KR20130096650A - Chuck table and wafer laser beam machining method using the same - Google Patents

Abstract

PURPOSE: A chuck table and a laser processing method of a wafer using the chuck table are provided to detect the outer peripheral edge of the wafer without errors by being not affected by droplets or bubbles. CONSTITUTION: A chuck table (10) holds a wafer at a holding surface (11a) by interposing adhesive tape. The wafer is adhered to a ring-shaped frame by interposing the adhesive tape. Multiple devices are divided by first and second streets on the surface of the wafer. The chuck table includes a suction path connected to a suction source (12), a holding member (11), and an LED (14). The holding member includes a suction region (16) holding the wafer by negative pressure from the suction path and a light transmission region (17) surrounding the suction region.

Description

CHUCK TABLE AND WAFER LASER BEAM MACHINING METHOD USING THE SAME

This invention relates to the laser processing method of the wafer which irradiates a laser beam along the dividing scheduled line formed in the wafer, and forms a laser processing groove along the dividing scheduled line in a wafer.

The laser beam is irradiated with a laser beam on a parting line of a semiconductor wafer on which devices such as an integrated circuit (IC) and a large scale integration (LSI), or a sapphire wafer on which a device such as a light emitting diode (LED) device is formed. By dividing a groove into the surface, it divides into individual devices, and electronic devices, such as a mobile telephone, a personal computer (PC), and an LED light, are manufactured.

In order to perform laser processing on a semiconductor wafer, the laser beam of the wavelength which has absorptivity with respect to a wafer is irradiated with the semiconductor wafer which adhered to the dicing tape on the chuck table. At this time, when the laser beam is irradiated out of the outer peripheral edge of the semiconductor wafer, the dicing tape is heated and welded to adhere to the workpiece holding region of the chuck table. This adhered dicing tape has a problem that the empty hole for sucking the vacuum formed in the workpiece holding region is blocked, or the surface precision of the workpiece holding region is lowered. For this reason, it is necessary to scrape the dicing tape affixed to the to-be-processed object holding | maintenance part with grindstone, and the chuck table must be replaced in some cases. Thus, a part of the outer circumferential edge of the wafer is picked up, and the position of the outer circumferential edge of the wafer is detected from the image obtained by the picked-up image, and the position of the entire outer circumferential edge of the wafer is determined from the coordinate position of the detected outer circumferential edge. The method which detects and prevents a laser beam from processing outside the outer peripheral edge of a wafer is taken (for example, refer patent document 1).

In addition, the technique of forming a laser processing groove by irradiating a laser beam to a wafer is useful in the removal of a weak low-k film, which is difficult to cut a blade by a dicing apparatus used in the past, the processing of a very hard material (such as sapphire), and the like. It has been intended to be used. However, debris occurs due to the concentration of thermal energy in the area irradiated with the laser beam, and when the debris adheres to the device surface, there is a problem of degrading the quality of the device. Therefore, recently, water-soluble resins such as PVA (polyvinyl alcohol) and PEG (polyethylene glycol) are coated on the upper surface of the wafer in advance to coat a protective film, and the laser beam is irradiated onto the wafer through the protective film. The processing method has also been used (for example, refer patent document 2).

Patent Document 1: Japanese Unexamined Patent Publication No. 2008-053341 Patent Document 2: Japanese Patent Application Laid-Open No. 2004-322168

However, at the time of coating a protective film, the droplet and bubble of water-soluble resin generate | occur | produce in any way from the nozzle which discharges water-soluble resin. If these droplets and bubbles adhere to the tape near the outer circumferential edge of the wafer, a misrecognition occurs at the time of aligning the outer circumferential edge of the wafer, resulting in a problem of incorrectly detecting the position of the entire outer circumferential edge of the wafer. there was.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and an object thereof is to provide a chuck table and a laser processing method of a wafer using a chuck table which enables the position of the entire outer peripheral edge of the wafer to be detected without error.

In order to solve the problem mentioned above and achieve the objective, the chuck table of this invention adheres to the annular frame via the adhesive tape, and the wafer which the several device partitioned on the surface by the division | segmentation line is divided into the said adhesive tape. A chuck table held at a holding surface via a chuck table, the chuck table includes a suction path communicating with a suction source, a holding member having the holding surface on an upper surface thereof, and a light emitting body provided below the holding member, The holding member includes a suction region for sucking and holding the wafer to be disposed under negative pressure from the suction path, and a light transmitting region including a transparent or translucent member serving the suction region, and the light emitting member transmits the light. It is provided below the area | region, and the said light transmission area | region is large in outer diameter compared with the diameter of the said wafer, T and is characterized in that an inner diameter of the small circular.

A laser processing method of a wafer using the chuck table of the present invention is a laser processing method of a wafer using the chuck table, wherein the wafer is formed in an annular frame with a surface having a device formed in a region partitioned by a plurality of division scheduled lines as an upper surface. After performing the wafer sticking step of sticking through the adhesive tape, the wafer sticking step, after applying the protective material to the surface of the wafer to form a protective film, and after the protective film coating step, After performing the outer periphery edge detection step of detecting the outer periphery edge of the wafer by the imaging means by imaging the wafer placed on the chuck table via the adhesive tape, and performing the outer periphery edge detection step, The beams along the dividing line of the wafer And a laser processing groove forming step of irradiating a laser beam from the arc side to the surface of the wafer to form a laser processing groove in the wafer, wherein in the outer peripheral edge detection step, the outer peripheral edge of the wafer is chucked. The light emitting body is positioned on the light transmitting area of the table, and the light is emitted to capture the wafer.

In the laser processing method of the wafer using the chuck table and the chuck table of the present invention, the portion of the chuck table on which the outer peripheral edge of the wafer is positioned is a light transmitting region that transmits light of the light emitting body, In order to emit light, the wafer is darkly reflected on the imaging means, and the adhesive tape covering the wafer on the light transmitting area is whitened (brightly) by the influence of light from the light emitting body. Thus, since the contrast becomes clear and the captured image of the state in which the droplet and the bubble of the protective material near transparent were not seen, the position of the outer peripheral edge of the wafer is detected without being affected by the droplet or the bubble. It is possible to detect the position of the entire outer peripheral edge of the wafer without error.

Moreover, it is preferable to form suction areas other than the light transmission area | region of a chuck table with the porous ceramic etc. which are used normally. In this case, when the clamp portion provided on the outer circumference of the chuck table is used, sufficient wafer fixing is realized without providing an adsorption mechanism to the light transmitting region, so that a groove for sucking, for example, is formed in the light transmitting region. There is no need to process. For this reason, the suction-held wafer does not deform along the shape of the suction groove formed in the light transmission region, and can adversely affect the laser processing.

Moreover, it is preferable to use the material which has transparency and dispersibility with respect to the wavelength of a laser beam as the transparent or semitransparent member which comprises a light transmission area | region. In this case, even if the laser beam is irradiated to a position deviating from the outer peripheral edge of the wafer, the effect of preventing the holding surface from being damaged or melted by the laser beam is also exhibited.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structural example of the laser processing apparatus provided with the chuck table which concerns on embodiment.
2 is a perspective view illustrating a configuration of a chuck table according to the embodiment.
3 is a cross-sectional view of the chuck table taken along line III-III in FIG. 2.
It is a figure which shows the flow of the laser processing method using the chuck table which concerns on embodiment.
It is a perspective view which shows the wafer sticking step of the laser processing method using the chuck table which concerns on embodiment.
It is a perspective view which shows the protective film coating step of the laser processing method using the chuck table which concerns on embodiment.
7 is a cross-sectional view showing an outer peripheral edge detection step of the laser processing method using the chuck table according to the embodiment.
8 is a perspective view showing an outer peripheral edge detection step of the laser processing method using the chuck table according to the embodiment.
FIG. 9 is a cross-sectional view showing a main part of the outer peripheral edge detection step of the laser machining method shown in FIG. 8.
It is a figure which shows the image obtained at the outer peripheral edge detection step of the laser processing method using the chuck table which concerns on embodiment.
11 is a perspective view illustrating a laser processing groove forming step of the laser processing method using the chuck table according to the embodiment.
12 is a diagram illustrating an image obtained in a comparative example.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A mode (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments. The constituent elements described below include those which can be readily devised by those skilled in the art and substantially the same. Further, the structures described below can be suitably combined. In addition, various omission, substitution, or a change of a structure can be performed in the range which does not deviate from the summary of this invention.

[Embodiment]

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structural example of the laser processing apparatus provided with the chuck table which concerns on embodiment. 2 is a perspective view illustrating a configuration of a chuck table according to the embodiment. 3 is a cross-sectional view of the chuck table taken along line III-III in FIG. 2. It is a figure which shows the flow of the laser processing method using the chuck table which concerns on embodiment. It is a perspective view which shows the wafer sticking step of the laser processing method using the chuck table which concerns on embodiment. It is a perspective view which shows the protective film coating step of the laser processing method using the chuck table which concerns on embodiment. 7 is a cross-sectional view showing an outer peripheral edge detection step of the laser processing method using the chuck table according to the embodiment. 8 is a perspective view showing an outer peripheral edge detection step of the laser processing method using the chuck table according to the embodiment. FIG. 9 is a cross-sectional view showing a main part of the outer peripheral edge detection step of the laser machining method shown in FIG. 8. It is a figure which shows the image obtained at the outer peripheral edge detection step of the laser processing method using the chuck table which concerns on embodiment. 11 is a perspective view illustrating a laser processing groove forming step of the laser processing method using the chuck table according to the embodiment. 12 is a diagram illustrating an image obtained in a comparative example.

The chuck table 10 which concerns on this embodiment hold | maintains the wafer W adhering to the annular frame F via the adhesive tape T on the holding surface 11a via the said adhesive tape T. It is. The chuck table 10 configures the laser processing apparatus 1, for example.

The laser processing apparatus 1 coats the protective film P (shown in FIG. 7 or the like) on the wafer W once, and then holds the chuck table 10 holding the wafer W coated with the protective film P; By relatively moving the laser beam irradiation means 20, the ablation process is performed on the wafer W, and the laser processing groove S (shown in FIG. 11) is formed in the wafer W. As shown in FIG.

The laser processing apparatus 1 is comprised including the chuck table 10, the laser beam irradiation means 20, the imaging means 30, and the control means 40, as shown in FIG. . On the other hand, the laser processing apparatus 1 includes the cassette elevator 50 which accommodates the wafers W before and after laser processing, the temporary placement means 60 which temporarily arranges the wafers W before and behind laser processing, and a laser. The protective film forming and cleaning means 70 which covers the protective film P on the wafer W before processing and removes the protective film P from the wafer W after laser processing is comprised further. In addition, the laser processing apparatus 1 is an X-axis moving means which does not show the relative movement of the chuck table 10 and the laser beam irradiation means 20 to an X-axis direction, and the chuck table 10 and the laser beam irradiation means. Y-axis moving means (not shown) for relatively moving the 20 in the Y-axis direction, and Z-axis moving means (not shown) for relatively moving the chuck table 10 and the laser beam irradiation means 20 in the Z-axis direction. It is configured to include.

The cassette elevator 50 accommodates the several sheets W of the wafer W adhering to the annular frame F via the adhesive tape T. As shown in FIG. The cassette elevator 50 is provided in the apparatus main body 2 of the laser processing apparatus 1 so that lifting / lowering is possible in the Z-axis direction.

The provisional placement means 60 takes out one wafer W before laser processing from the cassette elevator 50, and accommodates the wafer W after laser processing in the cassette elevator 50. The provisional placement means 60 takes out the wafer W before the laser processing from the cassette elevator 50, and carries in / out means 61 for inserting the wafer W after the laser processing into the cassette elevator 50, and laser processing. It is comprised including the pair of rail 62 which arrange | positions the wafer W of front and back temporarily.

In the protective film formation and cleaning means 70, the wafer W before the laser processing on the pair of rails 62 is transferred by the first transfer means 81, and the protective film P is applied to the wafer W before the laser processing. ) Is to cover. In addition, the protective film formation and washing | cleaning means 70 is the wafer W after laser processing conveyed by the 2nd conveyance means 82, and removes the protective film P of the wafer W after this laser processing. As shown in FIG. 6, the protective film formation and cleaning means 70 is formed on the holding table 71 holding the wafer W and on the surface WS of the wafer W held on the holding table 71. It comprises the nozzle means 72 which apply | coats liquid resin J as a protective material, and forms the protective film P, and the washing | cleaning nozzle which is not shown in figure.

The wafer W is arranged on the holding table 71 via the adhesive tape T by the first conveying means 81 or the second conveying means 82. The holding table 71 is hold | maintained by sucking the arrange | positioned wafer W by the suction source which is not shown in figure. In addition, the holding table 71 is provided in the apparatus main body 2 so that the apparatus main body 2 can move up and down, and is rotatably provided around the center axis line (parallel to the Z axis) by a base drive source (not shown).

The nozzle means 72 mixes the air supplied from the air supply source which is not shown to liquid resin J containing water-soluble resins, such as PVA, PEG, and PEO (polyethylene oxide). And the nozzle means 72 blows off the liquid resin J mixed with air toward the surface WS of the wafer W before the laser processing hold | maintained by the holding table 71 in the fog form from above. The nozzle means 72 is equipped with the nozzle 73 which injects the liquid resin J in which air was mixed. The plurality of nozzles 73 are arranged in parallel with the radial direction of the wafer W held by the holding table 71. In addition, the nozzle means 72 moves the upper direction of the holding table 71 to a horizontal direction by the horizontal direction moving means which is not shown in figure. The cleaning nozzle ejects the washing water toward the surface WS of the wafer W after the laser processing held by the holding table 71 to remove the protective film P. As shown in FIG. In addition, the above-mentioned liquid resin J which comprises the protective film P and the protective film P is transparent and translucent, and permeate | transmits light.

Moreover, the protective film P is coat | covered with the nozzle means 72, and the wafer W before laser processing is arrange | positioned on the chuck table 10 by the 2nd conveyance means 82. As shown in FIG. In addition, the protective film P is removed by the cleaning nozzle of the wafer W after laser processing, and is arrange | positioned on the rail 62 of the provisional placement means 60 by the 1st conveyance means 81.

The laser beam irradiation means 20 irradiates a laser beam to the surface WS of the wafer W from the protective film P side, and the laser processing groove S to the wafer W held by the chuck table 10. To form. The laser beam irradiation means 20 is provided so as to be movable in the Y-axis direction by the Y-axis moving means with respect to the wafer W held by the chuck table 10, and in the Z-axis direction by the Z-axis moving means. It is provided to be movable. The laser beam irradiation means 20 comprises a laser beam oscillation means (not shown) and a condenser (not shown) for irradiating the surface WS of the wafer W to the laser beam oscillated by the laser beam oscillation means. have. The laser beam oscillation means can be suitably selected according to the kind, processing form, etc. of the wafer W, and a YAG laser oscillator, a YVO laser oscillator, etc. can be used, for example. The condenser includes a total reflection mirror for changing the traveling direction of the laser beam oscillated by the laser beam oscillation means, a condenser lens for condensing the laser beam, and the like.

The imaging means 30 picks up the image surface WS of the wafer W held by the chuck table 10. The imaging means 30 is provided so that the wafer W held by the chuck table 10 can be moved in the Y axis direction integrally with the laser beam irradiation means 20 by the Y axis moving means, and the Z axis The moving means is provided so as to be movable in the Z-axis direction integrally with the laser beam irradiation means 20. The imaging means 30 is equipped with the CCD camera which is not shown in figure. The CCD camera captures a part of the outer circumferential edge E of the wafer W held on the chuck table 10 and a part of the holding surface 11a of the chuck table 10 so as to capture an image G (FIG. 10). Is shown). The imaging means 30 outputs the information of the image G obtained by the CCD camera to the control means 40.

In the chuck table 10, the wafer W before the laser processing in which the protective film P is formed is disposed by the second transfer means 82 to hold the wafer W. As shown in FIG. 2 and 3, the chuck table 10 sucks the holding member 11 which has the holding surface 11a on the upper surface which hold | maintains the wafer W via the adhesive tape T, and suctions it. A suction path 13 (shown in FIG. 3) communicating with the circle 12 (shown in FIG. 3), the LED 14 as a light emitting body provided below the holding member 11, the holding member 11, and the LEDs. Table frame 15 with 14 is provided.

As shown in Figs. 2 and 3, the holding member 11 has a disk-shaped suction region 16 formed of a porous ceramic or the like on the surface 16a, and a light transmitting region that covers the suction region 16 ( 17) is configured to include. In the suction region 16, the wafer W is disposed on the surface 16a, connected to the suction source 12 via the suction path 13, and sucks the wafer W disposed on the surface 16a. The suction is maintained by the negative pressure from the furnace 13. The light transmissive region 17 is made of a transparent or translucent member that can transmit light, has an outer diameter larger than the diameter of the wafer W, and has an inner diameter smaller than the diameter of the wafer W (annular shape). It is formed. In this embodiment, the transparent or translucent member which can permeate | transmit the light which comprises the light transmission area | region 17 is a material which has transparency and dispersibility with respect to the wavelength of the laser beam which the laser beam irradiation means 20 irradiates. In the light transmission region 17, the outer peripheral edge E of the wafer W is disposed on the surface 17a. The surface 16a of the suction region 16 and the surface 17a of the light transmitting region 17 are provided on the same plane, and constitute the holding surface 11a of the holding member 11.

The suction path 13 connected to the suction area 16 of the holding member 11 is a passage formed in the table frame 15, the table moving base 3, and the like. The LED 14 is provided below the light transmitting region 17 of the holding member 11. The LED 14 emits light to brighten the light transmitting region 17.

On the other hand, the chuck table 10 is detachable to the table moving base 3 provided with the table frame 15 in the apparatus main body 2. On the other hand, the table moving base 3 is provided to be movable in the X-axis direction by the X-axis moving means, and is provided rotatably around the center axis line (parallel to the Z-axis) by a base driving source (not shown). Moreover, the clamp part 18 is provided in the circumference | surroundings of the chuck table 10, and the annular frame F of the circumference | surroundings of the wafer W is clamped by the clamp part 18 being driven by the air actuator not shown. do.

Here, the wafer W is a process target which is laser-processed by the laser processing apparatus 1, and is a disk-shaped semiconductor wafer or an optical device wafer which uses silicon, sapphire, gallium, etc. as a base material in this embodiment. As shown in FIGS. 5A and 5B, the wafer W is disposed on the first and second streets W1 and W2 as a plurality of devices D on the surface WS as the dividing lines. It is partitioned by. On the other hand, the 1st street W1 and the 2nd street W2 are each provided in multiple numbers, and are mutually crossing (orthogonal in this embodiment). For this reason, the device D is formed in the area | region partitioned by the 1st and 2nd streets W1 and W2 of the surface WS. As shown in FIGS. 5A and 5B, the wafer W is adhered to the adhesive tape T by the back surface on the opposite side of the surface WS on which the plurality of devices D are formed. The annular frame F is affixed to the adhesive tape T adhered to (W), so that the annular frame F is fixed. On the surface WS of the wafer W, a so-called low-k film (not shown) made of a low-k material (mainly a porous material) is formed as an interlayer insulating film material. On the other hand, the adhesive tape T is transparent or translucent and transmits light.

The control means 40 controls each of the above-mentioned components which comprise the laser processing apparatus 1 and the chuck table 10, respectively. The control means 40 causes the laser processing apparatus 1 to perform the machining operation with respect to the wafer W. As shown in FIG. In addition, when the control means 40 makes the laser processing apparatus 1 perform the machining operation with respect to the wafer W, the imaging means 30 image | photographs a part of outer peripheral edge E of the wafer W. As shown in FIG. The position on the chuck table 10 of the entire outer peripheral edge E of the wafer W is also detected from the obtained image G. On the other hand, the control means 40 mainly consists of an arithmetic processing apparatus comprised of a CPU, etc., or a microprocessor (not shown) provided with ROM, RAM, etc., and the display means 83 which displays the state of a machining operation. In addition, it is connected with the operation means which is not shown in figure which an operator uses when registering processing content information.

Next, the laser processing method of the wafer W using the laser processing apparatus 1, ie, the chuck table 10, which concerns on this embodiment is demonstrated. First, in step ST1 in FIG. 4, as shown in FIG. 5A, the surface WS on which the device D is formed is taken as an upper surface, and as shown in FIG. 5B, the wafer. (W) is adhered to the annular frame F via the adhesive tape T. And the wafer W adhering to the annular frame F through the adhesive tape T is accommodated in the cassette elevator 50. As shown in FIG. On the other hand, step ST1 is a wafer adhesion step.

The process proceeds to step ST2, where the operator registers the processing content information in the control means 40, and the laser processing apparatus 1 starts the processing operation when the operator has instructed to start the processing operation. In the machining operation, the control means 40 carries out the wafer W before the laser processing from the cassette elevator 50 to the temporary distributing means 60 by the carrying in / out means 61, and thus, of the temporary distributing means 60. After arrange | positioning on a pair of rail 62, it conveys to the holding table 71 of the protective film formation and the washing | cleaning means 70 by the 1st conveying means 81, and is hold | maintained by the holding table 71. FIG. And after the control means 40 lowers the holding table 71, the liquid resin J mixed with air from the nozzle 73 is ejected from the nozzle means 72, as shown in FIG. The upper portion of the wafer W held by the holding table 71 is moved. Then, the liquid resin (J) is ejected in a fog form from the nozzle (73) toward the surface (WS) of the lower wafer (W), and the liquid resin (J) adhered to the surface (WS) of the wafer (W) By hardening, the protective film P comprised of the liquid resin J is coat | covered on the surface WS of the wafer W. As shown in FIG. Thus, in step ST2, after performing step ST1, the liquid resin J is apply | coated to the surface WS of the wafer W, and the protective film P is formed. On the other hand, step ST2 is a protective film coating step. When the coating of the protective film P is finished, the control means 40 raises the holding table 71 and removes the wafer W coated with the protective film P from the holding table 71 to the chuck table 10. It conveys to the 2 conveying means 82, is hold | maintained by the chuck table 10, as shown in FIG. 7, and it progresses to step ST3.

Next, the control means 40 moves the chuck table 10 by the X-axis moving means, and as shown in FIGS. 8 and 9, the outer side of the wafer W held by the chuck table 10. A part of the circumferential edge E and a part of the chuck table 10 are positioned below the imaging means 30. Then, the control means 40 emits the LED 14 of the chuck table 10, and a part of the outer peripheral edge E of the wafer W and a part of the chuck table 10 by the imaging means 30. To capture the image. In this way, the wafer W does not transmit light from the LED 14, the light transmitting region 17 and the protective film P transmit the light from the LED 14, and the light transmitting region 17 The inner and outer diameters are formed in the above-described dimensions, so that the outer peripheral edge E of the wafer W is positioned on the light transmitting region 17 of the chuck table 10. For this reason, in the image G obtained by the imaging means 30, as shown in FIG. 10, the luminance value of the light of the part B1 (shown black in FIG. 10) which shows the wafer W is very low, and light The brightness | luminance value of the light of the part B2 (shown white in FIG. 10) which shows the transmission area | region 17 is very high.

And the control means 40 is the image G with a very large difference (contrast) of the brightness value of the light of the part B1 which shows the wafer W, and the part B2 which shows the light transmission area | region 17. From this, the outer peripheral edge E of the wafer W is detected (extracted). And the control means 40 selects at least arbitrary 3 points in the outer periphery edge E of the wafer W, and selects the wafer (in the chuck table 10) from the coordinates (position) of the selected 3 points ( The coordinate of the center of W), that is, the center position is calculated. The control means 40 is a position of the whole outer peripheral edge E of the wafer W on the chuck table 10 from the center position etc. (the chuck table of the whole outer peripheral edge E of the wafer W). Relative position relative to (10).

Thus, in step ST3, after performing step ST2, the outer peripheral edge E of the wafer W is positioned on the light transmitting region 17 of the chuck table 10, and the LEDs 14 emit light. The wafer W is imaged. And in step ST3, the wafer W arrange | positioned at the chuck table 10 via the adhesive tape T is imaged using the imaging means 30, and the outer periphery edge E of the wafer W is carried out. Detect all. On the other hand, step ST3 is an outer peripheral edge detection step. When the detection of the outer peripheral edge E of the wafer W is completed, the process proceeds to step ST4.

Next, the control means 40 moves the chuck table 10 by the X-axis moving means based on the position of the entire outer circumferential edge E of the wafer W detected in step ST3, and the like, and the base drive source. Rotates the chuck table 10 around the central axis, and moves the laser beam irradiation means 20 by the Y-axis moving means and the Z-axis moving means to move one end of the predetermined streets W1 and W2 to the condenser. Position it just below. The control means 40 carries out the predetermined distance W1, W2 from the chuck table 10 which hold | maintained the wafer W by the X-axis movement means, irradiating a laser beam from the condenser of the laser beam irradiation means 20. FIG. Therefore, it moves at a predetermined processing speed.

As a result, a portion of the wafer W and the protective film P are sublimated on the predetermined streets W1 and W2 to which the laser beam is irradiated, and as shown in FIG. 11, the laser processing grooves S are formed. . When the other ends of the predetermined streets W1 and W2 reach just below the condenser, the irradiation of the laser beam from the laser beam irradiation means 20 is stopped and the movement of the chuck table 10, that is, the wafer W, is stopped. do. As described above, the control means 40 irradiates the laser beams to the streets W1 and W2 in order to form the laser processing grooves S in these streets W1 and W2, and the Laser processing grooves S are formed in all the streets W1 and W2. As described above, in step ST4, after performing step ST3, the laser beam is irradiated onto the surface WS of the wafer W from the side of the protective film P along the streets W1 and W2 of the wafer W, and the wafer ( The laser processing groove S is formed in W). On the other hand, step ST4 forms a laser processing groove forming step.

When the laser processing grooves S are formed in all the streets W1 and W2, the control means 40 moves the chuck table 10 to the vicinity of the protective film formation and cleaning means 70 by the X-axis driving means. The wafer W subjected to laser processing on the chuck table 10 is disposed on the holding table 71 of the protective film forming and cleaning means 70 by the second transfer means 82, and placed on the holding table 71. Keep it. After the holding means 71 is lowered, the control means 40 ejects the washing water from the cleaning nozzle to the wafer W on the holding table 71 while rotating the holding table 71 around the center axis. Let's do it. In this case, since the protective film P is made of water-soluble resin, the protective film P is removed from the surface WS of the wafer W together with the debris attached at the time of laser processing by washing water and centrifugal force. (Washed down). When removal of the protective film P is complete | finished, the control means 40 raises the holding table 71 after stopping rotation of the rotation around the central axis of the holding table 71, and ejection of the washing water from a washing | cleaning nozzle. 1st conveyance means 81 conveys to provisional placement means 60. The control means 40 carries in the cassette elevator 50 from the provisional placement means 60 by the carrying-out means 61 by the carrying-out means 61 by laser processing etc.

As described above, according to the laser processing method using the chuck table 10 and the chuck table 10 according to the present embodiment, the portion where the outer peripheral edge E of the wafer W is positioned (arranged) is provided. The light transmitting region 17 is formed to transmit light of the LED 14, and the LED 14 emits light at the time of imaging. Thus, the wafer W is darkly reflected on the imaging means 30, and the light transmitting region 17 is formed. The pressure-sensitive adhesive tape T on the wafer W on () is lightened (brightly) by the influence of the light from the LED 14. Thus, in this embodiment, the contrast of the part B1 which shows the wafer W and the part B2 which shows the light transmission area | region 17 becomes clear than a comparative example (shown in FIG. 12), and is close to transparency. It is possible to obtain an image G in which the droplets of the liquid resin J and the bubbles B (shown in broken lines in FIG. 10) are almost invisible. Therefore, the position of the outer circumferential edge E of the wafer W can be detected without being affected by droplets or bubbles B, and the position of the entire outer circumferential edge E of the wafer W can be detected. It can be detected without errors.

On the other hand, the comparative example shown in FIG. 12 is the image Ga obtained by image | photographing the wafer W etc. which were hold | maintained on the conventional chuck table in which the light transmission area | region 17 and the LED 14 are not provided. In the comparative example, since the light transmitting region 17 and the LED 14 are not provided, the luminance value of the light of the portion B1 showing the wafer W and the holding surface 11a of the chuck table 10 are shown. The difference in the luminance value of the light in the portion B2 is much smaller than the embodiment shown in FIG. 10, so that the luminance value of the light in the portion showing the droplet and bubble B is the portion of the portion B1 showing the wafer W. The value is close to both the luminance value of the light and the luminance value of the light of the portion B2 showing the holding surface 11a of the chuck table 10.

Moreover, since the suction area | region 16 other than the light transmission area | region 17 of the chuck table 10 is formed with the porous ceramic etc. which are normally used, the clamp part 18 provided in the outer periphery of the chuck table 10 is carried out. In this case, sufficient fixing of the wafer W can be realized without providing an adsorption mechanism to the light transmitting region 17. Therefore, special processing such as forming a groove for suction, for example, is performed. There is no need to do it. For this reason, the shape of the suction groove is not reflected in the retained wafer W, which is formed when the groove for suction is formed, so that adverse effects on laser processing and the like can be suppressed.

Moreover, the material which has transparency and dispersibility with respect to the wavelength of a laser beam is used for the transparent or translucent member which comprises the light transmission area | region 17. As shown in FIG. For this reason, even if a laser beam is irradiated to the position deviating from the outer peripheral edge E of the wafer W, the holding surface 11a can be prevented from being damaged or melted by a laser beam.

In the above-mentioned embodiment, although the protective film P is once covered and laser processing is performed, this invention is not limited to this, It is not necessary to necessarily coat the protective film P once. In addition, in this embodiment, after performing the binarization process on the image G obtained by the imaging means 30 by a predetermined threshold value, you may make it detect (extract) the outer peripheral edge E. FIG.

The present invention is not limited to the above-described embodiments. That is, it can be carried out in a variety of modifications within the scope not to deviate from the bones of the present invention. That is, the holding means, the rotating means, and the magnetic field changing means may be various configurations and arrangements, without being limited to the configurations and arrangements described in the embodiments.

10: chuck table 11: retaining member
11a: holding surface 12: suction source
13: suction path 14: LED (light emitting body)
16: suction area 17: light transmitting area
30: imaging means D: device
E: outer peripheral edge F: annular frame
J: liquid resin (protective material) P: protective film
S: Laser groove T: Adhesive tape
W: Wafer W1: First Street (Division Line)
W2: Second Street (Segmented Line) WS: Surface
ST1: wafer adhesion step ST2: protective film coating step
ST3: Outer Perimeter Edge Detection Step ST4: Laser Processing Groove Formation Step

Claims (2)

A chuck table which adheres to an annular frame via an adhesive tape and holds a wafer in which a plurality of devices are partitioned on a surface thereof by a line to be divided, on a holding surface via the adhesive tape,
The chuck table includes a suction path communicating with a suction source, a holding member having the holding surface on an upper surface thereof, and a light emitting member provided below the holding member,
The holding member includes a suction region for suction holding and holding the wafer disposed by the negative pressure from the suction path, and a light transmitting region including a transparent or translucent member for the suction region,
The light emitter is provided below the light transmitting region,
The light transmitting region is a chuck table, characterized in that the outer diameter is larger than the diameter of the wafer and the inner diameter is smaller than the diameter of the wafer. A laser processing method of a wafer using the chuck table according to claim 1,
A wafer adhesion step of adhering the wafer to the annular frame with the adhesive tape interposed therebetween, with the surface where the device is formed in a region partitioned by a plurality of divisional lines as an upper surface;
A protective film coating step of forming a protective film by applying a protective material to the surface of the wafer after performing the wafer sticking step;
An outer peripheral edge detection step of detecting an outer peripheral edge of the wafer by imaging the wafer placed on the chuck table via the adhesive tape after the protective film coating step;
A laser processing groove forming step of forming a laser processing groove on the wafer by irradiating a laser beam on the surface of the wafer from the passivation film side along the dividing line of the wafer after performing the outer peripheral edge detection step;
Lt; / RTI >
In the outer circumferential edge detection step, the outer circumferential edge of the wafer is positioned on the light transmitting area of the chuck table, and the light emitter emits light to image the wafer. Processing method.

Images