JP6151130B2 - Laser processing equipment - Google Patents

Description

  The present invention relates to a laser processing apparatus capable of forming a processing groove by irradiating a workpiece with a laser beam.

  In recent years, as a method of dividing a plate-like workpiece such as a semiconductor wafer, a laser processing groove is formed by irradiating a pulsed laser beam along a planned division line formed on the workpiece. Has been proposed (see Patent Document 1, for example).

  Since the surface of the wafer contains various materials such as various functional films, insulating films, and TEG (Test Element Group), the above processing method is suitable for processing with a predetermined depth from the surface of the wafer. In order to form the groove, it is required to control the output (laser power) of the laser beam with high accuracy. The laser power is set based on the value measured with a power meter.

JP 2006-120797 A

  However, since the power meter itself has a tolerance of several percent due to individual differences, even if the laser power of multiple laser processing devices is adjusted using the same power meter, There is a problem that the depth varies.

  The present invention has been considered in view of the above problems, and its purpose is to set processing conditions of a plurality of laser processing apparatuses and form a processing groove having a desired depth without being affected by the tolerance of a power meter. The purpose is to do.

  The present invention relates to a chuck table that holds a workpiece, a laser beam oscillator that oscillates a laser beam, and an output adjusting unit that adjusts the output of the laser beam oscillated from the laser beam oscillator by adjusting the angle of the half-wave plate. Further, the present invention relates to a laser processing apparatus comprising a laser beam irradiating means having a condenser for condensing a laser beam on a workpiece held on a chuck table, and a control means for controlling at least the output adjusting means. / Several measured values that measure the depth from the surface of the processed groove formed by irradiating the laser beam whose output is adjusted by sequentially changing the angle of the two-wavelength plate from the surface side of the workpiece, and the actual measurement Storage means for storing correlation data with a plurality of sequentially changed angles of the half-wave plate corresponding to the value, and from the surface of the workpiece Input means for inputting desired machining groove depth information, and when the desired machining groove depth information is input by the input means, the control means outputs the correlation data of the actual measurement values stored in the storage means. Based on this, the angle of the half-wave plate of the output adjusting means is adjusted to an angle corresponding to the desired processing groove depth.

  In the present invention, correlation data between the angle of the half-wave plate for adjusting the laser output and the actual processing groove depth is stored in the storage means for each laser processing apparatus, and the desired processing groove depth is input by the input means. Is input, the control means adjusts the half-wave plate to an angle corresponding to the desired processing groove depth, so that variations in the processing groove depth can be prevented from device to device. Further, since it is only necessary to input a desired machining groove depth without using a power meter, it is easy to set machining conditions.

The perspective view which shows a laser processing apparatus. The block diagram which shows the structure of a laser beam irradiation means. The graph which shows correlation data. Sectional drawing which shows the processing groove | channel formed in the to-be-processed object.

  A laser processing apparatus 1 shown in FIG. 1 is an apparatus in which laser processing means 40 performs laser processing on a workpiece held on a chuck table 10.

  The chuck table 10 can be rotated while holding a workpiece, and can be moved in the ± X directions by being driven by the X-axis direction feeding means 20.

  The X-axis direction feeding means 20 includes a ball screw 21 extending in the X-axis direction, a motor 22 connected to one end of the ball screw 21, a pair of guide rails 23 extending parallel to the ball screw 21, and an internal nut (not shown). And a moving base 24 whose lower part is in sliding contact with the guide rail 23 and is driven by the motor 22 to rotate the ball screw 21 so that the moving base 24 is guided by the guide rail 23. The chuck table 10 can be moved in the same direction by moving in the ± X direction.

  The chuck table 10 and the X-axis direction feeding means 20 are driven by the Y-axis direction feeding means 30 and are movable in the ± Y directions. The Y-axis direction feeding means 30 includes a ball screw 31 extending in the Y-axis direction, a motor 32 connected to one end of the ball screw 31, a pair of guide rails 33 arranged in parallel to the ball screw 31, and an internal nut (not shown). And a moving base 34 whose lower part is slidably in contact with the guide rail 33. The moving base 34 is moved to the guide rail 33 by the rotation of the ball screw 31 driven by the motor 32. Guided and moved in the ± Y direction, the chuck table 10 disposed on the moving base 34 via the X-axis direction feeding means 20 can be moved in the same direction.

  As shown in FIG. 2, the laser processing unit 40 includes a laser beam oscillator 70 that oscillates a laser beam, an output adjustment unit 60 that adjusts the output of the laser beam oscillated from the laser beam oscillator 70, and a workpiece that is held on the chuck table 10. A laser beam irradiating means 50 including a condenser 53 for condensing a laser beam on an object and a control means 80 for controlling at least the output adjusting means 60 are provided.

  The laser beam oscillator 70 is an oscillator that oscillates a laser beam having a predetermined wavelength. For example, the laser beam oscillator 70 includes a laser beam oscillator including a YAG laser oscillator and a YVO4 laser oscillator, an oscillator that oscillates a laser beam in the infrared wavelength region, and the like.

  The output adjusting means 60 includes a half-wave plate 61 disposed on the optical path of the laser beam emitted from the laser beam oscillator 70, a motor 62 that rotates the half-wave plate by a predetermined angle, and a half-wave plate 61. A polarization beam splitter 63 positioned on the optical path of the laser beam that has passed through the laser beam, and an absorber 64 that absorbs the laser beam branched by the polarization beam splitter 63.

  The half-wave plate 61 changes the linear polarization direction of the laser beam LB oscillated by the laser beam oscillator 70 according to the rotation angle. The polarization beam splitter 63 transmits a laser beam having a predetermined linear polarization direction out of the laser beam that has passed through the half-wave plate 61 toward the laser beam irradiation unit 50 and has a linear polarization direction other than the predetermined linear polarization direction. The laser beam is branched to the absorber 64 side. The absorber 64 is for absorbing the laser beam branched by the polarization beam splitter 63, and may be composed of, for example, a matte black metal in order to absorb the laser beam satisfactorily.

  The laser beam application means 50 collects the polarization direction setting unit 51 positioned on the optical path of the laser beam that has passed through the beam splitter 63, the mirror element 52 that reflects the laser beam and changes its direction, and the laser beam guided by the mirror element 52. And a concentrator 53 that emits light. The polarization direction setting unit 51 is a generally known homogenizer using a diffractive optical element or the like. The polarization direction setting unit 51 converts a laser beam whose cross-sectional energy distribution is Gaussian in a direction orthogonal to the processing progress direction into cross-sectional energy in the direction orthogonal to the processing progress direction. Conversion into a laser beam whose distribution is constant within the processing range. The mirror element 52 is for reflecting the laser beam that has passed through the half-wave plate 61 toward the condenser lens 53 side. The condensing lens 53 is disposed so as to face the workpiece W, and focuses the laser beam reflected by the mirror element 52 by positioning a condensing point inside the workpiece W.

  The control unit 80 includes at least a CPU and a storage element such as a memory, and controls the motor 62 to adjust the angle of the half-wave plate 61 and pass the laser beam LB toward the laser beam irradiation unit 50. Adjust the output of. The control means 80 is connected to an input means 81 such as a keyboard and a storage means 82 having a storage element such as a memory. The control means 80 accepts an input from the input means 81 and is connected to the storage means 82. Data can be input and output between them.

  For example, as shown in FIG. 3, the storage unit 82 stores a correlation between the rotation angle of the half-wave plate 61 and the processing groove depth D. This correlation is obtained by adjusting the output by sequentially changing the angle of the half-wave plate 61 from a predetermined reference position and irradiating a laser beam from the surface side of the workpiece, and the workpiece in the formed groove The depth from the surface of the half-wave plate is measured, and the rotation angle of the half-wavelength plate 61 is associated with the measured value.

  The measured value of the machining groove depth is obtained by dividing the workpiece by applying an external force after forming the machining groove and measuring the depth of each machining groove with a microscope or the like. Such a correlation is stored for each laser processing apparatus 1 when there are a plurality of laser processing apparatuses 1. Further, in each laser processing apparatus 1, correlation data is obtained for each feed rate in the ± X direction of the chuck table 10 shown in FIG. 1 and stored in the storage means 82. The feed rate in the ± X direction of the chuck table 10 does not affect the inclination of the graph, but the intercept value varies depending on the feed rate. In the example of FIG. 3, the case where the feed speed is 100 mm / s and the case where it is 120 mm / s are stored, but the present invention is not limited to this.

  Further, when there are a plurality of types of workpiece materials, correlation data is obtained for each workpiece material and stored in the storage means 82. The slope of the graph of FIG. 3 changes depending on the material.

  Next, an operation example of the laser processing apparatus 1 will be described. The workpiece W is held on the chuck table 10. A division line (not shown) in which a machining groove is to be formed is formed in the workpiece, and desired machining groove depth information of the machining groove to be formed is input from the input unit 81 and stored by the operator. It is stored in the means 82.

  First, the X-axis direction feeding unit 20 moves the chuck table 10 holding the workpiece W in the −X direction and moves it below the laser beam irradiation unit 50. Then, while moving the chuck table 10 in the ± X direction, the laser beam irradiation means 50 irradiates a laser beam along a planned division line formed on the workpiece W to ablate the surface of the workpiece W. For example, when the workpiece W is a silicon workpiece, a laser beam that absorbs silicon is irradiated. Then, as shown in FIG. 4, a processing groove 9 having a depth D from the surface of the workpiece is formed.

  At the time of laser beam irradiation, the control unit 80 reads the correlation data shown in FIG. 3 stored in the storage unit 81 and obtains the angle of the half-wave plate 61 corresponding to the desired processing depth information. Then, the control unit 80 rotates the half-wave plate 61 by the determined angle. For example, when the feed speed of the chuck table 10 is 120 mm / s and the desired processing groove depth D is 25 [μm], the rotation angle of the corresponding half-wave plate 61 is 1.2 degrees. Therefore, the control means 80 controls the motor 62 to rotate the half-wave plate 61 by 1.2 degrees.

  Thus, the correlation data between the angle of the half-wave plate 61 for adjusting the laser output and the actual processing groove depth is stored for each laser processing apparatus, and the desired processing groove is input by the input unit 81. When the depth is input, the control means 80 adjusts the half-wave plate 61 to an angle corresponding to the desired processing groove depth, so there is no need to use a power meter, and the desired processing groove depth. It is possible to prevent variations in the machining groove depth for each apparatus simply by inputting.

  After the processing groove having a desired depth is formed in this manner, the workpiece W can be divided into individual chips by applying an external force to the workpiece W.

1: Laser processing apparatus 10: Chuck table 20: X-axis direction feeding means 21: Ball screw 22: Motor 23: Guide rail 24: Moving base 30: Y-axis direction feeding means 31: Ball screw 32: Motor 33: Guide rail 34: Moving base 40: Laser processing means 50: Laser beam irradiation means 51: Polarization direction setting unit 52: Mirror element 53: Condenser 60: Output adjustment means 61: Half-wave plate 62: Motor 63: Polarizing beam splitter 64: Absorber 70: Laser beam oscillator 80: Control means 81: Input means 82: Storage means W: Work piece 9: Processing groove

Claims (1)

A chuck table for holding a workpiece, a laser beam oscillator for oscillating a laser beam, an output adjusting means for adjusting an output of the laser beam oscillated from the laser beam oscillator by adjusting an angle of a half-wave plate, In a laser processing apparatus comprising: a laser beam irradiating unit including a condenser for condensing the laser beam on a workpiece held on a chuck table; and a control unit that controls at least the output adjusting unit.
Measure the depth from the surface of the groove formed by irradiating the surface of the workpiece with a laser beam whose output is adjusted by sequentially changing the angle of the half-wave plate of the output adjusting means. Storage means for storing correlation data between a plurality of actually measured values and a plurality of sequentially changed angles of the half-wave plate corresponding to the actually measured values;
Input means for inputting desired machining groove depth information from the surface of the workpiece,
When the desired processing groove depth information is input by the input means, the control means, based on the correlation data of the measured values stored in the storage means, the ½ wavelength of the output adjustment means. A laser processing apparatus, wherein the angle of the plate is adjusted to an angle corresponding to a desired processing groove depth.

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