JP2012097281A - Filmy adhesive and production method of semiconductor device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filmy adhesive which can lower the temperature of chip loading and to conduct a flip chip connection method using ultrasonic vibration by the reduction of melting viscosity, and to provide a production method of a semiconductor device using this.SOLUTION: The filmy adhesive comprises: (a) a resin whose weight average molecular weight is larger than 10,000 and which is a solid form at ordinary temperature (25°C); (b) an insulating spherical inorganic filler; (c) an epoxy resin; and (d) a curing agent, wherein the minimum melting viscosity is 200 Pa×s or less at a temperature of 50-250°C, and the mean coefficient of linear expansion of a cured article is 200×10/°C at 25-260°C or lower. The production method of a semiconductor device uses this filmy adhesive.

Description

  The present invention relates to a film adhesive and a method for manufacturing a semiconductor device using the same.

  With the recent progress in downsizing and functional compounding of electronic devices, a form in which a plurality of semiconductor chips are mounted in one semiconductor package has been widely used. As a mounting form, it is possible to reduce the size of a semiconductor package by stacking chips three-dimensionally and electrically connecting them by wire bonding, rather than a method of arranging a plurality of chips two-dimensionally on a substrate. The so-called chip stack technology is widely applied. In this chip stack, an upper chip and a lower chip are bonded with an adhesive, and a paste or film adhesive is used. However, since the paste adhesive has a high fluidity, the chip electrode may be contaminated by the adhesive that protrudes at the time of bonding. Therefore, it is more common to use a film adhesive.

  On the other hand, flip chip connection technology that directly connects a semiconductor chip having protruding connection terminals (bumps) and a substrate electrode as a semiconductor chip connection technology corresponding to further miniaturization, thinning, and high-speed transmission has attracted attention. ing. Using flip chip connection technology, 1) it is not necessary to consider the wire loop height as in wire bonding, and 2) the size of the semiconductor package can be reduced due to the fact that the substrate electrode can also be arranged in the chip mounting area. Thinning is possible, and application to the above-described chip stack technology is being studied. As a flip chip connection technique, a semiconductor chip is formed by using a C4 method (for example, see Non-Patent Document 1) for electrically connecting a solder bump formed on a semiconductor chip and a wiring pattern on the substrate side, and using an anisotropic conductive adhesive resin. A method of electrically connecting the bumps formed on the substrate and the wiring pattern on the substrate side via conductive particles (see, for example, Non-Patent Document 2), a state in which the bumps formed on the semiconductor chip and the wiring pattern on the substrate side are in contact with each other The method of curing the thermosetting adhesive resin and maintaining the contact state by the shrinkage force (see Non-Patent Document 3, for example), after aligning the bump formed on the semiconductor chip and the wiring pattern on the substrate side, There is known a method of applying ultrasonic vibration from a metal and joining the metal (for example, see Non-Patent Document 4). Among these, the flip chip connection method by metal bonding using ultrasonic vibration is 1) that bumps and wiring patterns can be metal bonded at low temperature (room temperature to 200 ° C.), and 2) connection is required. Features that the time is 1 second or less, a method that realizes high thermal reliability by reducing the thermal stress by reducing the connection temperature, high connection reliability by forming metal joints, and high productivity by short-time connection It is attracting attention as. There has been an example applied to flip chip connection of a small chip such as a SAW (Surface Acoustic Wave) filter to a ceramic substrate (see, for example, Patent Document 1), but the space between the semiconductor chip and the substrate is filled with resin. It was limited to cases where underfill was unnecessary. On the other hand, taking advantage of the above-described advantages, application to the connection of a larger chip and a resin substrate is also being studied, but underfill is essential for ensuring connection reliability. However, the method of filling the liquid resin after the chip and the substrate are connected requires a long time, which may lead to a decrease in productivity.

Japanese Patent Laid-Open No. 08-330880

Hideo Aoki, and four others, "Eutectic Solder Flip Chip Technology-Bumping and Assembly Process Development for CSP / BGA", 47th Electronic Component and Technology Conference, the United States, Institute of Electrical and Electronics Engineers, 5 May 1997, p. 325-330 Shinichi Fujiwara and 4 others, “Degradation mechanism of flip chip connection using anisotropic conductive film and connection reliability design technology”, 7th Symposium on Microjoining and Assembly Technology in Electronics, Japan Welding Society Microjoining Research Committee, February 2001, p. 179-184 Hidenobu Nishikawa, 4 others, “Flip Chip Joining Technology Using Resin Encapsulated Sheet”, 6th Symposium on Microjoining and Assembly Technology in Electronics, Japan Welding Society Microjoining Research Committee, February 2000, p. 107-110 Ryoichi Sugawara, 5 others, “Ultrasonic flip chip bonding technology for multi-pin LSI chips”, 7th Symposium on Microjoining and Assembly Technology in Electronics, Japan Welding Society Microjoining Research Committee, February 2001, p. 161-166

  In order to stack a plurality of chips in a thin package, the thickness of the chip is reduced, and it is necessary to use a chip of 100 μm or less. However, since a chip is mounted by heating and pressing on a resin substrate using a thermosetting adhesive, there is a problem that the chip is warped when the temperature is returned to room temperature, and the chip cannot be further laminated. In order to solve this problem, it is required to lower the chip mounting temperature. However, film adhesives generally have a higher melt viscosity when heated than pastes or liquid adhesives, so at low temperatures the resin does not sufficiently adhere to the chip surface (low wettability) and adhesive strength decreases. There was a problem. In addition, by using a film adhesive for the flip chip connection method, it is possible to simplify the process because an underfill can be formed in the process of connecting the chip and the substrate, but flip chip connection using ultrasonic vibration is possible. Under low temperature and short time connection conditions in the system, the resin could not be removed from between the bump and the substrate electrode, and connection could not be made.

  Accordingly, the present invention provides a film-like adhesive that can cope with a reduction in chip mounting temperature and a flip-chip connection method using ultrasonic vibration by lowering the melt viscosity, and a semiconductor device using the same The object is to provide a manufacturing method.

The invention described in claim 1 is a film-like adhesive having the following components (a) to (d) as essential components, and has a minimum melt viscosity of 200 Pa · s or less at any temperature of 50 to 250 ° C. An average linear expansion coefficient of the cured product at 25 to 260 ° C. is 200 × 10 ⁻⁶ / ° C. or less.
(A) a resin having a weight average molecular weight of greater than 10,000 and solid at room temperature (25 ° C.);
(B) an insulating spherical inorganic filler,
(C) epoxy resin,
(D) Curing agent The invention described in claim 2 is characterized in that, in claim 1, the resin having a weight average molecular weight of greater than 10,000 and solid at room temperature (25 ° C.) has a fluorene skeleton. It is a film adhesive.
The invention described in claim 3 is the film adhesive according to claim 1 or 2, wherein the filling amount of the insulating spherical inorganic filler is 25 to 80% by weight. It is.
Invention of Claim 4 WHEREIN: In the film adhesive in any one of Claim 1 thru | or 3, the minimum melt viscosity of 200 Pa.s or less is 30 seconds or more at any temperature of 50-250 degreeC. It is a film-like adhesive characterized by holding.
According to a fifth aspect of the present invention, there is provided a step of attaching the film adhesive according to any one of the first to fourth aspects to a substrate on which a wiring pattern is formed, a connection terminal of a semiconductor chip having a protruding connection terminal The step of aligning the wiring pattern of the substrate and the substrate, applying ultrasonic vibration in a heated and pressurized state, electrically connecting the protruding connection terminal of the semiconductor chip and the wiring pattern of the substrate by metal bonding and the semiconductor A method for manufacturing a semiconductor device, comprising: a step of bonding a chip and a substrate with a film-like adhesive; and a step of performing a heat treatment so that a curing reaction rate of the film-like adhesive is 80% or more.
According to a sixth aspect of the present invention, there is provided a step of attaching a semiconductor chip having a connection terminal projecting the film adhesive according to any one of the first to fourth aspects to a surface on which the connection terminal is formed, a semiconductor chip The process of aligning the connection terminals of the board and the wiring pattern of the board, electrically connecting the protruding connection terminals of the semiconductor chip and the wiring pattern of the board by metal bonding by applying ultrasonic vibration in a heated and pressurized state And a step of adhering the semiconductor chip and the substrate with a film-like adhesive, and a step of performing a heat treatment so that the curing reaction rate of the film-like adhesive is 80% or more. It is.
According to a seventh aspect of the present invention, the film adhesive according to any one of the first to fourth aspects is affixed to a semiconductor wafer having projecting connection terminals, and is divided into individual semiconductor chips by dicing. A step of aligning the connection terminal of the semiconductor chip and the wiring pattern of the substrate, applying ultrasonic vibration in a heated and pressurized state, and connecting the protruding connection terminal of the semiconductor chip and the wiring pattern of the substrate by metal bonding A method for manufacturing a semiconductor device, comprising: a step of electrically connecting; and a step of performing a heat treatment in order to increase the curing reaction rate of the film adhesive to 80% or more.

  By using the film adhesive of the present invention, it is possible to form a good metal joint even under low temperature and short time connection conditions such as a flip chip connection method using ultrasonic vibration, and good connection reliability. Can be realized.

It is a side view explaining the method to evaluate the adhesiveness by the flip chip connection system using ultrasonic vibration. It is a side view explaining the manufacturing method of the semiconductor device by the flip chip connection system using an ultrasonic vibration.

  The film-like adhesive of the present invention comprises (a) a resin having a weight average molecular weight of greater than 10,000 and being solid at room temperature (25 ° C.), (b) an insulating spherical inorganic filler, (c) an epoxy resin, and (d) curing. Contains an agent as an essential component.

The minimum melt viscosity of the film adhesive is 200 Pa · s or less, and more preferably 100 Pa · s or less. The temperature exhibiting the minimum melt viscosity is any temperature within the range of 50 to 250 ° C, and is preferably within the range of 50 to 200 ° C in consideration of the correspondence to the low temperature connection conditions, and is preferably 50 to 160 ° C. It is more preferable to be within the range. The viscosity of the film adhesive can be measured using a commercially available dynamic viscoelasticity measuring apparatus, and the measurement is performed fully automatically. When a sample is sandwiched between two parallel plates in a thermostatic chamber heated to a predetermined temperature, and a minute sinusoidal twist distortion is applied to one plate, the elastic modulus and strain are determined from the stress and strain generated on the other plate. Calculate the viscosity. Generally, the measurement frequency is 0.5 to 10 Hz, and the polymer material behaves as a viscoelastic body, so that a storage elastic modulus G ′ derived from an elastic component and a loss elastic modulus G ″ derived from a viscous component are obtained. From the two values, the complex elastic modulus G * is given by (Equation 1). Further, when the viscosity is η (Pa · s), the measurement frequency is f (Hz), and the complex elastic modulus G ^* (Pa), the viscosity is ( It is given by equation 2).

  Usually, in a manufacturing process of a semiconductor device, after mounting a chip on a substrate having a plurality of chip mounting areas, a method of dividing the chip into individual pieces is generally used. Since the heat history is different in each mounting region, the curing reaction of the film adhesive starts and the viscosity may increase before chip connection. Therefore, it is more desirable that a viscosity of 200 Pa · s or less can be maintained for 30 s or more, and it is further desirable that the viscosity can be maintained for 60 s or more.

The average linear expansion coefficient at 25 to 260 ° C. of the cured product of the film adhesive is 200 × 10 ⁻⁶ / ° C. or less, preferably 150 × 10 ⁻⁶ / ° C. or less, and 100 × 10 ⁻⁶ / ° C. The following is more desirable. If it exceeds 200 × 10 ⁻⁶ / ° C., the connection reliability may be reduced.

  Examples of the resin (a) having a weight average molecular weight larger than 10,000 and solid at room temperature (25 ° C.) used in the present invention include epoxy resin, phenoxy resin, polyimide resin, polyamide resin, polycarbodiimide resin, phenol resin, and cyanate. Examples include ester resins, acrylic resins, polyester resins, polyethylene resins, polyethersulfone resins, polyetherimide resins, polyvinyl acetal resins, urethane resins, and acrylic rubbers. Among them, epoxy resins and phenoxys that are excellent in heat resistance and film formability. Resins, polyimide resins, cyanate ester resins, polycarbodiimide resins, and the like are desirable, and epoxy resins, phenoxy resins, and polyimide resins are more preferable. These may be used alone or as a mixture or copolymer of two or more. Particularly preferred is a phenoxy resin having a fluorene skeleton in the molecule, and the Tg is about 90 ° C., which is higher than that of other phenoxy resins (Tg about 60 ° C.). The heat resistance can be expected to improve. The weight average molecular weight is more than 10,000, desirably 20,000 or more, more desirably 30,000 or more, and if it is less than 10,000, the film forming ability may be lowered.

  Examples of the insulating spherical inorganic filler (b) used in the present invention include glass, silica, alumina, titanium oxide, carbon black, mica, etc. Among them, glass, silica, alumina, titanium oxide and the like are preferable. Glass, silica, and alumina are more preferable. These can be used alone or as a mixture of two or more. In addition, when the same kind of insulating spherical inorganic filler is blended in the same part by weight, the larger the particle size, the lower the melt viscosity. However, when the film adhesive of the present invention is applied to the flip chip connection method, the insulating spherical spherical filler is used. In order to prevent the inorganic filler from being trapped between the electrodes and hindering electrical connection, the particle size is desirably 10 μm or less.

  The (c) epoxy resin used in the present invention is a bifunctional or higher bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolak type epoxy resin, biphenyl type epoxy. Resin, naphthalene type epoxy resin, phenol aralkyl type epoxy resin, dicyclopentadiene type epoxy resin, various polyfunctional epoxy resins, and the like can be used. These can be used individually or in mixture of 2 or more types. The epoxy resin can be used in a liquid state or a solid state at 25 ° C.

  As the curing agent (d) used in the present invention, imidazoles, polyhydric phenols, acid anhydrides, amines, hydrazides, polymercaptan, Lewis acid-amine complexes and the like can be used. Among them, imidazoles, polyhydric phenols, acid anhydrides and the like that are excellent in storage stability and heat resistance of the cured product are desirable, and imidazoles and polyhydric phenols are more desirable. These can be used alone or as a mixture of two or more. It is also desirable to have a gelation time that does not initiate the curing reaction until the viscosity of the adhesive is sufficiently reduced. When the curing agent is an imidazole, 2P4MHZ, 2PHZ, 2MA-OK (trade names manufactured by Shikoku Kasei Kogyo Co., Ltd.) and the like can be cited as examples having sufficient pot life and gelation time. In addition, those encapsulating these curing agents with a polyurethane-based or polyester-based polymer substance and making them into microcapsules are preferable because the pot life is extended.

  In the present invention, the blending amount of the resin (a) having a weight average molecular weight of greater than 10,000 and solid at normal temperature (25 ° C.) is (a) a resin having a weight average molecular weight of greater than 10,000 and solid at normal temperature (25 ° C.), b) Insulating spherical inorganic filler, (c) The total amount of epoxy resin is preferably 5 to 30 parts by weight, more preferably 5 to 25 parts by weight, and more preferably 5 to 20 parts by weight. It is particularly preferable that If the blending amount is less than 5 parts by weight, film formation tends to be difficult, and if it exceeds 30 parts by weight, the viscosity may not be 200 Pa · s or less.

  The blending amount of the (b) insulating spherical inorganic filler in the present invention is (a) a resin having a weight average molecular weight of more than 10,000 and solid at room temperature (25 ° C.), (b) an insulating spherical inorganic filler, and (c) an epoxy. The amount is preferably 25 to 80 parts by weight and more preferably 25 to 65 parts by weight with respect to 100 parts by weight of the total resin. If the blending amount is less than 25 parts by weight, the coefficient of thermal expansion after curing tends to increase. If the blending amount exceeds 80 parts by weight, the viscosity may not be 200 Pa · s or less, and the flexibility of the film is reduced. There is a tendency to become brittle.

  The blending amount of (c) epoxy resin in the present invention is as follows: (a) resin whose weight average molecular weight is greater than 10,000 and is solid at room temperature (25 ° C.), (b) insulating spherical inorganic filler, (c) total amount of epoxy resin The amount is preferably 10 to 50 parts by weight and more preferably 20 to 45 parts by weight with respect to 100 parts by weight. If the blending amount is less than 10 parts by weight, the heat resistance of the cured product tends to decrease, and if it exceeds 50 parts by weight, the thermal expansion coefficient of the cured product tends to increase. In addition, when (a) resin whose weight average molecular weight is larger than 10,000 and is solid at normal temperature (25 ° C.) is an epoxy resin, the blending amount is calculated as (c) epoxy resin.

  The blending amount of (d) curing agent in the present invention varies depending on the type of curing agent, but when the curing agent is an imidazole, it is 0.1 to 20 parts by weight with respect to 100 parts by weight of (c) epoxy resin. It is desirable to make it 1-10 parts by weight. If this amount is less than 0.1 parts by weight, curing will be insufficient. Moreover, when it exceeds 20 weight part, hardened | cured material physical property may fall.

  In addition to the above essential components, a silane-based or titanium-based coupling agent can be used for the film adhesive of the present invention. As this usage-amount, it is preferable that it is 0.1-10 weight part with respect to 100 weight part of (b) insulating spherical inorganic fillers.

The substrate electrically connected to the semiconductor chip may be a normal circuit substrate or a semiconductor chip. In the case of a circuit board, the wiring pattern is formed by etching away unnecessary portions of a metal layer such as copper formed on the surface of an insulating substrate such as glass epoxy, polyimide, polyester, and ceramic. Those formed and those formed by printing a conductive substance on the surface of the insulating substrate can be used. Moreover, the wiring pattern does not need to be composed of a single metal, and may contain a plurality of metal components such as gold, silver, copper, nickel, indium, palladium, tin, lead, and bismuth. You may have the structure where the metal layer was laminated | stacked.
When the substrate is a semiconductor chip, the wiring pattern is usually made of aluminum, but a metal layer such as gold, silver, copper, nickel, indium, palladium, tin, lead, or bismuth is formed on the surface by plating. May be.

  The protruding connection terminals of the semiconductor chip are the ones in which stud bumps or metal balls formed using metal wires are fixed to the electrodes of the semiconductor chip by thermal heating / pressurization or ultrasonic heating / pressurization, plating, vapor deposition It may be formed by. The protruding connection terminal may be composed of a single metal such as gold, silver, copper, nickel, indium, palladium, tin, lead, bismuth, or may include a plurality of metal components. You may have the structure where the metal layer was laminated | stacked. The protruding connection terminal may be formed by printing a conductive paste.

In order to affix the film adhesive to the region on the substrate surface where the semiconductor chip is mounted, the adhesive film cut into individual pieces may be disposed in the affixing region and adhered by heating and pressing.
The position and area for applying the film adhesive is arbitrary within the region where the semiconductor chip is mounted, but it is attached so as to cover at least part of the wiring pattern electrically connected to the protruding connection terminal of the semiconductor chip. It is preferable to attach.

  In order to affix the film adhesive to the semiconductor chip having the protruding connection terminals, the adhesive film cut out into individual pieces may be affixed by heating and pressing. Moreover, after sticking a film adhesive in the state of a semiconductor wafer with a roll laminator etc., you may cut out into a piece as a semiconductor chip to which the film adhesive was stuck by dicing.

After the film adhesive is applied to the surface of the substrate on which the semiconductor chip is mounted or the surface on which the protruding connection terminal of the semiconductor chip is formed, the semiconductor chip and the substrate may be connected as they are. In order to reduce the volatile components in the agent and the circuit board and suppress the generation of bubbles called voids between the semiconductor chip and the substrate, it is preferable to heat-treat with the film adhesive applied. . Moreover, since the viscosity of a film adhesive falls by heat-processing, the embedding property to a wiring pattern is improved and the void generation by bubble entrainment can be reduced.
When performing the heat treatment, it is desirable to perform the treatment at a temperature lower than the curing reaction start temperature of the film adhesive used or shorter than the reaction start time.
The curing reaction start temperature may be obtained from the intersection of the tangent line and the baseline of the exothermic curve before reaching the exothermic peak in the chart obtained by DSC (Differential Scanning Calorimeter), or the viscosity and heating temperature. The temperature at which the viscosity starts to rise may be obtained by plotting the above relationship.
The curing reaction start time may be obtained by plotting the relationship between the processing time of the sample heat-treated at a predetermined temperature and the calorific value obtained by DSC, and obtaining the time until the calorific value starts decreasing, or the viscosity and processing The time until the viscosity starts to rise may be obtained by plotting the time relationship.

In order to electrically connect the semiconductor chip and the substrate, an apparatus having a mechanism for fixing the substrate to the stage, fixing the semiconductor chip to a bonding head attached in parallel with the ultrasonic vibration direction, and pressing the bonding head from above is used. . Such an apparatus is commercially available, and for example, an ultrasonic flip chip bonder SH-50MP (product name) manufactured by Altex Co., Ltd. can be used.
The conditions for connecting the semiconductor chip and the substrate are as follows: connection temperature: 50 to 250 ° C., pressure: 0.1 to 10 MPa, ultrasonic frequency: 20 to 200 kHz, vibration amplitude: 0.01 μm or more, pressurization time: The application time of ultrasonic waves is within a range of 0.1 seconds or more and 0.05 seconds or more, and the timing of pressurization and ultrasonic application starts ultrasonic application within the pressurization time, If it is satisfied that the application of the sound wave is completed, it may be applied at an arbitrary timing.
If the connection temperature is less than 50 ° C., the adhesive resin remains between the bump and the wiring pattern, and there is a possibility that the connection is not connected or the connection resistance is increased. When the connection temperature exceeds 250 ° C., the thermal stress derived from the difference in thermal expansion coefficient between the semiconductor chip and the substrate increases, and the connection portion may be damaged. In the case of a resin substrate, the substrate may be softened and ultrasonic vibrations may be absorbed, preventing metal bonding. More preferably, it is the range of 50-200 degreeC.
If the pressure is less than 0.1 MPa, the resin may remain between the connecting terminals facing each other, which may result in disconnection or increase in connection resistance. If the pressure exceeds 10 MPa, the connection terminals and wiring are destroyed. There is a risk of being. More preferably, it is the range of 0.3-4.0 MPa.
If the frequency of the ultrasonic wave is less than 20 kHz, the connection terminals and wiring may be destroyed. If the frequency exceeds 200 kHz, ultrasonic vibrations are not transmitted to the connection part, and the resin remains between the connection terminals facing each other. However, there is a possibility that the connection resistance becomes high due to the lack of connection or insufficient metal bonding. More preferably, it is the range of 40-100 kHz.
If the amplitude of the ultrasonic vibration is less than 0.01 μm, the resin remains between the connecting terminals facing each other and is not connected, or the diffusion resistance of the metal is insufficient, resulting in an increase in connection resistance or connection reliability. May decrease. More preferably, it is the range of 0.1-10 micrometers.
If the pressurization time is less than 0.1 seconds, resin may remain between the opposing connection terminals, which may result in disconnection or increase in connection resistance, or decrease in connection reliability. Since the productivity decreases as the time increases, it is necessary to shorten the pressurization time. Preferably it is within 10 seconds.
If the application time of the ultrasonic wave is less than 0.05 seconds, the metal surface is insufficiently removed due to insufficient removal of organic substances and oxides on the metal surface, resulting in insufficient metal bonding, high connection resistance, and low connection reliability. There is a case. Further, when the amplitude is increased or the frequency is decreased, if the application time is lengthened, the connection terminal or the wiring may be destroyed. More preferably, it is within 5 seconds, and if it exceeds 5 seconds, the productivity may be lowered.

High connection reliability by electrically connecting the protruding connection terminals of the semiconductor chip and the wiring pattern on the substrate surface and then heat-treating (after-cure) so that the curing reaction rate of the film adhesive is 80% or more. Sex can be secured. It is more preferable to perform heat treatment so that the curing reaction rate is 90% or more.
In order to perform the heat treatment so that the curing reaction rate becomes 80% or more, it may be left on a heat stage or in a heating oven. This heat treatment process can be performed on a plurality of semiconductor devices at once.
The heat treatment is preferably performed at a temperature higher than the curing start temperature, but immediately after the semiconductor chip and the substrate are connected, the curing reaction rate of the film adhesive is 80% or less, so it is left in a high temperature atmosphere rapidly. As a result, thermal stress derived from the difference in thermal expansion coefficient between the semiconductor chip and the substrate may be concentrated on the connection portion and damage to the connection portion may occur. More preferably, heating is started from a temperature lower than the curing start temperature, and the treatment is performed at a heating temperature of at least two stages.
The curing reaction rate of the thermosetting resin can be measured by DSC (Differential Scanning Thermal Analysis). DSC is based on the zero principle method of supplying or removing the amount of heat so as to cancel out the temperature difference from the standard sample that does not generate heat or endotherm within the measurement temperature range. Measurement can be performed automatically. The curing reaction of a thermosetting resin such as an epoxy resin is an exothermic reaction, and when the sample is heated at a constant temperature increase rate, the sample reacts to generate reaction heat. The amount of heat generation is output to a chart, and the area of the region surrounded by the heat generation curve and the base line is defined as the amount of heat generation based on the baseline. The measurement is performed in a range that sufficiently covers the temperature at which the curing reaction is completed from room temperature. For example, in the case of an epoxy resin, measurement is performed at a temperature increase rate of 5 to 20 ° C./min from room temperature to 250 ° C., and the above-described heat generation amount is obtained. The curing reaction rate of the thermosetting resin is determined as follows. First, the total calorific value of the uncured sample is measured, and this is defined as A (J / g). Next, the calorific value of the measurement sample is measured, and this is defined as B. The degree of cure C (%) of the measurement sample is given by the following formula 3.

また、熱硬化性樹脂としてエポキシ樹脂を用いた場合には、可視レーザ励起のラマン分光計や近赤外レーザ励起のラマン分光計等で測定したエポキシ基のラマンスペクトルのピーク強度や面積強度を用いて反応硬化率を評価することもできる（例えば、特開２０００−１７８５２２公報参照）。

In addition, when an epoxy resin is used as the thermosetting resin, the peak intensity or area intensity of the Raman spectrum of the epoxy group measured with a visible laser-excited Raman spectrometer or near-infrared laser-excited Raman spectrometer is used. The reaction curing rate can also be evaluated (see, for example, JP 2000-178522 A).

(Examples 1-5)
The following phenoxy resin was used as a resin having a weight average molecular weight greater than 10,000 and solid at room temperature (25 ° C.) and having a fluorene skeleton. The phenoxy resin includes 4,4 ′-(9-fluorenylidene) -diphenol and each diglycidyl ether derivative (2,5-bis (t-butyl) hydroquinone diglycidyl ether, or 2,2′-dimethyl-5,5. '-Bis (t-butyl) -diphenol sulfide diglycidyl ether or 3,3', 5,5'-tetramethylbiphenol diglycidyl ether) is dissolved in N-methylpyrrolidone, and potassium carbonate is added to the solution. In addition, the mixture was stirred at 110 ° C. for 3 hours and then synthesized by dropping the precipitate formed by dropwise addition into a large amount of methanol. Phenoxy resin using 2,5-bis (t-butyl) hydroquinone diglycidyl ether (A), 2,2′-dimethyl-5,5′-bis (t-butyl) -diphenol sulfide diglycidyl ether The phenoxy resin used was (B), and the phenoxy resin using 3,3 ′, 5,5′-tetramethylbiphenol diglycidyl ether was used as (C) to prepare a film adhesive. The phenoxy resin (A) can be obtained as FX281S (trade name, manufactured by Toto Kasei Co., Ltd.), and the phenoxy resin (C) can be obtained as FX293S (trade name, manufactured by Toto Kasei Co., Ltd.).
The film adhesive was produced by the following procedure.

  Phenoxy resin YP50S (trade name, manufactured by Tohto Kasei Co., Ltd.) as a resin having a weight average molecular weight greater than 10,000 and solid at room temperature (25 ° C.), Phenoxy resin (A) having a fluorene skeleton (FX281S, manufactured by Toto Kasei Co., Ltd.) Name), the above resins (B), (C) (FX293S, product name manufactured by Toto Kasei Co., Ltd.), polyfunctional epoxy resin EP1032H60 (product name manufactured by Japan Epoxy Resin Co., Ltd.) as an epoxy resin, bisphenol A type liquid epoxy resin EP828 (Product name manufactured by Japan Epoxy Resin Co., Ltd.), 2P4MHZ and 2PHZ (product names manufactured by Shikoku Kasei Kogyo Co., Ltd.) as solid imidazole, silica filler SE2050 (product name manufactured by Admatechs Co., Ltd.) as insulating inorganic filler 0.4-0. 6μm), SE6050 (manufactured by Admatechs Co., Ltd., product name average particle size 1.5 to 2.5 μm), and dissolved in a toluene-ethyl acetate mixed solvent with the composition shown in Table 1 to produce a varnish. After apply | coating this varnish on a separator film (PET film) using a roll coater, the film adhesive was produced by making it dry in 70 degreeC oven for 10 minutes.

(Comparative Examples 1-3)
Phenoxy resin YP50S (product name, manufactured by Tohto Kasei Co., Ltd.) as a resin having a weight average molecular weight greater than 10,000 and solid at room temperature (25 ° C.), Phenoxy resin (C) having a fluorene skeleton (FX293S, manufactured by Tohto Kasei Co., Ltd.) Name), polyfunctional epoxy resin EP1023H60 (product name manufactured by Japan Epoxy Resin Co., Ltd.) as an epoxy resin, bisphenol A type solid epoxy resin EP1007 (product name manufactured by Japan Epoxy Resin Co., Ltd.), bisphenol A type liquid epoxy resin EP828 (Japan Epoxy) Resin Co., Ltd. product name), 2P4MHZ, 2PHZ (product names made by Shikoku Kasei Kogyo Co., Ltd.) as solid imidazole, HX-3941HP (product name made by Asahi Kasei Co., Ltd.) as a microcapsule type curing agent, insulating inorganic Using silica filler SE2050 (product name, average particle size 0.4 to 0.6 μm, manufactured by Admatechs Co., Ltd.) as a filler, a varnish was prepared by dissolving in a toluene-ethyl acetate mixed solvent with the composition shown in Table 1. The varnish was applied on a separator film (PET film) using a roll coater, and then dried in an oven at 70 ° C. for 10 minutes to prepare a film adhesive.

  The melt viscosity was measured using a viscoelasticity measuring device ARES manufactured by Rheometrics Scientific F.E. The measurement plate was a parallel plate having a diameter of 8 mm, the film adhesive was laminated, and a 500 to 600 μm thick plate was cut into a size of 9 mm × 9 mm. Measurement conditions were set to a temperature of 150 ° C. and a frequency of 10 Hz.

  As a cured sample of the film adhesive, a sample treated under heating conditions of 100 ° C.−2h + 125 ° C.−1h + 150 ° C.−1h + 200 ° C.−1h was prepared (thickness 50 μm). The average linear expansion coefficient was measured using a TMA / SS6000 (product name) manufactured by Seiko Instruments Inc., and a cured sample was cut into a size of 2 mm × 25 mm, a distance between chucks of 15 mm, a measurement temperature range of 20 to 300 ° C., The heating rate was 5 ° C./min, and the tensile load was 0.5 MPa with respect to the film cross-sectional area. For measurement of Tg (tan δ peak), a cured sample was cut into a size of 0.5 mm × 45 mm using a DMS6100 (product name) manufactured by Seiko Instruments Inc., a distance between chucks of 20 mm, a frequency of 1 Hz, and a measurement temperature range of 20 It carried out on the conditions of -300 degreeC and the temperature increase rate of 5.0 degree-C / min.

  The following evaluation was performed to evaluate the bondability. Using the above film adhesive, after affixing to a glass epoxy substrate having a wiring pattern plated with Ni / Au, a semiconductor chip on which gold stud bumps are formed is formed by a flip chip connection method using ultrasonic vibration. Connected. A semiconductor chip having a size of 10.2 mm × 10.2 mm and 184 gold stud bumps formed in a peripheral arrangement is used. The head temperature is 150 ° C., the stage temperature is 50 ° C., the amplitude is 2.0 μm, and the frequency. The connection conditions of 50 kHz, application time 0.5 s, load 1.0 N / bump (pressure of 1.77 MPa with respect to the semiconductor chip) were set, and an ultrasonic flip chip bonder SH-50MP (product name) manufactured by Altex Co., Ltd. was used. Connected. About the connection sample, after measuring initial connection resistance, it immersed in 2-butanone, the film adhesive resin was melt | dissolved, and connection resistance was measured again. Furthermore, after immersing in hydrochloric acid or sodium hydroxide aqueous solution, the aluminum electrode of the semiconductor chip was dissolved and the semiconductor chip was removed, the number of gold bumps remaining on the wiring pattern was measured, and the bonding rate was calculated. (Joint rate = number of gold bumps remaining on the wiring pattern / total number of bumps 184). Next, a share test of the gold bumps remaining on the wiring pattern was performed. The shear test was performed using Daisy 2400 manufactured by Daisy, and was performed under conditions of room temperature (25 ° C.) and a shear rate of 200 μm / s.

  Connection reliability was evaluated according to the following procedure. Flip chip connection using ultrasonic vibration to a semiconductor chip on which gold stud bumps are formed after the film adhesive is pasted on a glass epoxy substrate having a wiring pattern that has been subjected to Ni / Au plating treatment and the separator film is peeled off Connected by the method. A semiconductor chip having a size of 10.2 mm × 10.2 mm and 184 gold stud bumps formed in a peripheral arrangement is used. The head temperature is 150 ° C., the stage temperature is 50 ° C., the amplitude is 2.0 μm, and the frequency. The connection conditions of 50 kHz, application time 0.5 s, load 1.0 N / bump (pressure of 1.77 MPa with respect to the semiconductor chip) were set, and an ultrasonic flip chip bonder SH-50MP (product name) manufactured by Altex Co., Ltd. was used. Connected. After the connection sample was treated under after-curing conditions of 100 ° C.-2h + 125 ° C.-1h + 150 ° C.-2h, the connection resistance was measured. At this time, the curing reaction rates of the film adhesives were all 90% or more. Next, the connection sample was left in an oven heated to 125 ° C. for 24 hours, then left in a constant temperature and humidity chamber adjusted to 30 ° C. and a relative humidity of 60% for 192 hours, and then IR reflow treatment (265 ° C. max) was performed three times. It was. The connection resistance of the connection sample after the reflow treatment was measured, and a resistance increase of 10% or less of the initial resistance was regarded as acceptable.

  Table 2 shows the results of the minimum melt viscosity measurement, the thermal expansion coefficient measurement of the cured product, and the result of the ultrasonic chip connection test.

  In the film adhesives of Examples 1 to 5 having a minimum melt viscosity at 150 ° C. of 200 Pa · s or less, 1) the initial resistance after chip connection is 2 mΩ / bump or less, and 2) dissolution of the adhesive In the flip-chip connection method using ultrasonic vibration, there is no open defect afterwards, 3) that the shear strength of the bump is high, and 4) that there is no defect due to moisture absorption reflow treatment. It can be seen that a good metal joint is formed and shows good connection reliability. On the other hand, Comparative Examples 1 to 3 whose minimum melt viscosity exceeds 200 Pa · s have high initial resistance after chip connection, high resistance after dissolution of the adhesive, open failure, and poor bonding rate. Also, the share strength is low and the connection reliability is inferior.

  The film adhesive in the present invention can be used not only as an underfill material in a flip chip connection method for directly connecting a protruding connection terminal of a semiconductor chip and a wiring pattern of a substrate, but also on a circuit forming surface of the semiconductor chip. In the wire bonding method in which the electrode of the semiconductor chip and the wiring pattern of the substrate are electrically connected with a gold wire or the like, and can be used as an adhesive for bonding the chip and the substrate. Further, in a stacked package in which semiconductor chips are stacked in multiple stages, it can also be used as an adhesive for bonding and fixing the semiconductor chip and the semiconductor chip.

1,10. 10. Glass epoxy substrate 2, 11. Wiring patterns 3, 12. Film adhesive 4,13. Tool 5,14. Stages 6 and 15. Semiconductor chip 7, 16. Aluminum electrodes 8, 17. Gold stud bump9. Share tool

Claims (7)

A film-like adhesive comprising the following (a) to (d) as essential components, having a minimum melt viscosity of 200 Pa · s or less at any temperature of 50 to 250 ° C., and a cured product at 25 to 260 ° C. A film-like adhesive having an average linear expansion coefficient of 200 × 10 ⁻⁶ / ° C. or less.
(A) a resin having a weight average molecular weight of greater than 10,000 and solid at room temperature (25 ° C.);
(B) an insulating spherical inorganic filler,
(C) epoxy resin,
(D) Curing agent   The film adhesive according to claim 1, wherein the resin having a weight average molecular weight of more than 10,000 and solid at normal temperature (25 ° C) has a fluorene skeleton.   The film adhesive according to claim 1 or 2, wherein a filling amount of the insulating spherical inorganic filler is 25 to 80% by weight.   The film adhesive according to any one of claims 1 to 3, wherein a minimum melt viscosity of 200 Pa · s or less is maintained for 30 seconds or more at any temperature of 50 to 250 ° C. adhesive.   A step of attaching the film adhesive according to any one of claims 1 to 4 to a substrate on which a wiring pattern is formed, aligning a connection terminal of a semiconductor chip having a protruding connection terminal and a wiring pattern of the substrate A step of applying ultrasonic vibration in a heated / pressurized state to electrically connect the protruding connection terminal of the semiconductor chip and the wiring pattern of the substrate by metal bonding, and the semiconductor chip and the substrate to a film adhesive A method of manufacturing a semiconductor device, comprising: a step of performing heat treatment so that the curing reaction rate of the film adhesive is 80% or more.   A step of applying the film-shaped adhesive according to any one of claims 1 to 4 to a surface on which a connection terminal of a semiconductor chip having a connection terminal protruding is formed, a connection terminal of the semiconductor chip, and a wiring pattern of the substrate In the process of aligning, by applying ultrasonic vibration in a heated / pressurized state, the protruding connection terminal of the semiconductor chip and the wiring pattern of the substrate are electrically connected by metal bonding and the semiconductor chip and the substrate are in a film form A method for manufacturing a semiconductor device, comprising: a step of bonding with an adhesive; and a step of performing a heat treatment so that a curing reaction rate of the film adhesive is 80% or more. A step of attaching the film adhesive according to any one of claims 1 to 4 to a semiconductor wafer having a protruding connection terminal, a step of dicing into individual semiconductor chips, a connection terminal and a substrate of the semiconductor chip A process of aligning the wiring pattern of the substrate, a process of electrically connecting the protruding connection terminal of the semiconductor chip and the wiring pattern of the substrate by metal bonding by applying ultrasonic vibration in a heated and pressurized state, a film shape A method for manufacturing a semiconductor device, comprising a step of performing a heat treatment so that a curing reaction rate of an adhesive is 80% or more.

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