Method for manufacturing semiconductor device, and film-like adhesive

Abstract

This method for manufacturing a semiconductor device includes preparing a semiconductor member 10 having solder bumps 13 and minute copper pillars 12 which are micro-bumps on a semiconductor wafer 11. A non-conductive film (NCF) 20 is laminated on the semiconductor member 10 so as to cover the copper pillars 12 and the solder bumps 13. In this lamination, the NCF 20 is configured to be thicker than the heights of connection parts 14 formed of the copper pillars 12 and the solder bumps 13. Thereafter, the thick NCF 20 is ground by CMP to make surfaces 13a of the solder bumps 13 flush with a surface 20c of the NCF 20A. With this method, even when the NCF is applied to the micro-bumps, the thickness variation of the NCF and the remnant of a void can be suppressed. Furthermore, deformation of the micro-bumps during lamination can be suppressed.

Description

Semiconductor device manufacturing method and film-like adhesive

[0001] The present disclosure relates to a method for manufacturing a semiconductor device and a film-like adhesive.

[0002] Flip-chip bonding is known, in which conductive protrusions called bumps are formed on a semiconductor chip to directly connect the semiconductor chip to a wiring circuit board. Attempts have been made to use such flip-chip bonding to form multi-tiered semiconductor chips, such as four-tiered, eight-tiered, and twelve-tiered, and as a result, the bumps tend to be smaller in height and diameter (see, for example, Non-Patent Documents 1 and 2).

[0003] Julia Woertink et.al., “From C4 to micro-bump: Adapting lead free solder electroplating processes to next-gen advanced packaging applications”, 2014 Electronic Components and Technology Conference, pp.342-347, 2014.Mi-Seok Park et.al, “Effects of the degradation of methane sulfonic acid electrolyte on the collapse failure of Sn-Ag alloy solders for flip-chip interconnections”, The Royal Society of Chemistry 2017, pp.23136-23142, 2017.

[0004] As the height of the bumps decreases, the non-conductive resin film (NCF) used for flip-chip bonding tends to become thinner. However, simply thinning the resin film to match the bump height results in an extremely thin resin film, which is prone to thickness variations and voids that tend to remain when the resin film is laminated onto a semiconductor substrate (e.g., a semiconductor wafer). This reduces the manufacturing yield of semiconductor devices. Furthermore, because the bumps are small, laminating the extremely thin resin film can deform the bumps, potentially resulting in problems during mounting. On the other hand, laminating a resin film that is thicker than the bump height onto the semiconductor substrate to prevent such problems can result in an excess of resin on the connection portions of the solder bumps, which can lead to resin jamming during mounting or excessive fillets.

[0005] An object of the present disclosure is to provide a method for manufacturing a semiconductor device and a film-like adhesive that can improve the manufacturing yield of semiconductor devices.

[0006] [1] In one aspect, the present disclosure provides a method for manufacturing a semiconductor device. The method includes the steps of preparing a bonded structure including a semiconductor substrate, a connection portion provided on a main surface of the semiconductor substrate, and a film adhesive provided on the main surface of the semiconductor substrate so as to cover the connection portion, and grinding the film adhesive of the bonded structure. In this manufacturing method, the film adhesive is thicker than the height of the connection portion in the preparation step.

[0007] In this semiconductor device manufacturing method, a film-like adhesive thicker than the height of the connection portions is prepared in the preparation process, and then ground in the grinding process. In this case, thickness variations in the film-like adhesive applied to the main surface of the semiconductor substrate can be suppressed, and voids can be suppressed. Furthermore, bump deformation can be suppressed. Meanwhile, portions of the film-like adhesive that are unnecessary for mounting are ground away, thereby suppressing problems during mounting. Therefore, this semiconductor device manufacturing method can improve the manufacturing yield of semiconductor devices even when the connection portions are miniaturized. In addition, this semiconductor device manufacturing method uses a film-like adhesive thicker than the height of the connection portions, including the bumps, and the thickness is adjusted by grinding the film-like adhesive. This eliminates the need to individually prepare film-like adhesive members according to the height of the miniaturized connection portions. For example, it is possible to accommodate many types of connection portions using one or several types of film-like adhesive members with different thicknesses.

[0008] [2] In the semiconductor device manufacturing method of [1] above, it is preferable that the film adhesive has a thickness of at least 1.2 times the height of the connection portion in the preparation step. In this case, it is possible to more reliably suppress variations in the thickness of the film adhesive provided on the main surface of the semiconductor substrate, more reliably suppress the remaining of voids, and more reliably suppress deformation of the bumps.

[0009] [3] In the semiconductor device manufacturing method of [1] above, it is preferable that the film adhesive has a thickness of at least 1.5 times the height of the connection portion in the preparation step. In this case, it is possible to more reliably suppress variations in the thickness of the film adhesive provided on the main surface of the semiconductor substrate, more reliably suppress the remaining of voids, and more reliably suppress deformation of the bumps.

[0010] [4] In the method for manufacturing a semiconductor device according to any one of [1] to [3] above, the connection portion includes a connection terminal provided on the main surface of the semiconductor substrate and a bump provided on the connection terminal, and in the grinding step, it is preferable to grind the film-like adhesive so that the surface of the bump and the surface of the film-like adhesive are flush with each other. In this case, portions of the film-like adhesive that are not required for mounting can be more reliably ground, and problems during mounting can be suppressed.

[0011] [5] In any of the semiconductor device manufacturing methods [1] to [4] above, the film adhesive may have a thickness of 20 μm or more in the preparation step, and the film adhesive may be ground to a thickness of 10 μm or less in the grinding step. In this case, thickness variations in the film adhesive provided on the main surface of the semiconductor substrate can be more reliably suppressed, and residual voids can be more reliably suppressed. Furthermore, deformation of the bumps can be more reliably suppressed. Meanwhile, since portions of the film adhesive unnecessary for mounting are ground away, defects during mounting can be more reliably suppressed.

[0012] [6] The method for manufacturing a semiconductor device according to any one of [1] to [5] above may further include a step of curing the film adhesive of the bonded body before the grinding step. Because the film adhesive is viscous and may be soft, such a curing step makes it possible to more reliably grind the film adhesive.

[0013] [7] In any of the semiconductor device manufacturing methods described above in [1] to [6], the step of preparing the bonded body may include the steps of preparing a semiconductor member having a semiconductor substrate and a connection portion, and attaching a film adhesive to the semiconductor substrate so as to cover the connection portion of the semiconductor member. The film adhesive is preferably thicker than the height of the connection portion at least after being attached to the semiconductor substrate. Note that the film adhesive may already be thicker than the height of the connection portion before being attached to the semiconductor substrate.

[0014] [8] In the semiconductor device manufacturing method of [7] above, the film-like adhesive may have a protective film provided on the surface opposite to the surface attached to the semiconductor substrate, and the step of preparing the bonded body may include a step of grinding the back surface opposite to the main surface of the semiconductor substrate while the film-like adhesive with the protective film provided covers the connection portion, and a step of peeling off the protective film after the step of grinding the semiconductor substrate and before the step of grinding the film-like adhesive. In this case, the semiconductor substrate can be thinned to a predetermined thickness without deforming or damaging the microbumps. Furthermore, when peeling off the protective film from the film-like adhesive, it is possible to prevent a portion of the film-like adhesive from peeling off along with the protective film.

[0015] [9] In the semiconductor device manufacturing method according to any one of [1] to [8] above, in the step of grinding the film adhesive, it is preferable to grind the film adhesive using at least one of a grinder, a surface planer, and a CMP device. In this case, the film adhesive can be more reliably ground.

[0016]

[10] In the method for manufacturing a semiconductor device according to any one of the above [1] to [9], the film adhesive preferably contains an epoxy resin, a curing agent, and a fluxing agent.

[0017]

[11] The method for manufacturing a semiconductor device according to any one of [1] to

[10] above may further include the steps of: grinding the film adhesive and then singulating the bonded body into a plurality of semiconductor chips; and mounting at least one of the plurality of semiconductor chips on a substrate.

[0018]

[12] In another aspect, the present disclosure provides a film adhesive. The film adhesive is used in a semiconductor device manufacturing method including the steps of: preparing a bonded body having a semiconductor substrate, connection portions provided on a main surface of the semiconductor substrate, and a film adhesive provided on the main surface of the semiconductor substrate so as to cover the connection portions; and grinding the film adhesive of the bonded body. In the preparation step, the film adhesive is configured to be thicker than the height of the connection portions.

[0019] This film-like adhesive is configured to be thicker than the height of the connection portion during the preparation process. That is, this film-like adhesive is thicker than the height of the connection portion before the grinding process. In this case, it is possible to suppress variations in the thickness of the film-like adhesive provided on the main surface of the semiconductor substrate and also to suppress the remaining of voids. Furthermore, it is possible to suppress deformation of the bumps. Meanwhile, since the portions of the film-like adhesive that are not required for mounting are ground off, defects during mounting can also be suppressed. Therefore, by using this film-like adhesive, it is possible to improve the manufacturing yield of semiconductor devices even when the connection portion is miniaturized.

[0020]

[13] The film adhesive of

[12] above preferably has a thickness of at least 1.2 times the height of the connection portion during the preparation process. In this case, it is possible to more reliably suppress variations in the thickness of the film adhesive provided on the main surface of the semiconductor substrate, and it is also possible to more reliably suppress the remaining of voids. Furthermore, it is also possible to more reliably suppress deformation of the bump.

[0021]

[14] The film adhesive of

[12] above preferably has a thickness at least 1.5 times the height of the connection portion during the preparation process. In this case, it is possible to more reliably suppress variations in the thickness of the film adhesive provided on the main surface of the semiconductor substrate, and it is also possible to more reliably suppress the remaining of voids. Furthermore, it is also possible to more reliably suppress deformation of the bump.

[0022]

[15] The film adhesive according to any one of the above

[12] to

[14] preferably contains an epoxy resin, a curing agent, and a fluxing agent.

[0023] According to the present disclosure, the manufacturing yield of semiconductor devices can be improved.

[0024] Fig. 1 is a schematic cross-sectional view showing an example of a method for manufacturing a semiconductor device. Fig. 2 is a schematic cross-sectional view showing an example of a method for manufacturing a semiconductor device. Fig. 3 is a schematic cross-sectional view showing an example of a method for manufacturing a semiconductor device. Fig. 4 is a schematic cross-sectional view showing a comparative example of a method for manufacturing a semiconductor device.

[0025] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, the same or equivalent parts will be denoted by the same reference numerals, and duplicate explanations will be omitted. Furthermore, unless otherwise specified, positional relationships such as up, down, left, and right will be based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0026] In this specification, the term "layer" includes not only a structure having a shape formed over the entire surface when observed in a plan view, but also a structure having a shape formed on a portion thereof. In this specification, the term "process" includes not only an independent process, but also a process that cannot be clearly distinguished from other processes as long as the intended effect of the process is achieved.

[0027] In this specification, numerical ranges indicated using "to" indicate ranges that include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit of a numerical range in one stage may be replaced with the upper or lower limit of a numerical range in another stage. In numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in the examples.

[0028] A method for manufacturing a semiconductor device according to this embodiment will be described with reference to Figures 1 to 3. Figures 1, 2 and 3 are schematic cross-sectional views sequentially illustrating the method for manufacturing a semiconductor device.

[0029] First, as shown in FIG. 1A, a semiconductor member 10 is prepared, which includes a semiconductor substrate 11 and a plurality of connection terminals 12 (first connection portions) and a plurality of bumps 13 (second connection portions) provided on a main surface 11a of the semiconductor substrate 11. The semiconductor substrate 11 is, for example, an elemental semiconductor composed of the same type of element, such as silicon or germanium, or a semiconductor substrate including a compound semiconductor, such as gallium arsenide or indium phosphide. In this embodiment, the semiconductor substrate 11 is described as a semiconductor wafer, but the semiconductor substrate 11 may also be a semiconductor chip. The thickness of the semiconductor substrate 11 is, for example, 10 μm to 800 μm.

[0030] Each of the bumps 13 is provided on a corresponding connection terminal 12. The connection terminals 12 and the bumps 13 can be, for example, metal layers containing one or more metals selected from gold, silver, copper, solder, nickel, tin, and lead. The main component of the solder may be, for example, tin-silver, tin-lead, tin-bismuth, tin-copper, or tin-silver-copper. The metal constituting the connection terminals 12 and the bumps 13 may be gold, silver, copper, or solder, or may be silver, copper, or solder, or may be solder. The connection terminals 12 and the bumps 13 may be metal layers formed by plating. The connection terminals 12 and the bumps 13 may be a single layer or may include multiple metal layers. As an example, the connection terminals 12 may be copper pillars, and the bumps 13 may be solder bumps.

[0031] The diameter of each of the connection terminals 12 and the bumps 13 may be, for example, 20 μm or less, or 10 μm or less. The overall height of the connection portion 14 including both the connection terminals 12 and the bumps 13 may be, for example, 10 μm or less, 7 μm or less, or 5 μm or less. The pitch (meaning the center pitch) between adjacent connection portions 14 may be, for example, 20 μm or less, or 15 μm or less. Such connection portions 14 may be so-called microbumps.

[0032] Next, as shown in FIGS. 1B and 1C, once the semiconductor member 10 is prepared, a film adhesive 20 is prepared. The film adhesive 20 is, for example, an insulating adhesive such as NCF (Non-Conductive Film), and contains, for example, an epoxy resin, a curing agent, and a fluxing agent. A detailed configuration example of the film adhesive 20 will be described later. The film adhesive 20 is then attached to the semiconductor substrate 11 so as to cover the multiple connection terminals 12 and multiple bumps 13 of the semiconductor member 10, thereby obtaining a bonded body 30. In this attachment, for example, the semiconductor member 10 and the film adhesive 20 are heated to 60 to 100°C and pressurized for 30 seconds to 10 minutes, thereby laminating the film adhesive 20 to the semiconductor member 10. The film adhesive 20 can be attached to the main surface 11a of the semiconductor substrate 11 by, for example, heat pressing, roll lamination, or vacuum lamination.

[0033] The film-like adhesive 20 is configured to be thicker than the height of the connection portion 14 at least after being attached (laminated) to the semiconductor substrate 11 (in the state of the bonded body 30). The film-like adhesive 20 may have a thickness of 1.2 times or more, 1.5 times or more, or even 2 times or more the height of the connection portion 14 after being attached to the semiconductor substrate 11. Furthermore, the film-like adhesive 20 may have a thickness of 15 μm or more, or 7 μm or more after being attached to the semiconductor substrate 11. The film-like adhesive 20 may be thicker than the height of the connection portion 14 at the stage before being laminated to the semiconductor substrate 11 (i.e., at the stage when the film-like adhesive 20 is prepared). The film-like adhesive 20 may be thinner than the height of the connection portion 14 at the stage before lamination. The thickness of the film-like adhesive 20 after application may change (lift up) depending on the number (installation density) and size of the connection portions 14 (e.g., bumps) provided on the semiconductor substrate 11, and even if the thickness of the film-like adhesive is thin before application, it is possible to make the film-like adhesive 20 thicker than the height of the connection portions 14 after application.

[0034] The film adhesive 20 may have a protective film 21 on a surface 20b opposite to the surface 20a attached to the semiconductor substrate 11. The protective film 21 is, for example, a backgrinding tape (BG tape). The backgrinding tape is, for example, a tape used to protect the circuit surface from scratches and contamination during backgrinding of a semiconductor wafer. When the protective film 21 is provided, the back surface 11b opposite to the main surface 11a of the semiconductor substrate 11 may be ground while the film adhesive 20 with the protective film 21 covers the multiple connection portions 14. This allows the semiconductor substrate 11 to be reduced to a desired thickness. As shown in FIG. 2A , the protective film 21 is peeled off from the film adhesive 20 after the back surface 11b of the semiconductor substrate 11 is ground. In this embodiment, the film adhesive 20 has a sufficient thickness at this stage, preventing peeling in response to the peeling of the protective film 21.

[0035] Next, after the protective film 21 is peeled off from the film adhesive 20 and before the film adhesive 20 is ground, the film adhesive 20 may be subjected to a curing process. This curing does not completely cure the film adhesive 20, but rather lightly cures it. For example, the film adhesive 20 may be cured so that the degree of cure is about 10%. The curing here may be thermal curing or light (ultraviolet) curing.

[0036] Next, as shown in FIGS. 2B and 2C , the film adhesive 20 of the bonded body 35 from which the protective film 21 has been peeled is ground. The film adhesive 20 is ground to a predetermined thickness using at least one of a grinder, a surface planer, and a CMP (chemical vapor mechanical polishing) device as the device C for grinding the film adhesive 20. A CMP device is preferably used as the method for grinding the film adhesive 20. This results in a smooth ground surface. In the grinding process of the film adhesive 20, the film adhesive 20 is ground so that the surface 13 a of the bump 13 and the surface 20 c of the film adhesive 20A are flush with each other. Note that the term "flush" here refers not only to the case where the surface 13 a of the bump 13 and the surface 20 c of the film adhesive 20A are completely flush with each other, but also to the case where a thin layer of adhesive remains on the surface 13 a of the solder bump 13.

[0037] 2C, the film adhesive 20 is ground to be thinner, and the bonded body 35 after the film adhesive 20A is ground is then singulated into a plurality of semiconductor chips (not shown). This makes it possible to easily obtain semiconductor chips provided with minute bumps (microbumps, etc.).

[0038] 3A and 3B, at least one semiconductor chip 40 of the plurality of semiconductor chips is placed on a wiring substrate 45 (substrate), and the semiconductor chip 40 is mounted on the wiring substrate 45 by heating and pressurizing. As a result, the bumps 13 of the semiconductor chip 40 are connected to the connection terminals 46 of the wiring substrate 45, and the semiconductor substrate 11 and the wiring substrate 45 are fixed to each other by the film adhesive 20A, thereby producing a semiconductor device 50. Note that if the semiconductor chip 40 has a TSV (Through-Silicon Via) structure, a plurality of semiconductor chips 40 may be stacked three-dimensionally, and then the stacked plurality of semiconductor chips 40 may be collectively heated and pressurized to form a multi-tiered semiconductor device.

[0039] Here, the effects of the semiconductor device manufacturing method according to this embodiment will be explained in comparison with the manufacturing method of a comparative example shown in FIG. 4 . As shown in FIG. 4A, in manufacturing the semiconductor device according to the comparative example, a film-like adhesive 120 is prepared having a thickness roughly equal to the height of the connection portions 14 consisting of the connection terminals 12 and bumps 13 on the semiconductor member 10. Then, as shown in FIG. 4B, the film-like adhesive 120 having such a thickness is attached to the semiconductor substrate 11 so as to cover the connection portions 14. Because the film-like adhesive 120 is thin (e.g., 10 μm or less or 7 μm or less), thickness variations in the film-like adhesive 120 are likely to occur. Furthermore, voids are likely to remain when the film-like adhesive 120 is laminated to the semiconductor substrate 11 (e.g., a semiconductor wafer), resulting in a decrease in the manufacturing yield of the semiconductor device. Furthermore, because the connection portions 14, which are bumps, are minute, the connection portions 14 may be deformed when the thin film-like adhesive 120 is laminated, potentially causing problems during mounting.

[0040] Next, as shown in Fig. 4(b), the film adhesive 120 is attached to the semiconductor substrate 11, and the rear surface 11b of the rear side of the semiconductor substrate 11 is ground. Then, when grinding is completed, as shown in Fig. 4(c), the BG tape, which is the protective film 21, is peeled off from the film adhesive 120. When the BG tape is peeled off, because the film adhesive 120 is thin, part of the film adhesive 120 may peel off together.

[0041] In contrast, in the semiconductor device manufacturing method according to this embodiment, the film-like adhesive 20 thicker than the height of the connection portion 14 (the total height of the connection terminals 12 and the bumps 13) is ground in the process of preparing the bonded body 30. This allows a thicker film to be used for the film-like adhesive 20 before grinding, thereby suppressing thickness variations in the film-like adhesive 20 provided on the main surface 11a of the semiconductor substrate 11 and suppressing the formation of voids. Furthermore, deformation of the bumps when applying the film-like adhesive 20 can also be suppressed. In this manufacturing method, portions of the thick film-like adhesive 20 unnecessary for mounting are removed by the grinding process, thereby suppressing problems during mounting. Therefore, this semiconductor device manufacturing method can improve the manufacturing yield of semiconductor devices 50 even when the connection portion 14 is miniaturized.

[0042] In the method for manufacturing a semiconductor device according to this embodiment, a thick film adhesive is ground to make it thinner. As a result, although the film adhesive 20 is laminated on the semiconductor substrate 11 and is thick relative to the height of the connection portions 14 (bumps), it is later thinned by grinding, which increases the amount of resin on the connection portions 14 (solder bumps, etc.), preventing the resin from getting caught during mounting or the fillet from becoming larger than necessary.

[0043] In the method for manufacturing a semiconductor device according to this embodiment, a curing treatment can be performed on the film-like adhesive 20 of the bonded body 30 before grinding the film-like adhesive 20. Because the film-like adhesive 20 is viscous and may be soft, such a curing treatment can more reliably grind the film-like adhesive.

[0044] In the method for manufacturing a semiconductor device according to this embodiment, when preparing the bonded body 30, the back surface 11b of the semiconductor substrate 11 opposite the main surface 11a is ground while the film adhesive 20 provided with the protective film 25 covers the connecting portions 14, and the protective film 25 is peeled off after grinding the semiconductor substrate 11 but before grinding the film adhesive 20. By using a thicker film adhesive 20 and protective film 21 during bonding in this manner, the semiconductor substrate 11 can be thinned to a predetermined thickness without deforming or damaging the connecting portions 14, which are microbumps. Furthermore, when peeling the protective film 25 from the film adhesive 20, it is possible to prevent a portion of the film adhesive 20 from peeling off along with the protective film 25.

[0045] [Film-like adhesive] The film-like adhesive used in this embodiment will be described below. However, the film-like adhesive 20 is not limited to the following and may have other configurations. As an example, the film-like adhesive 20 is a member containing an epoxy resin, a curing agent, and a fluxing agent.

[0046] The epoxy resin contained in the film adhesive is selected from, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, naphthalene type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, phenol aralkyl type epoxy resin, biphenyl type epoxy resin, triphenylmethane type epoxy resin, dicyclopentadiene type epoxy resin, and various polyfunctional epoxy resins. These can be used alone or in combination of two or more. The weight average molecular weight of the epoxy resin is usually less than 10,000.

[0047] The content of the epoxy resin may be, for example, 5 to 75 mass %, 10 to 50 mass %, or 15 to 35 mass %, based on the total mass of the film adhesive.

[0048] The curing agent contained in the film-like adhesive includes, for example, at least one selected from imidazole-based curing agents, phenolic resin-based curing agents, acid anhydride-based curing agents, amine-based curing agents, and phosphine-based curing agents. The imidazole-based curing agents, phenolic resin-based curing agents, acid anhydride-based curing agents, and amine-based curing agents exhibit flux activity that suppresses the formation of an oxide film on the connection portion 14, and can contribute to improving connection reliability and insulation reliability.

[0049] Examples of the imidazole curing agent include 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyano-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine ... 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and an adduct of an epoxy resin and an imidazole compound. When the imidazole-based curing agent is 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid, 2-phenyl-4,5-dihydroxymethylimidazole, or a combination thereof, the increase in melt viscosity of the film-like adhesive due to heat treatment is easily suppressed appropriately. The imidazole-based curing agent may be a microencapsulated latent curing agent.

[0050] When the content of the imidazole-based curing agent is low, the increase in the melt viscosity of the film-like adhesive due to heat treatment is easily suppressed appropriately. Therefore, for example, the content of the imidazole-based curing agent may be 5 parts by mass or less, 4 parts by mass or less, or 1 part by mass or more per 100 parts by mass of the epoxy resin content. The imidazole-based curing agent may be combined with a phenolic resin-based curing agent, an acid anhydride-based curing agent, or an amine-based curing agent.

[0051] The phenolic resin curing agent is a compound having two or more phenolic hydroxyl groups, and examples thereof include phenol novolac resin, cresol novolac resin, phenol aralkyl resin, cresol naphthol formaldehyde polycondensate, triphenylmethane-type polyfunctional phenolic resin, and various polyfunctional phenolic resins. These can be used alone or in combination of two or more.

[0052] The equivalent ratio of the phenolic resin-based curing agent to the epoxy resin (phenolic hydroxyl group / epoxy group, molar ratio) may be 0.3 to 1.5, 0.4 to 1.0, or 0.5 to 1.0, from the viewpoint of good curability, adhesion, and storage stability. When the equivalent ratio is 0.3 or more, curability and adhesive strength tend to be improved. When the equivalent ratio is 1.5 or less, no excessive unreacted phenolic hydroxyl groups remain, the water absorption rate is kept low, and insulation reliability tends to be improved.

[0053] Examples of acid anhydride curing agents include methylcyclohexanetetracarboxylic dianhydride, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic dianhydride, and ethylene glycol bisanhydrotrimellitate, which can be used alone or in combination of two or more.

[0054] The equivalent ratio of the acid anhydride curing agent to the epoxy resin (acid anhydride group / epoxy group, molar ratio) may be 0.3 to 1.5, 0.4 to 1.0, or 0.5 to 1.0, from the viewpoint of good curability, adhesion, and storage stability. When the equivalent ratio is 0.3 or more, the curability and adhesive strength tend to be improved. When the equivalent ratio is 1.5 or less, no excess unreacted acid anhydride remains, the water absorption rate is kept low, and insulation reliability tends to be improved.

[0055] As the amine-based curing agent, for example, dicyandiamide can be used.

[0056] The equivalent ratio of the amine curing agent to the epoxy resin (amine / epoxy group, molar ratio) may be 0.3 to 1.5, 0.4 to 1.0, or 0.5 to 1.0, from the viewpoint of good curability, adhesion, and storage stability. When the equivalent ratio is 0.3 or more, curability and adhesive strength tend to be improved. When the equivalent ratio is 1.5 or less, no excessive unreacted amine remains, and insulation reliability tends to be improved.

[0057] Examples of phosphine-based curing agents include triphenylphosphine, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra(4-methylphenyl)borate, and tetraphenylphosphonium(4-fluorophenyl)borate.

[0058] The content of the phosphine-based curing agent may be 0.1 to 10 parts by mass, or 0.1 to 5 parts by mass, relative to 100 parts by mass of the epoxy resin. When the content of the phosphine-based curing agent is 0.1 parts by mass or more, curability tends to be improved. When the content of the phosphine-based curing agent is 10 parts by mass or less, the adhesive tends to be difficult to cure before a metal bond is formed, and connection failures tend to be less likely to occur. The phosphine-based curing agent may be combined with a phenolic resin-based curing agent, an acid anhydride-based curing agent, or an amine-based curing agent.

[0059] The fluxing agent contained in the film-like adhesive can be, for example, a single compound having a group represented by formula (1), or a combination of two or more compounds.

[0060]

[0061] In formula (1), R １ represents an electron-donating group. Examples of the electron-donating group include an alkyl group, a hydroxyl group, an amino group, an alkoxy group, and an alkylamino group. The electron-donating group may be an alkyl group, a hydroxyl group, or an alkoxyl group, or may be an alkyl group.

[0062] The alkyl group may be an alkyl group having 1 to 10 carbon atoms or an alkyl group having 1 to 5 carbon atoms. The alkyl group may be linear or branched, or may be linear. When the alkyl group is linear, from the viewpoint of steric hindrance, the number of carbon atoms in the alkyl group may be equal to or less than the number of carbon atoms in the main chain containing the carboxylic acid.

[0063] The alkoxy group may be an alkoxy group having 1 to 10 carbon atoms or an alkoxy group having 1 to 5 carbon atoms. The alkyl group portion of the alkoxy group may be linear or branched, or may be linear. When the alkyl group portion of the alkoxy group is linear, the number of carbon atoms may be equal to or less than the number of carbon atoms in the main chain containing the carboxylic acid, from the viewpoint of steric hindrance.

[0064] The alkylamino group may be a monoalkylamino group or a dialkylamino group. The monoalkylamino group may be a monoalkylamino group having 1 to 10 carbon atoms or a monoalkylamino group having 1 to 5 carbon atoms. The alkyl group portion of the monoalkylamino group may be linear or branched, or may be linear. The dialkylamino group may be a dialkylamino group having 1 to 20 carbon atoms or a dialkylamino group having 1 to 10 carbon atoms. The alkyl group portion of the dialkylamino group may be linear or branched, or may be linear.

[0065] The fluxing agent may be a dicarboxylic acid compound having two carboxyl groups. Compared to monocarboxylic acids having one carboxyl group, dicarboxylic acid compounds are less likely to volatilize even at high temperatures during connection, and can further suppress the occurrence of voids. Use of a dicarboxylic acid compound can further suppress the increase in viscosity of the adhesive during storage, connection work, etc., compared to when a compound having three or more carboxyl groups is used. As a result, the connection reliability of the semiconductor device can be further improved.

[0066] The fluxing agent may contain a dicarboxylic acid compound represented by the following formula (2): A fluxing agent containing the dicarboxylic acid compound represented by the following formula (2) can further improve the reflow resistance and connection reliability of a semiconductor device.

[0067]

[0068] In formula (2), R １ represents an electron-donating group, R ２ represents a hydrogen atom or an electron-donating group, and n represents an integer of 0 to 10.

[0069] In formula (2), n may be an integer of 2 to 10, or an integer of 0 to 8. When n is 10 or less, flux activity is exhibited in a shorter time, and even better connection reliability can be obtained, particularly when the connection time is short. When n is 2 or more, volatilization is less likely even at high temperatures during connection, and the generation of voids can be further suppressed.

[0070] R ２ may be a hydrogen atom or an electron-donating group. ２ When R is a hydrogen atom, the melting point tends to be low, and the connection reliability (solder wettability) may be improved. １ and R ２ The melting point of the fluxing agent where R is a methyl group is １ or R ２ The melting point of the fluxing agent tends to be higher than that of a fluxing agent in which one of the groups is a methyl group.

[0071] The melting point of the fluxing agent may be 150°C or lower, 140°C or lower, or 130°C or lower. If the melting point of the fluxing agent is low, the fluxing activity is likely to be fully expressed before the curing reaction between the epoxy resin and the curing agent occurs, thereby making it possible to obtain a semiconductor device with even better connection reliability. The melting point of the fluxing agent may be 25°C or higher, or 50°C or higher. The melting point of the fluxing compound can be measured, for example, by attaching a capillary tube filled with a sample to a double-tube thermometer and heating it in a hot bath.

[0072] The fluxing agent may contain, for example, at least one compound selected from the group consisting of succinic acid, 2-methylglutaric acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid.

[0073] The content of the fluxing agent may be 0.5 to 10 mass %, or 0.5 to 5 mass %, based on the total mass of the film adhesive.

[0074] The film adhesive may further contain a polymer component as needed. A film adhesive containing a polymer component has even better heat resistance and film-forming properties.

[0075] Examples of polymer components include phenoxy resin, polyimide resin, polyamide resin, polycarbodiimide resin, cyanate ester resin, acrylic resin, polyester resin, polyethylene resin, polyethersulfone resin, polyetherimide resin, polyvinyl acetal resin, urethane resin, and acrylic rubber. Among these, from the viewpoint of excellent heat resistance and film formability, the high molecular weight component may be phenoxy resin, polyimide resin, acrylic rubber, cyanate ester resin, or polycarbodiimide resin, or may be phenoxy resin, polyimide resin, or acrylic rubber. These polymer components may be used alone or in combination of two or more. In this specification, the polymer component does not include the above-mentioned epoxy resin.

[0076] The glass transition temperature (Tg) of the polymer component may be 200°C or less, 180°C or less, or 150°C or less, or may be 50°C or more, from the viewpoint of the adhesiveness of the film-like adhesive to the semiconductor substrate. If the Tg of the polymer component exceeds 200°C, it becomes difficult for the adhesive to fill in the irregularities of the bumps of the semiconductor chip, the electrodes and wiring patterns formed on the substrate, etc., and the void suppression effect may be relatively reduced. The Tg here is the Tg measured using a DSC (PerkinElmer DSC-7 model) under the conditions of a sample weight of 10 mg, a heating rate of 10°C / min, and a measurement atmosphere of air.

[0077] The weight average molecular weight of the polymer component is usually 10,000 or more. In order to exhibit good film-forming properties by itself, the weight average molecular weight of the polymer component may be 30,000 or more, 40,000 or more, or 50,000 or more. In this specification, the weight average molecular weight means a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0078] When the film adhesive contains a polymer component, the content C of the polymer component ｄ Epoxy resin content C ａ Ratio C ａ / C ｄ (mass ratio) may be 0.01 to 5, or 0.05 to 3, or 0.1 to 2. ａ / C ｄ When the ratio C is 0.01 or more, better curability and adhesive strength can be obtained. ａ / C ｄ When the value is 5 or less, better film formability is obtained.

[0079] The film adhesive may contain a filler as needed, which can, for example, further suppress the generation of voids during connection and reduce the moisture absorption rate of the cured adhesive.

[0080] The filler may be, for example, an insulating inorganic filler, whiskers, a resin filler, or a combination thereof. Examples of insulating inorganic fillers include glass, silica, alumina, titanium oxide, carbon black, mica, and boron nitride. The insulating inorganic filler may be at least one selected from silica, alumina, titanium oxide, and boron nitride, or at least one selected from silica, alumina, and boron nitride. Examples of whiskers include aluminum borate, aluminum titanate, zinc oxide, calcium silicate, magnesium sulfate, and boron nitride. Examples of resin fillers include fillers made of resins such as polyurethane and polyimide.

[0081] The shape, particle size and content of the filler are not particularly limited. The filler may have its physical properties appropriately adjusted by surface treatment.

[0082] The content of the filler may be 10 to 80% by mass, or 15 to 60% by mass, based on the total mass of the film adhesive.

[0083] In addition to the components exemplified above, the film adhesive may contain additives such as an antioxidant, a silane coupling agent, a titanium coupling agent, a leveling agent, an ion trapping agent, etc. These may be used alone or in combination of two or more.

[0084] The film-like adhesive can be obtained, for example, by a method including applying a resin varnish containing an epoxy resin, a curing agent, a fluxing agent, and other components added as needed, as well as an organic solvent, to a base film that has been subjected to a release treatment, and then removing the organic solvent from the coating by heating, thereby forming a film-like adhesive on the base film.

[0085] Examples of organic solvents used in preparing the resin varnish include dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, diethylene glycol dimethyl ether, toluene, benzene, xylene, methyl ethyl ketone, tetrahydrofuran, ethyl cellosolve, ethyl cellosolve acetate, butyl cellosolve, dioxane, cyclohexanone, and ethyl acetate. These organic solvents can be used alone or in combination of two or more. The stirring, mixing, and kneading during the preparation of the resin varnish can be performed using, for example, a mixer, a kneading machine, a three-roll mill, a ball mill, a bead mill, or a homodisper.

[0086] The substrate film is not particularly limited as long as it has heat resistance sufficient to withstand the heating conditions when volatilizing the organic solvent, and may be, for example, a polyolefin film such as a polypropylene film or a polymethylpentene film, a polyester film such as a polyethylene terephthalate film or a polyethylene naphthalate film, a polyimide film, or a polyetherimide film. The substrate film may be a single layer made of these films, or a multilayer film made of two or more types of films.

[0087] Drying conditions for volatilizing the organic solvent from the resin varnish coating can be, for example, heating for 0.1 to 90 minutes at a temperature of 50 to 200° C. The organic solvent may be removed to 1.5 mass % or less based on the total mass of the film-like adhesive.

[0088] 10...semiconductor member, 11...semiconductor substrate, 11a...main surface, 11b...rear surface, 12...connection terminal (first connection portion), 13...bump (second connection portion), 13a, 20c...surface, 14...connection portion, 20, 20A...film-like adhesive, 21...protective film, 30, 35...bonded body, 40...semiconductor chip, 45...wiring board (substrate), 50...semiconductor device.

Claims

1. A method for manufacturing a semiconductor device, comprising the steps of: preparing a bonded body having a semiconductor substrate, a connection portion provided on a main surface of the semiconductor substrate, and a film-like adhesive provided on the main surface of the semiconductor substrate so as to cover the connection portion; and grinding the film-like adhesive of the bonded body, wherein the film-like adhesive is thicker than the height of the connection portion in the preparation step.

2. The method of manufacturing a semiconductor device according to claim 1, wherein the film-like adhesive has a thickness that is 1.2 times or more the height of the connection portion in the preparing step.

3. The method of manufacturing a semiconductor device according to claim 1, wherein the film-like adhesive has a thickness that is 1.5 times or more the height of the connection portion in the preparing step.

4. A method for manufacturing a semiconductor device as claimed in any one of claims 1 to 3, wherein the connection portion includes a connection terminal provided on the main surface of the semiconductor substrate and a bump provided on the connection terminal, and in the grinding step, the film-like adhesive is ground so that a surface of the bump and a surface of the film-like adhesive are flush with each other.

5. A method for manufacturing a semiconductor device according to any one of claims 1 to 4, wherein in the preparing step, the film-like adhesive has a thickness of 15 μm or more, and in the grinding step, the film-like adhesive is ground so that the thickness of the film-like adhesive is 7 μm or less.

6. The method for manufacturing a semiconductor device according to claim 1, further comprising the step of performing a hardening process on the film-like adhesive of the bonded body before the grinding step.

7. A method for manufacturing a semiconductor device according to any one of claims 1 to 6, wherein the step of preparing the bonded body includes the steps of: preparing a semiconductor member having the semiconductor substrate and the connection portion; and attaching the film-like adhesive to the semiconductor substrate so as to cover the connection portion of the semiconductor member; and the film-like adhesive is thicker than the height of the connection portion after being attached to the semiconductor substrate.

8. A method for manufacturing a semiconductor device as described in claim 7, wherein the film-like adhesive has a protective film provided on a surface opposite to the surface attached to the semiconductor substrate, and the step of preparing the bonded body includes the steps of: grinding the back surface opposite to the main surface of the semiconductor substrate with the film-like adhesive with the protective film provided thereon covering the connection portion; and peeling off the protective film after the step of grinding the semiconductor substrate and before the step of grinding the film-like adhesive.

9. The method for manufacturing a semiconductor device according to any one of claims 1 to 8, wherein in the step of grinding the film-like adhesive, the film-like adhesive is ground using at least one of a grinder, a surface planer, and a CMP device.

10. The method for manufacturing a semiconductor device according to any one of claims 1 to 9, wherein the film-like adhesive contains an epoxy resin, a hardener, and a flux agent.

11. A method for manufacturing a semiconductor device according to any one of claims 1 to 10, further comprising the steps of: dividing the bonded body into a plurality of semiconductor chips after grinding off the film-like adhesive; and mounting at least one of the plurality of semiconductor chips on a substrate.

12. A film-like adhesive used in a manufacturing method for a semiconductor device, the method comprising the steps of: preparing a bonded body having a semiconductor substrate, a connection portion provided on a main surface of the semiconductor substrate, and a film-like adhesive provided on the main surface of the semiconductor substrate so as to cover the connection portion; and grinding the film-like adhesive of the bonded body, the film-like adhesive being configured in the preparation step to be thicker than the height of the connection portion.

13. The film-like adhesive according to claim 12, wherein the film-like adhesive has a thickness that is 1.2 times or more the height of the connection portion in the preparing step.

14. The film-like adhesive according to claim 12, wherein the film-like adhesive has a thickness that is 1.5 times or more the height of the connection portion in the preparing step.

15. The film-like adhesive according to any one of claims 12 to 14, comprising an epoxy resin, a curing agent, and a fluxing agent.

Images