JP5420890B2 - Device for measuring the height position of the workpiece held on the chuck table - Google Patents

Description

  The present invention relates to a height position measuring device for detecting the upper surface height position of a workpiece such as a semiconductor wafer held on a chuck table provided in 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 devices. In addition, optical device wafers with gallium nitride compound semiconductors laminated on the surface of sapphire substrates are also divided into individual optical devices such as light-emitting diodes and laser diodes by cutting along the planned division lines, and are widely used in electrical equipment. It's being used.

As a method of dividing along the streets of the semiconductor wafer and the optical device wafer described above, a pulsed laser beam having transparency to the wafer is used, and the focused laser beam is irradiated with the focused laser beam within the region to be divided. Laser processing methods have also been attempted. The dividing method using this laser processing method is to irradiate a pulse laser beam having a wavelength of 1064 nm, for example, having a light converging point from one surface side of the wafer and having the light converging point inside, so that a street is formed inside the wafer. The deteriorated layer is continuously formed along the cut line, and the workpiece is divided by applying an external force along the planned dividing line whose strength is reduced by the formation of the deteriorated layer. (For example, refer to Patent Document 1.)
Japanese Patent No. 3408805

  However, a plate-like workpiece such as a semiconductor wafer has undulation, and if the thickness varies, a uniform alteration layer is formed at a predetermined depth due to the refractive index when irradiating a laser beam. I can't. Therefore, in order to uniformly form a deteriorated layer at a predetermined depth inside a semiconductor wafer or the like, it is necessary to detect irregularities in a region irradiated with a laser beam in advance and to process the irregularities by following the laser beam irradiation means. .

In order to solve the above-described problem, a laser beam irradiation means including a collector for irradiating a workpiece held on a chuck table with a laser beam to generate a focusing point, and a focusing point generated by the collector A focusing point position adjusting means for moving the workpiece in a direction perpendicular to the workpiece holding surface, and a height position detecting means for detecting a height position of the workpiece held on the chuck table immediately before the laser beam is irradiated. There has been proposed a laser processing apparatus including a control means for controlling the focusing point position adjusting means based on the height position signal detected by the height position detecting means. (For example, see Patent Document 2.)
Japanese Patent Laid-Open No. 2008-12566

  However, in the laser processing apparatus disclosed in Patent Document 2, even if the height position immediately before the laser beam is irradiated is detected by the height position detecting means, a slight time shift occurs, so the height is detected. It is difficult to accurately adjust the position of the condensing point of the laser beam irradiated from the laser beam irradiation unit accurately following the height position detected by the position detection unit.

On the other hand, as a technique for solving the above-described problems, a height position detecting means for detecting the height position of the work placed on the chuck table is provided, and the height of the workpiece cutting region is provided by the height position detecting means. A dicing apparatus has been proposed in which a height map of a cutting area is created by measuring a position, and a cutting position of a cutting blade is controlled based on the map. (For example, refer to Patent Document 3.)
Japanese Patent Laid-Open No. 2003-168655

  Thus, by applying the technique disclosed in Patent Document 3 above, to measure the height positions of a plurality of streets formed on the wafer placed on the chuck table, to create a height map, Since the height position is detected for each street, it takes a detection time in proportion to the number of streets, so there is a problem that productivity is poor.

  The present invention has been made in view of the above-mentioned facts, and its main technical problem is that the work piece held on the chuck table is held on the chuck table capable of simultaneously measuring the upper surface height position over a wide range. Another object of the present invention is to provide a height position measuring device for a workpiece.

In order to solve the main technical problem, according to the present invention, a chuck table for holding a workpiece, and a height position detecting means for detecting an upper surface height position of the workpiece held on the chuck table, X-axis direction moving means for relatively moving the chuck table and the height position detecting means in the X-axis direction, and X-axis direction position detecting means for detecting the X-axis direction position of the chuck table. In the workpiece height position measuring device held by the chuck table,
The high position detection means includes a multi-wavelength light source, and gray te Ingumira for splitting the Y-axis direction corresponding to the wavelength of the detection light multi-wavelength light source emits light perpendicular to the X-axis direction, the gray pos- sesses A first chromatic aberration correcting condensing lens that condenses the detection light dispersed by the mirror and irradiates the upper surface of the workpiece held on the chuck table, and irradiates through the first chromatic aberration correcting condensing lens. A second chromatic aberration correcting condensing lens that condenses the detection light reflected by the upper surface of the workpiece held by the chuck table, and the detection light condensed by the second chromatic aberration correcting condensing lens. A light receiving means having a plurality of CCD pixels in a matrix in the Y-axis direction and the Z-axis direction for receiving light, and a height position of the workpiece based on a detection signal from the X-axis direction position detecting means and the light receiving means. A control means to obtain, And Bei,
The detection light that is split in the Y-axis direction by the grating mirror and irradiated through the first chromatic aberration correcting condenser lens is set in a range corresponding to the length of the workpiece in the Y-axis direction,
The light receiving means includes a plurality of pixels arranged in a matrix in the X-axis direction and the Z-axis direction perpendicular to the Y-axis direction corresponding to the wavelength of the detection light dispersed in the Y-axis direction,
The control means obtains the position in the Z-axis direction in the X and Y coordinate values of the workpiece based on the detection signals from the X-axis direction position detection means and the light receiving means.
An apparatus for measuring a height position of a workpiece held on a chuck table.

  The multi-wavelength light source is preferably a white light source.

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, and the light receiving means for receiving the detection light collected by the second chromatic aberration correcting type condensing lens is the Y axis. comprising a plurality of CCD pixels in a matrix in a direction Z-axis direction, the detection light is irradiated through the first chromatic aberration correcting type light-condensing lens is split into a Y-axis direction by the gray Te Ingumira emitted from the multi-wavelength light source, Since it is set in a range corresponding to the length of the workpiece in the Y-axis direction, the height position of the workpiece in the Y-axis direction can be detected simultaneously. Therefore, the position in the Z-axis direction in the X and Y coordinate values of the workpiece can be obtained based on the light receiving signal received by the light receiving means of the height position detecting means while moving the chuck table in the X-axis direction. The height position (Z-axis direction position) of each workpiece in the X and Y coordinates can be obtained by one scan.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a preferred embodiment of a workpiece height position measuring device held on a chuck table configured according to the present invention will be described in more detail with reference to the accompanying drawings.

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

  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 A cover table 35 supported by 34 and a chuck table 36 as a workpiece holding means are provided. The chuck table 36 includes a suction chuck 361 formed of a porous material, and holds, for example, a disk-shaped semiconductor wafer, which is a workpiece, on the suction chuck 361 by suction means (not shown). . The chuck table 36 configured as described above is rotated by a pulse motor (not shown) disposed in the cylindrical member 34. The chuck table 36 is provided with a clamp 362 for fixing an annular frame described later.

  The first sliding block 32 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 way 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 X-axis direction moving means 37 for moving the first sliding block 32 along the pair of guide rails 31, 31 in the X-axis direction. The X-axis direction moving 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. Yes. 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 sliding block 32 is moved along the guide rails 31 and 31 in the X-axis direction by driving the male screw rod 371 forward and backward by the pulse motor 372.

  The laser beam machine in the illustrated embodiment includes X-axis direction position detecting means 374 for detecting the X-axis direction position of the chuck table 36. The X-axis direction position detecting means 374 is a linear scale 374a disposed along the guide rail 31, and a reading that is disposed along the linear scale 374a together with the first sliding block 32 disposed along the first sliding block 32. It consists of a head 374b. In the illustrated embodiment, the read head 374b of the X-axis direction position detecting means 374 sends a pulse signal of one pulse every 1 μm to the control means described later. The control means described later detects the position of the chuck table 36 in the X-axis direction by counting the input pulse signals.

  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 includes a first Y for moving the second sliding block 33 in the Y-axis direction along a pair of guide rails 322 and 322 provided in the first sliding block 32. An axial movement means 38 is provided. The first Y-axis direction moving 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. Is included. 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 in the illustrated embodiment includes Y-axis direction position detecting means 384 for detecting the Y-axis direction position of the second sliding block 33. The Y-axis direction position detecting means 384 is a linear scale 384a disposed along the guide rail 322, and a reading which is disposed along the linear scale 384a together with the second sliding block 33 disposed along the second sliding block 33. And a head 384b. In the illustrated embodiment, the reading head 384b of the Y-axis direction position detecting means 384 sends a pulse signal of one pulse every 1 μm to the control means described later. The control means described later detects the position of the chuck table 36 in the Y-axis direction by counting the input pulse signals.

  The laser beam irradiation unit support mechanism 4 is movable in the Y-axis direction on a pair of guide rails 41, 41 arranged in parallel along the Y-axis direction on the stationary base 2. The movable support base 42 is provided. 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 second Y-axis direction moving means 43 for moving the movable support base 42 in the Y-axis direction along the pair of guide rails 41, 41. Yes. The second Y-axis direction moving 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. Is included. 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 laser beam irradiation means 52 attached to the unit holder 51. The unit holder 51 is provided with a pair of guided grooves 511 and 511 that are slidably fitted to a pair of guide rails 423 and 423 provided in the mounting portion 422. By being fitted to the guide rails 423 and 423, the guide rails 423 and 423 are supported so as to be movable in the Z-axis direction.

  The laser beam irradiation unit 5 in the illustrated embodiment has a condensing point position adjustment for moving the unit holder 51 in a condensing point position adjusting direction (Z-axis direction) indicated by an arrow Z along the pair of guide rails 423 and 423. Means 53 are provided. The condensing point position adjusting means 53 includes a male screw rod (not shown) disposed between the pair of guide rails 423 and 423, and a drive source such as a pulse motor 532 for rotationally driving the male screw rod. The male screw rod (not shown) is driven to rotate forward and reverse by the pulse motor 532, so that the unit holder 51 and the laser beam irradiation means 52 are moved along the guide rails 423 and 423 in the condensing point position adjustment direction indicated by the arrow Z ( Move in the Z-axis direction). In the illustrated embodiment, the laser beam irradiation means 52 is moved upward by driving the pulse motor 532 forward, and the laser beam irradiation means 52 is moved downward by driving the pulse motor 532 in reverse. Yes.

  The laser beam irradiation unit 5 in the illustrated embodiment includes Z-axis direction position detection means 55 for detecting the position of the laser beam irradiation means 52 in the Z-axis direction. The Z-axis direction position detecting means 55 includes a linear scale 551 disposed in parallel with the guide rails 423 and 423, a reading head 552 attached to the unit holder 51 and moving along with the unit holder 51 along the linear scale 551. It is made up of. In the illustrated embodiment, the reading head 552 of the Z-axis direction position detecting means 55 sends a pulse signal of one pulse every 1 μm to the control means described later.

  The illustrated laser beam application means 52 includes a cylindrical casing 521 arranged substantially horizontally. In the casing 521, pulse laser beam oscillation means for oscillating a pulse laser beam having a wavelength (for example, 1064 nm) that is transmissive to a wafer as a workpiece is disposed. A concentrator 6 is provided at the tip of the cylindrical casing 521 for condensing the pulse laser beam oscillated by the pulse laser beam oscillating means and irradiating the workpiece held on the chuck table 36. Yes.

The laser beam machine according to the embodiment includes a height position detection unit 7 that is attached to the tip of the cylindrical casing 521 and detects the height position of the upper surface of the workpiece held on the chuck table 36. . The height position detecting means 7 will be described with reference to FIGS.
Height position detecting means in the illustrated embodiment 7, gray te Ingumira 72 with multi-wavelength light source 71, such as a white light source, the multi-wavelength light source 71 in response to the wavelength of the detection light emitted spectrally in the Y-axis direction When, the first aberration-corrected focusing lens 73 for irradiating the upper surface of the wafer W as a workpiece held on the chuck table 36 collects the detection light split by the gray Te Ingumira 72 A second chromatic aberration correcting condensing lens 74 that condenses the detection light irradiated through the first chromatic aberration correcting condensing lens 73 and reflected by the upper surface of the wafer W held on the chuck table 36; And a light receiving means 75 having a plurality of CCD pixels arranged in a matrix in the Y-axis direction and the Z-axis direction for receiving the detection light condensed by the second chromatic aberration correction type condensing lens 74. An acousto-optic tunable filter that changes the refractive index between the second chromatic aberration correcting condensing lens 74 and the light receiving means 75 using a sound wave in the frequency range of 40 to 60 MHZ as indicated by a two-dot difference line. 76 may be arranged to select a specific wavelength.

Detection light emitted by the multi-wavelength light source 71 is split into a Y-axis direction by the gray Te Ingumira 72 as shown in FIG. 3, is held on the chuck table 36 through a first aberration-corrected focusing lens 73 The upper surface of the wafer W is irradiated with a predetermined incident angle α (see FIG. 2). In the embodiment shown in FIG. 3, the wavelength of the detection light is split in the Y-axis direction by the gray Te Ingumira 72 shows the range of 900nm from 700nm, for example. The range irradiated with detection light having a wavelength in the range of 700 nm to 900 nm is the diameter of the wafer W held on the chuck table 36 (the length of the workpiece in the Y-axis direction) in the illustrated embodiment. The range is set to cover.

The detection light having a specific wavelength in the detection light irradiated on the upper surface of the wafer W held on the chuck table 36 in this way will be described with reference to FIG.
Detection light having a specific wavelength is dispersed by a gray Te Ingumira 72 emitted from the multi-wavelength light source 71, a predetermined incident on the upper surface of the held wafer W on the chuck table 36 through a first aberration-corrected focusing lens 73 Irradiated with an angle α. The detection light having a specific wavelength irradiated on the upper surface of the wafer W is specularly reflected on the upper surface of the wafer W and is received by the light receiving means 75 through the second chromatic aberration correcting condensing lens 74. For example, when the height position of the wafer W is a position indicated by a one-dot chain line in FIG. 2, the detection light having a specific wavelength irradiated on the upper surface of the wafer W is reflected as indicated by the one-dot chain line, and the second Is received at point A of the light receiving means 75 through the chromatic aberration correcting condensing lens 74. On the other hand, when the height position of the wafer W is the position indicated by the two-dot chain line in FIG. 2, the detection light of the specific wavelength irradiated on the upper surface of the wafer W is reflected as indicated by the two-dot chain line and received. The light is received at point B of the light receiving means 75 through the second chromatic aberration correcting condensing lens 74. The data received by the light receiving means 75 in this way is sent to the control means described later. Then, the control means described later calculates the displacement h of the height position of the workpiece W based on the distance H between the points A and B detected by the light receiving means 75 (h = H / 2sin α). Therefore, when the reference value of the height position of the wafer W held on the chuck table 36 is the position indicated by the one-dot chain line in FIG. 2, the height position of the wafer W is the position indicated by the two-dot chain line in FIG. When it is displaced, it can be seen that it has been displaced downward by a height h. Accordingly, the height position of the wafer W can be obtained by detecting the amount of displacement from the set predetermined height position. In this way, the reflected light of the detection light of all wavelengths irradiated on the upper surface of the wafer W held on the chuck table 36 is received by the light receiving means 75, so that the total height position of the wafer W in the Y-axis direction can be simultaneously set. Can be detected.

Here, the light receiving means 75 of the height position detecting means 7 will be described with reference to FIG.
The light receiving means 75 shown in FIG. 4 is configured by an imaging device (CCD) including a plurality of pixels 751 arranged in a matrix in the Y-axis direction and the Z-axis direction. Y-axis direction of the light receiving means 75, in the illustrated embodiment is set in a range of 900nm from 700nm at a wavelength of the detection light is split in the Y-axis direction by the gray Te Ingumira 72. For this reason, in the illustrated embodiment, the height position in the Y-axis direction (Z-axis direction position) at a predetermined position in the X-axis direction of the wafer W held on the chuck table 36 can be detected simultaneously. Therefore, the control means is held on the chuck table 36 by sending the light receiving signal received by the light receiving means 75 of the height position detecting means 7 to the control means described later while moving the chuck table 36 in the X-axis direction. The height position (Z-axis direction position) of the wafer W in each of the X and Y coordinates can be obtained.

  Returning to FIG. 1, the description is continued. At the front end portion of the casing 521 constituting the laser beam irradiation means 52, an imaging means 8 for detecting a processing region to be laser processed by the laser beam irradiation means 52 is disposed. . In the illustrated embodiment, the imaging unit 8 includes, in addition to a normal imaging device (CCD) that captures an image with visible light, an infrared illumination unit that irradiates a workpiece with infrared rays, and an infrared ray that is irradiated by the infrared illumination units. And an imaging device (infrared CCD) that outputs an electrical signal corresponding to infrared rays captured by the optical system, and sends the captured image signal to a control means described later.

  The laser processing apparatus in the illustrated embodiment includes a control means 9 shown in FIG. The control means 9 includes a central processing unit (CPU) 91 that performs arithmetic processing according to a control program, a read-only memory (ROM) 92 that stores a control program, and a readable / writable random access memory (RAM) that stores arithmetic results and the like. 93, and an input interface 94 and an output interface 95. The input interface 94 of the control means 9 configured as described above includes the reading head 374b of the X-axis direction position detecting means 374, the reading head 384b of the Y-axis direction position detecting means 384, and the reading of the Z-axis direction position detecting means 55. Detection signals are input from the head 552, the light receiving means 75 of the height position detecting means 7, the imaging means 8, and the like. The output interface 95 outputs a control signal to the pulse motor 372, pulse motor 382, pulse motor 432, pulse motor 532, laser beam irradiation means 52, multi-wavelength light source 71 of the height position detector 7, and the like.

The laser beam machine in the illustrated embodiment is configured as described above, and the operation thereof will be described below.
FIG. 6 shows a perspective view of a wafer 10 as a workpiece to be laser processed. FIG. 6 is made of a silicon wafer, and a plurality of areas are partitioned by a plurality of streets 101 arranged in a lattice pattern on the surface 10a, and an optical device 102 such as an IC or LSI is formed in the partitioned areas. Is formed.

  In order to irradiate a laser beam along the street 101 of the wafer 10 and form a deteriorated layer along the street 101 inside the wafer 10, the wafer 10 is mounted on an annular frame F as shown in FIG. Adhere to dicing tape T. At this time, the wafer 10 adheres the front surface 20a side to the dicing tape T with the back surface 10b facing up.

  An embodiment of laser processing in which the above-described laser processing machine is used to irradiate a laser beam along the street 101 of the wafer 10 to form a deteriorated layer along the street 101 inside the wafer 10 will be described. Note that, when the altered layer is formed inside the wafer 10, if the thickness of the wafer 10 varies, the altered layer cannot be uniformly formed at a predetermined depth due to the refractive index as described above. Therefore, before the laser processing is performed, the height position of the wafer 10 held on the chuck table 36 is measured by the height position detection device 7 described above. That is, first, the dicing tape T side on which the wafer 10 is adhered is mounted on the chuck table 36 of the laser processing machine shown in FIG. 1 and the wafer 10 is sucked onto the chuck table 36 via the dicing tape T. Hold. Accordingly, the back surface 10b of the wafer 10 sucked and held on the chuck table 36 via the dicing tape T is on the upper side. The annular frame F on which the dicing tape T to which the wafer 10 is attached is attached is fixed by a clamp 362. The chuck table 36 that sucks and holds the wafer 10 in this way is positioned directly below the imaging means 8 by the processing feed means 37.

  When the chuck table 36 is positioned immediately below the imaging unit 8, the imaging unit 8 and the control unit 9 detect whether or not the street 101 formed in a predetermined direction of the wafer 10 is positioned in parallel with the X-axis direction. Perform alignment work. That is, the imaging unit 8 images a street 101 formed in a predetermined direction of the wafer 10 and sends the captured image signal to the control unit 9. The control means 9 determines whether or not the captured street 101 is parallel to the X-axis direction based on the image signal sent from the imaging means 8. If the street 101 is not parallel to the X-axis direction, the control table 9 rotates the chuck table 36. It is adjusted so that the street 101 is parallel to the X-axis direction. At this time, the surface 10a on which the street 101 of the wafer 10 is formed is positioned on the lower side. However, as described above, the imaging unit 8 generates an infrared illumination unit, an optical system for capturing infrared rays, and an electrical signal corresponding to infrared rays. Since the image pickup means including an output image pickup device (infrared CCD) or the like is provided, the street 101 can be picked up through the back surface 10b.

  When alignment is performed as described above, the wafer 10 on the chuck table 36 is positioned at the coordinate position shown in FIG. 8B shows a state in which the chuck table 36, that is, the wafer 10, is rotated 90 degrees from the state shown in FIG. 8A.

After performing the alignment, as described above, to move the chuck table 36 holding the wafer 10 below the height position detecting means 7, the height position detection means 7 multi-wavelength light source 71 is emitted from the gray Te Ingumira of The irradiation position of the detection light that is split in the Y-axis direction by 72 and condensed by the first chromatic aberration correcting condensing lens 73 is positioned at the measurement start position indicated by the one-dot chain line C in FIGS. . In this way, the X and Y coordinate values of the wafer 10 on the chuck table 36 positioned at the measurement start position and the Y coordinate value of the wavelength (700 nm to 900 nm) of the detection light emitted from the height position detecting means 7 are obtained. The relationship is set based on design values as shown in FIG. Accordingly, the relationship between each street 101 formed on the wafer 10 on the chuck table 36 and the wavelength of the detection light is set. For example, detection light having a wavelength of 710 nm corresponds to the street 101 located at the Y1 coordinate, detection light having a wavelength of 730 nm corresponds to the street 101 located at the Y2 coordinate, and 890 nm to the street 101 located at the Yn coordinate. Are set so as to correspond to the detection light of the wavelength. The relationship between each street 101 of the wafer 10 shown in FIG. 10 and the coordinate value of the wavelength of the detection light (700 nm to 900 nm) is stored in a random access memory (RAM) 93.

As described above, when the chuck table 36 holding the wafer 10 is positioned at the measurement start position, the height position detecting means 7 is operated to irradiate the wafer 10 held on the chuck table 36 with detection light. The chuck table 36 holding the wafer 10 is moved in the direction indicated by the arrow X1 in FIG. 9A, and the measurement end position indicated by the two-dot chain line D is detected as the height position as shown in FIG. 9B. When the irradiation position of the detection light emitted from the means 7 is reached, the operation of the height position detecting means 7 is stopped and the movement of the chuck table 36 holding the wafer 10 is stopped (height measuring step). During the height measurement process, a detection signal from the reading head 374 b of the X-axis direction position detection unit 374 is input to the control unit 9. Here, a light receiving signal received by the light receiving means 75 of the height position detecting means 7 at a predetermined movement position (position in the X-axis direction) of the chuck table 36 holding the wafer 10 will be described with reference to FIG. In the light receiving means 75, for example, the pixel 751 filled with black in FIG. 11 receives light corresponding to the detection light reflected on the upper surface of the wafer 10. Based on the received signal from the pixel 751, the control unit 9 determines the position (height position) in the Z-axis direction of the wavelength (710 nm) corresponding to the street 101 of the Y1 coordinate and the wavelength (730 nm) corresponding to the street 101 of the Y2 coordinate. ) In the Z-axis direction (height position),..., And the Z-axis direction position (height position) of the wavelength (890 nm) corresponding to the street 101 of the Yn coordinate. This height measurement step is performed from the position indicated by the one-dot chain line C in FIG. 10 (position shown in FIG. 9A) to the position indicated by the two-dot chain line D (position shown in FIG. 9B). Thus, the height position (Z-axis direction position) of each of the X and Y coordinates of the back surface (upper surface) corresponding to each street 101 formed on the wafer W held on the chuck table 36 can be obtained. Then, the control means 9 stores in the random access memory (RAM) 93 the height positions (Z-axis direction positions) in the X and Y coordinates of the back surface (upper surface) corresponding to the streets 101 thus obtained. . That is, if the surface position of the chuck table in FIG. 11 is (H0), the distance to the pixels filled in black corresponding to Y coordinates Y1, Y2,... Yn is (H), and FIG. ) And the X coordinate (X1, X2,... Xm) when moving the chuck table in the direction indicated by the arrow X1, the value of (h) obtained by h = H / 2sin α is the Z coordinate ( Z1, Z2,... Zm) are stored in a random access memory (RAM) 93. Thus, at a height position measuring device of the workpiece held on the chuck table in the illustrated embodiment, the first chromatic aberration is dispersed in the Y axis direction by the gray Te Ingumira 72 emitted from the multi-wavelength light source 71 Since the height position of the workpiece is detected by the detection light emitted through the correction type condensing lens 73, the height position of the workpiece can be detected simultaneously over a wide range.

  As described above, when the height measuring step is performed on the street 101 formed in the predetermined direction of the wafer 10, the chuck table 36 is rotated 90 degrees, and the wafer 10 held on the chuck table 36 is moved to FIG. It is positioned in the state shown in (b). Then, by performing the height measurement step, the height position (Z-axis direction position) of each street 101 formed in the direction orthogonal to the predetermined direction of the wafer 10 with respect to the X and Y coordinate values can be obtained. The height position (Z-axis direction position) of each street 101 with respect to the X and Y coordinate values is stored in a random access memory (RAM) 93.

  When the diameter of the wafer 10 as a workpiece is large, as shown in FIG. 12, the measurement range (E) in the Y-axis direction by the height position detecting means 7 is divided into a plurality of parts, and the height measuring step is performed. Performed multiple times to obtain the height position (Z-axis direction position) of each street 101 with respect to the X and Y coordinate values, and the height position (Z-axis direction position) of each street 101 with respect to the X and Y coordinate values is randomly accessed. (RAM) 93.

When the height measurement process is performed as described above, a deteriorated layer forming process is performed in which a deteriorated layer is formed along the street 101 inside the wafer 10.
In the deteriorated layer forming step, first, as shown in FIG. 13A, the chuck table 36 is moved to the laser beam irradiation region where the condenser 6 of the laser beam irradiation means 52 is located, and the wafer 10 held on the chuck table 36 is moved. One end of the predetermined street 101 (left end in FIG. 13A) is positioned directly below the condenser 6 of the laser beam irradiation means 52. The chuck table 36 is moved at a predetermined processing feed rate in the direction indicated by the arrow X1 in FIG. 13A while irradiating the wafer 10 with a pulse laser beam having a wavelength that is transmissive from the condenser 6. Then, as shown in FIG. 12B, when the other end of the street 101 (the right end in FIG. 13B) reaches the irradiation position of the condenser 6 of the laser beam irradiation means 52, the irradiation of the pulsed laser beam is stopped. At the same time, the movement of the chuck table 36 is stopped. In this deteriorated layer forming step, the condensing point P of the pulse laser beam is aligned with the middle portion of the wafer 10 in the thickness direction. In this deteriorated layer forming step, the control means 9 adjusts the focal point position based on the height position corresponding to the X and Y coordinate values in the street 101 of the wafer 10 stored in the random access memory (RAM) 103. The pulse motor 532 of the means 53 is controlled, and the condenser 6 is moved in the vertical direction corresponding to the height position on the street 101 of the wafer 10 as shown in FIG. As a result, an altered layer 110 is formed in the wafer 10 parallel to the back surface 10b (upper surface) at a predetermined depth from the back surface 10b (upper surface) as shown in FIG.

Note that the processing conditions in the deteriorated layer forming step are set as follows, for example.
Laser: YVO4 pulse laser Wavelength: 1064nm
Repetition frequency: 100 kHz
Pulse output: 2.5μJ
Condensing spot diameter: φ1μm
Processing feed rate: 100 mm / sec

  As described above, when the deteriorated layer forming step is executed along all the streets 101 extending in the predetermined direction of the wafer 10, the chuck table 36 is rotated by 90 degrees so that the chuck table 36 is rotated with respect to the predetermined direction. The altered layer forming step is performed along each street 101 extending at a right angle. In this way, if the above processing steps are executed along all the streets 101 formed on the wafer 10, the chuck table 36 holding the wafer 10 returns to the position where the wafer 10 is first sucked and held. At this point, the suction holding of the wafer 10 is released. The wafer 10 is transported to the dividing step by a transport means (not shown).

  As mentioned above, although the example which applied the height position detection apparatus of the workpiece hold | maintained at the chuck table by this invention to the laser processing machine was shown, this invention is various in processing the workpiece hold | maintained at the chuck table. It can be applied to a processing machine.

The perspective view of the laser processing machine equipped with the height position measuring apparatus of the workpiece hold | maintained at the chuck table comprised according to this invention. The block diagram which shows the structure of the height position detection means which comprises the height position measuring apparatus of the workpiece hold | maintained at the chuck table comprised according to this invention. FIG. 3 is an explanatory diagram illustrating a state in which detection light is irradiated to a workpiece held on a chuck table by a height position detection unit illustrated in FIG. 2. Explanatory drawing of the light-receiving means which comprises the height position detection means shown in FIG. The block diagram which shows the control means which comprises the height position measuring apparatus of the workpiece hold | maintained at the chuck table comprised according to this invention. The perspective view of the wafer as a to-be-processed object. The perspective view which shows the state which affixed the wafer shown in FIG. 6 on the surface of the dicing tape with which the cyclic | annular flame | frame was mounted | worn. FIG. 7 is an explanatory diagram showing a relationship with coordinate positions in a state where the wafer shown in FIG. 6 is held at a predetermined position of the chuck table of the laser beam machine shown in FIG. 1. Explanatory drawing of the height measurement process implemented by the height position measuring apparatus of the workpiece hold | maintained at the chuck table comprised according to this invention. Explanatory drawing which shows the relationship between the X and Y coordinate value of the wafer hold | maintained at the chuck table, and the Y coordinate value of the wavelength of the detection light irradiated from a height position detection means. Explanatory drawing which shows the state which the light-receiving means which comprises the height position detection means shown in FIG. 2 received detection light. Explanatory drawing of the height measurement process in case the diameter of the wafer as a workpiece is large. Explanatory drawing of the deteriorated layer formation process which forms a deteriorated layer in the wafer shown in FIG. 6 with the laser processing machine shown in FIG.

Explanation of symbols

1: Laser processing machine 2: Stationary base 3: Chuck table mechanism 36: Chuck table 37: X-axis direction moving means 374: X-axis direction position detecting means 38: First Y-axis direction moving means 384: Y-axis direction position Detection means 4: Laser beam irradiation unit support mechanism 42: Movable support base 43: Second Y-axis direction moving means 5: Laser beam irradiation unit 52: Laser beam irradiation means 53: Focusing point position adjusting means 55: Z-axis direction position detection means 6: condenser 7: height position detecting means 71: multi-wavelength light source 72: gray Te Ingumira 73: first aberration-corrected focusing lens 74: the second chromatic aberration correcting-gathering lens 75: light receiving means 8: Imaging means 9: Control means 10: Wafer (workpiece)

Claims (2)

A chuck table for holding a workpiece, a height position detecting means for detecting the upper surface height position of the workpiece held on the chuck table, and the chuck table and the height position detecting means are relatively X-axis direction moving means for moving in the X-axis direction and X-axis direction position detecting means for detecting the position of the chuck table in the X-axis direction. In the device
The high position detection means includes a multi-wavelength light source, and gray te Ingumira for splitting the Y-axis direction corresponding to the wavelength of the detection light multi-wavelength light source emits light perpendicular to the X-axis direction, the gray pos- sesses A first chromatic aberration correcting condensing lens that condenses the detection light dispersed by the mirror and irradiates the upper surface of the workpiece held on the chuck table, and irradiates through the first chromatic aberration correcting condensing lens. A second chromatic aberration correcting condensing lens that condenses the detection light reflected by the upper surface of the workpiece held by the chuck table, and the detection light condensed by the second chromatic aberration correcting condensing lens. A light receiving means having a plurality of CCD pixels in a matrix in the Y-axis direction and the Z-axis direction for receiving light, and a height position of the workpiece based on a detection signal from the X-axis direction position detecting means and the light receiving means. A control means to obtain, And Bei,
The detection light that is split in the Y-axis direction by the grating mirror and irradiated through the first chromatic aberration correcting condenser lens is set in a range corresponding to the length of the workpiece in the Y-axis direction,
The light receiving means includes a plurality of pixels arranged in a matrix in the X-axis direction and the Z-axis direction perpendicular to the Y-axis direction corresponding to the wavelength of the detection light dispersed in the Y-axis direction,
The control means obtains the position in the Z-axis direction in the X and Y coordinate values of the workpiece based on the detection signals from the X-axis direction position detection means and the light receiving means.
An apparatus for measuring a height position of a workpiece held on a chuck table.   The apparatus for measuring a height position of a workpiece held on a chuck table according to claim 1, wherein the multi-wavelength light source is a white light source.

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