JP4728033B2 - Processing method of semiconductor wafer - Google Patents

Description

  The present invention relates to a processing method obtained by individually dividing a device such as a semiconductor chip from which an electrode protrudes from a semiconductor wafer.

  A semiconductor chip having an electronic circuit such as an IC or LSI formed on its surface is now indispensable for downsizing various electric / electronic devices. In such a device, a rectangular rectangular area is defined by cutting lines called streets on the surface of a disk-shaped semiconductor wafer, an electronic circuit is formed in these rectangular areas, and then the back side of the semiconductor wafer is formed. After being processed by grinding to a predetermined thickness, the semiconductor wafer is divided along the street. As means for dividing the semiconductor wafer in this way, there is a method of cutting the semiconductor wafer with a cutting blade as proposed in Patent Document 1 and the like.

  By the way, in recent years, in order to enable further miniaturization of electric and electronic equipment, bumps having a height of about 15 to 100 μm are formed as electrodes on the surface of the device, and the bumps are formed on the mounting substrate. A device called a flip chip, which is directly bonded to the formed electrode, has been developed and put into practical use. In addition, a technology for reducing the size by mounting or stacking a plurality of devices on a substrate called an interposer has been developed and put into practical use.

  In any of the above technologies, the substrates are bonded together by bonding via a plurality of bumps formed on the surface of the device. Must be uniform. Therefore, a processing apparatus for removing the tip of the bump and aligning the height as known in Patent Document 2 has been developed and provided.

  When manufacturing a device having such a bump, first the bump height is aligned as described above, and then the back side (the side without the bump) of the semiconductor wafer is ground to a predetermined thickness. , And cut along the street to get individual devices.

  The reason for aligning the bump height first is to hold the semiconductor wafer with the bump side surface aligned with the processing reference surface such as a chuck table, and to grind the exposed back surface to a predetermined thickness. If the thickness is not uniform, the semiconductor wafer cannot be ground to a uniform thickness, and stress may be concentrated on a part of the semiconductor wafer during the grinding.

JP 2001-85365 A JP 2004-319697 A

  When the semiconductor wafer with the bump height aligned is cut and divided into devices by the method described in the above-mentioned Patent Document 1, it has occurred that cutting waste adheres to the tip of the bump. If the cutting waste is not sufficiently removed from the bumps, there is a problem that when the device is mounted on a wiring board or the like, the bumps cannot be sufficiently crimped to the electrodes, resulting in a circuit that is easily disconnected. It has become a problem to be solved.

  Therefore, according to the present invention, when a device having electrodes protruding from the surface, such as the bumps, is divided from the semiconductor wafer, the processing for aligning the height of the electrodes and the grinding for reducing the thickness of the semiconductor wafer can be performed satisfactorily. At the same time, it is an object of the present invention to provide a processing method capable of obtaining a high-quality device that does not have a risk of disconnection in a mounted state, without causing cutting scraps to adhere to the electrodes.

The present invention relates to a semiconductor wafer processing method for individually obtaining a device from a semiconductor wafer in which a plurality of electrodes protrude and a plurality of devices partitioned by streets are formed on the surface. In the state where the filler is filled, and the electrode is embedded in the filler, the back side of the semiconductor wafer is held on the chuck table, and the surface of the semiconductor wafer is cut along the street to be obtained. A half-cut process for forming a dividing groove having a depth corresponding to the thickness of the device, and a plurality of electrodes together with the surface layer of the filler filled on the surface of the semiconductor wafer, with the back side of the semiconductor wafer held on the chuck table Electrode height aligning process of cutting the tip of the electrode to align the height of these electrodes, and a semiconductor in which the electrode height is aligned by the electrode height aligning process After cleaning the wafer, the surface of the semiconductor wafer is covered with a protective member, the protective member side is held on the chuck table, and the back surface side of the semiconductor wafer is ground until the dividing grooves are exposed, and the semiconductor wafer is And a back grinding process for dividing the device into individual devices.

  The present invention modifies the conventional procedure of aligning the electrode height, grinding the semiconductor wafer to a predetermined thickness, and finally dividing the semiconductor wafer to obtain a device. As a basic division, a division groove is formed along the street on the surface side of the semiconductor wafer, and then the height of the electrodes is made uniform. In this electrode height aligning step, the back surface of the semiconductor wafer on which the divided grooves are formed is held on the chuck table and the tip of the electrode is scraped off, so that the processing for aligning the electrode height is performed well.

  Then, the surface on which the electrodes having the same height are formed is covered with a protective member, the protective member side is held on the chuck table, and the back surface side of the semiconductor wafer is ground. When grinding on the back surface side is advanced, it eventually reaches the dividing groove, and the dividing groove appears. At this point, the semiconductor wafer is divided into individual devices, and individual devices are obtained by peeling them from the protective member. The thickness of each device has the thickness accurately because the depth of the dividing groove corresponds to the thickness of the device to be obtained. That is, in the final back grinding process, the semiconductor wafer is processed into a predetermined thickness and simultaneously divided into devices.

  In the half-cut process, the dividing grooves are formed by cutting, so that cutting waste generated at that time may adhere to the electrodes formed on the surface of the semiconductor wafer as in the past. Conventionally, the cutting waste has an adverse effect and causes a failure in mounting on a wiring board or the like. However, in the present invention, after the half-cut process, the cutting waste is removed in order to scrape off the tip of the electrode to make the height uniform. Therefore, the electrode can be sufficiently pressed against the electrode such as the wiring board, and therefore, the mounting can be performed satisfactorily and problems such as disconnection do not occur.

  In devices such as those obtained by the present invention, after being mounted on a wiring board or the like, it is possible to prevent dust from entering between the electrodes of the device, or to reduce stress concentration on the electrodes when the electrodes are crimped Thus, filling the resin between the electrodes has been conventionally performed. However, in recent years, with the miniaturization of devices, the gap between the electrodes has become extremely narrow, and it has become difficult to sufficiently fill the resin.

Therefore, in the present invention, the surface of the semiconductor wafer is filled with a filler such as a resin in advance, and a half-cut process is performed in a state where the electrode is embedded in the filler. remove the surface layer. Thus, if the filler is filled in advance between the electrodes, it is not necessary to fill the filler after mounting, and the productivity is improved.

  According to the present invention, a dividing groove having a depth corresponding to the thickness of the device to be obtained is formed along the street on the surface of the semiconductor wafer, and then the height of the electrodes is made uniform. Since the semiconductor wafer is divided into individual devices by grinding the back side of the wafer until the dividing groove is exposed, the processing to align the height of the electrodes and the grinding to reduce the thickness of the semiconductor wafer can be performed well. As a result, there is no sticking of cutting scraps to the electrodes, and as a result, it is possible to obtain a high-quality device that is not likely to be disconnected in the mounted state.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1A shows a disk-shaped semiconductor wafer to be processed in this embodiment. A plurality of devices (semiconductor chips) 2 are formed on the surface of the semiconductor wafer 1. These devices 2 are configured by forming an electronic circuit in a rectangular region partitioned in a grid by streets 3 that are cutting lines.

  Each device 2 is formed with a plurality of bumps (electrodes) 4 as shown in FIG. The bump 4 is bonded to the electrode of the electronic circuit formed on the device 2 and protrudes from the surface of the device 2. These bumps 4 are formed by, for example, a well-known stud bump forming method, and the heights are often uneven.

  In the present embodiment, a “half-cut process” in which a dividing groove for dividing the device 2 is formed on the surface of the semiconductor wafer 1 by cutting, and the bump 4 is cut to make the bumps 4 have the same height. A plurality of devices 2 are divided from one semiconductor wafer 1 by performing a “leveling process” and a “back grinding process” in which the back side of the semiconductor wafer 1 is ground and simultaneously divided into devices 2 in this order. The processing method obtained. In the following, these steps will be described together with the apparatus used for the steps.

[1] Half-cut process (a) Dividing apparatus FIG. 2 shows a dividing apparatus used in the half-cut process.
The dividing apparatus 10 includes a base 100. On the base 100, a chuck table mechanism 120 that holds the semiconductor wafer 1 horizontally and moves it in the cutting feed direction (X direction in FIG. 2), and a semiconductor A cutting unit 140 that cuts the surface of the wafer 1 to form divided grooves, and a cutting unit support mechanism 160 that supports the cutting unit 140 and moves it in the indexing direction (Y direction in FIG. 2) are provided. . The cutting unit 140 is attached to the cutting unit support mechanism 160 so as to be movable in the cutting direction (Z direction in FIG. 2).

  The chuck table mechanism 120 is disposed on one end side in the Y direction on the base 100, and is attached to the guide rail 121 slidably on a pair of guide rails 121 extending in the X direction fixed to the base 100. A movable plate 122, a stage 124 supported on the movable plate 122 via a cylindrical post 123, a disk-shaped chuck table 125 rotatably mounted on the stage 124, and a movable plate 122. And a slide mechanism 130 that moves the guide along the guide rail 121.

  The chuck table 125 has a horizontal upper surface and is rotated clockwise or counterclockwise by a rotation driving mechanism (not shown) housed in the post with the Z direction as a rotation axis.

  In this case, the chuck system of the chuck table 125 is a well-known vacuum chuck. The chuck table 125 is formed with suction holes leading to the front and back surfaces, and an air suction port of a vacuum device (not shown) is connected to the back surface side. ing. When the vacuum device is operated, the semiconductor wafer 1 is attracted and held on the chuck table 125.

  The slide mechanism 130 includes a screw rod 131 disposed between the base 100 and the moving plate 122 and extending in the X direction, and a pulse motor 132 that rotationally drives the screw rod 131. The screw rod 131 is threadedly engaged with a bracket (not shown) formed to protrude from the lower surface of the moving plate 122, and is rotatably supported in an axially immovable state. According to the slide mechanism 130, when the screw rod 131 is rotated by the pulse motor 132, the moving plate 122 is moved along the guide rail 121 in the X direction corresponding to the rotation direction.

  The cutting unit support mechanism 160 includes a pair of guide rails 161 extending in the Y direction and arranged on the base 100 so as to form a T shape together with the guide rails 121 of the chuck table mechanism 120, and these guide rails. A movable table 162 slidably mounted on 161 and a slide mechanism 170 for moving the movable table 162 along the guide rail are provided.

  The movable table 162 includes a horizontal plate portion 163 and one end portion in the X direction of the horizontal plate portion 163 (in this case, the direction of the cutting unit 140 is observed along the Y direction from the end portion of the base 100 on the chuck table mechanism 120 side). 2 is an L-shaped base having a vertical plate portion 164 rising from the right end portion in the direction of arrow F in FIG. 2, and the lower surface of the horizontal plate portion 163 is slidably attached to the guide rail 161. .

  The slide mechanism 170 has the same configuration as that of the slide mechanism 130 of the chuck table mechanism 120, and includes a screw rod 171 disposed between the base 100 and the horizontal plate portion 163 and extending in the Y direction, and the screw rod 171. And a pulse motor 172 that rotates. The screw rod 171 is threadedly engaged with a bracket (not shown) protruding from the lower surface of the horizontal plate portion 163, and is rotatably supported in a state in which it cannot move in the axial direction. According to this slide mechanism 130, when the screw rod 171 is rotated by the pulse motor 172, the moving table 162 is moved along the guide rail 161 in the Y direction corresponding to the rotation direction.

  The cutting unit 140 reads a cylindrical housing 141 extending in the Y direction, a disk-shaped cutting blade 142 attached to the tip of the housing 141 on the chuck table mechanism 120 side, and a cutting line cut by the cutting blade 142. Alignment means 150. The cutting unit 140 is attached to the left surface of the vertical plate portion 164 of the movable table 162 as viewed in the direction of arrow F via a housing holder 165.

  The housing holder 165 is slidably attached to a vertically extending guide rail 166 formed on the left side surface of the vertical plate portion 164, and a pulse motor 180 fixed on the vertical plate portion 164 is a driving source. Is lifted and lowered along the guide rail 166 by the lifting mechanism. The housing 141 is passed through and fixed to the housing holder 165, so that the cutting unit 140 can be moved up and down together with the housing holder 165.

  The cutting blade 142 attached to the front end of the housing 141 is a so-called hub blade fixed to the periphery of the umbrella-shaped hub 143 as shown in FIG. The hub 143 is fixed to a tip end of a spindle 144 that is rotationally driven by a motor (not shown) accommodated in the housing 141 by a clamping metal member 145. The axial direction of the spindle 144 is parallel to the Y direction, and a dividing groove, which will be described later, is formed on the surface of the semiconductor wafer 1 at the exposed lower portion of the cutting blade 142 that rotates integrally with the spindle 144.

  The alignment unit 150 includes a microscope, a CCD camera, and the like, and has an imaging unit 151 that images a subject at the tip. The alignment unit 150 is attached to the tip of the housing 141 such that the imaging unit 151 is adjacent to the cutting feed direction (Y direction) of the cutting blade 142.

(B) Half-Cut of Semiconductor Wafer Next, a half-cut process for forming a division groove on the surface of the semiconductor wafer 1 by the division apparatus 10 will be described.

  First, as shown in FIG. 4A, the surface of the semiconductor wafer 1 is filled with a transparent resin film (filler) 5 thicker than the bump 4, and the bump 4 is embedded in the resin film 5. It is assumed that The resin film 5 is made of, for example, polyimide, epoxy, or the like.

  Next, a dividing groove is formed by the dividing device 10. The dividing apparatus 10 has a control unit that controls various operations.

  First, the operator places the semiconductor wafer 1 on the chuck table 125 of the chuck table mechanism 120 with the surface on which the plurality of devices 2 having the bumps 4 are formed facing upward, and operates the vacuum device of the chuck table mechanism 120. . As a result, the semiconductor wafer 1 is attracted and held on the chuck table 125.

  Next, the chuck table 125 is moved in the Y direction together with the moving table 122 by the slide mechanism 130, and the semiconductor wafer 1 is positioned directly below the imaging unit 151 of the alignment means 150 previously arranged on the moving line of the chuck table 125. It is done.

  Then, the street 3 on the surface of the semiconductor wafer 1 is photographed by the alignment means 150, and the chuck table 125 is rotated by the control means based on the image, and the street 3 extending in one direction becomes parallel to the Y direction (that is, The semiconductor wafer 1 is aligned with the cutting blade 142 so that the street 3 orthogonal to the street 3 extends in the X direction.

  Further, the control unit performs image processing on the image picked up by the alignment unit 150, and determines and stores a cutting operation pattern based on the processed image. The cutting operation pattern is such that the cutting blade 142 is moved by moving the cutting unit 140 in the Z direction so as to form divided grooves having a depth corresponding to the thickness of the device 2 to be obtained on all the grid-like streets 3. This is a combination of cutting feed, cutting feed of the cutting blade 142 by movement of the chuck table 125 in the X direction, and indexing of the cutting blade 142 by movement of the cutting unit 140 in the Y direction. Here, the cutting depth of the cutting blade 142 is set to a depth corresponding to the thickness of the device 2 to be obtained as described above.

  As shown in FIG. 5 (b), the lifting mechanism using the slide mechanisms 130 and 170 and the pulse motor 180 as a drive source is operated by the control means according to the stored cutting operation pattern. Thus, the division grooves 6 along the streets 3 extending in a lattice shape are formed on the surface of the semiconductor wafer 1.

  FIG. 5 is a cross-sectional view showing, in order from (a) to (f), the state of processing performed on the semiconductor wafer 1 until the semiconductor wafer 1 is processed to obtain individual devices 2 according to the present embodiment. a) is the semiconductor wafer 1 shown in FIG. 1 before processing. In addition, in FIG. 5, illustration of the said resin film 5 is omitted.

  The dividing groove 6 is formed by first repeating the movement of the chuck table 125 in the Y direction and the movement of the moving table 162 in the X direction alternately to form the dividing groove 6 along the street 3 extending in the Y direction. Is done. Next, the chuck table 125 is rotated by 90 °, and again, the movement of the chuck table 125 in the Y direction and the movement of the cutting unit support mechanism 160 in the X direction are repeated alternately. A dividing groove 6 is formed along the street 3 orthogonal to the street 3 on which the 6 is formed.

  FIG. 6 shows the semiconductor wafer 1 having the dividing grooves 6 formed on the surface along all the streets 3 by the above method, and this semiconductor wafer 1 is sent to the next bump height alignment step.

[2] Bump Height Alignment Step (a) Bump Processing Device FIG. 7 shows a bump processing device used in the bump height alignment step.
The bump processing apparatus 20 applies a process to the semiconductor wafer 1 by cutting off the tip of the bump 4 to make the height uniform.

  The bump processing apparatus 20 includes a base 210 on which various mechanisms are mounted. The base 210 is installed in a horizontally long state and has a rectangular parallelepiped table 211 which is the main body of the base 210, and a longitudinal end of the table 211 (the end on the back side in FIG. 7). A wall portion 212 extending in the width direction and vertically upward. In FIG. 7, the longitudinal direction, the width direction, and the vertical direction of the base 210 are shown as a Y direction, an X direction, and a Z direction, respectively.

On the table 211 of the base 210, the wall 212 side from the substantially middle portion in the longitudinal direction is the processing area 211A, and the opposite side is the semiconductor wafer 1 before processing (the divided grooves 6 are formed in the processing area 211A, and the bumps are formed. 4 is a supply / recovery area 211B for supplying semiconductor wafers 1) having irregular heights and for recovering the processed semiconductor wafers 1).
Hereinafter, various mechanisms will be described separately for those provided in the processing area 211A and those provided in the supply / recovery area 211B.

As shown in FIG. 7, a rectangular recess 213 is formed in the machining area 211A, and the rectangular stage 214 is movable in the Y direction in the recess 213. Is provided. The stage 214 is slidably attached to a guide rail that extends in the Y direction and is arranged in the table 211, and is reciprocated in the same direction by an appropriate drive mechanism (not shown).

  One ends of bellows 215 and 216 are attached to both ends of the stage 214 in the moving direction, respectively, and the other ends of these bellows 215 and 216 are the inner surface of the wall portion 212 and a recess 213 facing the wall portion 212. Are attached to the inner wall surface of each. These bellows 215 and 216 cover a slit (not shown) formed on the bottom surface of the recess 213 in order to connect the stage 214 to the guide rail, and prevent cutting chips and the like from falling into the table 211. Thus, the stage 214 expands and contracts with the movement of the stage 214 and does not hinder the movement.

  On the stage 214, a disk-shaped chuck table 217 having a rotation axis in the Z direction and a horizontal upper surface is rotatably provided. The semiconductor wafer 1 is placed on the chuck table 217 with the surface on which the bumps 4 are formed facing upward. The chuck table 217 is rotated clockwise or counterclockwise by a rotation driving mechanism (not shown) provided in the stage 214. Since the cutting unit 220 described later in this embodiment is a type that rotates a cutting tool 226 that is a cutting tool, the chuck table 217 that holds the semiconductor wafer 1 may be fixed without being freely rotatable. preferable.

  The chuck table 217 is also of a vacuum chuck type, similar to the chuck table 125, so that when a vacuum device (not shown) accommodated in the table 211 is operated, the semiconductor wafer 1 is attracted and held on the chuck table 217. It has become.

  When the chuck table 217 moves to the wall 212 side, the chuck table 217 is positioned at the machining position, and the cutting unit 220 is disposed above the machining position. The cutting unit 220 is supported by the wall portion 212 via a feed mechanism 230 so as to be movable up and down in the Z direction.

  The feed mechanism 230 includes a pair of guide rails 231 that are fixed to the inner surface of the wall portion 212 that is a vertical surface and extend in the Z direction, and a movable plate 232 that is slidably attached to the guide rails 231. An elevating mechanism 233 that elevates and lowers the moving plate 232 along the guide rail 231 is provided.

  The elevating mechanism 233 is arranged in the space between the moving plate 232 and the wall portion 212 with the axial direction parallel to the Z direction, and the upper end portion and the lower end portion are bearings 234 and 235 provided on the wall portion 212, respectively. And a pulse motor 237 that rotationally drives the screw rod 236. The screw rod 236 is screwed into and penetrates a bracket (not shown) formed on the back surface of the moving plate 232. Thus, the moving plate 232 moves downward (feed direction) when the pulse motor 237 rotates forward and the screw rod 236 rotates in one direction, and the pulse motor 237 reverses and the screw rod 236 moves in the reverse direction. When it is rotated, it moves upward (withdrawal direction).

  The cutting unit 220 includes a block 221 fixed to the front surface of the moving plate 232 facing the table 211, and a cylinder that is passed through the block 221 with the axial direction along the Z direction and fixed to the block 221. A housing 222, a rotating shaft 223 concentrically and rotatably supported in the housing 222, a servo motor 224 that rotationally drives the rotating shaft 223, and a rotating shaft 223 that protrudes downward from the housing 222. A disk-shaped bite mount 225 concentrically fixed to the lower end and a bite 226 detachably attached to the bite mount 225 are provided. In this case, the rotary shaft 223 and the bite mount 225 are rotated in the direction of the arrow in FIG. 7 (described on the upper surface of the bite mount 225) by the servo motor 224.

  As shown in FIG. 8, the cutting tool 226 has a blade 228 made of diamond or the like fixed to the tip of the shank 227, and the blade 228 cuts the tip of the bump 4. The cutting tool 226 has the blade part 228 disposed below, and the shank 227 is mounted on the cutting tool with the cutting direction of the cutting part 228 (the arrow direction in FIG. 8A) directed to the rotation direction of the cutting tool mount 225. It is inserted from below into a mounting hole 225a formed in 225. The inserted state is fixed by a bolt 229 screwed from the outer peripheral surface of the bite mount 225 toward the mounting hole 225a. Accordingly, the cutting tool 226 is fixed in a state of protruding downward from the outer peripheral portion of the cutting tool mount 225.

  As shown in FIG. 9, the outer diameter of the bite mount 225 is about 1.5 times the diameter of the semiconductor wafer 1, but the dimensions are not limited to this. However, the rotation trajectory of the cutting tool 226 based on the mounting position on the cutting tool mount 225 is set to a size that allows the entire surface of the semiconductor wafer 1 to be processed. Further, the chuck table 217 and the cutting unit 220 are arranged such that a line connecting the center of the semiconductor wafer 1 concentrically held on the chuck table 217 and the rotation center of the bite mount 225 is in a state along the Y direction. Is positioned.

-Mechanism of supply / recovery area 211B As shown in FIG. 7, a rectangular recess 218 is formed in the supply / recovery area 211B set on the table 211 of the base 210, and this recess At the bottom of 218, a transfer mechanism 260 is installed in which a fork 260b is attached to the tip of a two-joint horizontal swivel arm 260a that can be raised and lowered.

  Then, on the table 211 around the recess 218, a suction plate 263 b is attached to the tip of the cassette 261, the alignment table 262, and the horizontal swing arm 263 a of the first node in a counterclockwise direction as viewed from above. The recovery arm 264 having the same structure as the supply arm 263 and the supply arm 263, the horizontal swivel arm 264a and the suction plate 264b, the spinner type cleaning device 265, and the cassette 266 are arranged.

  The cassette 261, the alignment table 262, and the supply arm 263 are means for supplying the semiconductor wafer 1 to the chuck table 217, and the recovery arm 264, the cleaning device 265, and the cassette 266 are used to move the processed semiconductor wafer 1 from the chuck table 217. It is a means to collect. Although the two cassettes 261 and 266 have the same structure, they are referred to as a supply cassette 261 and a recovery cassette 266 depending on the application. These cassettes 261 and 266 are for accommodating and carrying a plurality of semiconductor wafers 1 and are set at predetermined positions on the table 211.

  In the supply cassette 261, a plurality of semiconductor wafers 1 whose bumps 4 are to be processed by the bump processing apparatus 20 are accommodated in a stacked state. The transfer mechanism 260 takes out one semiconductor wafer 1 from the supply cassette 261 by raising / lowering and turning the arm 260a and gripping the fork 260b, and further removes the semiconductor wafer 1 from the surface on which the bumps 4 are formed. It has a function of being placed on the alignment table 262 in a state of facing upward.

  The semiconductor wafer 1 placed on the alignment table 262 is placed in a state determined at a certain position. The supply arm 263 sucks the semiconductor wafer 1 placed on the alignment table 262 onto the suction plate 263b, turns the arm 263a, and places the semiconductor wafer 1 on the chuck table 217, and then performs the suction operation. Is stopped, the semiconductor wafer 1 is placed on the chuck table 217. By placing the semiconductor wafer 1 positioned by the alignment table 262 on the chuck table 217 at the supply / recovery position, the semiconductor wafer 1 and the chuck table 217 are concentric.

  The recovery arm 264 sucks the semiconductor wafer 1 on the chuck table 217 on which the bumps 4 are processed by the cutting unit 220 to the suction plate 264b, and rotates the arm 264a to transfer the semiconductor wafer 1 into the cleaning device 265. It has a function. The cleaning device 265 has a function of rotating and removing the semiconductor wafer 1 after the semiconductor wafer 1 is cleaned to remove moisture. The semiconductor wafer 1 cleaned by the cleaning device 265 is transferred and accommodated in the recovery cassette 266 by the transfer mechanism 260.

  A chuck table cleaning nozzle 267 for cleaning the chuck table 217 by spraying high-pressure air onto the chuck table 217 is disposed between the supply arm 263 and the recovery arm 264. As described above, the semiconductor wafer 1 is placed on the chuck table 217 by the supply arm 263, and when the semiconductor wafer 1 on the chuck table 217 is recovered by the recovery arm 264, that is, the semiconductor wafer 1 with respect to the chuck table 217. When 1 is attached or detached, the stage 214 is moved to the supply / recovery area 211B and stopped at the supply / recovery position. The supply / recovery position is a position along the Z direction where a line connecting the center of the semiconductor wafer 1 sucked by the suction plates 263b and 264b of the arms 263 and 264 and the center of the chuck table 217 is provided.

  The processing position of the semiconductor wafer 1 by the cutting unit 220 is a range moved by a predetermined distance from the supply / recovery position to the wall 212 side. The semiconductor wafer 1 on the chuck table 217 is moved to the processing position by moving the stage 214. And the supply / recovery position. The chuck table 217 is cleaned by the chuck table cleaning nozzle 267 at the supply / recovery position.

(B) Bump Height Alignment Next, the operation of aligning the bumps 4 protruding on the surface of the semiconductor wafer 1 that has undergone the half-cut process by the bump processing apparatus 20 will be described.

  The operator sets a supply cassette 261 containing a plurality of semiconductor wafers 1 to be machined by cutting the bumps 4 and an empty collection cassette 266 at predetermined positions in the supply / collection area 211B.

  Subsequently, one semiconductor wafer 1 is taken out from the supply cassette 261 by the transfer mechanism 260, and the semiconductor wafer 1 is positioned in a state where the surface on which the bumps 4 are formed by the transfer mechanism 260 faces upward. It is placed on the alignment table 262.

  Next, the semiconductor wafer 1 placed on the alignment table 262 is placed concentrically by the supply arm 263 on the chuck table 217 that has been previously stopped at the supply / recovery position with the surface facing up. . The semiconductor wafer 1 is sucked and held on the chuck table 217 by a vacuum device.

  Next, the height of the cutting unit 220 is adjusted by the feed mechanism 30 so that the cutting tool 226 can cut the bump 4 to a predetermined height, and the cutting tool mount 225 is rotated by the servo motor 224. From this state, the stage 214 is moved to the cutting unit 220 side, and the semiconductor wafer 1 held on the chuck table 217 in a fixed state is sent to a processing position below the cutting unit 220 at a predetermined speed. Go. As a result, as shown in FIG. 5C, the tips of the bumps 4 on the surface of the semiconductor wafer 1 are scraped off by the blade portion 228 of the cutting tool 226. Further, as shown in FIG. 4B, the surface layer of the resin film 5 previously filled on the surface of the semiconductor wafer 1 is removed together with the tips of the bumps 4.

  As shown in FIG. 9, by moving the chuck table 217 until the semiconductor wafer 1 is covered with the bite mount 225, the tips of all the bumps 4 are scraped and the heights are made uniform. The saw mark, which is a cutting pattern of the cutting tool 226, is processed by feeding the non-rotating semiconductor wafer 1 with the chuck table 217 fixed to the rotating cutting tool 226 to process the entire surface of the cutting tool 226. It becomes like 1. After processing the entire surface of the semiconductor wafer 1 as described above, the cutting unit 220 is raised to stop the rotation of the bite mount 225 and stop the cutting process.

  Next, the operation of recovering the processed semiconductor wafer 1 with the bumps 4 of the same height will be described. First, the stage 214 is moved to the supply / recovery position, the operation of the vacuum device is stopped, and the chuck table is stopped. The holding state of the semiconductor wafer 1 on 217 is released. Next, the semiconductor wafer 1 is transferred into the cleaning device 265 by the recovery arm 264. Here, the semiconductor wafer 1 is cleaned and then rotated to remove moisture.

  Next, the semiconductor wafer 1 is transferred and accommodated in the collection cassette 266 by the transfer mechanism 260. In addition, after the semiconductor wafer 1 is removed from the chuck table 217 by the recovery arm 264, high-pressure air flows from the chuck table cleaning nozzle 267 toward the chuck table 217 on the stage 214 that is stopped at the supply / recovery position. The chuck table 217 is cleaned by spraying.

  The above is the cycle in which the tips of the bumps 4 are cut and aligned to the height of one semiconductor wafer 1 and then washed and recovered. The semiconductor wafer 1 in which the bumps 4 have the same height is sent to the next back grinding process.

[3] Back grinding step (a) Grinding device FIG. 10 shows a grinding device used in the back grinding step.
The grinding apparatus 30 includes a base 310 on which various mechanisms are mounted. The base 310 is installed in a horizontally long state and is a rectangular parallelepiped table 311 which forms the main body of the base 310, and the width of the table 311 from one end in the longitudinal direction of the table 311 (the end on the back side in FIG. 10). And a wall portion 312 extending vertically upward. In FIG. 10, the longitudinal direction, the width direction, and the vertical direction of the base 310 are indicated by the Y direction, the X direction, and the Z direction, respectively.

  A recess 313 is formed on the upper surface of the table 311, and a stage 314 and bellows 315 and 316 similar to those provided in the bump processing apparatus 20 are provided in the recess 313. The stage 314 reciprocates in the Y direction by a driving mechanism (not shown), and the bellows 315 and 316 expand and contract with the movement.

  On the stage 314, a chuck table 317 employing a vacuum chuck system similar to the chuck tables 125 and 217 is rotatably provided. The chuck table 317 is moved together with the stage 314 toward the wall 312 and positioned at the machining position. A grinding unit 320 is disposed above the processing position.

  The grinding unit 320 is supported via the feed mechanism 330 so as to be movable up and down in the Z direction with respect to the wall 312. The feed mechanism 330 has the same configuration as the feed mechanism 230 included in the bump processing apparatus 20, and includes a pair of guide rails 331, a moving plate 332 that slides along the guide rails 331, and guides the moving plate 332. An elevating mechanism 333 that elevates and lowers along the rail 331 is provided.

  The grinding unit 320 has the same configuration as the cutting unit 220 of the bump processing apparatus 20, and includes a block 321 fixed to the front surface of the moving plate 332, a cylindrical housing 322 fixed to the block 321, A rotating shaft 323 supported in the housing 322 and a servo motor 324 that rotationally drives the rotating shaft 323 are provided. A disc-shaped wheel mount 325 is fixed to the lower end of the rotating shaft 323, and a grinding wheel 326 is detachably attached to the lower surface of the wheel mount 325.

  As shown in FIG. 11, the grinding wheel 326 has a large number of chip-like grindstones 328 fixed to the lower surface of a wheel ring 327 having the same diameter as the wheel mount 325. The grindstone 328 is made of, for example, resin bond.

  The grinding wheel 326 is detachably screwed to the lower surface of the wheel mount 325 using a plurality of bolt holes 327a formed on the upper surface of the wheel ring 327 (the surface to which the grindstone 328 is not fixed). In this case, the outer diameter of the grinding wheel 326 is approximately the same as the diameter of the semiconductor wafer 1 or about 1.5 times, but the dimensions are not limited thereto. Further, the positional relationship between the grinding unit 320 and the chuck table 317 is such that both rotation centers are aligned in the Y direction.

(B) Grinding / dividing the back surface of the semiconductor wafer In the back surface grinding step, the back surface side of the semiconductor wafer 1 that has undergone the bump height aligning step is ground by the grinding device 30. Prior to that, FIG. 12 (a) and FIG. As shown in FIG. 5D, a protective seal (protective member) 7 is attached to the entire surface of the semiconductor wafer 1. The protective seal 7 prevents grinding scraps from adhering to the bumps 4 and protects the bumps 4 and the circuit.

  When the surface of the semiconductor wafer 1 is thus covered with the protective seal 7, the semiconductor wafer 1 is processed by the grinding device 30 as follows.

  First, the operator places the semiconductor wafer 1 on the chuck table 317 with the back surface not covered with the protective seal 7 facing upward, operates the vacuum device, and holds the semiconductor wafer 1 on the chuck table 317. Then, the semiconductor wafer 1 is moved to a processing position below the grinding unit 320 by moving the stage 314. In this case, the stage 314 is moved to a position where at least the radius on the wall 312 side of the semiconductor wafer 1 covers the grinding wheel 326.

  From this state, the chuck table 317 is rotated to rotate the semiconductor wafer 1, and at the same time, the grinding wheel 326 of the grinding unit 320 is rotated by the servo motor 324 and the grinding unit 320 is moved at a predetermined speed by the feed mechanism 330. Lower slowly. The rotation direction of the chuck table 317 may be the same direction as that of the grinding wheel 326 or may be the opposite direction.

  As the grinding unit 320 descends, the grindstone 328 of the rotating grinding wheel 326 contacts the back surface of the rotating semiconductor wafer 1 and presses the back surface with a predetermined load. Thereby, the back surface side of the semiconductor wafer 1 is ground flat.

  As the grinding of the back surface side of the semiconductor wafer 1 proceeds, the grindstone 328 eventually reaches the divided grooves 6 and the divided grooves 6 are exposed as shown in FIGS. 12B and 5E. At this point, the semiconductor wafer 1 is divided into individual devices 2 but is not yet separated because it is connected to each other by the protective seal 7.

  When the dividing groove 6 is exposed, grinding is stopped, the semiconductor wafer 1 is removed from the chuck table 317, and the divided device 2 is peeled off from the protective seal 7. As a result, individual devices 2 are obtained as shown in FIG. 5 (f), and these devices 2 are mounted on a wiring board or the like by pressing the bumps 4 on the electrodes.

  In the processing method for obtaining the device 2 from the semiconductor wafer 1 as described above, first, the dividing groove 6 is formed (half cut) on the semiconductor wafer 1, and then the bumps 4 are made to have the same height, and then divided. The back side of the semiconductor wafer 1 is ground until the groove 6 is exposed, and the devices 2 having a predetermined thickness are individually divided in the final back grinding process. The thickness of the obtained device 2 has the thickness accurately because the depth of the dividing groove 6 corresponds to the thickness of the device 2 to be obtained.

  When the dividing groove 6 is cut and formed in the half-cut process, cutting waste may adhere to the bump 4, but the cutting waste is removed by scraping the tip of the bump 4 in the next height alignment process. . Therefore, the bumps 4 can be sufficiently bonded to the electrodes such as the wiring board, and thus the mounting can be performed satisfactorily, so that problems such as disconnection do not occur.

  Further, even after being divided into the devices 2, the resin film 5 filled first is held in a state of remaining between the bumps 4, so that it is not necessary to fill the resin between the bumps 4 after mounting. Is improved. Whether or not the resin film 5 is filled on the surface of the semiconductor wafer 1 is selected as necessary.

1A is an overall perspective view of a semiconductor wafer to be processed in one embodiment of the present invention, and FIG. 1B is a plan view of a semiconductor chip formed on the semiconductor wafer. It is a whole perspective view of the dividing device used at the half cut process of one embodiment. It is a sectional side view which shows the attachment structure of the cutting blade which a dividing device comprises. (A) is sectional drawing which shows the state which filled the resin film on the surface of the semiconductor wafer before using for a half cut process, (b) is sectional drawing of the semiconductor wafer after bump height alignment process. It is sectional drawing which shows the processing state of the semiconductor wafer processed by the processing method of one Embodiment in order of (a)-(f). It is a perspective view of the surface side of the semiconductor wafer after a half cut process. It is a whole perspective view of the bump processing apparatus used at the bump height alignment process of one Embodiment. It is the (a) side view of the cutting tool of the cutting unit which a bump processing apparatus comprises, (b) The front view. It is a top view which shows the positional relationship of the bite mount of the cutting unit and the semiconductor wafer hold | maintained at a chuck | zipper table, and the saw mark of a semiconductor wafer. 1 is an overall perspective view of a grinding device used in a back grinding process of one embodiment. It is a perspective view of the grinding wheel of the grinding device. (A) is the perspective view of the back surface side of the semiconductor wafer by which the protective seal was affixed on the surface prior to the back surface grinding process, (b) is the perspective view of the surface side of the semiconductor wafer after the back surface grinding process.

Explanation of symbols

1. Semiconductor wafer 2. Device (semiconductor chip)
3 ... Street 5 ... Resin film (filler)
6 ... Dividing groove 7 ... Protective seal (protective member)
125 ... Chuck table of the dividing device 217 ... Chuck table of the bump processing device 317 ... Chuck table of the grinding device

Claims (1)

A semiconductor wafer processing method for individually obtaining a device from a semiconductor wafer in which a plurality of electrodes protrude and a plurality of devices partitioned by streets are formed on the surface,
The filled with a filler made of resin on the surface of the semiconductor wafer, while embedded the electrode to the filler, the back surface side of the semiconductor wafer is held on the chuck table, wherein the surface of the semiconductor wafer streets And a half-cut process for forming a split groove having a depth corresponding to the thickness of the device to be obtained,
Electrode height alignment that holds the back side of the semiconductor wafer on a chuck table, scrapes off the tips of the plurality of electrodes together with the surface layer of the filler filled on the surface of the semiconductor wafer, and aligns the heights of these electrodes Process,
After cleaning the semiconductor wafer having the electrode height aligned in the electrode height aligning step, the surface of the semiconductor wafer is covered with a protective member, and the protective member side is held on a chuck table, and the semiconductor wafer is And a back surface grinding step of grinding the semiconductor wafer into individual devices by grinding the back surface side of the semiconductor wafer until the dividing grooves are exposed.

Images