Chip manufacturing method

Abstract

This invention provides a chip manufacturing method that can narrow the planned division lines while suppressing cracking during wafer thinning. [Solution] A chip manufacturing method for producing chips 11 by dividing a workpiece 1, which has a functional layer 13 formed on its surface 12a, along the division lines 15, wherein a plurality of division lines 15 are set on the surface 12a of the substrate 12, the method comprising: a laser processing groove forming step S1 in which a laser beam 21 is irradiated along the division lines 15 to remove the functional layer 13 and to form a processing groove 16 shallower than the finished thickness in the substrate 12; a thinning step S3 in which the back surface 12b of the substrate 12 is processed to thin the substrate 12 to the finished thickness; and a division step S6 in which an external force is applied to the workpiece 1 after the thinning step S3 to divide the workpiece 1 into a plurality of chips 11 along the processing groove 16.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing chips by dividing a workpiece along a planned division line to produce chips.

Background Art

[0002] When thinning a semiconductor wafer into chips, after thinning the wafer, a manufacturing method with a high yield is required so that the wafer does not crack when handling the thin wafer.

[0003] Therefore, Patent Document 1 describes the following manufacturing method. First, a division groove having a predetermined depth is formed along the planned division line from the surface of the wafer by a cutting blade, and then the surface of the wafer is covered with a protection member. Subsequently, the back surface of the wafer is polished to expose the division groove and divided into chips. Then, after uniformly attaching an adhesive film to the back surface of the wafer divided into chips, a laser beam is irradiated onto the adhesive film along the division groove to break the adhesive film.

[0004] According to this method, since the wafer is divided into chips when thinned, there is a possibility of cracking occurring in chip units, but cracking as a wafer does not occur.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in this method, in addition to the width of the cutting blade being required as the width of the division groove, there is a risk that chipping called chipping occurs on the surface. Therefore, it is difficult to meet the demand for narrowing the planned division line to increase the number of obtained device chips.

[0007] Therefore, in a chip manufacturing method that involves dividing a workpiece along a planned division line to produce chips, there is a challenge to provide a method that increases the number of device chips obtained by narrowing the planned division line while suppressing cracking during wafer thinning.

[0008] This invention provides a method for manufacturing chips that can narrow the planned division lines while suppressing cracking during wafer thinning. [Means for solving the problem]

[0009] The present invention A chip manufacturing method in which a workpiece having a functional layer formed on its surface is divided along the division lines, wherein multiple division lines are set on the surface side of a substrate, and a chip is manufactured by dividing the workpiece along the division lines. A machining groove forming step involves irradiating a laser beam along the planned division line to remove the functional layer and forming a machining groove shallower than the finished thickness in the substrate, A thinning step in which the back side of the substrate is processed to thin the substrate to the finished thickness, The process includes, after the thinning step, a splitting step in which an external force is applied to the workpiece to divide it into a plurality of chips along the machining groove. [Effects of the Invention]

[0010] According to the present invention, cracking during wafer thinning can be suppressed while narrowing the planned division line. [Brief explanation of the drawing]

[0011] [Figure 1] This flowchart shows an example of the manufacturing process for chip 11. [Figure 2] This figure shows an example of workpiece 1, where (A) is a perspective view of workpiece 1 and (B) is a cross-sectional view of workpiece 1. [Figure 3] This is a diagram illustrating the laser processing groove formation step S1. [Figure 4] It is a diagram for explaining the processing groove 16 formed by the laser processing groove forming step S1. [Figure 5] It is a diagram for explaining the surface protection sheet attaching step S2. [Figure 6] It is a diagram showing the workpiece 1 to which the surface protection sheet 3 is attached by the surface protection sheet attaching step S2. [Figure 7] It is a diagram for explaining the thinning step S3. [Figure 8] It is a diagram showing the workpiece 1 being thinned by the thinning step S3. [Figure 9] It is a diagram for explaining the film fixing step S4. [Figure 10] It is a diagram showing the workpiece 1 to which the die attach film 6 is fixed by the film fixing step S4. [Figure 11] It is a diagram for explaining the surface protection sheet peeling step S5. [Figure 12] It is a diagram for explaining the dividing step S6. [Figure 13] It is a diagram showing the state in which an external force is applied to the workpiece 1 by the dividing step S6. [Figure 14] It is a diagram showing the state in which the workpiece 1 is divided by the dividing step S6.

Mode for Carrying Out the Invention

[0012] Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 14.

[0013] (Method for manufacturing a chip) FIG. 1 is a flowchart showing an example of the processing of the method for manufacturing the chip 11. The manufacturing method of the chip 11 (see FIG. 14) according to an embodiment of the present invention is a method of manufacturing the chip 11 by dividing the workpiece 1 (see FIG. 2). As shown in FIG. 1, it includes a laser processing groove forming step S1, a surface protection sheet attaching step S2, a thinning step S3, a film fixing step S4, a surface protection sheet peeling step S5, and a dividing step S6. Note that the surface protection sheet attaching step S2 and the surface protection sheet peeling step S5 may be omitted.

[0014] (Workpiece) FIG. 2 is a perspective view and a cross-sectional view showing an example of the workpiece 1. The workpiece 1 is, for example, a substantially disk-shaped wafer or an optical device wafer made of a material such as Si (silicon), SiC (silicon carbide), GaN (gallium nitride), GaAs (gallium arsenide), or other semiconductors. Further, the workpiece 1 may be various plate-shaped processing materials such as ceramics, glass, a plate-shaped inorganic material substrate of sapphire system, a plate-shaped ductile material such as metal or resin. Further, the workpiece 1 may be a package substrate or the like including a plurality of device chips sealed with a mold resin or the like. FIG. 2 shows a wafer as an example of the workpiece 1.

[0015] The workpiece 1 shown in Figures 2(A) and (B) comprises a substrate 12 made of Si (silicon) or the like, a functional layer 13 such as an oxide film, nitride film, low-k film, wiring, and pattern formed on the surface 12a of the substrate 12, and a device circuit 14 formed on the surface of the functional layer 13. On the surface 1a of the workpiece 1, multiple intersecting streets are designated as division lines 15, and multiple regions partitioned by these division lines 15 are formed in a grid pattern. Device circuits 14 such as ICs (Integrated Circuits), LSIs (Large Scale Integrated Circuits), and MEMS (Micro Electro Mechanical Systems) are formed in each region partitioned by these division lines 15. When the workpiece 10 is divided along the division lines 15, individual chips 11 are formed. In this embodiment, the chips 11 are, for example, square in shape, but they may also be rectangular in shape.

[0016] Next, the steps S1 to S6 that constitute the manufacturing method of the chip 11 of one embodiment of the present invention will be described with reference to Figures 3 to 14.

[0017] (Laser-processed groove formation step S1) Figure 3 is a diagram illustrating the laser processing groove formation step S1, and Figure 4 is a diagram illustrating the processed groove 16 formed by the laser processing groove formation step S1. As shown in Figures 3 and 4, the laser processing groove formation step S1 is a process in which a laser beam 21 is irradiated along the division line 15 to remove the functional layer 13 and to form a processing groove 16 in the substrate 12 with a depth B shallower than the finished thickness A. For example, as shown in Figure 3, the laser irradiation unit 2 is set on the surface 1a side of the workpiece 1 at a predetermined interval, and the focusing point of the laser beam 21 emitted from the laser irradiation unit 2 is set. Then, while emitting the laser beam 21 from the laser irradiation unit 2 toward the division line 15, the laser irradiation unit 2 or the workpiece 1 is moved relative to the division line 15 to form the processing groove 16.

[0018] As shown in Figure 4, in the laser groove formation step S1, the groove 16 is formed such that the groove width formed on the back surface 12b of the substrate 12 is smaller than the groove width formed on the front surface 12a of the substrate 12. For example, in the laser groove formation step S1 of this embodiment, the laser is irradiated multiple times onto the same planned division line 15, and the focal point of the laser beam 21 is gradually deepened from the front surface 12a of the substrate 12 to form an inverted triangular or inverted trapezoidal groove 16. With a groove 16 of this shape, the division of the chip 11 in the division step S6 becomes easier. The reason for this will be explained later.

[0019] If the finished thickness of the substrate 12 is A and the depth of the processed groove 16 from the surface 12a of the substrate 12 is B, then in the laser processed groove formation step S1, B ≥ A × 0.1 It is desirable to form the machined groove 16 so as to satisfy the following conditions.

[0020] For example, if the finished thickness A of the workpiece 1 is 60 μm, the thickness of the functional layer 13 is 30 μm, and the finished thickness A of the substrate 12 is 30 μm, the depth B of the processing groove 16 formed in the substrate 12 must be at least 3 μm larger to make it difficult to divide the chip 11 in the dividing step S6. Also, if the finished thickness A of the workpiece 1 is 60 μm, the thickness of the functional layer 13 is 40 μm, and the finished thickness A of the substrate 12 is 20 μm, the depth B of the processing groove 16 formed in the substrate 12 must be at least 2 μm larger to make it difficult to divide the chip 11 in the dividing step S6. Furthermore, if the finished thickness A of the workpiece 1 is 60 μm, the thickness of the functional layer 13 is 10 μm, and the finished thickness A of the substrate 12 is 50 μm, the depth B of the processing groove 16 formed in the substrate 12 must be at least 5 μm larger to make it difficult to divide the chip 11 in the dividing step S6.

[0021] Furthermore, the deeper the processing groove 16, the easier it is to divide the chip 11 in the division step S6. However, if the processing groove 16 is deep, the laser processing groove formation step S1 takes more time. B <A×0.5 Satisfying these conditions is preferable in terms of productivity.

[0022] (Surface protection sheet application step S2) Figure 5 is a diagram illustrating the surface protection sheet application step S2, and Figure 6 is a diagram showing the workpiece 1 with the surface protection sheet 3 applied by the surface protection sheet application step S2. As shown in Figures 5 and 6, the surface protection sheet application step S2 is a process of applying a surface protection sheet 3 that covers the functional layer 13 to the surface 1a of the workpiece 1. The surface protection sheet 3 is not limited in terms of sheet material or adhesive, as long as it can protect the surface 1a of the workpiece 1 in the thinning step S3.

[0023] (Thinning step S3) Figure 7 is a diagram illustrating the thinning step S3, and Figure 8 is a diagram showing the workpiece 1 being thinned by the thinning step S3. As shown in Figures 7 and 8, the thinning step S3 is a process in which the back surface 12b of the substrate 12 is processed after the laser processing groove formation step S1 and the surface protection sheet attachment step S2 to thin the substrate 12 to a finished thickness A. For example, in this embodiment, the thinning step S3 is performed by a grinding apparatus 5 equipped with a holding table 51 and a grinding wheel 52. That is, the workpiece 1 is held on the holding table 51 with its back surface 1b facing upwards, and the holding table 51 is rotated at a first set speed. At the same time, the grinding wheel 52 is rotated at a second set speed, and the grinding wheel 521 provided on the lower surface of the grinding wheel 52 is brought into contact with the back surface 1b of the workpiece 1. As a result, the back surface 1b of the workpiece 1 is ground based on the difference in rotational speed between the holding table 51 and the grinding wheel 52, and the substrate 12 is thinned to a finished thickness A. Note that the thinning step S3 is not limited to grinding, but may also be performed by polishing, wet etching, dry etching, wafer cutting, etc.

[0024] (Film setting step S4) Figure 9 is a diagram illustrating the film fixing step S4, and Figure 10 is a diagram showing the workpiece 1 to which the die attach film 6 has been fixed by the film fixing step S4. As shown in Figures 9 and 10, the film fixing step S4 is a process of fixing the die attach film 6 to the back surface 12b of the substrate 12. The die attach film 6 is an adhesive film for die bonding and functions as an adhesive when the workpiece 1 is divided into chips 11 and then mounted on a lead frame or mounting board.

[0025] In the film fixing step S4 of this embodiment, the die attach film 6 is pre-integrated with the dicing sheet 7, and the die attach film 6 is fixed to the back surface 12b of the substrate 12 while the die attach film 6 and the dicing sheet 7 are supported by the ring frame 8. The ring frame 8 is an annular plate member formed of, for example, metal or resin, and has an opening larger than the outer diameter of the workpiece 1. The dicing sheet 7 is an expandable sheet member with an outer diameter larger than the opening of the ring frame 8, and is attached to the back surface of the ring frame 8 so as to cover the opening of the ring frame 8. As a result, the workpiece 1 is supported by the ring frame 8 via the die attach film 6 and the dicing sheet 7.

[0026] (Surface protective sheet peeling step S5) Figure 11 is a diagram illustrating the surface protective sheet peeling step S5. As shown in Figure 11, the surface protection sheet peeling step S5 is a process of peeling the surface protection sheet 3 from the surface 1a of the workpiece 1 supported by the ring frame 8.

[0027] (Splitting step S6) Figure 12 is a diagram illustrating the splitting step S6, Figure 13 shows the state in which an external force is applied to the workpiece 1 by the splitting step S6, and Figure 14 shows the state in which the workpiece 1 has been split by the splitting step S6. As shown in Figures 12 to 14, the splitting step S6 is a process of applying an external force to the workpiece 1 to split the workpiece 1 into multiple chips 11 along the machining groove 16. For example, an external force is applied to the workpiece 1 based on an expanding process that stretches the dicing sheet 7, and the workpiece 1 is split into multiple chips 11 by cracks 17 that extend from the machining groove 16 due to the external force. At this time, since the machining groove 16 is formed in the shape of an inverted triangle or an inverted trapezoid as described above, the external force promotes the extension of the cracks 17, making it easier to split the workpiece 1.

[0028] Furthermore, in the division step S6 of this embodiment, an external force is applied to the workpiece 1 including the die attach film 6 to divide it into multiple film-attached chips 11. For example, the expansion process is performed in a frozen state of -10 degrees Celsius. In other words, by utilizing the difference in physical properties—that the dicing sheet 7 maintains its expandability even in a frozen state of -10 degrees Celsius, while the die attach film 6 becomes easily torn in a frozen state of -10 degrees Celsius—the die attach film 6 is also divided integrally with the chips 11 during the expansion process.

[0029] As shown in Figures 12 and 13, the splitting step S6 of this embodiment is carried out using an expander 9. The expander 9 comprises a cylindrical base portion 91 on which a mounting surface for placing the ring frame 8 is formed, a clamp portion 92 for fixing the ring frame 8 to the mounting surface of the base portion 91, and a cylindrical expander portion 93 disposed within the base portion 91 for pushing and spreading the dicing sheet 7 attached to the ring frame 8 from below. Note that the splitting step S6 is not limited to an expanding process that stretches the dicing sheet 7, but may also be a breaking process in which the substrate 12 is pressed and split with something like a guillotine blade.

[0030] According to this method of manufacturing the chip 11, a laser beam is irradiated to form a processing groove 16 on the substrate 12 that is shallower than the finished thickness. This makes it possible to form a processing groove 16 that is narrower than the width of the cutting blade, and also reduces chipping compared to cutting blade processing. Therefore, it is possible to suppress cracking when the substrate 12 is thinned, and to narrow the planned division line 15 to increase the number of chips 11 obtained.

[0031] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to these examples. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention. Furthermore, the components of the above embodiments may be combined in any way without departing from the spirit of the invention.

[0032] For example, in the above embodiment, the processed groove 16 was formed in the laser processed groove formation step S1, then ground in the thinning step S3, and then divided into chips 11 in the dividing step S6. However, the invention is not limited to this, and the processed groove 16 may be formed in the laser processed groove formation step S1 after the thinning step S3, and then divided into chips 11 in the dividing step S6.

[0033] This specification contains at least the following information. Note that the components etc. in parentheses indicate those corresponding to the embodiments described above, but are not limited thereto.

[0034] (1) A chip manufacturing method in which a workpiece (workpiece 1) having a functional layer (functional layer 13) formed on the surface (surface 12a) side of a substrate (substrate 12) is divided along the division lines (chip 11), wherein a plurality of division lines (division lines 15) are set on the surface (surface 12a) side of the substrate (substrate 12), A processing groove forming step (laser processing groove forming step S1) involves irradiating a laser beam (laser beam 21) along the planned division line to remove the functional layer and forming a processing groove (processing groove 16) on the substrate that is shallower than the finished thickness, A thinning step (thinning step S3) is performed to process the back side (back side 12b) of the substrate to thin the substrate to the finished thickness, The process includes, after the thinning step, a splitting step (splitting step S6) in which an external force is applied to the workpiece to divide the workpiece into a plurality of chips along the machining groove. A method for manufacturing chips.

[0035] According to (1), by irradiating the substrate with a laser beam and forming a processing groove shallower than the finished thickness, it is possible to form a processing groove narrower than the width of the cutting blade, and chipping can be reduced compared to cutting blade processing. Therefore, cracking during wafer thinning can be suppressed, and the number of device chips obtained can be increased by narrowing the planned division line.

[0036] (2) A method for manufacturing a chip as described in (1), In the groove forming step, the groove is formed such that the groove width formed on the back side of the substrate is smaller than the groove width formed on the front side of the substrate. A method for manufacturing chips.

[0037] According to (2), when the chip is divided into multiple chips during the splitting step, cracks are more likely to propagate.

[0038] (3) A method for manufacturing a chip as described in (1) or (2), If the finished thickness of the substrate is A, and the depth of the processed groove from the surface of the substrate is B, In the aforementioned groove forming step, The machined groove is formed such that B ≥ A × 0.1. A method for manufacturing chips.

[0039] According to (3), when the chip is divided into multiple chips during the splitting step, cracks are more likely to spread.

[0040] (4) A method for manufacturing a chip as described in any of (1) to (3), The thinning step is performed after the groove forming step. A method for manufacturing chips.

[0041] According to (4), the situation in which the thinning step is performed before the processing groove formation step can be reduced compared to when the thinning step is performed before the processing groove formation step.

[0042] (5) A method for manufacturing a chip as described in any of (1) to (4), After the thinning step, the system further includes a fixing step (film fixing step S4) in which a die attach film (die attach film 6) is fixed to the back side of the substrate. In the division step, the external force is applied to the workpiece including the die attach film to divide it into a plurality of film-attached chips. A method for manufacturing chips.

[0043] According to (5), the die attach film for fixing the chip to the motherboard can be attached to the chip during the chip manufacturing stage, improving productivity.

[0044] (6) A method for manufacturing a chip as described in (4), After the groove forming step and before the thinning step, a surface protection sheet application step (surface protection sheet application step S2) is performed, in which a surface protection sheet (surface protection sheet 3) is applied to cover the functional layer formed on the surface of the substrate. The process includes a surface protection sheet peeling step (surface protection sheet peeling step S5) which is performed after the thinning step and before the dividing step, A method for manufacturing chips.

[0045] According to (6), the functional layer formed on the surface of the substrate during the thinning step can be protected. [Explanation of symbols]

[0046] 1 Workpiece 11 chips 12 circuit boards 12a Surface of the substrate 12b Back side of the circuit board 13 Functional Layers 15 planned division lines 16 Machining groove 21 Laser beam 3. Surface protection sheet 6. Die Touch Film S1 Laser processing groove formation step (processing groove formation step) S2 Surface protection sheet application step S3 Thinning step S4 Film setting step S5 Surface protective sheet peeling step S6 Split Step

Claims

1. A chip manufacturing method in which a workpiece having a functional layer formed on its surface is divided along the division lines, wherein multiple division lines are set on the surface side of a substrate, and a chip is manufactured by dividing the workpiece along the division lines. A machining groove forming step involves irradiating a laser beam along the planned division line to remove the functional layer and forming a machining groove shallower than the finished thickness in the substrate, A thinning step in which the back side of the substrate is processed to thin the substrate to the finished thickness, The process includes, after the thinning step, a splitting step in which an external force is applied to the workpiece to divide the workpiece into a plurality of chips along the machining groove. A method for manufacturing chips.

2. A method for manufacturing a chip according to claim 1, In the groove forming step, the groove is formed such that the groove width formed on the back side of the substrate is smaller than the groove width formed on the front side of the substrate. A method for manufacturing chips.

3. A method for manufacturing a chip according to claim 1 or 2, If the finished thickness of the substrate is A, and the depth of the processed groove from the surface of the substrate is B, In the aforementioned groove forming step, The machined groove is formed such that B ≥ A × 0.

1. A method for manufacturing chips.

4. A method for manufacturing a chip according to claim 1 or 2, The thinning step is performed after the groove forming step. A method for manufacturing chips.

5. A method for manufacturing a chip according to claim 3, The thinning step is performed after the groove forming step. A method for manufacturing chips.

6. A method for manufacturing a chip according to claim 1 or 2, The thinning step is followed by a fixing step of fixing the die attach film to the back side of the substrate, In the division step, the external force is applied to the workpiece including the die attach film to divide it into a plurality of film-attached chips. A method for manufacturing chips.

7. A method for manufacturing a chip according to claim 3, The thinning step is followed by a fixing step of fixing the die attach film to the back side of the substrate, In the division step, the external force is applied to the workpiece including the die attach film to divide it into a plurality of film-attached chips. A method for manufacturing chips.

8. A method for manufacturing a chip according to claim 4, The thinning step is followed by a fixing step of fixing the die attach film to the back side of the substrate, In the division step, the external force is applied to the workpiece including the die attach film to divide it into a plurality of film-attached chips. A method for manufacturing chips.

9. A method for manufacturing a chip according to claim 4, After the groove forming step and before the thinning step, a surface protection sheet application step is performed, in which a surface protection sheet is applied to cover the functional layer formed on the surface of the substrate. The system includes a surface protection sheet peeling step, which is performed after the thinning step and before the dividing step, in which the surface protection sheet is peeled off. A method for manufacturing chips.

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