Adhesive film, semiconductor device, and method for manufacturing semiconductor device

Abstract

This invention makes it possible to achieve a semiconductor device demonstrating excellent electrical connection reliability despite a narrow pitch between electrodes. There is provided an adhesive film which is used for bonding a semiconductor element with a semiconductor element or bonding a semiconductor element with a circuit board, the film having: a width of 40°C or more and less than 110°C of a temperature range indicative of a melt viscosity of 50000 Pa･s or less in a temperature range of more than 90°C and less than 200°C; and a ratio (V2 / V1) exceeding 1.0 of a melt viscosity V2 at 200°C to a minimum melt viscosity V1 in a temperature range of more than 90°C and less than 200°C.

Description

Adhesive film, semiconductor device, and method for manufacturing semiconductor device

[0001] The present invention relates to an adhesive film, a semiconductor device, and a method for manufacturing a semiconductor device.

[0002] In the manufacturing process of a semiconductor device, a mounting method using an adhesive film is known as a mounting method for joining a pair of electronic elements (a semiconductor element and a circuit board, or two semiconductor elements). In this mounting method, one electronic element is electrically connected to the other electronic element by applying heat and pressure with the adhesive film interposed between the pair of electronic elements (see, for example, Patent Documents 1 and 2).

[0003] JP 2021-119245 A JP 2017-145289 A

[0004] On the other hand, in recent years, in order to process and transfer larger amounts of data quickly and efficiently, there has been a demand for increasing the number of interconnections between semiconductor elements constituting a semiconductor device or between a semiconductor element and a circuit board, and shortening the wiring distance. To achieve this, it is necessary to narrow the pitch between electrodes such as bumps arranged on the surface of the semiconductor element or circuit board, and also to ensure the reliability of the electrical connection between the electrodes.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide an adhesive film that can produce a semiconductor device with excellent electrical connection reliability even when the pitch between electrodes is narrow, a semiconductor device manufactured using the same, and a method for manufacturing the semiconductor device.

[0006] The above object is achieved by the present invention as follows: The adhesive film of the present invention is used for bonding semiconductor elements to each other or for bonding semiconductor elements to a circuit board, and has a temperature range of 40°C or more and less than 110°C in which the adhesive film exhibits a melt viscosity of 50,000 Pa s or less in the temperature range of more than 90°C and less than 200°C, and the ratio (V2 / V1) of the melt viscosity V2 at 200°C to the minimum melt viscosity V1 in the temperature range of more than 90°C and less than 200°C exceeds 1.0.

[0007] In one embodiment of the adhesive film of the present invention, the melt viscosity V2 is preferably 8000 Pa·s or more.

[0008] In another embodiment of the adhesive film of the present invention, the film thickness is preferably 0.5 μm to 6 μm.

[0009] In another embodiment of the adhesive film of the present invention, the film thickness is preferably 0.5 μm to 2.5 μm.

[0010] In another embodiment of the adhesive film of the present invention, the circuit board is preferably a substrate in which a circuit is formed on a silicon substrate or a substrate in which a circuit is formed on a glass substrate.

[0011] In another embodiment of the adhesive film of the present invention, it is preferable that the material constituting the surface of the electrode provided on the semiconductor element is made of a metal material containing at least one element selected from the group consisting of Au and Sn as its main component.

[0012] In another embodiment of the adhesive film of the present invention, the maximum diameter of the electrodes provided on the semiconductor element is preferably 0.5 μm to 5 μm.

[0013] In another embodiment of the adhesive film of the present invention, the electrodes provided on the semiconductor element preferably have an inter-electrode pitch of 0.5 μm to 5 μm.

[0014] In another embodiment of the adhesive film of the present invention, it is preferable that the material constituting the surface of the electrode provided on the circuit board is made of a metal material containing at least one element selected from the group consisting of Au and Sn as its main component.

[0015] In another embodiment of the adhesive film of the present invention, the maximum diameter of the electrodes provided on the circuit board is preferably 0.5 μm to 5 μm.

[0016] In another embodiment of the adhesive film of the present invention, the electrodes provided on the circuit board preferably have an inter-electrode pitch of 0.5 μm to 5 μm.

[0017] Another embodiment of the adhesive film of the present invention preferably contains a thermosetting resin and a thermoplastic resin.

[0018] In another embodiment of the adhesive film of the present invention, the thermosetting resin preferably contains a polyphenylene ether resin as a main component.

[0019] In another embodiment of the adhesive film of the present invention, the thermoplastic resin preferably contains a styrene-based elastomer as a main component.

[0020] Another embodiment of the adhesive film of the present invention preferably does not contain a filler.

[0021] The first semiconductor device of the present invention comprises a first semiconductor element having an electrode, a second semiconductor element having an electrode directly connected to an electrode of the first semiconductor element, and a cured product of the adhesive film of the present invention disposed between the first semiconductor element and the second semiconductor element.

[0022] A first method for manufacturing a semiconductor device of the present invention includes the steps of: attaching an adhesive film of the present invention to an electrode placement surface on which the electrodes of a first semiconductor element are arranged; and contacting the surface of the adhesive film opposite the side on which the first semiconductor element is arranged with the electrode placement surface on which the electrodes of the second semiconductor element are arranged, so that the electrodes of the first semiconductor element and the electrodes of the second semiconductor element face each other, thereby heating and pressurizing a laminate in which the first semiconductor element, the adhesive film, and the second semiconductor element are stacked in this order.

[0023] The second semiconductor device of the present invention comprises a semiconductor element having an electrode, a circuit board having an electrode directly connected to an electrode of the semiconductor element, and a cured product of the adhesive film of the present invention disposed between the semiconductor element and the circuit board.

[0024] A second method for manufacturing a semiconductor device of the present invention includes the steps of: attaching the adhesive film of the present invention to the electrode placement surface on which the electrodes of a semiconductor element are arranged; and contacting the surface of the adhesive film opposite the side on which the semiconductor element is arranged with the electrode placement surface on which the electrodes of the circuit board are arranged so that the electrodes of the semiconductor element and the electrodes of the circuit board face each other, thereby heating and pressurizing a laminate in which the semiconductor element, the adhesive film, and the circuit board are stacked in this order.

[0025] A third method for manufacturing a semiconductor device of the present invention includes the steps of: attaching an adhesive film of the present invention to the electrode placement surface of a circuit board on which the electrodes are arranged; and contacting the surface of the adhesive film opposite the side on which the circuit board is arranged with the electrode placement surface on which the electrodes of the semiconductor element are arranged, so that the electrodes of the circuit board face each other, thereby heating and pressurizing a laminate in which the semiconductor element, the adhesive film, and the circuit board are stacked in this order.

[0026] According to the present invention, it is possible to provide an adhesive film that can obtain a semiconductor device with excellent electrical connection reliability even when the pitch between electrodes is narrow, a semiconductor device manufactured using the same, and a method for manufacturing the semiconductor device.

[0027] The adhesive film of this embodiment is used in the manufacturing process of a semiconductor device to bond semiconductor elements to one another or to bond semiconductor elements to a circuit board. The adhesive film of this embodiment has a temperature range of 40°C or higher and lower than 110°C, at which it exhibits a melt viscosity of 50,000 Pa·s or less in the temperature range of greater than 90°C and less than 200°C, and the ratio (V2 / V1) of the melt viscosity V2 at 200°C to the minimum melt viscosity V1 in the temperature range of greater than 90°C and less than 200°C exceeds 1.0. Therefore, by using the adhesive film of this embodiment, a semiconductor device with excellent electrical connection reliability can be obtained, even if the pitch between electrodes is narrow. The reasons for this effect are as follows.

[0028] First, the surfaces of electrodes provided on semiconductor elements or circuit boards are generally made of Au or Sn, or alloy materials containing these metal elements as the main component. Therefore, when electrically joining electronic elements, in other words, when joining electrodes, the joining is performed by utilizing the interdiffusion of the metal elements that make up the electrode surfaces. Furthermore, such joining by utilizing the interdiffusion of metal elements requires a heat treatment at approximately 240°C to 250°C.

[0029] Here, (i) in the process of joining a pair of electronic elements (semiconductor elements and semiconductor elements, or semiconductor elements and circuit boards) (i.e., in the process of heating from near room temperature to a temperature range (approximately 240°C to 250°C) where bonding of electrodes occurs due to mutual diffusion of metal elements), the adhesive film must be heated to a paste or liquid state with sufficient fluidity from a solid state, so that it can be quickly extruded from between the pair of electrodes to be connected. This is because, when bonding of the pair of electronic elements is completed, it is possible to prevent the cured adhesive film from remaining between the pair of electrodes, thereby ensuring electrical connection reliability. (ii) Furthermore, in the temperature range (approximately 240°C to 250°C) where bonding of electrodes occurs due to mutual diffusion of metal elements, the adhesive film must be completely cured by the curing reaction (i.e., the adhesive film must be thermally cured and return to a solid state (cured product)). In other words, it can be said that the curing reaction of the adhesive film must be initiated at a temperature range somewhat lower than the temperature range of approximately 240°C to 250°C.

[0030] On the other hand, narrowing the inter-electrode pitch requires reducing the size of the electrodes, specifically the maximum diameter of the electrodes, which here refers to the maximum length of the electrodes in a direction parallel to the surface of the semiconductor element or circuit board on which the electrodes are arranged (electrode arrangement surface).

[0031] Furthermore, when the size of the electrodes is reduced, the contact surface between the pair of electrodes connected to each other becomes smaller when joining a pair of electronic elements (semiconductor elements and semiconductor elements, or semiconductor elements and circuit boards).For this reason, (iii) even when the pitch between the electrodes is narrowed, in order to more reliably connect the electrodes via the narrow contact surface, it is more necessary to more reliably remove the adhesive film from between the pair of electrodes when joining the pair of electronic elements.

[0032] Taking into account the properties required of an adhesive film as explained above in (i) to (iii), the adhesive film of this embodiment has a temperature range in which it exhibits a melt viscosity of 50,000 Pa s or less in the temperature range of more than 90°C and less than 200°C of 40°C or more and less than 110°C, and the ratio (V2 / V1) of the melt viscosity V2 at 200°C to the minimum melt viscosity V1 in the temperature range of more than 90°C and less than 200°C exceeds 1.0.

[0033] First, when the width of the temperature range showing a melt viscosity of 50,000 Pa·s or less is set to 40°C or more in the temperature range above 90°C and below 200°C, it is believed that the effects described below in (a) and (b) are achieved. That is, (a) With a melt viscosity of 50,000 Pa·s or less, the adhesive film becomes paste-like or liquefied and has sufficient fluidity. Therefore, in the process of heating and pressurizing a pair of electronic elements with the adhesive film interposed therebetween, it becomes possible to extrude and remove the adhesive film from between the pair of electrodes that are connected to each other. (b) Furthermore, when the width of the temperature range showing a melt viscosity of 50,000 Pa·s or less is 40°C or more, sufficient time can be ensured to completely extrude and remove the adhesive film from between the pair of electrodes. As a result, when the pitch between the electrodes is narrowed, it becomes extremely easy to ensure connection between the electrodes via a narrow contact surface.

[0034] In order to more effectively achieve the effect described in (b) above, the temperature range is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 70°C or higher, and the wider the temperature range, the better. However, if the temperature range is too wide, the heat resistance of the adhesive film may be easily deteriorated when exposed to a high-temperature environment during storage or transportation, or the temperature at which the curing reaction begins (meaning an increase in melt viscosity) may shift to a higher temperature, which may prevent the adhesive film from curing sufficiently even in the temperature range (around 240°C to 250°C) where bonding between electrodes occurs due to interdiffusion of metal elements. From this practical standpoint, the temperature range must be set to less than 110°C, preferably 100°C or lower, and more preferably 90°C or lower.

[0035] Furthermore, a ratio (V2 / V1) of the melt viscosity V2 at 200°C to the minimum melt viscosity V1 in the temperature range greater than 90°C and less than 200°C of greater than 1.0 means that, during heating of the adhesive film, the melt viscosity tends to increase at 200°C, which is higher than the temperature range (greater than 90°C and less than 200°C) exhibiting the minimum melt viscosity V1. In other words, this means that the curing reaction of the adhesive film has begun and is progressing. Therefore, by the time the temperature range (approximately 240°C to 250°C) where electrodes bond due to mutual diffusion of metal elements is reached, the adhesive film is considered to have sufficiently progressed in hardening due to the curing reaction. Therefore, in the temperature range where electrodes bond, the phenomenon that occurred in a temperature range lower than this temperature range (the state in which the fluidized adhesive film is extruded and removed from between the pair of electrodes) is stably maintained and fixed. From the same perspective, the melt viscosity V2 is preferably 8000 Pa·s or more, more preferably 10000 Pa·s or more, and even more preferably 20000 Pa·s or more.

[0036] From the viewpoint of sufficiently increasing the degree of curing of the adhesive film when it reaches the temperature range (around 240 ° C to 250 ° C) where bonding between electrodes occurs due to interdiffusion of metal elements, V2 / V1 is preferably 1.001 or more, more preferably 1.01 or more, and even more preferably 1.02 or more. From the viewpoint described above, the larger V2 / V1 is, the better. However, if it is too large, the curing reaction (which increases the melt viscosity) tends to start at temperatures significantly below 200 ° C., making it difficult to set the temperature range showing a melt viscosity of 50,000 Pa s or less to 40 ° C or more in the temperature range from above 90 ° C to below 200 ° C. Therefore, the upper limit of V2 / V1 is preferably 20 or less, more preferably 10 or less, and even more preferably 3 or less. From the same viewpoint, the melt viscosity V2 is preferably 100,000 Pa·s or less, more preferably 80,000 Pa·s or less, and even more preferably 60,000 Pa·s or less.

[0037] The adhesive film of this embodiment is in a solid state (non-fluidized state) at around room temperature (25°C), but from the viewpoint of handleability and quality retention taking into account temperature changes normally expected in storage and transportation environments, it is preferable that the adhesive film be in a solid state in a temperature range from around room temperature to 80°C, and more preferably in a solid state in a temperature range from around room temperature to 90°C.

[0038] On the other hand, when an adhesive film is used to electrically connect a pair of electronic elements (semiconductor element and semiconductor element, or semiconductor element and circuit board), a space (gap) is required between the pair of electronic elements to interpose the adhesive film. For this reason, at least one of the electrodes of the pair of electronic elements must be a convex electrode (bump) that protrudes from the surrounding surface of the electrode. In other words, the combination of the electrode of one electronic element and the electrode of the other electronic element to be electrically connected is selected from (i) a bump-bump combination, or (ii) a bump-pad combination (an electrode consisting of a flat surface that is flush with the surrounding surface of the electrode).

[0039] Furthermore, if the maximum diameter of the bumps is reduced to narrow the pitch between the electrodes, the bump height will inevitably have to be reduced to some extent, and the gap formed between the pair of electronic elements will inevitably have to be reduced. In addition, from the viewpoint of meeting the need to shorten the wiring distance of the wiring formed in the semiconductor device, the narrower the space (gap) through which the adhesive film is interposed between the pair of electronic elements, the better. Therefore, from the viewpoint of selecting the thickness of the adhesive film corresponding to the narrowed gap between the pair of electronic elements, the adhesive film of this embodiment preferably has a thickness of 0.5 μm to 6 μm, more preferably 0.5 μm to 4 μm, even more preferably 0.5 μm to 2.5 μm, and particularly preferably 0.5 μm to 1.5 μm. If the thickness of the adhesive film exceeds 6 μm, when a pair of electronic elements are joined using the adhesive film, the cured adhesive film is likely to remain between the electrodes of one electronic element and the electrodes of the other electronic element, which may result in a decrease in the electrical connection reliability of the semiconductor device.

[0040] On the other hand, considering the need to accommodate narrower inter-electrode pitches and shorter wiring distances, the thinner the adhesive film, the better; in that sense, there is no minimum thickness limit. However, extremely narrowing the inter-electrode pitch or shortening the wiring distance also means that the gap between a pair of electrically connected electronic elements becomes extremely narrow. In such cases, minute foreign particles such as dust and dirt present in the semiconductor device manufacturing environment (clean room) can easily enter the gap between the pair of electronic elements, resulting in a decrease in the electrical connection reliability of the semiconductor device. One solution to this problem is to increase the cleanliness of the clean room. However, it is difficult to completely remove minute foreign particles of a size that would reduce the electrical connection reliability of the semiconductor device, and the cost of ensuring and maintaining a high-clean environment is high, making the above-mentioned solution impractical. Therefore, even when narrowing the inter-electrode pitch or shortening the wiring distance, it is necessary to consider the balance with the manufacturing cost of the semiconductor device and prevent the gap between the pair of electronic elements from becoming extremely narrow. In consideration of such practical circumstances, it can be said that the lower limit of the thickness of the adhesive film of this embodiment is preferably 0.5 μm or more.

[0041] The adhesive film of this embodiment can be used for bonding semiconductor elements together, or for bonding semiconductor elements to a circuit board. However, from the viewpoints of being able to provide a larger number of electrical connection points within the semiconductor device, shortening the wiring distance, and even realizing a semiconductor device in which semiconductor elements are three-dimensionally integrated, it is particularly suitable to use the adhesive film of this embodiment for bonding semiconductor elements together.

[0042] The semiconductor elements used for bonding may be wafer-shaped semiconductor elements, or chip-shaped semiconductor elements obtained by dicing a wafer-shaped semiconductor element into individual pieces. When bonding semiconductor elements together, bonding of wafer-shaped semiconductor elements may be performed, or bonding of a chip-shaped semiconductor element to a wafer-shaped semiconductor element may be performed. When bonding a semiconductor element to a circuit board, either a wafer-shaped semiconductor element or a chip-shaped semiconductor element may be used as the semiconductor element.

[0043] Known circuit boards can be used as the circuit board. In addition to the commonly used glass epoxy circuit board (a circuit board formed on a glass epoxy substrate), other options include a silicon circuit board (a circuit board formed on a silicon substrate) and a glass circuit board (a circuit board formed on a glass substrate). However, glass epoxy circuit boards contain a large amount of easily deformable resin material, which can lead to significant warping and waviness. Therefore, narrowing the inter-electrode pitch when bonding a semiconductor element to a glass epoxy circuit board can lead to significant variations in the gap between the semiconductor element and the glass epoxy circuit board. In such cases, bonding a semiconductor element to a glass epoxy circuit board using an adhesive film of this embodiment with a thickness of 1 μm or less can easily degrade the reliability of the electrical connection. Considering these points, when using the adhesive film of this embodiment to bond a semiconductor element to a glass epoxy circuit board, the thickness of the adhesive film is preferably greater than 1 μm and less than 6 μm, more preferably 1.5 μm to 6 μm, and even more preferably 2 μm to 6 μm. On the other hand, silicon circuit boards and glass circuit boards, which are made solely of inorganic materials that are less likely to deform than resin materials, have significantly less warping and undulation than glass epoxy circuit boards, and therefore the variation in the gap formed between the semiconductor element and the silicon circuit board or glass circuit board is also very small. Therefore, when the adhesive film of this embodiment is used to bond these circuit boards and semiconductor elements, its thickness can be appropriately selected within the range of 0.5 μm to 6 μm. Taking these points into consideration, silicon circuit boards or glass circuit boards are suitable as circuit boards used to bond semiconductor elements and circuit boards.

[0044] Furthermore, the electrodes provided on the semiconductor element and circuit board used for bonding using the adhesive film of this embodiment have the specifications described below. First, the material constituting the surface of the electrode provided on the semiconductor element or circuit board (the portion that can serve as the connection surface for other electrodes) is made of a metal material containing at least one element selected from the group consisting of Au and Sn as the main component. Here, in this paragraph, "main component" means that the content of Au or Sn in the metal material is 50 atomic % or more, preferably 80 atomic % or more, and more preferably 90 atomic % or more. It is particularly preferable that the material constituting the surface of the electrode is composed only of Au or Sn. Note that the metal materials constituting the surface and the interior of the electrode may be different, but it is usually preferable that the material constituting the electrode surface and the material constituting the interior are the same.

[0045] Furthermore, from the viewpoint of facilitating narrowing of the inter-electrode pitch, the maximum diameter of the electrodes is preferably 0.5 μm to 5 μm, more preferably 0.5 μm to 2 μm. Furthermore, from the viewpoint of narrowing the inter-electrode pitch, the pitch between the electrodes is preferably 0.5 μm to 5 μm, more preferably 0.5 μm to 2.5 μm, and even more preferably 0.5 μm to 1.5 μm. Note that the pitch between the electrodes refers to the shortest distance between the center point of one electrode and the center point of the other electrode located closest to the first electrode, when the center point is the position that bisects the maximum diameter of the electrode. Furthermore, the planar shape of the electrodes is not particularly limited, and examples include polygonal, circular, and elliptical shapes. However, when the electrodes are bumps, a circular or polygonal shape (however, a polygonal shape whose planar shape is closer to a circle, such as a hexagonal or octagonal shape) is preferred. The cross-sectional shape of the bump (cross-sectional shape in a plane perpendicular to the electrode placement surface) is not particularly limited as long as it forms a convex shape, but is generally semicircular, approximately semicircular, arc-shaped, rectangular, or square. However, from the viewpoint of preventing a decrease in electrical connection reliability due to minute foreign matter being trapped between the bumps or between the bumps and the pads when joining a pair of electronic elements, a semicircular or approximately semicircular cross-sectional shape of the bump is particularly preferred. This also applies when the adhesive film of this embodiment contains a filler.

[0046] The adhesive film of this embodiment is not particularly limited in terms of its constituent materials as long as it is made of a thermosetting resin composition, but it preferably contains at least a thermosetting resin and a thermoplastic resin. Furthermore, the adhesive film of this embodiment and its cured product used for manufacturing semiconductor devices with excellent electrical connection reliability are non-conductive.

[0047] (A) Thermosetting Resin Any known thermosetting resin can be used as the thermosetting resin without any particular limitation. For example, polyphenylene ether resin, polyimide resin, maleimide resin, etc. can be used. Furthermore, the thermosetting resin blended into the thermosetting resin composition may be a single type, or two or more types may be used in combination. Among these thermosetting resins, polyphenylene ether resin is preferred from the viewpoints of the dielectric properties, heat resistance, and mechanical properties of the cured product of the adhesive film, as well as the electrical connection reliability of semiconductor devices manufactured using the adhesive film. Examples of polyphenylene ether resins include modified polyphenylene ether resins modified by introducing reactive groups such as styrene groups or methacrylic groups into the molecular terminals. Examples include styrene-modified polyphenylene ether resins (commercially available products include, for example, OPE-2st-1200 and OPE-2st-2200 manufactured by Mitsubishi Gas Chemical Company), and methacrylic-modified polyphenylene ether resins (commercially available products include, for example, Noryl SA-9000 manufactured by SABIC Corporation). Furthermore, from the viewpoint of ensuring and improving the formability of the adhesive film and ensuring and improving the solubility in the solvent contained in the coating liquid used to form the adhesive film, the number average molecular weight of the polyphenylene ether resin and other thermosetting resins is preferably 500 to 5,000, more preferably 800 to 3,500, and even more preferably 1,000 to 2,500.

[0048] Furthermore, the content of the thermosetting resin relative to all resin components contained in the thermosetting resin composition is preferably 10% by mass to 65% by mass, more preferably 15% by mass to 60% by mass, and even more preferably 20% by mass to 50% by mass. Furthermore, the thermosetting resin preferably contains at least a polyphenylene ether resin, and more preferably contains a polyphenylene ether resin as the main component. Here, in this paragraph, "main component" means that the content of the thermosetting resin relative to the total amount of the thermosetting resin is 50% by mass or more. The content of the polyphenylene ether resin relative to all thermosetting resins contained in the thermosetting resin composition is preferably 70% by mass to 100% by mass, more preferably 90% by mass to 100% by mass, and most preferably 100% by mass. By blending the resin components as described above, it becomes easier to more reliably ensure the electrical connection reliability of semiconductor devices manufactured using the adhesive film.

[0049] (B) Thermoplastic Resin Any known thermoplastic resin can be used as the thermoplastic resin without any particular limitations. For example, styrene-based elastomers, acrylic rubbers, fluororesins, etc. can be used. The thermoplastic resin blended into the thermosetting resin composition may be a single type or a combination of two or more types. Among these thermoplastic resins, styrene-based elastomers are preferred from the viewpoint of the dielectric properties and heat resistance of the cured adhesive film. Commercially available styrene-based elastomers include, for example, "Tuftec H1221" (hydrogenated styrene-based thermoplastic elastomer) manufactured by Asahi Kasei and "TR2003" (styrene-based thermoplastic elastomer) manufactured by ENEOS Materials Corporation.

[0050] The content of the thermoplastic resin relative to all resin components contained in the thermosetting resin composition is preferably 35 to 90% by mass, more preferably 40 to 85% by mass, and even more preferably 50 to 80% by mass. The thermoplastic resin preferably contains at least a styrene-based elastomer, and more preferably contains the styrene-based elastomer as the main component. In this paragraph, the term "main component" means that the content of the styrene-based elastomer relative to the total amount of thermoplastic resin is 50% by mass or more. The content of the styrene-based elastomer relative to all thermoplastic resins contained in the thermosetting resin composition is preferably 70 to 100% by mass, more preferably 90 to 100% by mass, and most preferably 100% by mass.

[0051] (C) Other Components In addition to the resin material, the thermosetting resin composition constituting the adhesive film may also contain, as necessary, fillers, curing catalysts, reducing agents, ion trapping agents, leveling agents, antioxidants, antifoaming agents, flame retardants, colorants, reactive diluents, etc. The content ratio of the other components (total amount) to be added to the thermosetting resin composition is not particularly limited and can be selected appropriately depending on the type of other components and the purpose of use, but is usually preferably more than 0% by mass and not more than 20% by mass, more preferably more than 0% by mass and not more than 10% by mass, and even more preferably more than 0% by mass and not more than 5% by mass.

[0052] Here, "filler" refers to a material that (i) is particulate and (ii) does not dissolve in or soften the remaining components of the thermosetting resin composition that constitutes the adhesive film, excluding the filler, or react with the remaining components. Representative examples include inorganic fillers, organic fillers, and organic-inorganic composite fillers made of a composite material of an organic material and an inorganic material. Furthermore, even if a material is not labeled as a "filler," in other words, a material that is originally used for purposes other than filler, if the material satisfies the conditions (i) and (ii) above, it is included in the term "filler." Examples of such materials include titanium oxide, which is used as a white pigment.

[0053] In addition, when a pair of electronic elements are bonded, if the adhesive film hardens with the filler present between the electrodes, it may cause a decrease in electrical connection reliability. In particular, when the gap length formed between a pair of electronic elements is reduced in order to narrow the pitch between the electrodes or shorten the wiring distance, the filler, like minute foreign matter, may enter the gap between the pair of electronic elements, easily causing a decrease in the electrical connection reliability of the semiconductor device. From this perspective, it is preferable that the thermosetting resin composition constituting the adhesive film does not contain any filler. Even if the thermosetting resin composition contains a filler, in order to suppress a decrease in electrical connection reliability, the content thereof is preferably more than 0% by mass and not more than 5% by mass, more preferably more than 0% by mass and not more than 2% by mass, and even more preferably more than 0% by mass and not more than 1% by mass. From the same viewpoint, the volume average particle diameter D95 (the particle diameter that is the cumulative 95% from the smallest diameter side in the volume-based particle size distribution) of the filler contained in the thermosetting resin composition is preferably 0.2 times or less, more preferably 0.1 times or less, the thickness of the adhesive film, and in the case where the filler is a monodisperse filler that does not have a particle size distribution, the particle diameter of the filler is preferably 0.2 times or less, more preferably 0.1 times or less, the thickness of the adhesive film.

[0054] Known curing catalysts can be used, and specific examples include organic peroxides, inorganic peroxides, azo compounds, and imidazole compounds. From the viewpoint of the reactivity of the thermosetting resin, organic peroxides or imidazole compounds are preferred as curing catalysts. Examples of organic peroxides include dicumyl peroxide, di(2-t-butylperoxyisopropyl)benzene, t-butylcumyl peroxide, and benzoyl peroxide. Examples of imidazole compounds include imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, and 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole.

[0055] In producing the adhesive film of this embodiment, a coating liquid is used in which the components constituting the adhesive film are dissolved in a solvent. The solvent can be appropriately selected depending on the solubility of each component constituting the adhesive film (excluding insoluble components such as fillers). Examples of the solvent include methylcyclohexane, cyclohexanone, and methyl ethyl ketone (MEK). Two or more solvents can be used in combination as needed. The content of the solvent in the coating liquid is not particularly limited as long as it can be appropriately selected so as to adjust the viscosity of the coating liquid to a level suitable for application processing. Generally, the content is preferably 50% to 90% by mass, and more preferably 40% to 80% by mass.

[0056] The coating solution described above is then applied to one side of a substrate film (such as a polyethylene terephthalate (PET) film with release treatment on both sides) to form a coating layer, and this coating layer is dried to form an adhesive film. Known coating methods, such as knife coating, gravure coating, and die coating, can be used as the coating method. The drying conditions for the coating layer can be appropriately selected depending on the drying device used, the boiling point and content of the solvent contained in the coating solution, the thickness of the coating layer, and the like. For example, when the coating layer is dried using a drying oven, the drying temperature can be 80°C to 120°C, and the drying time can be 5 to 20 minutes. It is usually preferable to attach a protective film (such as a PET film with release treatment on both sides) to the surface of the adhesive film after drying. For this reason, when using the adhesive film of this embodiment, it is usually preferable to provide it in the form of a multilayer film including the adhesive film, such as a laminate in which a substrate film, an adhesive film, and a protective film are laminated in this order. In this case, in the manufacturing process of a semiconductor device using the adhesive film of this embodiment, films other than the adhesive film (base film, protective film, etc.) are peeled off from the multilayer film at an appropriate timing.

[0057] Next, a semiconductor device manufactured using the adhesive film of this embodiment and a method for manufacturing the same will be described below.

[0058] The semiconductor device of the first embodiment includes a first semiconductor element having an electrode, a second semiconductor element having an electrode directly connected to an electrode of the first semiconductor element, and a cured product of the adhesive film of the present embodiment disposed between the first semiconductor element and the second semiconductor element. Here, "direct connection" means that the electrode of the first semiconductor element and the electrode of the second semiconductor element are electrically connected in direct contact without the use of wire wiring or the like. In addition, in the semiconductor device of the first embodiment, at least one of the electrodes provided on the first semiconductor element and the electrode provided on the second semiconductor element is a bump, but the other electrode may be either a bump or a pad.

[0059] The semiconductor device of the first embodiment is manufactured through at least a bonding step and a heating and pressing step, which will be described below.

[0060] Bonding step: The bonding step is a step of bonding the adhesive film of the present embodiment to the electrode arrangement surface of the first semiconductor element on which the electrodes are arranged. In the bonding step, for example, the adhesive film can be bonded to the electrode arrangement surface of the first semiconductor element using a laminator or the like.

[0061] Heating and Pressurizing Process: The heating and pressing process is a process of heating and pressing a laminate in which a first semiconductor element, an adhesive film, and a second semiconductor element are stacked in this order. Here, the laminate is formed by contacting (bonding) the surface of the adhesive film opposite the side on which the first semiconductor element is arranged with the electrode-arrangement surface on which the electrodes of the second semiconductor element are arranged, so that the electrodes of the first semiconductor element and the second semiconductor element face each other. The heating and pressing process is generally performed using a flip-chip bonder. The heating conditions can be appropriately selected to ensure that the adhesive film is cured and that bonding occurs between the electrodes due to interdiffusion of the metal material. For example, the heating temperature can be around 250°C to 300°C, and the heating time can be appropriately selected between several seconds and several minutes.

[0062] After the heating and pressing step is completed, various post-processing steps (for example, dicing, back grinding, formation of a rewiring layer, etc.) can be carried out as needed. When the semiconductor device of the first embodiment is a semiconductor device in which semiconductor elements are three-dimensionally integrated, the laminating step and the heating and pressing step are counted as one cycle, and this cycle can be repeated multiple times, and other steps can be carried out as needed between each cycle.

[0063] The semiconductor device of the second embodiment includes a semiconductor element having an electrode, a circuit board having an electrode, the electrode being directly connected to the electrode of the semiconductor element, and a cured product of the adhesive film of the embodiment disposed between the semiconductor element and the circuit board. Here, "direct connection" means a state in which the electrode of the semiconductor element and the electrode of the circuit board are electrically connected in direct contact without the use of wires or the like. In the semiconductor device of the second embodiment, at least one of the electrodes provided on the semiconductor element and the electrode provided on the circuit board is a bump, but the other electrode may be either a bump or a pad.

[0064] The semiconductor device of the second embodiment is also manufactured through at least a bonding step and a heating and pressurizing step, but in this case, each step can be carried out in two types of embodiments (first embodiment or second embodiment) described below.

[0065] First Embodiment In the first embodiment, the laminating step and the heating and pressurizing step are carried out in the following procedure.

[0066] Bonding process: The bonding process is a process of bonding the adhesive film of this embodiment to the electrode placement surface of the semiconductor element on which the electrodes are arranged. As in the case of manufacturing the first semiconductor device of this embodiment, the adhesive film can be bonded to the electrode placement surface of the semiconductor element using a laminator or the like.

[0067] Heating and pressurizing step: The heating and pressurizing step is a step of heating and pressurizing a laminate in which a semiconductor element, an adhesive film, and a circuit board are laminated in this order. Here, the laminate is formed by contacting (bonding) the surface of the adhesive film opposite the side on which the semiconductor element is arranged with the electrode arrangement surface on which the electrodes of the circuit board are arranged, so that the electrodes of the semiconductor element and the electrodes of the circuit board face each other. The heating and pressurizing treatment can be carried out in the same manner as in the case of manufacturing the semiconductor device of the first embodiment.

[0068] Second Embodiment In the second embodiment, the laminating step and the heating and pressurizing step are carried out in the following procedure.

[0069] Bonding process: The bonding process is a process of bonding the adhesive film of this embodiment to the electrode arrangement surface of the circuit board on which the electrodes are arranged, and the adhesive film can be bonded to the electrode arrangement surface of the circuit board using a laminator or the like, as in the case of manufacturing the first semiconductor device of this embodiment.

[0070] Heating and pressurizing step: The heating and pressurizing step is a step of heating and pressurizing a laminate in which a semiconductor element, an adhesive film, and a circuit board are laminated in this order. Here, the laminate is formed by contacting (bonding) the surface of the adhesive film opposite to the side on which the circuit board is arranged with the electrode arrangement surface on which the electrodes of the semiconductor element are arranged, so that the electrodes of the circuit board and the electrodes of the semiconductor element face each other. The heating and pressurizing treatment can be carried out in the same manner as in the case of manufacturing the semiconductor device of the first embodiment.

[0071] In the first and second embodiments, after the heating and pressurizing process is completed, various post-processes (for example, dicing, back grinding, formation of a rewiring layer, etc.) can be appropriately carried out as needed.

[0072] The applications of the semiconductor devices of the first and second embodiments are not particularly limited, but examples thereof include semiconductor memories, logic semiconductors, and various semiconductor sensors such as image sensors.

[0073] Specific examples of the present invention will be described below with reference to examples, but the present invention is not limited to the examples described below.

[0074] 1. Preparation of Coating Solution for Producing Adhesive Films The components listed below as raw materials for the coating solution for producing adhesive films were mixed and dissolved to give the compositions shown in Table 1, thereby preparing the coating solutions for producing adhesive films of each of the Examples and Comparative Examples.

[0075] (A) Thermosetting Resin A1: Styrene-modified polyphenylene ether resin (manufactured by Mitsubishi Gas Chemical Company, OPE-2st-1200) A2: Styrene-modified polyphenylene ether resin (manufactured by Mitsubishi Gas Chemical Company, OPE-2st-2200) A3: Aminophenol-type epoxy resin (manufactured by Mitsubishi Chemical Company, jER630)

[0076] (B) Thermoplastic Resins B1: Styrene-based thermoplastic elastomer (H1221, manufactured by Asahi Kasei) B2: Styrene-based thermoplastic elastomer (TR2003, manufactured by ENEOS Materials) B3: Phenoxy resin (YX8100BH30, manufactured by Mitsubishi Chemical; solid content 30% by mass, solvent (cyclohexanone and MEK) content: 70% by mass) B4: Styrene-based thermoplastic elastomer (8004, manufactured by Kuraray)

[0077] (C) Other Components Curing catalyst: acrylate-imidazole adduct curing agent (manufactured by ADEKA, EH2021)

[0078] Solvents: Methylcyclohexane, Cyclohexanone, MEK (Methyl Ethyl Ketone)

[0079]

[0080] 2. Preparation of Multilayer Film Including Adhesive Film A coating film was formed by applying, using a knife coater, a coating solution for forming an adhesive film having the composition of each Example and Comparative Example shown in Table 1 to one side of a PET film (substrate film) whose both surfaces had been treated for release. Next, the coating film formed on the PET film was placed in an oven and dried at 110°C for 10 minutes to form an adhesive film having the composition and thickness shown in Table 2. After forming the adhesive film, a PET film whose both surfaces had been treated for release was attached to the surface of the adhesive film as a protective film, thereby preparing a multilayer film in which the PET film (substrate film), adhesive film, and PET film (protective film) were laminated in this order.

[0081] It should be noted that, when the coating liquid of Comparative Example 2 was used, an adhesive film could not be formed. The coating liquid used to prepare the adhesive film of Comparative Example 2 had a solid composition excluding the solvent, containing 80 mass% thermosetting resin A1 and 20 mass% thermoplastic resin B1. The thermosetting resin A1, which accounts for the majority of the solid content, is a hard solid at 25°C. For this reason, when a film was formed on a substrate film using the coating liquid, only a hard and brittle film could be formed, and a continuous film having a consistent thickness in the horizontal direction and free of defects such as breaks, cracks, and chips could not be formed.

[0082] 3. Evaluation Results Table 2 shows the connection resistance values ​​evaluated using the adhesive films of each Example and Comparative Example, as well as the adhesive film composition, thickness, width of the temperature range showing a melt viscosity of 50,000 Pa s or less in the temperature range from above 90° C. to below 200° C., minimum melt viscosity V1 in the temperature range from above 90° C. to below 200° C., melt viscosity V2 at 200° C., and melt viscosity ratio (V2 / V1). Table 2 also shows the melt viscosity at 120° C. for reference.

[0083]

[0084] 4. Measurement and Evaluation Methods The thickness of the adhesive film, the width of the temperature range in which the film exhibits a melt viscosity of 50,000 Pa s or less in the temperature range of more than 90°C and less than 200°C, the minimum melt viscosity V1, the melt viscosity V2, and the melt viscosity at 120°C shown in Table 2, and the method for measuring the connection resistance are as follows:

[0085] 4.1 Thickness of adhesive film Using a contact film thickness meter, the thickness Tt of the multilayer film, the thickness T1 of the base film used in producing the multilayer film, and the thickness T2 of the protective film used in producing the multilayer film were each measured. The value obtained by subtracting the thickness T1 and the thickness T2 from the thickness Tt was then determined as the thickness of the adhesive film.

[0086] 4.2 Minimum melt viscosity V1, melt viscosity V2, melt viscosity at 120°C, and width of the temperature range showing a melt viscosity of 50,000 Pa·s or less in the temperature range greater than 90°C and less than 200°C of the adhesive film. The melt viscosity was measured using the following procedure. First, the base film and protective film were peeled off from the multilayer film to obtain an adhesive film, which was then folded to a thickness of 240 μm to prepare a measurement sample. Next, this measurement sample was sandwiched between a pair of parallel plates (diameter: 5 mm), and the melt viscosity was measured using an ARES-G2 rheometer (manufactured by TA Instruments). The measurement conditions for melt viscosity measurement were set to a load of 100 g, a measurement temperature range of 30°C to 200°C, a heating rate of 20°C / min, and a frequency of 1 Hz. From the measurement results, the minimum melt viscosity V1 (Pa s) in the temperature range greater than 90°C and less than 200°C, the melt viscosity V2 (Pa s) at 200°C, and the melt viscosity at 120°C were determined. In addition, from the graph of melt viscosity versus temperature obtained in measuring the minimum melt viscosity V1, the melt viscosity V2, and the melt viscosity at 120°C, the width of the temperature range showing a melt viscosity of 50,000 Pa s or less in the temperature range greater than 90°C and less than 200°C was determined. Note that when the melt viscosity was too high to measure, the melt viscosity value in Table 2 was expressed as ∞.

[0087] 4.3 Connection Resistance Value (1) Preparation of Measurement Samples The connection resistance value was measured by the following procedure: First, semiconductor elements X1, Y1, X2, and Y2 having the following specifications were prepared as wafer-shaped semiconductor elements. <Semiconductor element X1> Electrode type and material: Au bump (cross-sectional shape: square, bump height: 0.5 μm) Electrode planar shape and size: circular (diameter 0.5 μm) Electrode pitch: 1 μm <Semiconductor element Y1> Electrode type and material: Sn bump (cross-sectional shape: arc, bump height: 0.5 μm) Electrode planar shape and size: circular (diameter 0.5 μm) Electrode pitch: 1 μm <Semiconductor element X2> Electrode type and material: Au bump (cross-sectional shape: rectangular, bump height: 0.5 μm) Electrode planar shape and size: circular (diameter 2.0 μm) Electrode pitch: 4 μm <Semiconductor element Y2> Electrode type and material: Sn bump (cross-sectional shape: arc, bump height: 0.5 μm) Electrode planar shape and size: circular (diameter 2.0 μm) Electrode pitch : 4 μm

[0088] Next, after peeling the protective film from the multilayer film, the surface of the multilayer film on which the adhesive film was provided was attached to the electrode placement surface of semiconductor element X1, and then the base film was peeled from the adhesive film attached to the electrode placement surface of semiconductor element X1. Then, with the center points of the Au bumps on the semiconductor element X1 and the Sn bumps on the semiconductor element Y1 aligned so as to coincide with each other, the surface of semiconductor element X1 on which the adhesive film was attached and the electrode placement surface of semiconductor element Y1 were attached to form a laminate, and the laminate was then heated and pressurized using a flip-chip bonder. The heating and pressurizing conditions at this time were a temperature of 250°C and a pressure of 300 kg / cm. ２ This resulted in a measurement sample (electrode pitch = 1 μm) in which the semiconductor element X1, a cured product layer made of the cured product of the adhesive film, and the semiconductor element Y1 were laminated in this order.

[0089] Furthermore, using semiconductor elements X2 and Y2 instead of semiconductor elements X1 and Y1, a measurement sample (electrode pitch = 4 μm) was obtained in the same procedure as in the case of preparing the measurement sample (electrode pitch = 1 μm), in which the semiconductor element X2, a cured product layer made of the cured product of the adhesive film, and the semiconductor element Y2 were laminated in this order.

[0090] Except for Comparative Example 2, in which a film could not be formed, the adhesive films of each Example and Comparative Example were heat-treated at the same temperature as the heating and pressurizing conditions using a flip-chip bonder, and the degree of hardening of the obtained cured products was examined by visual observation, etc., and it was confirmed that all of the cured products were sufficiently hardened.

[0091] (2) Measurement of Connection Resistance Value Next, the connection resistance value of the measurement sample, i.e., the connection resistance value of the connection portion between the Au bump and the Sn bump, was measured using a four-terminal measurement method. A multimeter (MLR21, manufactured by ETAC) was used for the measurement, and measurements were performed at 13 locations on one measurement sample. The average connection resistance values ​​measured at each measurement location are shown in Table 2. From the viewpoint of electrical connection reliability, a connection resistance value of 60 Ω or less is considered preferable, and the smaller the value, the more desirable it is. When the connection resistance value was too high to measure, the connection resistance value was indicated as ∞ in Table 2.

Claims

1. An adhesive film used for bonding semiconductor elements together or for bonding semiconductor elements to circuit boards, the temperature range in which the film exhibits a melt viscosity of 50,000 Pa·s or less in the temperature range from greater than 90°C to less than 200°C is 40°C or more and less than 110°C, and the ratio (V2 / V1) of the melt viscosity V2 at 200°C to the minimum melt viscosity V1 in the temperature range from greater than 90°C to less than 200°C exceeds 1.

0.

2. The adhesive film according to claim 1, wherein the melt viscosity V2 is 8000 Pa·s or more.

3. The adhesive film according to claim 1 or 2, having a thickness of 0.5 μm to 6 μm.

4. The adhesive film according to any one of claims 1 to 3, having a thickness of 0.5 µm to 2.5 µm.

5. The adhesive film according to any one of claims 1 to 4, wherein the circuit board is a silicon substrate having a circuit formed thereon, or a glass substrate having a circuit formed thereon.

6. An adhesive film according to any one of claims 1 to 5, wherein the material constituting the surface of the electrode provided on the semiconductor element is a metal material containing at least one element selected from the group consisting of Au and Sn as its main component.

7. The adhesive film according to any one of claims 1 to 6, wherein the maximum diameter of the electrodes provided on the semiconductor element is 0.5 µm to 5 µm.

8. The adhesive film according to any one of claims 1 to 7, wherein the electrodes provided on the semiconductor element have an inter-electrode pitch of 0.5 µm to 5 µm.

9. An adhesive film according to any one of claims 1 to 8, wherein the material constituting the surface of the electrode provided on the circuit board is a metal material containing at least one element selected from the group consisting of Au and Sn as a main component.

10. The adhesive film according to any one of claims 1 to 9, wherein the maximum diameter of the electrodes provided on the circuit board is 0.5 µm to 5 µm.

11. The adhesive film according to any one of claims 1 to 10, wherein the electrodes provided on the circuit board have an inter-electrode pitch of 0.5 μm to 5 μm.

12. The adhesive film according to any one of claims 1 to 11, comprising a thermosetting resin and a thermoplastic resin.

13. The adhesive film according to any one of claims 12, wherein the thermosetting resin contains a polyphenylene ether resin as a main component.

14. The adhesive film according to claim 12 or 13, wherein the thermoplastic resin contains a styrene-based elastomer as a main component.

15. The adhesive film according to any one of claims 1 to 14, which does not contain a filler.

16. A semiconductor device comprising: a first semiconductor element having an electrode; a second semiconductor element having an electrode directly connected to an electrode of the first semiconductor element; and a cured product of the adhesive film according to any one of claims 1 to 15, disposed between the first semiconductor element and the second semiconductor element.

17. A method for manufacturing a semiconductor device, comprising: a step of attaching an adhesive film according to any one of claims 1 to 15 to an electrode placement surface on which an electrode of a first semiconductor element is arranged; and a step of heating and pressurizing a laminate in which the first semiconductor element, the adhesive film, and the second semiconductor element are laminated in this order by bringing a surface of the adhesive film opposite the side on which the first semiconductor element is arranged into contact with the electrode placement surface on which the electrodes of the second semiconductor element are arranged, so that the electrodes of the first semiconductor element and the electrodes of the second semiconductor element face each other.

18. A semiconductor device comprising: a semiconductor element having an electrode; a circuit board having an electrode directly connected to an electrode of the semiconductor element; and a cured product of the adhesive film according to any one of claims 1 to 15, disposed between the semiconductor element and the circuit board.

19. A method for manufacturing a semiconductor device, comprising: a step of attaching an adhesive film according to any one of claims 1 to 15 to an electrode placement surface on which an electrode of a semiconductor element is arranged; and a step of heating and pressurizing a laminate in which the semiconductor element, the adhesive film, and the circuit board are laminated in this order by bringing the surface of the adhesive film opposite the side on which the semiconductor element is arranged into contact with the electrode placement surface on which the electrodes of the circuit board are arranged, so that the electrodes of the semiconductor element and the electrodes of the circuit board face each other.

20. A method for manufacturing a semiconductor device, comprising: a step of attaching an adhesive film according to any one of claims 1 to 15 to an electrode placement surface on which an electrode of a circuit board is arranged; and a step of contacting a surface of the adhesive film opposite the side on which the circuit board is arranged with the electrode placement surface on which the electrodes of the semiconductor element are arranged, so that the electrodes of the circuit board and the electrodes of the semiconductor element face each other, thereby heating and pressurizing a laminate in which the semiconductor element, the adhesive film, and the circuit board are laminated in this order.

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