Wafer substrate having adhesion improving region, wafer substrate with protective film layer, and wafer substrate manufacturing method having adhesion improving region

Abstract

The present invention aims to provide a wafer with a protective film layer, etc. that improves adhesion of the protective film layer to a wafer substrate subjected to various surface treatments and prevents solution intrusion. To achieve this aim, a wafer substrate with an adhesion improvement region (3) is used, which is a wafer substrate (1a) used to provide a protective film layer for impeding solution penetration on the surface, characterized by having a protective film layer adhesion improvement region (3) that improves adhesion of the protective film layer along the periphery of the wafer substrate subjected to various surface treatments.

Description

Technical Field

[0001] The present invention relates to a wafer substrate having an improved adhesion region, a wafer substrate with a protective film layer, and a method for manufacturing the wafer substrate. Background Technology

[0002] In the past, wafers were an indispensable material in semiconductor manufacturing, and the resulting electronic devices and components were widely used in all electronic and electrical products, including those in the automotive, digital home appliance, and communication equipment fields.

[0003] For example, in power semiconductors, electrodes are formed on the surface of a wafer substrate, and a metal film is formed on the entire back side. This back-side metal film is formed by methods such as vapor deposition or plating. Here, when plating the electrodes on the surface of the wafer substrate, a protective film, such as a protective film, is generally applied to the entire back side of the wafer substrate to protect the metal film from plating solutions, cleaning solutions, etc. However, generally, the adhesive used in the protective film has low adhesion to the metal film, resulting in solution seepage from the outer periphery of the wafer substrate into the space between the protective film and the wafer substrate. When solution seepage occurs during plating, it causes dissolution of the metal film and precipitation of the plating, leading to a decrease in product yield. Furthermore, it causes liquid and wafer contamination due to detachment of the deposited plating, and a decrease in the performance of the plating solution due to dissolution from the film. Moreover, if a resist is formed on the protective surface, it can cause the resist to peel off.

[0004] To address this problem, Patent Document 1 describes a method for manufacturing a semiconductor device. This method involves coating one side of a semiconductor substrate with a curable resin and then curing the resin after attaching the film, thereby preventing erosion by the plating solution and enabling plating to be performed on the other side of the semiconductor substrate.

[0005] Furthermore, in Patent Document 2, a method for manufacturing a semiconductor device is employed. This method involves attaching a protective film to the back of a wafer and then attaching a protective film to the sides, thereby stably attaching and peeling the protective film to the portions where no plating layer has been formed, and preventing abnormal precipitation of the plating layer.

[0006] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2010-182807 Patent Document 2: Japanese Patent Application Publication No. 2016-152317 Summary of the Invention The technical problem that the invention aims to solve However, in the inventions disclosed in Patent Documents 1 and 2, in addition to the film used to protect the main surface of the wafer, Patent Document 1 uses a curable resin to fix the film in order to prevent solution intrusion, and Patent Document 2 also attaches a protective tape to the outer periphery. Therefore, the following problems exist: increased costs associated with the apparatus for applying and peeling the curable resin, or the dedicated apparatus for attaching and peeling the protective tape, and the corresponding increase in the cost of the protective film used. Furthermore, attaching the protective tape requires applying constant pressure with rollers, which may be difficult to manage in the case of wafer thinning due to the risk of breakage.

[0007] Therefore, the object of the present invention is to provide a wafer substrate with a protective film layer, which improves the adhesion of the protective film layer of the wafer substrate that has undergone various surface treatments without using the protective tape described above, and can prevent the intrusion of liquid medicine even without the protective tape.

[0008] Solutions for solving technical problems In order to solve the above-mentioned problems, the inventors of this invention, through dedicated research, came up with the following invention.

[0009] The wafer substrate with improved adhesion region of this application is a wafer substrate used to form a protective film layer on its surface to prevent solution penetration. Surface treatment is performed by methods such as evaporation, sputtering, and plating. This surface treatment results in the outermost layer being a metal film composed of precious metals such as gold and silver, and is layered with titanium, chromium, copper, and their alloys. Furthermore, the wafer substrate with improved adhesion region is characterized by having a protective film layer improved adhesion region parallel to the outer peripheral end of the wafer substrate that has undergone various surface treatments.

[0010] In the wafer substrate with improved adhesion region of this application, it is preferable that the improved adhesion region is a region in which at least gold, silver, platinum, or palladium, which are precious metal components, are absent from the inorganic components used in the surface treatment.

[0011] In the wafer substrate with improved adhesion region of this application, it is more preferable that the improved adhesion region is a region where there are no inorganic components used in the surface treatment and the wafer surface is exposed.

[0012] In the wafer substrate with an improved adhesion region of this application, the improved adhesion region preferably has a strip-shaped region with a width of 0.2 mm or more and 3 mm or less, which is parallel to the outer periphery of the planar wafer substrate.

[0013] In the wafer substrate with an improved adhesion region of this application, the improved adhesion region preferably has a strip-shaped region with a width of 0.2 mm or more and W1 mm ​​or less from the outer peripheral end of the wafer substrate when the width of the strip-shaped protrusion is set to W1 mm.

[0014] The wafer substrate with a protective film layer of this application is characterized in that a protective film layer is provided on the surface of the wafer substrate having the above-mentioned improved adhesion region to improve the barrier effect against solution penetration.

[0015] The present application discloses a method for manufacturing a wafer substrate with an improved adhesion region: The method for manufacturing a wafer substrate with an improved adhesion region as described above is characterized in that the surface is physically ground or cut parallel to the outer peripheral end of the wafer substrate to which various surface treatments have been applied, and the metal layer or all of the metal layer that constitutes part of the surface treatment layer located on the outer periphery of the wafer surface is peeled off, thereby forming an improved adhesion region. The surface treatment layer is a layer formed by evaporation, sputtering, plating, or other methods, in which the outermost surface is a metal film made of precious metals such as gold and silver, and is laminated with titanium, chromium, copper, and their alloys.

[0016] In the wafer substrate manufacturing method with an improved adhesion region of this application, when the improved adhesion region is provided on the outer periphery of a planar wafer substrate, it is preferable to perform physical grinding or cutting on a surface portion with a width of 0.2 mm or more and 3 mm or less parallel to the outer periphery end of the wafer substrate to form a strip-shaped region.

[0017] In the wafer substrate manufacturing method with an improved adhesion region of this application, when the improved adhesion region is provided on the outer periphery of a wafer substrate having a strip-shaped protrusion with a raised shape along the outer periphery, when the width of the strip-shaped protrusion is set to W1mm, it is preferable to perform physical grinding or cutting on a surface portion with a width of 0.2mm or more and W1mm or less parallel to the outer periphery end of the wafer substrate to form a strip-shaped region.

[0018] In the wafer substrate manufacturing method with improved adhesion region of this application, the grinding depth during the grinding process is preferably 20nm to 10μm.

[0019] Invention Effects According to the present invention, by having a protective film adhesion enhancement region parallel to the outer peripheral end of a wafer substrate that has undergone various surface treatments, the penetration of the protective film layer into the space between the back of the wafer and the protective film can be effectively prevented. Furthermore, the adhesion enhancement region, provided parallel to the outer peripheral end of the wafer substrate, can be easily formed by grinding or cutting. Film application and peeling can be performed using existing equipment, requiring minimal equipment investment and enabling the provision of high-quality wafer products at low cost. By employing the invention of this application, the conventional method of attaching protective tape to the periphery is eliminated, thus suppressing excessive equipment investment and rising material costs. Attached Figure Description

[0020] Figure 1 Three views of a wafer substrate with a planar adhesion enhancement region are shown schematically.

[0021] Figure 2 Three views are shown schematically of a wafer substrate having a band-shaped protrusion with an improved adhesion region along its outer periphery.

[0022] Figure 3 A schematic diagram of a processing apparatus used for grinding a surface treatment layer located at the outer periphery of a wafer to form an area with improved adhesion.

[0023] Figure 4 This is a schematic diagram illustrating a state in which no solution intrusion occurs between the protective film and the wafer substrate when the improved adhesion region is present (Example), and a state in which solution intrusion occurs between the protective film and the wafer substrate when the improved adhesion region is not present (Comparative Example). Detailed Implementation

[0024] The following describes the wafer substrate with an improved adhesion region, the wafer substrate with a protective film, and the manufacturing method of the wafer substrate with the improved adhesion region according to the present invention. Furthermore, the wafer substrate is a substrate formed of a compound semiconductor such as silicon or silicon carbide.

[0025] 1. Implementation method of a wafer substrate having an improved adhesion region The wafer substrate with improved adhesion region of this application is used by providing a protective film layer on its surface to prevent solution penetration. Generally, wafer substrates undergo various surface treatments during use. Among these surface treatments, multilayered inorganic components such as gold, silver, and nickel are widely used. Therefore, the protective film adhered to the wafer substrate is bonded to it through this surface treatment layer. In this state, the adhesion of the protective film is insufficient. Therefore, an improved adhesion region is provided parallel to the outer peripheral edge of the wafer substrate to enhance the adhesion of the protective film layer.

[0026] The adhesion enhancement region is a region in which surface treatment components that hinder the adhesion of the protective film layer are removed, parallel to the outer peripheral end of the wafer substrate where the surface treatment layer is formed. The adhesion enhancement region is expected to be established based on the following technical concept.

[0027] The adhesion-enhancing region of the wafer substrate is preferably a region free of precious metals such as gold, silver, platinum, and palladium, which are at least noble metals in the inorganic components used in the surface treatment. This is because precious metal components are most likely to cause instability in the adhesion of the protective film.

[0028] Furthermore, even if the adhesion enhancement region with the removal of precious metal components is provided as described above, the adhesion of the protective film at the outer peripheral end of the wafer is still insufficient. More preferably, the adhesion enhancement region is formed by completely removing the inorganic components used in the surface treatment located in the outer peripheral region of the wafer substrate, thus exposing the wafer surface in the outer peripheral region. Because by completely removing the components used in the surface treatment layer, reliable adhesion between the protective film and the wafer substrate is obtained, and solution ingress is reliably prevented.

[0029] In a wafer substrate having this improved adhesion region, the improved adhesion region disposed on the outer periphery of the planar wafer substrate is preferably a strip-shaped region with a width of 0.2 mm or more and 3 mm or less (hereinafter referred to as "adhesion width") parallel to the outer periphery end of the wafer substrate. When the adhesion width is less than 0.2 mm, the adhesion of the protective film is unstable and cannot completely prevent solution intrusion. On the other hand, even if the adhesion width exceeds 3 mm, the improvement effect of the protective film does not increase, and therefore it is not ideal.

[0030] Figure 1 Three views of a wafer substrate 1a with a planar adhesion enhancement region are shown. Figure 1 It can be seen that a protective film layer adhesion enhancement region 4, which improves the adhesion of the protective film layer 3, is provided parallel to the outer periphery of the silicon wafer substrate 2. Furthermore, in Figure 1 The description of the surface treatment layer with a thickness of tens of nm to several μm is omitted in the three-view diagram shown.

[0031] Furthermore, when the wafer substrate with the improved adhesion region is a wafer substrate having a raised strip-shaped portion along its outer periphery (referring to the so-called "TAIKO" shape), the improved adhesion region can be configured as follows: When the width of the raised strip-shaped portion in its protruding state is set to W1mm, it is preferable to define the improved adhesion region as a strip-shaped region with a width of 0.2mm or more and W1mm or less, parallel to the outer periphery of the wafer substrate. When the adhesion width is less than 0.2mm, the adhesion of the protective film is unstable and cannot completely prevent solution intrusion, which is undesirable. On the other hand, if the adhesion width exceeds the width W1mm of the raised strip-shaped portion along the outer periphery of the wafer substrate, the adhesion of the protective film to the wafer substrate becomes unstable, which is also undesirable.

[0032] Figure 2 This image shows a three-view diagram of a wafer substrate 1b with an improved adhesion region, in the case of a wafer substrate 1b having a strip-shaped protrusion along its outer periphery (referring to a so-called "TAIKO" shape). Figure 2 It can be seen that a protective film layer adhesion enhancement region 4, which improves the adhesion of the protective film layer 3, is provided parallel to the outer peripheral end of the wafer substrate 2. Furthermore, in Figure 2 The description of the surface treatment layer with a thickness of tens of nm to several μm is omitted in the three-view diagram shown.

[0033] The wafer substrate with a protective film layer: The wafer substrate with a protective film layer of this application is characterized in that a protective film layer is provided on the surface of the wafer substrate having the improved adhesion region to prevent solution from penetrating between the wafer substrate and the protective film. The bonding of the protective film to the wafer substrate can be achieved using any known method, such as roller bonding or vacuum bonding.

[0034] The method for manufacturing a wafer substrate with an improved adhesion region: The method for manufacturing a wafer substrate with an improved adhesion region described in this application is the method for manufacturing a wafer substrate with an improved adhesion region as described above. Therefore, based on the above, it can be understood that by controlling the surface treatment components located on the surface of the wafer substrate, a wafer substrate with an improved adhesion region that prevents the penetration of solution between the wafer substrate and the protective film is manufactured.

[0035] From the perspective of removing the surface treatment layer on the wafer surface, several methods can be considered. These include: (1) applying a surface treatment layer in areas that enhance adhesion by either coating with a resist or covering them with a fixture to prevent plating precipitation; (2) removing the surface treatment layer by wet etching only on the outer periphery of the wafer substrate after surface treatment; and (3) removing the surface treatment layer only on the outer periphery of the wafer substrate by dry etching based on argon ions after surface treatment. However, any of these methods incurs excessive equipment investment and low operational efficiency.

[0036] Therefore, the present invention adopts the following method: by grinding or cutting the surface along the outer periphery of the wafer substrate that has undergone various surface treatments, the metal layer or all of the metal layer that constitutes part of the surface treatment layer located on the outer periphery of the wafer surface is peeled off, thereby forming a region with improved adhesion.

[0037] Figure 3 This diagram illustrates a processing apparatus used for physical grinding or cutting to process a surface treatment layer located at the outer periphery of a wafer substrate to form an area with improved adhesion.

[0038] In the case of a wafer substrate 1a with a planar adhesion enhancement region using such a device, the adhesion enhancement region 4, which improves the adhesion of the protective film layer 3 disposed on the outer periphery of the wafer substrate 1a, is formed by physical grinding or cutting of a strip-shaped region, wherein the strip-shaped region has an adhesion width of 0.2 mm or more and 3 mm or less, parallel to the outer periphery end of the wafer substrate 2. The reason for determining the adhesion width is the same as described above.

[0039] Furthermore, in the case of a wafer substrate 1b having an improved adhesion region, and in the case of a wafer substrate 2 having a strip-shaped protrusion with a raised shape along its outer periphery, when the width of the protruding strip-shaped protrusion in the protruding state is W1 mm, it is also preferable to form the protective film layer improved adhesion region 3 by physically grinding or cutting a strip-shaped region with an adhesion width of 0.2 mm or more and W1 mm ​​or less, parallel to the outer periphery end of the wafer substrate 2. The reason for determining the adhesion width is the same as described above.

[0040] In the wafer substrate manufacturing method with an improved adhesion region according to this application, the grinding or cutting depth during the grinding or cutting process is not particularly limited in principle, as long as the surface treatment components that hinder the adhesion of the protective film are removed. However, in practice, 20 nm to 10 μm is preferred. When the grinding or cutting depth is less than 20 nm, residual metal components that hinder the adhesion of the protective film remain, which is not ideal. This is because even if the grinding or cutting depth exceeds 10 μm, the wafer surface is exposed and the adhesion of the protective film is not further improved.

[0041] Furthermore, the wafer substrate with improved adhesion region of this application can be used in various wafer backside protection methods, such as the protection method using a protective strip with a single-sided adhesive layer, or the method using a double-sided strip and protecting the wafer with a glass wafer.

[0042] The embodiments of the present invention described above are merely one approach, and appropriate modifications can be made without departing from the spirit of the invention. Furthermore, the following examples provide a more detailed description of the invention, but the invention is not limited to these examples.

[0043] Example 1 An 8-inch diameter silicon wafer substrate with a pre-formed surface treatment layer was prepared. This surface treatment layer was a multi-layer titanium / nickel / gold plating (with gold as the outermost layer) formed by sputtering. It was then mounted on... Figure 3 The grinding apparatus shown grinds the outer peripheral end, removing only the outermost gold layer to obtain a silicon wafer substrate with an improved adhesion region.

[0044] A protective film was bonded to the back side of the silicon wafer substrate with the improved adhesion region using two methods (roller bonding and vacuum bonding) to obtain a silicon wafer substrate with a protective film. Then, a solution permeation test was performed on the silicon wafer substrate with the protective film. The test procedure is shown in Table 1. Furthermore, the results are shown in Table 2 for comparison with comparative examples.

[0045] [Table 1]

[0046] Example 2 An 8-inch diameter silicon wafer substrate with a pre-formed surface treatment layer, identical to that in Example 1, was prepared. The surface treatment layer here is a multilayer titanium / nickel / gold plating (outermost layer being gold) formed by sputtering. It was then mounted on... Figure 3 The grinding apparatus shown grinds the outer peripheral end to completely remove the surface treatment layer, resulting in a silicon wafer substrate with an improved adhesion region.

[0047] A protective film was bonded to the back side of the silicon wafer substrate with the improved adhesion region using two methods (roller bonding and vacuum bonding) to obtain a silicon wafer substrate with a protective film. Then, a solution permeation test was performed on the silicon wafer substrate with the protective film. The test procedure is shown in Table 1. Furthermore, the results are shown in Table 2 for comparison with comparative examples.

[0048] Example 3 An 8-inch diameter silicon wafer substrate with a pre-formed surface treatment layer and raised bands along its outer periphery was prepared. The surface treatment layer at this stage was a multilayer titanium / nickel / gold plating (outermost layer being gold) formed by sputtering. It was then mounted on... Figure 3 The grinding apparatus shown grinds the outer peripheral end, removing only the outermost gold layer, to obtain a silicon wafer substrate with a band-shaped protrusion having an improved adhesion area.

[0049] A protective film was bonded to the back side of the silicon wafer substrate with the improved adhesion region using two methods (roller bonding and vacuum bonding) to obtain a silicon wafer substrate with a protective film. Then, a solution permeation test was performed on the silicon wafer substrate with the protective film. The test procedure is shown in Table 1. Furthermore, the results are shown in Table 2 for comparison with comparative examples.

[0050] Example 4 An 8-inch diameter silicon wafer substrate with a raised stripe shape along its outer periphery and a pre-formed surface treatment layer was prepared. The surface treatment layer at this stage was a multi-layer titanium / nickel / gold plating (with gold as the outermost layer) formed by sputtering. It was then mounted on... Figure 3 The grinding apparatus shown grinds the outer peripheral end to completely remove the surface treatment layer, resulting in a silicon wafer substrate with a band-shaped protrusion having an improved adhesion area.

[0051] A protective film was bonded to the back side of the silicon wafer substrate with the improved adhesion region using two methods (roller bonding and vacuum bonding) to obtain a silicon wafer substrate with a protective film. Then, a solution permeation test was performed on the silicon wafer substrate with the protective film. The test procedure is shown in Table 1. Furthermore, the results are shown in Table 2 for comparison with comparative examples.

[0052] Comparative example In the comparative example, a silicon wafer substrate with a pre-formed surface treatment layer and an 8-inch diameter, identical to that in Example 1, was prepared. The surface treatment layer was a multilayer titanium / nickel / gold plating (with gold as the outermost layer) formed by sputtering, resulting in a silicon wafer substrate with a residual surface treatment layer without forming an adhesion-enhancing region.

[0053] A protective film was bonded to the back of the silicon wafer substrate using two methods (roller bonding and vacuum bonding) to obtain a silicon wafer substrate with a protective film. Then, a solution permeation test was performed on the silicon wafer substrate with the protective film. The test procedure is shown in Table 1. Furthermore, the results are shown in Table 2 in a manner that allows for comparison with the examples.

[0054] 〔evaluate〕 The following shows the comparison results between Examples 1 to 4 and the comparative examples. The evaluation results are summarized in Table 2.

[0055] [Table 2]

[0056] As shown in Table 2, in Examples 1 to 4, where the improved adhesion region is present, no solution intrusion occurred between the protective film and the silicon wafer substrate. In contrast, it can be understood that solution intrusion occurred between the protective film and the silicon wafer substrate in the comparative examples. It should be noted that the differences are not considered to be due to variations in the protective film lamination method.

[0057] Furthermore, based on the number of wafer damage sites shown in Table 2 and Figure 4 The schematic diagrams show that in Examples 1 to 4, where the sealing enhancement area is provided, no solution intrusion occurs between the protective film and the silicon wafer substrate. In contrast, it is clearly understood that in the comparative example, solution intrusion occurs between the protective film and the silicon wafer substrate, resulting in significant defects.

[0058] Industrial availability By using this invention, high-quality chip products can be provided at low cost. As a result, products using high-quality power semiconductors and other chips can be provided at an appropriate price. Furthermore, the manufacturing method employed in this application does not require excessive equipment investment, which is also an advantage.

[0059] Explanation of reference numerals in the attached figures 1a, 1b: Wafer substrate with improved adhesion region 2: Semiconductor devices 3: Areas with improved sealing 4: Belt-driven rotary grinding machine

Claims

1. A wafer substrate having an improved adhesion region, wherein a protective film layer for preventing solution penetration is provided on the surface of the wafer substrate, characterized in that, A protective film adhesion enhancement region is provided parallel to the outer periphery of the wafer substrate that has undergone various surface treatments, thereby improving the adhesion of the protective film layer.

2. The wafer substrate having an improved adhesion region according to claim 1, wherein, The area where the improved adhesion is located is a region where at least one of the inorganic components used in the surface treatment—gold, silver, platinum, or palladium—is a precious metal.

3. The wafer substrate with an improved adhesion region according to claim 1, wherein, The area where the improved adhesion is located is the area where there are no inorganic components used in the surface treatment and where the wafer surface is exposed.

4. The wafer substrate having an improved adhesion region according to claim 1, wherein, The adhesion enhancement region disposed on the outer periphery of a planar wafer substrate is a strip-shaped region having a width of 0.2 mm or more and 3 mm or less, parallel to the outer periphery of the wafer substrate.

5. The wafer substrate having an improved adhesion region according to claim 1, wherein, The improved adhesion region, which is provided on the outer periphery of a wafer substrate having a strip-shaped protrusion with a raised shape along its outer periphery, is a strip-shaped region having a width of 0.2 mm or more and W1 mm ​​or less, parallel to the outer periphery of the wafer substrate when the width of the strip-shaped protrusion is W1 mm.

6. A wafer substrate with a protective film layer, characterized in that, A protective film layer is provided on the surface of the wafer substrate having an improved adhesion region as described in any one of claims 1 to 5 to improve the barrier effect against solution penetration.

7. A method for manufacturing a wafer with an improved adhesion region, comprising a method for manufacturing a wafer substrate with an improved adhesion region as described in any one of claims 1 to 5, characterized in that... By cutting or grinding the surface parallel to the outer periphery of the wafer that has undergone various surface treatments, the metal layer that constitutes part of the surface treatment layer near the outer periphery of the wafer surface is peeled off, thereby forming an area with improved adhesion.

8. The wafer manufacturing method with an improved adhesion region according to claim 7, wherein, When the adhesion enhancement region is provided on the outer periphery of a planar wafer substrate, a strip-shaped region is formed by cutting or grinding with a width of 0.2 mm or more and 3 mm or less parallel to the outer periphery of the wafer substrate.

9. The wafer manufacturing method with an improved adhesion region according to claim 7, wherein, When the improved adhesion region is provided on the outer periphery of a wafer substrate having a strip-shaped protrusion with a raised shape along the outer periphery, and the width of the strip-shaped protrusion is set to W1mm, a width of 0.2mm or more and W1mm or less is cut or ground parallel to the outer periphery of the wafer substrate to form the strip-shaped region.

10. The method according to any one of claims 7 to 9, wherein, The cutting depth during the cutting or grinding process is 20 nm to 10 μm.

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