Method for manufacturing semiconductor device

Abstract

In this method for manufacturing a semiconductor device, prepared first is a substrate 10 that includes a support substrate 11, conducting sections 12 disposed on the support substrate 11, and a polyimide film 13 disposed on the support substrate 11 and the conducting sections 12. In the prepared substrate 10, the polyimide film 13 includes: a first portion 13a that covers a front surface of the support substrate 11 and side surfaces of the conducting sections 12; and a second portion 13b that is located on the first portion 13a and covers an upper surface of the conducting sections 12. In this method for manufacturing a semiconductor device, after at least part of the second portion 13b is cut away by fly-cutting while leaving the first portion 13a, the front surface of the polyimide film 13 is polished. This makes it possible to shorten labor time in a polishing step and easily reduce the surface roughness of the substrate 10. This substrate 10 can be used, for instance, for hybrid bonding.

Description

Semiconductor device manufacturing method

[0001] The present disclosure relates to a method for manufacturing a semiconductor device.

[0002] In recent years, three-dimensional packaging has been considered to improve the integration density of LSIs. Non-Patent Document 1 discloses an example of three-dimensional packaging of semiconductor chips.

[0003] FC Chen et al., “System on Integrated Chips(SoIC TM) for 3D Heterogeneous Integration”, 2019 IEEE 69th Electronic Components and Technology Conference (ECTC), p.594-599(2019)

[0004] When fabricating semiconductor devices using three-dimensional packaging, hybrid bonding techniques that directly bond two devices have been considered to allow for finer wiring between devices. However, if the device substrate surface is rough, poor bonding may occur during hybrid bonding. Specifically, the greater the substrate surface roughness, the lower the bonding strength between devices. Therefore, methods have been considered to flatten the substrate surface by cutting it using a fly-cutting method or polishing it. However, while cutting the substrate surface using a fly-cutting method alone can achieve high-speed flattening, it is difficult to sufficiently reduce surface roughness. While polishing the substrate surface alone can reduce surface roughness, the polishing process requires a long time. Therefore, a method for manufacturing a semiconductor device that can easily reduce surface roughness is desired.

[0005] An object of the present disclosure is to provide a method for manufacturing a semiconductor device that can easily reduce surface roughness.

[0006] [1] One aspect of the present disclosure relates to a method for manufacturing a semiconductor device, the method for manufacturing a semiconductor device comprising the steps of: preparing a substrate having a support substrate, a conductive portion provided on the support substrate, and an insulating film provided on the support substrate and the conductive portion, the insulating film having a first portion covering a surface of the support substrate and a side surface of the conductive portion, and a second portion located on the first portion and covering an upper surface of the conductive portion; cutting at least a part of the second portion by a fly-cutting method while leaving the first portion; and polishing the surface of the insulating film, the polishing step being performed after the cutting step.

[0007] In this manufacturing method, at least a portion of the second portion covering the upper surface of the conductive portion is cut by a fly-cutting method while leaving a first portion covering the surface of the support substrate and the side surface of the conductive portion, and then the surface of the insulating film is polished. In this case, part of the polishing step can be replaced by the cutting step. This makes it possible to reduce surface roughness while shortening the processing time in the polishing step. Therefore, according to the manufacturing method of the semiconductor device described above in [1], surface roughness can be easily reduced.

[0008] [2] In the semiconductor device manufacturing method of [1] above, in the cutting step, the second portion may be cut so that at least a portion of the second portion remains. In the polishing step, the remaining portion of the cut second portion may be polished so that the surface of the first portion and the upper surface of the conductive portion are flush with each other. When the above-mentioned planarization is performed, the conductive portion that will become an electrode may extend, causing a change in shape of the conductive portion. If the shape of the conductive portion that will become an electrode changes, there is a risk of poor bonding during hybrid bonding. However, according to the semiconductor device manufacturing method of [2] above, it is possible to prevent the shape of the conductive portion from changing, thereby preventing poor bonding during subsequent hybrid bonding.

[0009] [3] In the method for manufacturing a semiconductor device according to [1] above, in the cutting step, the second portion may be cut so that the surface of the first portion and the upper surface of the conductive portion are flush with each other. In the polishing step, the surface of the first portion is polished. In this case, it is possible to further reduce the working time of the polishing step while reducing the surface roughness. Therefore, according to the method for manufacturing a semiconductor device according to [3] above, it is possible to further reduce the surface roughness.

[0010] [4] In the method for manufacturing a semiconductor device according to any one of [1] to [3] above, in the polishing step, the surface of the cut insulating film may be polished by a CMP method. According to the method for manufacturing a semiconductor device according to [4] above, the polishing step can be carried out easily. Furthermore, the surface roughness of the insulating film surface can be more reliably reduced.

[0011] [5] The method for manufacturing a semiconductor device according to any one of [1] to [4] above may further include the steps of preparing a substrate having a separate support substrate, a separate conductive portion provided on the separate support substrate, and a separate insulating film provided on the separate support substrate and the separate conductive portion, and bonding the substrate to the separate substrate after the polishing step. In this case, for the reasons described above, the substrate and the separate substrate are bonded together with the surface roughness of the substrate reduced. Therefore, the method for manufacturing a semiconductor device according to [5] above can improve the bonding strength between the substrate and the separate substrate.

[0012] FIG. 1 illustrates an example of a semiconductor device manufactured by a semiconductor device manufacturing method according to an embodiment of the present disclosure. FIG. 2 is a cross-sectional view illustrating a method for manufacturing a semiconductor device according to an embodiment of the present disclosure, illustrating an example of a step of preparing a substrate. FIG. 3 is a cross-sectional view illustrating a method for manufacturing a semiconductor device according to an embodiment of the present disclosure, illustrating an example of a step of cutting a second portion of an insulating film by a flycutting method. FIG. 4 is a cross-sectional view illustrating a method for manufacturing a semiconductor device according to an embodiment of the present disclosure, illustrating an example of a step of polishing a surface of the cut insulating film. FIG. 5 is a cross-sectional view illustrating a method for manufacturing a semiconductor device according to an embodiment of the present disclosure, illustrating an example of a step of bonding a substrate to another substrate. FIG. 6 is a cross-sectional view illustrating a method for manufacturing a semiconductor device according to an embodiment of the present disclosure, illustrating another example of a step of cutting a second portion of an insulating film by a flycutting method.

[0013] Hereinafter, several embodiments of the present disclosure will be described in detail, with reference to the drawings as necessary. In the following description, identical or equivalent parts will be designated by the same reference numerals, and redundant explanations will be omitted. Furthermore, positional relationships such as up, down, left, right, etc. will be based on the positional relationships shown in the drawings unless otherwise specified. When terms such as "left," "right," "front," "back," "top," "bottom," "upper," and "lower" are used in the description and claims of this specification, these terms are intended for explanatory purposes and do not necessarily mean that these relative positions will always be the same. Furthermore, the dimensional ratios of the drawings are not limited to those shown. Furthermore, in this specification, the term "process" includes not only independent processes, but also processes that cannot be clearly distinguished from other processes as long as the intended effect of the process is achieved.

[0014] (Configuration of Semiconductor Device) First, with reference to FIG. 1 , the configuration of a semiconductor device 1 manufactured by the semiconductor device manufacturing method according to this embodiment will be described. FIG. 1 shows an example of a semiconductor device manufactured by the semiconductor device manufacturing method according to this embodiment. As shown in FIG. 1 , the semiconductor device 1 is, for example, an example of a semiconductor package, and includes a plurality of electrodes 2, an insulating film 3, a substrate 10, and a substrate 20. The electrode 2 is formed by bonding a conductive portion 12 of the substrate 10 to a conductive portion 22 of the substrate 20 (see FIG. 5 ), which will be described later. The insulating film 3 is formed by bonding an insulating film 13 (first portion 13 a) of the substrate 10 to an insulating film 23 (first portion 23 a) of the substrate 20 (see FIG. 5 ), which will be described later. In the semiconductor device 1, the substrate 10 and the substrate 20 are bonded together. The substrate 10 may include a semiconductor element. The semiconductor element included in the substrate 10 may be located on the surface opposite the substrate 20 when the substrates 10 and 20 are bonded together. The substrate 20 may also include a semiconductor element. The semiconductor element included in the substrate 20 may be disposed on the surface opposite to the substrate 10 when the substrates 10 and 20 are bonded together. The semiconductor elements included in the substrates 10 and 20 are, for example, semiconductor chips such as LSI (Large Scale Integrated Circuit) chips, CMOS (Complementary Metal Oxide Semiconductor) sensors, memories, etc. The semiconductor elements included in the substrates 10 and 20 may also be other types of semiconductor chips.

[0015] (Method of Manufacturing Semiconductor Device) Next, a method of manufacturing the semiconductor device 1 will be described with reference to FIGS. 2 to 5. FIG. 2 is a cross-sectional view for explaining the method of manufacturing the semiconductor device according to this embodiment, showing an example of a step of preparing a substrate. FIG. 3 is a cross-sectional view for explaining the method of manufacturing the semiconductor device according to this embodiment, showing an example of a step of cutting the second portion of the insulating film by a flycut method. FIG. 4 is a cross-sectional view for explaining the method of manufacturing the semiconductor device according to this embodiment, showing an example of a step of polishing the surface of the cut insulating film. FIG. 5 is a cross-sectional view for explaining the method of manufacturing the semiconductor device according to this embodiment, showing an example of a step of bonding the substrate to another substrate.

[0016] The semiconductor device 1 can be manufactured, for example, through the following steps (a) to (g). That is, the manufacturing method of the semiconductor device 1 includes the following steps (a) to (g): a) a step of preparing a substrate having a support substrate, a conductive portion provided on the support substrate, and an insulating film provided on the support substrate and on the conductive portion, the insulating film having a first portion covering the surface of the support substrate and the side surfaces of the conductive portion, and a second portion located on the first portion and covering the top surface of the conductive portion; b) a step of cutting at least a part of the second portion by a fly-cutting method while leaving the first portion; and c) a step of polishing the surface of the insulating film, which is a step performed after step (b). (d) a step of preparing a substrate having another support substrate, another conductive portion provided on the other support substrate, and another insulating film provided on the other support substrate and the other conductive portion, and, after a polishing step, a step of bonding the substrate to the other substrate, wherein the other insulating film has a first portion covering the surface of the support substrate and the side surfaces of the conductive portion, and a second portion located on the first portion and covering the upper surface of the conductive portion; (e) a step of cutting at least a part of the second portion by a flycutting method while leaving the first portion; (f) a step of polishing the surface of the insulating film, which is a step performed after step (e); and (g) a step of bonding the substrate to the other substrate, which is a step performed after steps (c) and (f).

[0017] The step g) of bonding a substrate to another substrate includes the following steps: g1) bonding an insulating film of a substrate to another insulating film of another substrate, and g2) bonding a conductive portion of a substrate to another conductive portion of another substrate.

[0018] [Step (a)] Step (a) is a step of preparing the substrate 10. To prepare the substrate 10, first, a support substrate 11 having a conductive portion 12 and an insulating film 13 is prepared. For example, the support substrate 11 is a silicon wafer. The support substrate 11 is, for example, a silicon wafer having a thickness of 0.2 mm or more and 2.0 mm or less. The diameter of the support substrate 11 is, for example, 200 mm, 300 mm, or 450 mm. Alternatively, the support substrate 11 may be a substrate including a glass plate, a SUS plate, or a glass cloth plate, or may be a resin substrate that encapsulates a semiconductor element. The support substrate 11 may be a panel-shaped substrate. In this case, the support substrate 11 is, for example, a rectangular panel with one side measuring 300 mm or more and 700 mm or less. The support substrate 11 may have another configuration.

[0019] In the substrate 10 prepared in step (a), the conductive portion 12 is provided on the support substrate 11. Such conductive portion 12 is provided on the support substrate 11 using, for example, a photosensitive material. In this case, the conductive portion 12 is provided on the support substrate 11, for example, as follows. First, a base layer is provided on the support substrate 11. This base layer serves as a seed during electrolytic plating, which will be described later. Next, a resist layer is provided on the base layer. In one example, a film-like insulating material is attached to the support substrate 11 by lamination processing as the resist layer.

[0020] This lamination process is carried out, for example, at a temperature set to 40°C or higher and 120°C or lower. For this reason, it is preferable to use a photosensitive insulating film that can be laminated at 40°C or higher and 120°C or lower as the film-like insulating material. By setting the lamination temperature to 40°C or higher, it is possible to prevent the tack (adhesiveness) of the photosensitive insulating film from becoming strong at room temperature, and to maintain good handleability of the photosensitive insulating film. By setting the lamination temperature of the photosensitive insulating film to 120°C or lower, it is possible to prevent warping of the photosensitive insulating film after the lamination process. Note that "room temperature" refers to approximately 25°C.

[0021] Next, the resist layer is exposed to light and developed to form openings in the resist layer. In this embodiment, a plurality of openings are formed in the resist layer corresponding to the plurality of electrodes 2. Specifically, a predetermined exposure is performed with a photomask placed on the resist layer to form a pattern corresponding to the conductive portions 12. The exposed resist layer is then developed using a developer. This dissolves the unexposed portions of the resist layer, forming a plurality of openings. At this time, the base layer is exposed in the plurality of openings.

[0022] Next, conductive portions 12 are provided so that at least a portion thereof is located within the plurality of openings. In one example, the conductive portions 12 are formed by electrolytic plating using the base layer exposed in the plurality of openings as a seed layer. The conductive portions 12 are formed so that at least a portion thereof is located within the plurality of openings. In this case, the plurality of openings are filled with, for example, copper plating to form the conductive portions 12.

[0023] Next, the resist layer is peeled off from the support substrate 11. The peeling is carried out using a commonly used peeling liquid.

[0024] The conductive portion 12 provided by the above method is composed of a copper pillar having a diameter of, for example, 0.5 μm or more and 20 μm or less. Furthermore, the volume resistivity of the conductive portion 14 is, for example, 40 μΩ·cm or less from the viewpoint of transmission efficiency. From the viewpoint of suppressing the amount of heat generation, the volume resistivity is preferably 30 μΩ·cm or less. Furthermore, from the viewpoint of reliability, the volume resistivity is more preferably 20 μΩ·cm or less. The volume resistivity is typically 3 μΩ·cm or more.

[0025] In the substrate 10 prepared in step (a), the insulating film 13 is provided on the support substrate 11 and the conductive portion 12. Such an insulating film 13 is provided, for example, by applying a liquid organic insulating material onto the surface of the support substrate 11 and the surface of the conductive portion 12 by spin coating.

[0026] The organic insulating material is, for example, polyimide, a polyimide precursor, polyamideimide, benzocyclobutene (BCB), polybenzoxazole (PBO), or a PBO precursor.

[0027] Furthermore, in the substrate 10 prepared in step (a), the insulating film 13 has a first portion 13a and a second portion 13b. The first portion 13a covers the surface of the support substrate 11 and the side surfaces of the conductive portion 12. The second portion 13b is located on the first portion 13a and covers the upper surface of the conductive portion 12. The thickness of the second portion 13b is, for example, not less than 1 μm and not more than 20 μm. The first portion 13a and the second portion 13b are provided integrally.

[0028] The thickness of the insulating film 13 formed on the support substrate 11 is, for example, 10 μm or less, preferably 5 μm or less, and more preferably 3 μm or less. The thickness of the insulating film 13 may also be 1 μm or more. The thickness of the insulating film 13 is, for example, the sum of the thickness of the first portion 13 a and the thickness of the second portion 13 b. The insulating film 13 may also be made of an inorganic material.

[0029] After the insulating film 13 is provided, the insulating film 13 may be heated and cured. In this case, the heating temperature may be, for example, 100° C. or higher and 400° C. or lower, and the heating time may be, for example, 30 minutes or higher and 3 hours or lower.

[0030] 2 , a substrate is prepared that includes a support substrate 11, a conductive portion 12 provided on the support substrate 11, and an insulating film 13 provided on the support substrate 11 and the conductive portion 12. Therefore, it can be said that the step (a) includes the steps of providing an underlayer on the support substrate 11, providing a resist layer on the underlayer, providing an opening in the resist layer by exposing and developing the resist layer, providing the conductive portion 12 so that at least a portion of the conductive portion 12 is located in the opening, and providing the insulating film 13 on the support substrate 11 and the conductive portion 12.

[0031] [Step (b)] Step (b) is a step of cutting the insulating film 13. In step (b), the insulating film 13 is cut by a fly-cutting method. In one example, a first portion 13a of the insulating film 13 that covers the surface of the support substrate 11 and the side surfaces of the conductive portion 12 is left, while a second portion 13b that covers the upper surface of the conductive portion 12 is cut by the fly-cutting method.

[0032] In step (b) of this embodiment, as shown in FIG. 3 , the second portion 13b is cut by a flycutting method so that the surface of the second portion 13b protrudes from the upper surface of the conductive portion 12 (so that a portion of the second portion 13b remains). That is, in step (b) of this embodiment, the thickness of the second portion 13b is reduced by the flycutting method. Therefore, in step (b) of this embodiment, it can be said that a portion of the second portion 13b is removed by cutting. The thickness of the second portion 13b cut by the flycutting method is, for example, 0.5 μm or more and 20 μm or less. Therefore, at the end of step (b) of this embodiment, the thickness of the second portion 13b is, for example, 3.0 μm or more and 10 μm or less.

[0033] In the fly-cutting method, a grinding device 100 using, for example, a diamond tool is used. In this case, as shown in FIG. 3, the grinding device 100 is moved in a predetermined direction above the substrate 10 to cut the second portion 13b. A specific example of the grinding device 100 is an automatic surface planer (manufactured by Disco Corporation, product name "DAS8930") compatible with 300 mm wafers. The cutting of the second portion 13b by the fly-cutting method can also be considered a planarization process. In addition, in step (b), etching or the like may be combined with the fly-cutting method.

[0034] At the end of step (b) in this embodiment, the surface roughness of the second portion 13b cut by the flycutting method is, for example, 10 nm or more and 100 nm or less. In this embodiment, the surface roughness is the arithmetic mean roughness (Ra) defined in JIS B 0601 2001. The surface roughness of the second portion 13b after cutting is measured, for example, by scanning a 100 μm × 100 μm area including the second portion 13b using a laser microscope ("LEXT OLS3000" manufactured by Olympus Corporation).

[0035] [Step (c)] Step (c) is a step of polishing the surface of the insulating film 13, and is a step performed after the grinding in step (b). In step (c) of this embodiment, as shown in FIG. 4 , the remaining portion of the cut second portion 13b is polished so that the surface of the first portion 13a and the upper surface of the conductive portion 12 are flush with each other. More specifically, by polishing the surface of the remaining portion of the cut second portion 13b, the second portion 13b remaining after step (b) is removed, and the surface of the first portion 13a and the upper surface of the conductive portion 12 are flush with each other. In step (c) of this embodiment, after the surface of the first portion 13a and the upper surface of the conductive portion 12 are flush with each other, the surface of the first portion 13a and the upper surface of the conductive portion 12 are further polished.

[0036] The above-described polishing can be performed using a grinder for electronic materials processing or a chemical mechanical polishing (CMP) method. In step (c) of this embodiment, the surface of the second portion 13b is polished by the CMP method. For the CMP method, for example, a polishing device 110 is used. In this case, as shown in FIG. 4 , the polishing device 110 is pressed against the surface of the second portion 13b and rotated, thereby polishing the surface of the second portion 13b through mechanical friction between the polishing liquid applied to the surface of the polishing device 110 and the second portion 13b. The above-described polishing of the surface of the second portion 13b by the CMP method can also be considered a planarization process.

[0037] At the time when step (c) in this embodiment is completed, the surface roughness of the first portion 13a is, for example, 0.5 nm or more and 3.0 nm or less due to the polishing described above. The surface roughness of the upper surface of the conductive portion 12 is, for example, 0.5 nm or more and 3.0 nm or less. The surface roughness is the arithmetic mean roughness (Ra) defined in JIS B 0601 2001. The surface roughness of the first portion 13a after polishing and the surface roughness of the upper surface of the conductive portion 12 are measured, for example, by the same method as that for the surface roughness of the second portion 13b after cutting.

[0038] [Step (d)] Step (d) is a step of preparing a substrate 20 different from the substrate 10. In step (d), a substrate 20 is prepared, which includes a support substrate 21, a conductive portion 22 provided on the support substrate 21, and an insulating film 23 provided on the support substrate 21 and the conductive portion 22. In the substrate 20 prepared in step (d), the insulating film 23 has a first portion 23a covering the surface of the support substrate 21 and the side surface of the conductive portion 22, and a second portion 23b located on the first portion 23a and covering the upper surface of the conductive portion 22. The method for preparing the substrate 20 is similar to the method for preparing the substrate 10, and detailed description thereof will be omitted. However, the substrate 20 is prepared through the steps described above. The substrate 20 does not need to have exactly the same configuration as the substrate 10. The thickness or material of the support substrate 21, the thickness or material of the insulating film 23, etc. may be different from those of the substrate 10.

[0039] [Step (e)] Step (e) is a step of cutting second portion 23b. The method of cutting second portion 23b is similar to the method of cutting second portion 13b, and therefore detailed description will be omitted. However, second portion 23b is cut through the steps shown in Fig. 3. In step (e), second portion 23b may be cut so that the surface of second portion 23b protrudes from the upper surface of conductive portion 22.

[0040] [Step (f)] Step (f) is a step of polishing the surface of the insulating film 23, and is a step performed after step (e). The method of polishing the surface of the insulating film 23 is similar to the method of polishing the surface of the insulating film 13, and therefore detailed description will be omitted. However, the surface of the insulating film 23 is cut through the steps shown in Fig. 4. In step (f), the surface of the second portion 23b may be polished so that the surface of the first portion 23a and the upper surface of the conductive portion 22 are flush with each other.

[0041] [Step (g)] Step (g) is a step of bonding substrate 10 and substrate 20, and is performed after steps (c) and (f). In step (g), first, insulating film 13 of substrate 10 and insulating film 23 of substrate 20 are bonded. Here, at least one of substrate 10 and substrate 20 is aligned so that conductive portion 12 of substrate 10 and conductive portion 22 of substrate 20 face each other. Both substrate 10 and substrate 20 may be aligned. For such alignment, an alignment mark or the like may be provided on at least one of substrate 10 and substrate 20.

[0042] When bonding the substrates 10 and 20, organic substances or metal oxides adhering to the surfaces of the substrates 10 and 20 are removed, and then the substrate 20 is aligned with the substrate 10. After the alignment is complete, the first portion 13a of the insulating film 13 and the first portion 23a of the insulating film 23 are bonded together by hybrid bonding. At this time, the first portion 13a and the first portion 23a may be uniformly heated before bonding. By bonding the first portion 13a and the first portion 23a, the insulating film 3 of the semiconductor device 1 is formed, as shown in FIG. 1 .

[0043] The temperature difference between the substrate 10 and the substrate 20 during bonding is preferably, for example, 10°C or less. By heat bonding at such a uniform temperature, the insulating film 13 is mechanically and firmly attached to the insulating film 23. Furthermore, because heat bonding is performed at a uniform temperature, positional deviation at the bonding point is unlikely to occur, and high-precision bonding can be performed. Note that the substrates 10 and 20 may be bonded together by other bonding methods, such as room-temperature bonding.

[0044] Next, after the bonding of the insulating film 13 of the substrate 10 and the insulating film 13 of the substrate 20 is completed, the conductive portion 12 of the substrate 10 and the conductive portion 22 of the substrate 20 are bonded. In this embodiment, as shown in FIG. 5 , after the bonding of the insulating film 13 and the insulating film 23 is completed, a predetermined amount of heat and / or pressure is applied to bond the conductive portion 12 and the conductive portion 22 by hybrid bonding. When the conductive portion 12 and the conductive portion 22 are made of copper, the annealing temperature here is preferably 150° C. or higher and 400° C. or lower, and more preferably 200° C. or higher and 300° C. or lower. This bonding process results in an electrode 2 in which the conductive portion 12 and the conductive portion 22 are bonded, and the electrode 2 in which the conductive portion 12 and the conductive portion 22 are mechanically and electrically firmly bonded is formed. Note that the electrode bonding may be performed after the bonding of the insulating film 13 and the insulating film 23, or may be performed simultaneously with the bonding of the insulating film 13 and the insulating film 23.

[0045] Through the above steps, the semiconductor device 1 shown in FIG. 1 is manufactured.

[0046] As described above, according to the manufacturing method of the semiconductor device 1 of this embodiment, in step (b), a portion (a large portion) of the second portion 13b covering the upper surface of the conductive portion 12 is cut by a fly-cutting method while leaving the first portion 13a covering the surface of the support substrate 11 and the side surfaces of the conductive portion 12, and then the surface of the insulating film 13 is polished. In this case, part of step (c) can be replaced by step (b). This makes it possible to reduce the surface roughness while shortening the working time in step (c). Therefore, according to the manufacturing method of the semiconductor device 1, the surface roughness can be easily reduced.

[0047] When the substrate surface is planarized, the conductive portion 12 that will become the electrode 2 may extend, causing a change in shape of the conductive portion 12. If the shape of the conductive portion 12 changes, there is a risk of poor bonding during hybrid bonding. In the manufacturing method of the semiconductor device 1, in step (b), the second portion 13b is cut so that at least a portion of the second portion 13b remains. In step (c), the surface of the second portion 13b is polished so that the surface of the first portion 13a and the upper surface of the conductive portion 12 are flush with each other. According to the manufacturing method of the semiconductor device 1, it is possible to prevent the shape of the conductive portion 12 from changing, thereby preventing poor bonding during subsequent hybrid bonding.

[0048] In the manufacturing method of the semiconductor device 1, in step (c), the ground surface of the insulating film 13 is polished by a CMP method. According to the manufacturing method of the semiconductor device 1, step (c) can be easily performed. Furthermore, the surface roughness of the surface of the insulating film 13 can be more reliably reduced.

[0049] The method for manufacturing the semiconductor device 1 includes a step (d) of preparing a substrate 20 having a support substrate 21, a conductive portion 22 provided on the support substrate 21, and an insulating film 23 provided on the support substrate 21 and the conductive portion 22, and a step (g) of bonding the substrate 10 and the substrate 20 after the step (d). In this case, for the reasons described above, the substrate 10 and the substrate 20 are bonded together with the surface roughness of the substrate 10 reduced. Therefore, the method for manufacturing the semiconductor device 1 can improve the bonding strength between the substrate 10 and the substrate 20.

[0050] Next, a modified example of the method for manufacturing the semiconductor device 1 will be described with reference to Fig. 6. Fig. 6 is a cross-sectional view for explaining the modified example of the method for manufacturing the semiconductor device according to the present embodiment, showing another example of the step of cutting the second portion of the insulating film by the fly-cutting method.

[0051] 6, in step (b), the second portion 13b is cut by the fly-cutting method so that the surface of the first portion 13a is flush with the upper surface of the conductive portion 12. That is, in step (b) of this modified example, it can be said that the entire second portion 13b is removed by cutting by the fly-cutting method.

[0052] In the fly-cutting method, similarly to the above-described embodiment, a grinding device 100 using, for example, a diamond tool is used. In this case, too, the second portion 13b is cut by moving the grinding device 100 in a predetermined direction above the substrate 10, as shown in FIG.

[0053] At the time when step (b) in this modified example is completed, the surface roughness of the first portion 13a, which has been cut by the flycutting method to be flush with the upper surface of the conductive portion 12, is, for example, 10 nm or more and 100 nm or less. In this modified example, the surface roughness is the arithmetic mean roughness (Ra) defined in JIS B 0601 2001. In this modified example, the surface roughness of the first portion 13a after cutting is measured by scanning a 100 μm × 100 μm area including the insulating film 13 using, for example, a laser microscope ("LEXT OLS3000" manufactured by Olympus Corporation).

[0054] As described above, in step (b) of this modified example, the entire second portion 13b is removed by cutting using the flycutting method. Therefore, in step (c) of this modified example, the surface of the first portion 13a is polished. In step (c) of this modified example, in addition to the surface of the first portion 13a, the upper surface of the conductive portion 12 may also be polished.

[0055] At the time when step (c) in this modified example is completed, the surface roughness of the first portion 13a is, for example, 0.5 nm or more and 3.0 nm or less due to the polishing described above. Furthermore, the surface roughness of the upper surface of the conductive portion 12 is, for example, 0.5 nm or more and 3.0 nm or less. The surface roughness is the arithmetic mean roughness (Ra) defined in JIS B 0601 2001. The surface roughness of the first portion 13a after polishing and the surface roughness of the upper surface of the conductive portion 12 are measured, for example, by the same method as that for the surface roughness of the second portion 13b after cutting.

[0056] In this modification, in step (b), the second portion 13b is cut so that the surface of the first portion 13a is flush with the upper surface of the conductive portion 12. In this case, it is possible to further reduce the work time in step (b) while reducing the surface roughness. Therefore, according to this modification, it is possible to reduce the surface roughness even more easily.

[0057] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0058] Example 1: A substrate corresponding to the substrate 10 in the above-described embodiment was prepared, which included a support substrate, a conductive portion provided on the support substrate, and a polyimide film provided on the support substrate and the conductive portion. The conductive portion was provided by electrolytic copper plating. In the prepared substrate, the polyimide film had a portion covering the surface of the support substrate and the side surface of the conductive portion, and a portion located on the portion and covering the upper surface of the conductive portion. Furthermore, in the prepared substrate, the elastic modulus of the polyimide film was 2.55 (GPa).

[0059] Next, the polyimide film was cut by a fly-cutting method so that at least a portion of the polyimide film covering the top surface of the conductive portion remained, while the portion of the polyimide film covering the surface of the support substrate and the side surfaces of the conductive portion remained. Next, the surface of the remaining cut portion of the polyimide film was polished by a CMP method so that the surface of the polyimide film was flush with the top surface of the conductive portion.

[0060] Thereafter, a laser microscope (Olympus Corporation, "LEXT OLS3000") was used to scan a 100 μm × 100 μm area on the substrate surface to measure the substrate surface roughness (arithmetic mean roughness (Ra) as defined in JIS B 0601 2001). The substrate surface roughness refers to the surface roughness of the substrate when the surface of the polyimide film and the upper surface of the conductive portion are flush with each other, and includes the surface roughness of the polyimide film and the upper surface of the conductive portion in this state. Furthermore, with the polyimide film and the conductive portion captured in the image field, an image of the substrate was acquired from a direction perpendicular to the thickness direction of the substrate, and the acquired image was inspected for the presence or absence of extension of the conductive portion. As a result, in Example 1, the substrate surface roughness was 1.5 nm, and no extension of the conductive portion was confirmed.

[0061] In Example 2, a substrate similar to that in Example 1 was prepared. Next, the portion of the polyimide film covering the upper surface of the conductive portion was cut by fly-cutting so that the surface of the polyimide film was flush with the upper surface of the conductive portion, while leaving the portion of the polyimide film covering the surface of the support substrate and the side surfaces of the conductive portion. Next, the cut surface of the polyimide film and the upper surface of the conductive portion were polished by CMP.

[0062] Thereafter, the surface roughness of the substrate was measured to check whether the conductive portion had extended in the same manner as in Example 1. As a result, in Example 2, the surface roughness of the substrate was 1.5 nm, and the extension of the conductive portion was confirmed.

[0063] [Comparative Example 1] In Comparative Example 1, a substrate similar to that in Example 1 was prepared. Next, the portion of the polyimide film covering the upper surface of the conductive portion was cut using the same method as in Example 1. In Comparative Example 1, the surface of the polyimide film was not polished using the CMP method. That is, in Comparative Example 1, only the polyimide film was cut using the flycut method.

[0064] Thereafter, the surface roughness of the substrate was measured to check whether the conductive portion had extended in the same manner as in Example 1. As a result, in Comparative Example 1, the surface roughness of the substrate was 133 nm, and the extension of the conductive portion was confirmed.

[0065] [Comparative Example 2] In Comparative Example 2, a substrate similar to that in Example 1 was prepared. Next, the portion of the polyimide film covering the upper surface of the conductive portion was polished by CMP so that the surface of the polyimide film was flush with the upper surface of the conductive portion, while leaving the portion of the polyimide film covering the surface of the support substrate and the side surface of the conductive portion. In Comparative Example 2, the polyimide film was not cut by the flycut method. That is, in Comparative Example 2, only the surface of the polyimide film was polished by CMP.

[0066] Thereafter, the surface roughness of the substrate was measured to check whether the conductive portion had extended in the same manner as in Example 1. As a result, in Comparative Example 2, the surface roughness of the substrate was 1.5 nm, and the extension of the conductive portion was confirmed.

[0067] When performing general hybrid bonding, it is desirable that the surface roughness of the substrate be 10 nm or less. Therefore, in evaluating the surface roughness of the substrates in Experimental Examples 1 and 2 and Comparative Examples 1 and 2, if the surface roughness of the substrate was 10 nm or less, it was evaluated as "good (A)," and if the surface roughness of the substrate was more than 10 nm, it was evaluated as "fail (F)."

[0068] In Example 1, the surface roughness of the substrate was 1.5 nm, so Example 1 was evaluated as "A." In Example 2, the surface roughness of the substrate was 1.5 nm, so Example 2 was evaluated as "A." In Comparative Example 1, the surface roughness of the substrate was 133 nm, so Comparative Example 1 was evaluated as "F." In Comparative Example 2, the surface roughness of the substrate was 1.5 nm, so Comparative Example 2 was evaluated as "A."

[0069] The results of Examples 1 and 2 and Comparative Examples 1 and 2 are summarized in Table 1 below.

[0070] First, let us focus on the surface roughness. As shown in Table 1, Example 1, Example 2, and Comparative Example 2, in which the polyimide film was cut by the flycutting method and then the surface of the polyimide film was polished by CMP, were rated as "A" for surface roughness. On the other hand, Comparative Example 1, in which the surface of the conductive portion was not polished by CMP, was rated as "F" for surface roughness. Therefore, it can be seen that the surface roughness of the substrate can be reduced when the polyimide film (insulating film) is cut by the flycutting method and then the surface of the polyimide film (insulating film) is polished by CMP.

[0071] Next, we will focus on the extension of the conductive portion. As shown in Table 1, no extension of the conductive portion was observed in Example 1. Therefore, it can be seen that if, in the step of cutting the polyimide film (insulating film), the portion of the polyimide film covering the upper surface of the conductive portion is cut by the fly-cutting method so that at least a portion of that portion remains, extension of the conductive portion can be suppressed and deformation of the conductive portion can be prevented. As a result, it can be seen that, in the step of cutting the polyimide film (insulating film), if the portion of the polyimide film covering the upper surface of the conductive portion is cut by the fly-cutting method so that at least a portion of that portion remains, bonding defects during hybrid bonding can be more reliably suppressed. Note that, with regard to Example 2, in which extension of the conductive portion was confirmed, it was considered possible to use the substrate for hybrid bonding by removing the extended portion of the conductive portion, for example, before the step of bonding the substrate to another substrate.

[0072] Furthermore, when the surface roughness of the substrate is 10 nm or less and no extension of the conductive portion is confirmed, it is expected that the bondability during hybrid bonding will be good. Therefore, when the polyimide film (insulating film) is cut by the fly-cutting method in the step of cutting the polyimide film (insulating film), the portion of the polyimide film covering the upper surface of the conductive portion is cut so that at least a portion of that portion remains, it is expected that the bondability during hybrid bonding will be good.

[0073] When comparing the flycutting method and the CMP method, the thickness of the polyimide film (insulating film) removed per unit time by the flycutting method tends to be greater than the same thickness by the CMP method. Therefore, when removing the same thickness of polyimide film, the time required by the flycutting method is expected to be shorter than the time required by the CMP method. That is, the processing time in Examples 1 and 2, in which the polyimide film was cut by the flycutting method and then polished by the CMP method, is expected to be shorter than the processing time in Comparative Example 2, in which the polyimide film was only polished by the CMP method. Therefore, it is understood that by replacing part of the process of polishing the polyimide film by the CMP method with the process of cutting the polyimide film by the flycutting method, the processing time in the polishing process can be shortened.

[0074] Although the embodiments of the present disclosure have been described above, the present invention is not limited to the above-described embodiments, and appropriate modifications may be made without departing from the spirit of the present disclosure.

[0075] In the above embodiment, the conductive portions 12, 22 are formed by electrolytic plating, but this is not limiting. For example, the conductive portions 12, 22 may be formed by at least one of sputtering and electroless plating. Alternatively, the conductive portions 12, 22 may be formed by combining at least one of sputtering, electroplating, and electroless plating with a copper paste application process and a sintering process.

[0076] 10, 20...substrate, 11, 21...support substrate, 12, 22...conductive portion, 13, 23...insulating film, 13a, 23a...first portion, 13b, 23b...second portion.

Claims

1. A method for manufacturing a semiconductor device, comprising: a step of preparing a substrate having a supporting substrate, a conductive portion provided on the supporting substrate, and an insulating film provided on the supporting substrate and on the conductive portion, the insulating film having a first portion covering a surface of the supporting substrate and side surfaces of the conductive portion, and a second portion located on the first portion and covering an upper surface of the conductive portion; a step of cutting at least a portion of the second portion by a fly-cutting method while leaving the first portion; and a step of polishing a surface of the insulating film, the polishing step being performed after the cutting step.

2. The method for manufacturing a semiconductor device as described in claim 1, wherein in the cutting step, the second portion is cut so that at least a part of the second portion remains, and in the polishing step, the remaining part of the cut second portion is polished so that the surface of the first portion and an upper surface of the conductive portion are flush with each other.

3. The method for manufacturing a semiconductor device according to claim 1, wherein in the cutting step, the second portion is cut so that a surface of the first portion and an upper surface of the conductive portion are flush with each other, and in the polishing step, the surface of the first portion is polished.

4. The method for manufacturing a semiconductor device according to claim 1, wherein in the polishing step, the surface of the cut insulating film is polished by a CMP method.

5. A method for manufacturing a semiconductor device according to any one of claims 1 to 4, further comprising the steps of: preparing a substrate having another supporting substrate, another conductive portion provided on the another supporting substrate, and another insulating film provided on the another supporting substrate and on the another conductive portion; and bonding the substrate and the another substrate after the polishing step.

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