Processing method

Abstract

To provide a processing method capable of extracting a small piece in which a curve is formed on a contour from a workpiece without damaging the small piece.SOLUTION: A processing method forms a small piece having a predetermined contour from a workpiece including a first face and a second face which is a back of the first face. The processing method includes: a first support member arrangement step 101 of arranging a base material of a tape on the first face of the workpiece via a paste layer of the tape; a processing step 102 of dividing the workpiece along the contour to form the small piece which is defined by the contour and an end material in a region excluding the small piece after the first support member arrangement step 101 is implemented; and a removal step 104 of removing the small piece or the end material from the base material of the tape by decomposing the paste layer by irradiating any one of the paste layer of the tape in a region corresponding to the small piece or the paste layer of the tape in a region corresponding to the end material with a laser beam after the processing step 102 is implemented.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a processing method for forming pieces having a predetermined contour from a workpiece. [Background technology]

[0002] Semiconductor device chips are generally rectangular, and the wafer has a grid of dividing lines formed on it. Such wafers are divided while attached to tape, and after division, the tape is expanded to create spaces between adjacent chips so that chips can be picked up from the tape, preventing them from coming into contact with and being damaged by adjacent chips during pick-up.

[0003] On the other hand, there are cases where the planned dividing lines are not grid-shaped, but chips are cut out from the wafer along the chip contour, and a laser processing device suitable for irradiating a laser beam onto a wafer along the chip contour having straight and curved portions has been disclosed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-062289 Summary of the Invention [Problem to be solved by the invention]

[0005] As shown in Patent Document 1, in a workpiece that is a wafer having a plurality of small pieces, which are chips having straight and curved lines, after cutting along the contours of the small pieces, there is a risk that the small pieces will come into contact with the surrounding scrap material and be damaged when removing them from the workpiece, making it difficult to remove the small pieces. This problem is particularly pronounced when the small pieces are small or have complex shapes.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide a processing method that can remove small pieces having a curved contour from a workpiece without damaging them. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the processing method of the present invention is a processing method for forming small pieces having a predetermined outline from a workpiece including a first surface and a second surface behind the first surface, and is characterized by comprising: a first support member arranging step for arranging a first support member on the first surface of the workpiece via an adhesive layer; a processing step for dividing the workpiece along the outline after performing the first support member arranging step to form the small pieces defined by the outline and scrap material in the area excluding the small pieces; and a removal step for irradiating electromagnetic waves to either the adhesive layer in the area corresponding to the small pieces or the adhesive layer in the area corresponding to the scrap material after performing the processing step to alter the adhesive layer and remove the small pieces or the scrap material from the first support member.

[0008] In the above processing method, the electromagnetic wave may be a laser beam.

[0009] In the processing method, the processing step includes irradiating a laser beam onto the workpiece along the contour, and the laser beam irradiated onto either the adhesive layer in the area corresponding to the small piece or the adhesive layer in the area corresponding to the scrap material in the removal step and the laser beam irradiated onto the workpiece in the processing step may be generated by the same oscillator.

[0010] In the processing method, after performing the processing step and before performing the removing step, a second support member disposing step may be provided in which a second support member is disposed on the second surface of the workpiece, and in the removing step, the small pieces or scrap material may be transferred to the second support member.

[0011] In the above processing method, in the removing step, the electromagnetic waves may be irradiated onto the adhesive layer in a region corresponding to the smaller of the small piece and the scrap.

[0012] In the processing method, the contour may include a curve. [Effects of the Invention]

[0013] The present invention has the advantage that small pieces having curved contours can be removed from a workpiece without being damaged. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view showing an example of the structure of a workpiece to be processed by the processing method according to the first embodiment. [Figure 2] FIG. 2 is a flowchart showing the flow of the processing method according to the first embodiment. [Figure 3] FIG. 3 is a perspective view showing the workpiece after the first support member disposing step of the processing method shown in FIG. [Figure 4] FIG. 4 is a side view, partly in section, schematically showing the processing steps of the processing method shown in FIG. [Figure 5] FIG. 5 is a plan view showing the workpiece after the processing step of the processing method shown in FIG. [Figure 6] FIG. 6 is a cross-sectional view showing the workpiece after the second support member disposing step of the processing method shown in FIG. [Figure 7] FIG. 7 is a side view, partly in section, schematically showing the removing step of the processing method shown in FIG. [Figure 8] FIG. 8 is a plan view showing the small pieces etc. after the removing step of the processing method shown in FIG. [Figure 9] FIG. 9 is a plan view showing the offcuts and the like after the removing step of the processing method shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] Modes (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that can be easily imagined by a person skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the configuration can be made within the scope of the gist of the present invention.

[0016] [Embodiment 1] A processing method according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view showing an example of the structure of a workpiece to be processed by the processing method according to the first embodiment. Fig. 2 is a flowchart showing the flow of the processing method according to the first embodiment.

[0017] (workpiece) The processing method according to the first embodiment is a method for processing a workpiece 1 shown in Fig. 1. The workpiece 1 to be processed by the processing method according to the first embodiment is, as shown in Fig. 1, a wafer such as a disk-shaped semiconductor wafer or an optical device wafer, with a substrate 2 made of silicon, sapphire, gallium, SiC, or the like. In the first embodiment, the workpiece 1 is a semiconductor wafer with a substrate 2 made of silicon.

[0018] As shown in FIG. 1 , the workpiece 1 is formed in a disk shape, including a circular first surface 3 and a circular second surface 4 that is on the back side of the first surface 3 and parallel to the first surface 3. In the first embodiment, the workpiece 1 has a predetermined position where a small piece 6 having a predetermined outline 5 (shown by a dashed line in FIG. 1 ) is to be formed. Note that the outline 5 is an imaginary line set on the first surface 3 and is not actually formed on the first surface 3. However, in the present invention, the outline 5 is not limited to an imaginary line and may be a recessed groove, a protruding portion, a drawn line, or the like extending from the first surface 3. In the first embodiment, the outline 5 is formed in a circular shape, and the small piece 6 formed by the outline 5 is formed in a disk shape.

[0019] In the present invention, the contour 5 of the small piece 6 is not limited to a circle as long as it includes at least a curved line. That is, in the present invention, the contour 5 of the small piece 6 may include only curved lines, or may include curved lines and straight lines.

[0020] In the present invention, the workpiece 1 may have a device formed on each small piece formed by the contour 5. Alternatively, the workpiece 1 may have a plurality of mutually intersecting division lines formed on the first surface 3, and a device may be formed in each of the regions partitioned in a grid pattern by the division lines. The device may be, for example, an integrated circuit such as an IC (Integrated Circuit) or an LSI (Large Scale Integration), or a memory (semiconductor memory device).

[0021] Furthermore, in the present invention, the substrate 2 of the workpiece 1 is not limited to being made of silicon or the like, but may be made of glass or ceramics, for example.

[0022] (Processing method) Next, a processing method according to embodiment 1 will be described. The processing method according to embodiment 1 is a method of forming a plurality of small pieces 6 by extracting a plurality of small pieces 6 having a predetermined contour 5 from a workpiece 1 shown in Fig. 1. As shown in Fig. 2, the processing method according to embodiment 1 includes a first support member providing step 101, a processing step 102, a second support member providing step 103, and a removal step 104.

[0023] (First support member disposing step) Fig. 3 is a perspective view showing the workpiece after the first support member providing step of the processing method shown in Fig. 2. The first support member providing step 101 is a step of providing a first support member on the first surface 3 of the workpiece 1 via an adhesive layer. In the first embodiment, in the first support member providing step 101, as shown in Fig. 3, the center of a disk-shaped tape 10 having a diameter larger than the outer diameter of the workpiece 1 is adhered to the first surface 3 of the workpiece 1, and an annular frame 11 having an inner diameter larger than the outer diameter of the workpiece 1 is adhered to the outer edge of the tape 10.

[0024] The tape 10 includes a substrate made of a non-adhesive synthetic resin and a glue layer made of an adhesive synthetic resin laminated on the substrate, with the substrate corresponding to the first support member and the glue layer corresponding to the adhesive layer. In the present invention, the outer diameter of the tape 10 may be formed to be equal to the outer diameter of the workpiece 1, and the frame 11 may not be attached to the outer edge of the tape 10. In the present invention, the first surface 3 of the workpiece 1 may be disposed via an adhesive layer on a hard plate made of glass, silicon, or the like as the first support member.

[0025] (Processing step) Fig. 4 is a side view, partially in cross section, schematically showing the processing steps of the processing method shown in Fig. 2. Fig. 5 is a plan view showing the workpiece after the processing steps of the processing method shown in Fig. 2. Processing step 102 is a step in which, after performing first support member arrangement step 101, workpiece 1 is divided along contour 5 to form small pieces 6 defined by contour 5 and scrap material 7 in the area excluding small pieces 6.

[0026] In the first embodiment, in the processing step 102, the laser processing device 20 shown in Fig. 4 suction-holds the first surface 3 of the workpiece 1 to the holding surface 22 of the holding table 21 via the base material of the tape 10, and clamps the frame 11 with the clamp section 23 provided around the holding table 21. In the first embodiment, in the processing step 102, the laser processing device 20 captures an image of the workpiece 1 with an imaging camera, and performs alignment to align the workpiece 1 with the focusing lens 25, which is a collector of the laser beam irradiation unit 24.

[0027] In the first embodiment, in the processing step 102, the laser processing device 20 relatively moves the holding table 21 and the laser beam irradiation unit 24 along the predetermined contour 5 of the small pieces 6, as shown in FIG. 4, while setting the focal point of a pulsed laser beam 27 oscillated by the oscillator 26 and having a wavelength absorbable by the workpiece 1 and the tape 10 on the second surface 4 of the workpiece 1, and irradiates the laser beam toward the second surface 4 of the workpiece 1 to form division grooves 12 (shown in FIG. 5) that divide the workpiece 1 along the contour 5 by ablation. Thus, in the first embodiment, in the processing step 102, the laser beam 27 is irradiated onto the workpiece 1 along the contour 5 to form division grooves 12 along the contour 5 in the workpiece 1, and as shown in FIG. 5, the workpiece 1 is divided into a plurality of small pieces 6 and a scrap 7 excluding the small pieces 6. In the first embodiment, the wavelength of the laser beam 27 is a wavelength absorbable by silicon, for example, 355 nm.

[0028] In the present invention, if it is difficult to form the dividing grooves 12 that divide the workpiece 1 with a single laser beam 27, the dividing grooves 12 are formed by changing the position of the focal point in the thickness direction of the workpiece 1 and irradiating the laser beam 27 multiple times. Also, in the present invention, when irradiating the laser beam 27 to perform ablation processing, a protective film may be applied to the second surface 4 side, and the protective film may be removed after the dividing grooves 12 are formed.

[0029] Furthermore, in the present invention, the dividing grooves 12 may be formed in the workpiece 1 by plasma etching or cutting with a cutting blade, without irradiating the workpiece 1 with the laser beam 27. The dividing grooves 12 may be formed by irradiating the workpiece 1 with the laser beam 27, and may be composed of a plurality of pores that penetrate the workpiece 1 and are arranged along the contour 5, and cracks that connect the pores.

[0030] (Second support member disposing step) Fig. 6 is a cross-sectional view showing the workpiece after the second support member providing step of the processing method shown in Fig. 2. The second support member providing step 103 is a step of providing a second support member 13 on the second surface 4 of the workpiece 1 after the processing step 102 is performed and before the removal step 104 is performed.

[0031] In the first embodiment, in the second support member disposing step 103, as shown in Fig. 6, the center of a disk-shaped second support member 13 having a diameter larger than that of the workpiece 1 is adhered to the second surface 4 of the workpiece 1, and the outer edge of the second support member 13 is adhered to the frame 11. In the first embodiment, in the second support member disposing step 103, for example, a tape or sheet having a base material and an adhesive layer similar to the tape 10 is used as the second support member 13.

[0032] The tape used as the second support member 13 preferably has an adhesive layer with lower adhesive strength than the adhesive layer of the tape 10. The sheet used as the second support member 13 is preferably a sheet with no adhesive layer and with tack (such as "Flex Carrier (registered trademark)" manufactured by UMI Co., Ltd. or "Gel Base (registered trademark)" manufactured by Exseal Corporation).

[0033] (Removal step) Fig. 7 is a side view, partially in cross section, schematically showing the removal step of the processing method shown in Fig. 2. Fig. 8 is a plan view showing small pieces, etc., after the removal step of the processing method shown in Fig. 2. Fig. 9 is a plan view showing scraps, etc., after the removal step of the processing method shown in Fig. 2. The removal step 104 is a step in which, after processing step 102 has been performed, a laser beam 27, which is an electromagnetic wave, is irradiated onto either the adhesive layer of the tape 10 in the area corresponding to the small pieces 6 or the adhesive layer of the tape 10 in the area corresponding to the scraps 7, thereby altering the adhesive layer of the tape 10 and removing the small pieces 6 or scraps 7 from the tape 10.

[0034] In the first embodiment, in the removal step 104, the laser processing device 20 shown in Fig. 7 suction-holds the second surface 4 of the workpiece 1 to the holding surface 22 of the holding table 21 via the second support member 13, and clamps the frame 11 with the clamp section 23 provided around the holding table 21. In the first embodiment, in the removal step 104, the laser processing device 20 images the workpiece 1 with the imaging camera, and performs alignment to align the workpiece 1 with the focusing lens 25, which is a collector of the laser beam irradiation unit 24.

[0035] In the first embodiment, in the removal step 104, as shown in Fig. 7, the laser processing device 20 sets the focal point of a pulsed laser beam 27 oscillated by the oscillator 26 and having a wavelength absorbable by the workpiece 1 and the tape 10 at a location other than the adhesive layer of the tape 10 while relatively moving the holding table 21 and the laser beam irradiation unit 24, and irradiates the laser beam toward the first surface 3 of the workpiece 1 to irradiate the area of ​​the adhesive layer of the tape 10 attached to the scrap 7. In the first embodiment, in the removal step 104, the focal point of the laser beam 27 is set at a location other than the adhesive layer of the tape 10 and defocused with respect to the adhesive layer of the tape 10, so that the beam spot on the tape 10 (the area on the first surface 3 irradiated with the laser beam 27) is formed larger than the beam spot on the first surface 3 of the workpiece 1 in the processing step 102, and the laser beam 27 is irradiated with an energy intensity of the laser beam 27 not exceeding the processing threshold of the workpiece 1.

[0036] In the first embodiment, the wavelength (355 nm) of the laser beam 27 in the removing step 104 is not transparent to silicon, which is the workpiece 1. Furthermore, if the focal point of the laser beam 27 is positioned closer to the holding table 21 than the workpiece 1, there is a risk that the reflected light of the laser beam 27 from the first surface 3 of the workpiece 1 will be focused on the focusing lens 25, depending on the focal length of the focusing lens 25 and the refractive index of the workpiece 1. Therefore, it is preferable to position the focal point of the laser beam 27 inside the workpiece 1 or closer to the focusing lens 25 than the adhesive layer of the tape 10. Furthermore, in the present invention, in the removing step 104, the laser beam 27 may be irradiated with the focal point positioned close to just focus depending on the irradiation area.

[0037] In embodiment 1, in the removal step 104, the laser processing device 20 alters the area of ​​the adhesive layer of the tape 10 that is adhered to the scrap 7, thereby reducing the adhesive strength of the area of ​​the adhesive layer of the tape 10 that is adhered to the scrap 7 below the adhesive strength of the second support member 13. Thus, in the present invention, the electromagnetic wave irradiated to the workpiece 1 in the removal step 104 is a laser beam 27. Also, in the present invention, the laser beam 27 irradiated to either the adhesive layer in the area corresponding to the small piece 6 of the tape 10 (the area of ​​the adhesive layer that is adhered to the small piece 6 of the adhesive layer) or the adhesive layer in the area corresponding to the scrap 7 of the tape 10 (the area of ​​the adhesive layer that is adhered to the scrap 7 of the adhesive layer) in the removal step 104, and the laser beam 27 irradiated to the workpiece 1 in the processing step 102 are laser beams generated by the same oscillator 26.

[0038] In the present invention, the output of the irradiated laser beam 27 in the removing step 104 may be set lower than that in the processing step 102 so as not to exceed the processing threshold value of the workpiece 1 .

[0039] In embodiment 1, in the removal step 104, when defocusing the focal point of the laser beam 27 on the adhesive layer of the tape 10, the focal point may be set closer to the oscillator 26 than the tape 10, or closer to the holding surface 22 of the holding table 21. In embodiment 1, in the removal step 104, the laser processing device 20 defocuses the focal point of the laser beam 27 on the adhesive layer of the tape 10, and irradiates the laser beam 27 onto the entire area of ​​the adhesive layer of the tape 10 that is adhered to the scrap material 7, thereby altering the area of ​​the adhesive layer of the tape 10 that is adhered to the scrap material 7 and reducing the adhesive strength below that of the second support member 13.

[0040] In removal step 104, second support member 13 is peeled off from frame 11. Then, the adhesive strength of the area of ​​the adhesive layer of tape 10 that is attached to scrap material 7 is lower than the adhesive strength of second support member 13, so scrap material 7 is removed from tape 10, leaving small pieces 6 attached to tape 10, as shown in Figure 8, and scrap material 7 remains attached to second support member 13, as shown in Figure 9.

[0041] In embodiment 1, in the removal step 104, when the tape 10 and the second support member 13 are attached to the front and back surfaces of the frame 11, the small pieces 6 are left on the tape 10 attached to the frame 11, so that the frame 11 is normally oriented in the device for the subsequent pickup process that picks up the small pieces 6, making alignment easier.

[0042] Furthermore, in the present invention, in the removal step 104, the laser processing device 20 may defocus the focal point of the laser beam 27 on the adhesive layer of the tape 10 and irradiate the laser beam 27 onto the entire area of ​​the adhesive layer of the tape 10 that is adhered to the small pieces 6, thereby altering the area of ​​the adhesive layer of the tape 10 that is adhered to the small pieces 6 and reducing the adhesive strength below that of the second support member 13. In this case, when the second support member 13 is peeled off from the frame 11, the adhesive strength of the area of ​​the adhesive layer of the tape 10 that is adhered to the small pieces 6 is reduced below that of the second support member 13, so that the small pieces 6 are removed from the tape 10, leaving the scrap material 7 adhered to the tape 10, and the small pieces 6 remaining adhered to the second support member 13.

[0043] As described above, in the present invention, it is desirable to irradiate the laser beam 27, which is an electromagnetic wave, onto the adhesive layer of the tape 10 in an area corresponding to the smaller of the small pieces 6 and the scrap 7 (for example, the small pieces 6) (the area of ​​the adhesive layer attached to the smaller of the small pieces 6 and the scrap 7). In this case, by irradiating a large area with the laser beam 27 in the removal step 104, it is possible to shorten the time required for the removal step 104. Thus, in the removal step 104, the small pieces 6 or the scrap 7 are transferred from the tape 10 to the second support member 13, and the small pieces 6 and the scrap 7 are separated.

[0044] As described above, the processing method of embodiment 1 involves arranging the workpiece 1 on the base material of the tape 10, which is the first support member, via an adhesive layer in the first support member arrangement step 101, processing the workpiece 1 arranged on the tape 10 to divide the workpiece 1 into small pieces 6 and scraps 7 in the processing step 102, and then irradiating the adhesive layer in the area of ​​the tape 10 corresponding to (attached to) the small pieces 6 or scraps 7 with a laser beam 27 to alter the adhesive layer and reduce the adhesive strength, thereby removing the small pieces 6 or scraps 7 from the tape 10 in the removal step 104.

[0045] In this way, the processing method of embodiment 1 makes it easy to selectively remove small pieces 6 or scraps 7 from the tape 10, thereby achieving the effect of allowing small pieces 6 having a curved contour 5 to be removed from the workpiece 1 without damaging them.

[0046] The present invention is not limited to the above-described embodiment. In other words, various modifications can be made without departing from the gist of the present invention. In the present invention, in the removal step 104, the light irradiated onto the adhesive layer piece 6 of the tape 10 or the area attached to the scrap 7 may be light from an LED (Light Emitting Diode) light source or a mercury lamp, in addition to the laser beam 27. [Explanation of symbols]

[0047] 1 Workpiece 3 Front page 4 Side 2 5. Contour 6 pieces 7 Scraps 26 Oscillator 27 Laser beam (electromagnetic wave) 101 First support member disposing step 102 Processing Steps 103 Second support member disposing step 104 Removal Steps

Claims

1. A processing method for forming a piece having a predetermined contour from a workpiece including a first surface and a second surface behind the first surface, the method comprising: a first support member disposing step of disposing a first support member on the first surface of the workpiece via an adhesive layer; a processing step of dividing the workpiece along the contour after the first support member disposing step to form small pieces defined by the contour and scrap materials in areas other than the small pieces; After carrying out the processing step, the processing method includes a removal step in which electromagnetic waves are applied to either the adhesive layer in the area corresponding to the small piece or the adhesive layer in the area corresponding to the scrap material to alter the adhesive layer and remove the small piece or the scrap material from the first support member.

2. 2. The processing method according to claim 1, wherein the electromagnetic wave is a laser beam.

3. The processing step includes irradiating the workpiece with a laser beam along the contour; The processing method described in claim 2, wherein the laser beam irradiated to either the adhesive layer in the area corresponding to the small piece or the adhesive layer in the area corresponding to the scrap material in the removal step and the laser beam irradiated to the workpiece in the processing step are generated by the same oscillator.

4. a second support member disposing step of disposing a second support member on the second surface of the workpiece after performing the processing step and before performing the removing step; The processing method according to claim 1 , wherein the removing step comprises transferring the small pieces or the scrap material to the second support member.

5. The processing method according to claim 1 , wherein the removing step irradiates the electromagnetic waves to the adhesive layer in a region corresponding to the smaller of the small piece and the scrap.

6. The method of claim 3 , wherein the contour includes a curve.

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