JP2021028082A - Laser processing device and method for processing workpiece - Google Patents

Abstract

To provide a laser processing device which can easily and highly accurately adjust a positional relation between a region irradiated with a laser beam for processing and a region irradiated with a laser beam for measurement.SOLUTION: A laser processing device includes: a chuck table for holding a workpiece by a holding surface; a movement unit for moving the chuck table; a laser irradiation unit for irradiating the workpiece held by the chuck table with a laser beam for processing for processing the workpiece; and a height measurement unit for measuring the height of the workpiece by irradiating the workpiece held by the chuck table with the laser beam for measurement and detecting the laser beam for measurement reflected by the workpiece, in which the laser irradiation unit includes an irradiation position adjustment unit for moving the region irradiated with the laser beam for processing.SELECTED DRAWING: Figure 1

Description

The present invention relates to a laser processing apparatus that processes a work piece by irradiating a laser beam, and a method for processing a work piece using the laser processing device.

In the device chip manufacturing process, wafers in which devices such as ICs (Integrated Circuits) and LSIs (Large Scale Integration) are formed in a plurality of regions partitioned by scheduled division lines (streets) are used. By dividing this wafer along the planned division line, a plurality of device chips each including a device can be obtained.

A cutting apparatus including a chuck table for holding the wafer on a holding surface and a cutting unit equipped with an annular cutting blade for cutting the wafer is used for dividing the wafer. By rotating the cutting blade and cutting into the wafer held by the chuck table, the wafer is cut and divided into a plurality of device chips.

Further, in recent years, a method of dividing a wafer by irradiating a laser beam has also been proposed. For example, by irradiating the wafer with a laser beam along a planned division line, a modified region (modified layer) is formed inside the wafer. The region where this modified layer is formed is more brittle than the other regions of the wafer. Therefore, when an external force is applied to the wafer on which the reforming layer is formed along the planned division line, the wafer breaks along the planned division line and is divided into a plurality of chips (see Patent Document 1).

In order to properly divide the wafer, it is preferable that the modified layer is formed along the planned division line so that the distance from the surface of the wafer to the modified layer is constant. However, the wafer on which the modified layer is formed may have in-plane variations in thickness. In addition, the holding surface of the chuck table may be slightly tilted unintentionally.

In such a case, if the modified layer is formed on the wafer while keeping the height of the focusing point of the laser beam constant, the distance from the surface of the wafer to the modified layer (the depth at which the modified layer is formed) There will be variation. When an external force is applied to the wafer in a state where the depth of the reformed layer formed on the wafer varies, phenomena such as the breaking position of the wafer shifting and the breaking of the wafer not occurring occur, and the wafer is appropriately divided. It may not be done.

Therefore, when forming the modified layer on the wafer, it is possible to irradiate a processing laser beam for forming the modified layer on the wafer and a measuring laser beam for measuring the height of the wafer. Laser processing equipment may be used (see Patent Document 2). By using this laser processing apparatus, it is possible to detect the height of the surface of the wafer and adjust the height of the focusing point of the processing laser beam based on the detected height of the surface of the wafer. As a result, the reformed layer is formed at a constant depth position of the wafer even when the thickness of the wafer varies or the chuck table is tilted.

JP-A-2002-192370 Japanese Unexamined Patent Publication No. 2005-193286

As described above, when the modified layer is formed on the wafer while measuring the height of the wafer, the processing laser beam is scanned so that the processing laser beam and the measurement laser beam are scanned on the same straight line. And it is necessary to precisely adjust the irradiation position of the laser beam for measurement. However, for example, in the method of manually and mechanically adjusting the mounting position and angle of the measuring instrument that irradiates the measurement laser beam, the adjustment work is troublesome and the adjustment accuracy is limited.

In particular, in recent years, the miniaturization of device chips has progressed, and the distance between devices formed on the wafer (width of the planned division line) has also become narrower. Therefore, higher accuracy is also required for adjusting the irradiation positions of the processing laser beam and the measuring laser beam.

The present invention has been made in view of such a problem, and a laser capable of easily and highly accurately adjusting the positional relationship between a region irradiated with a processing laser beam and a region irradiated with a measuring laser beam. An object of the present invention is to provide a processing apparatus and a processing method for a workpiece using the laser processing apparatus.

According to one aspect of the present invention, the chuck table that holds the workpiece on the holding surface, the chuck table in the first direction parallel to the holding surface, and the first direction parallel to the holding surface. A moving unit that moves along a second direction perpendicular to the direction, and a laser irradiation unit that irradiates the workpiece held by the chuck table with a laser beam for processing to process the workpiece. The height at which the height of the workpiece is measured by irradiating the workpiece held by the chuck table with a laser beam for measurement and detecting the laser beam for measurement reflected by the workpiece. The moving unit comprises a measuring unit, and the moving unit moves the chuck table along the first direction when the workpiece is processed by the processing laser beam, and the laser irradiation unit is provided. An irradiation position adjusting unit for moving the area irradiated with the processing laser beam along the second direction is provided, and the area irradiated with the measurement laser beam is irradiated with the processing laser beam. The irradiation position adjusting unit is positioned behind the region in the traveling direction of the chuck table when the workpiece is processed, and the irradiation position adjusting unit is the region irradiated with the processing laser beam and the measurement laser beam. Provided is a laser processing apparatus capable of adjusting the position of the region irradiated with the processing laser beam in the second direction so that the difference from the region irradiated with the laser beam in the second direction is reduced.

Further, according to another aspect of the present invention, there is a method of processing a work piece by using a laser processing device, and the laser processing device holds the work piece on a holding surface. A chuck table and a moving unit that moves the chuck table along a first direction parallel to the holding surface and a second direction parallel to the holding surface and perpendicular to the first direction. A laser irradiation unit that irradiates the work piece held by the chuck table with a processing laser beam for processing the work piece, and a measurement laser beam on the work piece held by the chuck table. A height measuring unit that measures the height of the work piece by irradiating and detecting the measurement laser beam reflected by the work piece, a region irradiated with the work laser beam, and the measurement. The laser irradiation unit includes a control unit having a storage unit for storing the amount of deviation from the region irradiated with the laser beam for processing in the second direction, and the laser irradiation unit covers the region irradiated with the laser beam for processing. An irradiation position adjusting unit for moving along the second direction is provided, and a deviation amount storage step for storing the deviation amount in the storage unit and the deviation amount storage step stored in the storage unit after the execution of the deviation amount storage step are performed. Based on the amount of deviation, the region to be irradiated with the processing laser beam is moved along the second direction by the irradiation position adjusting unit, and the region to be irradiated with the processing laser beam and the measurement laser beam are moved. After performing the irradiation position adjustment step for reducing the difference from the area irradiated with the laser in the second direction and the irradiation position adjustment step, the chuck table is moved along the first direction for the measurement. A modified layer that irradiates the workpiece with a laser beam to measure the height of the workpiece and irradiates the workpiece with the laser beam for processing to form a modified layer on the workpiece. It has a forming step, and in the modified layer forming step, the processing laser beam irradiated to the region is based on the height of the region irradiated with the measurement laser beam of the workpiece. A method for processing a work piece for adjusting the height of a condensing point is provided.

In the laser processing apparatus according to one aspect of the present invention, the laser irradiation unit is provided with an irradiation position adjusting unit that moves a region irradiated with a processing laser beam along a second direction. Then, this irradiation position adjusting unit adjusts the position of the region where the processing laser beam is irradiated, so that the second region where the processing laser beam is irradiated and the region where the measurement laser beam is irradiated is second. Close the difference in direction. As a result, the alignment between the region irradiated with the processing laser beam and the region irradiated with the measurement laser beam can be easily and highly accurately performed.

It is a perspective view which shows the laser processing apparatus. It is a perspective view which shows the workpiece held by a chuck table. It is a partial cross-sectional front view which shows typically the laser irradiation unit and a pair of height measurement units. It is a top view which shows the region which is irradiated with a laser beam for processing and the region which is irradiated with a laser beam for measurement. FIG. 5 (A) is a plan view showing how the positional deviation between the irradiation region of the processing laser beam and the irradiation region of one of the measurement laser beams is corrected, and FIG. 5 (B) is a plan view of the processing laser beam. It is a top view which shows how the positional deviation between an irradiation area and the irradiation area of the other measurement laser beam is corrected.

Hereinafter, embodiments according to one aspect of the present invention will be described with reference to the accompanying drawings. First, a configuration example of the laser processing apparatus according to the present embodiment will be described. FIG. 1 is a perspective view showing a laser processing apparatus 2.

The laser processing apparatus 2 includes a base 4 that supports each component constituting the laser processing apparatus 2. The surface (upper surface) 4a of the base 4 is formed substantially parallel to the X-axis direction (machining feed direction, left-right direction, first horizontal direction) and Y-axis direction (indexing feed direction, front-back direction, second horizontal direction). ing. Further, behind the base 4, a rectangular parallelepiped support structure 6 is arranged along the Z-axis direction (vertical direction, vertical direction).

A moving unit (moving mechanism) 8 is provided on the surface 4a of the base 4. The moving unit 8 includes a Y-axis moving unit (Y-axis moving mechanism) 10 and an X-axis moving unit (X-axis moving mechanism) 20.

The Y-axis moving unit 10 includes a pair of Y-axis guide rails 12 arranged substantially parallel to the Y-axis direction on the surface 4a of the base 4. A plate-shaped Y-axis moving table 14 is mounted on the pair of Y-axis guide rails 12 so as to be slidable in the Y-axis direction along the pair of Y-axis guide rails 12.

A nut portion (not shown) is provided on the back surface (lower surface) side of the Y-axis moving table 14. A Y-axis ball screw 16 arranged substantially parallel to the pair of Y-axis guide rails 12 is screwed into the nut portion. Further, a Y-axis pulse motor 18 for rotating the Y-axis ball screw 16 is connected to one end of the Y-axis ball screw 16. When the Y-axis ball screw 16 is rotated by the Y-axis pulse motor 18, the Y-axis moving table 14 moves in the Y-axis direction along the pair of Y-axis guide rails 12.

The X-axis moving unit 20 includes a pair of X-axis guide rails 22 arranged substantially parallel to the X-axis direction on the surface (upper surface) side of the Y-axis moving table 14. A plate-shaped X-axis moving table 24 is mounted on the pair of X-axis guide rails 22 so as to be slidable in the X-axis direction along the pair of X-axis guide rails 22.

A nut portion (not shown) is provided on the back surface (lower surface) side of the X-axis moving table 24. An X-axis ball screw 26 arranged substantially parallel to the pair of X-axis guide rails 22 is screwed into the nut portion. Further, an X-axis pulse motor 28 for rotating the X-axis ball screw 26 is connected to one end of the X-axis ball screw 26. When the X-axis ball screw 26 is rotated by the X-axis pulse motor 28, the X-axis moving table 24 moves in the X-axis direction along the pair of X-axis guide rails 22.

On the surface (upper surface) side of the X-axis moving table 24, a chuck table (holding table) 30 for holding the workpiece 11 processed by the laser processing apparatus 2 is arranged. The upper surface of the chuck table 30 constitutes a holding surface 30a for holding the workpiece 11. The holding surface 30a is formed substantially parallel to the horizontal direction (XY plane direction), and is used as a suction source (not shown) such as an ejector via a suction path (not shown) formed inside the chuck table 30. It is connected.

The moving unit 8 moves the chuck table 30 along a direction parallel to the holding surface 30a (XY plane direction). Specifically, the X-axis moving unit 20 moves the chuck table 30 along the first direction (X-axis direction) parallel to the holding surface 30a, and the Y-axis moving unit 10 moves the chuck table 30 with the holding surface 30a. It is moved along a second direction (Y-axis direction) that is parallel and perpendicular to the first direction.

The moving unit 8 includes a Y-axis detection unit (not shown) that detects the position of the Y-axis moving table 14 in the Y-axis direction and an X-axis detecting unit that detects the position of the X-axis moving table 24 in the X-axis direction. (Not shown) is provided. By detecting the positions of the X-axis moving table 24 and the Y-axis moving table 14 by the X-axis detecting unit and the Y-axis detecting unit, the positions (moving distances) of the chuck table 30 in the X-axis direction and the Y-axis direction are specified. To.

Further, the chuck table 30 is connected to a rotary drive source (not shown) such as a motor. This rotation drive source rotates the chuck table 30 around a rotation axis substantially parallel to the Z-axis direction. Further, a plurality of clamps 32 are provided around the chuck table 30 to grip and fix the annular frame 19 that supports the workpiece 11.

A columnar support arm 40 projecting forward from the support structure 6 is fixed to the support structure 6 arranged behind the base 4. A laser irradiation unit 42 that irradiates a laser beam is arranged at the tip of the support arm 40. The work piece 11 is processed by irradiating the work piece 11 held by the chuck table 30 with the laser beam emitted from the laser irradiation unit 42.

A pair of height measuring units (height measuring instruments) 44, 46 for measuring the position (height) of the workpiece 11 held by the chuck table 30 in the Z-axis direction at a position adjacent to the laser irradiation unit 42. Is provided. The pair of height measuring units 44 and 46 are arranged so as to sandwich the laser irradiation unit 42 in the X-axis direction.

The height measuring unit 44 is arranged on one side of the laser irradiation unit 42 (one end side of the X axis), and the height measuring unit 46 is located on the other side of the laser irradiation unit 42 (other than the X axis). It is located on the end side). That is, the laser irradiation unit 42, the height measurement unit 44, and the height measurement unit 46 are arranged on the same straight line along the X-axis direction.

Further, an imaging unit (camera) 48 for imaging the workpiece 11 and the like held by the chuck table 30 is fixed to the support arm 40. For example, based on the image acquired by the imaging unit 48, the workpiece 11 held by the chuck table 30 is aligned with the laser irradiation unit 42 and the height measuring units 44 and 46.

A display unit (display unit) 50 for displaying various information related to the processing of the workpiece 11 by the laser processing apparatus 2 is provided on the front side of the laser processing apparatus 2. For example, the display unit 50 is composed of a touch panel as a user interface. In this case, the display unit 50 displays an operation screen for operating the laser machining apparatus 2, an image of the workpiece 11 being machined, and the like. The operator of the laser processing apparatus 2 operates the display unit 50 to input processing conditions and the like into the laser processing apparatus 2.

Each component (moving unit 8, chuck table 30, clamp 32, laser irradiation unit 42, height measuring units 44, 46, imaging unit 48, display unit 50, etc.) constituting the laser processing device 2 is a laser processing device 2. Is connected to a control unit (control unit) 60 that controls the above. The control unit 60 is composed of a computer or the like, and controls the operation of each component of the laser processing apparatus 2.

FIG. 2 is a perspective view showing the workpiece 11 held by the chuck table 30. The workpiece 11 is, for example, a silicon wafer formed in a disk shape, and includes a front surface 11a and a back surface 11b. Further, the workpiece 11 is divided into a plurality of regions by a plurality of scheduled division lines (streets) 13 arranged in a grid pattern so as to intersect each other, and ICs are respectively on the surface 11a side of the plurality of regions. (Integrated Circuit), LSI (Large Scale Integration) and other devices 15 are formed.

A circular tape 17 made of a flexible resin or the like and having a diameter larger than that of the workpiece 11 is attached to the back surface 11b side of the workpiece 11. The tape 17 is a protective member that protects the back surface 11b side of the workpiece 11 when the workpiece 11 is processed. Further, an annular frame 19 having a circular opening 19a having a diameter larger than that of the workpiece 11 is attached to the outer peripheral portion of the tape 17 at the central portion. When the tape 17 is attached to the workpiece 11 and the frame 19, the workpiece 11 is supported by the frame 19 via the tape 17 inside the opening 19a.

There are no restrictions on the material, shape, structure, size, etc. of the workpiece 11. For example, the workpiece 11 may be a wafer made of a material other than silicon (GaAs, SiC, InP, GaN, etc.), ceramics, resin, metal, or the like. Further, there are no restrictions on the type, quantity, shape, structure, size, arrangement, etc. of the device formed on the workpiece 11, and the device may not be formed on the workpiece 11.

When the workpiece 11 is machined by the laser machining apparatus 2, the workpiece 11 is arranged on the chuck table 30 via the tape 17. At this time, the workpiece 11 is arranged so that the front surface 11a side is exposed upward and the back surface 11b side faces the holding surface 30a (see FIG. 1) of the chuck table 30. Further, the frame 19 is gripped and fixed by a plurality of clamps 32 (see FIG. 1). In this state, when a negative pressure of the suction source is applied to the holding surface 30a of the chuck table 30, the workpiece 11 is sucked and held by the chuck table 30 via the tape 17.

Then, the workpiece 11 is processed by the laser beam emitted from the laser irradiation unit 42. For example, by irradiating the workpiece 11 with a laser beam from the laser irradiation unit 42 along the scheduled division line 13, a region modified (altered) inside the workpiece 11 (modified layer (altered layer)). 11c, see FIG. 3) is formed along the scheduled division line 13.

When the modified layer 11c is formed on the workpiece 11, cracks (cracks) extending from the modified layer 11c toward the front surface 11a or the back surface 11b of the workpiece 11 in the thickness direction of the workpiece 11 are generated. The cracks are formed so as to reach, for example, the front surface 11a and the back surface 11b of the workpiece 11 from the modified layer 11c.

The region where the modified layer 11c of the workpiece 11 is formed becomes more brittle than the other regions of the workpiece 11. Therefore, when an external force is applied to the workpiece 11 on which the modified layer 11c is formed along the planned division line 13, the workpiece 11 breaks along the planned division line 13 starting from the modified layer 11c and is divided. Will be done. That is, the modified layer 11c functions as a division starting point (division trigger) of the workpiece 11.

When the modified layer 11c is formed on the work piece 11 by irradiation with a laser beam, the wavelength of the laser beam is such that the laser beam passes through the work piece 11 (has transparency to the work piece 11). Set. Further, other irradiation conditions (power, spot diameter, repetition frequency, etc.) of the laser beam are set so that the modified layer 11c is formed inside the workpiece 11 by multiphoton absorption.

When forming the modified layer 11c on the workpiece 11, first, the length direction of one scheduled division line 13 set on the workpiece 11 is set to coincide with the machining feed direction (X-axis direction). , Rotate the chuck table 30. Further, the focusing point of the laser beam emitted from the laser irradiation unit 42 is positioned on an extension line of the one scheduled division line 13. The height of the focusing point of the laser beam is positioned below the front surface 11a of the workpiece 11 and above the back surface 11b.

In this state, the chuck table 30 is moved along the machining feed direction (X-axis direction) while irradiating the laser beam from the laser irradiation unit 42 (machining feed). As a result, the workpiece 11 held by the chuck table 30 and the laser irradiation unit 42 move relatively, and the laser beam is irradiated along one scheduled division line 13. As a result, the modified layer 11c is formed inside the workpiece 11 along one scheduled division line 13.

After that, by repeating the same operation, the modified layer 11c is formed along all the planned division lines 13 set on the workpiece 11. The modified layer 11c may be formed in two or more stages in the thickness direction of the workpiece 11 depending on the thickness, material, and the like of the workpiece 11.

After that, for example, by applying an external force to the workpiece 11, the workpiece 11 is divided along the scheduled division line 13. The application of an external force to the workpiece 11 is performed, for example, by pulling the tape 17 outward in the radial direction and expanding the tape 17. In this case, as the tape 17, a tape (expanded tape) that can be expanded by applying an external force is used.

In order to appropriately divide the workpiece 11, the modified layer 11c is formed along the planned division line 13 so that the distance from the surface 11a of the workpiece 11 to the modified layer 11c is constant. It is preferable to be done. However, the workpiece 11 on which the modified layer 11c is formed may have in-plane variations in thickness. In addition, the holding surface 30a of the chuck table 30 may be slightly tilted unintentionally.

In such a case, when the modified layer 11c is formed on the workpiece 11 while keeping the height of the focusing point of the laser beam constant, the distance from the surface 11a of the workpiece 11 to the modified layer 11c (modification). The depth at which the layer 11c is formed) varies. Then, when an external force is applied to the work piece 11 in a state where the depth of the modified layer 11c formed on the work piece 11 varies, the break position of the work piece 11 shifts, and the work piece 11 breaks. There is a risk that the workpiece 11 may not be properly divided due to a phenomenon such as not occurring.

Therefore, when the modified layer 11c is formed on the workpiece 11, the position (height) of the workpiece 11 in the Z-axis direction is measured, and the height of the focusing point of the laser beam is based on the measurement result. It is preferable to irradiate the workpiece 11 with a laser beam while adjusting the height. The height of the workpiece 11 can be measured by using a pair of height measuring units 44, 46 installed adjacent to the laser irradiation unit 42.

FIG. 3 is a partial cross-sectional front view schematically showing the laser irradiation unit 42 and the pair of height measuring units 44 and 46. In addition, in FIG. 3, a part of the component elements of the laser processing apparatus 2 is shown by a block.

The laser irradiation unit 42 includes a laser oscillator 80 that pulse-oscillates a laser beam. As the laser oscillator 80, for example a YAG laser, YVO ₄ laser, YLF laser or the like is used. The laser beam pulse-oscillated by the laser oscillator 80 passes through the irradiation position adjusting unit 82 and is irradiated to the mirror 84. Then, the laser beam reflected by the mirror 84 is incident on the processing head 86. The configuration and function of the irradiation position adjusting unit 82 will be described later.

The processing head 86 includes a housing 88 formed in a hollow columnar shape. A lens holder 90 that supports and accommodates the condenser lens 92 is provided inside the housing 88. The laser beam reflected by the mirror 84 is incident on the condenser lens 92 and is focused by the condenser lens 92 at a predetermined position.

A drive unit 94 that moves the lens holder 90 together with the condenser lens 92 along the Z-axis direction is connected to the lens holder 90. For example, the drive unit 94 is composed of an actuator (typically a piezo actuator). The drive unit 94 controls the position (height) of the condenser lens 92 in the Z-axis direction, and adjusts the height of the condenser point of the laser beam.

The laser beam irradiated from the laser irradiation unit 42 in this way is used as a processing laser beam 96 for processing the workpiece 11 held by the chuck table 30. When the processing laser beam 96 is focused inside the workpiece 11, the modified layer 11c is formed inside the workpiece 11.

A pair of height measuring units 44, 46 are provided on both sides of the processing head 86. The pair of height measuring units 44 and 46 are arranged so as to sandwich the machining head 86 in the X-axis direction, and the machining head 86 and the height measuring units 44 and 46 are arranged on the same straight line along the X-axis direction. Has been done. The height measuring units 44 and 46 may be fixed to the processing head 86 or may be fixed to the support arm 40 (see FIG. 1).

The height measuring units 44 and 46 each measure the position (height) of the workpiece 11 held by the chuck table 30 in the Z-axis direction in a non-contact manner. For example, the height measuring units 44 and 46 are composed of a laser displacement sensor or the like that measures the height of the workpiece 11 by irradiating the laser beam.

In the following, as an example, a case where the height measuring units 44 and 46 are reflection type laser displacement sensors will be described. Each of the height measuring units 44 and 46 includes a light source (light emitting unit) for irradiating a laser beam and a light receiving element (light receiving unit) for receiving the laser beam reflected by the workpiece 11.

The height measuring unit 44 irradiates the measuring laser beam 98 toward the workpiece 11, and receives the measuring laser beam 98 reflected by the surface 11a of the workpiece 11. Then, the height measuring unit 44 measures the height of the surface 11a of the workpiece 11 based on the intensity (light receiving amount) of the received measurement laser beam 98.

Similarly, the height measuring unit 46 irradiates the measuring laser beam 100 toward the workpiece 11, and receives the measuring laser beam 100 reflected by the surface 11a of the workpiece 11. Then, the height measuring unit 46 measures the height of the surface 11a of the workpiece 11 based on the intensity (light receiving amount) of the received measurement laser beam 100.

When the modified layer 11c is formed on the workpiece 11, the workpiece 11 is irradiated with the processing laser beam 96 while measuring the height of the workpiece 11 by one of the height measuring units 44 and 46. To do. At this time, the height of the workpiece 11 is measured so that the laser beams 98 and 100 for measurement are irradiated to the predetermined region of the workpiece 11 before the laser beam 96 for machining is irradiated to the predetermined region. It is done in.

Specifically, when the chuck table 30 moves in the direction indicated by the arrow A during processing of the workpiece 11, the laser irradiation unit 42 irradiates the processing laser beam 96 and the laser irradiation unit 42 (processing head). The laser beam 98 for measurement is irradiated from the height measuring unit 44 provided on the rear side (right side in FIG. 3) of the chuck table 30 in the traveling direction with respect to 86). Therefore, the region irradiated with the measurement laser beam 98 is positioned on the rear side in the traveling direction of the chuck table 30 with respect to the region irradiated with the processing laser beam 96.

As a result, the measurement laser beam 98 is irradiated along the planned division line 13 (see FIG. 2) of the workpiece 11, and the processing laser beam 96 is irradiated along the irradiated region of the measurement laser beam 98. Is irradiated. That is, the processing laser beam 96 irradiates the workpiece 11 while following the measurement laser beam 98.

On the other hand, when the chuck table 30 moves in the direction indicated by the arrow B during processing of the workpiece 11, the laser beam 96 for processing is irradiated from the laser irradiation unit 42, and the laser irradiation unit 42 (processing head 86) emits the laser beam 96. The laser beam 100 for measurement is irradiated from the height measuring unit 46 provided on the rear side (left side in FIG. 3) of the chuck table 30 in the traveling direction. Therefore, the region irradiated with the measurement laser beam 100 is positioned on the rear side in the traveling direction of the chuck table 30 with respect to the region irradiated with the processing laser beam 96.

As a result, the measurement laser beam 100 is irradiated along the scheduled division line 13 (see FIG. 2) of the workpiece 11, and the processing laser beam 96 is irradiated along the irradiated region of the measurement laser beam 100. Is irradiated. That is, the processing laser beam 96 irradiates the workpiece 11 while following the measurement laser beam 100.

Then, when the processing laser beam 96 is irradiated to the region where the height is measured by the height measuring units 44 and 46 (the region where the measurement laser beams 98 and 100 are irradiated), the work piece 11 is measured. The height of the focusing point of the processing laser beam 96 is sequentially adjusted by the drive unit 94 based on the height of the laser beam 96. As a result, the height difference between the surface 11a of the workpiece 11 and the condensing point of the processing laser beam 96 is kept constant, and the modified layer 11c is formed at a predetermined depth position of the workpiece 11. Laser.

Here, in order to appropriately adjust the height of the focusing point of the processing laser beam 96 based on the height of the workpiece 11 measured by the height measuring units 44 and 46, the measurement laser beam It is necessary that the path irradiated with 98, 100 and the path irradiated with the processing laser beam 96 match. Therefore, when the height measuring units 44 and 46 are mounted, the region irradiated with the processing laser beam 96 and the region irradiated with the measuring laser beams 98 and 100 are arranged along the X-axis direction. In addition, the mounting positions and angles of the height measuring units 44 and 46 are adjusted.

However, in the method of manually and mechanically adjusting the mounting positions of the height measuring units 44 and 46, the adjustment work is troublesome and the adjustment accuracy is limited. In particular, in recent years, the miniaturization of device chips has progressed, and the distance between the devices 15 formed on the workpiece 11 (the width of the scheduled division line 13) has become narrower. Therefore, higher accuracy is also required for adjusting the irradiation region of the measurement laser beams 98 and 100.

Here, in the laser processing apparatus 2 according to the present embodiment, as shown in FIG. 3, the irradiation position adjusting unit for moving the region irradiated with the processing laser beam 96 to the laser irradiation unit 42 along the Y-axis direction. 82 is provided. Then, the irradiation position adjusting unit 82 adjusts the region to be irradiated with the processing laser beam 96, so that the region to be irradiated with the processing laser beam 96 and the region to be irradiated with the measurement laser beams 98 and 100 Reduce the difference in the Y-axis direction. As a result, the alignment between the region irradiated with the processing laser beam 96 and the region irradiated with the measuring laser beams 98 and 100 can be easily and highly accurately performed.

The irradiation position adjusting unit 82 is provided in the optical path of the processing laser beam 96 (between the laser oscillator 80 and the mirror 84 in FIG. 3), and is a region (condensing point) where the processing laser beam 96 is irradiated. Controls the position of the laser in the Y-axis direction. For example, the irradiation position adjusting unit 82 is composed of a laser scanning unit provided with a spatial light modulator (SLM), and the spatial light modulator controls the position of a region irradiated with the processing laser beam 96. ..

Examples of the spatial light modulator that can be used in the irradiation position adjusting unit 82 include LCOS-SLM (Liquid Crystal On Silicon-Spatial Light Modulator), acoustic optical element (AOD: Acousto-Optic Deflector), and the like. However, the configuration of the irradiation position adjusting unit 82 is not limited as long as the optical path of the processing laser beam 96 can be controlled and the position of the region irradiated with the processing laser beam 96 in the Y-axis direction can be controlled.

The irradiation of the processing laser beam 96 by the laser irradiation unit 42 and the irradiation of the measurement laser beams 98 and 100 by the height measuring units 44 and 46 are controlled by the control unit 60. The laser oscillator 80, the irradiation position adjusting unit 82, the driving unit 94, and the height measuring units 44 and 44 included in the laser irradiation unit 42 are connected to the control unit 60, respectively, and the operation is controlled by the control unit 60. Laser.

The control unit 60 includes a processing unit 62 that performs processing such as various calculations required for controlling the laser processing apparatus 2, and a storage unit 64 that stores various data, programs, and the like used for processing by the processing unit 62. Be prepared. The processing unit 62 is configured to include a processor such as a CPU (Central Processing Unit), and the storage unit 64 is configured to include a memory such as a RAM (Random Access Memory). The processing unit 62 and the storage unit 64 are connected to each other via a bus.

Further, FIG. 3 shows the functional structure of the processing unit 62. The processing unit 62 controls the oscillation control unit 66 that controls the oscillation of the laser beam by the laser oscillator 80, and the irradiation position control unit 82 that controls the position of the region where the processing laser beam 96 is irradiated by controlling the irradiation position adjustment unit 82. 68, a height control unit 70 that adjusts the heights of the lens holder 90 and the condenser lens 92 by controlling the drive unit 94, and controls the height of the condenser point of the processing laser beam 96, and the workpiece 11 A selection unit 72 for selecting and operating one of the height measuring units 44 and 46 used for measuring the height of the laser is provided.

By controlling the laser irradiation unit 42 and the height measurement units 44 and 46 by the control unit 60, the position shift between the irradiation position of the processing laser beam 96 and the irradiation position of the measurement laser beams 98 and 100 in the Y-axis direction. Is reduced (misalignment correction). Hereinafter, a specific example of a processing method of the work piece, in which the deviation correction is performed and then the modified layer 11c is formed on the work piece 11, will be described.

When performing the deviation correction, first, the difference (deviation amount) in the Y-axis direction between the region irradiated with the processing laser beam 96 and the region irradiated with the measurement laser beams 98 and 100 is measured. Then, the measured deviation amount is stored in the storage unit 64 of the control unit 60 (deviation amount storage step).

FIG. 4 is a plan view showing a region irradiated with the processing laser beam 96 and a region irradiated with the measurement laser beams 98 and 100. The irradiation region 96a in FIG. 4 is a region (beam spot of the processing laser beam 96) on which the processing laser beam 96 is irradiated. The irradiation regions 98a and 100a are regions where the measurement laser beams 98 and 100 are irradiated (beam spots of the measurement laser beams 98 and 100). Further, ΔY ₁ indicates the difference in position (displacement amount) between the irradiation region 96a and the irradiation region 98a in the Y-axis direction, and ΔY ₂ indicates the difference in position (displacement amount) between the irradiation region 96a and the irradiation region 100a in the Y-axis direction. ) Is shown.

In the processing method of the workpiece according to the present embodiment, first, the deviation amounts ΔY ₁ and ΔY ₂ are measured. There is no limitation on the method of measuring the deviation amounts ΔY ₁ and ΔY ₂ , but for example, the test member (test wafer) 21 is processed by the processing laser beam 96, and the surface 21a of the test member 21 is processed by the height measuring units 44 and 46. It is carried out by measuring the height of the laser.

Specifically, first, the test member 21 is held by the chuck table 30 (see FIGS. 1 and 2). At this time, the test member 21 is arranged on the chuck table 30 so that the surface 21a is exposed upward. The test member 21 is a test member used for measuring the amount of deviation. The material and shape of the test member 21 are not limited, and for example, a member having the same material and shape as the workpiece 11 can be used.

Next, the chuck table 30 is moved along the X-axis direction while irradiating the processing laser beam 96 from the laser irradiation unit 42 to the surface 21a side of the test member 21 (processing feed). As a result, the processing laser beam 96 is linearly (striped) irradiated to the surface 21a side of the test member 21. The irradiation region 96a shown in FIG. 4 corresponds to the region of the surface 21a of the test member 21 where the processing laser beam 96 is irradiated.

At this time, the irradiation conditions of the processing laser beam 96 are set so that the processing marks 21b are formed on the surface 21a side of the test member 21. For example, the irradiation conditions of the processing laser beam 96 are set so that the test member 21 is subjected to ablation processing when the processing laser beam 96 is irradiated to the test member 21. Therefore, when the test member 21 is irradiated with the processing laser beam 96, linear (strip-shaped) processing marks 21b are formed on the surface 21a side of the test member 21.

Next, the chuck table 30 is moved along the X-axis direction without changing the position of the chuck table 30 in the Y-axis direction, and the test member 21 on which the machining marks 21b are formed is moved to the height measuring units 44 and 46. Place it on the lower side. Then, the measurement laser beams 98 and 100 are irradiated from the height measuring units 44 and 46 to the surface 21a of the test member 21, respectively. The irradiation regions 98a and 100a in FIG. 4 correspond to regions of the surface 21a of the test member 21 on which the measurement laser beams 98 and 100 are irradiated, respectively.

Here, when there is no positional deviation between the irradiation region 96a and the irradiation regions 98a, 100a in the Y-axis direction (ΔY ₁ = 0, ΔY ₂ = 0), or when the positional deviation is within a predetermined range, irradiation is performed. The regions 98a and 100a overlap with the processing marks 21b, and the measuring laser beams 98 and 100 are irradiated on the processing marks 21b. Then, the measurement laser beams 98 and 100 are irregularly reflected in the region where the processing marks 21b are formed. Therefore, the intensity distribution of the measurement laser beams 98 and 100 received by the height measuring units 44 and 46 becomes unstable.

Specifically, it is different from the intensity distribution (non-processed pattern) obtained when the measurement laser beams 98 and 100 are irradiated to a flat region of the surface 21a of the test member 21 where the processing marks 21b are not formed. The strength distribution (processing pattern) is detected. Therefore, when the machining pattern is detected by the height measuring units 44 and 46, there is no positional deviation between the irradiation regions 96a and the irradiation regions 98a and 100a in the Y-axis direction, or the positional deviation is within a predetermined range. Is confirmed.

On the other hand, when _{the values of the deviation amounts ΔY 1} and ΔY ₂ exceed a predetermined range, the irradiation regions 98a and 100a are irradiated to the regions of the surface 21a of the test member 21 where the processing marks 21b are not formed ( (See FIG. 4). Then, the non-processed pattern is detected by the height measuring units 44 and 46. As a result, it is confirmed that the positional deviation between the irradiation regions 96a and the irradiation regions 98a and 100a in the Y-axis direction exceeds a predetermined range.

When a non-processed pattern is detected, the chuck table 30 is moved along the Y-axis direction while irradiating the measurement laser beams 98 and 100 from the height measuring units 44 and 46. The movement of the chuck table 30 is performed while recording the amount of movement of the chuck table 30. Then, when the chuck table 30 is moved along the Y-axis direction, the measurement laser beams 98 and 100 are irradiated to the region of the test member 21 where the machining marks 21b are formed at a certain timing. At this time, the machining pattern is detected by the height measuring units 44 and 46.

Moving distance in the Y-axis direction of the chuck table 30 when the working pattern is detected by the height measuring unit 44 corresponds to the shift amount [Delta] Y _1. Further, the moving distance of the chuck table 30 in the Y-axis direction when the machining pattern is detected by the height measuring unit 46 corresponds to the _{deviation amount ΔY 2.} Then, the deviation amounts ΔY ₁ and ΔY ₂ are stored in the storage unit 64 (see FIG. 3) of the control unit 60, respectively. The accuracy of the measured deviation amounts ΔY ₁ and ΔY ₂ can be adjusted by controlling the spot diameter of the measurement laser beams 98 and 100 and the width of the processing mark 21b.

In the above, the _{test member 21 is used for measuring the deviation amounts ΔY 1} and ΔY ₂ , but the workpiece 11 may be used instead of the test member 21. The outer peripheral portion (surplus outer peripheral region) in which the device 15 of the workpiece 11 shown in FIG. 2 is not formed is later removed after the workpiece 11 is divided into a plurality of device chips. Therefore, the processing laser beam 96 may be irradiated to the outer peripheral surplus region to form a processing mark, and the deviation amounts ΔY ₁ and ΔY ₂ may be measured with reference to the processing mark.

Next, the irradiation area 96a is moved along the Y-axis direction by the irradiation position adjusting unit 82 (see FIG. 3) based on _{the deviation amounts ΔY 1} and ΔY ₂ stored in the storage unit 64, and is irradiated with the irradiation area 96a. The difference between the regions 98a and 100a in the Y-axis direction is reduced (irradiation position adjustment step). FIG. 5A is a plan view showing how the positional deviation between the irradiation region 96a of the processing laser beam 96 and the irradiation region 98a of the measurement laser beam 98 is corrected, and FIG. 5B is a processing laser. It is a top view which shows how the positional deviation between the irradiation area 96a of a beam 96 and the irradiation area 100a of a measurement laser beam 100 is corrected.

In the irradiation position adjusting step, first, one of the height measuring units 44 and 46 used in the step of forming the modified layer 11c on the workpiece 11 to be performed later (the modified layer forming step described later) is selected. To. Then, the position of the irradiation region 96a in the Y-axis direction is the irradiation region (one of the irradiation regions 98a and 100a) of the measurement laser beam irradiated from the selected height measurement unit (one of the height measurement units 44 and 46). ) Is adjusted.

For example, when the chuck table 30 is machined and fed in the direction indicated by the arrow A in FIG. 3 when the modified layer 11c is formed, the height measuring unit 44 is selected. Then, the processing unit 62 of the control unit 60 accesses the storage unit 64 and reads _{out the deviation amount ΔY 1 stored in the storage unit 64.} Further, the irradiation position control unit 68 controls the irradiation position adjusting unit 82 so that the irradiation region 96a moves to the irradiation region 98a side (upper side of FIG. 5A) in the Y-axis direction by a deviation amount ΔY of _{1 minute.} .. As a result, the positions of the irradiation region 96a and the irradiation region 98a in the Y-axis direction coincide with each other, and the irradiation region 96a and the irradiation region 98a are arranged on the same straight line along the X-axis direction.

On the other hand, when the chuck table 30 is machined and fed in the direction indicated by the arrow B in FIG. 3 when the modified layer 11c is formed, the height measuring unit 46 is selected. Then, the processing unit 62 of the control unit 60 accesses the storage unit 64 and reads _{out the deviation amount ΔY 2 stored in the storage unit 64.} Then, the irradiation position control unit 68 controls the irradiation position adjusting unit 82 so that the irradiation region 96a moves to the irradiation region 100a side (lower side in FIG. 5B) in the Y-axis direction by a deviation amount ΔY _{2 minutes.} To do. As a result, the positions of the irradiation region 96a and the irradiation region 100a in the Y-axis direction coincide with each other, and the irradiation region 96a and the irradiation region 100a are arranged on the same straight line along the X-axis direction.

In this way, the positional deviation between the irradiation regions 96a and the irradiation regions 98a and 100a is corrected. In the irradiation position adjustment step, it is not always necessary to completely match the positions of the irradiation areas 96a and the irradiation areas 98a and 100a in the Y-axis direction, and the difference in positions may be within a predetermined range. This predetermined range is appropriately set according to the width of the scheduled division line 13 (see FIG. 2) set on the workpiece 11.

Next, the laser beams 98 and 100 for measurement are irradiated to the workpiece 11 to measure the height of the workpiece 11, and the laser beam 96 for machining is irradiated to the workpiece 11 to the workpiece 11. The modified layer 11c is formed (modified layer forming step).

In the modified layer forming step, as described above, the chuck table 30 is moved along the X-axis direction while irradiating the processing laser beam 96 from the laser irradiation unit 42 toward the workpiece 11. As a result, the processing laser beam 96 is irradiated along the scheduled division line 13 (see FIG. 2) to form the modified layer 11c. Further, in the modified layer forming step, the work piece is processed while adjusting the height of the focusing point of the processing laser beam 96 based on the height of the work piece 11 measured by the height measuring units 44 and 46. The object 11 is irradiated with the processing laser beam 96.

For example, when the modified layer 11c is formed while moving the chuck table 30 in the direction indicated by the arrow A in FIG. 3, the measurement laser beam 98 is irradiated from the height measuring unit 44 along the scheduled division line 13. The height of the workpiece 11 is measured. Then, the processing laser beam 96 is subsequently irradiated to the region of the workpiece 11 irradiated with the measurement laser beam 98, and the modified layer 11c is formed along the planned division line 13.

On the other hand, when the modified layer 11c is formed while moving the chuck table 30 in the direction indicated by the arrow B in FIG. 3, the measurement laser beam 100 is irradiated from the height measuring unit 46 along the planned division line 13. The height of the workpiece 11 is measured. Then, the region of the workpiece 11 irradiated with the measurement laser beam 100 is subsequently irradiated with the processing laser beam 96, and the modified layer 11c is formed along the scheduled division line 13.

Further, when the workpiece 11 is irradiated with the processing laser beam 96, the position (height) of the focusing point of the processing laser beam 96 in the Z-axis direction is measured by the height measuring units 44 and 46. It is adjusted based on the height of the workpiece 11. Specifically, after the height of the region irradiated with the measurement laser beams 98 and 100 on the surface 11a of the workpiece 11 is measured by the height measuring units 44 and 46, the processing laser beam is applied to that region. When the 96 is irradiated, the height control unit 70 included in the processing unit 62 of the control unit 60 controls the drive unit 94 and adjusts the heights of the lens holder 90 and the condenser lens 92.

At this time, in the height control unit 70, the difference between the height of the condensing point of the processing laser beam 96 and the height of the surface 11a of the workpiece 11 measured by the height measuring units 44 and 46 is a predetermined value. That is, the drive unit 94 is controlled so that the focusing point of the processing laser beam 96 is positioned at a predetermined depth from the surface 11a of the workpiece 11. As a result, the height of the focusing point of the processing laser beam 96 is controlled based on the actually measured height of the surface 11a of the workpiece 11, and the modified layer 11c is moved from the surface 11a of the workpiece 11. It is formed to a predetermined depth.

The measurement laser beams 98 and 100 are continuously irradiated along the respective division scheduled lines 13. Then, the height of the workpiece 11 is also detected by the height measuring units 44 and 46 continuously along each scheduled division line 13. Therefore, the data of the continuous height position of the surface 11a of the workpiece 11 on each scheduled division line 13 is acquired by the height measuring units 44 and 46.

Further, the height of the focusing point of the processing laser beam 96 based on the measured height of the workpiece 11 is adjusted a plurality of times on each scheduled division line 13. That is, while the processing laser beam 96 is irradiated along one scheduled division line 13, the height of the focusing point of the processing laser beam 96 depends on the height of the surface 11a of the workpiece 11. Adjusted multiple times. As a result, the depth at which the modified layer 11c is formed can be kept constant even when the thickness of the workpiece 11 varies on one scheduled division line 13.

The frequency (interval) of adjusting the height of the condensing point of the processing laser beam 96 depends on the degree of variation in the thickness of the workpiece 11 and the moving speed (machining feed speed) of the chuck table 30. Can be set as appropriate. For example, the height of the focusing points of the processing laser beam 96 is adjusted so that the height of the focusing points is adjusted at predetermined intervals (for example, 0.5 mm intervals) on one scheduled division line 13. Frequency is set.

The timing for adjusting the height of the focusing point of the processing laser beam 96 is the distance between the area where the processing laser beam 96 is irradiated and the area where the measurement laser beams 98 and 100 are irradiated in the X-axis direction. , And, it is determined based on the moving speed (machining feed speed) of the chuck table 30. Specifically, when the measurement laser beams 98 and 100 are irradiated to a certain point of the workpiece 11 to measure the height, the timing at which the processing laser beam 96 is subsequently irradiated to the point is , The height of the focusing point of the processing laser beam 96 is adjusted based on the measurement result.

The formation of the modified layer 11c on the workpiece 11 is performed, for example, by reciprocally scanning the processing laser beam 96 with respect to the workpiece 11 in the machining feed direction. Specifically, first, while moving the chuck table 30 in the direction indicated by the arrow A, the processing laser beam 96 and the measuring laser beam 98 are irradiated along one scheduled division line 13 (first modified layer). Formation step).

Next, the moving unit 8 (see FIG. 1) moves the chuck table 30 in the Y-axis direction by the interval of the scheduled division line 13 (indexing feed). Then, while moving the chuck table 30 in the direction indicated by the arrow B in FIG. 3, the processing laser beam 96 and the measuring laser beam 100 are irradiated along the other scheduled division line 13 (second modified layer). Formation step).

When the processing laser beam 96 is reciprocally scanned, the irradiation position adjusting step is performed before the first modified layer forming step and before the second modified layer forming step, respectively. Specifically, after correcting the positional deviation between the irradiation region 96a of the processing laser beam 96 and the irradiation region 98a of the measurement laser beam 98 (see FIG. 5A), the first modified layer forming step. To carry out. Then, after correcting the positional deviation between the irradiation region 96a of the processing laser beam 96 and the irradiation region 100a of the measurement laser beam 100 (see FIG. 5B), the second modified layer forming step is carried out. ..

When the first modified layer forming step and the second modified layer forming step are alternately performed and the modified layer 11c is formed along all the planned division lines 13 included in the workpiece 11. The processing of the workpiece 11 by the laser processing device 2 is completed.

As described above, in the laser processing apparatus 2 according to the present embodiment, the laser irradiation unit 42 is provided with an irradiation position adjusting unit 82 that moves the region irradiated with the processing laser beam 96 along the Y-axis direction. .. Then, the irradiation position adjusting unit 82 adjusts the position of the region where the processing laser beam 96 is irradiated, so that the region where the processing laser beam 96 is irradiated and the measurement laser beams 98, 100 are irradiated. Reduce the difference in the Y-axis direction from the region.

As a result, the alignment between the region irradiated with the processing laser beam 96 and the region irradiated with the measuring laser beams 98 and 100 can be easily and highly accurately performed. Then, the workpiece 11 is processed in a state where the path irradiated with the processing laser beam 96 and the path irradiated with the measurement laser beams 98 and 100 match, and the processing is based on the thickness of the workpiece 11. The height of the focusing point of the laser beam 96 is adjusted with high accuracy.

The structure, method, and the like according to the above embodiment can be appropriately modified and implemented as long as they do not deviate from the scope of the object of the present invention.

11 Work piece 11a Front surface 11b Back surface 11c Modified layer (altered layer)
13 Scheduled line (street)
15 device 17 tape 19 frame 19a opening 21 test member (test wafer)
21a Surface 21b Machining marks 2 Laser machining equipment 4 Base 4a Surface (upper surface)
6 Support structure 8 Moving unit (moving mechanism)
10 Y-axis movement unit (Y-axis movement mechanism)
12 Y-axis guide rail 14 Y-axis moving table 16 Y-axis ball screw 18 Y-axis pulse motor 20 X-axis moving unit (X-axis moving mechanism)
22 X-axis guide rail 24 X-axis moving table 26 X-axis ball screw 28 X-axis pulse motor 30 Chuck table (holding table)
30a Holding surface 32 Clamp 40 Support arm 42 Laser irradiation unit 44,46 Height measuring unit (height measuring device)
48 Imaging unit (camera)
50 Display unit (display unit)
60 Control unit (control unit)
62 Processing unit 64 Storage unit 66 Oscillation control unit 68 Irradiation position control unit 70 Height control unit 72 Selection unit 80 Laser oscillator 82 Irradiation position adjustment unit 84 Mirror 86 Processing head 88 Housing 90 Lens holder 92 Condensing lens 94 Drive unit 96 Laser beam for processing 96a irradiation area (laser beam irradiation area for processing)
98 Laser beam for measurement 98a Irradiation area (Laser beam for measurement irradiation area)
100 Laser beam for measurement 100a Irradiation area (Laser beam irradiation area for measurement)

Claims (2)

A chuck table that holds the work piece on the holding surface,
A moving unit that moves the chuck table in a first direction parallel to the holding surface and a second direction parallel to the holding surface and perpendicular to the first direction.
A laser irradiation unit that irradiates the workpiece held by the chuck table with a processing laser beam for processing the workpiece.
A height at which the height of the workpiece is measured by irradiating the workpiece held by the chuck table with a laser beam for measurement and detecting the laser beam for measurement reflected by the workpiece. With a measuring unit,
The moving unit moves the chuck table along the first direction when the workpiece is machined by the working laser beam.
The laser irradiation unit includes an irradiation position adjusting unit that moves a region irradiated with the processing laser beam along the second direction.
The region irradiated with the measurement laser beam is positioned behind the region irradiated with the processing laser beam in the traveling direction of the chuck table when the workpiece is processed.
The irradiation position adjusting unit is irradiated with the processing laser beam so that the difference between the region irradiated with the processing laser beam and the region irradiated with the measurement laser beam in the second direction is reduced. A laser processing apparatus characterized in that the position of the region in the second direction can be adjusted. It is a processing method of a work piece that processes a work piece using a laser processing device.
The laser processing device
A chuck table that holds the work piece on the holding surface,
A moving unit that moves the chuck table in a first direction parallel to the holding surface and a second direction parallel to the holding surface and perpendicular to the first direction.
A laser irradiation unit that irradiates the workpiece held by the chuck table with a processing laser beam for processing the workpiece.
A height at which the height of the workpiece is measured by irradiating the workpiece held by the chuck table with a laser beam for measurement and detecting the laser beam for measurement reflected by the workpiece. With the measurement unit
A control unit having a storage unit for storing the amount of deviation between the region irradiated with the processing laser beam and the region irradiated with the measurement laser beam in the second direction is provided.
The laser irradiation unit includes an irradiation position adjusting unit that moves a region irradiated with the processing laser beam along the second direction.
A deviation amount storage step for storing the deviation amount in the storage unit,
After performing the deviation amount storage step, the region irradiated with the processing laser beam is moved along the second direction by the irradiation position adjusting unit based on the deviation amount stored in the storage unit. An irradiation position adjustment step that reduces the difference in the second direction between the region where the processing laser beam is irradiated and the region where the measurement laser beam is irradiated.
After performing the irradiation position adjusting step, while moving the chuck table along the first direction, the laser beam for measurement is irradiated on the work piece to measure the height of the work piece. It has a modified layer forming step of irradiating the workpiece with a laser beam for processing to form a modified layer on the workpiece.
In the modified layer forming step, the height of the focusing point of the processing laser beam irradiated to the region is adjusted based on the height of the region irradiated with the measurement laser beam of the work piece. A method for processing a work piece, which is characterized by performing.