Method of manufacturing device chip

Abstract

(Problem) A method for manufacturing a device chip capable of suppressing thermal effects on a resin layer during segmentation processing by a laser beam is provided. (Solution) A method for manufacturing a device chip comprises dividing a wafer, in which a plurality of devices are formed in an area partitioned by a grid-shaped partitioning line set on the surface, into individual devices to manufacture the device chip, and comprises a resin layer forming step (1) for forming a resin layer on the surface side of the wafer, a resin layer processing step (3) for forming a laser processing groove in the resin layer by irradiating a laser beam with a first output along the partitioning line from the side where the resin layer is formed after the resin layer forming step (1), and a wafer cutting step (4) for cutting the wafer by irradiating a laser beam along the laser processing groove with a second output greater than the first output after the resin layer processing step (3).

Description

Technology Field

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

[0002] A method for mounting a semiconductor chip having connection terminals (bumps) made of solder or the like is known, in which semiconductor chips are joined together through a resin layer in the form of a paste or film for sealing that is pre-installed on the semiconductor chip (see Patent Document 1). In the above semiconductor chip manufacturing process, in order to accommodate thinning or multi-stage stacking of device chips, a resin layer is formed on the surface of a wafer that has been thinned by grinding the back side, and by dicing from the resin layer side, a semiconductor chip with a resin layer formed thereon can be easily obtained, which is attracting attention. Prior art literature

[0003] Patent Document 1: Japanese Published Patent Application No. 2016-92188 The problem to be solved

[0004] However, when cutting thin wafers with a cutting blade, there was a problem with significant backside chipping. Therefore, a method of dicing by ablation using laser beam irradiation was considered, but a new problem was revealed: since the resin layer is sensitive to heat, the resin hardens under the heat of the laser beam, preventing the resin from spreading during the thermal compression performed in the mounting stage, which causes chip defects.

[0005] The present invention has been made in consideration of these problems, and its purpose is to provide a method for manufacturing a device chip capable of suppressing thermal effects on a resin layer during segmentation processing by a laser beam. means of solving the problem

[0006] To solve the above problem and achieve the objective, the method for manufacturing a device chip according to the present invention is a method for manufacturing a device chip by dividing a wafer, in which a plurality of devices are formed in an area partitioned by a grid-shaped partitioning line set on the surface, into individual devices to manufacture the device chip, and is characterized by comprising: a resin layer forming step of forming a resin layer on the surface side of the wafer; a resin layer processing step of forming a laser processing groove in the resin layer by irradiating a laser beam with a first output along the partitioning line from the side where the resin layer is formed after the resin layer forming step; and a wafer cutting step of cutting the wafer by irradiating a laser beam along the laser processing groove with a second output greater than the first output after the resin layer processing step.

[0007] In addition, in the method for manufacturing a device chip of the present invention, during the wafer cutting step, the laser beam may be adjusted so as not to be irradiated onto the side wall of the laser processing groove.

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

[0009] In addition, in the method for manufacturing a device chip of the present invention, the resin layer may be an insulating film. Effects of the invention

[0010] The present invention can suppress the thermal effect on the resin layer that occurs during segmentation processing by a laser beam. Brief explanation of the drawing

[0011] FIG. 1 is a perspective view of a wafer to be processed in a method for manufacturing a device chip of an embodiment. Figure 2 is a flowchart diagram showing the flow of a method for manufacturing a device chip of an embodiment. FIG. 3 is a perspective view showing an example of the resin layer formation step shown in FIG. 2. FIG. 4 is a side view showing a partial cross-section of an example of the protective film formation step shown in FIG. 2. Figure 5 is a cross-sectional view showing the main part of a wafer in a state after Figure 4 of the protective film formation step shown in Figure 2. FIG. 6 is a side view showing a partial cross-section of an example of the resin layer processing step shown in FIG. 2. Figure 7 is a cross-sectional view showing the main part of a wafer in a state after Figure 6 of the resin layer processing step shown in Figure 2. FIG. 8 is a side view showing a partial cross-section of an example of the wafer cutting step shown in FIG. 2. FIG. 9 is a cross-sectional view showing the main part of a wafer in a state after FIG. 8 of the wafer cutting step shown in FIG. 2. FIG. 10 is a side view showing a partial cross-section of an example of the protective film removal step shown in FIG. 2. FIG. 11 is a cross-sectional view showing the main part of the wafer in a state after FIG. 10 of the protective film removal step shown in FIG. 2. Specific details for implementing the invention

[0012] A form for carrying out the present invention (an embodiment) will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. Furthermore, the components described below include those that can be easily conceived by those skilled in the art and are substantially identical. Additionally, the configurations described below can be appropriately combined. Furthermore, various omissions, substitutions, or changes to the configurations may be made within the scope of not departing from the gist of the present invention.

[0013] [Embodiment]

[0014] A method for manufacturing a device chip (18) according to an embodiment of the present invention will be described based on the drawings. FIG. 1 is a perspective view of a wafer (10) that is the subject of processing in the method for manufacturing a device chip (18) of an embodiment. The wafer (10) is a wafer such as a semiconductor wafer or an optical device wafer in the shape of a disc, having silicon (Si), sapphire (Al2O3), gallium arsenide (GaAs), or silicon carbide (SiC), etc., as the substrate (11). In the embodiment, the substrate (11) is a silicon substrate with a thickness of 30 μm or more and 50 μm or less.

[0015] A wafer (10) has a plurality of planned division lines (13) set in a grid shape on the surface (12) of a substrate (11), and a plurality of devices (14) formed in the area partitioned by the planned division lines (13). The devices (14) are, for example, integrated circuits such as IC (Integrated Circuit) or LSI (Large Scale Integration), image sensors such as CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor). The surface of the wafer (10) located opposite to the surface (12) on which the devices (14) are formed is made into a back surface (15).

[0016] In an embodiment, the wafer (10) is a TSV (Through-Silicon Via) wafer comprising a through electrode (16) that penetrates the substrate (11) in an area corresponding to the device (14) (see FIG. 4, etc.) 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). Additionally, the wafer (10) may be an interposer wafer comprising, for example, a through electrode (16) that penetrates the substrate (11) in an area 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).

[0017] The wafer (10) is divided into individual devices (14) along the planned division line (13) and individualized into device chips (18). Additionally, the device chips (18) are square in shape in FIG. 1, but may also be rectangular in shape.

[0018] Next, a method for manufacturing a device chip (18) according to an embodiment is described. FIG. 2 is a flowchart showing the flow of a method for manufacturing a device chip (18) according to an embodiment. The method for manufacturing a device chip (18) according to an embodiment includes a resin layer forming step (1), a protective film forming step (2), a resin layer processing step (3), a wafer cutting step (4), and a protective film removal step (5).

[0019] (Step of forming a resin layer (1))

[0020] FIG. 3 is a perspective view showing an example of the resin layer formation step (1) shown in FIG. 2. The resin layer formation step (1) is a step of forming a resin layer (22) on the surface (12) side of a wafer (10). In an 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).

[0021] 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 substrate layer made of synthetic resin and a paste layer made of synthetic resin that is laminated to the substrate layer and has adhesive properties. 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).

[0022] In the embodiment, the resin layer (22) is an insulating film composed of an adhesive resin, for example, a Non Conductive Film (NCF). The outer diameter of the resin layer (22) is approximately equal to the outer diameter of the wafer (10). In addition, the thickness of the resin layer (22) in the embodiment is 15 μm. In the resin layer formation step (1), as shown in FIG. 3, the resin layer (22) is attached from the side of the surface (12) of the wafer (10) fixed to the frame (20) and the tape (21) to cover the entire surface (12) of the wafer (10). The resin layer (22) is adhered while covering the entire surface (12) of the wafer (10) to absorb irregularities of the planned division line (13) and the device (14).

[0023] (Protective film formation step (2))

[0024] FIG. 4 is a side view showing a partial cross-sectional view of an example of the protective film formation step (2) shown in FIG. 2. FIG. 5 is a cross-sectional view showing a main part of a wafer (10) in a state after FIG. 4 of the protective film formation step (2) shown in FIG. 2. The protective film formation 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 formation step (2) is performed after the resin layer formation step (1) and before the resin layer processing step (3).

[0025] As shown in FIG. 4, in the protective film forming step (2) of the embodiment, a protective film (23) is formed using a protective film forming device (30). In the embodiment, the protective film forming device (30) includes a spin coater. The protective film forming device (30) includes a chuck table (31) having a retaining surface (32), a clamp member (33), a rotating shaft member (34), and a resin supply nozzle (35). Additionally, the protective film forming device (30) may be a protective film forming unit mounted on a laser processing device (40) described later.

[0026] In the protective film formation step (2), first, the back side (15) of the wafer (10) is held in place by suction on the holding surface (32) of the chuck table (31) through the tape (21), and the outer periphery of the frame (20) is fixed with the clamp member (33). Next, while the chuck table (31) is rotated around the axis by the rotation axis member (34), 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 moved back and forth in the radial direction of the wafer (10). The dropped liquid resin (36) flows from the center side toward the outer periphery side onto the resin layer (22) formed on the surface (12) of the wafer (10) by the centrifugal force generated by the rotation of the chuck table (31), and is applied to the front surface of the resin layer (22).

[0027] The resin (36) is a water-soluble resin, for example, polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP). In addition, in the present invention, Hogomax (registered trademark) manufactured by DISCO Co., Ltd. may be used as the resin (36). In the protective film formation 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 a layer higher than the resin layer (22) formed on the surface (12) side of the wafer (10). In the embodiment, the thickness of the protective film (23) is approximately 5 μm or more and 15 μm or less.

[0028] (Resin layer processing step (3))

[0029] FIG. 6 is a side view showing a partial cross-sectional view of an example of the resin layer processing step (3) shown in FIG. 2. FIG. 7 is a cross-sectional view showing the main part of a 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 a laser beam (45) with a first output along a planned division line (13) from the side where the resin layer (22) is formed, and forming a laser processing groove (24) in the resin layer (22). The resin layer processing step (3) is performed after the resin layer formation step (1). The resin layer processing step (3) of the embodiment is also performed after the protective film formation step (2).

[0030] As shown in FIG. 6, in the resin layer processing step (3) of the embodiment, a laser processing device (40) is used to form a laser processing groove (24). The laser processing device (40) includes a chuck table (41) having a retaining surface (42), a clamp member (43), a laser beam irradiation unit (44), and a moving unit (not shown) that moves the collecting point of the laser beam emitted from the chuck table (41) and the laser beam irradiation unit (44) relative to each other.

[0031] In the resin layer processing step (3), first, the back side (15) of the wafer (10) is held in place by suction on the holding surface (42) of the chuck table (41) through the tape (21), and the outer periphery of the frame (20) is fixed with a clamp member (43). Next, while moving the point of focus of the laser beam emitted from the chuck table (41) and the laser beam irradiation unit (44) relative to the planned split line (13), the laser beam (45) is irradiated onto the side of the wafer (10) where the resin layer (22) is formed.

[0032] The laser beam (45) irradiated during the resin layer processing step (3) is a laser beam of a wavelength that has absorption properties with respect to the resin layer (22) and the protective film (23), and is irradiated at a first output. In the embodiment, the laser beam (45) of the first output has an output of 5 W, a number of passes of 5 passes, a repetition frequency of 300 kHz, and a feed speed of 1000 mm / s. As in the embodiment, the position of the focusing point of the laser beam (45) may be fixed on the surface of the resin layer (22) or may be changed. Additionally, the laser beam (45) may be branched and irradiated in the processing feed direction.

[0033] As shown in FIG. 7, in the resin layer processing step (3), a laser beam (45) with a focused 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), the resin layer (22) and the protective film (23) covering the surface (12) of the wafer (10) are removed in the area corresponding to the planned division line (13), thereby forming a laser processing groove (24). The laser processing groove (24) removes a portion of the resin layer (22) and the protective film (23) in the area corresponding to the planned division line (13), thereby exposing the substrate (11).

[0034] At this time, a heat-affected zone (HAZ) (25) (Heat-Affected Zone: HAZ) is formed on the side wall of the laser processing groove (24) in which the resin is cured by heat influence from the irradiation of the laser beam (45). The first output laser beam (45) for removing the resin in the resin layer processing step (3) has a lower output than the second output laser beam (46) for cutting the substrate (11) of the wafer (10) in the wafer cutting step (4) described later. Because of this, the heat influence on the resin of the heat-sensitive resin layer (22) and the protective film (23) can be suppressed.

[0035] In addition, in the embodiment, the resin layer (22) formed on the surface (12) side of the wafer (10) is covered again with a protective film (23). Since the surface side, which is most affected by the heat of the laser beam (45) and has a larger heat-affected layer (25), is covered with the protective film (23), the width (26) of the heat-affected layer (25) in the resin layer (22) can be reduced.

[0036] (Wafer cutting step (4))

[0037] FIG. 8 is a side view showing a partial cross-sectional view of an example of the wafer cutting step (4) shown in FIG. 2. FIG. 9 is a cross-sectional view showing the 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 cutting the wafer (10) by irradiating a laser beam (46) along a laser processing groove (24) with a second output greater than the first output. The wafer cutting step (4) is performed after the resin layer processing step (3).

[0038] As shown in FIG. 8, in the wafer cutting step (4) of the embodiment, the wafer (10) is cut using the laser processing device (40) used in the resin layer processing step (3), but a different laser processing device may be used than the laser processing device (40) used in the resin layer processing step (3).

[0039] In the wafer cutting step (4), a laser beam (46) is irradiated onto the surface (12) side of the substrate (11) exposed from the resin layer (22) of the wafer (10) while relatively moving the point of focus of the laser beam emitted from the chuck table (41) and the laser beam irradiation unit (44) along the laser processing groove (24) formed in the resin layer (22) and the protective film (23) on the surface (12) side of the wafer (10).

[0040] The laser beam (46) irradiated in the wafer cutting step (4) is a laser beam of a wavelength that is absorbent to the substrate (11) and is irradiated with a second output greater than the first output. In an embodiment, the laser beam (46) of the second output has an output of 7 W, a number of passes of 15 passes, a repetition frequency of 300 kHz, and a feed speed of 1000 mm / s.

[0041] The laser beam (46) may have its focusing point position fixed at the height of the surface of the resin layer (22) as in the embodiment, or, for example, may be changed to the surface (12) of the substrate (11). Additionally, the laser beam (46) may be branched and irradiated in the processing transfer direction. In the wafer cutting step (4), the laser beam (46) is adjusted so that it is not irradiated onto the side wall of the laser processing groove (24). The laser beam (46) is adjusted so that it is not irradiated onto the side wall of the laser processing groove (24), for example, by forming the beam shape. Additionally, the laser beam (46) may be adjusted so that it is not irradiated onto the side wall of the laser processing groove (24), for example, by adjusting the output or the position of the focusing point.

[0042] As shown in FIG. 9, in the wafer cutting step (4), a laser beam (46) with a focused point positioned at the height of the surface of the resin layer (22) is irradiated along the laser processing groove (24), thereby dividing the wafer (10) along the planned division line (13) and individualizing it into device chips (18). At this time, the area along the planned division line (13) of the resin layer (22) and the protective film (23) is removed by the laser processing groove (24), and the substrate (11) is exposed. Because of this, the laser beam (46) is irradiated directly 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). By doing so, the expansion of the heat affected layer (25) can be suppressed.

[0043] (Protective film removal step (5))

[0044] FIG. 10 is a side view showing a partial cross-sectional view of an example of the protective film removal step (5) shown in FIG. 2. 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 performed after the wafer cutting step (4).

[0045] As shown in FIG. 10, in the protective film removal step (5) of the embodiment, a protective film (23) composed of a water-soluble resin covering the surface of a resin layer (22) formed on the surface (12) side of a wafer (10) is removed by cleaning with a cleaning liquid (56) by a cleaning device (50). The cleaning device (50) includes a chuck table (51) having a retaining surface (52), a clamp member (53), a rotating shaft member (54), and a cleaning liquid supply nozzle (55).

[0046] Additionally, the cleaning device (50) may be a device that is combined with the protective film forming device (30). More specifically, the chuck table (51), clamp member (53), and rotational axis member (54) of the cleaning device (50) may be combined with the chuck table (31), clamp member (33), and rotational axis member (34) of the protective film forming device (30). Additionally, the cleaning device (50) may be a cleaning unit mounted on the laser processing device (40).

[0047] In the protective film removal step (5), first, the back side (15) of the wafer (10) is held in place by suction on the holding surface (52) of the chuck table (51) through the tape (21), and the outer periphery of the frame (20) is fixed with the clamp member (53). Next, while the chuck table (51) is rotated around the axis by the rotation axis member (54), the cleaning liquid (56) is supplied from the cleaning liquid supply nozzle (55) toward the resin layer (22) formed on the surface (12) of the wafer (10). At this time, the cleaning liquid supply nozzle (55) may be moved back and forth in the radial direction of the wafer (10).

[0048] The cleaning solution (56) is, for example, pressurized water with a water pressure adjusted to 10 MPa or more and 12 MPa or less in a waterway upstream of the cleaning solution supply nozzle (55). The cleaning solution (56) is, for example, pure water. The cleaning solution (56) may also be bubble water mixed with air. In addition, cleaning may be performed using a so-called two-fluid mixture of water and air.

[0049] The supplied cleaning solution (56) flows from the center side toward the outer side of the resin layer (22) formed on the 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), the surface of the resin layer (22) is exposed as shown in FIG. 11. By doing so, a device chip (18) having a resin layer (22) formed on the surface (12) of the substrate (11) can be obtained.

[0050] As described above, in the method for manufacturing the device chip (18) of the embodiment, the substrate (11) can be reliably divided while suppressing the thermal effect on the resin layer (22) that occurs during laser processing by processing the resin layer (22) with low power (first power) and then processing the substrate (11) with high power (second power).

[0051] In addition, the laser processing groove (24) formed by processing at low power can limit the direction of scattering of high-temperature debris or plasma during high-power processing when cutting the substrate (11), thus contributing to the suppression of thermal effects caused by the attachment of debris or the diffusion of plasma.

[0052] Additionally, by forming a 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 a first output, and the substrate (11) is processed with a second output, the width (26) of the heat-affected layer (25) is approximately 45 μm. In contrast, 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 approximately 60 μm. Also, for example, when the resin layer (22) and the substrate (11) are processed with a laser beam of the same output without forming the protective film (23), the width (26) of the heat-affected layer (25) is approximately 80 μm.

[0053] In addition, in the embodiment, it is preferable that the resin layer processing step (3) and the wafer cutting step (4) are performed continuously, and that the protective film removal step (5) is performed immediately after the wafer cutting step (4). Furthermore, "immediately after the wafer cutting step (4)" refers to the time elapsed after the wafer cutting step (4) and after the wafer (10) on which the wafer cutting step (4) was performed by the laser processing device (40) is returned to the cleaning device (50). By performing the protective film removal step (5) immediately after the resin layer processing step (3) and the wafer cutting step (4), debris attached to the protective film (23) during laser processing can be removed before it gradually deteriorates and becomes difficult to remove.

[0054] Furthermore, the present invention is not limited to the above embodiments. That is, it can be implemented with various modifications within the scope of not deviating from the gist of the present invention. Also, for example, in the resin layer processing step (3) shown in FIGS. 6 and FIGS. 7 of the embodiment, a portion of the resin layer (22) and protective film (23) in the area corresponding to the planned division line (13) is removed to expose the substrate (11), but in the present invention, it is not necessary to expose the substrate (11). That is, if a predetermined amount of the resin layer (22) in the area along the planned division line (13) is removed after the resin layer processing step (3), the same effect of suppressing the expansion of the heat affected layer (25) in the wafer cutting step (4) can be obtained. Explanation of the symbols

[0055] 10 wafers 11 boards 12 surfaces 13 lines scheduled for division 14 devices If it's 15 18 device chips 22 resin layer 23 Shield 24 laser-processed grooves 25 heat-affected zone 26 width 45, 46 Laser Beam

Claims

Claim 1 A method for manufacturing a device chip, comprising dividing a wafer having a plurality of devices formed in an area partitioned by a grid-shaped planned-division line on the surface into individual devices to manufacture the device chip, the method comprising: a resin layer forming step of forming a resin layer on the surface side of the wafer; a resin layer processing step of forming a laser processing groove in the resin layer by irradiating a laser beam with a first output along the planned-division line from the side where the resin layer is formed after the resin layer forming step; and a wafer cutting step of cutting the wafer by irradiating a laser beam along the laser processing groove with a second output greater than the first output after the resin layer processing step, wherein in the wafer cutting step, the laser beam is adjusted so as not to be irradiated on the sidewall of the laser processing groove. Claim 2 A method for manufacturing a device chip according to claim 1, further comprising a protective film forming step for 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 removal step for removing the protective film after the wafer cutting step. Claim 3 A method for manufacturing a device chip, characterized in that, in claim 1 or 2, the resin layer is an insulating film. Claim 4 delete

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