JP6552948B2 - Wafer processing method and processing apparatus - Google Patents

Description

  The present invention relates to a wafer processing method and a processing apparatus for forming a laser processing hole corresponding to an electrode pad of a device disposed on a workpiece such as a semiconductor wafer.

  In the semiconductor device manufacturing process, a plurality of regions are partitioned by dividing lines called streets arranged in a lattice pattern on the surface of a substantially wafer-shaped semiconductor wafer, and devices such as ICs, LSIs, etc. are partitioned in the partitioned regions. Form Then, the semiconductor wafer is cut along the streets to divide the area where the device is formed, thereby manufacturing individual semiconductor chips.

  In order to reduce the size and increase the functionality of an apparatus, a module structure has been proposed in which a plurality of devices are stacked and electrode pads (also referred to as bonding pads) provided in the stacked devices are connected. In this module structure, a via hole (laser processing hole) reaching the electrode pad is formed by irradiating a laser beam at a portion of the semiconductor wafer where the electrode pad is provided, and this via hole (laser processing hole) is connected to the electrode pad. This is a structure in which a conductive material such as aluminum is embedded (see, for example, Patent Document 1).

JP 2008-062261 A

  In order to form the via hole, it is necessary to irradiate a plurality of pulse laser beams at one place, and in order to improve the production efficiency, it is necessary to increase the repetition frequency of the pulse laser beams. However, when the pulse laser beam is continuously irradiated to one place at a high repetition frequency, there is a problem that the heat buildup causes the wafer to be cracked and the quality of the device is deteriorated.

  In addition, although there are differences depending on the device to be manufactured, there are some in which the repetition frequency of the pulsed laser beam used for processing is limited (for example, 10 kHz) so as not to cause cracks by via hole processing. Therefore, a technical problem to be solved by the present invention is to provide a wafer processing method and a laser processing apparatus capable of simultaneously forming via holes at a plurality of locations while maintaining a limited maximum repetition frequency of a pulsed laser beam. It is.

  In order to solve the above-mentioned main technical problem, according to the present invention, there is provided a wafer processing method in which a plurality of devices are partitioned by lines to be divided and formed on a surface, together with position information of each device on the wafer, A position information storing step for storing position information in each device of a plurality of electrode pads formed in the device, and four devices adjacent to each other as one group are arranged at the same position in each device. An elliptical trajectory generating step for generating an elliptical trajectory including a circle passing through the four electrode pads, and a pulse laser beam irradiating means irradiating a position corresponding to the four electrode pads while drawing the elliptical trajectory. The ellipse passes through the laser beam irradiation step and the position corresponding to the four electrode pads to be processed next. The electrode relative to the wafer is sequentially subjected to the laser beam irradiation step and the elliptical orbit positioning step while the elliptical orbit positioning step for positioning the orbit, the wafer, and the pulsed laser beam irradiation means are relatively processed and fed. Provided is a processing method of a wafer to be subjected to via hole processing for forming a via hole corresponding to a pad.

  In the laser beam irradiation step, it is preferable to perform via hole processing in which a plurality of pulse laser beams are irradiated to the respective position coordinates corresponding to the four electrode pads in a state where the elliptical orbit is positioned.

  By performing the laser beam irradiation step on the four devices forming one group, the via holes are partially processed in the two devices of which the laser beam irradiation is the first time, and the via holes are already partially processed. In the other two devices that are executed and the laser beam is irradiated for the second time, the remaining unprocessed portion is subjected to via hole processing, whereby via hole processing is performed on all electrode pads of the other two devices. By completing the laser beam irradiation step, two devices that have completed the via hole processing corresponding to all the electrode pads are separated from the group, and two devices that are partially processed by the via hole are completed. Device and two raw devices adjacent in the processing feed direction Formed a flop, position the elliptic circular orbit into four devices in the new group, and the laser beam application step can be successively performed the elliptic circular path positioned step.

  In particular, by assigning numbers to a plurality of electrode pads arranged in each device in order, it is divided into an odd first electrode pad group and an even second electrode pad group. When setting the position information and performing the laser beam irradiation step on the four devices forming one group, the laser beam irradiation step includes the first electrode pad group of the four devices and the second Irradiate a pulsed laser beam while drawing an elliptical orbit to any one of the electrode pad groups that are not processed, thereby completing the via hole processing corresponding to all the electrode pads of the two devices. Separating the two devices for which the via holes have been completely processed for all the electrode pads from the group, and forming a first electrode pad group and a second electrode pad group A new group is formed by two devices with via holes processed in only one of them and two unprocessed devices adjacent to this in the processing feed direction, and four in the new group The elliptical trajectory is positioned in the device, the laser beam irradiation step and the elliptical trajectory positioning step are performed on the raw electrode pad group of the first and second electrode pad groups, It is preferable to complete the via hole processing for the device.

  In addition, when it is not possible to form a group by two devices and four devices adjacent to each other on the outer periphery of the wafer, a group is formed by less than four devices, and the irradiation of the laser beam to the region where the devices are missing Is preferred.

  Furthermore, in order to solve the above-mentioned main technical problems, according to the present invention, holding means for holding a wafer having a plurality of devices partitioned by predetermined dividing lines and formed on the surface in a plane defined by X and Y axes. A laser beam irradiating means for irradiating the wafer held by the holding means with a laser beam for processing, and formed on each device together with position information of each device on the wafer The position information storage means for storing the position information of the plurality of electrode pads, and the four electrodes disposed at the same position, with two devices adjacent to each other as one group. Elliptical trajectory generating means for generating an elliptical trajectory including a passing circle on the basis of positional information of the electrode pad, and positions corresponding to the four electrode pads to be processed The elliptical orbit positioning means for positioning the elliptical orbit, the laser beam irradiation means for irradiating the pulsed laser beam to the position corresponding to the four electrode pads while drawing the elliptical orbit, and relatively processing-feed the wafer and the pulsed laser beam However, a laser processing apparatus is provided which operates the laser beam application means and the elliptical orbit positioning means to form a via hole.

  The laser beam irradiation means includes an oscillator that oscillates a pulse laser beam at a repetition frequency M that is a multiple of 4, and a condenser that focuses the pulse laser beam oscillated by the oscillator onto a wafer held by the holding means, The elliptical trajectory generating means is disposed between the oscillator and the condenser, and an X-axis resonant scanner that oscillates a laser beam in the X-axis direction at a repetition frequency that is ¼ of the repetition frequency M, and a repetition frequency. The Y-axis resonant scanner which oscillates the laser beam in the Y-axis direction at a repetition frequency of 1⁄4 M, and the elliptical orbit for distributing the pulse laser beam to each electrode pad whose position information is stored in the position information storage means Generating an X-axis scan for moving the elliptical orbit generated by the elliptic orbit generating means in the X-axis direction; And a Y-axis scanner that moves the elliptical trajectory in the Y-axis direction. The elliptical trajectory passes through the four electrode pads to be processed based on the positional information of the electrode pad stored in the positional information storage means. Further, the sine curve generated by the X-axis resonant scanner is out of phase by π / 2 with respect to the sine curve generated by the Y-axis resonant scanner. It is preferable to do.

  According to the laser processing method of a wafer according to the present invention, position information storing step of storing position information of each device of a plurality of electrode pads formed on each device together with position information of each device on the wafer; Four adjacent devices as a group, an elliptical orbit generation step for generating an elliptical orbit including a circle passing through four electrode pads arranged at the same position in each device, and drawing the elliptical orbit A step of irradiating a laser beam to a position corresponding to the four electrode pads by a pulse laser beam irradiating means, and the elliptical trajectory so as to pass through a position corresponding to the four electrode pads to be processed next An elliptical orbit positioning step for positioning, and the wafer and the pulse laser beam irradiation means relative to each other; By performing via hole processing for forming a via hole by sequentially performing the laser beam irradiation step and the elliptical orbit positioning step while processing feeding, in forming one via hole, the maximum repetition frequency which does not cause a crack While maintaining at (for example, 10 kHz) or less, via-hole processing for irradiating a plurality of electrode pads with laser beams can be performed simultaneously, and productivity can be improved.

  In addition, by performing the laser beam irradiation step on the four devices forming one group, the via holes are partially processed in the two devices whose laser beam irradiation is the first time, and the via holes are already partially processed. In the other two devices in which the processing is performed and the laser beam is irradiated for the second time, via holes are processed on the remaining unprocessed portions, whereby via holes for all electrode pads of the other two devices are formed. The processing is completed, and by performing the laser beam irradiation step, two devices that have completed the via hole processing corresponding to all the electrode pads are separated from the group, and the via hole processing is partially performed 2 New devices with two devices and two raw devices adjacent in the processing feed direction Forming a group, positioning the elliptical trajectory on the four devices included in the new group, and sequentially performing the laser beam irradiation step and the elliptical trajectory positioning step, thereby providing a relative relationship between the wafer and the laser beam irradiation unit; Even when the elliptical trajectory passing through the position coordinates of the electrode pad to be processed next is positioned following the specific processing feed rate to deflect the irradiation direction of the laser beam, the deflection adjustment angle can be reduced, Appropriate processing can be performed by keeping the incident angle of the laser beam on the wafer within an allowable range.

  Further, according to the laser processing apparatus according to the present invention, holding means for holding a wafer having a plurality of devices partitioned by dividing lines and formed on the surface in a plane defined by the X axis and Y axis; A laser beam irradiating unit configured to irradiate a held wafer with a laser beam to perform processing, the position information of each device on the wafer, and a plurality of electrode pads formed on each device And an ellipse including a circle passing through four electrode pads arranged at the same position, with two devices and four adjacent devices as one group. Elliptical trajectory generation means for generating a trajectory based on the position information of the electrode pad, and the elliptical trajectory at a position corresponding to the four electrode pads to be processed Elliptical orbit positioning means for applying the laser beam, laser beam irradiating means for irradiating the pulsed laser beam to the positions corresponding to the four electrode pads while drawing the elliptical orbit, the laser beam irradiation while relatively feeding the wafer and the pulsed laser beam Since the via holes are formed by operating the means and the elliptical track positioning means, as described above, when laser beams are irradiated a plurality of times to one place to form the via holes, no crack is generated in the formation of the via holes. The via hole processing for irradiating a plurality of positions on which the electrode pads are formed with laser beams can be simultaneously performed while maintaining the repetition frequency below, and productivity can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS The perspective view of the laser processing apparatus which enforces the processing method of the to-be-processed object by this invention. FIG. 2 is a block diagram for explaining laser beam irradiation means, elliptical trajectory generation means, and elliptical trajectory positioning means provided in the laser processing apparatus shown in FIG. 1; FIG. 2 is a block diagram of control means provided in the laser processing apparatus shown in FIG. 1; The top view of the semiconductor wafer processed with the laser processing apparatus shown in FIG. 1, and one part enlarged view. Explanatory drawing which shows the via-hole process by 1st embodiment performed by this invention. Explanatory drawing which shows the action | operation of the elliptical track | orbit production | generation means shown in FIG. Explanatory drawing which shows the via-hole process of 2nd embodiment performed by this invention. Explanatory drawing which shows the via-hole process of 2nd embodiment performed by this invention.

  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a first preferred embodiment of a processing method according to the present invention and a processing apparatus for carrying out the processing method will be described in detail with reference to the attached drawings.

  FIG. 1 shows a perspective view of a laser processing apparatus 1 for carrying out the method of processing a wafer according to the present invention. The laser processing apparatus 1 comprises a stationary base 2 and arrows on the stationary base 2. A chuck table mechanism 3 that is disposed so as to be movable in the X-axis direction indicated by X and holds a workpiece, and a laser beam irradiation unit 4 that is disposed on the stationary base 2 are provided. The chuck table mechanism 3 is disposed on the stationary base 2 so as to be movable in the X-axis direction on the pair of guide rails 31 arranged in parallel along the X-axis direction, and the guide rails 31. A second sliding block 33 movably disposed on the first sliding block 32 in a Y-axis direction indicated by an arrow Y orthogonal to the X-axis direction; A cover table 35 supported by a cylindrical member 34 on a sliding block 33 of the second embodiment, and a chuck table 36 as holding means for holding a workpiece are provided. The chuck table 36 includes a suction chuck 361 formed of a porous material having air permeability, and holds a workpiece by operating suction means (not shown) on a holding surface which is the upper surface of the suction chuck 361. It is supposed to be. The chuck table 36 configured in this way is rotated by a pulse motor (not shown) disposed in the cylindrical member 34. The chuck table 36 is provided with a clamp 362 for fixing an annular frame that supports the workpiece via a protective tape.

  The first slide block 32 is provided with a pair of guided grooves 321, 321 fitted to the pair of guide rails 31, 31 on the lower surface, and formed in parallel along the Y-axis direction on the upper surface A pair of guide rails 322, 322 are provided. The first slide block 32 configured in this manner moves in the X-axis direction along the pair of guide rails 31, 31 by the guided grooves 321, 321 being fitted to the pair of guide rails 31, 31. Configured to be possible. The illustrated chuck table mechanism 3 includes X-axis direction moving means 37 for moving the first sliding block 32 along the pair of guide rails 31, 31 in the X-axis direction. The X-axis direction moving means 37 has a male screw rod 371 disposed in parallel between the pair of guide rails 31 and 31 and an output shaft of a pulse motor 372 for rotationally driving the male screw rod 371. It is done. The male screw rod 371 is screwed into a through female screw hole formed in a male screw block (not shown) provided on the lower surface of the central portion of the first sliding block 32 so as to protrude. Therefore, the first slide block 32 is moved in the X-axis direction along the guide rails 31 by driving the externally threaded rod 371 forward and reverse by the pulse motor 372.

  The illustrated laser processing apparatus 1 includes an X-axis direction position detection unit (not shown) for detecting the position of the chuck table 36 in the X-axis direction. The X-axis direction position detecting means moves along the linear scale along with the linear scale (not shown) arranged along the guide rail 31 and the first sliding block 32 arranged along the linear scale. The reading head is not shown. The reading head of the X-axis direction position detecting means sends a pulse signal of 1 pulse to the control means described later, for example, every 1 μm. And the control means mentioned later detects the X-axis direction position of the chuck table 36 by counting the input pulse signal. When the pulse motor 372 is used as the drive source for the X-axis direction moving means 37, the drive pulse of the control means, which will be described later, that outputs a drive signal to the pulse motor 372 is counted. The position in the axial direction can also be detected. When a servomotor is used as a drive source of the X-axis direction moving means 37, a pulse signal output from a rotary encoder for detecting the number of rotations of the servomotor is sent to the control means described later, and the control means inputs By counting the pulse signals, the position in the X-axis direction of the chuck table 36 can also be detected, and in the present invention, the type of means for detecting the position in the X-axis direction is not particularly limited.

  The second sliding block 33 is provided with a pair of guided grooves 331 and 331 which are fitted to a pair of guide rails 322 and 322 provided on the upper surface of the first sliding block 32 on the lower surface. By fitting the guided grooves 331, 331 to the pair of guide rails 322, 322, the guide grooves can be moved in the Y-axis direction. The illustrated chuck table mechanism 3 includes Y-axis direction moving means 38 for moving the second slide block 33 in the Y-axis direction along a pair of guide rails 322 and 322 provided on the first slide block 32. It is equipped. The Y-axis direction moving means 38 includes a male screw rod 381 disposed in parallel between the pair of guide rails 322 and 322, and a drive source such as a pulse motor 382 for rotationally driving the male screw rod 381. There is. The male screw rod 381 is rotatably supported at one end on a bearing block 383 fixed to the upper surface of the first slide block 32, and the other end is connected by transmission to the output shaft of the pulse motor 382. The male screw rod 381 is screwed into a penetrating female screw hole formed in a male screw block (not shown) provided on the lower surface of the center portion of the second sliding block 33. Therefore, by driving the externally threaded rod 381 forward and reverse by the pulse motor 382, the second sliding block 33 is moved along the guide rails 322, 322 in the Y-axis direction.

  The illustrated laser processing apparatus 1 is provided with Y axis direction position detection means (not shown) for detecting the position of the second sliding block 33 in the Y axis direction. The Y-axis direction position detecting means is arranged on the linear scale (not shown) arranged along the guide rail 322 and the second sliding block 33, as in the above-described X-axis direction position detecting means. It comprises a reading head (not shown) that moves along the linear scale together with the sliding block 33. The reading head of the Y-axis direction position detecting means sends a pulse signal of 1 pulse to the control means described later, for example, every 1 μm. And the control means mentioned later detects the Y-axis direction position of the 2nd sliding block 33 by counting the input pulse signal. When the pulse motor 382 is used as a drive source of the Y-axis direction moving means 38, the second sliding block is counted by counting the drive pulses of the control means described later that outputs a drive signal to the pulse motor 382. It is also possible to detect the position of 33 in the Y-axis direction. When a servomotor is used as a drive source of the Y-axis direction moving means 38, a pulse signal output from a rotary encoder for detecting the number of revolutions of the servomotor is sent to the control means described later, and the control means inputs By counting the pulse signal, the position of the second sliding block 33 in the Y-axis direction can also be detected.

  The laser beam irradiation unit 4 includes a support member 41 disposed on the stationary base 2, a casing 42 supported by the support member 41 and extending substantially horizontally, and a laser beam irradiation disposed in the casing 42. Means 5 and an imaging means 6 disposed at the front end of the casing 42 for detecting a processing area to be laser-processed are provided. The imaging unit 6 includes, in addition to a normal imaging device (CCD) that captures an image with visible light, an infrared illumination unit that irradiates a workpiece with infrared rays, an optical system that captures infrared rays emitted by the infrared illumination unit, An image sensor (infrared CCD) that outputs an electrical signal corresponding to the infrared rays captured by the optical system is used, and the captured image signal is sent to a control means to be described later.

  The laser beam application means 5 and the elliptical trajectory generation means 7 and the elliptical trajectory positioning means 8 provided in association with the laser beam application means 5 will be described with reference to FIG. The illustrated laser beam application means 5 comprises a pulse laser beam oscillator 51 for emitting a laser beam at a repetition frequency M (for example, 40 kHz), and an output adjustment means (attenuator) 52 for adjusting the output of the pulse laser beam oscillated from the pulse laser beam oscillator 51. Then, the irradiated laser beam is condensed and irradiated onto the direction changing mirror 53 for changing the direction of the pulsed laser beam toward the workpiece on the chuck table 36 and the semiconductor wafer 20 held on the chuck table 36. A condensing lens 54 is included. In the chuck table 36 shown in FIG. 2, the direction perpendicular to the plane on which the drawing is written is the X-axis direction, and the lateral direction is the Y-axis direction.

  As shown in FIG. 2, the elliptical trajectory generating means 7 is arranged between the pulse laser beam oscillator 51 and the condenser lens 54 and stores the position information of the electrode pads stored in the control means 9 described later. On the basis of this, the trajectory of the irradiation direction of the pulsed laser beam oscillated from the pulsed laser beam oscillator 51 is an elliptical orbit passing through four electrode pads disposed at the same position as viewed from the back of the four grouped devices. In the present invention, a circular orbit in which the minor axis of the ellipse coincides with the major axis is naturally included). For example, the repetition frequency M of the laser beam oscillated by the laser beam oscillating means is ¼. A Y-axis resonant scanner 71 that oscillates the irradiation direction of the laser beam in the Y-axis direction at a frequency of 10 kHz (for example, 10 kHz), and a frequency that is 1/4 of the repetition frequency M (for example, And a X-axis resonant scanner 72 to swing the irradiation direction of the laser beam in the X-axis direction at 10 kHz).

  The elliptical orbit positioning means 8 is such that the trajectory of the irradiation direction of the pulse laser beam forming the elliptical orbit passing through the elliptical orbit generation means 7 always passes position coordinates corresponding to the four electrode pads to be processed on the wafer. The X-axis scanner (acousto-optical element (AOD)) 81 for adjusting the elliptical orbit by adjusting the position of the elliptical orbit, for example, in the X-axis direction, and the elliptical orbit generated by the A damper comprising a Y-axis scanner (acousto-optical element (AOD)) 82 for deflecting and adjusting an elliptical orbit in the Y-axis direction, and further absorbing a laser beam used when selectively stopping the irradiation of the laser beam It has 83. The acousto-optic device (AOD) constituting the X-axis scanner 81 and the Y-axis scanner 82 has a deflection angle of a laser beam passing through the acousto-optic device (AOD) according to a voltage applied from the control means 9 described later. The elliptical orbit in the laser beam irradiation direction generated by the elliptical orbit generating means can be deflected in the X axis direction by the action of the X axis scanner 81. Similarly, Y By the action of the axis scanner 82, the elliptical orbit in the laser beam irradiation direction can be deflected in the Y-axis direction.

  The elliptical trajectory generation means 7 and the elliptical trajectory positioning means 8 are not limited to the above specific configurations, and may be replaced with other known means as long as they have similar functions. For example, each acousto-optical element (AOD) can be changed to a piezo scanner or galvano scanner capable of exhibiting the same deflection function. The reflection mirror 53 can also be configured as a scanning mirror 53 ′ that further adjusts and corrects the irradiation direction of the pulse laser beam that has passed through the elliptical orbit positioning means 8.

  The illustrated laser processing apparatus 1 includes control means 9 shown in FIG. The control means 9 is constituted by a computer, and a central processing unit (CPU) 91 that performs arithmetic processing according to the control program, a read only memory (ROM) 92 that stores the control program, etc., and read / write that stores operation results etc. A random access memory (RAM) 93, an input interface 94, and an output interface 95.

  FIG. 4 is a plan view (bottom) of a semiconductor wafer 20 as a workpiece to be processed by the method for processing a via hole according to the present invention, and four devices 22 adjacent to each other with two parts enlarged in part. The figure to show (upper stage) is shown. As shown in the drawing, the semiconductor wafer 20 supported on the annular frame F via the protective tape T has a plurality of substrates arranged in a lattice pattern on the surface of the substrate formed of silicon having a thickness of 100 μm whose back side is ground. A plurality of areas are divided by the streets 21. Devices 22 such as IC and LSI are respectively formed in the divided areas, and the surface side on which the devices 22 are formed is adhered to the protective tape T. Each device 22 has the same configuration. A plurality of electrode pads P1 to P20 are formed on the surface of each device 22, respectively. The electrode pads P1 to P20 are made of a metal material such as aluminum, copper, gold, platinum, nickel or the like, and have a thickness of 1 to 5 μm.

  The semiconductor wafer 20 is provided with via holes reaching the respective electrode pads by irradiating a pulse laser beam from the back side of the substrate based on the processing method of the present invention. In order to form via holes in the semiconductor wafer 20, A laser processing apparatus 1 shown in FIG. 1 is used. The formation of the via holes is not limited to the irradiation of the laser beam from the back surface, but can be performed from the surface, that is, the side on which the device is formed, and is not limited to this embodiment. As described above, the laser processing apparatus 1 shown in FIG. 1 includes the chuck table 36 for holding the workpiece and the laser beam application means 5 for irradiating the workpiece held on the chuck table 36 with the laser beam. The chuck table 36 is configured to suck and hold the workpiece, and the workpiece is moved in the machining feed direction indicated by the arrow X in FIG. While being moved, it is moved in the index feed direction indicated by the arrow Y by the index feed mechanism constituted by the Y-axis direction moving means 38.

Hereinafter, a via hole processing method for forming a via hole reaching the electrode pad of the device 22 formed in the semiconductor wafer 20 shown in FIG. 4 using the laser processing apparatus 1 shown in FIG. 1 will be described.
First, the surface side of the semiconductor wafer 20 is placed on the chuck table 36 of the laser processing apparatus 1 shown in FIG. 1, and the semiconductor wafer 20 is sucked and held on the chuck table 36. Therefore, the semiconductor wafer 20 is held so that the back side is on the upper side.

  As described above, the chuck table 36 holding the semiconductor wafer 20 by suction is positioned directly below the imaging means 6 by the processing and feeding mechanism. When the chuck table 36 is positioned directly below the imaging means 6, in this state, the grid-like streets 21 formed on the semiconductor wafer 20 held by the chuck table 36 are in the X-axis direction and the Y-axis direction. The semiconductor wafer 20 held on the chuck table 36 is imaged by the imaging means 6 so as to be disposed at a predetermined position, and image processing such as pattern matching is performed to perform alignment work. At this time, the surface of the substrate on which the streets 21 of the semiconductor wafer 20 are formed is positioned on the lower side. However, as described above, the image pickup means 6 is an infrared illumination means, an optical system that captures infrared rays, and an electric power corresponding to infrared rays. Since it is configured by an imaging element (infrared CCD) or the like that outputs a signal, it is possible to image the street 21 on which the planned dividing line is to be formed by watermarking from the back side of the substrate.

By carrying out the alignment operation described above, the semiconductor wafer 20 held on the chuck table 36 is positioned at a predetermined coordinate position on the chuck table 36. Here, in the processing method according to the present invention, all the electrode pads P ₁ formed on each device 22 together with the positional information on all the devices 22 formed on the surface of the substrate of the semiconductor wafer 20 on the semiconductor wafer 20. A position information storage step for storing position information on each of the devices 22 to ₂₀ is executed, and stored in a random access memory (RAM) of the control means 9 of the laser processing apparatus 1.

The position information storage step will be described in more detail. As shown in the lower part of FIG. 4, in the present embodiment, each device 22 formed on the semiconductor wafer 20 is provided with position information for specifying the position on the semiconductor wafer 20, and The direction is the X-axis, the vertical direction is the Y-axis, the leftmost device is directed to the right, X ₁ , X ₂ , X _3. Y ₁ , Y ₂ , Y ₃ ..., Y n are defined. Therefore, the position coordinates of each device 22 shown enlarged a part of the upper part, the upper left of the device 22 _{(X 1, Y 4),} the upper right of the device 22 _{(X 2, Y 4),} lower right The device 22 is defined as (X ₂ , Y ₅ ), and the lower left device 22 is defined as (X ₁ , Y ₅ ).

Furthermore, in each device 22 of the present embodiment, a first electrode pad row arranged in a direction (Y-axis direction) orthogonal to the machining feed direction (X-axis direction) while being placed on the chuck table 36. L1, is formed the second electrode pad rows L2, position information for indicating a position in each device 22 of the electrode pads P ₁ to P ₂₀ are defined. More specifically, when viewed from the upper left device 22 (X ₁ , Y ₄ ) in FIG. 4, for example, the X coordinates of the electrode pads P _{1 to} P ₁₀ constituting the first electrode pad row L 1 on the left side are shown. x ₁ , the X coordinate of the electrode pads P _{11 to} P ₂₀ constituting the second electrode pad row L 2 on the right side is defined as x _2, and the first electrode pad row L 1 and the second electrode pad row L 2 are constituted. Y coordinates of the electrode pads _P 1 _{to P 20} is defined as _{y 1, y 2, y 3} ··· y 10 toward the uppermost downwards. That is, the electrode pads P _{1 to} P ₁₀ arranged from above the first electrode pad row L1 on the left side of the device 22 (X ₁ , Y ₄ ) in the enlarged view shown in the upper part of FIG. The position information is defined as (x ₁ , y ₁ ), (x ₁ , y ₂ ), (x ₁ , y ₃ )... (X ₁ , y ₁₀ ), respectively, and the second electrode pad row on the right side The positional information of the electrode pads P _{11 to} P ₂₀ arranged from the top to the bottom of L2 is (x ₂ , y ₁ ), (x ₂ , y ₂ ), (x ₂ , y ₃ ), respectively. It is defined as (x ₂ , y ₁₀ ). Then, the position information is given to the electrode pads P _{1 to} P _{20 of} all the devices 22 by the same definition as this. Thereby, for example, the four devices 22 (X ₁ , Y ₄ ), (X ₂ , Y ₄ ), (X ₂ , Y ₅ ), (X ₁ , Y ₅ ) shown in the upper part of FIG. All the positional information of the uppermost electrode pad P1 of _one electrode pad row L1 is (x ₁ , y ₁ ). Therefore, the electrode pads P ₁ in the upper left of the four devices shown will be referred to as "electrode pads of the same position".

  As described above, in the processing method according to the present invention, all the electrodes formed in each device 22 together with the above-mentioned positional information on the semiconductor wafer 20 of all the devices 22 formed on the surface of the substrate of the semiconductor wafer 20 A position information storing step for storing the position information on each device 22 of the pad is executed. Then, since the semiconductor wafer 20 held on the chuck table 36 is positioned at a predetermined coordinate position on the chuck table 36 by the alignment operation, all the semiconductor wafers 20 necessary for the irradiation of the laser beam are The coordinate position of the electrode pad on the chuck table is automatically identified.

As described above, when the alignment is performed and the position information storage step is performed, the elliptical trajectory generation step is performed by the elliptical trajectory generation means. For the purpose of clearly explaining the elliptical trajectory generation step, the four devices 22 (X ₁ , Y ₄ ), (X ₂ , Y ₄ ), (X ₂ , Y ₅ ), (X ₁ ) shown in the upper part of FIG. , Y ₅ ) will be described as an example of the case where the laser processing is performed.

In the processing method of the present invention, four devices 22 in two rows and two rows adjacent to each other are grouped into one group, and laser processing is simultaneously performed on the four devices 22. First, the processing feed means (X-axis direction moving means 37) of the chuck table 36 holding the semiconductor wafer 20 and the indexing feed means (Y-axis direction moving means 38) are operated to for rocking operation, in the absence deflection action of the elliptical orbit locating means 8, if such laser from laser oscillator 51 is in the position indicated by the point O ₁ in FIGS. 5 (a) the laser beam is irradiated when oscillated The chuck table 36 is moved. This point O ₁ is first subjected to via hole processing in each device 22 (X ₁ , Y ₄ ), (X ₂ , Y ₄ ), (X ₂ , Y ₅ ), (X ₁ , Y ₅ ). Of the four electrode pads P ₁ (x ₁ , y ₁ ) disposed at the same position on each of the devices 22.

If the point O ₁ is positioned directly below the laser beam irradiation means 5, the elliptical trajectory generating means 7, based on the position information of the stored four electrode pads P1, the irradiation direction of the laser beam applied from the laser oscillator 51 There generating an elliptical orbit an elliptical orbit through the four electrode pads P _1. More specifically, by oscillating the scanning mirror 711 of the Y-axis resonant scanner 71 at 10 kHz, the irradiation direction of the laser beam is reciprocated in the Y-axis direction (see FIG. 6A) and the X-axis resonant scanner The scanning direction of the laser beam is reciprocated in the X-axis direction by swinging the 72 scanning mirrors 721 at the same frequency of 10 kHz as that of the Y-axis resonant scanner 71 (see FIG. 6B). Here, as shown in FIG. 6, the sine curve drawn by the swinging of the X-axis resonant scanner 721 is π / with respect to the sine curve drawn by the swinging of the scanning mirror 711 of the Y-axis resonant scanner 71. The oscillation direction of the laser beam emitted from the laser beam oscillator 51 passes through the four electrode pads P1 (x1, y1) which are oscillated so as to be delayed by two phases and which have the same position coordinates on each device 22 The amplitude of the oscillation by the scanning mirror 711 of the Y-axis resonant scanner 71 and the scanning mirror 721 of the X-axis resonant scanner 72 is set.

When the irradiation direction of the pulse laser beam is irradiated elliptical orbit so as to pass through the four electrode pads P ₁ is generated, the timing of the pulsed laser beam passes through the coordinate position on the chuck table 36 of the four electrode pads P ₁ Then, the pulse laser beam irradiation means 5 irradiates the pulse laser beam (pulse laser beam irradiation step). More specifically, the repetition frequency of the pulse laser beam oscillated from the laser beam oscillator 51 is set to 40 kHz, which is four times the oscillation frequency of the scanning mirror of the X-axis and Y-axis resonant scanner, 10 kHz, and the Y-axis resonant scanner The irradiation timing of the pulsed laser beam is adjusted so that the laser beam is oscillated at the timing at which the phase is π / 4, 3π / 4, 5π / 4, and 7π / 4 with respect to the oscillation period, and the electrode pad P ₁ The back surface of the semiconductor wafer 20 is repeatedly irradiated with a plurality of pulse laser beams in accordance with the position coordinates of {circle over (1)}, and the via holes are formed. When forming the via holes as described in the processing conditions to be described later, the via holes reaching the electrode pads formed from the back surface to the front surface side of the semiconductor wafer 20 are formed by irradiating the pulse laser beam a total of 10 times per position. It is supposed to be. In the present embodiment, the place where the via hole is completed is indicated by a black circle, and the unprocessed point is indicated by an open circle.

Each processing condition in the via hole processing is set as follows.
[Wafer conditions]
Street distance: 5 mm in the X-axis direction, 7 mm in the Y-axis direction
Electrode pad: 10 in the Y-axis direction, 2 rows = 20 in the X-axis direction Via hole formation: Pulse laser 10 times / electrode pad

[Laser processing equipment conditions]
Laser beam wavelength: 355 nm
Average output: 4W
Repetition frequency: 40 kHz
Spot diameter: φ10μm
Processing feed rate: 500 mm / sec

When the via hole processing is performed based on the above conditions, the irradiation direction of the pulsed laser beam draws an elliptical orbit at a frequency of 10 kHz. The pulsed laser beam is oscillated four times, and the pulsed laser beam is emitted at a frequency of 10 kHz to _one electrode pad P1. In other words, the electrode pads P ₁ of 4 locations are substantially so that the via hole is performed at a frequency of substantially 10kHz simultaneously.

The first four devices of the electrode pad P ₁ to pulse laser beam a predetermined plurality of times (in the condition 10 times) by irradiating only after the formation of the via hole for the four electrode pads P ₁ is completed, elliptical orbit positioning means by applying a 8 predetermined voltage to the acousto-optic device (AOD) of the Y-axis scanner 82, by adjusting the deflection angle of the pulsed laser beam with respect to the Y-axis direction, the center O ₁ of the elliptical orbit, O ₂ Move to (See Fig. 5 (b)) and perform the elliptical orbit positioning step so that the irradiation direction of the pulse laser beam passes through the four electrode pads P ₂ (x ₁ , y ₂ ) to be processed next is, then, as with the electrode pad P _1, the pulsed laser beam irradiation step is carried out for the four electrode pads P _2.

In this way, the pulsed laser beam irradiation step, sequentially executes the elliptical orbit positioning step, after the via hole with respect to the electrode pads P ₁ to P ₁₀ of the first electrode pad row L1 is completed, as shown in FIG. 5 (c) The center of the elliptical trajectory is moved to O _20, and the irradiation direction of the pulse laser beam passes through the four electrode pads P ₂₀ (x ₂ , y ₁₀ ) of the second electrode pad row L 2 to be processed next. The elliptical trajectory positioning step is performed as follows. Then, when the via hole processing for the four electrode pads P ₂₀ (x ₂ , y ₁₀ ) is completed by executing the above-described pulse laser beam irradiation step, the acousto-optic element of the Y axis scanner 82 of the elliptical orbit positioning means 8 (AOD) by applying a predetermined voltage to, by adjusting the deflection angle of the pulsed laser beam with respect to the Y-axis direction, and the elliptical orbit positioning step of moving the elliptical orbit the electrode pad P ₁₁ direction (upward in the drawing) sequentially executes a pulse laser beam irradiation step, via holes for by the center of the elliptical orbit is positioned O ₁₁ as shown in FIG. 5 (d) all of the electrode pads P ₁₁ to P ₂₀ of the electrode pad rows L2 To complete. With the above, for all the electrode pads P _{1 to} P _{20 in the} four devices 22 (X ₁ , Y ₄ ), (X ₂ , Y ₄ ), (X ₂ , Y ₅ ), (X ₁ , Y ₅ ) Via hole processing is completed. Even during the execution of the elliptical orbit positioning step and the pulse laser beam irradiation step, the machining feed by the X-axis direction moving means 37 is continuously performed at the machining feed speed. The X-axis scanner 81 adjusts the deflection angle in the X-axis direction to correspond to the relative positional change between the semiconductor wafer 20 and the pulsed laser beam application means 5, and the irradiation direction of the pulsed laser beam is always processed on each device. It is positioned so as to follow on the four electrode pads to be targeted.

All the electrode pads P of the four devices 22 (X ₁ , Y ₄ ), (X ₂ , Y ₄ ), (X ₂ , Y ₅ ), (X ₁ , Y ₅ ) by the action of the processing feed means. ₁ When the via hole is completed timing for to P _20, the processing-feed direction of the raw adjacent four devices _{22 (X 3, Y 4)} , (X 4, Y 4), (X 3, Y 5) , (X ₃ , Y ₅ ) to the processed four devices 22 (X ₁ , Y ₄ ), (X ₂ , Y ₄ ), (X ₂ , Y ₅ ), (X ₁ , Y ₅ ) It has moved to the position where the via hole processing was started. Therefore, a new group is set with the four unprocessed devices 22 (X ₃ , Y ₄ ), (X ₄ , Y ₄ ), (X ₃ , Y ₅ ), (X ₄ , Y ₅ ), and an ellipse is set. By applying a predetermined voltage to the X-axis scanner 81 and Y-axis scanner 82 of the orbit positioning means 8, the irradiation direction of the laser beam forming the elliptical orbit is adjusted by deflection, and the first of each unprocessed device 22 is The four unprocessed via holes that are adjusted so as to pass through the electrode pads P ₁ (x ₁ , y ₁ ) disposed at the same position in the electrode pad row and set as a new group with the same via hole processing as described above. The process is performed on the device 22 to complete via hole processing for all the electrode pads P _{1 to} P _{20 of} the new four devices 22. Then, by repeating such processing, the via hole processing is completed for all the devices 22 disposed in the processing feed direction.

Once all the devices 22 arranged in the processing feed direction have been processed, the chuck table 36 is moved in the indexing feed direction by the Y-axis direction moving means 38 to make the laser beam application means 5 unprocessed. In the position where 22 is disposed, the via hole processing similar to the above is sequentially performed on the new row. By repeating this, via hole processing is completed at positions corresponding to the electrode pads P _{1 to} P ₂₀ on all the devices 22 arranged on the semiconductor wafer 20.

In addition, like the area | region shown by H in the top view of the semiconductor wafer 20 of FIG. 4, on the relationship which arrange | positions the device 22 on the circular-shaped semiconductor wafer 20 efficiently, two devices mutually adjacent and four devices are shown. Sometimes it can not be formed as one group. In such a case, for example, a group is formed by three devices 22 (X ₄ , Y ₁ ), (X ₃ , Y ₂ ), and (X ₄ , Y ₂ ) in the region indicated by H. Then, laser processing is performed according to the same procedure as the via hole processing performed on the four devices 22 described above, but the region adjacent to the devices 22 (X ₄ , Y ₁ ) and (X ₃ , Y ₂ ), that is, The damper 83 absorbs the laser beam by the action of the Y-axis scanner 82 at the timing when the pulsed laser beam is irradiated to the area where the device is missing so that the pulse laser beam is not irradiated to the area where the device is missing. The laser beam is deflected and adjusted, and the irradiation of the laser beam toward the condenser 54 is stopped. By doing this, it becomes possible to carry out the procedure for carrying out the via hole processing on the four devices substantially as it is.

  Furthermore, when the number of devices 22 arranged in the processing feed direction on the semiconductor wafer 20 is not even, four devices can not form a group at the beginning or end of the processing feed direction, 2 It is assumed that one device must form a group. In this case, with respect to the region where the device is missing by the same means as described above, the laser beam irradiation direction is adjusted toward the damper 83 each time, and the laser beam irradiation from the condenser 54 is stopped. By doing so, it becomes possible to carry out via hole processing substantially similar to the case where the above four devices form a group, even for a group formed by two devices.

  Since the above-described first embodiment of the present invention is configured as described above, in the formation of one via hole, while maintaining the maximum repetition frequency (for example, 10 kHz) that does not cause cracks, It is possible to simultaneously carry out via hole processing of irradiating a laser beam to a position corresponding to the electrode pad, and productivity can be improved. In this embodiment, the repetition frequency by the laser beam oscillator 51 is set to 40 kHz, and the oscillation frequency in the X-axis direction and Y-axis direction in the elliptical orbit generation means is set to 10 kHz, but the present invention is not limited to this. If the repetition frequency M of the pulse laser beam oscillated from the laser beam oscillator 51 is a multiple of 4, and the oscillation frequency is made 1/4 of the repetition frequency M by the elliptical orbit generation means, the same as in the present embodiment. It is possible to implement control that exhibits the effects.

  Below, 2nd embodiment by this invention is described. In the second embodiment, the same laser processing apparatus 1 as in the first embodiment can be used, and only the procedure of via hole processing based on the laser beam irradiation means 5 and the elliptical orbit positioning means 8 is different. Only the different points will be described, and the description of the remaining points that are the same will be omitted.

  As in the first embodiment, the laser beam irradiation step in the second embodiment is a laser beam that sequentially irradiates pulse laser beams while drawing an elliptical orbit with respect to the electrode pads at the same positions of the four devices 22 included in the same group. This is common in that the irradiation step is performed. However, in the present embodiment, by performing the laser beam irradiation step on the four devices constituting one group, via holes are partially processed in the two devices where the laser beam irradiation is performed for the first time, In the other two devices that have already been partially subjected to via-hole processing and the laser beam is irradiated for the second time, all the other two devices are formed by applying via-hole processing to the remaining unprocessed portion. The via hole processing is completed for the electrode pads of the two, and by performing the laser beam irradiation step, two devices that have completed the via hole processing corresponding to all the electrode pads are separated from the group and partially processed by the via hole processing. Two devices being machined, and two unprocessed ones adjacent in the machining feed direction A first group is formed in that a new group is formed with the devices, the elliptical trajectory is positioned on the four devices included in the new group, and the laser beam irradiation step and the elliptical trajectory positioning step are sequentially performed. It is different from the form.

  In the second embodiment, the laser beam irradiation step and the elliptical orbit positioning step are processed to form a via hole for each device 22 disposed in the enlarged region in the upper part of FIG. 4 as in the first embodiment. A more specific explanation will be given by taking the case of applying as an example. In the present embodiment, the first electrode pad group, which is an odd number, and the second electrode pad, which is an even number, are assigned by sequentially assigning numbers to a plurality of electrode pads disposed in each device. When the position information is divided into groups and the laser beam irradiation step is performed on the four devices forming one group, the laser beam irradiation step includes the first electrode pad group of the four devices. The pulse laser beam is irradiated while drawing an elliptical orbit to one of the unprocessed electrode pads among the second and the second electrode pads, thereby corresponding to all the electrode pads of the two devices. After completion of the via hole processing, the two devices for which the via hole processing has been completed for all the electrode pads are separated from the group, and the first electrode pad group, A new group is formed by two devices in which via holes are processed in only one of the electrode pads in this group and two unprocessed devices adjacent to this in the processing feed direction, to form a new group. The elliptical trajectory is positioned in the four devices included, and the laser beam irradiation step and the elliptical trajectory positioning step are performed on the raw electrode pad group among the first and second electrode pad groups. , And complete the via hole processing for two devices in sequence.

As illustrated in FIG. 7A, in the second embodiment, first, four devices 22 (X ₁ , Y ₄ ), (X ₂ , Y ₄ ), (X ₂ , Y ₅ ), ( A group is not formed by X ₁ and Y ₅ ), but is formed by two devices 22 (X ₁ , Y ₄ ) and (X ₁ , Y ₅ ). In other words, a group is formed on the left side of the device 22 (X ₁ , Y ₄ ), (X ₁ , Y ₅ ) as if virtual devices 22 ′ and 22 ′ exist, and the device 22 (X ₁ , Y ₄ And the (X ₁ , Y ₅ ) electrode pads are positioned to partially form the first via hole processing for the devices 22 (X ₁ , Y ₄ ), (X ₁ , Y ₅ ). A via hole process is performed by irradiating a pulse laser beam. At the timing when the pulse laser beam is irradiated on the virtual devices 22 ′ and 22 ′, the laser beam irradiation from the condenser 54 is stopped using the Y-axis scanner 82 and the damper 83 described above.

Here, the application of the “partial” via hole processing will be described. First, numbers are sequentially assigned to a plurality of electrode pads disposed in each device 22 like P _{1 to} P ₂₀ as in the case shown in FIG. 4. Then, based on each number, odd-numbered electrode pads (P ₁ , P ₃ , P ₅ , P ₇ , P ₉ , P ₁₁ , P ₁₃ , P ₁₅ , P ₁₇ , P ₁₉ ) are put together as a first The electrode pads are grouped into even electrode pads (P ₂ , P ₄ , P ₆ , P ₈ , P ₁₀ , P ₁₂ , P ₁₄ , P ₁₆ , P ₁₈ , P ₂₀ ). Set as a group. Then, via holes are not formed in order for all of the electrode pads P _{1 to} P ₂₀ arranged in each device 22, but as shown in FIG. The via hole processing is sequentially performed on the electrode pads of the above, that is, only on the electrode pads of the first electrode pad group.

Thus, if via hole processing is performed only on the first electrode pad group of devices 22 (X ₁ , Y ₄ ) and (X ₁ , Y ₅ ), that is, “partially”, it is stored in control means 9. The control program separates the virtual devices 22 'and 22' from the group, and partially performs via hole processing on the devices 22 (X ₁ , Y ₄ ), (X ₁ , Y ₅ ), and the device 22 (X 1 New groups are formed by the unprocessed devices 22 (X ₂ , Y ₄ ), (X ₂ , Y ₅ ) adjacent in the processing feed directions of ( ₁ , Y ₄ ), (X ₁ , Y ₅ ). Then, the laser beam irradiation means 5 and the elliptical orbit positioning means 8 are actuated to further perform a laser beam irradiation step. Here, since the first electrode pad group including the odd-numbered electrode pads in the devices 22 (X ₁ , Y ₄ ) and (X ₁ , Y ₅ ) has already been subjected to the via hole processing, This time, via-hole processing is performed on the second electrode pad group including even-numbered electrode pads that are not processed in any of the four devices. When the processing is completed, as shown in FIG. 7-2 (b), all the electrodes of the devices 22 (X ₁ , Y ₄ ) and (X ₁ , Y ₅ ) for which the second via hole processing has been performed The via hole processing corresponding to the pads P _{1 to} P ₂₀ is completed. On the other hand, the devices 22 (X ₂ , Y ₄ ) and (X ₂ , Y ₅ ) newly added to the group are the first irradiation of the laser beam this time, and the second device composed of the even-numbered electrode pads The laser beam is irradiated only to the electrode pad group, and the via holes are only partially formed.

When the via hole processing is completed, the devices 22 (X ₁ , Y ₄ ) and (X ₁ , Y ₅ ) in which all the via hole processing is completed are separated from the group, and the via hole processing is performed only for the second electrode pad group. It made that it has a device _{22 (X 2, Y 4)} , (X 2, Y 5) and the machining feed direction of the raw adjacent two devices _{22 (X 3, Y 4)} , (X 3, Y 5 ) And a new group are formed, and via hole processing similar to the above is executed. That is, by the first via hole processing for the devices 22 (X ₂ , Y ₄ ) and (X ₂ , Y ₅ ), the via hole processing is already performed for the second electrode pad group configured with even-numbered electrode pads. Because of this, this time, the via hole processing is performed on the first electrode pad group constituted by the odd-numbered electrode pads. When the processing is completed, as shown in FIG. 7-2 (c), all the electrode pads of the devices 22 (X ₂ , Y ₄ ) and (X ₂ , Y ₅ ) that have become the second via hole processing processing corresponding to P ₁ to P ₂₀ is completed. Note that although it is possible to perform via hole processing on the devices 22 arranged in the process feed direction by sequentially repeating such processing, when completing via hole processing on the two devices 22 to be finally grouped, Since there are no adjacent raw devices, two devices 22 (X ₁ , Y ₄ ) and (X ₁ , Y ₅ ) to be processed first are assumed to be virtual devices 22 ′ and 22 ′. In the same manner as in the case where the processing is performed, the via holes are processed by forming a group so as to position the elliptical orbit on the assumption of the virtual devices 22 'and 22'. Thereby, it is possible to complete the via hole processing of all the devices 22 disposed in the processing feed direction.

  According to the second embodiment described above, in order to complete the via hole processing for two devices while performing the via hole processing for four devices, a comparison with the first embodiment for simultaneously completing the via hole processing for four devices However, the deflection angle for deflecting and adjusting the laser beam using the X-axis scanner 81 is small so as to follow the semiconductor wafer 20 processed and fed in the X-axis direction, and the incident angle of the laser beam with respect to the wafer is kept within an allowable range. Appropriate processing can be performed.

In the second embodiment described above, the via holes are divided into odd-numbered or even-numbered electrode pads as means for performing the "partially" via holes processing on the two devices whose laser beam irradiation is the first time. Although the process is performed, the means for performing the "partial" via hole process is not limited to this. For example, instead of performing the via hole processing on the odd-numbered electrode pads in the second embodiment, the via hole processing is performed on the electrode pads P _{1 to} P _{5 and} P _{11 to} P ₁₅ . If the via holes are processed to the remaining electrode pads P _{6 to} P ₁₀ and P _{16 to} P ₂₀ , the same function and effect can be obtained. In the second embodiment, an example in which 20 electrode pads are arranged in two rows such as L1 and L2 has been presented. However, the arrangement of the electrode pads is not limited to this. There may be a case where only one row of electrode pads is provided for the device, and various arrangements such as 10 in one row and 2 in the other row are envisaged. Even in the arrangement pattern, it is possible to partially process via holes by dividing the electrode pads into two groups as in the second embodiment.

  Furthermore, in the above laser processing conditions, when via hole processing is performed corresponding to one electrode pad, the output and the like are adjusted so that the via hole processing is completed by irradiating the pulse laser beam 10 times. In place of performing odd-numbered and even-numbered via-hole processing as in the embodiment, laser beam irradiation is sequentially performed five times on all electrode pads for the four devices constituting one group. It can be a process that only needs to be done. As a result, with respect to two devices that are to be irradiated with the first laser beam, only partial processing is performed on each electrode pad. Then, by irradiating the other two devices, which have already been irradiated with the laser beam five times, with the second laser beam, the via hole processing for all the electrode pads of the other two devices is completed. Thus, as in the second embodiment described above, it is possible to complete via hole processing for two devices sequentially, and it is possible to obtain the same effects as obtained in the second embodiment. There is no need to change the first and second laser beam irradiation methods, and the processing apparatus can be simplified. As described above, various modification examples can be adopted as means for “partially” performing the via hole processing.

In the above embodiment, the position information of each device in the wafer to be stored in the control unit, and the position information in each device of the plurality of electrode pads formed on the devices, "device _{22 (X 1, Y 4)} , (X ₁ , Y ₅ ) ”or“ P _{1 to} P ₁₀ (x ₁ , y ₁ ), (x ₁ , y ₂ ), (x ₁ , y ₃ )... (X ₁ , y ₁₀ However, the position information of each device and the format of the position information in each device of the plurality of electrode pads formed in each device are not limited to this. The position information of each device is for performing via hole processing while forming a group by the selected device on the wafer or separating the processed device, and the devices at any positions on the wafer Any form of information may be used as long as it can be used to distinguish which group is to be separated from which group. Also, the format of the position information in each device of the plurality of electrode pads formed in each device should be such that the position of the corresponding electrode pad in each device can be distinguished from the positions of other electrode pads. For example, any form can be adopted.

1: Laser processing apparatus 2: Stationary base 3: Chuck table mechanism 36: Chuck table 4: Laser beam irradiation unit 5: Laser beam irradiation means 52: Output adjustment means 53: Reflection mirror 54: Condenser 6: Imaging means 7: Ellipse Orbit generation means
71: Y-axis resonant scanner 72: X-axis resonant scanner 8: Elliptical orbit positioning means 81: X-axis scanner (acousto-optic device (AOD))
82: Y-axis scanner (acousto-optical element (AOD))
20: Semiconductor wafer 21: Planned dividing line 22: Device

Claims (8)

A method of processing a wafer in which a plurality of devices are defined by dividing lines and formed on a surface,
Storing positional information in each device of a plurality of electrode pads formed in each device together with positional information of each device in the wafer;
An elliptical trajectory generation step of generating an elliptical trajectory including a circle passing through four electrode pads arranged adjacent to each other in a group at four devices adjacent to each other;
A laser beam irradiation step of irradiating a pulse laser beam by a pulse laser beam irradiating means to a position corresponding to the four electrode pads while drawing the elliptical orbit;
An elliptical trajectory positioning step of positioning the elliptical trajectory so as to pass through the positions corresponding to the four electrode pads to be processed next;
A via hole for forming a via hole corresponding to the electrode pad in the wafer by sequentially performing the laser beam irradiation step and the elliptical orbit positioning step while relatively processing and feeding the wafer and the pulse laser beam irradiation means. A method of processing a wafer to be processed.   The laser beam irradiation step performs via-hole processing in which a plurality of pulse laser beams are irradiated to positions corresponding to the four electrode pads in a state where the elliptical orbit is positioned so as to pass through the four electrode pads. The method of processing a wafer according to 1. By performing the laser beam irradiation step on the four devices forming one group, the via holes are partially processed in the two devices of which the laser beam irradiation is the first time, and the via holes are already partially processed. In the other two devices that have been executed and the second irradiation of the laser beam, the remaining raw parts are subjected to the via hole processing so that the via holes are processed for all electrode pads of the other two devices. To complete,
By performing the laser beam irradiation step, the two devices for which the via hole processing has been completed corresponding to all the electrode pads are separated from the group, and the two devices for which the via hole processing is partially performed, and the processing feed direction Forming a new group with two raw devices adjacent to the second group, positioning the elliptical orbits to four devices included in the new group, and applying the laser beam irradiation step and the elliptical orbit positioning step The wafer processing method according to claim 1, which is sequentially performed. By sequentially assigning numbers to a plurality of electrode pads arranged in each device, the positions are divided into an odd-numbered first electrode pad group and an even-numbered second electrode pad group. Set the information,
The laser beam irradiation step draws a pulsed laser beam while drawing an elliptical trajectory with respect to one of the unprocessed electrode pads among the first electrode pad group and the second electrode pad group of the four devices. Irradiation is performed to complete the via holes corresponding to all the electrode pads of the two devices, and the two devices completed with the via holes for all the electrode pads are separated from the group, and the first electrode pad group A new group is formed with two devices in which via holes are processed in only one of the second electrode pad groups and two unprocessed devices adjacent to this in the processing feed direction. The elliptical orbits are positioned on four devices included in a group, and the first and second electrode pads are compared with the unprocessed electrode pads. And Heather beam irradiation step, performed the elliptic circular orbit positioning step, and to complete the via hole for the sequential two devices, the wafer processing method of claim 3.   2. When a group cannot be formed by two devices and four devices adjacent to each other on the outer periphery of the wafer, the group is formed by less than four devices, and irradiation of the laser beam to the region where the device is missing is stopped. 5. The wafer processing method according to any one of 1 to 4. Holding means for holding a plurality of devices divided by a planned dividing line and having a wafer formed on the surface in a plane defined by the X axis and Y axis, and processing the wafer by irradiating the wafer held by the holding means with a laser beam And a laser beam application means for applying the laser beam.
Position information storage means for storing position information of a plurality of electrode pads formed on each device together with position information on each device on the wafer;
An ellipse for generating an elliptical orbit including a circle passing through four electrode pads arranged at the same position based on positional information of the two electrodes and four devices adjacent to each other as a group Trajectory generating means;
Elliptical orbit positioning means for positioning the elliptical orbit at a position corresponding to the four electrode pads to be processed;
Laser beam irradiating means for irradiating a pulse laser beam to positions corresponding to the four electrode pads while drawing the elliptical orbit;
A laser processing apparatus for forming a via hole by operating the laser beam irradiation means and the elliptical orbit positioning means while relatively processing and feeding a wafer and a pulsed laser beam. The laser beam application means includes an oscillator which oscillates a pulse laser beam at a repetition frequency M which is a multiple of 4 and a condenser which condenses the pulse laser beam oscillated by the oscillator onto a wafer held by the holding means,
The elliptical orbit generating means is disposed between the oscillator and the condenser, and is an X-axis resonant scanner that oscillates the irradiation direction of the laser beam in the X-axis direction at a repetition frequency of 1⁄4 of the repetition frequency M; And Y-axis resonant scanner that swings the irradiation direction of the laser beam in the Y-axis direction at a repetition frequency of 1⁄4 of the repetition frequency M, and pulses are provided to each electrode pad whose position information is stored in the position information storage means Generate an elliptical trajectory to distribute the laser beam,
The elliptical orbit positioning means comprises an X axis scanner which moves the elliptical orbit generated by the elliptic orbit generating means in the X axis direction, and a Y axis scanner which moves the elliptical orbit in the Y axis direction. The laser processing apparatus according to claim 6, wherein the elliptical trajectory is positioned so as to pass through the four electrode pads to be processed based on the position information of the electrode pads stored in the position information storage means.   The laser processing apparatus according to claim 7, wherein the sine curve generated by the X-axis resonant scanner is out of phase by π / 2 with respect to the sine curve generated by the Y-axis resonant scanner.