Method for manufacturing semiconductor device

Abstract

This method for manufacturing a semiconductor device is provided with: a step for adhering a support plate to a first surface of a semiconductor substrate having a plurality of element regions; a step for forming, after the step for adhering the support plate, a metal film across the plurality of element regions on a second surface located on the back side of the first surface; a step for dividing the metal film along a boundary by pressing a pressing member against the surface of the metal film along the boundary of the element region, and forming a crack in the semiconductor substrate extending along the boundary and in the thickness direction of the semiconductor substrate; a step for peeling the support plate from the first surface after the step for forming the crack; and a step in which a dividing member is pressed against the semiconductor substrate along the boundary from the first surface side to divide the semiconductor substrate along the boundary. As a result, the semiconductor substrate on which the metal film is formed can be divided with good precision by dicing and cutting processes.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a method for manufacturing a semiconductor device. Background Art

[0002] Patent Document 1 discloses a technique for dividing semiconductor substrates using a scribing and breaking method. In Patent Document 1, a pressing member is first pressed against the semiconductor substrate surface along the boundary between adjacent component regions while the semiconductor substrate is fixed to a support plate, forming a crack within the semiconductor substrate along this boundary. Next, a metal film is formed on the semiconductor substrate surface spanning multiple component regions. After the support plate is removed, a dividing member is pressed against the semiconductor substrate's backside along this boundary, dividing the semiconductor substrate and metal film along this boundary.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2023-179261 Summary of the Invention

[0006] In Patent Document 1, the metal film is formed across multiple device regions. Therefore, when the support plate is removed, the film stress of the metal film causes the semiconductor substrate to warp. This makes it difficult to accurately press the dividing member against the semiconductor substrate, potentially creating gaps in the singulated semiconductor devices. This specification proposes a new technology for accurately dividing semiconductor substrates with metal films through scribing and cutting processes.

[0007] According to a technical solution of a method for manufacturing a semiconductor device disclosed in this specification, the method comprises the following steps: a step of pasting a support plate onto a first surface of a semiconductor substrate having a plurality of element regions; a step of forming a metal film spanning the plurality of element regions on a second surface located on the back side of the first surface after the step of pasting the support plate; a step of pushing a pressing component along the boundary of the element regions on the surface of the metal film, thereby dividing the metal film along the boundary and forming a crack in the semiconductor substrate extending along the boundary and in the thickness direction of the semiconductor substrate; a step of peeling the support plate from the first surface after the step of forming the crack; and a step of pushing a dividing component toward the semiconductor substrate along the boundary from the first surface side, thereby dividing the semiconductor substrate along the boundary.

[0008] In this manufacturing method, a metal film is formed on the second surface of the semiconductor substrate while a support plate is attached to the first surface of the semiconductor substrate. Subsequently, a pressing member is pressed against the surface of the metal film, thereby dividing the metal film along the boundaries between the component regions and forming cracks in the semiconductor substrate. Because the metal film is divided, the film stress applied to the semiconductor substrate is reduced when the support plate is peeled from the semiconductor substrate. Consequently, warping of the semiconductor substrate caused by the film stress of the metal film is reduced. Consequently, the dividing member can be pressed against the semiconductor substrate with high precision along the boundaries between the component regions, thereby preventing the formation of cracks in the manufactured semiconductor device. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a plan view of a semiconductor substrate.

[0010] Figure 2 It is a figure for demonstrating the support plate pasting process.

[0011] Figure 3 This is a diagram for explaining the grinding process.

[0012] Figure 4 It is a diagram for explaining the silicide formation process.

[0013] Figure 5 It is a diagram for explaining the silicide formation process.

[0014] Figure 6 It is a diagram for explaining the metal film forming process.

[0015] Figure 7 It is a diagram for explaining the crack forming process.

[0016] Figure 8 This is a diagram for explaining the cutting tape pasting process.

[0017] Figure 9 It is a figure for demonstrating the support plate peeling process.

[0018] Figure 10 It is a diagram for explaining the protective member covering step.

[0019] Figure 11 It is a diagram for explaining the segmentation process.

[0020] Figure 12 This is a diagram for explaining a die pick process. DETAILED DESCRIPTION

[0021] In one example of the manufacturing method disclosed in this specification, the step of grinding the second surface of the semiconductor substrate may be further included after the step of attaching the support plate and before the step of forming the metal film.

[0022] With such a structure, the manufactured semiconductor device can be miniaturized.

[0023] In the manufacturing method of one example disclosed in this specification, the metal film may include a silicide layer, and the silicide layer may be formed at an interface between the metal film and the second surface of the semiconductor substrate.

[0024] According to such a structure, the contact resistance between the metal film and the semiconductor substrate can be reduced.

[0025] (Example)

[0026] The manufacturing method of the embodiment will be described with reference to the drawings. Figure 1 FIG is a plan view of a semiconductor substrate 2 in which a plurality of element regions 3 are formed in a matrix. Figure 1 , each element region 3 is schematically represented by a solid line. For ease of explanation, the boundary between adjacent element regions 3 and the line that becomes the end edge of each element region (semiconductor device) obtained by dividing the semiconductor substrate 2 into each element region 3 are called the predetermined dividing line 4. The predetermined dividing line 4 is not a line actually recorded on the semiconductor substrate 2, but an imaginary line. The predetermined dividing line 4 can also be a line or groove actually drawn on the semiconductor substrate 2 so that it can be visually seen. Semiconductor elements having functions such as transistors and diodes are formed in each element region 3.

[0027] The semiconductor substrate 2 is made of SiC (silicon carbide). In addition, the semiconductor substrate 2 can also be made of other semiconductor materials such as Si (silicon) and GaN (gallium nitride). Figure 2 As shown in FIG. 1 , the semiconductor substrate 2 has a first surface 2a and a second surface 2b located on the back side of the first surface 2a. On the first surface 2a of the semiconductor substrate 2, a main structure 6 of the semiconductor element (a structure for realizing the function of the semiconductor device) such as a trench and a gate electrode is formed.

[0028] The manufacturing method of the embodiment includes a support plate attaching step, a grinding step, a metal film forming step, a crack forming step, a dicing tape attaching step, a support plate peeling step, a protective member covering step, and a dividing step.

[0029] (Support plate pasting process)

[0030] In the supporting plate pasting process, Figure 2As shown, a support plate 12 is attached to the first surface 2a of the semiconductor substrate 2. The support plate 12 is attached to the first surface 2a via an adhesive 11. The support plate 12 is made of, for example, glass. The adhesive 11 is, for example, a silicone adhesive. In addition to bonding the semiconductor substrate 2 to the support plate 12, it also protects the main structure 6 formed on the first surface 2a of the semiconductor substrate 2. Therefore, the adhesive 11 is applied so that its thickness is thicker than that of the main structure 6.

[0031] (Grinding process)

[0032] Then, if Figure 3 As shown, the second surface 2b of the semiconductor substrate 2 is ground using a grinding tool 31. Thus, the semiconductor substrate 2 is thinned. The thickness of the semiconductor substrate 2 before and after grinding is not particularly limited, and can be, for example, approximately 350 nm and approximately 100 nm, respectively.

[0033] (Silicide Layer Formation Step)

[0034] Next, execute Figure 4 and Figure 5 In the silicide layer forming process, first, as shown in FIG. Figure 4 As shown, a nickel layer 8 is formed on the second surface 2b of the semiconductor substrate 2. The nickel layer 8 is formed so as to cover substantially the entire area of ​​the second surface 2b. That is, the nickel layer 8 is formed on the second surface 2b so as to span a plurality of element regions 3. Next, the semiconductor substrate 2 is heat treated. As a result, the nickel in the nickel layer 8 reacts with the silicon in the semiconductor substrate 2. As a result, Figure 5 As shown, in the range where the nickel layer 8 contacts the semiconductor substrate 2 , a silicide layer 8 a formed by alloying nickel and silicon is formed.

[0035] (Metal Film Formation Process)

[0036] Next, implement Figure 6 The metal film forming step shown in FIG. In this metal film forming step, a multilayer film 9 composed of, for example, titanium, nickel, and gold is formed on the surface of the silicide layer 8a. The multilayer film 9 is formed to cover substantially the entire area of ​​the silicide layer 8a. In other words, the multilayer film 9 is formed on the silicide layer 8a so as to span across the plurality of device regions 3. Hereinafter, the silicide layer 8a and the multilayer film 9 are collectively referred to as the metal film 10. The metal film 10 functions as an electrode in the completed semiconductor device.

[0037] (Crack Formation Process)

[0038] Next, implement Figure 7The crack forming process shown. In the crack forming process, the scribing wheel 32 is pushed from the second surface 2b side of the semiconductor substrate 2 attached to the support plate 12. That is, in this process, the scribing wheel 32 is pushed against the surface of the metal film 10. As a result, the metal film 10 is divided along the predetermined dividing line 4, and a scribing line accompanied by a crack 5 is formed inside the semiconductor substrate 2. The scribing wheel 32 is a disk-shaped (annular) component that is rotatably supported on a supporting device (not shown). Here, the scribing wheel 32 is pushed against the surface of the metal film 10 while being moved (scanned) along the predetermined dividing line 4. When the scribing wheel 32 moves along the predetermined dividing line 4, it rolls on the surface of the metal film 10 without sliding, like a tire rolling on the road surface. Although the peripheral portion of the scribing wheel 32 is sharp, it is only pushed against the surface of the metal film 10. During this process, the scribing wheel 32 is pressed against the surface of the metal film 10 with a load sufficient to separate the metal film 10 and form cracks 5 in the semiconductor substrate 2. As the scribing wheel 32 presses against the surface of the metal film 10, compressive stress is generated within the semiconductor substrate 2, in the surface region of the second surface 2b. While a scribing line (i.e., a groove) is formed at the location where the scribing wheel 32 is pressed, tensile stress is generated within the semiconductor substrate 2 directly below the region where the compressive stress is generated. Directly below the region where the compressive stress is generated, tensile stress is generated along the second surface 2b of the semiconductor substrate 2 in a direction away from the intended separation line 4. This tensile stress forms cracks 5 within the semiconductor substrate 2, extending along the intended separation line 4 and in the thickness direction of the semiconductor substrate 2. Here, by moving the scribing wheel 32 along the intended separation line 4 while pressing against the surface of the metal film 10, the metal film 10 is separated along the boundary between adjacent device regions 3, and cracks 5 are formed along this boundary, extending in the thickness direction of the semiconductor substrate 2. Furthermore, since the semiconductor substrate 2 is fixed by the support plate 12 made of a relatively hard material, the metal film 10 can be divided and the cracks 5 can be formed with a relatively small load when the scribing wheel 32 is pressed against the semiconductor substrate 2. The scribing wheel 32 is an example of a "pressing member."

[0039] (Cutting and pasting process)

[0040] Next, implement Figure 8 In the dicing tape pasting step, the dicing tape 13 is pasted on the surface of the metal film 10. The dicing tape 13 is pasted in a manner that covers substantially the entire area of ​​the metal film 10. The dicing tape 13 is fixed to a dicing frame (not shown). In addition, it should be noted that Figure 8 Thereafter, the semiconductor substrate 2 is drawn with the first surface 2 a facing upward.

[0041] (Support Plate Peeling Process)

[0042] Next, implement Figure 9 The support sheet peeling step shown in FIG. In the support sheet peeling step, support sheet 12 and adhesive 11 are peeled from first surface 2a of semiconductor substrate 2. For example, adhesive 11 is dissolved using a solvent, and support sheet 12 and adhesive 11 are peeled from first surface 2a together. As a result, semiconductor substrate 2 is supported by dicing tape 13.

[0043] (Protective component covering process)

[0044] Next, implement Figure 10 The protective member covering step is shown. In this protective member covering step, a protective member 15 is affixed across the surfaces of each main structure 6 in each device region 3 of the semiconductor substrate 2, thereby covering the first surface 2a of the semiconductor substrate 2 with the protective member 15. The material of the protective member 15 is not particularly limited; for example, a resin can be used. Covering with the protective member 15 protects the first surface 2a of the semiconductor substrate 2 during subsequent steps such as the separation step.

[0045] (Separation process)

[0046] Next, implement Figure 11 The splitting process shown. In the splitting process, the cutting plate 33 is pushed along the predetermined splitting line 4 (the crack 5 formed in the crack forming process), and the semiconductor substrate 2 is split along the predetermined splitting line 4 (along the boundary of the element area 3). Here, first, the semiconductor substrate 2 is placed on two support tables 34. The two support tables 34 are arranged at a distance. When the semiconductor substrate 2 is placed on the support tables 34, the semiconductor substrate 2 is placed in a manner such that the corresponding distance is below the position to be split (the position where the cutting plate 33 is pushed). Thereafter, the breaking plate 33 is pushed against the first surface 2a of the semiconductor substrate 2 via the protective component 15. The cutting plate 33 is a plate-shaped component, and the lower end (the end edge pushed against the first surface 2a) portion becomes a ridgeline (sharp blade shape), but it does not cut the semiconductor substrate 2 but is only pushed.

[0047] Because there is no support platform 34 below the cutting plate 33 (there is a gap between the two support platforms 34), when the cutting plate 33 is pressed against the first surface 2a, the semiconductor substrate 2 bends so as to enter the gap between the two support platforms 34. Consequently, a crack 5 is formed on the second surface 2b side of the semiconductor substrate 2. Therefore, when the cutting plate 33 is pressed against the semiconductor substrate 2 from the first surface 2a side, the semiconductor substrate 2 bends about the pressed portion (line) as the axis, and a force is applied to the crack 5 on the second surface 2b side in a direction that pulls the two device regions 3 adjacent to the division position apart. Furthermore, as described above, tensile stress is applied around the crack 5. Therefore, when the cutting plate 33 is pressed against the first surface 2a, the crack 5 extends in the thickness direction of the semiconductor substrate 2, and the semiconductor substrate 2 is divided along the intended division line 4. Alternatively, instead of two support platforms 34, for example, a single elastic support plate (or one or more support platforms with an elastic support plate interposed therebetween) may support the entire second surface 2b of the semiconductor substrate 2. In this case, an elastic support plate is located below the cutting plate 33. However, when the semiconductor substrate 2 flexes, the elastic support plate deforms in accordance with the flexure of the semiconductor substrate 2. Therefore, when the cutting plate 33 is pressed against the first surface 2a, a force is applied to the crack 5 in a direction that pulls the two adjacent element regions 3 at the division position apart, similar to the case where the cutting plate 33 is supported by two support platforms 34 (the case where there is no support platform 34 below the cutting plate 33). The cutting plate 33 is an example of a "dividing member."

[0048] In the dividing step, the above-mentioned step of pressing the cutting plate 33 against the first surface 2a is repeatedly performed along each predetermined dividing line 4. As a result, the semiconductor substrate 2 can be divided along the boundary of each element region 3. The metal film 10 has already been divided along this boundary in the above-mentioned crack forming step. Therefore, by performing the dividing step, the semiconductor substrate 2 and the metal film 10 can be divided along the boundary of each element region 3. Thereafter, as shown in FIG. Figure 12 As shown, the singulated device regions 3 and metal film 10 are peeled off from the dicing tape 13. When peeling the singulated device regions 3 and metal film 10 from the dicing tape 13, the dicing tape 13 can be expanded (stretched) to peel the singulated device regions 3 and metal film 10 while being separated from each other. Thus, a plurality of semiconductor devices 20 having metal films 10 (electrodes) formed on their surfaces are completed.

[0049] As described above, in this embodiment, the metal film 10 is formed on the second surface 2b of the semiconductor substrate 2 while the support plate 12 is attached to the first surface 2a of the semiconductor substrate 2. Subsequently, the scribing wheel 32 is pressed against the surface of the metal film 10, thereby dividing the metal film 10 along the boundaries of the device regions 3 and forming cracks 5 within the semiconductor substrate 2. Since the metal film 10 is divided during the process of forming the cracks 5, the film stress applied to the semiconductor substrate 2 is low when the support plate 12 is peeled off from the semiconductor substrate 2. Consequently, warping of the semiconductor substrate 2 caused by the film stress of the metal film 10 is reduced. Therefore, the break plate 33 can be pressed against the semiconductor substrate 2 with high precision along the boundaries of the device regions 3, thereby suppressing the formation of cracks in the manufactured semiconductor device 20.

[0050] In this embodiment, after the support plate 12 is attached to the first surface 2a of the semiconductor substrate 2, the second surface 2b of the semiconductor substrate 2 is ground using the grinding tool 31. Therefore, the manufactured semiconductor device 20 can be miniaturized.

[0051] In this embodiment, the metal film 10 includes the silicide layer 8a formed at the interface with the second surface 2b of the semiconductor substrate 2. Therefore, when the metal film 10 functions as an electrode, the contact resistance between the metal film 10 and the semiconductor substrate 2 can be reduced.

[0052] In addition, in the above-described embodiment, the grinding step, the silicide layer forming step, the dicing tape attaching step, and the protective member covering step may not be performed.

[0053] While the above detailed descriptions of the embodiments are provided, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include technologies resulting from various modifications and alterations to the specific examples exemplified above. The technical elements described in this specification or the accompanying drawings exhibit technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies exemplified in this specification or the accompanying drawings may achieve multiple objectives simultaneously, and achieving one of these objectives alone may be considered technically useful.

Claims

1. A method for manufacturing a semiconductor device, characterized in that: Has the following processes: a step of attaching a support plate to a first surface of a semiconductor substrate having a plurality of device regions; After attaching the support plate, forming a metal film on a second surface located on the back side of the first surface, extending across the plurality of device regions; a step of pressing a pressing member on the surface of the metal film along a boundary of the element region, thereby dividing the metal film along the boundary and forming a crack in the semiconductor substrate extending along the boundary and in a thickness direction of the semiconductor substrate; a step of peeling the support plate from the first surface after the step of forming the crack; as well as and a step of pressing a dividing member toward the semiconductor substrate along the boundary from the first surface side to thereby divide the semiconductor substrate along the boundary.

2. The method for manufacturing a semiconductor device according to claim 1, wherein: After the step of attaching the support plate and before the step of forming the metal film, a step of grinding the second surface of the semiconductor substrate is further included.

3. The method for manufacturing a semiconductor device according to claim 1 or 2, wherein: The metal film includes a silicide layer formed at an interface between the metal film and the second surface of the semiconductor substrate.

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