JP6196884B2 - Laser processing equipment - Google Patents

Description

  The present invention relates to a laser processing apparatus that performs laser processing on a plate-shaped workpiece, and more particularly, to a laser processing apparatus that performs processing by irradiating a laser beam along a predetermined division line in a plate-shaped workpiece such as a semiconductor wafer.

  A wafer, which is a plate-like workpiece having a plurality of devices formed on the surface, is divided into individual device chips by being divided along a predetermined division line dividing the surface. As an apparatus for dividing such a wafer, for example, cutting apparatuses disclosed in Patent Documents 1 and 2 are known.

  The cutting apparatus of Patent Document 1 includes a chuck table that holds a wafer, and a rotating blade that cuts the wafer along a planned division line. Moreover, the cutting apparatus is provided with the process feed means and index feed means each installed on a base.

  In the chuck table, the wafer is held in a state where the division lines formed in a lattice shape are parallel to the X direction and the Y direction. The machining feed means feeds the chuck table in the X direction, and contacts the wafer with a rotating blade that rotates during the machining feed, so that a machining line is formed along the division line extending in the X direction. The indexing and feeding means is provided so that the rotating blade can be indexed and fed in the Y direction, and indexes and feeds the rotating blade by the interval of the division lines each time a processing line is formed. As a result, processing lines are sequentially formed on a plurality of division lines arranged in the Y direction on the wafer.

  Here, in forming the machining line, it is required to increase the accuracy of the machining position so as to coincide with the position of the planned division line. In view of this, in the cutting apparatus disclosed in Patent Document 2, an imaging unit including a CCD camera is provided at a position aligned with the rotating blade in the X direction. The imaging unit images the processing line and the planned division line formed by the rotating blade, and measures a difference (separation distance) in the Y direction between the processing line and the planned division line from the imaging result. Then, by moving the rotating blade in the Y direction by the movement amount and the index feeding means according to the measured difference, the machining line is corrected to coincide with the planned division line.

JP 2001-308034 A Japanese Patent No. 2501970

  However, in the cutting apparatuses disclosed in Patent Documents 1 and 2, the feed screw and the slider constituting the index feed means are distorted and the index feed direction is inclined or bent, and the index feed direction with respect to the machining feed direction of the rotary blade. May not be orthogonal. For this reason, even if it correct | amends so that a division | segmentation planned line and a processing line may correspond, there exists a problem that a processing line will detach | leave from a division | segmentation planned line by the cutting after this correction | amendment, and the processing precision to a wafer will fall.

  The present invention has been made in view of such a point, and an object of the present invention is to provide a laser processing apparatus capable of suppressing a decrease in processing accuracy even when an angle in an indexing feeding direction by an indexing feeding means is changed. And

  A laser processing apparatus according to the present invention includes a chuck table that holds a plate-like workpiece having a scheduled division line, and a laser oscillator that irradiates a laser beam along the scheduled division line of the plate-like workpiece held by the chuck table. A laser processing means, an imaging camera that is disposed in the processing feed direction away from the laser oscillator, and that captures a processing line obtained by laser processing a line to be divided of a plate-like work held by the chuck table with a laser oscillator, and a chuck table A machining apparatus comprising: a machining feed means for machining and feeding in the X direction as a machining feed direction; and an index feed means for supporting the machining feed means from below and indexing and feeding in the Y direction as an index feed direction. The movement direction of the chuck table and the machining feed means is opposite to the Y direction by index feed by the index feed means. When the angle changes, the imaging camera captures images for each of the plurality of index stop positions by the index feed means within the range of movement of the index feed means. A recognition unit for recognizing a difference in a Y direction between a processing point obtained by laser processing of a workpiece and a planned division line, and a difference in a Y direction recognized by the recognition unit for each of a plurality of index stop positions is stored as a correction value. A storage unit; and a control unit that controls driving of the indexing feeding unit so as to correct the position of the machining line at each indexing stop position based on the correction value stored in the storage unit. .

  According to this configuration, the correction values for each of the plurality of index stop positions are obtained, and control is performed to correct the position of the machining line at each index stop position. The processing line can be made to match. Thereby, the processing accuracy of the plate-like workpiece can be maintained satisfactorily, and as a result, the quality and the like of the processed product can be improved. Moreover, since the indexing feeding means supports the machining feeding means from below, the relative angle between the indexing feeding and the machining feeding can be easily maintained as compared with the case where each is installed at a different position. The processing accuracy can be improved.

  Further, in the laser processing apparatus of the present invention, when the storage unit does not store a correction value for the predetermined index stop position by the index feeding means, the predetermined index stop is selected from the plurality of correction values stored in the storage unit. It is preferable to provide a calculation unit that calculates a correction value at a predetermined index stop position using two correction values closest to the position and a linear interpolation method. In this configuration, even if the number and position of the index feed stop positions to be laser processed are different from the index feed stop position for which the correction value is obtained, the correction value is obtained for each index feed stop position and the machining line The formation position can be corrected.

  According to the present invention, since control for correcting the locus of the machining line is performed at each index stop position, even if the angle in the index feed direction by the index feed means changes, it is possible to suppress a decrease in machining accuracy. it can.

It is a schematic perspective view of the laser processing apparatus which concerns on this Embodiment. It is a top view of the laser processing apparatus which concerns on this Embodiment. It is a top view of a wafer. It is a top view for description when the moving direction of a chuck table changes in angle. It is a top view for description when the moving direction of a chuck table changes in angle. It is explanatory drawing which expanded the inside of the visual field of FIG.

  Hereinafter, the present embodiment will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic perspective view of the laser processing apparatus according to the present embodiment. FIG. 2 is a plan view of the laser processing apparatus according to the present embodiment. As shown in FIGS. 1 and 2, the laser processing apparatus 1 relatively moves a laser processing means 2 that irradiates a laser beam and a chuck table 3 that holds a wafer W as a plate-shaped workpiece to move the wafer W. It is configured to process.

  The laser processing apparatus 1 has a rectangular parallelepiped base 4. A chuck table moving mechanism 5 that moves the chuck table 3 in the X direction and the Y direction is provided on the upper surface of the base 4. A standing wall 41 is erected on the rear side of the chuck table moving mechanism 5. An arm portion 42 projects from the front surface of the standing wall portion 41, and the laser processing means 2 and the imaging camera 6 are supported on the arm portion 42 so as to face the chuck table 3.

  The chuck table moving mechanism 5 includes an index feeding means 51 disposed on the upper surface of the base 4 and a processing feed means 52 disposed on the upper portion of the index feeding means 51. The machining feed means 52 is supported by the index feed means 51 from below.

  The index feeding means 51 has a pair of guide rails 51a arranged on the upper surface of the base 4 and parallel to the Y direction, and a Y-axis table 51b that is slidably installed on the pair of guide rails 51a. A nut portion (not shown) is formed on the lower surface side of the Y-axis table 51b, and a ball screw 51c is screwed to the nut portion. A drive motor 51d is connected to one end of the ball screw 51c. The Y-axis table 51b, the machining feed means 52, and the chuck table 3 are indexed and fed in the Y direction, which is the index feed direction, when the drive motor 51d is driven to rotate.

  The processing feed means 52 has a pair of guide rails 52a parallel to the X direction disposed on the upper surface of the Y axis table 51b, and an X axis table 52b slidably installed on the pair of guide rails 52a. . The chuck table 3 is provided on the X-axis table 52b. A nut portion (not shown) is formed on the lower surface side of the X-axis table 52b, and a ball screw 52c is screwed to the nut portion. A drive motor 52d is connected to one end of the ball screw 52c. The X-axis table 52b and the chuck table 3 are processed and fed in the X direction, which is the processing feed direction, when the drive motor 52d is rotationally driven.

  The chuck table 3 is formed in a disc shape, and is rotatably provided on the upper surface of the X-axis table 52b via the θ table 31. On the upper surface of the chuck table 3, an adsorption surface is formed of a porous ceramic material. Four clamp portions 32 are provided around the chuck table 3 via a pair of support arms. The four clamp portions 32 are driven by an air actuator (not shown), whereby the ring frame F around the wafer W is clamped and fixed from four directions.

  FIG. 3 is a plan view of the wafer W. FIG. As shown in FIG. 3, the wafer W is formed in a substantially disk shape. The front surface (upper surface) of the wafer W is partitioned into a plurality of regions by a plurality of intersecting scheduled lines ST, and a device D is formed in each of the partitioned regions. Returning to FIG. 1, the wafer W is attached to an adhesive sheet S stretched on an annular ring frame F with the surface on which the device D is formed facing upward.

  The laser processing means 2 has a laser oscillator 21 provided at the tip of the arm portion 42. The laser oscillator 21 irradiates the laser beam downward, and laser-processes the division line ST (see FIG. 3) of the wafer W held on the chuck table 3. During the irradiation of the laser beam by the laser oscillator 21, the chuck table 3 is processed and fed in the X direction, whereby a processing line L (see FIG. 3) having a groove shape with a predetermined depth is formed on the planned division line ST.

  The imaging camera 6 is constituted by a CCD camera or the like that can image the surface area of the wafer W projected with a microscope at a predetermined magnification within the field of view V (see FIG. 4). The imaging camera 6 images the planned division line ST and the processing line L, and outputs the imaging result to the control means 7.

  The control means 7 performs overall control of each part of the laser processing apparatus 1. The control unit 7 includes a processor that executes various processes, and a storage medium such as a ROM (Read Only Memory) and a RAM (Random Access Memory). For example, the control unit 7 inputs the imaging result output from the imaging camera 6 and controls the driving direction and driving amount of the index feeding unit 51 and the processing feeding unit 52 according to the imaging result.

  The recognition unit 71 of the control means 7 recognizes the difference (separation distance) in the Y direction between the planned division line ST and the processing point on the processing line L from the imaging result of the imaging camera 6. The recognition unit 71 recognizes a difference for each imaging result when there are a plurality of imaging results. In the storage unit 72 of the control means 7, the difference in the Y direction recognized by the recognition unit 71 is stored as a correction value, and when there are a plurality of differences, the correction value is stored for each difference. The control unit 73 of the control unit 7 controls the driving of the index feeding unit 51 so as to correct the locus of the machining line L based on the correction value stored in the storage unit 72. The calculation unit 74 of the control unit 7 calculates the correction value at a predetermined position by substituting the predetermined correction value stored in the storage unit 72 into the functional equation of the linear interpolation method.

  Here, in the laser processing apparatus 1 as in the present embodiment, there is a case in which distortion in which the moving direction of the chuck table 3 and the processing feeding unit 51 changes in angle with respect to the Y direction is inherent to each product. is there. As a specific example, the state shown in FIGS. 4 and 5 is obtained. 4 and 5 are plan views for explaining the case where the moving direction of the chuck table changes in angle. 4 and 5, for convenience of explanation, the division planned line ST is illustrated by two dotted lines, and the device D is omitted. A circle indicated by a symbol V is a field of view V of the imaging camera 6, and a point indicated by a symbol P is a laser beam irradiation position P of the laser oscillator 21. 4 and 5, the guide rail 51a is bent in the direction of the arrow A1 shown in FIGS. 4 and 5, and the indexing feed direction is bent along this direction so as not to be parallel to the Y direction. In this state, when a plurality of processing lines L are formed on the wafer W, the relative positions in the Y direction between the respective processing lines L and the planned division lines ST on which the processing lines L are formed change. Become. For example, the processing line L is formed at the center position in the width direction of the planned division line ST at the position in FIG. 4, but is shifted upward in FIG. A processing line L is formed at the position. Therefore, in the present embodiment, the preparation process described below is performed before processing the product wafer W at the time of shipment or installation of the laser processing apparatus 1.

  In the preparation step, first, as shown in FIG. 1, a dummy wafer W is mounted on the frame F via the adhesive sheet S. The adhesive sheet S side of the wafer W is held by the chuck table 3, and the frame F is held by the clamp portion 32.

  After the wafer W is held, the chuck table 3 is moved in the X direction and the Y direction, and the wafer W is positioned immediately below the imaging camera 6. Next, the surface of the wafer W is imaged by the imaging camera 6, and at least one of the plurality of scheduled division lines ST is detected. Then, the chuck table 3 is rotated via the θ table 31 so that the scheduled division line ST detected by the imaging camera 6 is parallel to the X direction. Thereafter, the chuck table 3 is positioned so that the center position in the width direction of the planned division line ST coincides with the irradiation position of the laser beam emitted from the laser oscillator 21 at an arbitrary position in the X direction on the detected division line ST. Positioned.

  Next, while the laser beam is emitted from the laser oscillator 21, the chuck table 3 is relatively moved in the X direction, whereby the processing line L is laser processed along the planned division line ST parallel to the X direction. During this laser processing, the recognition unit 71 of the control means 7 controls the imaging of the surface of the wafer W by the imaging camera 6 at an arbitrary position in the X direction. In the recognition unit 71, an image of the field of view V of the imaging camera 6 is input as an imaging result. 5 and 6, the recognition unit 71 forms formation edges on both sides in the width direction (Y direction) of the division planned line ST with respect to an arbitrary processing point L1 of the processing line L within the visual field V. Distances y1 and y2 are obtained by image processing or the like. When the difference in the Y direction between the processing point L1 and the center position c in the width direction of the planned division line ST is d, an operation of d = (y1−y2) / 2 is performed, and the difference d is recognized. The The difference d is output to the storage unit 72 and stored as a correction value h in the storage unit 72.

  Each time one processing line L is formed, the wafer W is moved in the Y direction, which is the index feed direction, and stopped by the pitch interval in the Y direction of the planned division line ST. This stop position is set as the index stop position of the index feeding means 51. Thereafter, by repeating the same operation as described above, the processing lines L are sequentially processed on all the division planned lines ST parallel to the X direction. In this processing, all the processing lines L that are the movement range of the index feeding means 51 are imaged by the imaging camera 6, and the difference d between a plurality of locations recognized by the recognition unit 71 is stored as a correction value h in the storage unit 72. Is done. The data of each correction value h stored in the storage unit 72 is stored in a state associated with the position in the Y direction of the scheduled division line ST that is the index stop position. Thus, the preparation process is completed.

  Next, a laser processing method for the product wafer W after completion of the preparation process will be described. In this processing method, first, the product wafer W is held on the chuck table 3 in the same manner as in the preparation step. Then, the chuck table 3 is positioned so that the irradiation position of the laser beam coincides with the center position in the width direction of the planned division line ST. In this positioning, the control unit 73 controls the driving of the indexing feeding means 51, and the chuck is corrected by the correction value h stored in the storage unit 72 in association with the Y-direction position (indexing stop position) of the corresponding division planned line ST. The position of the table 3 in the Y direction is displaced. Thereby, the difference d in the Y direction of the processing line L in the preparation process is corrected, and laser processing is performed so that the processing line L coincides with the center position in the width direction of the division planned line ST parallel to the X direction.

  Each time one processing line L is formed, the wafer W is moved in the Y direction, which is the index feed direction, and stopped by the pitch interval in the Y direction of the planned division line ST. In this way, after the processing lines L are formed on all the division lines ST parallel to the X direction, the chuck table 3 is rotated by 90 ° via the θ table 31. Then, among the grid-like division planned lines ST, the division planned lines ST in which the processing line L is not formed are made parallel to the X direction. From this state, the processing lines L are formed on all the planned division lines ST parallel to the X direction in the same manner as described above, and the processing lines L are formed on all the planned division lines ST in a lattice shape.

  In addition, when the wafer W used in the preparation process is processed with the wafer W in which the number of the division planned lines ST is changed, the correction value h is stored in association with the division planned line ST serving as an index stop position. There are no scheduled division lines ST (hereinafter referred to as “line ST without correction value”). In this case, the calculation unit 74 searches the correction value h stored in the storage unit 72 for the two correction values h that are closest to the no correction value line ST in the Y direction. Then, the corrected correction value h of the line ST without correction value is calculated by substituting the searched correction value h into the functional equation of the linear interpolation method.

  As described above, according to the laser processing apparatus of the present embodiment, it is possible to perform control so as to correct the position in the Y direction of the processing line L at each of the planned division lines ST that are the index stop positions. As a result, even if the index feed direction of the index feed means 51 is bent and the angle changes with respect to the Y direction, the laser machining can be performed so that the machining lines L coincide with each of all the scheduled division lines ST. . As a result, the processing accuracy for the wafer W can be kept good, and the quality of the device D can be improved. In addition, since the indexing feeding means 51 supports the machining feeding means 52 from below, it becomes easier to maintain the relative angle between the indexing feeding and the machining feeding compared to the case where each is installed at a different position of the base 4. This can contribute to improvement of processing accuracy.

  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, the processing target of the above embodiment may be a semiconductor product package, ceramic, glass, sapphire, a silicon-based substrate, various electrical components, or a plate-shaped workpiece such as various processing materials that require micron-order accuracy. .

  The index feed direction is not parallel to the Y direction. In addition to the state of bending in the arrow A1 direction shown in FIG. 4 and FIG. The locus of the machining line L can be corrected according to the form.

  As described above, the present invention has an effect that it is possible to suppress a decrease in processing accuracy even when the angle in the indexing feeding direction by the indexing feeding means is changed. It is useful for an apparatus for laser processing a line.

DESCRIPTION OF SYMBOLS 1 Laser processing apparatus 2 Laser processing means 3 Chuck table 6 Imaging camera 21 Laser oscillator 51 Index feed means 52 Processing feed means 71 Recognition part 72 Storage part 73 Control part 74 Calculation part L Processing line L1 Processed point ST Divided line W Wafer (Plate work)

Claims (2)

A chuck table for holding a plate-like workpiece with a division schedule line;
A laser processing means comprising a laser oscillator for irradiating a laser beam along the scheduled division line of the plate-like workpiece held by the chuck table;
An imaging camera that images a machining line that is disposed apart from the laser oscillator in the machining feed direction and laser-processes the division-scheduled line of the plate-like workpiece held by the chuck table with a laser oscillator;
Processing feed means for processing and feeding the chuck table in the X direction as the processing feed direction;
An indexing feeding means for supporting the machining feeding means from below and indexing and feeding in the Y direction which is the indexing feeding direction;
When the movement direction of the chuck table and the machining feed means changes with respect to the Y direction by the index feed by the index feed means, a plurality of index stop positions by the index feed means in the movement range of the index feed means, respectively. In the Y direction between the machining point where the laser oscillator laser-processed the plate-like workpiece at the plurality of index stop positions and the division planned line from the imaging result of the imaging camera. A recognition unit that recognizes the difference;
A storage unit that stores, as a correction value, a difference in the Y direction recognized by the recognition unit for each of the plurality of index stop positions;
A control unit for controlling the driving of the index feeding means so as to correct the position of the processing line at each index stop position based on the correction value stored in the storage unit;
The laser processing apparatus provided with.   When the storage unit does not store the correction value for the predetermined index stop position by the index sending means, the two closest to the predetermined index stop position among the plurality of correction values stored by the storage unit The laser processing apparatus according to claim 1, further comprising a calculating unit that calculates the correction value at the predetermined index stop position using the two correction values and a linear interpolation method.

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