JP2010214413A - Laser processing apparatus with alignment correction function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser processing apparatus for correcting a processing position with high precision, even if an irradiation position of a laser beam is changed according to the effect of heat generated from the processing apparatus, when processing a workpiece with the laser. <P>SOLUTION: The processing apparatus for processing the workpiece by irradiating with the laser beam is provide with a first camera and second camera, and a step of checking and correcting a spot position irradiated with the laser before the laser processing with the respective cameras, is provided in the processing step. Therefore, since the position in which the workpiece or a separately positioned dummy workpiece is irradiated with the laser, is checked and corrected with the first camera and second camera before processing, even if the position irradiated with the laser is changed according to thermal expansion or the like of the laser processing apparatus by the heat generated during the laser processing, the precision of the position in the laser processing is improved. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an apparatus for processing a workpiece such as a semiconductor wafer with a laser.

As a technique for irradiating a workpiece such as a semiconductor wafer with laser light, Patent Document 1 discloses a laser processing apparatus including a CCD camera and a processing method.
Patent Document 1 aims to provide a laser processing apparatus that simultaneously performs a function of observing a substrate surface and condensing a laser beam at an arbitrary position inside the substrate. A condensing point at a predetermined depth inside the substrate from the substrate surface. An optical system equipped with an afocal optical system for condensing the laser light inside the substrate and an automatic focusing mechanism for observing the substrate surface when the internal processing region is formed by condensing the laser light on With the optical system provided and the objective lens shared by the two optical systems, the adjustment of the laser beam condensing position inside the substrate and the adjustment of the observation focus on the irradiated surface of the substrate surface by the automatic focusing mechanism are respectively It can be adjusted independently.
Further, when laser processing a workpiece such as a semiconductor wafer, the workpiece has been aligned (confirmed) by an alignment camera provided in a processing apparatus before laser processing.

JP 2006-147817 A

Even if the position of the object to be measured is confirmed while imaging with the alignment camera provided in the processing device before laser processing, the irradiation position of the laser irradiation light and the position of the alignment camera are at the room temperature where the processing device is installed. The position is relatively shifted due to thermal effects such as changes, heat generated from the camera, and heat generated from a drive motor that moves and positions a workpiece provided in the processing apparatus. Therefore, even if the position of the workpiece is confirmed by the alignment camera as in the prior art, the machining position of the first workpiece is accurate, but as the number of workpieces increases, the heat generated during machining increases the alignment with the laser irradiation position. The relative position of the camera changes and the processing position changes. Accordingly, in order to maintain the accuracy of the machining position for all the large numbers of workpieces, some position correction means is necessary. There is no laser processing apparatus provided with means for correcting the relative position of the laser irradiation position due to the heat generation during the conventional processing and the alignment camera.
In addition, the laser processing method disclosed in Patent Document 1 uses a CCD camera to focus laser light on a semiconductor wafer when cleaving the semiconductor wafer, images the surface of the semiconductor wafer, and collects it using image signals from the camera. The optical optical system is moved up and down to focus the laser irradiation light on the semiconductor wafer. Therefore, the purpose of installing the CCD camera is different from the purpose of correcting the position of the processing position.
An object of the present invention has been made to solve the above-described problems, and a laser beam irradiation position and means for confirming the position due to the thermal effect of heat generated during processing when a workpiece is laser processed. Another object of the present invention is to provide a laser processing apparatus capable of correcting a processing position and performing high-precision laser processing even if the relative position of a confirmation device is shifted.

A laser processing apparatus according to a first aspect of the present invention for achieving the above object is a laser processing apparatus that processes a workpiece by irradiating the workpiece with laser light, and has one or more cameras. Before performing laser processing, the method includes a step of irradiating a workpiece or the like with a laser beam in a spot shape, confirming the position of the laser spot with any of the cameras, and correcting the position.
A laser processing apparatus according to a second aspect of the present invention includes the first camera and the second camera according to the first aspect of the present invention. Before laser processing, the laser beam is irradiated to a workpiece or the like in a spot shape, and the laser is processed by the first camera. A step of confirming the position of the laser spot and correcting the position, and a step of irradiating the workpiece with a laser beam in the form of a spot before performing laser processing and confirming the position of the laser spot with a second camera and correcting the position. It is characterized by having.
According to a third aspect of the present invention, there is provided a laser processing apparatus according to the second aspect, wherein the optical axes of the first camera and the second camera are provided at positions separated from the axial direction of irradiating the laser light by a certain distance.
According to a fourth aspect of the present invention, there is provided a laser processing apparatus according to the third aspect, further comprising a third camera in which the optical axis of the camera is the same as or close to the axis that irradiates the laser beam.
According to a fifth aspect of the present invention, there is provided the laser processing apparatus according to the second aspect, wherein either one of the first camera and the second camera is provided such that the optical axis of the camera is separated from the axial direction of the laser beam by a certain distance. The other is characterized in that the optical axis of the camera is the same as or close to the axis for irradiating the laser beam.
According to a sixth aspect of the present invention, there is provided a laser processing apparatus according to any one of the first to fifth aspects, wherein the step of correcting the position by the camera is performed for every workpiece.
According to a seventh aspect of the present invention, there is provided a laser processing apparatus according to any one of the first to fifth aspects, wherein the step of performing the position correction by the camera is performed for every predetermined number of workpieces.
According to an eighth aspect of the present invention, there is provided a laser machining apparatus according to any one of the first to seventh aspects, wherein the step of correcting the position by the camera is performed by irradiating a dummy workpiece separately from the workpiece with a laser spot. It is characterized by doing.
According to a ninth aspect of the present invention, there is provided the laser processing apparatus according to any one of the first to eighth aspects, wherein the workpiece is a semiconductor wafer.

According to the first invention, the laser beam is irradiated on the workpiece or the dummy workpiece before laser processing, and the laser irradiation position is confirmed and corrected by one or more cameras. Even if the laser irradiation position and the relative position of the camera change due to heat, position correction can be performed, so that processing position data can be corrected and laser processing can be performed at an accurate position. In addition, since the position can be corrected by one camera, the device configuration is easy.
According to the second invention, the laser beam is irradiated to the workpiece or the dummy workpiece before laser processing, and the laser irradiation position is confirmed and corrected by the first camera and the second camera. By observing the position deviation of the camera position due to the thermal effect by observing with one camera and the second camera, the position deviation of the laser irradiation position can be calculated from the result of the correction calculation. Can be laser processed.
According to the third invention, since the respective cameras are installed at positions spaced apart from each other by a certain distance in the axial direction in which the first camera and the second camera are irradiated with laser light, the device configuration is easy. The first camera and the second camera are used as alignment cameras, and are arranged in parallel with the axis for irradiating the laser beam, or the first camera and the second camera 2 are arranged on both sides with respect to the axis for irradiating the laser beam. It is also possible to do. Therefore, it is possible to calculate the position correction by taking into account the difference in the location of the thermal effect that occurs in the laser processing device, and the position correction calculation taking into account the thermal effect of the processing device when the object to be measured becomes large can do.
According to the fourth invention, the first camera and the second camera are provided to correct the laser irradiation position, and the laser irradiation trace for confirming the position by the third camera is observed, or the position of the workpiece before laser processing Therefore, the laser processing position can be set accurately.
According to the fifth aspect of the invention, either the first camera or the second camera is located at a certain distance from the axial direction for irradiating the laser beam, and the other one is an axis for irradiating the laser beam. Since the irradiation trace at the position irradiated with the laser can be observed, the laser processing position can be set more accurately.
According to the sixth invention, the accuracy of the laser processing position is improved by performing the step of confirming the laser irradiation position and correcting the position before the laser processing for every workpiece.
According to the seventh aspect of the invention, the step of confirming the laser irradiation position and correcting the position before laser processing is performed for every predetermined number of workpieces, so that the tact time is shortened while ensuring the accuracy of the laser processing position. be able to.
According to the eighth aspect, since confirmation by laser irradiation before laser processing is performed on the dummy substrate, the product yield is improved in the case where the workpiece cannot be irradiated with laser.
According to the ninth aspect, when the workpiece is a semiconductor wafer, the processing accuracy and yield of the processed chips can be improved.

It is drawing for demonstrating the shape of the semiconductor wafer which is a to-be-processed object. It is drawing explaining a dummy substrate. It is drawing explaining the structure of a laser processing apparatus. It is a flowchart of a laser dicing process. It is drawing explaining Embodiment 1 of a laser processing apparatus. It is drawing explaining Embodiment 2 of a laser processing apparatus. It is drawing explaining Embodiment 2 of a laser processing apparatus. It is drawing explaining Embodiment 3 of a laser processing apparatus. It is drawing explaining Embodiment 3 of a laser processing apparatus. It is drawing explaining Embodiment 4 of a laser processing apparatus.

  An embodiment of the laser processing apparatus of the present invention will be described by taking as an example a case where a workpiece is subjected to laser dicing processing on a semiconductor wafer.

<1> Workpiece (Semiconductor Wafer) and Method for Attaching the Workpiece FIG. 1 shows a state where a sapphire wafer W (hereinafter referred to as a wafer) is attached to an adhesive sheet S as one embodiment of the work piece according to the present invention. Show. The thickness of the wafer W is a substrate having a circular thin plate shape of about 100 to 400 μm. In addition, a plurality of small sections (chips) divided into a rectangular shape with white having a certain line width are formed on the wafer. In addition, electrodes having various shapes are formed on the chip.
As described above, about 20 wafers and rings R attached to the adhesive sheet S are stored in a cassette, and are loaded and unloaded onto the XY table 10 of the laser processing apparatus by the handling apparatus.

<2> Dummy Substrate FIG. 2 shows the dummy substrate 11. When correcting the position of the laser irradiation position before laser processing, laser irradiation for position correction cannot be performed on the product wafer, so a horizontally long rectangular dummy substrate 11 is attached on the XY table 10. is there. Laser irradiation is performed on the dummy substrate, and the irradiation position is confirmed and corrected by a camera (alignment camera or observation camera) described later. As this dummy substrate, a mirror-finished surface of a silicon wafer is used. Further, an additional dummy substrate 12 used in another type of laser processing apparatus can be provided on the XY table. (See the two-dot chain line portion 12 in FIG. 2)

<3> Configuration of Laser Processing Apparatus The configuration of the laser processing apparatus 100 of the present invention will be described with reference to FIG. The laser processing apparatus of the present invention comprises the following parts.
(1) XY table 10
The wafer shown in FIG. 1 is placed on a table and has an X-axis movement mechanism and a Y-axis movement mechanism, and the wafer on the table 10 can be positioned and moved to any position within the range of the movement stroke of each axis. . Further, the XY table has a function of fixing the ring and the wafer attached to the adhesive sheet. The ring is fixed by vacuum suction.
(2) Laser controller 20
Controls the light intensity and the like for laser irradiation.
(3) Laser irradiation unit 30
It is fixed to the laser processing apparatus 100 and irradiates a laser beam having a predetermined intensity according to an instruction from the laser controller 20.
(4) Observation camera (first camera) 40
The optical axis of the observation camera is the same as or close to the axis that irradiates the laser beam of the laser irradiation unit in the laser processing apparatus. A pair of mirrors are provided at a certain distance from the wafer surface, which is a workpiece, in the direction of the laser irradiation unit 30, and an observation camera is provided thereabove. A CCD camera can be used as the camera.
(5) Alignment camera (second camera) 50
The alignment camera is fixedly arranged with a certain distance between the optical axis of the alignment camera and the axis that irradiates the laser beam of the laser irradiation unit in the laser processing apparatus. A CCD camera can be used as the camera.
(6) Image processing controller 60
The focus adjustment of the image of the wafer surface imaged by the alignment camera and the observation camera, determination of whether or not the laser irradiation position imaged by the camera coincides with the optical axis of the camera, and the like are performed.
(7) Control device 70
A PLC (sequencer) and the like are built in and the entire apparatus is also controlled. The laser irradiation position imaged by the alignment camera and the observation camera is moved so as to coincide with the optical axis of each camera, and the position correction at the time of laser processing is calculated. Further, an oscillation signal is transmitted to the laser controller. A computer such as a personal computer can also be used as the control device.

<4> Process of Laser Dicing Process FIG. 4 is a flowchart for explaining a process of dicing a silicon wafer into individual element chips. The machining process will be described with reference to the flowchart of FIG. In this machining process, the step of correcting the position of the laser irradiation position (S5) before laser machining will be described in detail separately. In addition, the ring in a figure is a thing of the state of FIG. 1 which affixed the ring R and the wafer W to the sheet | seat S. FIG.
(1) Set a cassette in the processing apparatus. (S1)
(2) Pull out the wafer (including the ring) attached to the sheet from the cassette. (S2)
(3) The shape of the wafer is recognized by the shape recognition camera. (S3)
(4) The wafer (including the ring) attached to the sheet is placed on the XY table. (S4)
(5) The laser irradiation trace is observed and the position is corrected and calculated. (S5)
5-1) The XY table is moved, the laser irradiation unit is moved onto the dummy substrate, and laser irradiation is performed.
5-2) The laser irradiation trace is observed with the first camera (observation camera), and the position is corrected and calculated.
5-3) The laser irradiation trace is observed with the second camera (alignment camera), and the position is corrected and calculated.
(6) Position correction (alignment) is performed based on the correction calculation result. (S6)
(7) The position for dicing is visually confirmed. (S7)
(8) The wafer is diced by moving the XY moving table while irradiating the laser. (S8)
(9) The wafer (including the ring) attached to the processed sheet is stored in the cassette. (S9)

  Note that the position correction step S5 may be performed every time one wafer is used. However, in order to shorten the tact time, it may be performed for every predetermined number of wafers. However, in this case, a threshold is provided for the amount of positional deviation observed by the alignment camera before laser processing (for example, XB and YB in FIGS. 5 and 7 described later), and when the threshold is exceeded, steps S5 to S6 are performed. It is preferable to do so. The threshold value of the observed misregistration amount is set in a PLC or the like in a control apparatus that controls the entire apparatus, and the set value may be changed when the type or size of the wafer is changed.

<5> Method for correcting the position of the laser irradiation position (step S5)
First, the step (S5) of correcting the position of the laser irradiation position using the first camera as an observation camera and using the second camera as an alignment camera for position correction will be described.
(1) The table is moved to perform position correction. At the same time, the height position (Z axis) of laser irradiation is also moved. The X and Y axes are driven to move the laser irradiation position onto the dummy substrate on the XY table, and the Z axis is driven to adjust the height position so that the laser is irradiated onto the dummy substrate on the upper surface of the table. (S51)
(2) Irradiate laser. The laser irradiation power is automatically changed. The table X-axis and Y-axis current values of the irradiated position (A) are stored. (S52)
(3) The shape of the laser irradiation trace is registered in the image processing controller with the first camera (observation camera). Registration only needs to be performed once for the initial setting. (S53)
(4) Move the table to the center position of the first camera (observation camera) with the irradiation mark. Each of the X axis and Y axis is driven, and an arithmetic processing is performed by the image processing controller, and the table X axis and Y axis current values of the center position (A ′) are stored. (S54)
(5) The position relation value between the position (A) and the position (A ′) is internally calculated by a PLC (sequencer) in the overall control device, and the difference between the X axis and the Y axis is the laser irradiation position / first camera offset value. Stored as (correction value). Thereby, the XY coordinates of the center position of the observation camera are specified. (S55)
(6) The irradiation mark is moved to the center position (B) of the initial setting of the second camera (alignment camera). Further, each of the X axis and Y axis is driven, and an arithmetic processing is performed by the image processing controller, and the table X axis and Y axis current values of the center position (C) of the true laser irradiation mark are stored. (S56)
(7) The position relationship value between the position (A) and the position (C) is internally calculated by a PLC (sequencer) in the overall control device, and the difference between the X axis and the Y axis is calculated as the offset value between the laser irradiation position and the second camera ( Correction value). In the case of laser processing, position correction is performed with this offset value. (S57)
(8) End of calibration (end of position correction) (S58)

<6> Embodiment 1 of a laser processing apparatus (position correction of a laser irradiation position)
The first embodiment of the laser processing apparatus of the present invention uses only one first alignment camera 42 for position correction. This embodiment will be described with reference to FIG. FIG. 5 is a diagram for explaining a position correction method using an alignment camera. FIG. 5A is a block diagram of position correction. FIG. 5B is an alignment camera image 1 at the time of position correction, and FIG. 5C is an alignment camera image 2.

<6-1> Position Correction by Alignment Camera (1) The XY table is moved by the control device and moved to the laser irradiation position (on the dummy substrate). (Dashed flow 1 in the drawing)
(2) The laser is oscillated from the control device. Send a signal from the controller to the laser controller. (Solid flow 2 in the drawing)
(3) Laser irradiation is instructed from a laser controller. (Solid line flow 3 in the drawing)
(4) The XY table is moved from the control device and moved by Xb and Yb in the figure so that the laser irradiation mark is at the center of the alignment camera. (Dashed flow 1 in the drawing)
Here, Xb and Yb are set values unique to the apparatus from the laser irradiation position to the center position of the first alignment camera. At this time, the laser irradiation position and the relative position of the alignment camera deviate from the laser irradiation mark (XB and YB in FIG. 5B) due to thermal effects.
(5) The irradiation trace is confirmed with the first alignment camera. (Refer to the solid flow 4 in the drawing, FIG. 5 (b))
(6) The amount of deviation between the irradiation mark and the center position of the first alignment camera is transferred from the image processing controller to the control device. (Flow 5 of solid line in the drawing)
(7) The irradiation mark is moved from the control device to the center position of the first alignment camera by XB and YB in the drawing. (Dashed flow 1 in the drawing)
(8) Check if the irradiation mark is at the center of the camera. (See Fig. 5 (c))
(9) The current position (C) of the X axis and Y axis is stored.
(10) The difference between the position (B) and the position (C) is stored and set as a correction value.
Alignment camera offset (X coordinate) = XB
Alignment camera offset amount (Y coordinate) = YB

<6-2> Correction Calculation of Laser Irradiation Position The X coordinate and Y coordinate of the position coordinate for actual processing are corrected and calculated from the position correction result (XB, YB) by the alignment camera as follows.
Machining position command value (X coordinate) = (X coordinate in machining program) + XB
Machining position command value (Y coordinate) = (Y coordinate in machining program) + YB

<7> Embodiment 2 of laser processing apparatus (position correction of laser irradiation position)
The second embodiment of the laser processing apparatus of the present invention uses an observation camera 41 (first camera) and an alignment camera (second camera) 51. This embodiment will be described with reference to FIGS. FIG. 6 is a diagram for explaining a method for confirming an irradiation mark and a laser processing position by an observation camera (first camera). FIG. 6A is a block diagram. FIG. 6B shows an image 1 of the observation camera when the irradiation mark is confirmed, and FIG. 6C shows an observation camera image 2. FIG. 7 is a diagram for explaining a position correction method using an alignment camera (second camera). FIG. 7A is a block diagram of position correction. FIG. 7B is an alignment camera image 1 at the time of position correction, and FIG. 7C is an alignment camera image 2.
<7-1> Confirmation of irradiation mark and laser irradiation position by observation camera (see FIG. 6)
(1) The XY table is moved by the control device and moved to the laser irradiation position (on the dummy substrate). (Dashed flow 1 in the drawing)
(2) The laser is oscillated from the control device. Send a signal from the controller to the laser controller. (Solid flow 2 in the drawing)
(3) Laser irradiation is instructed from a laser controller. The current position (A) of the X axis and Y axis is stored. (Solid line flow 3 in the drawing)
(4) The irradiation trace is confirmed with an observation camera (first camera). (Refer to the solid flow 4 in the drawing, FIG. 6B)
(5) The amount of deviation between the irradiation mark and the center position of the observation camera is transferred from the image processing controller to the control device. (Flow 5 of solid line in the drawing)
(6) The irradiation mark is moved from the control device to the observation camera center position by XA and YA in the figure.
(7) Check if the irradiation mark is in the center of the camera. (See FIG. 6 (c))
(8) The current position (A ′) of the X axis and Y axis is stored.
(9) The difference between the position (A) and the position (A ′) is stored and set as a correction value.
Observation camera offset (X coordinate) = XA
Observation camera offset (Y coordinate) = YA

  With this observation camera offset value, the processing position of the laser processing apparatus and the center position of the observation camera being processed can be relatively confirmed.

<7-2> Position correction by alignment camera (second camera) (see FIG. 7)
(1) The XY table is moved from the control device, and is moved by Xb and Yb in the drawing so that the laser irradiation trace is at the center of the alignment camera. (Dashed flow 1 in the drawing)
Here, Xb and Yb are set values specific to the apparatus from the laser irradiation position to the alignment camera center position. At this time, the laser irradiation position and the relative position of the alignment camera deviate from the laser irradiation mark (XB and YB in FIG. 7B) due to thermal effects.
(2) An irradiation mark is confirmed with an alignment camera (second camera). (Refer to the solid line flow 2 in the drawing, FIG. 7B)
(3) The amount of deviation between the irradiation mark and the center position of the alignment camera is transferred from the image processing controller to the control device. (Solid line flow 3 in the drawing)
(4) The irradiation mark is moved from the control device to the center position of the alignment camera by XB and YB in the figure. (Dashed flow 1 in the drawing)
(5) Check if the irradiation mark is in the center of the camera. (See Fig. 7 (c))
(6) The current position (C) of the X axis and Y axis is stored.
(7) The difference between position (B) and position (C) is stored and set as a correction value.
Alignment camera offset (X coordinate) = XB
Alignment camera offset amount (Y coordinate) = YB

<7-3> Correction Calculation of Laser Irradiation Position The X coordinate and Y coordinate of the position coordinate for actual processing are corrected and calculated from the position correction result (XB, YB) by the alignment camera as follows.
Machining position command value (X coordinate) = (X coordinate in machining program) + XB
Machining position command value (Y coordinate) = (Y coordinate in machining program) + YB

<8> Embodiment 3 of laser processing apparatus (position correction of laser irradiation position)
Embodiment 3 of the laser processing apparatus of the present invention uses two alignment cameras. Two alignment cameras are arranged in parallel on one side with respect to the optical axis of the laser irradiation light. This embodiment will be described with reference to FIGS. In the present embodiment, the step of registering the shape of the laser irradiation mark by the observation camera in S53 of the step (S5) in the image processing controller is not provided. An observation camera may be provided as the third camera if registration of the shape of the laser irradiation trace by the observation camera and confirmation of the initial processing position are necessary.

  FIG. 8 is a diagram for explaining a method of position correction by the first alignment camera (first camera) 42. FIG. 8A is a block diagram of position correction. FIG. 8B is a first alignment camera image 1 during position correction, and FIG. 8C is a first alignment camera image 2. FIG. 9 is a diagram for explaining a method of position correction by the second alignment camera (second camera) 51. FIG. 9A is a block diagram of position correction. FIG. 9B is a second alignment camera image 1 during position correction, and FIG. 9C is a second alignment camera image 2.

<8-1> Position correction by the first alignment camera (first camera) (see FIG. 8)
(1) The XY table is moved by the control device and moved to the laser irradiation position (on the dummy substrate). (Dashed flow 1 in the drawing)
(2) The laser is oscillated from the control device. (A signal is sent from the control device to the laser controller.) (Solid flow 2 in the drawing)
(3) Laser irradiation is instructed from a laser controller. (Solid line flow 3 in the drawing)
(4) The XY table is moved from the control device, and is moved by Xd and Yd in the drawing so that the laser irradiation trace is at the center of the first alignment camera. (Dashed flow 1 in the drawing)
Here, Xd and Yd are setting values unique to the apparatus from the laser irradiation position to the first alignment camera center position. At this time, the laser irradiation position and the relative position of the alignment camera deviate from the laser irradiation mark (XD and YD in FIG. 8B) due to thermal effects.
(5) The irradiation trace is confirmed with the first alignment camera. (Refer to the solid flow 4 in the drawing, FIG. 8 (b))
(6) The amount of deviation between the irradiation mark and the center position of the second alignment camera is transferred from the image processing controller to the control device. (Flow 5 of solid line in the drawing)
(7) The irradiation mark is moved from the control device to the center position of the second alignment camera by XD and YD in the drawing. (Dashed flow 1 in the drawing)
(8) Check if the irradiation mark is at the center of the camera. (See Fig. 8 (c))
(9) The current position (E) of the X axis and Y axis is stored.
(10) The difference from the position (D) to the position (E) is stored and set as a correction value.
Second alignment camera offset amount (X coordinate) = XD
Second alignment camera offset amount (Y coordinate) = YD

<8-2> Position correction by the second alignment camera (second camera) (see FIG. 9)
(1) The XY table is moved from the control device, and the Xf and Yf are moved in the figure so that the laser irradiation mark becomes the center of the second alignment camera. (Dashed flow 1 in the drawing)
Here, Xf and Yf are set values unique to the apparatus from the laser irradiation position to the center position of the second alignment camera. At this time, the laser irradiation position and the relative position of the alignment camera deviate from the laser irradiation mark (XF and YF in FIG. 9B) due to thermal effects.
(2) The irradiation trace is confirmed with the second alignment camera. (Refer to the flow 2 in the solid line in the drawing, FIG. 9B)
(3) The amount of deviation between the irradiation mark and the center position of the second alignment camera is transferred from the image processing controller to the control device. (Solid line flow 3 in the drawing)
(4) The irradiation mark is moved from the control device to the center position of the alignment camera by XF and YF in the figure. (Dashed flow 1 in the drawing)
(5) Check if the irradiation mark is in the center of the camera. (See Fig. 9 (c))
(6) The current position (G) of the X axis and Y axis is stored.
(7) The difference from position (F) to position (G) is stored and set as a correction value.
Second alignment camera offset amount (X coordinate) = XF
Second alignment camera offset amount (Y coordinate) = YF

<8-3> Laser irradiation position correction calculation Actual from position correction results (XD, YD) by the first alignment camera (first camera) and position correction results (XF, YF) by the second alignment camera (second camera) The X coordinate and the Y coordinate of the position coordinate for processing into the following can be corrected and calculated as follows.
(1) The position is corrected and calculated only by the correction amount by the first alignment camera.
Command value of machining position (X coordinate) = (X coordinate in machining program) + XD
Processing position command value (Y coordinate) = (Y coordinate in machining program) + YD
(2) The position is corrected and calculated only by the correction amount by the second alignment camera.
Machining position command value (X coordinate) = (X coordinate in machining program) + XF
Machining position command value (Y coordinate) = (Y coordinate in machining program) + YF
(3) Correction calculation using the first alignment camera is used for a certain range of the movement amount of the XY axes, and correction calculation using the second alignment camera is used for the movement amount of the XY axes outside the certain range. To do.
(4) Correction calculation is performed using the average value of the correction amount of the first alignment camera and the correction amount of the second alignment camera as the correction amount.

In the third embodiment, two alignment cameras are used, and the position correction calculation is performed for the correction amount of each alignment camera by the above four methods. When only the correction amount of one of the alignment cameras is used as in (1) and (2) above, the other camera may be used for the purpose of observing the entire wafer roughly.
Further, by adopting the position correction calculation method as in the above (3) and (4), it is possible to take into account the local difference in the thermal influence of the processing apparatus. Further, when the workpiece becomes larger, the apparatus becomes larger and the thermal influence becomes great. However, the position accuracy of laser processing can be further improved by such a position correction calculation method.

<9> Fourth Embodiment of Position Correction of Laser Irradiation Position
Embodiment 4 of the laser processing apparatus of the present invention is a form in which two alignment cameras are used as shown in FIG. 10 and one is arranged on each side of the optical axis of the laser irradiation light. The position correction method in this embodiment can be performed in the same manner as in the third embodiment. By adopting such a configuration, the distance between the first alignment camera 42 and the second alignment camera 51 can be made as long as possible. Therefore, since the change in position can be observed and corrected by the influence of heat within the range of the movement stroke of the laser processing apparatus, the accuracy of position correction can be further improved. In this embodiment, when the axis movement stroke for moving the second alignment camera to the laser irradiation mark on the dummy substrate is insufficient due to the apparatus configuration, the dummy for the second alignment camera is positioned at the two-dot chain line position in FIG. A substrate 12 may be provided, and laser irradiation for position correction may be performed by the second alignment camera.

  In the present embodiment, the step of registering the shape of the laser irradiation mark by the observation camera in S53 of the step (S5) in the image processing controller is not provided. If registration of the shape of the laser irradiation mark by the observation camera and confirmation of the initial processing position are necessary, an observation camera may be provided as the third camera.

  The laser processing apparatus of the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

W wafer S adhesive sheet R ring 10 XY table 11 dummy substrate 12 dummy substrate 20 laser controller 30 laser irradiation unit 40 first camera 41 observation camera 42 first alignment camera 50 second camera 51 second alignment camera 60 image processing controller 70 control apparatus
100 Laser processing equipment

Claims (9)

A laser processing apparatus for processing a workpiece by irradiating the workpiece with laser light,
Have one or more cameras,
A laser processing apparatus comprising: a step of irradiating a workpiece or the like with a laser beam in a spot form before laser processing, and confirming the position of the laser spot with any of the cameras and correcting the position. Having a first camera and a second camera,
Before laser processing, a step of irradiating a workpiece or the like with a laser in a spot shape, confirming the position of the laser spot with a first camera, and correcting the position;
Before laser processing, irradiating a workpiece or the like with a laser beam in a spot shape, confirming the position of the laser spot with a second camera, and correcting the position;
The laser processing apparatus according to claim 1, comprising:   3. The laser processing apparatus according to claim 2, wherein the optical axes of the first camera and the second camera are provided at a position separated from the axial direction of laser light irradiation by a certain distance.   The laser processing apparatus according to claim 3, wherein a third camera is provided in which an optical axis of the camera is the same as or close to an axis on which laser light is irradiated.   In either the first camera or the second camera, the optical axis of the camera is provided at a position away from the axial direction of laser light irradiation, and the other one of the optical axis of the camera emits laser light. The laser processing apparatus according to claim 2, wherein the laser processing apparatus is the same as or close to the axis.   The laser processing apparatus according to any one of claims 1 to 5, wherein the step of correcting the position by the camera is performed for every workpiece.   The laser processing apparatus according to claim 1, wherein the position correction by the camera is performed for each predetermined number of workpieces.   The laser processing according to any one of claims 1 to 7, wherein the step of correcting the position by the camera is performed by irradiating a dummy workpiece separately from the workpiece with a laser spot. apparatus. The laser processing apparatus according to claim 1, wherein the workpiece is a semiconductor wafer.

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