Method for manufacturing a device chip

Abstract

To provide a manufacturing method of a device chip capable of suppressing thermal influence on a resin layer caused during division processing by a laser beam.SOLUTION: A device chip manufacturing method for manufacturing device chips by dividing a wafer in which a plurality of devices are formed in areas partitioned by division scheduled lines set in a grid pattern on the surface into individual devices includes a resin layer forming step 1 for forming a resin layer on the surface side of the wafer, a resin layer processing step 3 of irradiating with a laser beam with a first output along the division scheduled line from the side on which the resin layer is formed to form laser-processed grooves in the resin layer after the resin layer forming step 1, and a wafer cutting step 4 of irradiating with a laser beam along the laser processing groove with a second output higher than the first output to cut the wafer after the resin layer processing step 3.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a device chip.

Background Art

[0002] As a method for mounting a semiconductor chip having connection terminals (bumps) made of solder or the like, a method of bonding semiconductor chips via a sealing paste-like or film-like resin layer provided in advance on the semiconductor chip is known (see Patent Document 1). In the manufacturing process of the above semiconductor chip, in order to cope with the thinning and multi-stage lamination of the device chip, a resin layer is formed on the surface of a wafer whose back surface is ground and thinned, and dicing is performed from the resin layer side, so that a semiconductor chip with a resin layer formed thereon can be easily obtained, which has attracted attention.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when cutting a thinned wafer with a cutting blade, there is a problem that backside chipping frequently occurs. Therefore, a method of dicing by ablation using laser beam irradiation was considered. However, since the resin layer is vulnerable to heat, the resin is cured under the thermal influence of the laser beam, and the resin does not expand during thermocompression bonding performed at the mounting stage, resulting in a new problem of causing chip defects.

[0005] The present invention has been made in view of such problems, and an object thereof is to provide a method for manufacturing a device chip capable of suppressing the thermal influence on the resin layer generated during the division process by a laser beam.

Means for Solving the Problems

[0006] In order to solve the above-described problems and achieve the object, a method for manufacturing a device chip according to the present invention is a method for manufacturing a device chip in which a wafer having a plurality of devices formed in regions partitioned by division planned lines set in a grid pattern on the surface is divided into individual devices to manufacture the device chip, the method including: a resin layer forming step of forming a resin layer on the surface side of the wafer; after the resin layer forming step, a resin layer processing step of irradiating a laser beam along the division planned line from the side on which the resin layer is formed with a first output to form a laser processing groove in the resin layer; and after the resin layer processing step, a wafer cutting step of irradiating the laser beam along the laser processing groove with a second output larger than the first output to cut the wafer. Look, In the wafer cutting step, it is adjusted so that the laser beam is not irradiated on the side wall of the laser processing groove It is characterized by the above.

[0008] Further, the method for manufacturing a device chip according to the present invention may further include a protective film forming step of forming a protective film on the side on which the resin layer is formed after the resin layer forming step and before the resin layer processing step, and a protective film removing step of removing the protective film after the wafer cutting step.

[0009] In the method for manufacturing a device chip according to the present invention, the resin layer may be an insulating film.

Effect of the Invention

[0010] The present invention can suppress the thermal influence on the resin layer generated during the division process by the laser beam.

Brief Description of the Drawings

[0011]

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Embodiments for Carrying Out the Invention

[0012] Embodiments (embodiment modes) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the content described in the following embodiments. Further, the constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Also, various omissions, substitutions, or changes in the configuration can be made without departing from the gist of the present invention.

[0013] 〔Embodiment〕 A method for manufacturing a device chip 18 according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a wafer 10 to be processed in the method for manufacturing the device chip 18 of the embodiment. The wafer 10 is a disk-shaped semiconductor wafer, an optical device wafer, etc. having a substrate 11 made of silicon (Si), sapphire (Al2O3), gallium arsenide (GaAs), silicon carbide (SiC), or the like. The substrate 11 is a silicon substrate having a thickness of 30 μm or more and 50 μm or less in the embodiment.

[0014] The wafer 10 has a plurality of division planned lines 13 set in a grid pattern on the surface 12 of the substrate 11 and a plurality of devices 14 formed in regions partitioned by the division planned lines 13. The device 14 is, for example, an integrated circuit such as an IC (Integrated Circuit) or an LSI (Large Scale Integration), an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). The back surface 15 of the wafer 10 is the surface located on the side opposite to the surface 12 where the device 14 is formed.

[0015] In the embodiment, the wafer 10 is a TSV (Through-Silicon Via) wafer including a through electrode 16 (see FIG. 4 etc.) that penetrates the substrate 11 in a region corresponding to the device 14 and an electrode bump 17 connected to the through electrode 16 on the surface 12 side of the substrate 11. The electrode bump 17 has a height of about 200 μm and protrudes from the surface of the device 14. Note that the wafer 10 may be an interposer wafer including a through electrode 16 that penetrates the substrate 11 in a region corresponding to the device 14 and a redistribution layer (wiring layer) connected to the through electrode 16 on the surface 12 side of the substrate 11.

[0016] The wafer 10 is divided along the division planned lines 13 for each individual device 14 and separated into device chips 18. Note that the device chip 18 is square-shaped in FIG. 1, but may be rectangular-shaped.

[0017] Next, a method for manufacturing the device chip 18 according to the embodiment will be described. FIG. 2 is a flowchart showing the flow of the method for manufacturing the device chip 18 of the embodiment. The method for manufacturing the device chip 18 of the embodiment includes a resin layer forming step 1, a protective film forming step 2, a resin layer processing step 3, a wafer dicing step 4, and a protective film removing step 5.

[0018] (Resin layer forming step 1) FIG. 3 is a perspective view showing an example of the resin layer forming step 1 shown in FIG. 2. The resin layer forming step 1 is a step of forming a resin layer 22 on the surface 12 side of the wafer 10. In the embodiment, before forming the resin layer 22 on the surface 12 side of the wafer 10, the wafer 10 is fixed to an annular frame 20 and a tape 21.

[0019] The frame 20 has an opening larger than the outer diameter of the wafer 10 and is made of a material such as metal or resin. The tape 21 is an adhesive tape for fixing the wafer 10 to the frame 20. The tape 21 includes, for example, a base material layer made of a synthetic resin and a paste layer made of a synthetic resin laminated on the base material layer and having adhesiveness. When fixing the wafer 10 to the annular frame 20 and the tape 21, first, the tape 21 is attached to the back side of the frame 20, and then the wafer 10 is positioned at a predetermined position in the opening of the frame 20, and the back side 15 is attached to the tape 21.

[0020] In an embodiment, the resin layer 22 is an insulating film made of an adhesive resin, for example, an NCF (Non Conductive Film). The outer diameter of the resin layer 22 that is a film is substantially equal to the outer diameter of the wafer 10. Also, the thickness of the resin layer 22 is 15 μm in the embodiment. In the resin layer forming step 1, as shown in FIG. 3, the resin layer 22 is adhered from the surface 12 side of the wafer 10 fixed to the frame 20 and the tape 21 so as to cover the entire surface 12 of the wafer 10. The resin layer 22 is adhered in a state of covering the entire surface 12 of the wafer 10 so as to absorb the unevenness between the division planned line 13 and the device 14.

[0021] (Protective film forming step 2) FIG. 4 is a side view showing a partial cross section of an example of the protective film forming step 2 shown in FIG. 2. FIG. 5 is a cross-sectional view showing a main part of the wafer 10 in a state after FIG. 4 of the protective film forming step 2 shown in FIG. 2. The protective film forming step 2 is a step of forming a protective film 23 on the side of the wafer 10 where the resin layer 22 is formed. The protective film forming step 2 is carried out after the resin layer forming step 1 and before the resin layer processing step 3.

[0022] As shown in FIG. 4, in the protective film forming step 2 of the embodiment, the protective film 23 is formed using the protective film forming apparatus 30. The protective film forming apparatus 30 includes a spin coater in the embodiment. The protective film forming apparatus 30 includes a chuck table 31 having a holding surface 32, a clamp member 33, a rotating shaft member 34, and a resin supply nozzle 35. Note that the protective film forming apparatus 30 may be a protective film forming unit mounted on a laser processing apparatus 40 described later.

[0023] In the protective film forming step 2, first, the back surface 15 side of the wafer 10 is sucked and held on the holding surface 32 of the chuck table 31 via the tape 21, and the outer peripheral portion of the frame 20 is fixed by the clamp member 33. Next, with the chuck table 31 rotated around the axis by the rotary shaft member 34, the liquid resin 36 is dropped from the resin supply nozzle 35 onto the resin layer 22 formed on the surface 12 of the wafer 10. At this time, the resin supply nozzle 35 may be reciprocated in the radial direction of the wafer 10. The dropped liquid resin 36 flows from the center side to the outer peripheral side on the resin layer 22 formed on the surface 12 of the wafer 10 due to the centrifugal force generated by the rotation of the chuck table 31, and is applied to the entire surface of the resin layer 22.

[0024] The resin 36 is, for example, a water-soluble resin such as polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP). In the present invention, for example, Hogomax (registered trademark) manufactured by DISCO Corporation can be used as the resin 36. In the protective film forming step 2, the liquid resin 36 applied to the entire surface of the resin layer 22 on the surface 12 side of the wafer 10 is dried, and as shown in FIG. 5, a protective film 23 composed of the water-soluble resin 36 is formed on the upper layer of the resin layer 22 formed on the surface 12 side of the wafer 10. The thickness of the protective film 23 is about 5 μm or more and 15 μm or less in the embodiment.

[0025] (Resin layer processing step 3) FIG. 6 is a side view showing an example of the resin layer processing step 3 shown in FIG. 2 in partial cross section. FIG. 7 is a cross-sectional view showing a main part of the wafer 10 in a state after FIG. 6 of the resin layer processing step 3 shown in FIG. 2. The resin layer processing step 3 is a step of irradiating the resin layer 22 with a laser beam 45 at a first output along the dicing planned line 13 from the side where the resin layer 22 is formed to form a laser processing groove 24 in the resin layer 22. The resin layer processing step 3 is carried out after the resin layer forming step 1. The resin layer processing step 3 of the embodiment is further carried out after the protective film forming step 2.

[0026] As shown in FIG. 6, in the resin layer processing step 3 of the embodiment, a laser processing groove 24 is formed using a laser processing apparatus 40. The laser processing apparatus 40 includes a chuck table 41 having a holding surface 42, a clamp member 43, a laser beam irradiation unit 44, and a moving unit (not shown) that relatively moves the chuck table 41 and the condensing point of the laser beam emitted from the laser beam irradiation unit 44.

[0027] In the resin layer processing step 3, first, the back surface 15 side of the wafer 10 is sucked and held on the holding surface 42 of the chuck table 41 via the tape 21, and the outer peripheral portion of the frame 20 is fixed by the clamp member 43. Next, while relatively moving the chuck table 41 and the condensing point of the laser beam emitted from the laser beam irradiation unit 44 along the division planned line 13, the laser beam 45 is irradiated onto the side of the wafer 10 where the resin layer 22 is formed.

[0028] The laser beam 45 irradiated in the resin layer processing step 3 is a laser beam having a wavelength that is absorbable by the resin layer 22 and the protective film 23, and is irradiated with a first output. The laser beam 45 with the first output has an output of 5W, a number of passes of 5 passes, a repetition frequency of 300 kHz, and a feed rate of 1000 mm / s in the embodiment. The condensing point position of the laser beam 45 may be fixed or changed on the surface of the resin layer 22 as in the embodiment. Further, the laser beam 45 may be branched and irradiated in the processing feed direction.

[0029] As shown in FIG. 7, in the resin layer processing step 3, a laser beam 45 with a condensing point positioned on the surface of the resin layer 22 is irradiated along the planned division line 13, thereby forming a laser processing groove 24 along the planned division line 13. That is, by the laser beam 45, among the resin layer 22 and the protective film 23 covering the surface 12 of the wafer 10, the resin layer 22 and the protective film 23 in the region corresponding to the planned division line 13 are removed to form the laser processing groove 24. The laser processing groove 24 exposes the substrate 11 by removing a part of the resin layer 22 and the protective film 23 in the region corresponding to the planned division line 13.

[0030] At this time, on the side walls of the laser processing groove 24, a heat-affected zone 25 (Heat-Affected Zone: HAZ) where the resin is cured due to the irradiation of the laser beam 45 is formed. The laser beam 45 with the first output for removing the resin in the resin layer processing step 3 has a smaller output than the laser beam 46 with the second output for cutting the substrate 11 of the wafer 10 in the wafer cutting step 4 described later. Therefore, the heat influence on the resins of the resin layer 22 and the protective film 23 that are vulnerable to heat can be suppressed.

[0031] Furthermore, in the embodiment, the resin layer 22 formed on the surface 12 side of the wafer 10 is further covered with the protective film 23. Since the surface side that is most affected by the heat of the laser beam 45 and where the heat-affected zone 25 becomes large is covered with the protective film 23, the width 26 of the heat-affected zone 25 in the resin layer 22 can be reduced.

[0032] (Wafer cutting step 4) FIG. 8 is a side view showing an example of the wafer cutting step 4 shown in FIG. 2 in partial cross-section. FIG. 9 is a cross-sectional view showing a main part of the wafer 10 in a state after FIG. 8 of the wafer cutting step 4 shown in FIG. 2. The wafer cutting step 4 is a step of irradiating the laser beam 46 along the laser processing groove 24 with a second output larger than the first output to cut the wafer 10. The wafer cutting step 4 is performed after the resin layer processing step 3.

[0033] As shown in FIG. 8, in the wafer cutting step 4 of the embodiment, the wafer 10 is cut using the laser processing apparatus 40 used in the resin layer processing step 3, but a laser processing apparatus different from the laser processing apparatus 40 used in the resin layer processing step 3 may be used.

[0034] In the wafer cutting step 4, while relatively moving the chuck table 41 and the condensing point of the laser beam emitted from the laser beam irradiation unit 44 along the laser processing grooves 24 formed in the resin layer 22 and the protective film 23 on the surface 12 side of the wafer 10, the laser beam 46 is irradiated onto the surface 12 side of the substrate 11 exposed from the resin layer 22 of the wafer 10.

[0035] The laser beam 46 irradiated in the wafer cutting step 4 is a laser beam having a wavelength that is absorbent to the substrate 11 and is irradiated with a second output greater than the first output. In the embodiment, the laser beam 46 with the second output has an output of 7W, a number of passes of 15 passes, a repetition frequency of 300 kHz, and a feed rate of 1000 mm / s.

[0036] The condensing point position of the laser beam 46 may be fixed at the height of the surface of the resin layer 22 as in the embodiment, or may be changed to the surface 12 of the substrate 11, for example. Also, the laser beam 46 may be branched and irradiated in the processing feed direction. In the wafer cutting step 4, the laser beam 46 is adjusted so as not to be irradiated onto the side wall of the laser processing groove 24. The laser beam 46 is adjusted so as not to be irradiated onto the side wall of the laser processing groove 24, for example, by shaping the beam shape. Also, the laser beam 46 may be adjusted so as not to be irradiated onto the side wall of the laser processing groove 24, for example, by adjusting the output, the position of the condensing point, etc.

[0037] As shown in FIG. 9, in the wafer dicing step 4, the wafer 10 is diced along the planned division line 13 and separated into device chips 18 by irradiating a laser beam 46 with the condensing point positioned at the height of the surface of the resin layer 22 along the laser processing groove 24. At this time, the regions of the resin layer 22 and the protective film 23 along the planned division line 13 are removed by the laser processing groove 24, and the substrate 11 is exposed. For this reason, the laser beam 46 is directly irradiated onto the surface 12 of the substrate 11 along the planned division line 13, and is not irradiated onto the resin layer 22 and the protective film 23 which are the side walls of the laser processing groove 24. Thereby, the expansion of the heat affected layer 25 can be suppressed.

[0038] (Protective Film Removal Step 5) FIG. 10 is a side view showing an example of the protective film removal step 5 shown in FIG. 2 in a partial cross section. FIG. 11 is a cross-sectional view showing a main part of the wafer 10 in a state after FIG. 10 of the protective film removal step 5 shown in FIG. 2. The protective film removal step 5 is a step of removing the protective film 23. The protective film removal step 5 is carried out after the wafer dicing step 4.

[0039] As shown in FIG. 10, in the protective film removal step 5 of the embodiment, the cleaning device 50 uses a cleaning liquid 56 to clean and remove the protective film 23 made of a water-soluble resin that covers the surface of the resin layer 22 formed on the surface 12 side of the wafer 10. The cleaning device 50 includes a chuck table 51 having a holding surface 52, a clamp member 53, a rotating shaft member 54, and a cleaning liquid supply nozzle 55.

[0040] Note that the cleaning device 50 may be a device that also serves as the protective film forming device 30. More specifically, the chuck table 51, the clamp member 53, and the rotating shaft member 54 of the cleaning device 50 may also serve as the chuck table 31, the clamp member 33, and the rotating shaft member 34 of the protective film forming device 30. Further, the cleaning device 50 may be a cleaning unit mounted on the laser processing device 40.

[0041] In the protective film removal step 5, first, the back surface 15 side of the wafer 10 is sucked and held on the holding surface 52 of the chuck table 51 via the tape 21, and the outer peripheral portion of the frame 20 is fixed by the clamp member 53. Next, with the chuck table 51 rotated around the axis by the rotary shaft member 54, the cleaning liquid 56 is supplied from the cleaning liquid supply nozzle 55 toward the resin layer 22 formed on the front surface 12 of the wafer 10. At this time, the cleaning liquid supply nozzle 55 may be reciprocated in the radial direction of the wafer 10.

[0042] The cleaning liquid 56 is, for example, pressurized water whose water pressure is adjusted to about 10 MPa or more and 12 MPa or less in a water channel upstream of the cleaning liquid supply nozzle 55. The cleaning liquid 56 is, for example, pure water. The cleaning liquid 56 may be bubble water mixed with air. Also, so-called two-fluid cleaning by combining water and air may be performed.

[0043] The supplied cleaning liquid 56 flows from the center side to the outer peripheral side on the resin layer 22 formed on the front surface 12 of the wafer 10 by the centrifugal force generated by the rotation of the chuck table 31, and cleans the protective film 23 covering the surface of the resin layer 22. By cleaning the protective film 23 covering the surface of the resin layer 22, as shown in FIG. 11, the surface of the resin layer 22 is exposed. Thereby, the device chip 18 in which the resin layer 22 is formed on the front surface 12 of the substrate 11 can be obtained.

[0044] As described above, in the method for manufacturing the device chip 18 of the embodiment, after processing the resin layer 22 at a low output (first output), the substrate 11 is processed at a high output (second output), so that the thermal influence on the resin layer 22 generated during laser processing can be suppressed while surely dividing the substrate 11.

[0045] Also, the laser processing grooves 24 formed by processing at a low output can limit the scattering directions of high-temperature debris and plasma during high-output processing when cutting the substrate 11, so it can also contribute to suppressing the thermal influence due to the adhesion of debris and the diffusion of plasma.

[0046] Furthermore, by forming the protective film 23 that covers the surface of the resin layer 22, the heat-affected layer 25 can be suppressed. When the protective film 23 is formed as in the embodiment, the resin layer 22 is processed with the first output, and the substrate 11 is processed with the second output, the width 26 of the heat-affected layer 25 is about 45 μm. On the other hand, for example, when the protective film 23 is formed and the resin layer 22 and the substrate 11 are processed with a laser beam of the same output, the width 26 of the heat-affected layer 25 is about 60 μm. Furthermore, for example, when the protective film 23 is not formed and the resin layer 22 and the substrate 11 are processed with a laser beam of the same output, the width 26 of the heat-affected layer 25 is about 80 μm.

[0047] Also, in the embodiment, it is preferable that the resin layer processing step 3 and the wafer cutting step 4 are continuously performed, and the protective film removing step 5 is performed immediately after the wafer cutting step 4. Note that immediately after performing the wafer cutting step 4 means after the wafer cutting step 4 and after the required time has elapsed until the wafer 10 on which the wafer cutting step 4 has been performed by the laser processing apparatus 40 is transported to the cleaning apparatus 50. By performing the protective film removing step 5 immediately after performing the resin layer processing step 3 and the wafer cutting step 4, the debris attached to the protective film 23 during the laser processing can be removed before it gradually deteriorates and becomes difficult to remove.

[0048] Note that the present invention is not limited to the above-described embodiment. That is, various modifications can be made without departing from the gist of the present invention. Also, for example, in the resin layer processing step 3 shown in FIGS. 6 and 7 of the embodiment, a part of the resin layer 22 and the protective film 23 in the region corresponding to the division planned line 13 was removed to expose the substrate 11, but in the present invention, it is not always necessary to expose the substrate 11. That is, if the resin layer 22 in the region along the division planned line 13 has been removed by a predetermined amount after the resin layer processing step 3, the effect of suppressing the expansion of the heat-affected layer 25 can be similarly obtained in the wafer cutting step 4.

Explanation of Reference Numerals

[0049] 10 Wafer 11 Substrate 12 Surface 13 Predetermined dividing line 14 Device 15 Back surface 18 Device chip 22 Resin layer 23 Protective film 24 Laser processing groove 25 Heat affected layer 26 Width 45, 46 Laser beam

Claims

1. A method for manufacturing a device chip that manufactures a device chip by dividing a wafer in which a plurality of devices are formed in regions partitioned by division planned lines set in a grid pattern on the surface into individual devices, a resin layer forming step of forming a resin layer on the surface side of the wafer; after the resin layer forming step, a resin layer processing step of irradiating a laser beam along the division planned line from the side on which the resin layer is formed with a first output to form a laser processing groove in the resin layer; after the resin layer processing step, a wafer cutting step of irradiating a laser beam along the laser processing groove with a second output larger than the first output to cut the wafer; including: in the wafer cutting step, it is characterized in that the laser beam is adjusted so as not to irradiate the side wall of the laser processing groove. A method for manufacturing a device chip.

2. a protective film forming step of forming a protective film on the side on which the resin layer is formed after the resin layer forming step and before the resin layer processing step; a protective film removing step of removing the protective film after the wafer cutting step; further characterized by including: The method for manufacturing a device chip according to claim 1.

3. The resin layer is an insulating film, characterized in that The method for manufacturing a device chip according to claim 1 or 2.

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