JP2006286763A - Laser machining method and laser machining apparatus for wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser machining method and a laser machining apparatus for wafers by which the wafer can be machined by laser while the surface of the wafer to be machined is uniformly covered with a protection film. <P>SOLUTION: The laser machining method is used to machine a wafer by laser along a lattice-like streets to divide the wafer into devices wherein a plurality of devices are formed like a matrix on its surface. It includes a protection film covering step to spray a liquid resin on the machining surface of the wafer and cover the protection film, and a laser light irradiation step to give a laser light to the machining surface of the wafer wherein the protection cover is formed, along the streets through the protection film. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wafer laser processing method and a laser processing apparatus for performing laser processing on a processing surface of a wafer such as a semiconductor wafer or an optical device wafer.

  As is well known to those skilled in the art, in the semiconductor device manufacturing process, a plurality of semiconductor chips such as ICs and LSIs are formed in a matrix by a laminated body in which an insulating film and a functional film are laminated on the surface of a semiconductor substrate such as silicon. A semiconductor wafer is formed. In the semiconductor wafer formed in this way, the semiconductor chip is partitioned by dividing lines called streets, and individual semiconductor chips are manufactured by cutting along the streets. In addition, an optical device wafer in which a plurality of regions are defined by streets formed in a lattice pattern on the surface of a sapphire substrate or the like, and an optical device in which a gallium nitride compound semiconductor or the like is stacked in the partitioned region is It is divided into optical devices such as individual light-emitting diodes and laser diodes along the planned dividing line, and is widely used in electrical equipment.

  Such cutting along the streets of a wafer such as a semiconductor wafer or an optical device wafer is usually performed by a cutting device called a dicer. This cutting apparatus includes a chuck table for holding a semiconductor wafer as a workpiece, a cutting means for cutting the semiconductor wafer held on the chuck table, and a movement for relatively moving the chuck table and the cutting means. Means. The cutting means includes a rotating spindle that is rotated at a high speed and a cutting blade attached to the spindle.

On the other hand, in recent years, as a method of dividing a plate-like workpiece such as a semiconductor wafer, a laser processing groove is formed by irradiating a pulse laser beam along a street formed on the workpiece, and along this laser processing groove. A method of cleaving with a mechanical braking device has been proposed. (For example, refer to Patent Document 1.)
JP-A-10-305420

  Laser processing can increase the processing speed as compared to cutting, and can relatively easily process even a wafer made of a material having a high Mohs hardness such as sapphire. However, when laser light is irradiated along the street of the wafer, thermal energy concentrates on the irradiated area and debris is generated. This debris adheres to the bonding pads connected to the circuit and degrades the quality of the chip. New problems arise.

In order to solve the problem caused by the debris, there has been proposed a laser processing method in which a processed film of a wafer is coated with a protective film such as polyvinyl alcohol, and the wafer is irradiated with a laser beam through the protective film. (For example, see Patent Document 2.)
JP 2004-188475 A

  In the above publication, as shown in FIG. 9A, a predetermined amount of liquid resin L is dropped from a resin supply nozzle N onto the center of a wafer W held on a spinner table T, and the spinner table T is moved at a predetermined speed. A spinner coating method in which a liquid resin is coated on a processed surface of a wafer W by rotating is disclosed.

  Thus, as shown in FIG. 9B, since the circuit D or the like is formed on the surface of the wafer W and there are irregularities, the spinner table T holding the wafer W is rotated, and the liquid is generated by the centrifugal force. Even if the resin L is caused to flow toward the outer peripheral portion, it is difficult to uniformly coat the surface of the wafer W with the liquid resin. Even when the above spinner coating is performed in a state where a plurality of relatively small-diameter wafers are arranged on the support member, such as a sapphire wafer, a protective film made of resin is uniformly coated on the surfaces of the plurality of wafers. Is difficult.

  The present invention has been made in view of the above-mentioned facts, and the main technical problem is to provide a wafer laser processing method and a laser processing apparatus capable of performing laser processing by uniformly covering a surface of a wafer with a protective coating. Is to provide.

In order to solve the above-mentioned main technical problem, according to the present invention, a wafer laser processing method for performing laser processing along a lattice-shaped street of a wafer having a plurality of devices formed in a matrix on the surface thereof. Because
A protective coating coating step of spraying a liquid resin on the processed surface of the wafer by spraying to coat the protective coating;
A laser beam irradiation step of irradiating a laser beam along the street through the protective coating on the processed surface of the wafer on which the protective coating is formed,
A wafer laser processing method is provided.

  The liquid resin is preferably a water-soluble resin.

Further, according to the present invention, the chuck table for holding the workpiece, the laser beam irradiation means for irradiating the workpiece held on the chuck table with a laser beam, the chuck table and the laser beam irradiation means relative to each other. In a laser processing apparatus comprising a processing feed means for processing and feeding to
A spray nozzle that is disposed along a movement path of the chuck table and sprays a liquid resin onto a surface of a workpiece held by the chuck table;
A resin supply means for supplying a liquid resin to the spray nozzle,
A laser processing apparatus is provided.

    According to the present invention, since a liquid resin is sprayed on the surface of the wafer to cover the protective coating, even if the surface of the wafer is uneven or a plurality of wafers are disposed, A protective coating can be formed uniformly over the entire surface. Therefore, the laser processing for irradiating the laser beam through the protective coating is uniform.

  Preferred embodiments of a wafer laser processing method and a laser processing apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a perspective view of a laser processing apparatus equipped with a protective film forming and cleaning means for carrying out the protective film coating method according to the present invention.
The laser processing apparatus shown in FIG. 1 includes an apparatus housing 1 having a substantially rectangular parallelepiped shape. In the apparatus housing 1, there are a stationary base 2 shown in FIG. 2 and a chuck table that is disposed on the stationary base 2 so as to be movable in a direction indicated by an arrow X that is a machining feed direction and holds a workpiece. The chuck table mechanism 3 provided, and a laser beam irradiation unit disposed on the stationary base 2 so as to be movable in a direction indicated by an arrow Y that is an indexing feed direction (a direction orthogonal to a direction indicated by an arrow X that is a processing feed direction) The support mechanism 4 and the laser beam irradiation unit support mechanism 4 are provided with a laser beam irradiation unit 5 disposed so as to be movable in the direction indicated by the arrow Z in the vertical direction in the drawing.

  The chuck table mechanism 3 includes a pair of guide rails 31, 31 arranged in parallel along the machining feed direction indicated by the arrow X on the stationary base 2, and the arrow X on the guide rails 31, 31. A first slide block 32 movably disposed in the processing feed direction; and a second slide block 33 disposed on the first slide block 32 movably in the index feed direction indicated by an arrow Y; A support table 35 supported by a cylindrical member 34 on the second sliding block 33 and a chuck table 36 as a workpiece holding means are provided. The chuck table 36 includes a suction chuck 361 formed of a porous material, and a wafer as a workpiece is held on the suction chuck 361 by suction means (not shown). 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 is provided with a pair of guided grooves 321 and 321 fitted to the pair of guide rails 31 and 31 on the lower surface thereof, and in the index feed direction indicated by an arrow Y on the upper surface thereof. A pair of guide rails 322 and 322 formed in parallel with each other 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. The chuck table mechanism 3 in the illustrated embodiment includes a machining feed means 37 for moving the first sliding block 32 along the pair of guide rails 31 and 31 in the machining feed direction indicated by the arrow X. 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. Therefore, when the male screw rod 371 is driven to rotate forward and backward by the pulse motor 372, the first sliding block 32 is moved along the guide rails 31, 31 in the machining feed 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 processing feed amount detection means 374 sends a pulse signal of 1 pulse to the control means described later for every 1 μm. Then, the control means to be described later detects the machining feed amount of the chuck table 36 by counting the input pulse signals. 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 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. Is counted, the machining feed amount of the chuck table 36 can 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 and feeding direction indicated by the arrow Y. The chuck table mechanism 3 in the illustrated embodiment is for moving the second slide block 33 along the pair of guide rails 322 and 322 provided in the first slide block 32 in the index feed direction indicated by the arrow Y. First index feeding means 38 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 382 for rotationally driving 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, when the male screw rod 381 is driven to rotate forward and reversely by the pulse motor 382, the second slide block 33 is moved along the guide rails 322 and 322 in the index feed 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 feed amount of the second sliding block 33. The index feed amount detection means 384 includes a linear scale 384a disposed along the guide rail 322 and a reading head 384b disposed on the second sliding block 33 and moving along the linear scale 384a. In the illustrated embodiment, the reading head 384b of the index feed amount detection means 384 sends a pulse signal of 1 pulse to the control means described later for every 1 μm. And the control means mentioned later detects the index feed amount of the laser beam irradiation unit 5 by counting the input pulse signal. When the pulse motor 382 is used as the drive source of the first indexing and feeding means 38, the laser beam irradiation unit 5 is counted by counting the drive pulses of the control means to be described later that outputs a drive signal to the pulse motor 382. The index feed amount can be detected. When a servo motor is used as the drive source for the second indexing and feeding 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, which will be described later. By counting the pulse signals, the index feed amount of the second sliding block 33, that is, the chuck table 36 can be detected.

  The laser beam irradiation unit support mechanism 4 includes a pair of guide rails 41, 41 arranged in parallel along the indexing feed direction indicated by the arrow Y on the stationary base 2, and the arrow Y on the guide rails 41, 41. The movable support base 42 is provided so as to be movable in the direction indicated by. 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 the direction indicated by the arrow Z on one side surface in parallel. The laser beam irradiation unit support mechanism 4 in the illustrated embodiment includes a second index feed means 43 for moving the movable support base 42 along the pair of guide rails 41, 41 in the index feed direction indicated by the arrow Y. is doing. 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. For this reason, when the male screw rod 431 is driven to rotate forward and backward by the pulse motor 432, the movable support base 42 is moved along the guide rails 41, 41 in the index feed direction indicated by the arrow Y.

  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.

  The illustrated laser beam irradiation means 52 irradiates a pulsed laser beam from a condenser 522 attached to the tip of a cylindrical casing 521 arranged substantially horizontally. An alignment means 6 for detecting a processing region to be laser processed by the laser beam irradiation means 52 is disposed at the front end portion of the casing 521 constituting the laser beam irradiation means 52. The alignment unit 6 includes an illuminating unit that illuminates the workpiece, an optical system that captures an area illuminated by the illuminating unit, an imaging device (CCD) that captures an image captured by the optical system, and the like. The captured image signal is sent to the control means described later.

  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. 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. 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. It has become.

Returning to FIG. 1, the description will continue. The illustrated laser processing apparatus includes a cassette mounting portion 8a on which a cassette for storing a wafer as a workpiece is mounted. A cassette table 8 is disposed on the cassette mounting portion 8a so as to be movable up and down by lifting means (not shown). A cassette 9 is mounted on the cassette table 8. The wafer accommodated in the cassette 9 is composed of a semiconductor wafer 10 in the illustrated embodiment as shown in FIG. The semiconductor wafer 10 has a plurality of devices 101 formed in a matrix on the surface 10a. Each device 101 is partitioned by streets 102 formed in a lattice shape. The back surface of the semiconductor wafer 10 is adhered to the protective tape 12 mounted on the annular frame 11 with the front surface 10a as the processing surface facing upward (frame support step). When processing the semiconductor wafer 10 from the back side, the front surface 10 a of the semiconductor wafer 10 is stuck to the protective tape 12. As described above, the semiconductor wafer 10 is accommodated in the cassette 9 in a state of being supported by the annular frame 11 via the protective tape 12.
FIG. 4 shows another embodiment of a wafer that is a workpiece. The wafer shown in FIG. 4 includes an optical device wafer 100 in which a plurality of optical devices are arranged in a matrix on the surface of a sapphire substrate. The optical device wafer 100 is attached to a protective tape 12 mounted on an annular frame 11. A plurality are pasted.

  A temporary placement area 13a is set on the main support substrate 1a covering the upper surface of the apparatus housing 1, and a work piece is temporarily placed in the temporary placement area 13a, and a protective tape 12 is placed on the annular frame 11 via a protective tape 12. A temporary placement table 13 is provided for aligning the supported semiconductor wafer 10. The laser processing apparatus in the illustrated embodiment includes a semiconductor wafer 10 (hereinafter referred to as a semiconductor wafer) supported on an annular frame 11 accommodated in a cassette 9 placed on the cassette placement table 8 via a protective tape 12. The wafer 10 is carried out on the temporary table 13, the conveying means 15 for conveying the semiconductor wafer 10 carried on the temporary table 13 onto the chuck table 36, and laser processing on the chuck table 36. The cleaning means 16 for cleaning the semiconductor wafer 10 and the cleaning transport means 17 for transporting the semiconductor wafer 10 laser-processed on the chuck table 36 to the cleaning means 16 are provided. In addition, the laser processing apparatus in the illustrated embodiment includes a display unit 18 that displays an image captured by the imaging unit 6.

  Continuing the description with reference to FIG. 1, the laser processing apparatus in the illustrated embodiment includes a contour imaging means 19 disposed above the temporary placement table 14. The contour imaging means 19 can be constituted by a well-known CCD camera, images the semiconductor wafer 10 placed on the temporary placement table 14, and outputs the image information to the control means described later.

  The laser processing apparatus in the illustrated embodiment includes a protective film coating means 20 that covers the surface of the semiconductor wafer 10 conveyed on the chuck table 36. The protective film coating means 20 is disposed along the movement path of the chuck table 36, that is, along the guide rails 31, 31 of the chuck table mechanism 3, and the surface of the semiconductor wafer 10 that is a workpiece held by the chuck table 36. A spray nozzle 21 for spraying a liquid resin on the surface, and a resin supply means 22 for supplying the liquid resin to the spray nozzle 21 are provided. In the illustrated embodiment, the spray nozzle 21 is disposed at a workpiece transfer position where the chuck table 36 is located in FIG. The resin supply means 22 includes a tank 221 that stores a liquid resin, and a feed pump 223 disposed in the middle of a pipe 222 that connects the tank 221 and the spray nozzle 21. The liquid resin contained in the tank 221 is preferably a water-soluble resist such as PVA (Poly Vinyl Alcohol), PEG (Poly Ethylene Glycol), or PEO (Poly Ethylene Oxide).

  The laser processing apparatus in the illustrated embodiment includes a control means 25 as shown in FIG. The control means 25 is composed of a computer, and a central processing unit (CPU) 251 that performs arithmetic processing according to a control program, a read-only memory (ROM) 252 that stores a control program, and a readable / writable data that stores arithmetic results. A random access memory (RAM) 253, a counter 254, an input interface 255 and an output interface 256 are provided. Detection signals from the machining feed amount detection means 374, the index feed amount detection means 384, the maintenance means 6, the contour imaging means 19 and the like are input to the input interface 255 of the control means 25. From the output interface 256 of the control means 25, the pulse motor 372, the pulse motor 382, the pulse motor 432, the pulse motor 532, the laser beam irradiation means 52, the feed pump 223 (see FIG. 1) of the resin supply means 22, etc. Output a control signal.

The laser processing apparatus in the illustrated embodiment is configured as described above, and the operation thereof will be described below. In the following description, it is assumed that the wafer of the workpiece is the semiconductor wafer 10 shown in FIG.
The semiconductor wafer 10 accommodated in a predetermined position of the cassette 9 placed on the cassette placement table 8 is positioned at the carry-out position when the cassette placement table 8 moves up and down by a lifting means (not shown). Next, the unloading means 14 moves forward and backward, and the semiconductor wafer 10 positioned at the unloading position is unloaded onto the temporary placement table 13. Since the annular frame 11 is guided by the pair of guide rails 131 and 131 constituting the temporary placement table 13, the position of the semiconductor wafer 10 carried out to the temporary placement table 13 is restricted. . When the semiconductor wafer 10 is carried out to the predetermined position of the temporary placement table 13 in this way, the contour imaging means 19 images the semiconductor wafer 10. At this time, it is desirable to project a so-called backlight from the back side of the semiconductor wafer 10. Then, the contour recognition unit 19 sends the captured image information to the control unit 25. The control means 25 temporarily stores the image information sent from the contour imaging means 19 in a random access memory (RAM) 253. Then, the control means 25 recognizes the shape and position of the semiconductor wafer 10 based on the image information stored in the random access memory (RAM) 253, that is, the X coordinate value and the Y coordinate value of the outline of the semiconductor wafer 10, This image information is stored in a random access memory (RAM) 253. When the semiconductor wafer 10 is positioned at a predetermined position on the temporary table 13, the center P of the annular frame 11 is positioned so as to coincide with the center of the chuck table 36. Then, the X coordinate value and the Y coordinate value of the outline of the semiconductor wafer 10 are replaced with the coordinates with the center of the chuck table 36 as the origin.
When a plurality of optical device wafers 100 shown in FIG. 4 are attached to the protective tape 12 attached to the annular frame 11, the shape and position of each optical device wafer 100 are the X coordinate value, Y The coordinate value is stored in a random access memory (RAM) 253.

As described above, if image information related to the outline of the semiconductor wafer 10 is obtained and stored in the random access memory (RAM) 253, the semiconductor wafer 10 is positioned at the workpiece transfer position shown in FIG. The chuck table 36 is conveyed and sucked and held on the chuck table 36. Next, the chuck table 36 holding the semiconductor wafer 10 is moved to just below the alignment means 6 to perform alignment work, and alignment information is stored in a random access memory (RAM) 253. At this time, since the X coordinate value and the Y coordinate value of the outline of the semiconductor wafer 10 are stored in the random access memory (RAM) 253 as described above, an appropriate alignment region of the semiconductor wafer 10 is aligned based on this information. It can be positioned directly below the means 6. Therefore, the alignment operation can be performed quickly and accurately without causing an alignment error.
When a plurality of optical device wafers 100 shown in FIG. 4 are attached to the protective tape 12 attached to the annular frame 11, alignment is performed for each optical device wafer 100.

Next, the chuck table 36 holding the semiconductor wafer 10 is positioned at the workpiece transfer position shown in FIG. Then, a protective film coating step is performed in which a liquid resin is sprayed onto the surface of the semiconductor wafer 10 held on the chuck table 36 to spray the protective film.
In the protective film coating step, first, the processing feeding means 37 and the first indexing feeding means 38 shown in FIG. 2 are operated, and a predetermined position of the semiconductor wafer 10 held on the chuck table 36, for example, as shown in FIG. One end portion (left end portion in FIG. 5) of the orientation flat 103 representing the azimuth is positioned immediately below the spray nozzle 21 of the protective coating covering means 20. Next, the control unit 25 operates the feed pump 223 of the resin supply unit 22 and also operates the processing feed unit 37 to move the semiconductor wafer 10 at a predetermined speed in the direction indicated by the arrow X1. As a result, liquid resin is sprayed from the spray nozzle 21 onto the surface of the semiconductor wafer 10. Then, the control means 25 stops the operation of the processing feed means 37 and activates the first index feed means 38 when the right contour of the semiconductor wafer 10 in FIG. 5 reaches a position slightly exceeding the spray nozzle 21. The semiconductor wafer 10 is moved by a predetermined amount in the direction indicated by the arrow Y1 (for example, 10 mm when the width of the liquid resin sprayed from the spray nozzle 21 is 10 mm). Thus, when the semiconductor wafer 10 is moved by a predetermined amount in the direction indicated by the arrow Y1, the control means 25 stops the operation of the first index feeding means 38 and operates the processing feed means 37 to move the semiconductor wafer 10 to the arrow. Move at a predetermined speed in the direction indicated by X2. Then, the control means 25 stops the operation of the processing feed means 37 and operates the first index feed means 38 when the left contour of the semiconductor wafer 10 in FIG. The semiconductor wafer 10 is moved by a predetermined amount (for example, 10 mm) in the direction indicated by the arrow Y2. The control means 25 executes the above cycle until it reaches the end of the semiconductor wafer 10 opposite to the orientation flat 103. The movement of the semiconductor wafer 10 described above is recognized based on the image information sent from the contour imaging means 19 and stored in the random access memory (RAM) 253. The X coordinate value and the Y coordinate value of the contour of the semiconductor wafer 10 are stored. Are controlled based on detection signals from the machining feed amount detection means 374 and the index feed amount detection means 384. By performing the protective film coating process as described above, the protective film 104 is formed on the surface 10a of the semiconductor wafer 10 as shown in FIG. Since the protective coating 104 is formed by spraying, for example, a liquid resin having a width of 10 mm from the spray nozzle 21 as described above, the protective coating 104 is uniformly formed over the entire surface of the semiconductor wafer 10.

  If the protective film 104 is coated on the surface 10a which is the processed surface of the semiconductor wafer 10 by the protective film coating process described above, the laser beam along the street 102 passes through the protective film 104 on the surface of the semiconductor wafer 10 on which the protective film 104 is formed. A laser beam irradiation process for irradiating is performed. That is, the control unit 25 operates the processing feeding unit 37 to move the chuck table 36 holding the semiconductor wafer 10 to a processing region below the condenser 522 of the laser beam irradiation unit 52. Then, the processing feeding means 37 and the first indexing feeding means 38 are operated based on the alignment information described above, and a predetermined street 102 formed on the semiconductor wafer 10 held on the chuck table 36 is collected by the condenser. Positioned directly below 522. At this time, as shown in FIG. 7A, the semiconductor wafer 10 is positioned so that one end of the street 102 (the left end in FIG. 7A) is located directly below the condenser 522. Next, the chuck table 36, that is, the semiconductor wafer 10, is moved at a predetermined processing feed rate in the direction indicated by the arrow X1 in FIG. 7A while irradiating a pulse laser beam from the condenser 522 of the laser beam irradiation means 52. Then, as shown in FIG. 7B, when the other end of the street 102 (the right end in FIG. 7B) reaches a position directly below the condenser 522, the irradiation of the pulse laser beam is stopped and the chuck table 36 is stopped. That is, the movement of the semiconductor wafer 10 is stopped. In this laser beam irradiation step, the condensing point P of the pulse laser beam is adjusted to the vicinity of the surface of the street 102.

  By performing the laser beam irradiation process described above, a laser processing groove 105 is formed on the street 102 of the semiconductor wafer 10 as shown in FIG. At this time, even if the debris 106 is generated by the irradiation of the laser beam as shown in FIG. 8, the debris 106 is blocked by the protective film 104 and does not adhere to the device 101 and the bonding pad. Then, the laser beam irradiation process described above is performed on all the streets 101 of the semiconductor wafer 10. In the laser beam irradiation step described above, since the protective film 104 formed on the surface of the semiconductor wafer 10 is uniform over the entire surface, uniform laser processing can be performed.

In addition, the said laser beam irradiation process is performed on the following process conditions, for example.
Laser light source: YVO4 laser or YAG laser Wavelength: 355 nm
Repetition frequency: 20 kHz
Pulse width: 30 ns
Output: 3.0W
Condensing spot diameter: φ10μm
Processing feed rate: 100 mm / sec

  If the laser beam irradiation process described above is performed along all the streets 101 of the semiconductor wafer 10, the chuck table 36 holding the processed semiconductor wafer 10 is moved to a position facing the cleaning means 16. Here, the suction holding of the semiconductor wafer 10 is released. Then, the processed semiconductor wafer 10 is transported to the cleaning means 16 by the cleaning transport means 17 and cleaned with cleaning water. By this cleaning, the protective film 104 coated on the surface 10a of the semiconductor wafer 10 is formed of the water-soluble resin as described above. Therefore, the protective film 104 can be easily washed out and generated during laser processing. Debris 106 is also removed.

  When the cleaning process is completed as described above, the processed semiconductor wafer 10 is transferred onto the chuck table 36 by the cleaning transfer means 17. The chuck table 36 holding the semiconductor wafer is positioned at the workpiece transfer position shown in FIG. Next, the processed semiconductor wafer 10 is transported to the temporary placement table 13 by the transport means 15. The processed semiconductor wafer 10 conveyed to the temporary placement table 13 is stored in a predetermined position of the cassette 9 by the unloading means 14.

  In the above-described embodiment, the example in which the alignment work is performed before the protective film coating process is performed has been described. However, the alignment work may be performed after the protective film coating process is performed. In this case, in addition to a normal imaging device (CCD) that images the alignment means 6 with visible light, infrared illumination means for irradiating infrared rays, an optical system for capturing infrared rays emitted by the infrared illumination means, and the optical system An imaging device (infrared CCD) or the like that outputs an electrical signal corresponding to the infrared rays captured by the sensor, and after performing the protective coating process, passes through the protective coating and images the wafer to perform the alignment operation.

The perspective view of the laser processing apparatus comprised according to this invention. The principal part perspective view of the laser processing apparatus shown in FIG. FIG. 2 is a perspective view showing a state in which a semiconductor wafer which is an embodiment of a wafer processed by the laser processing apparatus shown in FIG. 1 is attached to a protective tape attached to an annular frame. The perspective view which shows the state by which the optical device wafer which is other embodiment of the wafer processed with the laser processing apparatus shown in FIG. 1 was affixed on the protective tape with which the cyclic | annular flame | frame was mounted | worn. Explanatory drawing of the protective film coating process in the laser processing method of the wafer by this invention. The principal part expanded sectional view of the semiconductor wafer as a workpiece by which the protective film was coat | covered by the protective film formation process. Explanatory drawing which shows the laser beam irradiation process in the laser processing method of the wafer by this invention. The principal part expanded sectional view of the semiconductor wafer laser-processed by the laser beam irradiation process shown in FIG. Explanatory drawing which shows the coating method of the conventional protective film.

Explanation of symbols

1: Device housing 2: Stationary base 3: Chuck table mechanism 32: First slide block 33: Second slide block 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 feed means 5: Laser beam irradiation unit 52: Laser beam irradiation means 6: Alignment means 8: Cassette table 9: Cassette 10: Semiconductor wafer 100: Optical device wafer 101: Device 102: Street 103: Orientation flat 104: Protective coating 105: Laser processing groove 106: Debris 11: Annular frame 12: Protective tape 13: Temporary table 14: Unloading means 1 : Conveying means 16: cleaning means 17: cleaning conveying means 18: display means 19: contour imaging means 20: protective film coating means 21: spray nozzle 22: resin supply means 25: control means

Claims (3)

A wafer laser processing method for performing laser processing along a lattice-shaped street partitioning a device having a plurality of devices formed in a matrix on the surface,
A protective coating coating step of spraying a liquid resin on the processed surface of the wafer by spraying to coat the protective coating;
A laser beam irradiation step of irradiating a laser beam along the street through the protective coating on the processed surface of the wafer on which the protective coating is formed,
A wafer laser processing method characterized by the above.   The wafer laser processing method according to claim 1, wherein the liquid resin is a water-soluble resin. A chuck table for holding a workpiece, a laser beam irradiation means for irradiating a workpiece held on the chuck table with a laser beam, and a processing feed means for relatively processing and feeding the chuck table and the laser beam irradiation means In a laser processing apparatus comprising:
A spray nozzle that is disposed along a movement path of the chuck table and sprays a liquid resin onto a surface of a workpiece held by the chuck table;
A resin supply means for supplying a liquid resin to the spray nozzle,
Laser processing equipment characterized by that.

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