JP2010132884A - Adhesive sheet and semiconductor element using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive sheet without intrusion of a sealing material into the interface of the adhesive sheet and a material to be adhered even when sealing a semiconductor element under high pressure, capable of eliminating a space without filling in pressure bonding and excellent in heat resistance and moisture resistance, and to provide the semiconductor element using the same. <P>SOLUTION: The adhesive sheet includes a resin composition without foaming at 200°C or lower by heating at 140°C for one minute, and exhibits improved adhesive force by heating at 140°C for one minute and then heating at 200°C for one minute on a Si base material coated with SiN and shows an adhesive force of 1.0 MPa or over determined at 180°C. The semiconductor element is produced using the same. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an adhesive sheet used for manufacturing a semiconductor element and a semiconductor element using the same.
More specifically, it is used when a chip is crimped and mounted on a lead frame or chip, and heat resistance that can disappear under high temperature and high pressure conditions at the time of sealing filling voids that could not be embedded only by crimp mounting The present invention relates to an adhesive sheet excellent in moisture resistance and a semiconductor element using the same.

  In recent years, stacked MCPs (Multi Chip Packages) in which chips are stacked in multiple stages have become widespread, and they are mounted as memory packages for mobile phones and mobile audio devices, for example.

  In such applications, with the increase in functionality of mobile phones and the like, higher density and higher integration of packages are promoted, and multi-stage chips and thinner packages are required. As a package that can satisfy such requirements, a package in which the chips are stacked in a staircase pattern with respect to the lower chip has been attracting attention.

Reliability is one of the important characteristics in the field of mounting substrates on which various electronic components such as stacked MCPs are mounted. For example, whether or not a chip can be mounted without generating a gap on the bonding surface is one factor that affects the bonding reliability.
In Patent Document 1, a semiconductor element that fits a semiconductor device manufacturing process and crimps a chip onto a substrate or a chip, and voids that could not be filled only by crimp mounting can be lost under high temperature and high pressure conditions in the sealing process. An adhesive sheet excellent in heat resistance and moisture resistance that can be produced is disclosed.

  In recent years, in the manufacture of semiconductor devices, there is a tendency to design the mold gap as low as possible in order to achieve a reduction in size and thickness of the semiconductor device. As a result, the sealing becomes incomplete, or voids are likely to remain in the sealing resin, which may be eliminated by setting the sealing process to a higher temperature and pressure.

JP 2002-220576 A

  When the elastic modulus of the adhesive sheet is low or the adhesive force with the adherend is low, sealing is performed using the adhesive sheet as a semiconductor element, and the sealing resin is the interface between the adhesive sheet and the adherend or the adhesive sheet. It becomes easy to enter inside. When the sealing material penetrates in this way, the circuit surface of the lower chip or the chip itself may be damaged, resulting in a defective semiconductor element.

  According to the adhesive sheet described in Patent Document 1, voids that could not be embedded only by crimping can be eliminated under high temperature and high pressure conditions in the sealing process. Both have low adhesive strength, and when sealing is performed at a high pressure, there is a problem that the sealing material enters. For this reason, development of the adhesive sheet which can respond to the sealing process at a high pressure is desired.

  The present invention has been made in view of the above-described problems, and even when a semiconductor element is sealed at a high pressure using an adhesive sheet as a semiconductor element, the sealing material enters the interface between the adhesive sheet and the adherend. It is an object of the present invention to provide an adhesive sheet excellent in heat resistance and moisture resistance and a semiconductor element using the same, which can eliminate voids that could not be filled during pressure bonding.

That is, the present invention is as follows.
(1) An adhesive sheet composed of a resin composition that does not foam at 200 ° C. or lower when heated at 140 ° C. for 1 minute, and is heated at 140 ° C. for 1 minute and then heated at 200 ° C. for 1 minute. Adhesive sheet with improved adhesion to the Si substrate coated with, and having an adhesion measured at 180 ° C. of 1.0 MPa or more.

(2) An adhesive sheet used in a method for producing a semiconductor element having a sealing step, which is composed of a resin composition and has a shear storage elastic modulus at 200 ° C. of 1 to 10 MPa after heating at 200 ° C. for 5 minutes. Adhesion that can completely adhere to the adherend by sealing the semiconductor element under the condition of 180 ° C./13 MPa / 90 seconds after heating at 140 ° C. for 1 minute and then at 200 ° C. for 5 minutes. Sheet.

(3) The resin composition has 100 parts by mass of a thermosetting resin, a crosslinkable functional group, a weight average molecular weight of 100 to 800,000, and a high molecular weight of Tg of −50 to 50 ° C. Containing 100 to 200 parts by mass of components, 50 to 150 parts by mass of an inorganic filler having an average particle size of 1.0 μm or less, and 0.20 to 0.80 parts by mass of a curing accelerator,
The adhesive sheet according to (1) or (2), wherein the thermosetting resin contains 15 to 50% by mass of a bifunctional epoxy resin that becomes liquid or softens at 70 ° C.

(4) The inorganic filler having an average particle size of 1.0 μm or less is a first inorganic filler in which 99% by mass or more is distributed in a range of 0.1 to 4.0 μm, and 99% by mass or more is 0.01%. The adhesive sheet according to any one of the above (1) to (3), comprising a second inorganic filler distributed in -1.0 µm.
(5) The adhesive sheet according to the above (1), wherein the adhesive force to the Si substrate coated with SiN is 2.0 MPa or more and the thickness is 5 to 250 μm.
(6) Using the adhesive sheet according to any one of (1) to (5) above, mounting a chip at 140 ° C./0.04 MPa / 1 second, before after heat or wire bonding after pressure bonding A semiconductor element manufactured in a sealing process of 180 ° C./13 MPa / 90 s by adding a heat history at 140 ° C. for 1 minute in the preheating process, followed by a wire bonding process at 200 ° C. or less and 5 minutes or less.

  Even when the adhesive sheet of the present invention is pressure-bonded and mounted, and the heat history in the process of the adhesive sheet is 200 ° C. or less and within 5 minutes, sealing is performed under the condition of 180 ° C./13 MPa / 90 seconds. In addition, it is possible to prevent the sealing material from entering the interface between the adhesive sheet and the adherend and the inside of the adhesive sheet, and to eliminate voids that could not be filled at the time of pressure bonding.

  Furthermore, since the adhesive sheet according to the present invention has excellent adhesive strength with respect to the Si substrate coated with SiN and is excellent in high heat resistance and high moisture resistance, the adhesive sheet can be used for reliability. It is possible to provide a semiconductor device having a high level.

It is the schematic which shows the state which pinched | interposed the adhesive sheet of this invention with the slide glass (cover glass).

Hereinafter, embodiments for carrying out the invention will be described in detail.
<Adhesive sheet>
The adhesive sheet which becomes this invention is comprised from the resin composition which can be in a completely hardened | cured material (C stage) state after a hardening process through a semi-hardened (B stage) state. The adhesive sheet according to the present invention does not foam at 200 ° C. or lower when heated at 140 ° C. for 1 minute, and improves the adhesion to SiN by heating at 140 ° C. for 1 minute and then at 200 ° C. for 1 minute. The adhesive strength measured at 180 ° C. to the Si substrate coated with SiN is 1.0 MPa or more.

In the present invention, “substrate coated with SiN” includes Si chips coated with SiN. More specifically, “SiN” is silicon nitride (Si ₃ N ₄ ).

Further, “heating at 140 ° C. for 1 minute and not foaming below 200 ° C.” specifically indicates the following state.
The adhesive sheet is punched into 10 mm squares, sandwiched between 18 mm square cover glasses (thickness 0.15 mm), and laminated on a hot plate at 60 ° C. so as to prevent bubbles from entering as shown in FIG.
This is set as an initial state, and the image is captured by a scanner (resolution: 300 pix) and stored. Thereafter, using a hot plate, the sample is heated at 140 ° C. for 1 minute, and the state after heating is captured and stored as an image with a scanner (resolution: 300 pix).
Next, the heat-treated sample is heated to 200 ° C. using a hot plate, and the state after being heated by the scanner is captured and stored as an image (resolution: 300 pix). The presence or absence of foaming is confirmed by comparing the state of the adhesive sheet before and after heating. Specifically, a case where the void ratio is less than 5 (area)% is defined as “not foamed”.

  Further, the shear storage modulus at 200 ° C. after heating at 140 ° C. for 1 minute and then at 200 ° C. for 5 minutes is 1 to 10 MPa, and the heat history in the process for the adhesive sheet is 200 ° C. or less, 5 Within minutes, when an adhesive sheet is used for a semiconductor element, it can be completely adhered to the adherend by sealing under the condition of 180 ° C./13 MPa / 90 seconds in the sealing step. And

“Completely in close contact with the adherend” is as follows.
First, the adhesive layer 20 μm of the adhesive sheet was attached to a semiconductor wafer having a thickness of 75 μm (please disclose the product name) at 60 ° C. Thereafter, they are diced into 7.5 mm squares to obtain chips. The adhesive layer of the separated chip is pressure-bonded on a substrate surface coated with a resist (trade name: “AUS308”, manufactured by Taiyo Ink Manufacturing Co., Ltd.) under conditions of 140 ° C., 0.04 MPa, 1 second. Get.
Next, the obtained sample is heated at 140 ° C. for 1 minute, and further a thermal history (200 ° C., 5 minutes) is given to the sample using a hot plate. Next, sealing is performed under conditions of 180 ° C./13 MPa / 90 seconds using a mold sealing material (manufactured by Hitachi Chemical Co., Ltd., trade name: “CEL-9700HF”), followed by 175 ° C. for 5 hours. A package is obtained by heating.
A part of the obtained package is analyzed by SAT and cross-sectional observation of the package to confirm the adhesion to the adherend.
When the void ratio is less than 15 area% by SAT and cross-sectional observation, it is assumed that the film is “completely in close contact with the adherend”.

In order to prevent the intrusion of the sealing material when sealed under the condition of 180 ° C./13 MPa / 90 seconds, at 180 ° C. (sealing temperature) after heating at 140 ° C. for 1 minute and 200 ° C. for 1 minute. It is important that the adhesive strength is 1.0 MPa, and more preferably 2.0 MPa or more. When the adhesive force at 180 ° C. after heating at 140 ° C. for 1 minute and 200 ° C. for 1 minute is less than 1.0 MPa, the sealing resin enters the interface between the adhesive sheet and the adherend in the sealing step. Tend.
In order to make the adhesive force at 180 ° C. to the substrate coated with SiN after heating at 140 ° C. for 1 minute and 200 ° C. for 1 minute to be 1.0 MPa or more, a specific thermosetting property will be described later. The resin content, the content of the first inorganic filler in which 99% by mass or more is distributed in the range of 0.1 to 4.0 μm, and the content of the curing accelerator may be set to a specific range. Each content will be described later.

The adhesion strength at 180 ° C. to the SiN-coated substrate after heating at 140 ° C. for 1 minute and 200 ° C. for 1 minute is measured as follows.
First, a sample adhesive sheet is attached to a 400 μm thick wafer at 60 ° C. and diced to 5.0 mm square. The chip with the adhesive sheet separated into pieces is pressure-bonded to the surface of the Si chip surface-treated with SiN under the condition of 140 ° C./100 gf / 1 second to produce a sample for measuring adhesive force.
Subsequently, it heated at 140 degreeC / 1 minute and 200 degreeC / 1 minute with the hotplate. The die shear strength is measured at 180 ° C. using the obtained test piece.

  In order to completely adhere to the adherend by sealing at 180 ° C./13 MPa / 90 seconds, shear storage at 200 ° C. after heating at 140 ° C. for 1 minute and then at 200 ° C. for 5 minutes. The elastic modulus is preferably 1 to 10 MPa, and more preferably 1 to 5 MPa. When the shear storage modulus at 200 ° C. after heating at 140 ° C. for 1 minute and then at 200 ° C. for 5 minutes exceeds 10 MPa, voids disappear even in a sealing process under a high pressure condition of 180 ° C./13 MPa / 90 s. It becomes difficult. On the other hand, when the pressure is less than 1 MPa, the sealing material resin tends to enter the interface between the adhesive sheet and the adherend.

The shear storage modulus at 200 ° C. after heating at 200 ° C. for 5 minutes is measured as follows.
Eight adhesive sheets having a thickness of 20 μm are stacked at 60 ° C. to obtain a sheet having a thickness of 160 μm. Next, the sheet is punched into a 10 mm square in the thickness direction.
Set a circular aluminum plate jig with a diameter of 8 mm in ARES (Rheometric Scientific), set the punched sample sheet here, heat at 140 ° C for 1 minute, and then raise the temperature to 200 ° C Shear storage modulus was measured every 8 seconds while applying 5% strain under plugram conditions, and the measured value after 5 minutes passed was “200 ° C. after heating at 200 ° C. for 5 minutes”. And

<Adhesive sheet material>
The resin composition constituting the adhesive sheet of the present invention includes a thermosetting resin, a high molecular weight component that appropriately adjusts the viscosity, flexibility, and the like, and an inorganic filler. As one embodiment of the resin composition used in the present invention, 100 parts by mass of a thermosetting resin, a crosslinkable functional group, a weight average molecular weight of 100 to 800,000, and Tg of −50 to 50 100 to 200 parts by mass of a high molecular weight component having a temperature of 50 ° C., 50 to 150 parts by mass of an inorganic filler having an average particle size of 1.0 μm or less, and 0.20 to 0.80 parts by mass of a curing accelerator In addition, the thermosetting resin includes an adhesive sheet containing 15% by mass or more of a bifunctional epoxy resin that becomes liquid or softens at 70 ° C., but may additionally contain additives, coupling agents, and the like. Hereinafter, each component will be described.
In the present invention, the content of the thermosetting resin, the content of the first inorganic filler in which 99% by mass or more is distributed in the range of 0.1 to 4.0 μm, and the content of the curing accelerator are specified. By setting the range, the adhesion force to the Si substrate coated with SiN is improved, and when the adhesive sheet is used for a semiconductor element, the semiconductor element is sealed under a sealing condition of 180 ° C./13 MPa / 90 seconds in the sealing step. When the is sealed, it is possible to obtain an adhesive sheet having good adhesion to the adherend.

  Moreover, it is more preferable that the inorganic filler includes a second inorganic filler in which 99% by mass or more is distributed in the range of 0.01 to 1.0 μm in addition to the first inorganic filler. When the content of the inorganic filler is 5 parts by mass or more with respect to 100 parts by mass of the thermosetting resin, the adhesive force after complete curing can be further increased. When the adhesive sheet is used for a semiconductor element, sealing is performed. When the semiconductor element is sealed under a sealing condition of 180 ° C./13 MPa / 90 seconds in the process, the adhesion to the adherend can be improved.

(Thermosetting resin)
The thermosetting resin preferably contains an epoxy resin and a phenol resin from the viewpoints of heat resistance and moisture resistance required when an element is mounted in the manufacture of a semiconductor device.

The epoxy resin is not particularly limited as long as it has an adhesive action by a curing treatment. For example, it is possible to use a bifunctional epoxy resin such as a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol S type epoxy resin, or a novolac type epoxy resin such as a phenol novolac type epoxy resin or a cresol novolac type epoxy resin. is there.
Moreover, it is also possible to use well-known epoxy resins, such as a polyfunctional epoxy resin, a glycidyl amine type epoxy resin, a heterocyclic ring-containing epoxy resin, or an alicyclic epoxy resin.

It is preferable that the thermosetting resin contains 15 to 50% by mass of the bifunctional epoxy resin that becomes liquid or softens at 70 ° C. with respect to the total amount of the thermosetting resin component. When it exceeds 50% by mass, the crosslink density after the heat treatment at 200 ° C. becomes low, the adhesive force is low, and the sealing material easily enters. On the other hand, if it is less than 15% by mass, the shear viscosity of the adhesive sheet in the B stage state is high, the fluidity at the time of crimping is deteriorated, and as a result of the decrease in the adhesive force due to insufficient wetting with the adherend, the adhesive sheet is made semiconductor. When used in an element, the sealing material easily enters in the sealing step. Although not particularly limited, bisphenol A type or bisphenol F type epoxy resin may be mentioned as a specific example of the bifunctional epoxy resin that becomes liquid or softens at 70 ° C.
The phrase “becomes liquid or softens at 70 ° C.” indicates a resin having a liquid or softening point of 70 ° C. or less at room temperature.

On the other hand, the phenolic resin is not particularly limited, but is preferably one having a low softening point from the viewpoint of meltability during heating. Specifically, the softening point is preferably 110 ° C. or lower.
Similarly, in the B-stage state, the lower the degree of crosslinking is, the better the meltability is, so that a phenol equivalent is preferable.

  The blending amount of the epoxy resin and the phenol resin in the thermosetting resin is preferably 0.70 / 0.30 to 0.30 / 0.70 in terms of an equivalent ratio of epoxy equivalent and hydroxyl equivalent. .65 / 0.35 to 0.35 / 0.65 is more preferable, 0.60 / 0.40 to 0.40 / 0.60 is further preferable, and 0.60 / 0.40. Most preferably, it is in the range of ˜0.50 / 0.50. When the blending ratio of each resin exceeds the upper limit value, the curability of the obtained adhesive sheet is lowered, or the viscosity of the adhesive sheet before the curing treatment becomes too high, and the fluidity tends to be inferior.

  As a more specific best mode, the thermosetting resin preferably contains an epoxy resin represented by the following general formula (1) and a phenol resin represented by the following general formula (2).

（式中、Ｒ_１〜Ｒ_５は直鎖、分岐又は環状アルキル基、アラルキル基、アルケニル基、水酸基、アリール基又はハロゲン原子を示し、ｋ及びｍは０〜４の整数、ｎは０〜３の整数を示し、繰り返し単位の数を示すｐは１〜５０の範囲の整数を示す。）

(Wherein R _{1 to} R ₅ represent a linear, branched or cyclic alkyl group, an aralkyl group, an alkenyl group, a hydroxyl group, an aryl group or a halogen atom, k and m are integers of 0 to 4, and n is 0 to 3) And p indicating the number of repeating units is an integer in the range of 1 to 50.)

The epoxy resin and phenol resin represented by the general formulas (1) and (2) are not particularly limited. However, among the corresponding resins, from the viewpoint of heat resistance and moisture resistance, the water absorption after being put into a constant temperature and humidity chamber at 85 ° C. and 85% RH for 48 hours is 2% by mass or less, respectively. It is preferable to use a resin having a heating mass reduction rate at 250 ° C. measured by an analyzer (TGA) of less than 5 mass% (temperature increase rate: 5 ° C./min, measured in a nitrogen atmosphere).
The water absorption is obtained by measuring the mass change at 85 ° C./85% RH.
The heating mass reduction rate can be measured using a suggested thermal analysis method.

Various resins represented by the above general formulas (1) and (2) can be obtained as commercial products. Specific examples of the epoxy resin represented by the general formula (1) include YDF series manufactured by Toto Kasei Co., Ltd. Further, specific examples of the phenol resin represented by the general formula (2) include Milex XLC-series and XL series manufactured by Mitsui Chemicals.
Further, they have a water absorption rate of 2% by mass or less and a heating mass reduction rate of less than 5% by mass.

(High molecular weight component)
The high molecular weight component used in the present invention is easy to cut at the time of wafer dicing, is difficult to produce resin waste, has high adhesive strength and heat resistance, and further exhibits high fluidity in an uncured state. Therefore, it is preferable that the glass transition temperature (Tg) is −50 to 50 ° C. and the weight average molecular weight is 100 to 800,000.

As the high molecular weight component, those having a Tg of −20 ° C. to 40 ° C. and a weight average molecular weight of 100 to 800,000 are more preferable, the Tg of −10 ° C. to 40 ° C., and the weight average molecular weight of 20 to 80 It is more preferable that it is 10,000.
Tg is a value measured using DSC (thermal differential scanning calorimeter) (for example, “Thermo Plus 2” manufactured by Rigaku Corporation).
The “weight average molecular weight” defined in the present invention indicates a polystyrene-converted value using a standard polystyrene calibration curve according to gel permeation chromatography (GPC).

  If the Tg of the high molecular weight component exceeds 50 ° C., the flexibility of the adhesive sheet may be lowered. On the other hand, if the Tg is less than −50 ° C., the flexibility of the adhesive sheet is too high, so that the adhesive sheet is difficult to cut during wafer dicing, and the dicing property may be deteriorated due to the generation of burrs.

  Moreover, when the weight average molecular weight of the high molecular weight component is less than 100,000, the adhesive sheet film formability may be deteriorated, and the adhesive strength and heat resistance of the sheet may be deteriorated. On the other hand, when the weight average molecular weight exceeds 800,000, the fluidity of the uncured adhesive sheet may be reduced, and when the adhesive sheet is used for a semiconductor element, the filling of the voids in the sealing process with the unevenness is incomplete. There is a possibility.

  In the present invention, the high molecular weight component is not particularly limited as long as it satisfies the above-mentioned characteristics, but a compound having a crosslinkable functional group in the molecule is preferable in order to exhibit high heat history. For example, polyimide resin, (meth) acrylic resin, urethane resin, polyphenylene ether resin, polyetherimide resin, phenoxy, each having a crosslinkable functional group such as epoxy group, alcoholic or phenolic hydroxyl group or carboxyl group in the molecule. High molecular weight components based on resins, modified polyphenylene ether resins and the like can be used.

  More specifically, it is obtained by copolymerizing a monomer compound having a crosslinkable functional group such as glycidyl acrylate or glycidyl methacrylate and a (meth) acrylic compound, and (Tg) is −50 to 50 ° C. An epoxy group-containing (meth) acrylic copolymer having a weight average molecular weight of 100 to 800,000 is mentioned, and it is preferable to use it.

  As a (meth) acrylic compound constituting such an epoxy group-containing (meth) acrylic copolymer, a derivative such as (meth) acrylic acid or an ester thereof or a copolymer thereof can be used.

  Especially, it is preferable to use the epoxy group containing acrylic rubber which has acrylic acid ester as a main component. Specific examples of the epoxy group-containing acrylic rubber include a copolymer of butyl acrylate and acrylonitrile, a copolymer of ethyl acrylate and acrylonitrile, and the like.

  The high molecular weight component used in the present invention can also be obtained as a commercial product. For example, a trade name “acrylic rubber HTR-860P” manufactured by Teikoku Chemical Industry Co., Ltd. may be mentioned. This compound has a glycidyl moiety as a crosslinkable functional group and is based on an acrylic rubber made of an acrylic acid derivative and has a weight average molecular weight of 800,000 and a glass transition temperature Tg (−7 ° C.).

(Filler)
The resin composition constituting the adhesive sheet of the present invention is improved in the dicing property of the adhesive sheet in the B-stage state, the handling property of the adhesive sheet, the thermal conductivity is improved, the melt viscosity is adjusted, and the thixotropic property is imparted. A filler is blended for the purpose of improving the adhesive strength.

  As the filler to be blended, an inorganic filler is preferable. Adhesion of the adhesive sheet at 180 ° C. before the sealing step after heat treatment at 140 ° C. for 1 minute and then at 200 ° C. for 1 minute by appropriately blending the inorganic filler with the above thermosetting resin and high molecular weight component The force can be adjusted to 1.0 MPa or more.

  In order to impart high fluidity to the adhesive sheet before the curing treatment and further impart appropriate meltability during the curing treatment, the inorganic filler is, for example, 50 to 150 parts by mass with respect to 100 parts by mass of the thermosetting resin. It is preferable to mix | blend in the ratio. When an excessive amount of inorganic filler is present in the resin composition, the elastic modulus before the sealing step increases, and the voids tend to be imperfectly filled during sealing.

  The average particle diameter of the inorganic filler is 1.0 μm or less, and 99% by mass thereof is preferably distributed in the range of 0.05 to 4.0 μm. An inorganic filler having an average particle diameter of 0.5 μm and 99% by mass distributed in the range of 0.05 to 1.0 μm is more preferable. When using an inorganic filler with an average particle size of less than 0.05 μm, the fluidity of the adhesive sheet decreases due to an increase in specific surface area and an increase in the number of contained particles, and embedding of voids tends to be incomplete during sealing. There is. On the other hand, when a filler having an average particle diameter exceeding 1.0 μm is used, the decrease in the contained particles may cause deterioration in film formability during sheet preparation.

  In addition, the inorganic filler is a first inorganic filler in which 99% by mass or more is distributed in the range of 0.1 to 4.0 μm, and a second inorganic filler in which 99% by mass or more is distributed in the range of 0.01 to 1.0 μm. More preferably, by containing 5 parts by mass or more with respect to 100 parts by mass of the thermosetting resin, the adhesive force after complete curing can be further increased, and the adhesive sheet can be used as a semiconductor element. When used, when the semiconductor element is sealed under a sealing condition of 180 ° C./13 MPa / 90 seconds in the sealing step, adhesion to the adherend can be improved.

  In the present invention, the average particle diameter of the filler is D50 measured by a light scattering method.

The inorganic filler that can be used in the present invention is not particularly limited, and examples thereof include aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, alumina, Examples thereof include aluminum nitride, aluminum borate whisker, boron nitride, crystalline silica, amorphous silica, and antimony oxide, and these can be used alone or in combination of two or more.
In order to improve thermal conductivity, alumina, aluminum nitride, boron nitride, crystalline silica, amorphous silica and the like are preferable.

  For the purpose of adjusting melt viscosity and imparting thixotropic properties, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, alumina, crystalline silica, non-crystalline silica Crystalline silica and the like are preferred. In order to improve dicing properties, alumina and silica are preferable.

(Curing accelerator)
For the purpose of promoting smooth curing of the adhesive sheet, the thermosetting resin is preferably contained in an amount of 0.20 to 0.80 parts by mass with respect to 100 parts by mass, and 0.40 to 0.70 parts by mass. It is more preferable to contain part. If the amount exceeds 0.80 parts by mass, the voids tend to be imperfectly filled during sealing. On the other hand, when it is less than 0.20 parts by mass, the adhesive sheet is not sufficiently cured in the heat history before sealing, and the sealing material easily enters in the sealing process.
The curing accelerator used in the present invention is not particularly limited, and examples thereof include imidazoles. Specific examples include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, and the like. Or in combination of two or more.

  In addition to the above-mentioned thermosetting resin, high molecular weight component, inorganic filler, and curing accelerator, the resin composition constituting the adhesive sheet contains various additives such as a catalyst, an additive, and a coupling agent as necessary. Further, it may be included. Although there is no restriction | limiting in particular, In order to improve the adhesive force with respect to a to-be-adhered body, it is preferable to contain a coupling agent.

<Method for producing adhesive sheet>
The adhesive sheet of the present invention comprises a thermosetting resin mainly composed of the above-mentioned epoxy resin, a high molecular weight component, an inorganic filler, a curing accelerator, and various additives selected as necessary in an organic solvent. Preparation by preparing a varnish-like resin composition by kneading, forming the varnish layer by coating it on the base film, and subsequently removing the base film after heating and drying the varnish layer Is possible.

  Mixing and kneading can be carried out by appropriately combining dispersers such as a normal stirrer, a raking machine, a three-roller, and a ball mill. The conditions for the above-described heat drying are not particularly limited as long as the organic solvent used is sufficiently volatilized and the shear viscosity at 110 ° C. is 30000 Pa · s or less. Usually, it implements by heating at 60 to 200 degreeC for 0.1 to 90 minutes.

  The substrate film to which the resin composition prepared as a varnish is applied is not particularly limited. For example, polyester film, polypropylene film, polyethylene terephthalate film, polyimide film, polyetherimide film, polyether naphthalate film, methylpentene film Etc. can be used.

The organic solvent that can be used when preparing the varnish is not particularly limited as long as each component can be uniformly dissolved and kneaded or dispersed, and a known organic solvent can be used. Specific examples of such solvents include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, dimethylformamide, dimethylacetamide, N methylpyrrolidone, toluene, xylene and the like.
It is preferable to use methyl ethyl ketone, cyclohexanone or the like as the organic solvent from the viewpoint that the drying speed is high and the cost is low.

The film thickness of the adhesive sheet is usually 5 to 250 μm for the purpose of developing sufficient adhesive force. When the film thickness is less than 5 μm, the stress relaxation effect and adhesiveness tend to be poor. On the other hand, when the film thickness exceeds 250 μm, it is not economical and it becomes difficult to meet the demand for downsizing of the semiconductor device.
In addition, the film thickness of the adhesive sheet is more preferably 5 to 100 μm, and more preferably 5 to 40 μm from the viewpoint that the adhesiveness is high and the semiconductor device can be thinned.

The adhesive sheet of the present invention preferably has a post-curing adhesive strength of 2.0 MPa or more with respect to an adherend such as a semiconductor substrate or a chip (specifically, a substrate coated with SiN).
More preferably, the adhesive strength to the SiN-coated substrate is 2.0 MPa or more and the thickness is 5 to 250 μm. Thereby, excellent heat resistance and moisture resistance can be realized.

<Use of adhesive sheet>
The adhesive sheet of the present invention can be used alone, but as an embodiment of the present invention, the adhesive sheet is laminated on a known dicing tape and used as a dicing / die bonding integrated adhesive sheet. It is also possible. By integrating the adhesive sheet and the dicing sheet in this manner, the laminating process on the wafer can be performed once, so that the manufacturing efficiency of the semiconductor element can be increased.

  Examples of the dicing tape that can be used in the present invention include plastic films such as a polytetrafluoroethylene film, a polyethylene terephthalate film, a polyethylene film, a polypropylene film, a polymethylpentene film, and a polyimide film. If necessary, the dicing tape may be subjected to surface treatment such as primer application, UV treatment, corona discharge treatment, polishing treatment, and etching treatment.

  The dicing tape preferably has adhesiveness, and the above-mentioned plastic film provided with adhesiveness may be used, or an adhesive layer may be provided on one side of the above-mentioned plastic film.

  Such a pressure-sensitive adhesive layer can be formed by applying a resin composition known as a pressure-sensitive adhesive layer to the surface of a plus chip film and then drying it. It is also possible to use the resin composition used for the adhesive sheet of the present invention, in which case, by adjusting the ratio of the epoxy resin that is a liquid component in the thermosetting resin and the Tg of the high molecular weight component, in particular, It is preferable that the resin composition has an appropriate tack strength.

When the adhesive sheet of the present invention is applied to the production of a semiconductor element, the adhesive sheet needs to have an adhesive force that prevents the semiconductor element from scattering during dicing, and to be peelable from the dicing tape during subsequent pickup.
For example, if the adhesive sheet is too sticky, picking up may be difficult.

  Therefore, it is preferable to appropriately adjust the tack strength of the adhesive sheet. As an adjustment method, decreasing the melt viscosity at room temperature (25 ° C.) of the adhesive sheet tends to increase the adhesive strength and tack strength, and increasing the melt viscosity tends to decrease the adhesive strength and tack strength. Can be used.

  More specifically, when lowering the melt viscosity, the content of the epoxy resin represented by the general formula (1) having a melting point / softening point of 70 ° C. or lower is increased, or a tackifier is added. Is adjustable by etc.

  On the other hand, when the melt viscosity is increased, the melt viscosity can be adjusted by decreasing the content of each compound.

  Examples of the method for laminating the adhesive sheet according to the present invention on the dicing tape include a printing method and a method in which an adhesive sheet prepared in advance is pressed or hot-roll laminated on the dicing tape. The hot roll laminating method is preferable because it can be continuously produced and is efficient.

  The film thickness of the dicing tape is not particularly limited, and can be appropriately set based on the knowledge of those skilled in the art depending on the film thickness of the adhesive sheet and the application of the dicing tape-integrated adhesive sheet. Although there is no particular limitation, a film thickness of 60 to 150 μm is preferable and a film thickness of 70 to 130 μm is more preferable in terms of good economic efficiency and good handleability of the sheet.

The adhesive sheet of this invention can be used for manufacture of a semiconductor element. In the adhesive sheet of the present invention, a chip is mounted at 140 ° C./0.04 MPa / 1 second by the adhesive sheet of the present invention, and a heat history of 140 ° C. for 1 minute is added in the preheating process after after-bonding or before wire bonding. Then, it is preferably used in a method for manufacturing a semiconductor element including a sealing step of 180 ° C./13 MPa / 90 seconds through a wire bonding step of 200 ° C. or less and within 5 minutes.
More specifically, in the method of manufacturing a semiconductor element according to the present invention, a wafer and an adhesive sheet are bonded to each other at 0 ° C. to 80 ° C., and then a laminated body of the wafer and the adhesive sheet is used using a rotary blade or a laser. After cutting to obtain a chip with an adhesive sheet, this chip with adhesive is mounted on the lead frame or on the chip by crimping at 140 ° C./0.04 MPa / 1 second before post-compression or wire bonding. In the preheating step, a heat history of 140 ° C. for 1 minute is added, followed by a wire bonding step of 200 ° C. or less within 5 minutes, the voids disappear in a sealing step of 180 ° C./13 MPa / 90 seconds, and the adherend It is possible to achieve complete adhesion.

  When the adhesive sheet of the present invention is used in the method for producing a semiconductor element by setting the shear storage elastic modulus to 1 to 10 MPa, the thermal history of the sealing step is 200 ° C. or less and within 5 minutes, It is possible to eliminate voids that could not be filled only by crimp mounting.

  When the adhesive sheet is used alone as described above, it is preferable that the dicing tape is subsequently bonded to the adhesive sheet surface after the wafer and the adhesive sheet are bonded together. Alternatively, a dicing / die bonding integrated adhesive sheet in which an adhesive sheet and a dicing tape are bonded in advance can be used. The wafer to be bonded to the adhesive sheet may be composed of single crystal silicon, polycrystalline silicon, various ceramics, compound semiconductors such as gallium arsenide, and the like.

  The temperature at which the adhesive sheet and the wafer are attached, that is, the laminating temperature, is usually preferably 0 to 90 ° C, more preferably 15 to 80 ° C, and further preferably 20 to 80 ° C. When the laminating temperature exceeds 90 ° C., the adhesive sheet may be excessively melted, so that the change in the thickness of the adhesive sheet may become significant. When the dicing tape or the dicing / die bonding integrated adhesive sheet is attached, it is preferably performed at the same temperature.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not restrict | limited to these.
(Examples 1-2 and Comparative Examples 1-2)
Each component was mixed with the composition shown in Table 1, and the varnish-like resin composition for forming an adhesive sheet was prepared, respectively. In addition, the unit of a composition shown in Table 1 is a mass part, and the detail of each component is as follows.

(Epoxy resin)
YDF-8170C (trade name, bisphenol F type epoxy resin manufactured by Toto Kasei Co., Ltd., epoxy equivalent 159, liquid at normal temperature, water absorption rate: 1% by mass, heating mass reduction rate: 4% by mass)
YDCN-700-10 (trade name, manufactured by Toto Kasei Co., Ltd., cresol novolac type epoxy resin, epoxy equivalent 210, softening point 75 to 85 ° C., water absorption rate 1 mass%, heating mass reduction rate: 4 mass%)

(Phenolic resin)
Phenolite LF-4871 (trade name, manufactured by Dainippon Ink Co., Ltd., phenol resin, hydroxyl group equivalent: 118, softening point: 130 ° C., water absorption: 1% by mass, heating mass reduction rate: 4% by mass)
Millex XLC-LL (trade name, manufactured by Mitsui Chemicals, Inc., phenol resin, hydroxyl group equivalent: 175, softening point: 77 ° C., water absorption: 1 mass%, heating mass reduction rate: 4 mass%)

(Inorganic filler)
SC2050-HLG (trade name, manufactured by Admatechs, silica filler dispersion, average particle size: 0.5 μm)
Aerosil R972 (trade name, manufactured by Nippon Aerosil Co., Ltd., silica, average particle size: 0.016 μm)

(Coupling agent)
NUC A-189 (trade name, manufactured by GE Toshiba Silicone Co., Ltd., γ-mercaptopropyltrimethoxysilane)
NUC A-1160 (trade name, manufactured by GE Toshiba Silicone Co., Ltd., γ-ureidopropyltriethoxysilane)

(Curing accelerator)
Cureazole 2PZ-CN (trade name, manufactured by Shikoku Kasei Co., Ltd., 1-cyanoethyl-2-phenylimidazole)

(High molecular weight component)
Acrylic rubber HTR-860P (trade name, manufactured by Teikoku Chemical Industry Co., Ltd., weight average molecular weight: 800,000, Tg: −7 ° C.)

  With the composition shown in Table 1, an epoxy resin and a phenol resin were mixed with a filler, and cyclohexanone was further added and stirred to obtain a uniform mixture. Subsequently, acrylic rubber is added to the mixture and stirred, and then a varnish-like resin composition is prepared by adding a coupling agent and a curing accelerator and stirring until uniform, and subsequently, using a 100 mesh filter. Filtered and vacuum degassed.

  The varnish-like resin composition thus prepared was applied onto a 38 μm-thick polyethylene terephthalate film (PET) that had been previously subjected to a release treatment. This is heated and dried in two stages of 90 ° C. (5 minutes) and then 140 ° C. (5 minutes) to form a B-stage coating film having a thickness of 20 μm. The prepared adhesive sheet was produced. Then, various characteristics were evaluated along the method shown below about each adhesive sheet produced in each Example.

[Measurement of shear viscosity]
The shear viscosity of the adhesive layer was evaluated by the following method.
After the support film was peeled off from the 8 adhesive sheets, 8 adhesive layers were bonded at 60 ° C. to obtain an adhesive sheet having a thickness of 160 μm.

  Next, the adhesive sheet was punched into a 10 mm square in the thickness direction. A circular aluminum plate jig having a diameter of 8 mm was set in ARES (manufactured by Rheometric Scientific), and the support film was peeled off from the punched adhesive sheet and set here. Thereafter, the shear viscosity was measured every 8 seconds while giving a strain of 5% under the condition of a heating rate of 5 ° C./min up to 35 to 140 ° C. The results are shown in Table 2.

[Confirmation of foaming at 200 ° C after heating at 140 degrees for 1 minute]
A sample as shown in FIG. 1 is obtained by first sandwiching an adhesive sheet punched into 10 mm square with an 18 mm square cover glass (thickness 0.15 mm) and laminating it on a hot plate at 60 ° C. so as not to enter air bubbles. Was made.

  This was the initial state, and the image was captured and saved with a scanner (resolution: 300 pix). Thereafter, the sample was heated at 140 ° C. for 1 minute using a hot plate, and the heated state was captured as an image with a scanner (resolution: 300 pix) and stored.

Next, the heated sample was heated at 200 ° C. using a hot plate, and the state after heating was similarly captured as an image with a scanner (resolution: 300 pix) and stored. The presence or absence of foaming was confirmed by comparing the state of the adhesive sheet before and after heating. The results are shown in Table 2.
The evaluation criteria are as follows.
No foaming: Void ratio is less than 5 area%.
With foaming: Void ratio is 5 area% or more.

[Measurement of die shear strength before sealing]
The adhesive strength was evaluated by measuring the die shear strength of the adhesive sheet according to the following procedure. First, the adhesive sheet was attached to a 400 μm thick wafer at 60 ° C. and diced to 5.0 mm square.

  The chip with the adhesive sheet separated into pieces is pressure-bonded to the surface of the chip treated with SiN under conditions of 140 ° C./100 gf / 1 second, and then a sample is prepared, and then 140 ° C./1 minute, and subsequently 200 ° C./1. Heat on a hot plate for minutes. The die shear strength was measured at 180 ° C. using the obtained test piece. The results are shown in Table 2.

[Shear storage modulus after heating at 200 ° C. for 5 minutes]
The shear storage modulus of the adhesive layer was evaluated by the following method.
After the support film was peeled off from the 8 adhesive sheets, 8 adhesive layers were bonded at 60 ° C. to obtain an adhesive sheet having a thickness of 160 μm.

  Next, the adhesive sheet was punched into a 10 mm square in the thickness direction. A circular aluminum plate jig having a diameter of 8 mm was set in ARES (manufactured by Rheometric Scientific), and the support film was peeled off from the punched adhesive sheet and set here. Thereafter, the shear storage modulus was measured every 200 seconds while applying a strain of 5% at 200 ° C., and the measured value after 5 minutes was recorded. The results are shown in Table 2.

[Evaluation of embedding and reflow resistance during sealing]
The reflow resistance of the adhesive layer was evaluated by the following method. First, 20 μm of the adhesive layer of the adhesive sheet was attached to a semiconductor wafer having a thickness of 75 μm at 60 ° C. Thereafter, they were diced to 7.5 mm square to obtain chips. The adhesive layer of the separated chip is pressure-bonded on a substrate surface coated with a resist (trade name: “AUS308”, manufactured by Taiyo Ink Manufacturing Co., Ltd.) under conditions of 140 ° C., 0.04 MPa, 1 second. Got.

  Next, the obtained sample was heated at 140 ° C. for 1 minute, and a thermal history equivalent to wire bonding (200 ° C., 5 minutes) was given to the sample using a hot plate. Next, sealing is performed under conditions of 180 ° C./13 MPa / 90 seconds using a mold sealing material (manufactured by Hitachi Chemical Co., Ltd., trade name: “CEL-9700HF”), followed by 175 ° C. for 5 hours. The package was obtained by heating.

A part of the obtained package was analyzed by SAT, and embeddability at the time of sealing was confirmed. The presence or absence of the sealing material was confirmed by observing the package cross section. The evaluation criteria for embeddability are as follows.
○: The void ratio is less than 15 area%.
X: The ratio of a void is 15 area% or more.

Further, the obtained package was exposed to the environment defined by JEDEC (level 2, 85 ° C., 60 RH%, 168 hours) to absorb moisture. Subsequently, the package after moisture absorption was passed through an IR reflow furnace (260 ° C., maximum temperature 265 ° C.) three times.
A case where no breakage of the package, a change in thickness, peeling of the interface, or the like was observed was evaluated as “A”, and a case where even one was observed was evaluated as “B”. The results are shown in Table 2.

[Measurement of die shear strength after curing]
The adhesive strength was evaluated by measuring the die shear strength of the adhesive sheet according to the following procedure. First, the adhesive sheet was attached to a 400 μm thick wafer at 60 ° C. and diced to 5.0 mm square. The chip with the adhesive sheet separated into pieces was pressure-bonded to the surface of the chip surface-treated with SiN under conditions of 140 ° C./100 gf / 1 second to prepare a sample.

  Then, it was heated on a hot plate at 140 ° C./1 minute, followed by 200 ° C./1 minute. The obtained sample was pressure-bonded at 180 ° C./13 MPa / 30 s as pressure bonding corresponding to the sealing conditions, and further heated at 170 ° C. for 3 hours to cure the adhesive sheet.

  The obtained sample was allowed to stand for 168 hours under the condition of 85 ° C./60 RH%, and then the die shear strength was immediately measured at 250 ° C., and this was taken as the adhesive strength. The results are shown in Table 2.

  As shown in Table 2, it is clear that the adhesive sheets (Examples 1 and 2) of the present invention are superior in filling property of unfilled parts by melting as compared with the adhesive sheets of Comparative Examples 1 and 2. It is.

Claims (6)

  An adhesive sheet composed of a resin composition, which does not foam at 200 ° C. or lower when heated at 140 ° C. for 1 minute, and is coated with SiN by heating at 140 ° C. for 1 minute and subsequently at 200 ° C. for 1 minute. An adhesive sheet having improved adhesion to the Si substrate and an adhesion measured at 180 ° C. of 1.0 MPa or more.   An adhesive sheet used in a method for producing a semiconductor element having a sealing step, which is composed of a resin composition and has a shear storage elastic modulus of 1 to 10 MPa at 200 ° C. after heating at 200 ° C. for 5 minutes, An adhesive sheet that can be completely adhered to an adherend by sealing a semiconductor element under conditions of 180 ° C./13 MPa / 90 seconds after heating at 140 ° C. for 1 minute and then at 200 ° C. for 5 minutes. The resin composition contains 100 parts by mass of a thermosetting resin, a crosslinkable functional group, a high molecular weight component having a weight average molecular weight of 100 to 800,000 and a Tg of −50 to 50 ° C. ~ 200 parts by mass, 50 to 150 parts by mass of an inorganic filler having an average particle size of 1.0 μm or less, and 0.20 to 0.80 parts by mass of a curing accelerator,
The adhesive sheet according to claim 1 or 2, wherein the thermosetting resin contains 15 to 50% by mass of a bifunctional epoxy resin that becomes liquid or softens at 70 ° C.   The inorganic filler having an average particle diameter of 1.0 μm or less is a first inorganic filler in which 99% by mass or more is distributed in a range of 0.1 to 4.0 μm, and 99% by mass or more is 0.01 to 1. The adhesive sheet according to claim 1, comprising a second inorganic filler distributed in 0 μm.   2. The adhesive sheet according to claim 1, wherein the adhesive force to the Si substrate coated with SiN is 2.0 MPa or more and the thickness is 5 to 250 μm.   The adhesive sheet according to any one of claims 1 to 5 is used, a chip is mounted at 140 ° C / 0.04 MPa / 1 second, and 140 ° C is applied in a preheating step after after-bonding or wire bonding. A semiconductor element manufactured by a sealing process of 180 ° C./13 MPa / 90 s through a wire bonding process at 200 ° C. or less and 5 minutes or less after adding a heat history of minutes.

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