JP2012002604A - Height position measuring device for workpiece supported on chuck table and laser processing machine - Google Patents

Abstract

A height position measuring device and a laser beam machine for measuring the upper surface position of a workpiece are provided.
A light branching unit that guides light from a light source to a first path and guides reflected light to a second path, and a collimation lens that forms the light guided to the first path into parallel light. An objective lens that guides the light formed in the light to the workpiece, and a cylinder made of a transparent body that is disposed between the collimation lens and the objective lens, has a reflection mirror formed on the end surface on the objective lens side, and extends the optical path length -Shaped reference optical path length setting member, reflected light reflected by the reflecting mirror and guided to the second path from the first light branching means, and reflected by the work piece to the second path from the first light branching means A diffraction grating that diffracts the interference with the reflected light guided to the surface, and an upper surface of the workpiece from the surface of the chuck table based on a detection signal from an image sensor that detects light intensity in a predetermined wavelength region of the diffracted reflected light. Find the distance to And a control unit.
[Selection] Figure 2

Description

  The present invention relates to a height position measuring device and a laser processing machine for measuring the height of a workpiece such as a semiconductor wafer held on a chuck table equipped on a processing machine such as a laser processing machine.

  In the semiconductor device manufacturing process, a plurality of regions are partitioned by dividing lines called streets arranged in a lattice pattern on the surface of a substantially wafer-shaped semiconductor wafer, and devices such as ICs, LSIs, etc. are partitioned in the partitioned regions. Form. Then, the semiconductor wafer is cut along the streets to divide the region in which the device is formed to manufacture individual semiconductor devices.

  In the optical device manufacturing process, light emitting diodes are formed in a plurality of regions partitioned by a plurality of streets formed by laminating an optical device layer made of a gallium nitride compound semiconductor on the surface of a sapphire substrate or silicon carbide substrate. Then, an optical device such as a laser diode is formed to constitute an optical device wafer. Then, the optical device wafer is cut along the streets to divide the region where the optical device is formed to manufacture individual optical devices.

  As a method of dividing a wafer such as the above-described semiconductor wafer or optical device wafer along the street, a pulsed laser beam having transparency to the wafer is used, and the focused laser beam is aligned with the inside of the region to be divided. Laser processing methods for irradiation have been attempted. The dividing method using this laser processing method is to irradiate a pulse laser beam having a wavelength having transparency to the wafer from one side of the wafer to the inside, and irradiate the wafer along the street. The altered layer is formed continuously, and the wafer is divided by applying an external force along the street whose strength is reduced by the formation of the altered layer. (For example, refer to Patent Document 1.) When the altered layer is formed inside along the street formed on the workpiece as described above, a laser beam condensing point is formed at a predetermined depth position from the upper surface of the workpiece. It is important to position.

  In addition, as a method of dividing a wafer such as a semiconductor wafer or an optical device wafer, a laser processing groove is formed by irradiating a pulsed laser beam having a wavelength having an absorptivity with respect to the wafer along a street formed on the wafer. A method of cleaving with a mechanical braking device along the laser processed groove has been proposed. (For example, refer to Patent Document 2.) Even when the laser processing groove is formed along the street formed on the wafer as described above, it is important to position the condensing point of the laser beam at a predetermined height position of the wafer. .

  However, since plate-like workpieces such as wafers have undulations and their thickness varies, it is difficult to perform uniform laser processing. That is, when forming an altered layer along the street inside the wafer, if the wafer thickness varies, the altered layer is uniformly formed at a predetermined depth position due to the refractive index when irradiating a laser beam. I can't. Further, even when the laser processing groove is formed along the street formed on the wafer, if the thickness varies, the laser processing groove having a uniform depth cannot be formed.

  In order to solve the above-described problem, a height position measuring device that can reliably measure the upper surface height of a workpiece such as a wafer held on a chuck table is disclosed in Patent Document 3 below. The measuring device disclosed in Patent Document 3 below uses the fact that white light that has passed through a chromatic aberration lens has a focal length that differs depending on the wavelength, and determines the focal length by specifying the wavelength by the reflected light. The height position of the workpiece held on the table can be accurately measured.

Japanese Patent No. 3408805 JP-A-10-305420 JP 2008-170366 A

  Thus, when white light is condensed by the chromatic aberration lens, a condensing point corresponding to each wavelength is positioned on the optical axis, but as the wavelength becomes longer, it is positioned on the inner side (optical axis side) of the condensing lens. In particular, since the NA value is small, there is a problem in that the focal point is blurred and an accurate surface height position cannot be detected.

  The present invention has been made in view of the above-mentioned facts, and its main technical problem is that it can accurately measure the height of a workpiece such as a semiconductor wafer or an optical device wafer held on a chuck table. The present invention is to provide a laser processing machine equipped with a height position measuring device and a height position measuring device.

In order to solve the main technical problem, according to the present invention, in the workpiece height position measuring device for detecting the position of the workpiece held on the holding surface of the chuck table,
A light emitting source that emits light having a predetermined wavelength region;
Light branching means for guiding the light from the light emitting source to the first path and for guiding the reflected light that travels backward through the first path to the second path;
A collimation lens that forms light guided to the first path into parallel light;
An objective lens that guides light formed into parallel light by the collimation lens to a workpiece held by the chuck table;
A light passage hole disposed between the collimation lens and the objective lens for allowing light to pass therethrough has an annular light receiving surface on the end surface on the collimation lens side and an annular reflection mirror on the end surface on the objective lens side A cylindrical reference optical path length setting member made of a transparent body having a refractive index larger than air and substantially extending the optical path length,
Reflected light reflected by the reflecting mirror of the reference optical path length setting member and guided back to the second path from the light branching means by going back the reference optical path length setting member, the collimation lens, and the first path; Reflected by the workpiece held on the chuck table, the objective lens, the light passage hole of the reference optical path length setting member, the collimation lens, and the first path are moved backward from the light branching means to the second light path. A diffraction grating that diffracts interference with reflected light guided along the path of
An image sensor for detecting light intensity in a predetermined wavelength range of reflected light diffracted by the diffraction grating;
A spectral interference waveform is obtained based on a detection signal from the image sensor, a waveform analysis is performed based on the spectral interference waveform and a theoretical waveform function, and an annular reflection from the annular light receiving surface of the reference optical path length setting member. The optical path length difference between the reference optical path length to the mirror and the optical path length from the light incident portion of the light passage hole of the reference optical path length setting member to the workpiece held on the chuck table is obtained. Control means for obtaining a distance from the surface of the chuck table to the upper surface of the workpiece held on the chuck table based on
An apparatus for measuring a workpiece held on a chuck table is provided.

Further, according to the present invention, a chuck table having a holding surface for holding a workpiece, laser beam irradiation means for irradiating a workpiece held on the holding surface of the chuck table with a laser beam, the chuck table, and the chuck table A processing feed means for relatively moving the laser beam irradiation means in the processing feed direction; and a height position measuring device for detecting the position of the workpiece held on the holding surface of the chuck table, the laser beam irradiation. The means includes a laser beam oscillator that oscillates a laser beam, and a laser beam collector that condenses the laser beam oscillated from the laser beam oscillator and irradiates the workpiece held on the holding surface of the chuck table. In
The height position measuring device includes a light emitting source that emits light having a predetermined wavelength region;
Light branching means for guiding the light from the light emitting source to the first path and for guiding the reflected light that travels backward through the first path to the second path;
A collimation lens that forms light guided to the first path into parallel light;
An objective lens that guides light formed into parallel light by the collimation lens to a workpiece held by the chuck table;
A light passage hole disposed between the collimation lens and the objective lens for allowing light to pass therethrough has an annular light receiving surface on the end surface on the collimation lens side and an annular reflection mirror on the end surface on the objective lens side A cylindrical reference optical path length setting member made of a transparent body having a refractive index larger than air and substantially extending the optical path length,
Reflected light reflected by the reflecting mirror of the reference optical path length setting member and guided back to the second path from the light branching means by going back the reference optical path length setting member, the collimation lens, and the first path; The light beam is reflected by the workpiece held on the chuck table and travels backward through the objective lens, the condenser lens, the light passage hole of the reference optical path length setting member, the collimation lens, and the first path. A diffraction grating for diffracting interference with reflected light guided from the means to the second path;
An image sensor for detecting light intensity in a predetermined wavelength range of reflected light diffracted by the diffraction grating;
A spectral interference waveform is obtained based on a detection signal from the image sensor, a waveform analysis is executed based on the spectral interference waveform and a theoretical waveform function, and an annular reflection mirror is formed from the annular light receiving surface of the reference optical path length setting member The optical path length difference between the reference optical path length up to and the optical path length from the light incident portion of the light passage hole of the reference optical path length setting member to the workpiece held on the chuck table is determined based on the optical path length difference. And a control means for obtaining a distance from the surface of the chuck table to the upper surface of the workpiece held on the chuck table,
The detection light irradiation means is disposed adjacent to the condenser;
A laser beam machine characterized by the above is provided.

Condensing point position adjusting means for moving the condenser of the laser beam irradiating means in a condensing point position adjusting direction perpendicular to the holding surface of the chuck table is provided, and the control means receives light of a reference optical path length setting member. The focal point is based on the optical path length difference between the reference optical path length from the surface to the annular reflecting mirror and the optical path length from the light incident portion of the light passage hole of the reference optical path length setting member to the workpiece held on the chuck table. Control the position adjusting means.
The said detection light irradiation means is each arrange | positioned at the process feed direction both sides of a collector.

Further, according to the present invention, a chuck table having a holding surface for holding a workpiece, laser beam irradiation means for irradiating the workpiece held on the chuck table with a laser beam, and a workpiece held on the chuck table. In a laser processing machine comprising a measuring device for detecting the height position of a workpiece,
The measuring device includes a light emitting source that emits light having a predetermined wavelength region;
Light branching means for guiding the light from the light emitting source to the first path and for guiding the reflected light that travels backward through the first path to the second path;
A collimation lens that forms light guided to the first path into parallel light;
An objective lens that guides light formed into parallel light by the collimation lens to a workpiece held by the chuck table;
A light passage hole disposed between the collimation lens and the objective lens for allowing light to pass therethrough has an annular light receiving surface on the end surface on the collimation lens side and an annular reflection mirror on the end surface on the objective lens side A cylindrical reference optical path length setting member made of a transparent body having a refractive index larger than air and substantially extending the optical path length,
Reflected light reflected by the reflecting mirror of the reference optical path length setting member and guided back to the second path from the light branching means by going back the reference optical path length setting member, the collimation lens, and the first path; Reflected by the workpiece held on the chuck table, the objective lens, the light passage hole of the reference optical path length setting member, the collimation lens, and the first path are moved backward from the light branching means to the second light path. A diffraction grating that diffracts interference with reflected light guided along the path of
An image sensor for detecting light intensity in a predetermined wavelength range of reflected light diffracted by the diffraction grating;
A spectral interference waveform is obtained based on a detection signal from the image sensor, a waveform analysis is performed based on the spectral interference waveform and a theoretical waveform function, and from the light receiving surface of the reference optical path length setting member to the annular reflection mirror The optical path length difference between the reference optical path length of the optical path length and the optical path length from the light incident portion of the light passage hole of the reference optical path length setting member to the workpiece held on the chuck table is determined based on the optical path length difference. Control means for obtaining a distance from the surface of the chuck table to the upper surface of the workpiece held on the chuck table,
The laser beam irradiation unit includes a laser beam oscillation unit that oscillates a laser beam, a laser beam oscillated from the laser beam oscillation unit that is disposed between the reference optical path length setting member and the objective lens, and changes the direction of the laser beam toward the objective lens. A dichroic mirror
A laser beam machine characterized by the above is provided.

The parallel light formed by the collimation lens disposed between the reference optical path length setting member and the dichroic mirror is condensed, and the focal point is positioned on the objective lens to generate the light from the objective lens as pseudo-parallel light. A condensing lens.
Further, the laser beam irradiating means includes focusing point position adjusting means for moving the objective lens in the focusing point position adjusting direction perpendicular to the holding surface of the chuck table, and the control means is a reference optical path length setting member. Condensation based on the optical path length difference between the reference optical path length from the light receiving surface to the annular reflecting mirror and the optical path length from the light entrance hole of the light passage hole of the reference optical path length setting member to the workpiece held on the chuck table Control the point position adjusting means.

The apparatus for measuring the height position of the workpiece held on the chuck table according to the present invention is configured as described above, obtains the spectral interference waveform based on the detection signal from the image sensor, and obtains the spectral interference waveform and the theoretical waveform. Waveform analysis is performed based on the function, and the chuck is held on the chuck table from the reference optical path length from the light receiving surface of the reference optical path length setting member to the annular reflecting mirror and the light entrance hole of the light passage hole of the reference optical path length setting member The optical path length difference from the optical path length to the workpiece is obtained, and the distance from the surface of the chuck table to the upper surface of the workpiece held on the chuck table is obtained based on the optical path length difference. It is possible to accurately measure the upper surface position of the workpiece.
Further, since the laser processing machine according to the present invention is equipped with the above-described height position measuring device, it is possible to accurately perform laser processing at a predetermined position based on the upper surface position of the workpiece held on the chuck table. it can.

The perspective view of the laser processing machine comprised according to this invention. FIG. 2 is a block configuration diagram of a laser beam irradiation means and a height position measuring device installed in the laser processing machine shown in FIG. Explanatory drawing which shows the spectral interference waveform calculated | required by the control means which comprises the height position measuring apparatus shown in FIG. Explanatory drawing which shows the optical path length difference to the surface of the workpiece calculated | required by the control means which comprises the height position measuring apparatus shown in FIG. The optical path length difference up to the surface of the workpiece and the optical path length difference up to the surface of the workpiece and the optical path length difference indicating the thickness of the workpiece obtained by the control means constituting the height position measuring apparatus shown in FIG. Illustration. FIG. 2 is a perspective view of an optical device wafer as a workpiece to be processed by the laser processing machine shown in FIG. Explanatory drawing which shows one Embodiment of the laser processing process which forms a deteriorated layer in the optical device wafer shown in FIG. 6 with the laser processing machine shown in FIG. The block block diagram which shows other embodiment of the laser beam machine comprised according to this invention. The block block diagram which shows other embodiment of the laser beam machine comprised according to this invention. Explanatory drawing which shows the relationship with the coordinate position in the state with which the optical device wafer shown in FIG. 6 was hold | maintained in the predetermined position of the chuck table of the laser beam machine shown in FIG. Explanatory drawing of the height position detection process implemented by the measuring device of the workpiece hold | maintained at the chuck table with which the laser beam machine shown in FIG. 9 was equipped. FIG. 10 is an explanatory diagram of a processing step for forming a deteriorated layer on the optical device wafer shown in FIG. 7 by the laser processing machine shown in FIG. 9.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Preferred embodiments of a workpiece measuring apparatus and a laser beam machine held on a chuck table configured according to the invention will be described in detail below with reference to the accompanying drawings.

  FIG. 1 is a perspective view of a laser beam machine equipped with a measuring device for measuring the position of a workpiece held on a chuck table configured according to the present invention. A laser beam machine 1 shown in FIG. 1 includes a stationary base 2 and a chuck table mechanism 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. 3, a laser beam irradiation unit support mechanism 4 disposed on the stationary base 2 so as to be movable in an indexing feed direction (Y axis direction) indicated by an arrow Y orthogonal to the X axis direction, and the laser beam irradiation unit support mechanism 4 And a laser beam irradiation unit 5 arranged to be movable in the condensing point position adjustment direction (Z-axis direction) indicated by an arrow Z.

  The chuck table mechanism 3 includes a pair of guide rails 31 and 31 disposed in parallel along the X-axis direction on the stationary base 2, and is arranged on the guide rails 31 and 31 so as to be movable in the X-axis direction. A first sliding block 32 provided, a second sliding block 33 movably disposed on the first sliding block 32 in the Y-axis direction, and a cylindrical member on the second sliding block 33 And a chuck table 36 as a workpiece holding means. The chuck table 36 includes a suction chuck 361 formed of a porous material, and holds, for example, a circular semiconductor wafer as a workpiece on a holding surface which is the upper surface of the suction chuck 361 by suction means (not shown). It is supposed to be. 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 that supports a workpiece such as a semiconductor wafer via a protective tape.

  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 the lower surface thereof, and is parallel to the upper surface along the X-axis direction. A pair of formed guide rails 322 and 322 are provided. The first sliding block 32 configured in this manner moves in the X-axis direction along the pair of guide rails 31, 31 when the guided grooves 321, 321 are fitted into the pair of guide rails 31, 31. Configured to be possible. The chuck table mechanism 3 in the illustrated embodiment includes a processing feed means 37 for moving the first slide block 32 along the pair of guide rails 31, 31 in the X-axis direction. 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, the first slide block 32 is moved in the X-axis direction along the guide rails 31 and 31 by driving the male screw rod 371 forward and backward by the pulse motor 372.

  The laser beam machine 1 in the illustrated embodiment includes a machining feed amount detection means 374 for detecting the machining 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. When the pulse motor 372 is used as the drive source for 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 Y-axis direction. The chuck table mechanism 3 in the illustrated embodiment has a first index 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 Y-axis direction. A 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, 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 Y-axis direction.

  The laser beam machine 1 in the illustrated embodiment includes index feed amount detection means 384 for detecting the index machining 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. When the pulse motor 382 is used as the drive source of the first indexing and feeding means 38, the drive table 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 382. The index feed amount 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. It is possible to detect the index feed amount of the chuck table 36 by counting.

  The laser beam irradiation unit support mechanism 4 includes a pair of guide rails 41 and 41 disposed in parallel along the Y-axis direction on the stationary base 2 and a direction indicated by an arrow Y on the guide rails 41 and 41. A movable support base 42 is provided so as to be movable. 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 Z-axis direction 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 and 41 in the Y-axis direction. 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 reversely by the pulse motor 432, the movable support base 42 is moved along the guide rails 41, 41 in the Y-axis direction.

  The laser beam irradiation unit 5 in the illustrated embodiment includes a unit holder 51 and a cylindrical unit housing 52 attached to the unit holder 51, and the unit holder 51 is a mounting portion for the movable support base 42. A pair of guide rails 423 and 423 are disposed on the 422 so as to be movable. The unit housing 52 attached to the unit holder 51 is provided with laser beam irradiation means 6 shown in FIG. The laser beam irradiating means 6 includes a pulse laser beam oscillating means 61, a direction changing mirror 62 for changing the direction of the pulse laser beam oscillated from the pulse laser beam oscillating means 61 downward in FIG. 2, and a direction changing by the direction changing mirror 62. A condenser 63 is provided for condensing the pulsed laser beam and irradiating the workpiece W held on the holding surface of the chuck table 36. The pulse laser beam oscillating means 61 includes a pulse laser beam oscillator 611 composed of a YAG laser oscillator or a YVO4 laser oscillator, and a repetition frequency setting means 612 attached thereto, and oscillates a pulse laser beam having a wavelength of 1064 nm, for example. The condenser 63 includes an objective lens 631 that condenses the pulse laser beam oscillated from the pulse laser beam oscillation means 61, and a lens case 632 that accommodates the objective lens 631, and the lens case 632 is a voice coil motor. The first condensing point position adjusting means 64 composed of a linear motor or the like can be moved in the up-down direction in FIG. It has become. The first condensing point position adjusting unit 64 is controlled by a control unit described later.

  Referring back to FIG. 1, the laser processing machine 1 in the illustrated embodiment is configured so that the unit holder 51 is moved along the arrow Z along a pair of guide rails 423 and 423 provided on the mounting portion 422 of the movable support base 42. The second condensing point position adjusting means 53 for moving in the condensing point position adjusting direction (Z-axis direction) shown in FIG. 1, that is, the direction perpendicular to the holding surface of the chuck table 36 is provided. The second condensing point position adjusting means 53 is driven by a male screw rod (not shown) disposed between a pair of guide rails 423 and 423, a pulse motor 532 for rotating the male screw rod, and the like. The laser beam irradiation unit 5 is moved along the guide rails 423 and 423 in the Z-axis direction by driving a male screw rod (not shown) forward and backward by a pulse motor 532. In the illustrated embodiment, the laser beam irradiation unit 5 is moved upward by driving the pulse motor 532 forward, and the laser beam irradiation unit 5 is moved downward by driving the pulse motor 532 in reverse. Yes.

  An imaging means 65 is disposed at the front end of the unit housing 52 constituting the laser beam irradiation unit 5. The imaging unit 65 includes an infrared illumination unit that irradiates a workpiece with infrared rays, an optical system that captures infrared rays emitted by the infrared illumination unit, in addition to a normal imaging device (CCD) that captures visible light. An image sensor (infrared CCD) that outputs an electrical signal corresponding to the infrared rays captured by the optical system is used, and the captured image signal is sent to a control means to be described later.

Returning to FIG. 1 and continuing the description, the laser beam machine 1 in the illustrated embodiment includes a height position measuring device 7 for detecting the position of the workpiece held on the chuck table. The height position measuring device 7 will be described with reference to FIG.
The height position measuring device 7 shown in FIG. 2 emits light having a predetermined wavelength region and guides the light from the light source 71 to the first path 7a including the optical fiber 70 and the first light source 71. An optical branching unit 72 that guides the reflected light that travels backward through the path 7a to the second path 7b, and a detection light irradiation unit that irradiates the workpiece W held on the chuck table 36 with the light guided to the first path 7a. 73. As the light emitting source 71, for example, an LED, an SLD, an LD, a halogen power source, an ASE power source, or a supercontinuum power source that emits light having a wavelength of 820 to 870 nm can be used.

  The detection light irradiating means 73 includes a first collimation lens 731 that forms light guided to the first path 7a into parallel light, and the light formed by the first collimation lens 731 into parallel light as a chuck table. An objective lens 732 that leads to the workpiece W held by 36, and a transparent body that is disposed between the first collimation lens 731 and the objective lens 732 and has a refractive index larger than air and substantially extends the optical path length. And a cylindrical reference optical path length setting member 733. The cylindrical reference optical path length setting member 733 is formed in a cylindrical shape from synthetic quartz glass, and is provided with a light passage hole 733a through which light passes. A light incident portion 733b of the light passage hole 733a is opened on the first collimation lens 731 side of the cylindrical reference optical path length setting member 733, and an annular light receiving surface 733c is formed on an end surface surrounding the light incident portion 733b. Is provided. In addition, a light exit portion 733d of a light passage hole 733a is opened on the objective lens 732 side of the cylindrical reference optical path length setting member 733, and a reflection mirror 733e is formed in an annular surface on an end surface surrounding the light exit portion 733d. ing. The reflection mirror 733e is formed, for example, by vapor-depositing silver on an annular end surface surrounding the light output portion 733d of the cylindrical reference optical path length setting member 733. Since the cylindrical reference optical path length setting member 733 configured in this manner is formed of synthetic quartz glass having a refractive index of 1.45 in the illustrated embodiment, the light received by the annular light receiving surface 733c is formed. The reference optical path length to the reflection mirror 733e is 1.45 times the optical path length from the light incident portion 733b to the light exit portion 733d of the light passage hole 733a.

  A second collimation lens 74, a diffraction grating 75, and a line image sensor 76 are disposed in the second path 7b. The second collimation lens 74 is reflected by the reflection mirror 733e of the cylindrical reference optical path length setting member 733, and reverses the cylindrical reference optical path length setting member 733, the first collimation lens 731 and the first path 7a. The reflected light guided from the light branching means 72 to the second path 2b and the workpiece W held by the chuck table 36 are reflected by the objective lens 732 and the light passage hole 733a of the cylindrical reference optical path length setting member 733. And the first collimation lens 731 and the first path 7a are reversed, and the reflected light guided from the light branching means 72 to the second path 2b is formed into parallel light. The diffraction grating 75 diffracts the interference of both reflected lights formed into parallel light by the second collimation lens 74 and sends a diffraction signal corresponding to each wavelength to the line image sensor 76. The line image sensor 76 detects the light intensity at each wavelength of the reflected light diffracted by the diffraction grating 75 and sends a detection signal to the control means 80.

  The control means 80 obtains a spectral interference waveform from the detection signal from the line image sensor 76, executes a waveform analysis based on the spectral interference waveform and a theoretical waveform function, and forms an annular shape of the cylindrical reference optical path length setting member 733. The reference optical path length of the light received by the light receiving surface 733c to the reflection mirror 733e and the optical path length from the light incident portion 733b of the cylindrical reference optical path length setting member 733 to the workpiece W held on the chuck table 36 An optical path length difference is obtained, and a distance from the surface of the chuck table 36 to the upper surface of the workpiece W held on the chuck table 36 is obtained based on the optical path length difference. That is, the control unit 80 obtains a spectral interference waveform as shown in FIG. 3 based on the detection signal from the line image sensor 76. In FIG. 3, the horizontal axis indicates the wavelength of the reflected light, and the vertical axis indicates the light intensity.

Hereinafter, an example of waveform analysis performed by the control unit 80 based on the spectral interference waveform and a theoretical waveform function will be described.
When the length from the annular light receiving surface 733c of the cylindrical reference optical path length setting member 733 to the reflection mirror 733e is (L), 1.45L multiplied by the refractive index (1.45 in the illustrated embodiment) is obtained. This optical path length becomes the reference optical path length (L1), and the optical path length from the light incident portion 733b of the cylindrical reference optical path length setting member 733 to the workpiece W held on the chuck table 36 is (L2). And the difference between the reference optical path length (L1) and the optical path length (L2) is the optical path length difference (d = L1-L2). In the illustrated embodiment, it is assumed that the optical path length difference (d = L1−L2) is set to 500 μm, for example.

  Next, the control means 80 performs waveform analysis based on the spectral interference waveform and the theoretical waveform function. This waveform analysis can be executed based on, for example, Fourier transformation theory or wavelet transformation theory. In the embodiment described below, examples using the Fourier transformation formulas shown in the following formulas 1, 2, and 3 are used. explain.

In the above formula, λ is a wavelength, d is the optical path length difference (L1−L2), and W (λi) is a window function.
The above Equation 1 shows that the wave period is closest (highly correlated) in comparison between the theoretical waveform of cos and the spectral interference waveform (I (λ _n )), that is, the spectral interference waveform and the theoretical waveform function. An optical path length difference (d) having a high correlation coefficient is obtained. Further, the above formula 2 is obtained by comparing the theoretical waveform of sin and the spectral interference waveform (I (λ _n )) with the closest wave period (high correlation)), that is, the spectral interference waveform and the theoretical waveform. An optical path length difference (d) having a high correlation coefficient with the function is obtained. Then, the above Equation 3 obtains the average value of the result of Equation 1 and the result of Equation 2.

  The control means 80 obtains the optical path length difference (d) having a high signal intensity as shown in FIG. 4 by executing the calculation based on the above-described Equations 1, 2, and 3. In FIG. 4, the horizontal axis indicates the optical path length difference (d), and the vertical axis indicates the signal intensity. 4A shows the case where the optical path length difference (d) is 630 μm. In this case, the distance from the surface of the chuck table 36 to the surface (upper surface) of the workpiece W is 130 μm in the illustrated embodiment. . FIG. 4B shows a case where the optical path length difference (d) is 580 μm. In this case, the distance from the surface of the chuck table 36 to the surface (upper surface) of the workpiece W is 80 μm in the illustrated embodiment. . As described above, the distance from the surface of the chuck table 36 to the upper surface of the workpiece W is determined by performing waveform analysis based on the spectral interference waveform and the theoretical waveform function to obtain the optical path length difference (d). Can be sought. The control unit 80 displays the analysis result shown in FIG.

In the above-described embodiment, the case where the workpiece W does not transmit light in the wavelength region as in the case of a silicon wafer has been described. Next, the workpiece W is formed of a material that transmits light, such as sapphire or glass. The case where this is done will be described.
In the case of the workpiece W through which light is transmitted, the light irradiated to the workpiece W is reflected by the reflected light reflected by the surface (upper surface) of the workpiece W and by the rear surface (lower surface) of the workpiece W. Reflected light is generated, and both the reflected light travels backward through the objective lens 732, the light passage hole 733a of the cylindrical reference optical path length setting member 733, the first collimation lens 731 and the first path 7a, and the first light. It is led from the branching means 72 to the second path 2b. On the other hand, as described above, the reflected light reflected by the reflecting mirror 733e of the cylindrical reference optical path length setting member 733 also travels backward through the cylindrical reference optical path length setting member 733, the first collimation lens 731 and the first path 7a. Then, the light is guided from the first light branching means 72 to the second path 2b. Each reflected light guided to the second path 6 b in this way is formed into parallel light by the second collimation lens 74, further diffracted by the diffraction grating 75, and guided to the line image sensor 76. The line image sensor 76 detects the light intensity at each wavelength of the reflected light diffracted by the diffraction grating 75 and sends a detection signal to the control means 80. As described above, based on the spectral interference waveform and the theoretical waveform function of the reflected light reflected by the reflection mirror 733e of the front surface (upper surface) and the back surface (lower surface) of the workpiece W and the cylindrical reference optical path length setting member 733. When the waveform analysis described above is executed, three optical path length differences (d) with high signal intensity are obtained as shown in FIG. In FIG. 5, the horizontal axis represents the optical path length difference (d), and the vertical axis represents the signal intensity. In the example shown in FIG. 5, the signal intensity is high at the position where the optical path length difference (d) is 620 μm, the optical path length difference (d) is 500 μm, and the optical path length difference (d) is 120 μm. The signal intensity (A) at the position where the optical path length difference (d) is 620 μm represents the surface (upper surface) of the workpiece W. In this case, the distance from the surface of the chuck table 36 to the surface (upper surface) of the workpiece W is In the illustrated embodiment, it is 120 μm. Further, the signal intensity (B) at the position where the optical path length difference (d) is 500 μm represents the back surface (lower surface) of the workpiece W, and in this case, from the surface of the chuck table 36 to the back surface (lower surface) of the workpiece W. The distance is zero (0) in the illustrated embodiment. On the other hand, the signal intensity (C) at the position where the optical path length difference (d) is 120 μm represents the thickness of the workpiece W, and it is directly required that the thickness of the workpiece W is 120 μm. The control means 80 displays the analysis result shown in FIG.

The laser beam machine 1 in the illustrated embodiment is configured as described above, and the operation thereof will be described below.
FIG. 6 is a perspective view of an optical device wafer 10 as a workpiece to be laser processed. An optical device wafer 10 shown in FIG. 6 is made of a sapphire wafer having a thickness of, for example, 100 μm, and includes a plurality of streets 101 in which optical device layers made of a gallium nitride compound semiconductor are stacked on the surface 10a and formed in a lattice shape. An optical device 102 such as a light emitting diode or a laser diode is formed in a plurality of partitioned areas.

  An embodiment of laser processing that uses the laser processing machine 1 described above to irradiate a laser beam along the street 101 of the optical device wafer 10 and form a deteriorated layer along the street 101 inside the optical device wafer 10 will be described. . When the altered layer is formed inside the optical device wafer 10, if the thickness of the optical device wafer 10 varies, the altered layer is uniformly formed at a predetermined depth due to the refractive index as described above. Can not do it. Therefore, when laser processing is performed, a laser beam is irradiated while measuring the upper surface position of the optical device wafer 10 held on the holding surface of the chuck table 36 by the height position measuring device 7 described above.

  In order to irradiate the laser beam while measuring the upper surface position of the optical device wafer 10 held on the holding surface of the chuck table 36 by the height position measuring device 7, first, the chuck table 36 of the laser processing machine shown in FIG. The optical device wafer 10 is placed on the holding surface with the back surface 10b of the optical device wafer 10 up, and the optical device wafer 10 is sucked and held on the holding surface of the chuck table 36. When the optical device wafer 10 is sucked and held on the chuck table 36 in this way, the processing feed means 37 is operated to position the chuck table 36 directly below the imaging means 65.

  When the chuck table 36 is positioned immediately below the image pickup means 65, the image pickup means 65 and the control means 90 execute an alignment operation for detecting a processing region to be laser processed of the optical device wafer 10. That is, the image pickup means 65 and the control means 80 are patterns for aligning a street 101 formed in a predetermined direction of the optical device wafer 10 and a condenser 63 that irradiates a laser beam along the street 101. Image processing such as matching is executed, and alignment of detection positions is performed. Similarly, the alignment of the detection position is performed on the street 101 formed in the direction orthogonal to the predetermined direction formed in the optical device wafer 10. At this time, the surface 10a on which the street 101 of the optical device wafer 10 is formed is positioned on the lower side, but the sapphire wafer forming the optical device wafer 10 is a transparent body, so Can be imaged.

  As described above, when the street 101 formed on the optical device wafer 10 held on the holding surface of the chuck table 36 is detected and the alignment of the laser beam irradiation position is performed, the processing feeding means 37 and the first feeding device 37 are arranged. As shown in FIG. 7A, the index feed means 38 is operated to move the chuck table 36 to the laser beam irradiation area where the condenser 63 of the laser beam irradiation means 6 is located, and to one end of the predetermined street 101 (FIG. 7). (The left end in (a)) is positioned directly below the detection light irradiation means 73 constituting the height position measuring device 7. Next, the height position measuring device 7 is activated and the machining feed means 37 is activated to move the chuck table 36 at a predetermined machining feed speed in the machining feed direction indicated by the arrow X1 in FIG. By operating the height position measuring device 7 in this manner, the height position along the predetermined street 101 on the upper surface (back surface) of the optical device wafer 10 is measured as described above. Then, the control unit 80 determines the height position of the upper surface (back surface) corresponding to the movement position of the optical device wafer 10 based on the detection signal from the processing feed amount detection unit 374 and the measurement signal from the height position measurement device 7. As described above, the height position of the upper surface (back surface) corresponding to the moving position of the optical device wafer 10 is stored in the built-in memory.

  Next, the control means 80 obtains the movement distance of the chuck table 36 in the direction indicated by X1 based on the detection signal sent from the machining feed amount detection means 374. When the moving distance reaches the center-to-center distance S between the detection light irradiating means 73 and the condenser 63 as shown in FIG. 7 (b), the control means 80 ends one end of a predetermined street 101 of the optical device wafer 10. It is determined that (the left end in FIG. 7B) has reached directly below the condenser 63, the laser beam application means 6 is activated, and a pulsed laser beam is emitted from the collector 63. At this time, the control means 80 applies the pulse laser beam emitted from the condenser 63 based on the height position of the upper surface (back surface) of one end (the left end in FIG. 7B) of the street 101 stored in the memory. The first condensing point position adjusting means 64 is controlled so that the condensing point P is located at a depth position of a predetermined distance (for example, 50 μm) from the height position of the upper surface (back surface) of the street 101. Thereafter, the control means 80 delays the distance S between the detection light irradiation means 73 and the condenser 63 by the center S based on the detection signal sent from the machining feed amount detection means 374 and the measurement signal from the detection light irradiation means 73. The first condensing is performed such that the condensing point P of the pulse laser beam emitted from the concentrator 63 is positioned at a predetermined distance (for example, 50 μm) from the height position of the upper surface (back surface) of the street 101. The point position adjusting means 64 is controlled. Then, as shown in FIG. 7C, when the other end of the street 101 (the right end in FIG. 7B) reaches the irradiation position of the condenser 63, the control means 80 stops the irradiation of the pulse laser beam. At the same time, the movement of the chuck table 36 is stopped (laser processing step). As a result, an altered layer 110 is formed in the optical device wafer 10 in parallel with the back surface 10b (upper surface) at a predetermined depth from the back surface 10b (upper surface) as shown in FIG.

In addition, the processing conditions in the said laser processing process are set as follows, for example.
Laser beam: LD excitation Q switch Nd: YVO4 laser Wavelength: 1064 nm pulse laser Repetition frequency: 80 kHz
Pulse width: 120 ns
Average output: 1.2W
Condensing spot diameter: φ2μm
Processing feed rate: 100 mm / sec

  As described above, when the laser processing step is executed along all the streets 101 extending in the predetermined direction of the optical device wafer 10, the chuck table 36 is rotated 90 degrees to Then, the laser processing step is executed along each street 101 extending in a direction orthogonal to each other. In this way, if the laser processing step is performed along all the streets 101 formed on the optical device wafer 10, the chuck table 36 holding the optical device wafer 10 is the first to hold the optical device wafer 10. Is returned to the position where the suction is held, and the suction holding of the optical device wafer 10 is released here. Then, the optical device wafer 10 is transported to the dividing step by a transport means (not shown).

Next, another embodiment of a laser beam machine configured according to the present invention will be described with reference to FIG. In the embodiment shown in FIG. 8, the same members as those of the laser beam machine shown in FIG.
The laser processing machine shown in FIG. 8 includes two detection light irradiating means 73a and 73b, which are disposed close to the condenser 63 of the laser beam irradiating means 6 and on both sides in the processing feed direction (X-axis direction). . The optical switch 9 is arranged between the optical branching unit 72 and the optical fibers 70a, 70b constituting the first path 7a formed between the optical branching unit 72 and the two detection light irradiating units 73a, 73b. It is installed. The optical switch 9 switches between the reflected light guided from the one detection light irradiation means 73a to the optical fiber 70a and the reflected light guided from the other detection light irradiation means 73b to the optical fiber 70b, and optically branches one of them. It has a function of leading to the means 72 and is controlled by the control means 80. The other constituent members in the laser beam machine shown in FIG. 8 are substantially the same as those in the laser beam machine shown in FIG. Thus, the chuck table 36 is processed by disposing the two detection light irradiation means 73a and 73b close to the condenser 63 of the laser beam irradiation means 6 and on both sides in the processing feed direction (X-axis direction). When reciprocating in the feed direction (X-axis direction), laser processing can be performed while measuring the height position of the upper surface of the workpiece held on the chuck table 36.

Next, still another embodiment of the laser beam machine configured according to the present invention will be described with reference to FIG. In the embodiment shown in FIG. 9, the same members as those of the laser beam machine shown in FIG.
The laser beam machine shown in FIG. 9 condenses the light that has passed through the light passage hole 733 a of the cylindrical reference optical path length setting member 733 constituting the detection light irradiation means 73 of the height position measuring device 7. The workpiece held on the chuck table 36 is irradiated through the objective lens 631 constituting the vessel 63. The laser beam irradiation means is disposed between the cylindrical reference optical path length setting member 733 constituting the detection light irradiation means 73 of the height position measuring device 7 and the objective lens 631 constituting the condenser 63 of the laser beam irradiation means 6. A dichroic mirror 65 for changing the direction of the pulse laser beam oscillated from the six pulse laser beam oscillation means 61 toward the objective lens 631 constituting the condenser 63 is provided. The dichroic mirror 65 allows light from the light passage hole 733 a of the cylindrical reference optical path length setting member 733 to pass, but changes the direction of the pulse laser beam oscillated from the pulse laser beam oscillation means 61 toward the objective lens 631. Further, between the cylindrical reference optical path length setting member 733 and the dichroic mirror 65, the parallel light formed by the first collimation lens 731 is condensed, and the focal point is positioned on the objective lens 631. The condensing lens 66 which produces | generates the light from quasi-parallel light is arrange | positioned. As described above, the condenser lens 66 is disposed between the cylindrical reference optical path length setting member 733 and the dichroic mirror 65, and the light from the objective lens 631 is generated in the quasi-parallel light, thereby being held on the chuck table 36. When the reflected light reflected by the processed workpiece W goes back through the objective lens 631, the condenser lens 66, the light passage hole 733 a of the cylindrical reference optical path length setting member 733 and the first collimation lens 731, It is possible to converge on the optical fiber 70 constituting the one path 7a. In the laser processing machine configured as described above, the objective lens 631 constituting the condenser 63 of the laser beam irradiation means 6 functions as an objective lens constituting the detection light irradiation means 73 of the height position measuring device 7. It is configured.

The laser beam machine in the embodiment shown in FIG. 9 is configured as described above, and the operation thereof will be described below.
An embodiment of laser processing using the laser processing machine shown in FIG. 9 to irradiate a laser beam along the street 101 of the optical device wafer 10 and form a deteriorated layer along the street 101 inside the optical device wafer 10. explain. Specifically, the optical device wafer 10 is first placed on the chuck table 36 with the back surface 10b of the optical device wafer 10 facing up, and the optical device wafer 10 is sucked and held on the chuck table 36. And the alignment operation | work which detects the process area | region which should carry out the laser processing of the optical device wafer 10 as mentioned above is performed.

  When alignment is performed as described above, the optical device wafer 10 on the chuck table 36 is positioned at the coordinate position shown in FIG. FIG. 10B shows a state where the chuck table 36, that is, the optical device wafer 10, is rotated by 90 degrees from the state shown in FIG.

  It should be noted that the feed start position coordinate values (A1, A2, A3,...) Of each street 101 formed on the optical device wafer 10 in the state positioned at the coordinate positions shown in FIGS.・ An) and feed end position coordinate values (B1, B2, B3 ... Bn), feed start position coordinate values (C1, C2, C3 ... Cn) and feed end position coordinate values (D1, D2, D3 ... Dn), the design value data is stored in the memory of the control means 80.

  As described above, when the street 101 formed on the optical device wafer 10 held on the chuck table 36 is detected and the detection position is aligned, the chuck table 36 is moved to move to (a) of FIG. ), The uppermost street 101 is positioned immediately below the condenser 63 of the laser beam irradiation means 6. Further, as shown in FIG. 11, the feed start position coordinate value (A1) (see FIG. 10A), which is one end (the left end in FIG. 8) of the street 101, is obtained from the objective lens 631 constituting the condenser 63. Position directly below. Then, the position measuring device 7 is operated, and the chuck table 36 is moved in the direction indicated by the arrow X1 in FIG. 11 to move to the feed end position coordinate value (B1) (height position detecting step). As a result, the height position of the upper surface is measured by the height position measuring device 7 along the uppermost street 101 in FIG. 10A of the optical device wafer 10 as described above. The measured optical path length difference (d) and height position are stored in the memory of the control means 80. In this way, the height position detection step is performed along all the streets 101 formed on the optical device wafer 10, and the height position of the upper surface of each street 101 is stored in the memory of the control means 80.

When the height position detecting step is performed along all the streets 101 formed on the optical device wafer 10 as described above, laser processing for forming a deteriorated layer along the street 101 inside the optical device wafer 10. To implement.
In order to carry out this laser processing, first, the chuck table 36 is moved, and the uppermost street 101 in FIG. 10A is directly below the condenser lens 631 constituting the condenser 63 of the laser beam irradiation means 6. Position. Further, as shown in FIG. 12A, the feed start position coordinate value (A1) (see FIG. 9A) which is one end of the street 101 (the left end in FIG. 12A) is used as the objective lens 631. Position directly below. Then, the condensing point P of the pulse laser beam irradiated from the objective lens 631 constituting the condenser 63 of the laser beam irradiation means 6 is set to a predetermined depth position from the back surface 10b (upper surface) of the optical device wafer 10. Next, the laser beam irradiation means 6 is operated to move the chuck table 36 in the direction indicated by the arrow X1 at a predetermined processing feed speed while irradiating the objective lens 631 with a pulse laser beam (laser processing step). Then, as shown in FIG. 12B, when the irradiation position of the objective lens 631 reaches the other end of the street 101 (the right end in FIG. 12B), the irradiation of the pulse laser beam is stopped and the chuck table 36 is stopped. Stop moving. In this laser processing step, the control means 80 controls the first focusing point position adjusting means 64 based on the height position of the back surface 10b (upper surface) of the street 101 of the optical device wafer 10 stored in the memory. Then, the condenser 63 is moved in the Z-axis direction (condensing point position adjusting direction), and the objective lens 631 constituting the condenser 63 of the laser beam irradiation means 6 is changed to an optical device as shown in FIG. The wafer 10 is moved in the vertical direction corresponding to the height position of the back surface 10b (upper surface) of the street 101. In the control of the first condensing point position adjusting unit 64, the control unit 80 controls the optical path length difference (d) to be a predetermined value. As a result, an altered layer 110 is formed in the optical device wafer 10 in parallel with the back surface 10b (upper surface) at a predetermined depth from the back surface 10b (upper surface) as shown in FIG.

The processing conditions in the laser processing step may be the same as the processing conditions in the laser processing step shown in FIG.
As described above, when the laser processing step is executed along all the streets 101 extending in the predetermined direction of the optical device wafer 10, the chuck table 36 is rotated 90 degrees to Then, the laser processing step is executed along each street 101 extending in a direction orthogonal to each other. In this way, if the laser processing step is performed along all the streets 101 formed on the optical device wafer 10, the chuck table 36 holding the optical device wafer 10 is the first to hold the optical device wafer 10. Is returned to the position where the suction is held, and the suction holding of the optical device wafer 10 is released here. Then, the optical device wafer 10 is transported to the dividing step by a transport means (not shown).

  As mentioned above, although the example which applied the measuring device of the workpiece hold | maintained at the chuck table by this invention to the laser processing machine was shown, the measuring device by this invention is other processing machines, such as a cutting machine equipped with the cutting blade. You may apply to.

2: Stationary base 3: Chuck table mechanism 36: Chuck table 37: Processing feed means 374: Processing feed amount detection means 38: First index feeding means 4: Laser beam irradiation unit support mechanism 5: Laser beam irradiation unit 53: Second 6: Laser beam irradiation means 61: Pulse laser beam oscillation means 63: Condenser 631: Objective lens 64: First focusing point position adjustment means 65: Imaging means 7: Height position measuring device 71 : Light emission source 72: Light branching means 73: Detection light irradiation means 731: First collimation lens 732: Objective lens 733: Cylindrical reference optical path length setting member 74: Second collimation lens 75: Diffraction grating 76: Line image Sensor 80: Control means 10: Optical device wafer

Claims (7)

In the workpiece height position measuring device for detecting the position of the workpiece held on the holding surface of the chuck table,
A light emitting source that emits light having a predetermined wavelength region;
Light branching means for guiding the light from the light emitting source to the first path and for guiding the reflected light that travels backward through the first path to the second path;
A collimation lens that forms light guided to the first path into parallel light;
An objective lens that guides light formed into parallel light by the collimation lens to a workpiece held by the chuck table;
A light passage hole disposed between the collimation lens and the objective lens for allowing light to pass therethrough has an annular light receiving surface on the end surface on the collimation lens side and an annular reflection mirror on the end surface on the objective lens side A cylindrical reference optical path length setting member made of a transparent body having a refractive index larger than air and substantially extending the optical path length,
Reflected light reflected by the reflecting mirror of the reference optical path length setting member and guided back to the second path from the light branching means by going back the reference optical path length setting member, the collimation lens, and the first path; Reflected by the workpiece held on the chuck table, the objective lens, the light passage hole of the reference optical path length setting member, the collimation lens, and the first path are moved backward from the light branching means to the second light path. A diffraction grating that diffracts interference with reflected light guided along the path of
An image sensor for detecting light intensity in a predetermined wavelength range of reflected light diffracted by the diffraction grating;
A spectral interference waveform is obtained based on a detection signal from the image sensor, a waveform analysis is performed based on the spectral interference waveform and a theoretical waveform function, and an annular reflection from the annular light receiving surface of the reference optical path length setting member. The optical path length difference between the reference optical path length to the mirror and the optical path length from the light incident portion of the light passage hole of the reference optical path length setting member to the workpiece held on the chuck table is obtained. Control means for obtaining a distance from the surface of the chuck table to the upper surface of the workpiece held on the chuck table based on
An apparatus for measuring a workpiece held on a chuck table. A chuck table having a holding surface for holding the workpiece, a laser beam irradiation means for irradiating the workpiece held on the holding surface of the chuck table with a laser beam, and a chucking direction of the chuck table and the laser beam irradiation means. A laser beam oscillator that oscillates a laser beam, and a processing unit that moves relative to the chuck table and a height position measuring device that detects the position of the workpiece held on the holding surface of the chuck table. And a condensing device for condensing the laser beam oscillated from the laser beam oscillator and irradiating the workpiece held on the holding surface of the chuck table,
The height position measuring device includes a light emitting source that emits light having a predetermined wavelength region;
Light branching means for guiding the light from the light emitting source to the first path and for guiding the reflected light that travels backward through the first path to the second path;
A collimation lens that forms light guided to the first path into parallel light;
An objective lens that guides light formed into parallel light by the collimation lens to a workpiece held by the chuck table;
A light passage hole disposed between the collimation lens and the objective lens for allowing light to pass therethrough has an annular light receiving surface on the end surface on the collimation lens side and an annular reflection mirror on the end surface on the objective lens side A cylindrical reference optical path length setting member made of a transparent body having a refractive index larger than air and substantially extending the optical path length,
Reflected light reflected by the reflecting mirror of the reference optical path length setting member and guided back to the second path from the light branching means by going back the reference optical path length setting member, the collimation lens, and the first path; The light beam is reflected by the workpiece held on the chuck table and travels backward through the objective lens, the condenser lens, the light passage hole of the reference optical path length setting member, the collimation lens, and the first path. A diffraction grating for diffracting interference with reflected light guided from the means to the second path;
An image sensor for detecting light intensity in a predetermined wavelength range of reflected light diffracted by the diffraction grating;
A spectral interference waveform is obtained based on a detection signal from the image sensor, a waveform analysis is executed based on the spectral interference waveform and a theoretical waveform function, and an annular reflection mirror is formed from the annular light receiving surface of the reference optical path length setting member The optical path length difference between the reference optical path length up to and the optical path length from the light incident portion of the light passage hole of the reference optical path length setting member to the workpiece held on the chuck table is determined based on the optical path length difference. And a control means for obtaining a distance from the surface of the chuck table to the upper surface of the workpiece held on the chuck table,
The detection light irradiation means is disposed adjacent to the condenser;
Laser processing machine characterized by that. Condensing point position adjusting means for moving the condenser of the laser beam irradiation means in a condensing point position adjusting direction perpendicular to the holding surface of the chuck table,
The control means includes a reference optical path length from the light receiving surface of the reference optical path length setting member to the annular reflecting mirror, and a work piece held on the chuck table from a light incident portion of the light passage hole of the reference optical path length setting member. 3. The laser processing apparatus according to claim 2, wherein the condensing point position adjusting means is controlled based on an optical path length difference from an optical path length to an object.   The laser processing apparatus according to claim 2 or 3, wherein the detection light irradiation means is disposed on both sides of the collector in a processing feed direction. A chuck table having a holding surface for holding a workpiece, laser beam irradiation means for irradiating the workpiece held on the chuck table with a laser beam, and detecting a height position of the workpiece held on the chuck table A laser processing machine comprising:
The measuring device includes a light emitting source that emits light having a predetermined wavelength region;
Light branching means for guiding the light from the light emitting source to the first path and for guiding the reflected light that travels backward through the first path to the second path;
A collimation lens that forms light guided to the first path into parallel light;
An objective lens that guides light formed into parallel light by the collimation lens to a workpiece held by the chuck table;
A light passage hole disposed between the collimation lens and the objective lens for allowing light to pass therethrough has an annular light receiving surface on the end surface on the collimation lens side and an annular reflection mirror on the end surface on the objective lens side A cylindrical reference optical path length setting member made of a transparent body having a refractive index larger than air and substantially extending the optical path length,
Reflected light reflected by the reflecting mirror of the reference optical path length setting member and guided back to the second path from the light branching means by going back the reference optical path length setting member, the collimation lens, and the first path; Reflected by the workpiece held on the chuck table, the objective lens, the light passage hole of the reference optical path length setting member, the collimation lens, and the first path are moved backward from the light branching means to the second light path. A diffraction grating that diffracts interference with reflected light guided along the path of
An image sensor for detecting light intensity in a predetermined wavelength range of reflected light diffracted by the diffraction grating;
A spectral interference waveform is obtained based on a detection signal from the image sensor, a waveform analysis is performed based on the spectral interference waveform and a theoretical waveform function, and from the light receiving surface of the reference optical path length setting member to the annular reflection mirror The optical path length difference between the reference optical path length of the optical path length and the optical path length from the light incident portion of the light passage hole of the reference optical path length setting member to the workpiece held on the chuck table is determined based on the optical path length difference. Control means for obtaining a distance from the surface of the chuck table to the upper surface of the workpiece held on the chuck table,
The laser beam irradiation unit includes a laser beam oscillation unit that oscillates a laser beam, a laser beam oscillated from the laser beam oscillation unit that is disposed between the reference optical path length setting member and the objective lens, and changes the direction of the laser beam toward the objective lens. A dichroic mirror
Laser processing machine characterized by that.   The parallel light formed by the collimation lens disposed between the reference optical path length setting member and the dichroic mirror is condensed, the focal point is positioned on the objective lens, and the light from the objective lens is quasi-parallel light The workpiece measuring apparatus according to claim 5, further comprising a condensing lens to be generated. Condensing point position adjusting means for moving the objective lens of the laser beam irradiation means in a condensing point position adjusting direction perpendicular to the holding surface of the chuck table,
The control means includes a reference optical path length from the light receiving surface of the reference optical path length setting member to the annular reflecting mirror, and a work piece held on the chuck table from a light incident portion of the light passage hole of the reference optical path length setting member. The laser processing apparatus according to claim 5 or 6, wherein the condensing point position adjusting means is controlled based on an optical path length difference from an optical path length to an object.

Images