JP2008264805A - Laser beam machining apparatus and laser beam machining method for adhesive film mounted on reverse side of wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining apparatus capable of efficiently breaking a die-bonding adhesive film mounted on the reverse side of a wafer that is divided into individual devices. <P>SOLUTION: The laser beam machining apparatus is equipped with: a chuck table 36; an image pickup means for imaging a workpiece held on the chuck table; a laser beam irradiation means for irradiating the workpiece with a laser beam; and a controller for controlling the laser beam irradiation means based on an image signal imaged by the image pickup means. The laser beam irradiation means is provided with: a laser beam oscillation means 6; an X axis galvano mirror 7a for deflecting the optical axis of the oscillated laser beam in the X axis direction; a Y axis galvano mirror 7b for deflecting it in the Y axis direction; a condenser that converges the laser beam deflected by the X axis and Y axis galvano mirrors and has an fθ lens 82 for vertically emitting to the holding face of the chuck table. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a laser processing apparatus for performing laser processing on a workpiece and a laser processing method for an adhesive film mounted on the back surface of a wafer.

  For example, in a semiconductor device manufacturing process, devices such as IC and LSI are formed in a plurality of regions partitioned by streets (division lines) formed in a lattice shape on the surface of a semiconductor wafer having a substantially disk shape, Individual devices are manufactured by dividing each region in which the devices are formed along a division line. As a dividing device for dividing a semiconductor wafer, a cutting device called a dicing device is generally used. This cutting device cuts a semiconductor wafer along a planned division line by a cutting blade having a thickness of about 40 μm. Devices divided in this way are packaged and widely used in electric devices such as mobile phones and personal computers.

A die-bonding adhesive film called a die attach film having a thickness of 70 to 80 μm formed of an epoxy resin or the like is mounted on the back surface of each of the divided devices, and the die supports the device through the adhesive film. Bonding is performed by heating the bonding frame. As a method of attaching an adhesive film for die bonding to the back surface of the device, the adhesive film is attached to the back surface of the semiconductor wafer, the semiconductor wafer is attached to the dicing tape through the adhesive film, and then the surface of the semiconductor wafer. By cutting the adhesive film together with the semiconductor wafer with a cutting blade along the planned division line, a device having the adhesive film mounted on the back surface is formed. (For example, refer to Patent Document 1.)
JP 2000-182959 A

  In recent years, electric devices such as mobile phones and personal computers are required to be lighter and smaller, and thinner devices are required. As a technique for dividing a device thinner, a so-called dicing method called a dicing method has been put into practical use. This tip dicing method is a semiconductor in which a dividing groove having a predetermined depth (a depth corresponding to the finished thickness of the device) is formed along the line to be divided from the surface of the semiconductor wafer and then the dividing groove is formed on the surface. This is a technique of grinding the back surface of a wafer to expose a dividing groove on the back surface to divide the wafer into individual devices, which can be processed to a thickness of 100 μm or less.

  However, when the semiconductor wafer is divided into individual devices by the tip dicing method, a dividing groove having a predetermined depth is formed along the line to be divided from the surface of the semiconductor wafer, and then the back surface of the semiconductor wafer is ground. Since the dividing groove is exposed on the back surface, an adhesive film for die bonding cannot be mounted on the back surface of the semiconductor wafer in advance. Therefore, when bonding a device manufactured by the previous dicing method to the die bonding frame, the bonding agent must be inserted between the device and the die bonding frame, and the bonding operation should be performed smoothly. There is a problem that can not be.

In order to solve such problems, an adhesive film for die bonding is attached to the back surface of the semiconductor wafer divided into individual devices by the pre-dicing method, and the semiconductor wafer is attached to the dicing tape through this adhesive film. Then, a method of manufacturing a semiconductor device in which a portion of the adhesive film exposed in the gap between the devices is removed by chemical etching, and a portion of the adhesive film exposed in the gap between the devices is formed. A method of manufacturing a semiconductor device has been proposed in which a laser beam is irradiated from the surface side of the device through the gap to remove a portion of the adhesive film exposed in the gap. (For example, see Patent Document 2.)
JP 2002-118081 A

  Therefore, the method of chemically etching and removing the portion of the adhesive film exposed in the gap between each device is not productive because it is necessary to mask the surface of each device. Further, in order to cut the adhesive film by irradiating a laser beam, the semiconductor wafer and the laser beam irradiation means are relatively moved for each dividing groove formed along the planned dividing line of the semiconductor wafer, so that the productivity is poor. There is.

  The present invention has been made in view of the above-mentioned facts, and its main technical problem is to efficiently break the bonding film for die bonding mounted on the back surface of the wafer divided into individual devices by the prior dicing method. An object of the present invention is to provide a laser processing apparatus and a laser processing method capable of performing the above.

In order to solve the above main technical problem, according to the present invention, a chuck table having a holding surface for holding a workpiece, an imaging means for imaging the workpiece held on the chuck table, and the chuck table In a laser processing apparatus comprising: a laser beam irradiation unit that irradiates a held workpiece with a laser beam; and a control unit that controls the laser beam irradiation unit based on an image signal imaged by the imaging unit.
The laser beam irradiation means includes a laser beam oscillation means that oscillates a laser beam, an X-axis galvanometer mirror that deflects the optical axis of the laser beam oscillated by the laser beam oscillation means in the X-axis direction, and an optical axis of the laser beam oscillated by the laser beam oscillation means A Y-axis galvanometer mirror that deflects the lens in the Y-axis direction, and an F-theta lens that focuses the laser beam deflected by the X-axis galvanometer mirror and the Y-axis galvanometer mirror and irradiates the chuck table vertically A concentrator equipped with,
A laser processing apparatus is provided.

Further, according to the present invention, a wafer in which a device is formed in a plurality of regions partitioned by a plurality of division lines formed in a lattice pattern on the surface is divided along the plurality of division lines. A laser processing method for forming a processing groove along the periphery of each device using the above laser processing apparatus on an adhesive film for die bonding mounted on the back surface of a wafer divided into the devices of
A wafer holding step for holding a wafer having an adhesive film mounted on the back surface on the chuck table;
A wafer imaging step in which the wafer held by the chuck table is positioned in an imaging region of the imaging means, and the wafer is imaged by the imaging means;
A machining area map creating step in which the control means creates a machining area map based on the image signal imaged in the wafer imaging process;
After performing the processing region map creation step, a wafer positioning step of positioning the wafer held on the chuck table and having an adhesive film attached to the back surface thereof in the laser beam irradiation region of the condenser of the laser beam oscillation means;
After performing the wafer positioning step, the control means operates the laser beam oscillation means based on the processing area map and controls the X-axis galvanometer mirror and the Y-axis galvanometer mirror, and passes the laser beam from the condenser between the devices. Including a laser beam irradiation step for irradiating the adhesive film,
A laser processing method for an adhesive film mounted on the back surface of a wafer is provided.

  According to the present invention, by controlling the X-axis galvanometer mirror and the Y-axis galvanometer mirror, it is possible to process a predetermined processing area without relatively moving the wafer as a workpiece and the laser beam irradiation means. Can be improved. Therefore, since the laser beam can be irradiated along the periphery of the individually divided devices without moving the wafer, the processed grooves can be efficiently formed in the adhesive film mounted on the back surface of the wafer. In addition, the condenser is equipped with an F-theta lens that condenses the laser beam deflected by the X-axis galvanometer mirror and the Y-axis galvanometer mirror and irradiates it perpendicularly to the holding surface of the chuck table. It is possible to irradiate the adhesive film through the devices divided into two.

  Hereinafter, a laser processing apparatus configured according to the present invention and a laser processing method for an adhesive film mounted on the back surface of a wafer will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a perspective view of a laser processing apparatus constructed according to the present invention. A laser processing apparatus shown in FIG. 1 includes a stationary base 2 and a chuck table mechanism 3 that is disposed on the stationary base 2 so as to be movable in a machining feed direction (X-axis direction) indicated by an arrow X and holds a workpiece. A laser beam irradiation unit support mechanism 4 disposed on the stationary base 2 so as to be movable in an index feed direction (Y-axis direction) indicated by an arrow Y perpendicular to the direction indicated by the arrow X (X-axis direction); The laser beam unit support mechanism 4 includes a laser beam irradiation unit 5 disposed so as to be movable in the direction indicated by the arrow Z (Z-axis direction).

  The chuck table mechanism 3 includes a pair of guide rails 31, 31 arranged on the stationary base 2 in parallel along the machining feed direction (X-axis direction) indicated by an arrow X, and the guide rails 31, 31. The first sliding block 32 arranged to be movable in the machining feed direction (X-axis direction) indicated by an arrow X, and the index feed direction (Y-axis direction) indicated by the arrow Y on the first sliding block 32 A second sliding block 33 movably disposed on the second sliding block 33, a cover table 35 supported on the second sliding block 33 by a cylindrical member 34, and a chuck table 36 as a workpiece holding means. ing. The chuck table 36 includes a suction chuck 361 formed of a porous material, and holds, for example, a disk-shaped semiconductor wafer, which is a workpiece, on a top surface which is a holding surface of the suction chuck 361 by suction means (not shown). It is like that. The chuck table 36 configured as described above is rotated by a pulse motor (not shown) disposed in the cylindrical member 34. The chuck table 36 is provided with a clamp 362 for fixing an annular frame described later.

  The first sliding block 32 has a pair of guided grooves 321 and 321 fitted to the pair of guide rails 31 and 31 on its lower surface, and an index feed direction indicated by an arrow Y on its upper surface ( A pair of guide rails 322 and 322 formed in parallel along the (Y-axis direction) are provided. The first sliding block 32 configured in this way is processed by the arrow X along the pair of guide rails 31, 31 when the guided grooves 321, 321 are fitted into the pair of guide rails 31, 31. It is configured to be movable in the feed direction (X-axis direction). The chuck table mechanism 3 in the illustrated embodiment includes a machining feed means 37 for moving the first sliding block 32 in the machining feed direction (X-axis direction) indicated by the arrow X along the pair of guide rails 31, 31. It has. The processing feed means 37 includes a male screw rod 371 disposed in parallel between the pair of guide rails 31 and 31, and a drive source such as a pulse motor 372 for rotationally driving the male screw rod 371. One end of the male screw rod 371 is rotatably supported by a bearing block 373 fixed to the stationary base 2, and the other end is connected to the output shaft of the pulse motor 372 by transmission. The male screw rod 371 is screwed into a penetrating female screw hole formed in a female screw block (not shown) provided on the lower surface of the central portion of the first sliding block 32. Accordingly, by driving the male screw rod 371 in the forward and reverse directions by the pulse motor 372, the first slide block 32 is moved along the guide rails 31 and 31 in the machining feed direction (X-axis direction) indicated by the arrow X. .

  The laser processing apparatus in the illustrated embodiment includes a processing feed amount detecting means 374 for detecting the processing feed amount of the chuck table 36. The processing feed amount detection means 374 includes a linear scale 374a disposed along the guide rail 31, and a read head disposed along the linear scale 374a along with the first sliding block 32 disposed along the first sliding block 32. 374b. In the illustrated embodiment, the reading head 374b of the feed amount detecting means 374 sends a pulse signal of one pulse every 1 μm to the control means described later. Then, the control means to be described later detects the machining feed amount of the chuck table 36 by counting the input pulse signals. Therefore, the machining feed amount detection unit 374 functions as an X-axis direction position detection unit that detects the X-axis direction position of the chuck table 36. When the pulse motor 372 is used as the drive source of the machining feed means 37, the machining feed amount of the chuck table 36 is counted by counting the drive pulses of the control means to be described later that outputs a drive signal to the pulse motor 372. Can also be detected. When a servo motor is used as a drive source for the machining feed means 37, a pulse signal output from a rotary encoder that detects the rotation speed of the servo motor is sent to a control means described later, and the pulse signal input by the control means. By counting, the machining feed amount of the chuck table 36 can also be detected.

  The second sliding block 33 is provided with a pair of guided grooves 331 and 331 which are fitted to a pair of guide rails 322 and 322 provided on the upper surface of the first sliding block 32 on the lower surface thereof. By fitting the guided grooves 331 and 331 to the pair of guide rails 322 and 322, the guided grooves 331 and 331 are configured to be movable in the indexing feed direction (Y-axis direction) indicated by the arrow Y. The chuck table mechanism 3 in the illustrated embodiment includes an index feed direction (Y-axis direction) indicated by an arrow Y along the pair of guide rails 322 and 322 provided on the first slide block 32. The first index feeding means 38 for moving to the first position is provided. The first index feed means 38 includes a male screw rod 381 disposed in parallel between the pair of guide rails 322 and 322, and a drive source such as a pulse motor 372 for rotating the male screw rod 381. It is out. One end of the male screw rod 381 is rotatably supported by a bearing block 383 fixed to the upper surface of the first sliding block 32, and the other end is connected to the output shaft of the pulse motor 382. The male screw rod 381 is screwed into a penetrating female screw hole formed in a female screw block (not shown) provided on the lower surface of the central portion of the second sliding block 33. Therefore, by driving the male screw rod 381 forward and backward by the pulse motor 382, the second slide block 33 is moved along the guide rails 322 and 322 in the indexing feed direction (Y-axis direction) indicated by the arrow Y. .

  The laser processing apparatus in the illustrated embodiment includes index feed amount detection means 384 for detecting the index processing feed amount of the second sliding block 33. The index feed amount detecting means 384 includes a linear scale 384a disposed along the guide rail 322 and a read head disposed along the linear scale 384a along with the second sliding block 33 disposed along the second sliding block 33. 384b. In the illustrated embodiment, the reading head 384b of the feed amount detection means 384 sends a pulse signal of one pulse every 1 μm to the control means described later. Then, the control means described later detects the index feed amount of the chuck table 36 by counting the input pulse signals. Accordingly, the index feed amount detection means 384 functions as a Y-axis direction position detection means for detecting the position of the chuck table 36 in the Y-axis direction. When the pulse motor 372 is used as the drive source of the index feed means 38, the index feed amount of the chuck table 36 is counted by counting the drive pulses of the control means to be described later that outputs a drive signal to the pulse motor 372. Can also be detected. Further, when a servo motor is used as the drive source of the first index feed means 38, a pulse signal output from a rotary encoder that detects the rotation speed of the servo motor is sent to the control means described later, and the control means inputs The index feed amount of the chuck table 36 can also be detected by counting the number of pulse signals.

  The laser beam irradiation unit support mechanism 4 includes a pair of guide rails 41, 41 arranged in parallel along the indexing feed direction (Y-axis direction) indicated by an arrow Y on the stationary base 2, and the guide rails 41, 41, A movable support base 42 is provided on 41 so as to be movable in the direction indicated by arrow Y. The movable support base 42 includes a movement support portion 421 that is movably disposed on the guide rails 41, 41, and a mounting portion 422 that is attached to the movement support portion 421. The mounting portion 422 is provided with a pair of guide rails 423 and 423 extending in parallel in a direction indicated by an arrow Z (Z-axis direction) on one side surface. The laser beam irradiation unit support mechanism 4 in the illustrated embodiment has a second index for moving the movable support base 42 along the pair of guide rails 41 and 41 in the index feed direction (Y-axis direction) indicated by the arrow Y. A feeding means 43 is provided. The second index feed means 43 includes a male screw rod 431 disposed in parallel between the pair of guide rails 41, 41, and a drive source such as a pulse motor 432 for rotationally driving the male screw rod 431. It is out. One end of the male screw rod 431 is rotatably supported by a bearing block (not shown) fixed to the stationary base 2, and the other end is connected to the output shaft of the pulse motor 432. The male screw rod 431 is screwed into a female screw hole formed in a female screw block (not shown) provided on the lower surface of the central portion of the moving support portion 421 constituting the movable support base 42. Therefore, the movable support base 42 is moved along the guide rails 41 and 41 in the indexing feed direction (Y-axis direction) indicated by the arrow Y by driving the male screw rod 431 forward and backward by the pulse motor 432. .

  The laser beam irradiation unit 5 in the illustrated embodiment includes a unit holder 51 and laser beam irradiation means 52 attached to the unit holder 51. The unit holder 51 is provided with a pair of guided grooves 511 and 511 that are slidably fitted to a pair of guide rails 423 and 423 provided in the mounting portion 422. By being fitted to the guide rails 423 and 423, the guide rails 423 and 423 are supported so as to be movable in the direction indicated by the arrow Z (Z-axis direction).

  The laser beam irradiation unit 5 in the illustrated embodiment includes a moving means 53 for moving the unit holder 51 along the pair of guide rails 423 and 423 in the direction indicated by the arrow Z (Z-axis direction). The moving means 53 includes a male screw rod (not shown) disposed between the pair of guide rails 423 and 423, and a drive source such as a pulse motor 532 for rotationally driving the male screw rod. By driving the male screw rod (not shown) in the forward and reverse directions by the motor 532, the unit holder 51 and the laser beam irradiation means 52 are moved along the guide rails 423 and 423 in the direction indicated by the arrow Z (Z-axis direction). In the illustrated embodiment, the laser beam irradiation means 52 is moved upward by driving the pulse motor 532 forward, and the laser beam irradiation means 52 is moved downward by driving the pulse motor 532 in reverse. Yes.

  The laser beam irradiating means 52 includes a cylindrical casing 521 arranged substantially horizontally, a pulse laser beam oscillating means 6 arranged in the casing 521 as shown in FIG. 2, and the laser beam oscillating means 6 oscillated. An X-axis galvano mirror 7a for deflecting the optical axis of the laser beam in the X-axis direction, a Y-axis galvano mirror 7b for deflecting the optical axis of the laser beam oscillated by the laser beam oscillation means 6 in the Y-axis direction, the X-axis galvano mirror 7a and A condenser 8 is provided for condensing the laser beam deflected by the Y-axis galvanometer mirror 7 b and irradiating the workpiece held on the chuck table 36.

  The pulse laser beam oscillating means 6 comprises a pulse laser beam oscillator 61 comprising a YAG laser oscillator or a YVO4 laser oscillator, and a repetition frequency setting means 62 attached thereto. The pulse laser beam oscillator 61 oscillates a pulse laser beam (LB) having a predetermined frequency set by the repetition frequency setting means 62.

  The X-axis galvanometer mirror 7a includes a mirror 71a and an angle adjustment actuator 72a that adjusts the installation angle of the mirror 71a. The X-axis galvanometer mirror 7a configured in this way controls the angle adjusting actuator 72a by the control means described later and adjusts the installation angle of the mirror 71a, whereby the optical axis of the laser beam oscillated by the laser beam oscillation means 6 is set in the X-axis direction. Let it deflect. Similarly to the X-axis galvanometer mirror 7a, the Y-axis galvanometer mirror 7b is also composed of a mirror 71b and an angle adjusting actuator 72b for adjusting the installation angle of the mirror 71b. The Y-axis galvanometer mirror 7b configured as described above controls the angle adjusting actuator 72b by the control means described later to adjust the installation angle of the mirror 71b, so that the optical axis of the laser beam oscillated by the laser beam oscillation means 6 is set in the Y-axis direction. Let it deflect.

  The condenser 8 collects the direction change mirror 81 for changing the direction of the laser beam deflected by the X axis galvanometer mirror 7a and the Y axis galvanometer mirror 7b downward, and the laser beam changed in direction by the direction change mirror 81. An F-theta lens (fθ lens) 82 that emits light and irradiates perpendicularly to the holding surface of the chuck table 36 is provided. For example, an F-theta lens (fθ lens) 82 having a diameter of about 100 mm is used. The concentrator 8 configured in this manner is attached to the tip of the casing 521 as shown in FIG.

  Referring back to FIG. 1, the laser processing apparatus in the illustrated embodiment includes an imaging unit 9 that is disposed at the front end portion of the casing 521 and images a processing region to be laser processed by the laser beam irradiation unit 52. Yes. The image pickup means 9 is composed of an image pickup device (CCD) or the like, and sends the picked up image signal to the control means 10.

  The control means 10 is constituted by a computer, and includes a central processing unit (CPU) 101 that performs arithmetic processing according to a control program, a read only memory (ROM) 102 that stores a control program and the like, a control map and a workpiece to be described later. A random access memory (RAM) 103 capable of storing design value data, operation results, and the like, a counter 104, an input interface 105, and an output interface 106. Detection signals from the machining feed amount detection means 374, the index feed amount detection means 384, the imaging means 9 and the like are input to the input interface 105 of the control means 10. From the output interface 106 of the control means 10, the pulse motor 372, the pulse motor 382, the pulse motor 432, the pulse motor 532, the pulse laser beam oscillation means 6, the angle adjusting actuator 72a of the X-axis galvanometer mirror 7a, and the Y-axis galvanometer mirror. A control signal is output to the angle adjusting actuator 72b of 7b. The random access memory (RAM) 103 includes a first storage area 103a for storing a processing area map created based on an image signal picked up by the image pickup means 9 and other storage areas.

  Before explaining the laser processing for forming the processing groove in the adhesive film for die bonding mounted on the back surface of the wafer using the laser processing apparatus configured as described above, the wafer is divided into individual devices, A method for mounting an adhesive film on the back surface of a wafer divided into individual devices will be described.

  FIG. 3 is a perspective view of a semiconductor wafer as a wafer. A semiconductor wafer 20 shown in FIG. 3 is made of, for example, a silicon wafer having a thickness of 600 μm, and a plurality of division lines 21 are formed in a lattice shape on the surface 20a. On the surface 2a of the semiconductor wafer 2, devices 22 such as ICs and LSIs are formed in a plurality of regions partitioned by a plurality of division lines 21 formed in a lattice shape.

  The semiconductor wafer 2 shown in FIG. 3 is divided into individual devices 22 by performing a wafer dividing process by a so-called tip dicing method. In the wafer dividing step by the pre-dicing method, first, a dividing groove having a predetermined depth (a depth corresponding to the finished thickness of each device) is formed along the planned dividing line 21 formed on the surface 20a of the semiconductor wafer (dividing). Groove forming step). This dividing groove forming step is carried out using a cutting device 3 shown in FIG. A cutting apparatus 30 shown in FIG. 4A includes a chuck table 301 provided with a suction holding means, a cutting means 303 provided with a cutting blade 302, and an imaging means 304. In order to perform the dividing groove forming step, the semiconductor wafer 20 is placed on the chuck table 301 with the front surface 20a facing upward. Then, the semiconductor wafer 20 is held on the chuck table 301 by operating a suction means (not shown). In this way, the chuck table 301 that sucks and holds the semiconductor wafer 20 is positioned directly below the imaging means 304 by a cutting feed mechanism (not shown).

  When the chuck table 301 is positioned immediately below the image pickup means 304, an alignment operation for detecting a cutting region in which the division grooves of the semiconductor wafer 20 are to be formed is executed by the image pickup means 304 and a control means (not shown). That is, the imaging unit 304 and a control unit (not shown) execute image processing such as pattern matching for aligning the division line 21 formed in a predetermined direction of the semiconductor wafer 20 with the cutting blade 302, Align the cutting area (alignment process). In addition, the alignment of the cutting area is similarly performed on the division line 21 that is formed on the semiconductor wafer 20 and extends at right angles to the predetermined direction.

  When the cutting area alignment of the semiconductor wafer 20 held on the chuck table 301 is performed as described above, the chuck table 301 holding the semiconductor wafer 20 is moved to the cutting start position of the cutting area. Then, the cutting blade 302 is moved downward while rotating in the direction indicated by the arrow 302a in FIG. The cutting feed position is set such that the outer peripheral edge of the cutting blade 302 is a depth position (for example, 110 μm) corresponding to the finished thickness of the device from the surface of the semiconductor wafer 20. When the cutting blade 302 is cut and fed in this way, the chuck table 301 is cut and fed in the direction indicated by the arrow X in FIG. As shown in FIG. 5B, a dividing groove 210 having a depth (for example, 110 μm) corresponding to the finished thickness of the device is formed along the dividing line 21 (dividing groove forming step). This division groove forming step is performed along all the division lines 21 formed in the semiconductor wafer 20.

  When the dividing groove 210 having a predetermined depth is formed on the surface 20a of the semiconductor wafer 20 along the planned dividing line 21 by the above-described dividing groove forming step, the semiconductor wafer 20 of the semiconductor wafer 20 is formed as shown in FIGS. The protective member 40 for grinding is stuck on the surface 20a (surface on which the device 22 is formed) (protective member sticking step). In the illustrated embodiment, the protective member 40 is a polyolefin sheet having a thickness of 150 μm.

  Next, the back surface 20b of the semiconductor wafer 20 having the protective member 40 attached to the front surface is ground, and the divided grooves 210 are exposed on the back surface 20b to be divided into individual devices (divided groove exposing step). As shown in FIG. 6A, the divided groove exposing step is performed by a grinding device 50 including a grinding means 503 having a chuck table 501 and a grinding wheel 502. That is, the back surface 20b of the semiconductor wafer 20 is held on the chuck table 501. For example, the grinding wheel 502 of the grinding means 503 is indicated by 502a while the chuck table 501 is rotated at 300 rpm in the direction indicated by the arrow 501a. Then, it is ground by rotating at 6000 rpm and coming into contact with the back surface 20b of the semiconductor wafer 20, and grinding is performed until the dividing groove 210 appears on the back surface 20b as shown in FIG. Thus, by grinding until the dividing groove 210 is exposed, the semiconductor wafer 20 is divided into individual devices 22 as shown in FIG. In addition, since the protection member 40 is stuck on the surface of the plurality of divided devices 22, the form of the semiconductor wafer 20 is maintained without being separated.

  If the semiconductor wafer 20 is divided into individual devices 22 by performing the wafer dividing step by the above-described dicing method, an adhesive film for die bonding is applied to the back surface 20b of the semiconductor wafer 20 divided into the individual devices 22. The adhesive film mounting process to mount is implemented. That is, as shown in FIGS. 7A and 7B, the adhesive film 60 is mounted on the back surface 20 b of the semiconductor wafer 20 divided into individual devices 22. At this time, as described above, the adhesive film 60 is pressed and adhered to the back surface 20b of the semiconductor wafer 20 while being heated at a temperature of 80 to 200 ° C.

  When the adhesive film mounting process is performed as described above, the surface of the dicing tape T mounted on the annular frame F is disposed on the side of the semiconductor wafer 20 on which the adhesive film 60 is mounted as shown in FIG. A wafer support process for attaching to the wafer is carried out. Then, the protective member 40 attached to the surface 20a of the semiconductor wafer 20 is peeled off (protective member peeling step). In addition, when using the dicing tape with the adhesive film by which the adhesive film was previously stuck on the surface of the dicing tape, the semiconductor wafer 20 divided into the individual devices 22 by performing the wafer dividing step described above is used. An adhesive film attached to the surface of the dicing tape is attached to the back surface 20b. And the said protection member peeling process is implemented.

  As described above, when the adhesive film 60 is attached to the back surface 20b of the semiconductor wafer 20 divided into the individual devices 22, the laser beam is transmitted through the devices to the adhesive film 60 using the laser processing apparatus described above. Irradiation and laser processing for forming laser processing grooves in the adhesive film 60 are performed. In order to carry out this laser processing, a semiconductor wafer (adhesive film 60 is mounted on the back surface) supported on an annular frame F via a dicing tape T as shown in FIG. 8 is shown in FIG. The dicing tape T side is placed on the chuck table 36 of the laser processing apparatus. Then, by operating a suction means (not shown), the semiconductor wafer 20 is sucked and held on the chuck table 36 via the dicing tape T. The annular frame F is fixed by a clamp 362.

  As described above, the chuck table 36 that sucks and holds the semiconductor wafer 20 is positioned in the imaging region immediately below the imaging unit 9 by the processing feed unit 37. When the chuck table 36 is positioned immediately below the imaging means 9, the semiconductor wafer 20 on the chuck table 36 is in a state positioned at the coordinate position shown in FIG. In this state, the control unit 10 outputs an imaging command signal to the imaging unit 9. Based on this imaging command signal, the imaging means 9 images the semiconductor wafer 20 and sends the captured image signal to the control means 10 (wafer imaging process).

  If the wafer imaging process described above is performed, the control means 10 partitions the area 22 to be processed based on the image signal sent from the imaging means 9, that is, the devices 22 individually divided in the semiconductor wafer 20 shown in FIG. The X and Y coordinates of the dividing groove 210 to be obtained are obtained, and a machining area map is created (machining area map creation step). Then, the control means 10 stores the created processing area map in the first storage area 103 a of the random access memory (RAM) 103.

  Next, the control unit 10 operates the processing feeding unit 37 and the first indexing feeding unit 38 to move the chuck table 36, and a predetermined processing region of the semiconductor wafer 20 held by the chuck table 36 is collected in the condenser 8. A wafer positioning step is performed for positioning in the laser beam irradiation area. This wafer positioning process will be described with reference to FIG. The semiconductor wafer 20 shown in FIG. 10 has a diameter of about 100 mm and is divided into four processing regions A, B, C, and D. First, the control unit 10 operates the processing feeding unit 37 and the first indexing feeding unit 38 to position the processing region A of the semiconductor wafer 20 held by the chuck table 36 directly below the condenser 8.

  In this way, when the processing area A is positioned immediately below the condenser 8, the control means 10 operates the pulse laser beam oscillation means 6 of the laser beam irradiation means 52 and the angle adjustment actuator for the X-axis galvano mirror 7a. The angle adjustment actuator 72b of the 72a and the Y-axis galvanometer mirror 7b is controlled based on the processing area map stored in the first storage area 103a. As a result, the pulsed laser beam LB condensed by the f-theta lens (fθ lens) 82 of the condenser 8 is bonded through the dividing grooves 210 that define the individually divided devices 22 in the semiconductor wafer 20 as shown in FIG. The film 60 is irradiated (laser beam irradiation step). At this time, the focused point of the pulse laser beam LB condensed by the F-theta lens (fθ lens) 82 is applied to the upper surface of the adhesive film 60 for irradiation. In addition, the wavelength of this laser beam is set to a wavelength that absorbs the adhesive film 60. As a result, as shown in FIG. 11, the laser processing groove 600 is formed along the dividing groove 210 in the adhesive film 60. In this laser beam irradiation step, the F-theta lens (fθ lens 82) that condenses the laser beam deflected by the X-axis galvanometer mirror 7a and the Y-axis galvanometer mirror 7b is focused on the holding surface of the chuck table 36. Therefore, the adhesive film 60 can be reliably irradiated through the dividing grooves 210 that partition the individually divided devices 22 in the semiconductor wafer 20. As described above, in the laser beam irradiation step, a predetermined processing region can be processed without relatively moving the semiconductor wafer 20 as the workpiece and the laser beam irradiation means 52, so that productivity can be improved. .

In addition, the processing conditions in the said laser beam irradiation process are set as follows, for example.
Type of laser beam: LD excitation Q-switched YAG laser Wavelength: 355nm
Repetition frequency: 100 kHz
Average output: 10W
Condensing spot diameter: φ15μm

  As described above, if the laser beam irradiation process is performed on the processing area A of the semiconductor wafer 20 held by the chuck table 36, the laser beam irradiation process is similarly performed on the processing areas B, C, and D. To do.

  As described above, when the laser beam irradiation process is performed on all the processing areas A, B, C, and D of the semiconductor wafer 20 held on the chuck table 36, the dicing tape T is expanded to attach the adhesive film 60 to the device. An adhesive film separation step for separating each time is performed. In the illustrated embodiment, this adhesive film separation step is performed using a tape expansion device 70 shown in FIG. 12 includes a frame holding means 710 for holding the annular frame F, and a tape extending means for expanding the dicing tape T attached to the annular frame F held by the frame holding means 710. 720. The frame holding means 710 includes an annular frame holding member 711 and a plurality of clamps 712 as fixing means disposed on the outer periphery of the frame holding member 711. An upper surface of the frame holding member 711 forms a mounting surface 711a for mounting the annular frame F, and the annular frame 4 is mounted on the mounting surface 711a. The annular frame F placed on the placement surface 711 a is fixed to the frame holding member 711 by the clamp 712. The frame holding means 710 configured as described above is supported by the tape expanding means 720 so as to be able to advance and retract in the vertical direction.

  The tape expansion means 720 includes an expansion drum 721 disposed inside the annular frame holding member 711. The expansion drum 721 has an inner diameter and an outer diameter that are smaller than the inner diameter of the annular frame F and larger than the outer diameter of the semiconductor wafer 20 attached to the dicing tape T attached to the annular frame F. The expansion drum 721 includes a support flange 722 at the lower end. The tape expansion means 720 in the illustrated embodiment includes support means 730 capable of moving the annular frame holding member 711 up and down in the vertical direction. The support means 730 includes a plurality of air cylinders 731 disposed on the support flange 722, and the piston rod 732 is connected to the lower surface of the annular frame holding member 711. As described above, the support unit 730 including the plurality of air cylinders 731 has a predetermined amount from the reference position where the mounting surface 711a is substantially flush with the upper end of the expansion drum 721 and the upper end of the expansion drum 721. Move up and down between the lower extended positions. Therefore, the support unit 730 including the plurality of air cylinders 731 functions as an expansion movement unit that relatively moves the expansion drum 721 and the frame holding member 711 in the vertical direction.

  The adhesive film separation process implemented using the tape expansion apparatus 70 comprised as mentioned above is demonstrated with reference to FIG. That is, the annular frame F on which the dicing tape T to which the adhesive film 60 side of the semiconductor wafer 20 (divided into the individual devices 22 along the scheduled division line 21) is attached is attached to (FIG. As shown to a), it mounts on the mounting surface 711a of the frame holding member 711 which comprises the frame holding means 710, and it fixes to the frame holding member 711 with the clamp 712. At this time, the frame holding member 711 is positioned at the reference position shown in FIG. Next, the plurality of air cylinders 731 as the support means 730 constituting the tape expansion means 720 are operated, and the annular frame holding member 711 is lowered to the expansion position shown in FIG. Accordingly, the annular frame F fixed on the mounting surface 711a of the frame holding member 711 is also lowered, so that the dicing tape T attached to the annular frame F is an expansion drum as shown in FIG. It is expanded in contact with the upper edge of 721 (tape expansion process). As a result, the tensile force acts radially on the adhesive film 60 adhered to the dicing tape T. Thus, when a tensile force acts on the adhesive film 60 in a radial manner, the semiconductor wafer 20 is divided into individual devices 22 along the planned division line 21, so that the space between the individual devices 22 is widened and a space S is formed. The For this reason, since a tensile force acts on the adhesive film 60, even if the adhesive film 6 is not completely cut in the laser beam irradiation step, the adhesive film 60 is broken with the laser processing groove 600 as a base point and separated for each device 22. Further, when the adhesive film 60 is completely cut in the wafer cutting step, the adhesive film 60 is surely provided for each device 22 by forming the gap S between the individual devices 22 by the tape expansion step. To be separated.

The perspective view of the laser processing apparatus comprised according to this invention. The block diagram of a structure of the laser beam irradiation means with which the laser processing apparatus shown in FIG. 1 is equipped. The perspective view which shows the semiconductor wafer as a wafer. Explanatory drawing of the division | segmentation groove | channel formation process in the tip dicing method which divides | segments the semiconductor wafer shown in FIG. 3 into each device. Explanatory drawing of the protection member sticking process in the tip dicing method which divides | segments the semiconductor wafer shown in FIG. 3 into each device. Explanatory drawing of the division | segmentation groove | channel exposure process in the tip dicing method which divides | segments the semiconductor wafer shown in FIG. 3 into each device. Explanatory drawing of the adhesive film mounting process which mounts the adhesive film for die bonding on the back surface of the semiconductor wafer divided | segmented into each device by the front dicing method. FIG. 8 is an explanatory view of a wafer support process for adhering the semiconductor wafer on which the adhesive film mounting process shown in FIG. 7 has been performed to the surface of a dicing tape mounted on an annular frame. FIG. 9 is an explanatory diagram showing a relationship with coordinates in a state where the semiconductor wafer shown in FIG. 8 is held at a predetermined position of the chuck table of the laser processing apparatus shown in FIG. 1. Explanatory drawing of the wafer positioning process in the laser processing method of the adhesive film with which the back surface of the wafer by this invention was mounted | worn. Explanatory drawing of the laser beam irradiation process in the laser processing method of the adhesive film with which the back surface of the wafer by this invention was mounted | worn. The perspective view of the take expansion apparatus which expands a dicing tape, after implementing the laser beam irradiation process in the laser processing method of the adhesive film with which the back surface of the wafer by this invention was mounted | worn. Explanatory drawing of the adhesive film separation process implemented using the take expansion apparatus shown in FIG.

Explanation of symbols

3: Chuck table mechanism 36: Chuck table 37: Work feed means 374: Work feed amount detection means 38: First index feed means 384: Index feed amount detection means 4: Laser beam irradiation unit support mechanism 42: Movable support base 43 : Second index feeding means 5: Laser beam irradiation unit 52: Laser beam irradiation means 6: Laser beam oscillation means 7a: X-axis galvanometer mirror 7b: Y-axis galvanometer mirror 8: Condenser 81: Direction conversion mirror 82: F-theta lens ( fθ Talens)
9: Imaging means 10: Control means 20: Semiconductor wafer 21: Planned division line 22: Device 30: Cutting apparatus 301: Chuck table 302 of cutting apparatus: Cutting blade 303: Cutting means 40: Protection member 50: Grinding apparatus 501: Grinding Chuck table 502: grinding wheel 503: grinding means 60: adhesive film 70: tape expansion device 710: frame holding means 720: tape expansion means 730: support means
F: Ring frame
T: Dicing tape

Claims (2)

A chuck table having a holding surface for holding the workpiece, an imaging means for imaging the workpiece held on the chuck table, and a laser beam irradiation means for irradiating the workpiece held on the chuck table with a laser beam A laser processing apparatus comprising a control means for controlling the laser beam irradiation means based on an image signal picked up by the image pickup means;
The laser beam irradiation means includes a laser beam oscillation means that oscillates a laser beam, an X-axis galvanometer mirror that deflects the optical axis of the laser beam oscillated by the laser beam oscillation means in the X-axis direction, and an optical axis of the laser beam oscillated by the laser beam oscillation means A Y-axis galvanometer mirror that deflects the X-axis in the Y-axis direction, and an F-theta lens that condenses the laser beam deflected by the X-axis galvanometer mirror and the Y-axis galvanometer mirror and irradiates the holding surface of the chuck table perpendicularly A concentrator equipped with,
Laser processing equipment characterized by that. A wafer in which devices are formed in a plurality of regions partitioned by a plurality of division lines formed in a lattice pattern on the surface is divided along the plurality of division lines, and the wafers divided into individual devices A laser processing method for forming a processing groove along the periphery of each device using the laser processing apparatus on the adhesive film for die bonding mounted on the back surface,
A wafer holding step for holding a wafer having an adhesive film mounted on the back surface on the chuck table;
A wafer imaging step in which the wafer held by the chuck table is positioned in an imaging region of the imaging means, and the wafer is imaged by the imaging means;
A machining area map creating step in which the control means creates a machining area map based on the image signal imaged in the wafer imaging process;
After performing the processing region map creation step, a wafer positioning step of positioning the wafer held on the chuck table and having an adhesive film attached to the back surface thereof in the laser beam irradiation region of the condenser of the laser beam oscillation means;
After performing the wafer positioning step, the control means operates the laser beam oscillation means based on the processing area map and controls the X-axis galvanometer mirror and the Y-axis galvanometer mirror, and passes the laser beam from the condenser between the devices. Including a laser beam irradiation step for irradiating the adhesive film,
A laser processing method for an adhesive film mounted on the back surface of a wafer, characterized in that:

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