. Further, ultraviolet rays having a wavelength of 185 nm are excited by breaking the interatomic bonds (for example, carbon-carbon bonds and carbon-hydrogen bonds) of organic substances adhering to the back surface Wb of the wafer W. Decomposes organic matter. Further, the generated ozone absorbs ultraviolet rays having a wavelength of 254 nm, so that active oxygen in an excited state is generated. Since the generated active oxygen and ozone have high oxidizing power, they combine with the decomposed organic substances such as carbon and hydrogen to become volatile substances such as carbon dioxide and water, and these volatile substances are the back surface Wb of the waiha W. Volatilized and removed from. Since the amount of active oxygen and ozone produced is much larger than the amount of organic matter adhering to the back surface Wb of the wafer W, the volatile substance formation reaction of the organic matter adhering to the back surface Wb of the wafer W is the wafer. It proceeds irreversibly to the extent that almost no organic matter remains on the back surface Wb of W. By decomposing and removing the organic matter adhering to the back surface Wb of the wafer W in this way, the back surface Wb of the wafer W is in a state of improved adhesion to the tape T2 shown in FIG.

(2) Tape sticking step The wafer W irradiated with ultraviolet rays is conveyed by the holding pad 4 and positioned on the tape T2 shown in FIG. 4 set on the tape mounter. The tape T2 is, for example, a circular tape having an outer diameter larger than the diameter of the wafer W, and includes a base material surface T2a made of a polymer resin and an adhesive surface T2b made of an adhesive glue layer. T2 is set in a state where the adhesive surface T2b side to be attached to the back surface Wb of the wafer W faces upward. Specific examples of the tape T2 are, for example, the model name D-184 tape manufactured by Lintec Corporation and the model name UC-334EP-85 tape manufactured by Furukawa Electric Co., Ltd. After the wafer W is positioned on the tape T2 so that the center of the wafer W and the center of the tape T2 substantially coincide with each other, the holding pad 4 is lowered and the back surface Wb of the wafer W is lowered with respect to the adhesive surface T2b of the tape T2. Is pressed from above, and the tape T2 is attached to the back surface Wb of the wafer W. Further, the press roller 6 shown in FIG. 4 may be reciprocated on the back surface Wb of the wafer W to which the tape T2 is attached to press the tape T2 more strongly against the back surface Wb of the wafer W. To attach the tape T2 to the back surface Wb of the wafer W, for example, the wafer W is conveyed onto the attachment table in the tape mounter by the holding pad 4, and the wafer W is attached to the back surface Wb of the wafer by a press roller or the like on the attachment table. It may be done by pressing the tape T2.

As shown in FIG. 4, when the tape T2 is not adhered to the portion where one step of the annular step in the outer peripheral region of the circular recess Wb1 of the wafer W is formed, and a predetermined gap V is formed. There is, and air has entered the gap V. Here, in the conventional tape sticking method, the tape is attached to the back surface of the wafer in a state where minute organic substances remain on the back surface Wb of the wafer W, that is, in a state where the adhesion between the tape and the back surface of the wafer is low. By sticking the tape, as time passes after the tape is stuck, the tape gradually peels off from the circular concave portion and the annular convex portion starting from the gap, and the gap widens, so that the tape becomes a wafer. There was a problem that it floated up from the back side of the.

On the other hand, in the tape sticking method according to the present invention, an ultraviolet irradiation step is performed to remove organic substances from the back surface Wb of the wafer W to improve the adhesion between the tape T2 and the back surface Wb of the wafer W, and then the back surface of the wafer W. By carrying out the tape sticking step of sticking the tape T2 to the Wb, the tape T2 gradually moves from the circular concave portion Wb1 and the annular convex portion Wb2 starting from the gap V even after a lapse of time has passed since the tape T2 was stuck. It is possible to prevent the tape T2 from rising from the back surface Wb of the wafer W by suppressing the tape T2 from peeling off and expanding the gap V.

From the graphs G1 to G4 shown in FIG. 5, the effect of the tape adhesive method according to the present invention can be confirmed. The graphs G1 to G4 shown in FIG. 5 are graphs showing the degree of expansion of the width of the gap V between the wafer W and the tape T2 with the passage of time, that is, the degree of expansion of the gap V shown in FIG. 4 in the X-axis direction. .. Graphs G1 and G2 are graphs when a tape with a model name D-184 manufactured by Lintec Corporation is used as the tape T2, and graphs G3 to G4 are graphs with a model name UC-334EP manufactured by Furukawa Electric Corporation as the tape T2. It is a graph when 85 tapes are used. Graphs G1 and G3 show the degree of spread of the gap V in the X-axis direction when the back surface Wb of the wafer W is not irradiated with ultraviolet rays by the transition of black dots. Graphs G2 and G4 show the degree of spread of the gap V in the X-axis direction when the back surface Wb of the wafer W is irradiated with ultraviolet rays by the transition of rhombus points. Then, from graphs G1 to G4, in any of the tapes of D-184 tape and UC-334EP-85 tape, the number of days when the wafer W was irradiated with ultraviolet rays was larger than that when the wafer W was not irradiated with ultraviolet rays. It can be judged that the degree of expansion of the gap V due to the progress of is small.

The tape sticking method according to the present invention is not limited to the above embodiment, and the configuration and shape of the grinding apparatus 1 and the type of wafer W shown in the attached drawings are also described. The present invention is not limited to the above, and can be appropriately changed within the range in which the effects of the present invention can be exhibited. For example, in the present embodiment, the wafer W to which the tape T2 is attached is a wafer in which the back surface side of the device region Wa1 is ground and the annular convex portion Wb2 is formed on the outer peripheral side thereof, but the wafer W is limited to this. Instead, the wafer W may be a wafer in which the entire back surface Wb is ground.

For example, in the ultraviolet irradiation step, as shown in FIG. 6, the ultraviolet rays may be irradiated only to the region Wb3 corresponding to the outer peripheral surplus region Wa2 in the back surface Wb to which the tape T2 of the wafer W is attached. Here, the region Wb3 corresponding to the outer peripheral surplus region Wa2 in the back surface Wb refers to the back surface side of the outer peripheral surplus region Wa2, and is on the inner peripheral side of the annular convex portion Wb2 in addition to the annular convex portion Wb2 and is the device region Wa1. A portion that does not reach the back side is included, and a side surface of the circular recess Wb1 is also included. In this case, the ultraviolet irradiation device 5 is equipped with a mask jig 55 capable of narrowing the irradiation range of the ultraviolet rays emitted from the light source 50. The mask jig 55 is, for example, a jig fixed to the upper surface 52a of a casing 52 made of a transparent member such as glass of the ultraviolet irradiation device 5 with a bolt or the like, and is an ultraviolet ray formed of a transparent member such as glass. A transmission plate 550, a plate-shaped fixing plate 551 made of stainless steel or aluminum and fixed to the ultraviolet transmission plate 550, and a mask plate 552 made of stainless steel or aluminum and fixed to the central region of the ultraviolet transmission plate 550. It has.

The fixing plate 551 includes a circular opening 551c whose central region is cut out in a circular shape. The ultraviolet transmissive plate 550 is gripped from all sides in the horizontal plane direction by, for example, a screw clamp (not shown) provided on the fixing plate 551, and is fixed to the fixing plate 551 so as to close the opening 551c. A mask plate 552 formed in a circular shape having a diameter smaller than that of the opening 551c is fixed to the upper surface of the ultraviolet transmission plate 550 with a bonding agent or the like, and the center of the mask plate 552 and the center of the opening 551c substantially coincide with each other. There is. An annular transmission portion 550a through which ultraviolet rays emitted from the light source 50 are transmitted is formed between the fixing plate 551 and the mask plate 552. The width K of the annular transmission portion 550a is about the same as the width of the region Wb3 corresponding to the outer peripheral surplus region Wa2 in the back surface Wb of the wafer W. In addition, for example, the width K of the annular transmission portion 550a may be changed to an arbitrary width by providing a plate member that can slide and move inward in the radial direction on the inner side wall portion of the fixing plate 551.

In the ultraviolet irradiation step, when ultraviolet rays are irradiated only to the region Wb3 corresponding to the outer peripheral surplus region Wa2 in the back surface Wb to which the tape T2 of the wafer W is attached, the wafer W is sucked and held on the holding surface 4a of the holding pad 4. The wafer W is positioned on the ultraviolet irradiation device 5 so that the annular transmission portion 550a of the mask jig 55 and the region Wb3 of the wafer W face each other in the Z-axis direction. Then, ultraviolet rays having a predetermined wavelength radiated from the light source 50 in the + Z direction pass through only the annular transmission portion 550a of the mask jig 55 and irradiate only the region Wb3.

Next, in the wafer W whose ultraviolet rays are applied only to the region Wb3, the tape T2 is attached to the back surface Wb of the wafer W in the tape attaching step, as shown in FIG. Then, for example, the wafer W is divided along the scheduled division line S shown in FIG. 1 by a cutting device including a rotating cutting blade, and is divided into individual chips including the device D. In the division of the wafer W by cutting, the cutting blade cuts from the front surface Wa side of the wafer W with respect to the wafer W whose back surface Wb side is sucked and held by the chuck table via the tape T2. Further, cutting water is supplied to the contact portion between the cutting blade and the wafer W.

Here, in the ultraviolet irradiation step, since the ultraviolet rays are irradiated only to the region Wb3 corresponding to the outer peripheral surplus region Wa2 in the back surface Wb to which the tape T2 of the wafer W is attached, the tape T2 attached to the wafer W is attached. Since it is possible to prevent the wafer from floating from the wafer W with the passage of time and the hydrophilicity of the region corresponding to the device region Wa1 in the back surface Wb of the wafer W has not increased, the region corresponding to the device region Wa1 in the back surface Wb Almost no cutting water enters between the tape T2, and as a result, it is possible to prevent the occurrence of chip skipping during cutting of the device region Wa1 which is the chip provided with the device D. Further, since the hydrophilicity of the region corresponding to the device region Wa1 in the back surface Wb of the wafer W, that is, the region to be the back surface of the chip after division is not increased, the cutting water containing cutting chips wraps around in this region. It is difficult and it is possible to prevent the adhesion of dirt on the back surface of the chip after division.

W: Wafer Wa: Wafer surface Wa1: Device area Wa2: Outer peripheral surplus area S: Scheduled division line D: Device Wb: Wafer back surface T1: Protective tape Wb1: Circular recess Wb2: Circular convex part 1: Grinding device 17: Turn Table 2A: Rough grinding unit 200: Spindle 201: Housing 202: Motor 203: Mount 204: Grinding wheel 204a: Wheel base 204b: Rough grinding wheel 2B: Finish grinding unit 204c: Finish grinding wheel 30: Holding table 300: Holding part 300a: Holding surface 301: Frame
4: Holding pad 4a: Holding surface of holding pad 5: Ultraviolet irradiation device 50: Light source 52: Casing
55: Mask jig 550: Ultraviolet ray transmitting plate 551: Fixed plate 552: Mask plate
T2: Tape 6: Press roller

Claims (1)

A tape attachment method in which a tape is attached to a wafer in which an outer peripheral surplus area having an annular convex portion that is thicker than the device area and protrudes to the back surface side is formed around a device area in which a plurality of devices are formed on the front surface. There,
The surface on which the wafer tape is attached is the back surface, and an ultraviolet irradiation step of irradiating only the region corresponding to the outer peripheral surplus region in the back surface to remove organic substances,
Tape applying method comprising a tape applying step, the of attaching the tape to the back surface of the wafer after performing said UV irradiation step.

Images