JP5243139B2 - Laser processing apparatus and laser processing method - Google Patents

Description

  The present invention relates to an apparatus and method for processing a workpiece such as a semiconductor wafer using a laser beam. More specifically, the present invention relates to a technique for forming a modified region on a work division planned line by irradiating a laser beam from the back side of the work.

  In the manufacturing process of a semiconductor device, a circuit such as an IC (integrated circuit) or an LSI (large-scale integration) is formed in a matrix on the surface of a substantially disc-shaped semiconductor wafer, Thereafter, the wafer on which the plurality of circuits are formed is cut into a lattice shape along a predetermined street (cutting line) to separate each circuit into chips.

  Usually, a cutting device called a dicer is used for cutting (dicing) a semiconductor wafer. In recent years, a method of cutting a workpiece such as a semiconductor wafer using a laser beam has been developed. For example, in the processing method described in Patent Document 1, a workpiece made of an oxide single crystal is irradiated with laser light, and the molecules of the oxide single crystal are dissociated and evaporated by a photochemical reaction, whereby a predetermined position of the workpiece is obtained. A groove is formed in the workpiece, and the workpiece is cleaved along the groove.

  Further, in the cutting method described in Patent Document 2, pulsed laser light having transparency to the work is irradiated to the inside of the work with a converging point, and an altered region is formed along the planned division line. . Since this deteriorated region has a lower strength than the other portions, the work is divided by applying the external force along the planned dividing line and starting from the deteriorated layer.

  On the other hand, for workpieces with irregularities on the surface, such as MEMS (Micro Electro Mechanical Systems), and workpieces with TEGs formed on the lines to be divided, the laser beam reaches the inside of the workpiece due to the irregularities and TEGs. There may not be. In particular, these effects are large in a work having a wide unevenness and a work having devices with narrow pitches and narrow streets.

  Therefore, conventionally, a method of irradiating a laser beam from the back side without a film or unevenness when forming a deteriorated layer in a workpiece has been proposed. For example, in the laser processing methods described in Patent Literature 3 and Patent Literature 4, a workpiece is placed on a chuck table with the front side facing down, and a laser is applied to the inside of the workpiece via a dicing film attached to the back surface of the workpiece. Irradiating light. In these methods, the influence of the laser beam on the dicing film and the energy loss of the laser beam are reduced by using laser light having a wavelength having transparency for both the dicing film and the workpiece.

  Further, in the cleaving method described in Patent Document 5, a dicing tape having adhesiveness on both sides is used, and a work held on the ring frame via the dicing tape is placed on a transparent support plate made of glass or the like. It is placed. The back surface of the workpiece is irradiated with laser light through the transparent support plate and the dicing tape.

JP-A-10-305420 JP 2002-192370 A JP 2006-148175 A JP 2007-173475 A JP 2008-132710 A

  Processes leading to the dicing process for workpieces with various materials formed on the surface such as semiconductor wafers and workpieces with devices formed on the surface such as MEMS (Micro Electro Mechanical Systems) The work may be warped or swelled. Such warping and undulation cause a shift in the irradiation position of the laser beam on the workpiece and a shift in the focal position of the laser beam inside the workpiece, causing a reduction in processing accuracy.

  If the workpiece has warping or undulation, it is desirable to adjust the focal position of the laser light according to the degree. A piezo element is used as a mechanism for adjusting the condensing position in the thickness direction of the workpiece, and the adjustable range of the condensing position is greatly influenced by the performance of the element. For this reason, there is no problem as long as the displacement of the workpiece is within an adjustable range, but when the degree of warping or waviness is large, the condensing point position of the laser beam cannot be adjusted according to the displacement of the workpiece. There is. Therefore, in order to obtain high machining accuracy, it is considered necessary to correct the warping and undulation of the work in advance to the extent that the focal position of the laser beam can be followed.

  In view of the above, a main object of the present invention is to provide a laser processing apparatus and a laser processing method capable of correcting a warp and undulation generated in a workpiece and irradiating laser light with high accuracy.

  In order to solve the above problems, the present invention provides a laser processing apparatus for forming a modified region inside a workpiece having a plurality of devices formed on the surface, wherein (1) the region on which the device is formed on the workpiece surface And a peripheral portion having a holding surface that stands and surrounds the concave portion and has a holding surface that contacts and holds a region where the device is not formed, which is provided on a peripheral portion of the work surface. Means, (2) displacement detection means for detecting the displacement of the workpiece, (3) pressure adjusting means for adjusting the pressure in the space formed by the workpiece, the concave portion and the outer peripheral portion, and the back surface of the workpiece And a laser beam irradiating means for irradiating a laser beam having a wavelength that passes through the workpiece toward the workpiece.

  In this laser processing apparatus, the pressure adjusting means is (3A) the pressure adjusting means is a blow means for introducing air into the space based on a signal output from the displacement detecting means; And an exhaust means for exhausting air from the air. By this pressure adjusting means, the work is warped and / or sucked by suctioning the work to the holding means side with negative pressure in the space, or pushing the work to the laser light irradiation means side with positive pressure in the space. Or swell can be corrected. When the pressure adjusting means is configured as a blow means and an exhaust means, the displacement detection means may be arranged at a position facing the work surface of the recess. Further, the space may be divided into a plurality of sections along the workpiece surface direction, and the blow means, the exhaust means, and the displacement detection means may be arranged for each of the sections.

  In this laser processing apparatus, the pressure adjusting means may include (3B) airflow forming means for injecting an airflow along the workpiece surface direction in the space. According to this pressure adjusting means, it is possible to correct warping and / or waviness of the workpiece based on the Bernoulli effect caused by the airflow. When the pressure adjusting unit is configured as an air flow forming unit, it is preferable that a cutout for allowing the air flow to flow out of the space is provided in the outer peripheral portion.

  The present invention also irradiates a workpiece having a plurality of devices formed on the front surface and supported by the opening of the annular frame via an adhesive tape attached to the rear surface, A laser processing method for forming a modified region, comprising: (1) a recess facing the region on the workpiece surface where the device is formed; and a standing portion surrounding the recess, A step of holding the workpiece by a holding means having a holding surface that holds and holds a region where the device is not formed, and (2) a step of detecting displacement of the workpiece; (3) adjusting the pressure in the space formed by the workpiece, the concave portion and the outer peripheral portion based on the detected displacement, and correcting the warpage and / or waviness of the workpiece; ) From the back side of the click, a laser beam having a wavelength that passes through the workpiece and the adhesive tape, focused on the work inside, provides a laser processing method and a step of irradiating along the dividing lines.

  According to the present invention, there are provided a laser processing apparatus and a laser processing method capable of correcting a warp and undulation generated in a workpiece and irradiating laser light with high accuracy.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. In addition, this invention is not limited to embodiment shown below.

1. Laser processing equipment 1
First, the configuration of the laser processing apparatus according to the first embodiment of the present invention will be outlined with reference to FIGS. FIG. 1 is a perspective view showing a configuration of a laser processing apparatus. FIG. 2 is a perspective view showing a specific configuration of the holding means 2 shown in FIG.

  In FIG. 1, a laser processing apparatus 1 denoted by reference numeral 1 includes at least a holding unit 2 that holds a workpiece 10, a laser beam irradiation unit 3 that irradiates a predetermined position on the workpiece 10, and a displacement of the workpiece 10. Displacement detecting means 4 is provided.

  Workpieces 10 to be processed by the laser processing apparatus 1 include, for example, semiconductor wafers, adhesive tapes such as DAF (Die Attach Film), various substrates made of inorganic materials such as glass, silicon and sapphire, metal materials or plastics, and semiconductors. Product packages and various processing materials that require micron-order accuracy are included. As shown in FIG. 2, these works 10 have an adhesive tape 10 affixed to the back surface thereof, and are supported by the openings of the ring frame 11 via the adhesive tape 10. Then, it is processed while being supported by the ring frame 11.

  The holding means 2 includes an annular holding surface that holds and holds the concave portion 21a facing the region where the device 10a is formed on the surface of the workpiece 10 and the region 10b provided on the peripheral portion of the surface of the workpiece 10 where the device 10a is not formed. And an outer peripheral portion 21b. The outer peripheral portion 21b is erected so as to surround the concave portion 21a. In FIG. 2, reference numeral 22 denotes a clamp for detachably fixing the ring frame 11. One or more clamps 22 may be provided on the holding means 2.

  The holding means 2 can be moved in the x-axis direction and the y-axis direction in FIG. 1 by the feeding means. Specifically, a ball screw 33a is arranged between a pair of guide rails 32a and 32b arranged parallel to each other on the base 31, and a motor 33b is attached to one end of the ball screw 33a. The other end is rotatably supported by the bearing block 33c.

  A sliding block 34 is placed on the guide rails 32a and 32b and the ball screw 33a. On the sliding block 34, a pair of guide rails 35a and 35b and a ball screw 36a are arranged in parallel to each other. Has been. The ball screw 36a also has a motor 36b attached to one end, and the other end is rotatably supported by the bearing block 36c. Further, a sliding block 37 is placed on the guide rails 35a and 35b and the ball screw 36a, and the holding means 2 is installed on the sliding block 37.

  In the feeding means constituted by these members, when the ball screw 33a is driven by the motor 33b, the sliding block 34 is guided and moved by the guide rails 32a and 32b, whereby the holding means 2 is moved in the x-axis direction. Move to. On the other hand, when the ball screw 36a is driven by the motor 36b, the sliding block 37 is guided and moved by the guide rails 35a and 35b, thereby moving the holding means 2 in the y-axis direction.

  The laser beam irradiation means 3 is disposed above the holding means 2, and an oscillator capable of oscillating a laser beam having a wavelength that passes through the workpiece 10 such as a YAG laser oscillator or a YVO laser oscillator, and an oscillated laser beam. Are provided with optical components such as a mirror and a condensing lens.

  The laser beam irradiation means 3 is provided with a mechanism for controlling the focal position of the laser beam. This focal position adjustment mechanism is configured by moving the condensing lens in the Z-axis direction in FIG. 1 using, for example, a voice coil or a piezo element, and warping or waviness or unevenness of the workpiece 10 (hereinafter simply referred to as “warping”). ) To adjust the focal position of the laser beam in the z-axis direction in FIG.

  The displacement detection means 4 detects a displacement indicating the warp of the workpiece 10. The configuration and method of the displacement detection unit 4 are not particularly limited. For example, a laser beam irradiation unit including a laser oscillator and a laser beam detection unit including a sensor are installed above the holding unit 2. The laser beam having a wavelength reflected by the surface of the workpiece 10 can be irradiated to the workpiece 10 and the reflected light can be detected. In this case, the amount of reflected light is measured in the laser light detection unit, and the change in the distance from the back surface of the work 10 to the laser light detection unit, that is, the displacement of the work 10 can be obtained from the change in the value. For example, when the workpiece 10 is a semiconductor wafer using a silicon substrate, the workpiece 10 is irradiated with a laser beam having a wavelength of 635 nm having reflectivity, and the change in the amount of reflected light is measured. It is possible to measure the displacement of the back surface of the plate. Note that the configuration and detection method of the displacement detection means are not particularly limited as long as the displacement of the workpiece 10 can be detected. For example, in the laser processing apparatus 1 shown in FIG. 1, the displacement detection means 4 and the laser light irradiation means 3 are provided separately. However, these are integrated so that the processing laser light and the displacement measurement laser light are combined. It may be coaxial.

  Next, the configuration of the laser processing apparatus 1 will be described more specifically with reference to FIG. 3 and FIG. 3 and 4 are cross-sectional views showing a part of the configuration of the laser processing apparatus 1. FIG. In these drawings, illustration of a part of the configuration (pressure adjusting means 7 or suction means 6) is omitted.

  In the holding means 2, a recess 21a is formed at a position facing the region where the device 10a is formed on the surface of the workpiece 10. Further, an outer peripheral portion 21b having an annular holding surface that contacts and holds the region 10b in which the device provided on the peripheral portion of the surface of the workpiece 10 is not formed is formed surrounding the concave portion 21a. The outer peripheral portion 21b that holds the workpiece 10 in contact is formed so that its inner diameter is smaller than the outer diameter of the entire workpiece 10 and larger than the outer diameter of the region of the workpiece 10 where the device 10a is formed.

  That is, when the work 10 is placed on the holding means 2 with the back surface facing the laser beam irradiation means 3, the outer peripheral portion 21b is a region where the device 10a provided on the peripheral edge of the work 10 is not formed (surplus) (Region) 10b is brought into contact only. Thereby, in the laser processing apparatus 1, the holding means 2 holds the workpiece 10 without touching the device 10a, so that the deformation of the device 10a during processing can be prevented.

  Further, the holding means 2 is provided with suction means 6 having an opening at a portion that contacts the surplus region 10b of the outer peripheral portion 21b. The suction means 6 is constituted by a normally used decompression pump or the like. The suction means 6 is connected to an opening provided in a portion in contact with the surplus region 10b of the outer peripheral portion 21b, and sucks air from the opening. Thereby, the surplus area 10b of the workpiece 10 can be sucked into the opening, and the workpiece 10 can be stably adsorbed and held on the outer peripheral portion 21b.

  A workpiece such as a semiconductor wafer may be warped in the process up to the dicing process. According to the focal position adjusting mechanism provided in the laser light irradiation means 3, by adjusting the focal position of the laser light in accordance with the warp of the workpiece 10, it is possible to follow to some extent against such displacement. However, with a mechanism that adjusts the focal position using a general piezo element, the adjustable range of the condensing position largely depends on the performance of the element, and sufficient follow-up is not possible if the degree of warpage or undulation is large. There is. For this reason, the laser beam irradiation means 3 cannot compensate for the warp of the workpiece 10 and the focal position of the laser beam 5 in the workpiece 10 is displaced.

  Therefore, in the laser processing apparatus 1, in order to correct a large warp of the work that cannot be followed by the focal position adjustment mechanism, as shown in FIG. 4, it is formed by the work 10, the concave portion 21a, and the outer peripheral portion 21b. Pressure adjusting means 7 for adjusting the pressure in the space 102 is provided. The pressure adjusting means 7 includes a blow means 71 and an exhaust means 72.

  The blow means 71 is configured by a normally used pressure pump or the like, is connected to an introduction port 711 that opens in the recess 21a, and introduces air into the space 102 from the introduction port 711. This air can be pressurized. One or more introduction ports 711 are provided on the bottom surface of the concave portion 21a or on the wall surface continuous with the concave portion 21a of the outer peripheral portion 21b erected so as to surround the concave portion 21a.

  The exhaust means 72 is constituted by a normally used decompression pump or the like, connected to an introduction port 721 that opens in the recess 21a, and exhausts air from the exhaust port 721 to the outside of the space 102. One or more discharge ports 721 are also provided on the bottom surface of the concave portion 21a or on the wall surface continuous with the concave portion 21a of the outer peripheral portion 21b erected so as to surround the concave portion 21a.

  The blow means 71 and the exhaust means 72 are connected to the displacement measuring means 4, and based on the displacement of the workpiece 10 measured by the displacement measuring means 4, the flow rate of the air introduced into the space 102 or the discharged air is determined. Control.

  In the laser processing apparatus 1, the pressure adjustment means 7 adjusts the pressure in the space 102 formed by the work 10 placed on the holding means 2, the concave portion 21a, and the outer peripheral portion 21b, thereby warping the work. Can be corrected.

2. Operation of Laser Processing Apparatus 1 Next, the operation of the laser processing apparatus 1, that is, a method for processing the workpiece 10 using the laser processing apparatus 1 will be described.

  As shown in FIG. 3, in the laser processing method according to the present embodiment, first, the workpiece 10 to be processed is supported on the opening of the ring frame 11 via the adhesive tape 12. At this time, the adhesive tape 12 is attached to the back surface of the workpiece 10.

  Next, the work 10 supported by the ring frame 11 is placed on the holding means 2 of the laser processing apparatus 1 with the back surface facing the laser beam irradiation means 3 side, and fixed by the clamp 22. In this state, the surplus area 10b provided at the peripheral edge portion of the workpiece 10 is held in contact with the outer peripheral portion 21b. Furthermore, by using the suction means 6 described with reference to FIG. 3, it is possible to suck the surplus area 10b and stably hold the workpiece 10 on the outer peripheral portion 21b.

  Then, the displacement detection means 4 detects the displacement of the workpiece 10 indicating warpage, undulation, and unevenness. When the displacement detection means 4 detects that the workpiece 10 has a “convex on the back side” warp that cannot be followed by the focal position adjustment mechanism, the pressure adjustment means 7 outputs a signal from the displacement detection means 4 In response, the pressure in the space 102 formed by the workpiece 10, the concave portion 21a, and the outer peripheral portion 21b is adjusted to be a negative pressure rather than the external pressure. That is, the exhaust means 72 discharges air from the discharge port 721 and reduces the pressure in the space 102. Thereby, since the workpiece | work 10 is attracted | sucked to the holding means 2 side, the convex curvature on the back side is corrected.

  On the other hand, when the displacement detecting means 4 detects that the workpiece 10 has a “convex to the front side” warp that cannot be followed by the focal position adjusting mechanism, the pressure adjusting means 7 Adjust the pressure so that it is more positive than the external pressure. That is, the blow means 71 introduces air from the introduction port 711 to increase the pressure in the space 102. Thereby, since the workpiece | work 10 is extruded to the laser irradiation means 3 side, convex curvature is corrected to the surface side.

  The displacement detection means 4 can detect the displacement indicating the warp of the workpiece 10 or the like repeatedly until no warp that cannot be followed by the focus position adjusting mechanism is detected. That is, a signal output related to the warpage of the workpiece from the displacement detection means 4 and the pressure adjustment in the space 102 by the pressure adjustment means 7 based on this signal are repeatedly performed, and the warpage of the workpiece 10 can be followed by the focal position adjustment mechanism. Continue until convergence.

  The pressure adjustment in the space 102 by the pressure adjustment means 7 based on the signal output related to the warp of the workpiece from the displacement detection means 4 is more accurate by providing a pressure detection unit (not shown) for detecting the pressure in the space 102. Can be done. In this case, the pressure detection unit is disposed facing the inside of the space 102 on the bottom surface of the recess 21a or on the wall surface continuous with the recess 21a of the outer peripheral portion 21b erected so as to surround the recess 21a. The pressure measurement result in the space 102 by the pressure detection unit is output to the pressure adjustment unit 7, and the pressure adjustment unit 7 adjusts the pressure in the space 102 based on both signals input from the displacement detection unit 4 and the pressure detection unit. .

  In the case where the same type of workpiece is continuously processed by the laser processing apparatus 1, if the workpieces are uniformly warped, the displacement detection step by the displacement detection means 4 should be omitted. You can also. In this case, the laser processing apparatus 1 is provided with storage means for holding information about the warp obtained in advance for the workpiece, and the pressure adjusting means 7 is referred to this information, thereby adjusting the pressure in the space 102. .

  After correcting the warpage and making the displacement of the workpiece within the range that can be followed by the focal position adjusting mechanism, as shown in FIG. 3, from the back side of the workpiece 10, the wavelength of the wavelength that transmits the adhesive tape 12 and the workpiece 10 is increased. The laser beam 5 is irradiated while focusing on the inside of the workpiece 10 while moving the condenser lens so as to follow the displacement. The laser beam 5 is irradiated along the division line. For example, when the workpiece 10 is a semiconductor wafer using a silicon substrate, pulse laser light having a wavelength of 1064 nm is irradiated. As a result, a modified region is formed on the division line of the workpiece 10.

  At this time, the position of the division line of the workpiece 10 is reflected from the surface of the workpiece 10 by irradiating light that passes through the workpiece 10 such as infrared rays from the back surface of the workpiece 10 through the adhesive tape 12, for example. This can be confirmed by detecting light.

  The workpiece 10 in which the reformed region is formed on the planned dividing line by the above-described process can be easily and accurately divided along the planned dividing line by applying an external force and starting from the modified region. it can.

  As described above, in the laser processing apparatus 1, when the workpiece 10 has a “convex on the back side” warpage, the pressure adjustment means 7 causes the space 102 to be a negative pressure and the workpiece 10 is moved to the holding means 2 side. Warping can be corrected by suction. Also, if there is a “convex on the surface side” warp, the warp can be corrected by making the inside of the space 102 positive pressure by the pressure adjusting means 7 and pushing the workpiece 10 toward the laser light irradiation means 3 side. Is possible.

  Thereby, in the laser processing apparatus 1, the back surface of the work 10 irradiated with the laser light can be made substantially flat, and the warp of the work 10 can be corrected to a range in which the focal position of the laser light can be followed. For this reason, even when the focal position adjustment mechanism provided in the laser beam irradiation means 3 is configured using a general piezo element, the warp of the workpiece is sufficiently compensated, and the laser beam irradiation position and workpiece The focal position of the laser beam inside can be kept constant. As a result, it is possible to perform highly accurate processing along the cutting line or the division line.

  In the laser processing apparatus 1 described above, the displacement detection means 4 installed above the holding means 2 is configured to simultaneously detect displacements outside and within the followable range by the focus position adjustment mechanism. Detection can also be performed by the displacement detection means 4 provided on the body.

  FIG. 5 is a perspective view showing a configuration of a modified example of the holding means 2 of the laser processing apparatus 1 in which the displacement detection means 4 is arranged at a position facing the work surface of the concave portion 21a of the holding means 2. FIG.

  The recess 21a of the holding means 2 of the modification shown in FIG. 5 is divided into four sections 211a, 212a, 213a, and 214a by partition walls along the surface direction of the held work. Thereby, when the work supported by the ring frame is placed on the holding means 2, the space 102 formed by the work, the concave portion 21a and the outer peripheral portion 21b has four spaces corresponding to the sections 211a, 212a, 213a and 214a. Divided into space.

  In the partitions 211a, 212a, 213a, 214a, the displacement detection means 4, the introduction port 711, and the discharge port 721 are arranged, respectively. The displacement detecting means 4 is arranged at a position facing the workpiece surface of the sections 211a, 212a, 213a, 214a. As described above, the displacement detection means 4 is composed of a laser beam irradiation unit and a laser beam detection unit, etc., and detects the reflected light by irradiating the surface of the workpiece with the laser beam, in particular, the displacement of the workpiece. It measures the displacement that cannot be followed by the focal position adjustment mechanism. The introduction port 711 and the discharge port 721 arranged in each section are connected to the blow unit 71 and the exhaust unit 72, respectively. The blow means 71 and the exhaust means 72 connected to each section are configured as independent pressure adjusting means 7, and the pressure in the space 102 divided into four can be adjusted independently. .

  That is, when the displacement detecting means 4 arranged in each section detects a displacement of a part of the workpiece located on each section, the pressure adjusting means 7 arranged in each section receives a signal output from the displacement detecting means 4. The internal pressure is adjusted by controlling the flow rate of air introduced into each compartment or exhausted air.

  By independently adjusting the pressure in each section in this way, in the laser processing apparatus provided with the holding means 2 of this modification, a displacement that cannot be followed by the focal position adjustment mechanism is detected in the entire workpiece. It is possible to correct the warpage of the specific area, and it is possible to correct the warpage more precisely.

  In addition, in the laser processing apparatus of this modified example, by arranging a plurality of displacement detection means 4 on the holding means 2 side, the warpage can be measured while the work is transported to the processing position, and the work piece can be measured at any time during processing. It becomes possible to correct the warp.

  That is, when one displacement detection means is provided in the vicinity of the laser light irradiation means (see FIG. 1), in order to measure the displacement of the workpiece by the displacement detection means, the work must first be placed at the machining position. Is required. Also, in this case, once the machining is started after the displacement detected by the displacement detecting means is corrected to the range in which the focus position adjusting mechanism can follow, even if the workpiece being machined is warped again, It is difficult to detect and correct properly. This is because once the machining is started, the displacement detecting means is driven integrally with the laser light irradiating means for irradiating the laser light along the planned division line of the workpiece, and a followable displacement for adjusting the focal position of the laser light. This is because it will function to detect this.

  On the other hand, in the laser processing apparatus provided with the holding means 2 of the present modified example, the displacement detecting means 4 is arranged in each section of the holding means 2 in addition to the vicinity of the laser light irradiation means 3, so that the workpiece is While transporting to the processing position, the displacement can be measured by the displacement detection means 4 arranged in each section. Thereby, the time required for processing can be shortened and tact-up can be achieved.

  Further, in the laser processing apparatus of this modified example, the displacement detection means 4 provided in the vicinity of the laser light irradiation means 3 during processing functions on the holding means 2 side even when the displacement detection function functions. The displacement of the workpiece can be detected at any time by the displacement detecting means 4, and correction by the pressure adjusting means 7 can be performed. For this reason, it is possible to prevent a displacement that the focal position adjusting mechanism cannot follow the workpiece being processed, to stably hold the workpiece, and to perform more precise processing.

  Here, the case where the concave portion 21a of the holding means 2 is divided into four sections has been described as an example, but the number of sections can be arbitrary, and a large number of sections can be formed by increasing the number of partition walls formed in the concave section 21a. Can do. Further, the displacement detection means 4, the introduction port 711, and the discharge port 721 provided in each section are not limited to one, and two or more may be arranged.

  By forming a large number of sections in the recess 21a of the holding means 2 and disposing the displacement detecting means 4 etc. in each section, the warp can be corrected more precisely.

3. Laser processing equipment 2
Next, a laser processing apparatus according to a second embodiment of the present invention will be described with reference to FIG. The figure shows a part of the configuration of the laser processing apparatus according to the second embodiment of the present invention. (A) is a top view of the recessed part 21a and the outer peripheral part 21b of the holding means 2, (b) respond | corresponds to sectional drawing corresponding to an AA cross section in (a).

  As shown in FIGS. 6 (a) and 6 (b), in the laser processing apparatus 2 of the present embodiment, an air nozzle 8 is provided in the recess 21a of the holding means 2. This air nozzle 8 has an airflow along the workpiece surface direction (parallel to the recess 21a) in the space 102 formed by the workpiece 10, the recess 21a, and the outer peripheral portion 21b (the arrow in the figure (a)). In addition, it functions as an air flow forming unit that injects the air in a plurality of directions and serves as a pressure adjusting unit that generates a negative pressure around the air flow (air).

  Further, as shown in FIG. 6 (a), a plurality of steps are formed on the upper surface of the outer peripheral portion 21b. Of the upper surface of the outer peripheral portion 21b, the upper surface of the portion having a high height serves as a holding surface 211b for holding the workpiece 10 in contact. The holding surface 211b is formed with one or a plurality of apertures 61 connected to the suction means 6. The suction means 6 sucks air from the opening 61 to suck the surplus area 10b of the workpiece 10 into the opening, and stably holds the workpiece 10 on the outer peripheral portion 21b.

  Of the upper surface of the outer peripheral portion 21b, a portion having a low height becomes a notch 212b through which air jetted from the air nozzle 8 flows. When the workpiece 10 is placed on the holding means 2, a gap is generated between the workpiece 10 and the portion where the height of the upper surface of the outer peripheral portion 21b is low. The air jetted from the air nozzle 8 substantially in parallel with the concave portion 21a flows outside the space 102 through this gap.

  Here, the notch 212b for allowing air to flow is provided by forming a part of the upper surface of the outer peripheral portion 21b one step lower than the holding surface 211b and forming a gap with the workpiece 10. The configuration of the notch 212b is not limited to this, and can be widely adopted as long as air can flow through the missing portion by missing a portion of the outer peripheral portion 21b. Specifically, for example, an exhaust hole penetrating the outer peripheral portion 21b in a direction substantially parallel to the concave portion 21a may be provided to allow air to flow.

4). Operation of Laser Processing Device 2 Next, the operation of the laser processing device 2, that is, the processing method of the workpiece 10 using the laser processing device 2 will be described. The configuration other than the above in the laser processing apparatus of the present embodiment is the same as that of the laser processing apparatus 1 described above.

  As shown in FIG. 6 (b), in the laser processing method of the present embodiment, first, the work 10 supported by the opening of the ring frame 11 via the adhesive sheet 12 is placed on the back surface on the laser irradiation means side. In this state, the ring frame 11 is fixed on the holding means 2 with the clamp 22.

  Next, the displacement detection means 4 (see also FIG. 1) detects a displacement indicating warpage of the workpiece 10. When it is detected by the displacement detecting means 4 that the workpiece 10 is warped “convex on the back side”, air is injected from the air nozzle 8 toward the notch 212b at a predetermined flow rate and flow velocity. As a result, due to the Bernoulli effect of air along the workpiece surface direction, the periphery of the air is adjusted to a negative pressure, and the workpiece 10 is attracted to the air. As a result, the warp of the workpiece 10 is corrected.

  Thereafter, as in the processing method of the first embodiment, from the back side of the workpiece 10, the laser beam having a wavelength that passes through the workpiece 10 and the adhesive tape 12 is aligned with the condensing point inside the workpiece 10, and the line to be divided The modified region is formed on the workpiece 10 by irradiating along the workpiece 10.

  In the laser processing apparatus 2, the “convex to the back side” warpage of the workpiece 10 is corrected by the Bernoulli effect caused by the air jetted from the air nozzle 8. According to this method, since the air in the space 102 becomes a barrier, the workpiece 10 is not attracted more than necessary to the concave portion 21a side. Therefore, the warp of the workpiece 10 can be corrected and held at a fixed position by a simple operation of simply ejecting air. Therefore, in the laser processing device 2, as described in the laser processing device 1 described above, the displacement detection unit 4 repeatedly detects the displacement of the workpiece 10, and the pressure adjustment unit until the warpage of the workpiece 10 converges to a certain range. Control such as repeatedly adjusting the pressure in the space 102 by 7 becomes unnecessary. As a result, according to the laser processing apparatus 2, the apparatus configuration can be simplified, and the time required to correct the warpage of the workpiece can also be shortened.

  In the laser processing apparatuses 1 and 2 described above, when the work 10 is placed on the holding means 2 with the back surface facing the laser light irradiation means 3, the outer peripheral portion 21b comes into contact with only the surplus area 10b. It has become. Thereby, in the laser processing apparatus 1, since the holding means 2 holds the workpiece 10 without touching the device 10a, it is possible to reduce the occurrence of defects due to deformation of the device 10a and improve the yield.

  These laser processing devices can be applied to the processing of various workpieces described above. In particular, when laser light is irradiated from the surface side like an LED (Light Emitting Diode) element, the influence of the laser light. The film may be altered or the element may melt, the dust generated by laser light irradiation may adhere to the element, causing problems, or the surface of MEMS or other materials may be finely processed. It is suitable for processing such as those in which TEG is formed on the surface of the planned dividing line and those in which the width of the planned dividing line is narrow.

1 is a perspective view showing a configuration of a laser processing apparatus 1 according to a first embodiment of the present invention. It is a perspective view which shows the specific structure of the holding means 2 shown in FIG. It is sectional drawing which shows a part of structure of the laser processing apparatus which concerns on this invention. It is sectional drawing which shows a part of structure of the laser processing apparatus which concerns on this invention. 6 is a perspective view showing a configuration of a modified example of the holding means 2 of the laser processing apparatus 1. FIG. FIG. 5 is a diagram showing a part of the configuration of a laser processing apparatus 2 according to a second embodiment of the present invention. (A) is a top view of the recessed part 21a and the outer peripheral part 21b of the holding means 2, (b) is sectional drawing corresponding to an AA cross section in (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser processing apparatus 2 Holding means 3 Laser beam irradiation means 4 Displacement detection means 5 Laser light 6 Suction means 7 Pressure adjustment means 71 Blow means 711 Inlet 72 Evacuation means 721 Ejection port 8 Air nozzle 10 Work 10a Device 10b Surplus area 102 Space 11 Ring frame 12 Adhesive tape 21a Recessed portion 211a, 212a, 213a, 214a Partition 21b Outer peripheral portion 211b Holding surface 212b Notch 22 Clamp 31 Base 32a, 32b, 35a, 35b Guide rail 33a, 36a Ball screw 33b, 36b Motor 33c, 36c Bearing Block 34, 37 Sliding block

Claims (1)

A plurality of devices are formed on the front surface, and a workpiece is supported on the opening of the annular frame via an adhesive tape attached to the back surface, and a laser beam is irradiated to form a modified region in the workpiece. A laser processing method,
A recess facing the region where the device is formed on the workpiece surface;
The work is held by holding means provided with an outer peripheral part having a holding surface that stands and surrounds the concave part and that is provided at a peripheral part of the work surface and does not form the device. And a process of
Detecting the displacement of the workpiece;
Adjusting the pressure in the space formed by the workpiece, the concave portion and the outer peripheral portion based on the detected displacement, and correcting the warpage and / or undulation of the workpiece;
From the back side of the workpiece, a laser beam having a wavelength that passes through the workpiece and the adhesive tape is focused on the inside of the workpiece and irradiated along a planned division line.
In the step of correcting the warp and / or waviness of the workpiece, when the warp and / or waviness that cannot be followed by the focus position adjusting mechanism occurs in the work, the warp and / or waviness of the work is caused by the focus position adjusting mechanism. A laser processing method that corrects the workpiece until it converges to the followable range .

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