JP5519426B2 - Laser processing equipment - Google Patents

Description

  The present invention relates to a laser processing apparatus for processing a workpiece (workpiece) such as a semiconductor wafer using a laser beam.

  In the manufacturing process of a semiconductor device, division lines are formed in a lattice pattern on the surface of a workpiece such as a semiconductor wafer, and devices such as IC and LSI are formed in each of a plurality of regions partitioned by the division lines. Thereafter, the work is divided for each device along the division line.

  As a method of dividing the workpiece, a laser beam is formed on the workpiece by scanning the holding table on which the workpiece is placed in the XY plane and irradiating the workpiece with a laser beam along the planned dividing line. A method of cleaving a workpiece along with a mechanical braking device has been proposed (for example, see Patent Document 1).

JP-A-10-305420

  By the way, when a curve is included in the planned machining line of the workpiece, it is necessary to perform curve machining that is two-dimensional scanning with a laser beam. In this case, there are two types of two-dimensional scanning: a method of scanning the holding table on which the work is placed in the XY plane, and a method of scanning the work in the X and Y directions of the optical system.

  In the system in which the holding table on which the workpiece is placed is scanned in the XY plane, it is necessary to adjust the acceleration / deceleration of the X-axis and Y-axis that are the drive axes to drive, and complicated control is required. While performing such control, it is difficult to drive a holding table having a weight exceeding 1 kg with a speed of several hundred mm / sec or more and an error accuracy of several μm.

  In the method of scanning the work in the X and Y directions, the optical axis is translated by changing the reflection position of the mirror, or the angle of the optical axis is changed by changing the mirror angle. Need to change. When the optical axis is moved in parallel by changing the reflection position of the mirror, the optical path length from the oscillator to the condenser changes depending on the scanning position, so that the condensing condition slightly changes depending on the processing position. When the angle of the optical axis is changed by changing the angle of the mirror, the optical path length from the condenser to the processing position changes depending on the scanning position, so that the condensing conditions slightly vary depending on the processing position.

  Therefore, if the processing is within the range where the difference in the condensing condition is acceptable, it is possible to scan and process an optical system with a small weight. However, when processing is performed over a wide range, it is difficult to increase the scanning speed of the optical system. In addition, the difference in light collecting conditions also becomes large.

  This invention is made | formed in view of this point, and it aims at providing the laser processing apparatus which can perform a curve process on a workpiece | work at high speed and with high precision.

  The laser processing apparatus of the present invention includes a holding table that holds a workpiece, a rotation support unit that rotatably supports the holding table with a vertical direction as a rotation axis, and a laser beam that irradiates the workpiece held on the holding table. Laser processing means for processing, wherein the rotation support part has an encoder for detecting a rotation angle, and the laser processing means includes an oscillator for oscillating a laser beam, and the oscillator A mirror that reflects the laser beam emitted from the mirror, a condenser that condenses the laser beam reflected by the mirror toward the workpiece, and the condensing point is scanned at least in one axial direction on the holding table. An operation unit for operating a mirror, and rotation angle information of the rotation support unit obtained from the encoder of the rotation support unit; And an operation control unit for controlling the operation unit based on the laser beam, and condensing the laser beam on the processing line of the workpiece by scanning the condensing point in the uniaxial direction while rotating the holding table. It is characterized by irradiating.

  According to this laser processing apparatus, the work focusing line is scanned in at least one axial direction with respect to the work processing scheduled line held on the rotating holding table, thereby being condensed along the work processing scheduled line. The laser beam is irradiated. In other words, the workpiece is curved by a combination of the rotational movement of the holding table and the one-dimensional scanning of the optical system. Therefore, it is not necessary to scan the holding table on which the workpiece is placed in the XY plane, or to scan the optical system in the X and Y directions. As a result, curve processing can be performed on the workpiece at high speed and with high accuracy.

  In the laser processing apparatus of the present invention, it is preferable to have a rotation support unit control means for controlling the rotation speed of the holding table so as to reduce the operation acceleration of the operation unit.

  ADVANTAGE OF THE INVENTION According to this invention, the laser processing apparatus which can perform curve processing on a workpiece | work with high speed and high precision can be provided.

It is the block diagram (a) which shows the whole apparatus of the laser processing apparatus which concerns on one embodiment of this invention, and the block diagram (b) which shows a laser beam processing means. It is a functional block diagram of the laser processing apparatus which concerns on the said embodiment. It is explanatory drawing of the laser processing performed using the laser processing apparatus which concerns on the said embodiment. It is explanatory drawing of the laser processing performed using the laser processing apparatus which concerns on the said embodiment. It is explanatory drawing of the laser processing performed using the laser processing apparatus which concerns on the said embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
(About the configuration of laser processing equipment)
FIG. 1 is a block diagram showing (a) the entire apparatus and (b) a laser beam processing means of a laser processing apparatus 1 according to an embodiment of the present invention.

  A laser processing apparatus 1 shown in FIG. 1A is provided with a pair of Y-axis guide rails 11 a and 11 b formed on the processing table 10 in the Y-axis direction. A Y-axis table 12 is installed so as to be movable in the Y-axis direction along the Y-axis guide rails 11a and 11b. A nut portion (not shown) is formed on the back side of the Y-axis table 12, and a ball screw 13 is attached to the nut portion. A drive motor 14 is connected to the end of the ball screw 13, and the ball screw 13 is rotationally driven by the drive motor 14.

  On the Y-axis table 12, a pair of X-axis guide rails 15a and 15b formed in the X-axis direction are provided. An X-axis table 16 is installed so as to be movable in the X-axis direction along the X-axis guide rails 15a and 15b. A nut portion (not shown) is formed on the back side of the X-axis table 16, and a ball screw 17 is attached to the nut portion. A drive motor 18 is connected to the end of the ball screw 17, and the ball screw 17 is rotationally driven by the drive motor 18.

  A holding table 20 is installed on the X-axis table 16 via a rotation support portion 21. The workpiece W processed along the scheduled processing line 30 is held by the holding table 20 while being supported by the annular frame 32 via the adhesive tape 31.

  The holding table 20 includes a work holding unit 22 that sucks and holds a work W provided on an upper portion of the rotation support unit 21, and a frame holding unit 23 that holds an annular frame 32.

  The rotation support unit 21 supports the holding table 20 so as to be rotatable about the vertical direction (Z-axis direction) as a rotation axis. The rotation support unit 21 rotates the holding table 20 under the control of a rotation support unit control unit 212 described later.

As the workpiece W, for example, a semiconductor wafer such as silicon (Si), gallium strain (GaAs), or silicon carbide (SiC), an adhesive member such as DAF provided on the back surface of the wafer for chip mounting, or a semiconductor product Examples include packages, ceramics, glass, sapphire (Al ₂ O ₃ ) -based inorganic material substrates, various electronic components such as LCD drivers, and various processing materials that require micron-order processing position accuracy.

  A support column 24 is erected at the rear of the processing table 10. An arm 25 extending above the holding table 20 is provided at the upper end of the support column 24. A laser irradiation unit 26 that irradiates the workpiece W held on the holding table 20 with a laser beam is supported at the tip of the arm 25. The laser irradiation unit 26 houses laser processing means 27 that is an optical system.

  The laser processing means 27 shown in FIG. 1B drives an oscillator 271 that oscillates a laser beam, a plurality of mirrors 272 to 274 that reflect the laser beam oscillated from the oscillator 271, and a mirror 274 that can swing back and forth. The operation unit 275 and a condenser 276 that condenses the laser beam reflected by the mirror 274 onto the work W on the holding table 20 are configured. The mirror 274 is attached to one end of the operating unit 275, and the mirrors 272 and 273 are arranged at positions where the laser beam oscillated from the oscillator 271 is reflected by the mirror 274. The operation unit 275 is configured by, for example, a galvano scanner, and changes the reflection angle by driving the mirror 274 under the control of the operation control unit 277 described later. In the laser processing means 27, the converging point of the laser beam from the oscillator 271 can be scanned on the workpiece W of the holding table 20 by controlling the reflection angle of the mirror 274 with the operating unit 275. ing.

  FIG. 2 is a functional block diagram of the laser processing apparatus 1. As shown in FIG. 2, the rotation support unit control means 212 is connected to the rotation support unit 21 and controls the rotation speed of the rotation support unit 21. Specifically, the rotation support unit control unit 212 reduces or increases the rotation speed of the rotation support unit 21 while referring to a rotation angle and a rotation speed fed back from an encoder 211 described later. The rotation speed of the holding table 20 is determined by the control of the rotation support unit control unit 212.

  The rotation support unit 21 includes an encoder 211. The encoder 211 is composed of, for example, a rotary encoder, and detects the rotation angle and rotation speed of the rotation support unit 21. Then, the encoder 211 outputs the detected rotation angle information of the rotation support unit 21 to the operation control unit 277. The encoder 211 feeds back the detected rotation angle and rotation speed of the rotation support unit 21 to the rotation support unit control means 212.

  The operation control unit 277 is connected to the operation unit 275 and controls the operation of the operation unit 275. Specifically, the operation control unit 277 places the condensing point of the laser beam reflected from the mirror 274 at a desired position on the workpiece W based on the rotation angle information of the rotation support unit 21 acquired from the encoder 211. The operation unit 275 is controlled as described above. By such control of the operation control unit, the mirror 274 is driven and the condensing point on the workpiece W is scanned.

  When the rotation angle of the rotation support unit 21 acquired from the encoder 211 is not 0 °, that is, when the holding table 20 is rotating, the operation control unit 277 causes the operation unit 275 to drive the mirror 274 one-dimensionally. Control as follows. Here, the one-dimensional driving of the mirror 274 means that the mirror 274 is driven only in any direction indicated by the arrow a or the arrow b in FIG.

  When the rotation angle of the rotation support unit 21 acquired from the encoder 211 is 0 °, that is, when the holding table 20 is not rotating, the operation control unit 277 causes the operation unit 275 to move the mirror 274 two-dimensionally. Control to drive. Here, the two-dimensional driving of the mirror 274 means driving the mirror 274 in the directions indicated by the arrows a and b in FIG.

  The larger the rotation angle per unit time of the rotation support unit 21 acquired from the encoder 211, the faster the rotation speed of the holding table 20, and the higher the driving speed of the mirror 274 by the operation unit 275. On the other hand, the smaller the rotation angle per unit time of the rotation support unit 21 acquired from the encoder 211, the lower the rotation speed of the holding table 20, and the lower the drive of the mirror 274 by the operation unit 275.

(About laser processing using the laser processing device 1)
Hereinafter, laser processing performed using the laser processing apparatus 1 will be described with reference to FIGS. In the following, as shown in FIG. 3, the workpiece W to be laser processed is a rectangle, and the workpiece W has a triangular processing planned line 30 with rounded corners, and a circle disposed near each inner corner of the triangle. The case where the shape processing line 30 is designated will be described. Hereinafter, for convenience of explanation, the triangular processing scheduled line 30 is referred to as an outer peripheral portion 301 of the processing scheduled line 30, and the circular processing scheduled line 30 is referred to as a detailed portion 302 of the processing scheduled line 30.

  First, a case where laser processing is performed on the outer peripheral portion 301 of the processing scheduled line 30 of the workpiece W will be described. 3 and 4 are plan views when the outer peripheral portion 301 of the processing planned line 30 of the workpiece W is laser processed. When processing the outer peripheral portion 301 of the scheduled processing line 30, the laser processing is performed on the workpiece W while rotating the holding table 20 in the laser processing apparatus 1 according to the present embodiment.

  First, as shown in FIG. 3A, the workpiece W is carried onto the holding table 20 in the laser processing apparatus 1 configured as described above. Then, the workpiece | work W is adsorb | sucked by the workpiece | work holding | maintenance part 22 with the suction source which is not illustrated. Then, the position of the holding table 20 is adjusted by the X-axis table 16 and the Y-axis table 12 so that the condensing point 40 is positioned in the vicinity of the outer peripheral portion 301 of the processing line 30 of the workpiece W.

  Subsequently, the condensing point 40 is scanned in one axial direction while rotating the holding table 20, and laser processing is performed along the outer peripheral portion 301 of the processing scheduled line 30 of the workpiece W. At this time, in the laser processing apparatus 1, the rotation support unit control unit 212 controls the rotation speed of the rotation support unit 21, and the holding table 20 is rotated via the rotation support unit 21. Then, the operation unit 275 is controlled by the operation control unit 277 based on the rotation angle information of the rotation support unit 21 acquired from the encoder 211. Then, the mirror 274 attached to the operation unit 275 is one-dimensionally driven, and accordingly, the condensing point 40 is one-dimensionally scanned on the workpiece W.

  When the holding table 20 is rotated, the processing scheduled line 30 rotates along a locus as shown by a chain line in FIG. From this, it can be seen that every point on the outer peripheral portion 301 of the processing scheduled line 30 always passes the position indicated by the arrow R. Therefore, the entire outer peripheral portion 301 of the planned processing line 30 can be laser-processed by one-dimensionally scanning the condensing point 40 in at least one axial direction within the necessary scanning width d of the laser beam equal to the width of the arrow R. It becomes. As described above, according to the laser processing apparatus 1 according to the present embodiment, the condensing point 40 is scanned in one axial direction while rotating the holding table 20, and along the outer peripheral portion 301 of the processing line 30 of the workpiece W. Therefore, the necessary scanning width d of the laser beam can be reduced.

  Note that the one-dimensional scanning of the condensing point 40 at least in one axial direction means that the mirror 274 is scanned by the operating unit 275 so that the condensing point 40 is scanned only in either the x-axis direction or the y-axis direction in FIG. To drive. For example, the condensing point 40 is scanned so as to reciprocate on the arrow R.

  Examples of the laser processing performed along the planned work line 30 of the workpiece W include, for example, processing that fully cuts the work W by ablation along the planned work line 30 of the work W, and work along the planned work line 30 of the work W. Examples include a process for forming a groove on W and a process for forming a modified layer in which the irradiated portion is made brittle by focusing a laser beam on the inside of the work W along the planned machining line 30 of the work W. Here, the modified layer refers to a region where the density, refractive index, mechanical strength and other physical characteristics of the workpiece W are different from the surroundings. For example, (1) a melt treatment region, (2) a crack region, a dielectric breakdown region, (3) a refractive index change region, and the like may be a region where these are mixed.

  By the way, depending on the shape of the planned machining line 30, the swing width of the condensing point 40 of the planned machining line 30 may vary greatly depending on the rotational position. FIG. 4A shows the positions of the condensing points 40a and 40b when the processing line 30a (shown by a chain line) is rotated by 20 ° and moved to the position of the processing line 30b (shown by a one-dot chain line). Show. At this time, the swing width of the condensing point 40 is equal to the distance between the condensing points 40a-40b indicated by the solid line A.

  On the other hand, FIG. 4B shows the condensing points 40c and 40d when the planned processing line 30c (shown by a chain line) is rotated by 20 ° and moved to the position of the planned processing line 30d (shown by a one-dot chain line). Indicates the position. At this time, the swing width of the condensing point 40 is equal to the distance between the condensing points 40c-40d indicated by the solid line B.

  4 (a) and 4 (b), it can be seen that even when the same angle is rotated, the swing width of the condensing point 40 of the processing scheduled line 30 varies greatly depending on the rotation position. Since the distance between the condensing points 40c-40d (solid line B in FIG. 4B) is larger than the distance between the condensing points 40a-40b (solid line A in FIG. 4A), the condensing point 40 is scanned. Therefore, the operating range per unit time of the mirror 274 by the operating unit 275 is also increased. Therefore, in the state shown in FIG. 4B, it can be said that the operation acceleration of the operation unit 275 is larger than that in the state shown in FIG. That is, in the state shown in FIG. 4B, it can be said that the load applied to the laser processing means 27 including the operating unit 275 and the mirror 274 is increased compared to the state shown in FIG.

  Here, in order to reduce the operation acceleration of the operation unit 275, the rotation support unit control unit 212 may perform control to reduce the rotation speed of the holding table 20. By reducing the operation acceleration of the operation unit 275, the load applied to the laser processing means 27 can be reduced even if the focal point 40 has a large swing width. After that, when the amplitude of the condensing point 40 decreases, the rotation support unit control means 212 may control to increase the rotation speed of the holding table 20 in order to increase the laser processing speed.

  Next, a case where laser processing is performed on the detailed portion 302 of the work scheduled processing line 30 will be described. FIG. 5 is a plan view of the case where the detailed portion 302 of the work planned processing line 30 of the workpiece W is laser processed. Here, the detailed portion 302 refers to the planned processing line 30 having a size that allows laser processing to be performed within a range in which a difference in condensing conditions is acceptable. When processing the detailed portion 302 of the scheduled processing line 30, in the laser processing apparatus 1 according to the present embodiment, laser processing is performed on the workpiece W while the holding table 20 is stopped.

  First, as shown in FIG. 5, the position of the holding table 20 is adjusted by the X-axis table 16 and the Y-axis table 12 so that the condensing point 40 is positioned in the vicinity of the detailed portion 302 of the processing line 30 of the workpiece W. To do. Thereafter, the condensing point 40 is two-dimensionally scanned, and the workpiece W is laser processed along the detailed portion 302 of the processing scheduled line 30. At this time, in the laser processing apparatus 1, the rotation support unit control unit 212 is not controlled to rotate the rotation support unit 21. Therefore, the holding table 20 does not rotate, and the operation control unit 277 controls the operation unit 275 based on information that the rotation angle of the rotation support unit 21 acquired from the encoder 211 is 0 °. In other words, the operation control unit 277 controls the operation unit 275 so that the mirror 274 is two-dimensionally driven, and accordingly, the condensing point 40 is two-dimensionally scanned on the workpiece W. In this way, by performing two-dimensional scanning of the condensing point 40, it is possible to laser process the entire detailed portion 302 of the processing scheduled line 30.

  Note that the two-dimensional scanning of the condensing point 40 means that the mirror 274 is driven by the operating unit 275 so as to scan the condensing point 40 in the x-axis and y-axis directions in FIG.

  As described above, according to the laser processing apparatus 1 according to the present embodiment, the workpiece W held on the rotating holding table 20 is collected in at least one axial direction with respect to the planned processing line 30 (outer peripheral portion 301). By scanning the light spot 40, the laser beam condensed along the processing planned line 30 of the workpiece W is irradiated and laser processing is performed. Therefore, even when curve processing is performed with a laser beam, it is not necessary to scan the holding table 20 on which the workpiece W is placed in the XY plane, or to scan the condensing point 40 in the X and Y directions. As a result, since the laser beam machining can be performed on the workpiece W while maintaining the condensing condition, the curve machining can be performed on the workpiece at high speed and with high accuracy.

  In addition, the laser processing apparatus 1 according to the present embodiment includes the rotation support unit control unit 212 that controls the rotation speed of the holding table 20 so as to reduce the operation acceleration of the operation unit 275 in the laser processing unit 27. . Therefore, laser processing can be performed without increasing the load on the laser processing means 27 even when the focal width of the condensing point 40 is large. As a result, it is possible to suppress the deterioration over time associated with the use of the laser processing means 27 and to ensure the processing accuracy over a long period of time.

  Furthermore, according to the laser processing apparatus 1 according to the present embodiment, the laser processing unit 27 includes the X-axis table 16 and the Y-axis table 12 which are moving units that translate the holding table 20 in a horizontal plane. The operation unit 275 is configured to drive the mirror 274 in the x-axis and y-axis directions and scan the condensing point 40 not only in the uniaxial direction but also in a direction intersecting the uniaxial direction. Therefore, the condensing point 40 can be two-dimensionally scanned, and the workpiece W can be laser processed along the detailed portion 302 of the processing scheduled line 30. Accordingly, it is possible to perform laser processing on the workpiece W at high speed and with high accuracy by moving only the optical system side with less weight without rotating the heavy holding table 20.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, in the above-described embodiment, a case has been described in which the workpiece W is a rectangle, and the planned processing line 30 includes a triangular outer peripheral portion 301 with rounded corners and a circular detail portion 302. However, the shapes of the workpiece W and the planned processing line 30 are not limited to the above-described configuration, and arbitrary shapes can be applied.

  As described above, the present invention has an effect that it is possible to perform curve processing by laser on a workpiece at high speed and with high accuracy, and is particularly useful when a curve is included in a planned processing line in the workpiece.

DESCRIPTION OF SYMBOLS 1 Laser processing apparatus 12 Y-axis table 16 X-axis table 20 Holding table 21 Rotation support part 211 Encoder 212 Rotation support part control means 22 Work holding part 26 Laser irradiation unit 27 Laser processing means 271 Oscillators 272, 273, 274 Mirror 275 Operation part 276 Condenser 277 Operation control unit 30 Planned processing line 301 Outer peripheral portion 302 Detailed portion 40 Condensing point W Workpiece

Claims (2)

A holding table that holds the workpiece; a rotation support portion that rotatably supports the holding table with a vertical direction as a rotation axis; and laser processing means that irradiates the workpiece held on the holding table with a laser beam to process the workpiece. A laser processing apparatus comprising:
The rotation support unit includes an encoder that detects a rotation angle;
The laser processing means includes an oscillator that oscillates a laser beam, a mirror that reflects the laser beam oscillated from the oscillator, a condenser that condenses the laser beam reflected by the mirror toward the workpiece, and the holding An operation unit that operates the mirror so as to scan a condensing point on at least one axis on the table, and the operation unit based on rotation angle information of the rotation support unit acquired from the encoder of the rotation support unit. An operation control unit for controlling,
A laser processing apparatus, wherein the laser beam is focused and irradiated on a processing line of the workpiece by scanning a condensing point in the uniaxial direction while rotating the holding table. The laser processing apparatus according to claim 1, further comprising a rotation support unit control unit configured to control a rotation speed of the holding table so as to reduce an operation acceleration of the operation unit.

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