JP2014116486A - Laser processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser processing device that includes a chuck table capable of suppressing costs when many kinds of chuck tables are prepared according to workpieces.SOLUTION: A laser processing device 2 which cuts a workpiece 11 along a plurality of crossing predetermined cutting lines includes a chuck table 28 which holds the plate-like workpiece 11 and laser beam irradiation means 36 for the plate-like workpiece 11. The chuck table 28 includes a chuck table body part having a workpiece holding part for holding the workpiece 11 and an outer peripheral part surrounding the workpiece 11, and a base part 29 which supports the chuck table body part on its support surface and has a suction path 47 formed having one end linked to the support surface and the other end connected to a suction source 54. The chuck table body part is mounted detachably on the base part 29, and the chuck table body part having the workpiece holding part corresponding to the shape of the workpiece is properly selected and mounted on the base part 29.

Description

  The present invention relates to a laser processing apparatus for irradiating a workpiece with a laser beam and cutting the workpiece into a plurality of chips.

  In a semiconductor device manufacturing process, a plurality of regions are defined by planned cutting lines called streets formed in a lattice shape on the surface of a semiconductor wafer having a substantially disk shape, and devices such as IC and LSI are defined in the partitioned regions. Form. Individual semiconductor devices are manufactured by dicing the semiconductor wafer along the streets.

  In recent years, as a method of dividing a plate-like workpiece such as a semiconductor wafer, a laser processing groove is formed in the workpiece by irradiating a pulse laser beam along a street formed on the workpiece, and this laser processing. A method of cleaving a workpiece along a groove by a mechanical braking device has been proposed (see, for example, Japanese Patent Laid-Open No. 10-305421).

  However, since the device is heated when the semiconductor wafer is irradiated with a laser beam, there is a problem that the quality of the device is deteriorated. Therefore, as a laser processing method for preventing the workpiece from being heated by irradiating the laser beam, a liquid column is formed by injecting a high-pressure liquid onto the workpiece, and the liquid column is transmitted (guided). There has been proposed a laser processing apparatus (water jet laser processing apparatus) that performs desired processing by irradiating a workpiece with a laser beam that has been subjected to light (for example, Japanese Patent Publication No. 2-1621, JP 2001- No. 321977 and Japanese Patent Application Laid-Open No. 2011-41962).

  In these laser processing apparatuses, since the condensed laser beam is guided to the workpiece through the thread-like liquid column, laser processing can be performed regardless of the focal position of the condensing lens. Furthermore, since the heat generated during laser processing is cooled by the liquid, there is an advantage that it is possible to prevent deterioration of the quality of the workpiece due to heat.

  In water jet laser processing, as the liquid column that collides with the processing point scatters on the surface of the workpiece, debris generated in the processing included in the liquid constituting the liquid column adheres to the surface of the workpiece. There is a problem, and in order to solve this problem, the present applicant has applied for a chuck table that holds a workpiece in a state where a predetermined space is provided below a cutting line (Japanese Patent Application No. 2011-270112). .

Japanese Patent Laid-Open No. 10-305421 Japanese Patent Publication No.2-1621 Japanese Patent Laid-Open No. 2001-321977 JP 2011-41962 A

  In such a chuck table, it is necessary to change the size of the workpiece holding part according to the size of the chip or the size of the workpiece. Therefore, when machining various types of devices, It is necessary to prepare a chuck table.

  Since the chuck table requires accuracy and requires a considerable cost for production, there is a problem that it is more expensive than fixing using an adhesive tape and an annular frame used in a laser processing apparatus or a dicing apparatus.

  Also, if you accidentally machine the holding surface of the work piece holding part and damage the chuck table, you must create a chuck table with exactly the same shape. There was a problem that it was expensive.

  The present invention has been made in view of the above points, and an object of the present invention is to prepare various types of chuck tables according to the outer diameter size of the workpiece, the chip size, and the number of lines to be cut. At the same time, it is to provide a laser processing apparatus including a chuck table capable of suppressing cost.

  According to the present invention, there is provided a laser processing apparatus that cuts a plate-like workpiece having a plurality of intersecting scheduled cutting lines on the surface along the scheduled cutting line, and holds the plate-like workpiece. A chuck table; and a laser beam irradiation means for irradiating a plate-like workpiece held by the chuck table with a laser beam. The laser beam irradiation means includes a laser beam generation means and the laser beam generation means. A condensing lens that condenses the laser beam generated from the means, and a liquid that forms a liquid column that guides the laser beam condensed by the condensing lens by ejecting the liquid onto the plate-like workpiece The chuck table includes a workpiece holding portion that holds the workpiece, and an outer peripheral portion that surrounds the workpiece held by the workpiece holding portion. A chuck table main body portion, a base portion on which a first suction path is formed in which the chuck table main body portion is supported by a support surface, one end communicates with the support surface, and the other end is connected to a suction source; The workpiece holding portion of the chuck table main body includes a plurality of liquid column escape grooves that divide a plurality of chip holding regions respectively corresponding to the scheduled cutting lines of the plate-like workpiece, A suction hole formed in the chip holding region, and a second suction path connecting the suction hole and the first suction path, and the chuck table body is detachably mounted on the base part. There is provided a laser processing apparatus characterized in that the chuck table main body portion on which a workpiece holding portion corresponding to the shape of the workpiece is formed can be appropriately selected and mounted on the base portion.

  According to the present invention, the chuck table to be used is configured by detachably attaching the chuck table main body portion having the workpiece holding portion to the base portion, so that it is integrally formed according to the outer diameter size of the workpiece. Since only the chuck table main body portion needs to be replaced rather than replacing the chuck table, the chuck table can be replaced at low cost.

  In addition, depending on the device, when preparing various types of chuck tables according to the workpiece outer diameter size, chip size, and the number of lines to be cut, it is only necessary to prepare a large number of chuck table main bodies, so that the cost Can be suppressed.

1 is a perspective view of a laser processing apparatus according to an embodiment of the present invention. It is a block diagram of a laser beam generation unit. It is a perspective view of the chuck table concerning an embodiment of the present invention. It is sectional drawing of the chuck table shown in FIG. FIG. 4 is an exploded perspective view of the chuck table shown in FIG. 3. It is a longitudinal cross-sectional view of the chuck table holding the processing head and the plate-like workpiece during laser processing. It is sectional drawing which shows a mode that a chuck | zipper table main-body part is replaced | exchanged.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, an external perspective view of a laser processing apparatus according to an embodiment of the present invention is shown. The laser processing apparatus 2 includes a first slide block 6 mounted on a stationary base 4 so as to be movable in the X-axis direction.

  The first slide block 6 is moved in the machining feed direction, that is, the X-axis direction along the pair of guide rails 14 by the machining feed mechanism 12 including the ball screw 8 and the pulse motor 10.

  A second slide block 16 is mounted on the first slide block 6 so as to be movable in the Y-axis direction. That is, the second slide block 16 is moved along the pair of guide rails 24 by the index feed mechanism 22 including the ball screw 18 and the pulse motor 20 in the index feed direction, that is, the Y-axis direction.

  A chuck table 28 is mounted on the second slide block 16 via a cylindrical support member 26, and the chuck table 28 can be moved in the X-axis direction and the Y-axis direction by the machining feed mechanism 12 and the index feed mechanism 22. At the same time, it is rotated by a motor accommodated in the cylindrical support member 26.

  Reference numeral 32 denotes a water cover. A bellows (not shown) is connected to the water cover 32 to protect the processing feed mechanism 12 and the index feed mechanism 22 from liquids such as water.

  A column 34 is erected on the stationary base 4, and a laser beam irradiation mechanism (laser beam irradiation means) 36 is attached to the column 34. The laser beam irradiation mechanism 36 includes a laser beam generation unit 38 housed in the casing 40 and a processing head 42 attached to the tip of the casing 40. An imaging unit 52 is attached to the front end of the casing 40 in alignment with the machining head 42 in the X-axis direction.

  As shown in FIG. 2, the laser beam generating unit 38 includes a laser oscillator 44 that oscillates a YAG laser or a YVO4 laser, a repetition frequency setting means 46, a pulse width adjusting means 48, and a power adjusting means 50. . Although not particularly shown, the laser oscillator 44 has a Brewster window, and the laser beam emitted from the laser oscillator 44 is a linearly polarized laser beam.

  The liquid supply source 84 stores a liquid such as pure water. The liquid pressurized to a predetermined pressure by the pump 82 is supplied to the processing head 42, and the liquid column is supplied to the chuck table 28 from the injection nozzle of the liquid injection means. Sprayed onto the workpiece being held.

  The laser beam adjusted to a predetermined power by the power adjusting means 50 of the laser beam generating unit 38 is introduced into the machining head 42, condensed by the condenser lens at the injection nozzle, and guided to the liquid column. At the same time, the workpiece is irradiated.

  Next, the detailed structure of the chuck table 28 according to the embodiment of the present invention will be described with reference to FIGS. The chuck table 28 includes a base portion 29 formed of a metal such as SUS and a circular chuck table main body portion 31 formed of a metal such as SUS that is detachably fitted to the base portion 29. Is done.

  As best shown in FIG. 5, the base portion 29 has a circular fitting recess 56, and the chuck table main body 31 is fitted into the fitting recess 56, and the bottom surface of the fitting recess 56 ( It is supported by a support surface 56a (see FIG. 4).

  A suction recess 58 having a predetermined depth is formed at the bottom of the fitting recess 56. A first suction path 47 connected to the negative pressure suction source 54 is formed substantially at the center of the suction recess 58. A plurality of screw holes 51 are formed in the bottom surface 56 a of the fitting recess 56.

  The chuck table main body portion 31 includes a workpiece holding portion 35 that holds a workpiece and an outer peripheral portion 37 that surrounds the workpiece held by the workpiece holding portion 35. The workpiece holding part 35 has a plurality of chip holding regions 39 corresponding to devices of a workpiece such as a ceramic substrate, and suction holes 41 are formed in each chip holding region 39. These suction holes 41 communicate with a suction recess 58 formed in the base portion 29 through a second suction path 49.

  The workpiece holder 35 of the chuck table main body 31 further has a liquid column escape groove 43 that defines a plurality of chip holding regions 39 corresponding to the scheduled cutting line 13 of the workpiece 11. The depth of the liquid column escape groove 43 is preferably 3 mm or more.

  A liquid reservoir 45 is formed on the outer peripheral portion 37 surrounding the workpiece holder 35 of the chuck table main body 31 so as to surround the workpiece holder 35 adjacent to the workpiece holder 35. . The liquid reservoir 45 communicates with both ends of a liquid column escape groove 43 formed in a lattice shape.

  The bottom of the liquid column escape groove 43 is inclined so as to become lower from the workpiece holding portion 35 toward the outside of the chuck table main body portion 31. A plurality of holes 53 into which the screws 33 are inserted are formed in the outer peripheral portion 37 of the chuck table main body portion 31.

  To assemble the chuck table 28, the chuck table main body 31 is fitted into the fitting groove 56 of the base 29 and supported by the support surface 56a. The chuck table main body 31 is fixed to the base 29 by screwing and tightening the plurality of screws 33 into the screw holes 51 of the base 29 through the holes 53.

  In a state where the chuck table main body 31 is fixed to the base 29, the upper surface of the outer peripheral portion 37 of the chuck table main body 31 and the upper surface of the base 29 are flush with each other as shown in FIGS. It is formed.

  When laser processing is performed on the workpiece 11 by the laser processing apparatus 2 of the present invention, as shown in FIG. 6, the workpiece 11 is cut so that each scheduled cutting line 13 corresponds to the liquid column escape groove 43. The workpiece 11 is positioned and mounted on the chuck table main body 31. For this positioning, for example, a positioning pin or the like provided on the chuck table main body 31 is used.

  Next, a detailed structure of the processing head 42 and a method of cutting the workpiece 11 using the laser processing apparatus 2 will be described with reference to FIG. The pulsed laser beam 55 adjusted to a predetermined power by the power adjusting means 50 of the laser beam generating unit 38 enters the processing head 42 from a beam inlet 58 formed in the housing 56 of the processing head 42 as shown in FIG. be introduced.

  In the housing 56, a mirror 60 for reflecting the laser beam and a condenser lens 62 for condensing the laser beam are disposed. A liquid chamber housing 68 that defines a liquid chamber 66 of the liquid ejecting means 64 integrally with the housing 56 is formed. The liquid chamber housing 68 includes a cylindrical side wall 70, and an upper wall 72 and a lower wall 74 that close the upper and lower surfaces of the side wall 70, respectively.

  A transparent window 78 is disposed on the upper wall 72 constituting the liquid chamber housing 68. An injection nozzle 80 is formed at the center of the lower wall 74 constituting the liquid chamber housing 68. A condensing point of the laser beam 55 condensed by the condensing lens 62 is positioned at the ejection port 80a which is the lower end of the ejection nozzle 80.

  The cylindrical side wall 72 has a liquid inlet 76 communicating with the liquid chamber 66, and the liquid inlet 76 is connected to a liquid supply source 84 via a pump 82. The liquid supply source 84 stores a liquid such as pure water, and the liquid pressurized to a predetermined pressure by the pump 82 is supplied into the liquid chamber 66 through the liquid inlet 76. When the high-pressure liquid is supplied into the liquid chamber 66, the high-pressure liquid is ejected from the ejection port 80 a of the ejection nozzle 80 to form the liquid column 86.

  A block 88 is attached to the lower end portion of the liquid chamber housing 68. A through hole 89 is formed at the center of the block 88, and a pipe 90 is press-fitted into the through hole 89. The pipe 90 and the injection nozzle 80 are aligned, and the liquid column 86 formed by being injected from the injection nozzle 80 is positioned so as to pass through the pipe 90.

  Hereinafter, the operation of the laser processing apparatus 2 configured as described above will be described. The laser beam 55 adjusted to a predetermined power by the power adjusting means 50 of the laser beam generating unit 38 is introduced into the processing head 42 from the beam introduction port 58 of the processing head 42, reflected by the mirror 60, and reflected by the condenser lens 62. The light is condensed on the ejection port 80 a of the ejection nozzle 80 formed in the liquid chamber housing 68 of the liquid ejection means 64.

  On the other hand, a high-pressure liquid such as pure water pressurized to high pressure by the pump 82 is supplied into the liquid chamber 66 from the liquid inlet 76 formed in the liquid chamber housing 68 of the liquid ejecting means 64, and The liquid column 86 is formed by being sprayed from the spray nozzle 80 formed on the lower wall 74, and the liquid column 86 guides the laser beam 55.

  The liquid column 86 passes through the pipe 90 press-fitted into the through-hole 89 of the block 88 and collides with the processing point of the workpiece 11 and scatters. The laser beam 55 condensed by the condenser lens 62 is guided (guided) to a liquid column 86 passing through the pipe 90, and the beam diameter is not widened but irradiated to a processing point and penetrates the workpiece 11. The laser processing groove 17 to be formed is formed. The liquid forming the liquid column 86 flows out into the liquid column escape groove 43 which is a space below the workpiece 11 through the laser machining groove 17 penetrating the workpiece 11.

  Debris (machining waste) is generated along with the laser processing, but the generated debris 19 is taken into the liquid 85 forming the liquid column 86 and flows out into the liquid column escape groove 43. According to the present embodiment, since the liquid 85 in which the liquid column 86 is formed is not scattered on the surface of the workpiece 11, the debris 19 contained in the liquid 85 may adhere to the surface of the workpiece 11. Is prevented.

  Further, the liquid 85 forming the liquid column 86 flows out into the liquid column escape groove 43 which is a space below the workpiece 11, so that the debris 19 adheres to the cut side surface of the workpiece 11 and so-called recast occurs. Therefore, even thicker workpieces can be cut.

  In addition, the laser processing conditions of the workpiece 11 by the laser processing apparatus 2 of this embodiment are as follows, for example.

Light source: LD excitation Q switch Nd: YVO4 pulse laser Wavelength: 532 nm (second harmonic of YVO4 laser)
Average output: 6.6W
Repetition frequency: 40 kHz
Fluid pressure: 20 MPa

  The chuck table main body 31 having the liquid column escape groove 43 and the suction hole 41 corresponding to each chip corresponding to the planned cutting line 13 of the workpiece 11 is the outer diameter size, chip size, and cutting schedule of the workpiece 11. It is necessary to change according to the number of lines 13.

  In the present embodiment, the chuck table 28 is composed of a base portion 29 and a chuck table main body portion 31 fitted into the fitting recess 56 of the base portion 29. Therefore, as shown in FIG. When the workpiece 11 having a large number of cutting lines 13 is sucked and held, the chuck table main body 31 is removed and the chuck table main body 31A is fixed to the base 29 of the chuck table 28A.

  Thus, since the chuck table main body 31 is configured to be detachable from the base 29, the cost can be reduced because only the chuck table main body 31 needs to be replaced rather than replacing the integrally formed chuck table. That's it.

  Further, when preparing various types of chuck tables according to the outer diameter size of the workpiece, the chip size, and the number of lines to be cut, it is only necessary to prepare a plurality of types of chuck table main body portions 31, thereby reducing costs. be able to.

  In the embodiment described above, the workpiece 11 is described as being a rectangular ceramic substrate or the like. However, the workpiece is not limited to a rectangular shape, and a semiconductor wafer or an optical device in which the workpiece is circular. The principle of the present invention can be applied to a wafer or the like.

  When the workpiece is circular, it is necessary to change the design of the workpiece holding portion 35 of the chuck table main body 31 to a circle, and accordingly, the liquid reservoir 45 also has a circular workpiece holding portion 35. It needs to be a circular shape that surrounds.

2 Laser processing apparatus 11 Work piece 28 Chuck table 29 Base part 31 Chuck table main body part 35 Work piece holding part 37 Outer peripheral part 39 Chip holding area 41 Suction hole 43 Liquid column escape groove 47 First suction path 49 Second suction Path 56 fitting recess 58 suction recess

Claims (1)

A laser processing apparatus for cutting a plate-shaped workpiece having a plurality of intersecting scheduled cutting lines set on the surface along the scheduled cutting line,
A chuck table for holding a plate-shaped workpiece;
A laser beam irradiation means for irradiating a laser beam to a plate-like workpiece held on the chuck table,
The laser beam irradiation means
Laser beam generating means;
A condensing lens for condensing the laser beam generated from the laser beam generating means, and a liquid column for guiding the laser beam condensed by the condensing lens by injecting liquid onto a plate-like workpiece A liquid ejecting means for forming a machining head,
The chuck table has a workpiece holding portion for holding a workpiece, and a chuck table main body having an outer peripheral portion surrounding the workpiece held by the workpiece holding portion,
The chuck table body is supported by a support surface, and a base portion is formed with a first suction path in which one end communicates with the support surface and the other end is connected to a suction source.
The workpiece holding portion of the chuck table main body includes a plurality of liquid column escape grooves that divide a plurality of chip holding regions respectively corresponding to the scheduled cutting lines of the plate-like workpiece, and the chip holding regions. Each of the formed suction holes, and a second suction path connecting the suction holes and the first suction path,
The chuck table main body is detachably mounted on the base, and the chuck table main body formed with a workpiece holding portion according to the shape of the workpiece is appropriately selected and mounted on the base. Laser processing equipment that is possible.

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