KR20110010601A - Multilayer uv-curable adhesive film - Google Patents

Abstract

The present invention provides a composition comprising: (a) an upper layer that is substantially UV curable and has a glass transition temperature of 50 ° C. or less; And (b) an underlayer that is substantially not UV-curable. Additional embodiments include bundle wafer stack films, semiconductor wafers with attached multilayer adhesive films, processes for attaching semiconductor dies to a substrate, and methods of preventing individual diced dies from sticking together. .

Description

Multi-layer heat-curable adhesive film {MULTILAYER UV-CURABLE ADHESIVE FILM}

The present invention relates to a multilayer adhesive film for use in a semiconductor package, a method of using the film, and a semiconductor package assembled into the film. The film of the present invention, when used in a bundled wafer backside lamination process, does not allow individual dies to stick together after dicing.

Adhesive films are often used for the integration of semiconductor packages, for example in attaching silicon semiconductor dies to a substrate. Generally, the film is applied to a carrier and then B-staged to partially cure or dry the composition into a film form. The film can then be applied to the dicing tape, removing the carrier and applying the exposed side of the film to the back side of the semiconductor wafer, thereby sandwiching the adhesive film between the back side of the wafer and the dicing tape. This allows the wafer to be diced into individual dies to which an adhesive film is attached, and the combination of film and die comprising a multilayer film is hereinafter referred to as die structure. The die structure is then picked up from the dicing tape and left on the substrate together with the adhesive film near the substrate. The adhesive film, upon curing, generally uses heat application to bond the die to the substrate. Due to operational considerations, a time delay may be required between dicing the wafer into individual dies and picking up the die for bonding to the substrate. In this case, it has been found that the adhesive film on the back side of an individual die often sticks to the adhesive film on the back side of the adjacent die, causing one or more die to be removed from the carrier or dicing tape. This is a problem and it is desirable to obtain an adhesive film that does not cause the dies to stick together after dicing and before die attach.

 It is desirable to obtain an adhesive film that does not cause the dies to stick together after dicing and before die attach.

The present invention provides a composition comprising: (a) an upper layer that is substantially UV curable and has a glass transition temperature of 50 ° C. or less; And (b) an underlayer that is substantially not UV-curable.

In another embodiment, the present invention provides an adhesive film laminated on a support tape, wherein the adhesive film comprises: (a) an upper layer that is substantially UV curable and has a glass transition temperature of 50 ° C. or lower; And (b) a lower layer that is not substantially UV-curable.

In a further embodiment, the invention is a semiconductor wafer bonded to an adhesive film, wherein the adhesive film is (a) an upper layer bonded to the semiconductor wafer, substantially UV curable, and having a glass transition temperature of 50 ° C. or less; And (b) a lower layer that is not substantially UV-curable.

In another embodiment, the present invention is a process for attaching a semiconductor die to a substrate, comprising:

1. (a) an upper layer that is substantially UV curable and has a glass transition temperature of 50 ° C. or less; And (b) providing an adhesive film comprising an underlayer that is not substantially UV-curable;

2. providing a support tape having a back side and an adhesive side;

3. attaching the adhesive film to the supporting tape by contacting the lower layer of the adhesive film with the adhesive side of the supporting tape, thereby exposing the upper layer of the adhesive film, thereby forming a bundled wafer backside laminated film;

4. providing a semiconductor wafer having an active side and an inactive side;

5. attaching the bundled wafer backside laminated film to the semiconductor wafer by contacting the top layer of the adhesive film with the inactive side of the semiconductor wafer;

6. advancing the upper layer;

7. Dicing the semiconductor wafer and the attached multilayer adhesive film into several individual die structures;

8. picking up the selected individual die structure;

9. providing a substrate;

10. placing the selected individual die structures on the substrate such that the adhesive film is disposed between the back side of the die and the substrate; And

11. Attaching the individual die structures to the substrate using heat.

In another embodiment, the present invention is a method for preventing the individually diced dies from sticking together. The method comprises the following steps:

1. (a) an upper layer that is substantially UV curable and has a glass transition temperature of 50 ° C. or less; And (b) providing an adhesive film comprising an underlayer that is not substantially UV-curable;

2. providing a support tape having a back side and an adhesive side;

3. attaching the adhesive film to the support tape by contacting the lower layer of the adhesive film with the adhesive side of the support tape, thereby exposing the top layer of the adhesive film, thereby forming a bundled wafer backside laminated film;

4. providing a semiconductor wafer having an active side and an inactive side;

5. attaching the bundled wafer backside laminated film to the semiconductor wafer by bringing the upper layer of the adhesive film into contact with the inactive side of the semiconductor wafer;

6. advancing the upper layer;

7. Dicing the semiconductor wafer and the attached multilayer adhesive film into several individual die structures; And

8. Picking up the selected individual die structure.

Brief description of the drawings

The invention may be more fully understood by reading the following detailed description of the invention, with reference to the accompanying drawings in which:

1 is a cross-sectional view of a multilayer film of the present invention;

2 is a cross-sectional view of a semiconductor wafer to which the multilayer adhesive film of the present invention is attached;

3 is a cross-sectional view of the bundled wafer laminate film of the present invention;

4 is a cross-sectional view of a semiconductor wafer to which the bundled wafer laminate film of the present invention is attached;

5 is a cross-sectional view of a wafer diced into individual die structures in accordance with the present invention;

6 is a cross-sectional view of a semiconductor die attached to a substrate in accordance with the present invention;

7 prior art illustrates a cross-sectional view of reattachment problems experienced with prior art adhesive films.

Justice

The term "alkyl" refers to a branched or unbranched saturated hydrocarbon group of 1 to 24 carbon atoms, such as methyl ("Me"), ethyl ("Et"), n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, octyl, decyl and the like.

The term "advancing" means cure or partial cure.

The term "effective amount" of a compound, product, or composition means an amount of the compound, product, or composition sufficient to provide the desired result. The exact amount required will vary from package to package depending on the particular compound, product or composition used, the mode of administration thereof and the like. Thus, it is not always possible to specify the exact amount; Effective amounts can only be determined by one skilled in the art using routine experimentation.

The term “suitable” refers to moieties that are compatible with the compounds, products, or compositions provided herein for the purposes described. Suitability for the stated purpose can only be determined by one skilled in the art using routine experimentation.

The term “substituted” generally refers to carbon or a suitable heteroatom having a hydrogen atom or other atom that is removed and replaced by another moiety. Moreover, "substituted" is intended to refer to substituents that do not alter the basic and novel usefulness of the corresponding compounds, products or compositions of the invention.

The term “B-staging” (and utility thereof) refers to evaporating the solvent in the presence or absence of partial cure of the material or dissolving the material when the material is dissolved or dispersed in the solvent. When used purely without, it is used to refer to the processing of a material by heat or irradiation to partially cure the material in a sticky or more cured state. If the material is a flowable adhesive, B-stageization can provide extremely low flow without complete curing, allowing additional curing to be performed after using the adhesive to bond one molding to the other. Fluidity reduction can be achieved by partial evaporation or curing of the solvent, evaporation of the resin or polymer, or both.

The term “curing agent” is used to refer to any material or combination of materials that initiates, propagates or accelerates the curing of a composition, including but not limited to accelerators, catalysts, initiators and curing agents.

The term “UV-curable” is used to refer to any resin that is polymerized and / or crosslinked by the application of ultraviolet radiation.

The term "Tg" or "glass transition temperature" is used to refer to the temperature at which there is a material transition from the glassy state to the rubbery state.

Detailed description of the invention

The invention will be described in more detail with reference to the drawings illustrating various embodiments of the invention. The drawings are schematic and show features of the invention and its relevance to other features and structures and are not to scale. In order to improve the clarity of what is presented, the elements corresponding to the elements shown in the other figures, although all of them are easily distinguished in all the figures, have not been shown again in particular.

In one embodiment, the invention is a multilayer adhesive film. The film has at least an upper layer and a lower layer. 1 is a cross-sectional view of one embodiment of a film of the present invention having only an upper layer and a lower layer.

Optionally, if it is necessary to give the adhesive film additional desired performance, there may be additional layers (not shown) between the upper and lower layers. The glass transition temperature of the upper layer is 50 degrees C or less, and is substantially UV curable. The bottom layer is substantially non UV-curable.

2 shows a cross-sectional view of one embodiment of the present invention wherein the above-mentioned multilayer adhesive film is attached to the back side of the semiconductor wafer. The semiconductor wafer has a back side on the active side and on the opposite side of the active side. In the embodiment described in FIG. 2, a multilayer adhesive film is applied to a semiconductor wafer such that the top layer of the film is in direct contact with the backside side of the semiconductor wafer. In another embodiment (not shown), the multilayer adhesive film is applied to the front side or active side of the semiconductor wafer.

In another embodiment, the present invention is the multilayer adhesive film described above laminated on a support tape. In one embodiment of this embodiment, a bundled wafer stack (BWL) film is described in FIG. 3. In this embodiment, the support tape is a dicing tape and the multilayer adhesive film described above is attached to the dicing tape such that the lower layer of the film is in direct contact with the adhesive side of the dicing tape. The BWL film may then be attached to the semiconductor wafer to form another embodiment of the present invention described in FIG. 4. In this embodiment, the multilayer adhesive film is sandwiched between the semiconductor wafer and the dicing tape such that the upper layer of the film contacts the inactive side or the back side of the semiconductor wafer, or the lower layer of the film contacts the dicing tape. . In this embodiment, the BWL film may be referred to as a bundled wafer backside lamination (BWBL) film. In another embodiment (not shown), the multilayer adhesive film is sandwiched between the semiconductor wafer and the dicing tape so that the top layer of the film abuts the active side of the semiconductor wafer and the bottom layer of the film abuts the dicing tape.

Another embodiment of the invention is a process for attaching a semiconductor die to a substrate. First, a BWBL film is formed by attaching a multilayer adhesive film to a dicing tape as described above. The BWBL film is then attached to the semiconductor wafer so that the upper layer of the film is in direct contact with the backside side of the wafer. The upper layer of the multilayer adhesive film is then advanced through the application of ultraviolet radiation. Advancement of the upper layer may involve partial or complete cure as long as the amount of cure to prevent adhesion of the die during die pickup is sufficient. The semiconductor wafer is then diced, with the multilayer adhesive film attached thereto, to form several individual die structures as shown in FIG. 5. The selected individual die structures are then picked up and left on the substrate so that the adhesive film is impregnated between the die and the substrate. Finally, the die is attached to the substrate by applying heat to cure the underlayer of the multilayer adhesive film. 6 shows a cross-sectional view of a die attached to a substrate using the above process.

The glass transition temperature (Tg) of the upper layer of the multilayer adhesive film is 50 ° C. or less, and is substantially UV-curable. In one embodiment, the top layer contains (i) a UV-curable resin and (ii) a photoinitiator. Tg is measured after the film is formed (ie, after the composition has been B-staged or dried to form a film) and before UV curing of the film. Low Tg causes the film to flow sufficiently for adhesion to the semiconductor wafer at relatively low temperatures. In one embodiment, the Tg of the upper layer is less than 20 ° C. In another embodiment, the Tg of the upper layer is 0-20 ° C. UV-curable resins and photoinitiators allow the top layer to advance after attachment to the semiconductor wafer, thereby preventing the sticking of the adjacent die after dicing. Films are generally applied to semiconductor wafers using thermal processes such as lamination. It is generally desirable to have a lamination temperature of less than 80 ° C., and sometimes less than 65 ° C. is required. Low lamination temperatures are necessary for two reasons. First, lamination at high temperatures tends to advance (partially cure) the resin in the adhesive film. This can limit the working life of the film, which can also impede flow, which in turn can interfere with the bonding of the die to the substrate. Secondly, stacking at higher temperatures can distort the semiconductor wafer. This is particularly problematic as the semiconductor industry seeks thinner wafers, and inherently further encourages warping. Unfortunately, the low Tg of the top layer, which causes it to stack at low temperatures, can also cause the film to flow weakly at room temperature. Thus, after the film is laminated to the wafer and diced into individual dies, if the dies are not immediately picked up and placed on the substrate, the adhesive films on the adjacent dies tend to flow sufficiently to come into contact with each other. Since the resin used in the upper layer is often sticky to facilitate lamination to the wafer, the flow can cause the dies to stick together or "re-bond". This problem is illustrated in FIG. 7, which shows a prior art adhesive film that flows after dicing to induce re-adhesion. In the present invention, the UV-curable resin and the photoinitiator are requirements for allowing the upper layer of the film to be substantially advanced or cured after laminating the film to the wafer. This increases the molecular weight, thereby raising the melt viscosity of the upper layer, which helps to prevent the flow of the adhesive at ambient conditions, such as would be experienced during storage. This alleviates the sticking or re-adhesion problem.

The UV curable resin in the upper layer of the multilayer adhesive film can be any that can be reacted, advanced, crosslinked or polymerized in the presence of ultraviolet light. Even if any UV curable resin is used, non-limiting examples of suitable UV curable resins include maleimide, acrylate, vinyl ether and styrene. The UV curable resin is generally present in an effective amount of 5-100% by weight of the top layer composition, excluding the filler content.

In one embodiment, the UV curable resin is a solid aromatic bismaleimide (BMI) resin. Suitable solid BMI resins have the following general structure:

Wherein X is an aromatic group; Exemplary aromatic groups include the following:

Wherein n is 1 to 3;

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And

Bismaleimide resins having the X crosslinking groups are commercially available and can be obtained, for example, from Sartomer (USA) or HOS-Technic GmbH (Austria).

In another embodiment, the UV-curable resin is a maleimide resin having the following general structure:

Wherein n is 1 to 3 and X ¹ is an aliphatic or aromatic group. Example X ¹ moiety includes poly (butadiene), poly (carbonate), poly (urethane), poly (ether), poly (ester), simple hydrocarbons, and functional groups such as carbonyl, carboxyl, amide, carba Simple hydrocarbons including mate, urea or ethers are included. Resins of this type are commercially available and are available, for example, from National Starch and Chemical Company and Dainippon Ink and Chemical, Inc. It is available from.

In one embodiment, the UV-curable resin is a phenol novolac polyamide:

In another embodiment, the UV-curable resin is a 3-maleimidopropionic acid / dimethyloctanol adduct.

In further embodiments, the UV-curable resin is a maleimide resin selected from the group consisting of:

Wherein C ₃₆ is a linear or branched chain of 36 carbon atoms (with or without cyclic moiety).

In one embodiment, the UV-curable resin is a maleimide 2,5-furandione reaction product with aniline-1,4-bis (chloromethyl) benzene polymer.

Examples of suitable acrylate resins include those having the following general structure:

Wherein n is 1 to 6, R ¹ is —H or —CH ₃ and X ² is an aromatic or aliphatic group. Example X ² moieties include, but are not limited to, poly (butadiene), poly (carbonate), poly (urethane), poly (ether), poly (ester), simple hydrocarbons, and functional groups such as carbonyl, carboxyl Simple hydrocarbons, including amides, carbamates, ureas, or ethers. Commercially available materials include butyl (meth) acrylate, isobutyl (meth) acrylate, tricyclodecanedimethanol diacrylate, 2-ethylhexyl (meth) acrylate, available from Kyoeisha Chemical Co., LTD. , Isodecyl (meth) acrylate, n-lauryl (meth) acrylate, alkyl (meth) acrylate, tridecyl (meth) acrylate, n-stearyl (meth) acrylate, cyclohexyl (meth)- Acrylate, tetrahydrofurfuryl (meth) acrylate, 2-phenoxy ethyl (meth) acrylate, isobornyl (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexane Diol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, perfluorooctytetyl- (meth) acrylate, 1,10-decanediol di (meth) acrylate, nonylphenol polyphenol Polypropoxylate (meth) acrylate, and Polypentoxylate tetrahydrofurfuryl acrylate; Polybutadiene urethane dimethacrylate (CN302, NTX6513) and polybutadiene dimethacrylate (CN301, NTX6039, PRO6270), available from Sartomer Company, Inc; Polycarbonate urethane diacrylate (ArtResin UN9200A) available from Negami Chemical Industries Co., LTD; Acrylated aliphatic urethane oligomers (Ebecryl 230, 264, 265, 270, 284, 4830, 4833, 4834, 4835, 4866, 4881, 4883, 8402, 8800-20R, 8803, 8804) available from Radcure Specialties, Inc; Radcure Speciafities, Inc. Polyester acrylate oligomers available from Ebecryl 657, 770, 810, 830, 1657, 1810, 1830; And Sartomer Company, Inc. Epoxy acrylate resins (CN104, 111, 112, 115, 116, 117, 118, 119, 120, 124, 136) available from. In one embodiment, the acrylate resin is isobornyl acrylate, isobornyl methacrylate, lauryl acrylate, lauryl methacrylate, acrylate functional poly (butadiene) and methacrylate functionalities. Selected from the group consisting of poly (butadiene).

In one embodiment, the UV curable resin has isobornyl acrylate, isobornyl methacrylate, lauryl acrylate, lauryl methacrylate, acrylate functional poly (butadiene) and methacrylate functionalities. Selected from the group consisting of poly (butadiene).

Examples of suitable vinyl ether resins include those having the following general structure:

Wherein n is 1 to 6 and X ³ is an aromatic or aliphatic group. Example X ³ moieties include, but are not limited to, poly (butadiene), poly (carbonate), poly (urethane), poly (ether), poly (ester), simple hydrocarbons, and functional groups such as carbonyl, carboxyl Simple hydrocarbons, including carbamate, urea or ethers. Commercially available vinyl ether resins include cyclohenan- dimethanol divinyl ether; Dodecyl vinyl ether; Cyclohexyl vinyl ether; 2-ethylhexyl vinyl ether; Dipropylene glycol divinyl ether; Hexanediol divinyl ether; Octadecyl vinyl ether; Butanediol divinyl ether; Butanediol divinylether available from International Specialty Products (ISP); Sigma-Aldrich, Inc. Vectomer 4010, 4020, 4030, 4040, 4051, 4210, 4220, 4230, 4060, and 5015 available from.

Suitable styrene resins include resins having the following general structure:

Wherein n is at least 1, R ⁴ is —H or —CH ₃ , and X ⁶ is an aliphatic group. Examples of the X ⁶ moiety include poly (butadiene), poly (carbonate), poly (urethane), poly (ether), poly (ester), simple hydrocarbons, and functional groups such as carbonyl, carboxyl, carbamate Simple hydrocarbons, including urea or ethers. Such resins are commercially available and are available, for example, from National Starch and Chemical Company or Sigma-Aldrich Co. Available from.

The photoinitiator in the upper layer of the multilayer adhesive film may be any that initiates, promotes or advances the curing of the UV curable resin upon exposure to UV radiation. The photoinitiator is present in an effective amount, generally 0.1-10% by weight, of the composition of the upper layer, excluding the solvent content, before B-staging. Suitable photoinitiators include, but are not limited to, the following: 1-hydroxycyclohexyl-phenyl ketone, 2-benzyl-2- (dimethylamino) -1- [4- (available from Ciba Specialty Chemicals. 4-morpholinyl) phenyl] -1-butanone, 2-methyl-1- [4- (methylthio) phenyl] -2- (4-morpholinyl) -1-propanone, (2,2- Dimethoxy-1,2-diphenyl-ethan-1-one), 2-hydroxy-2-methoxy-1-phenyl-propane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2 -Hydroxy-2-methyl-1-phenyl-1-propanone, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphineoxide, 1-hydroxycyclohexyl-phenyl -Ketones, and 1- [4- {2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methoxy-1-propan-1-one, and blends thereof; Sartomer Company Ltd. Benzoin normal butyl ether, ethyl 4- (dimethylamino) benzoate, isopropyl thioxanthone, benzyl dimethyl ketal, oligo (2-hydroxy-2-methyl-1-4 (1-methyl-vinyl) ) Phenyl propane, 2-hydroxy-2-methyl-1-phenyl-1-propane, 2-hydroxy-2-methyl-1-phenyl propane, and mixtures thereof.

In addition to the one or more UV-curable resins, the top layer may comprise one or more additional resins that are not substantially UV-curable, ie that are not substantially advanced, crosslinked or polymerized upon exposure to ultraviolet light. Any additional resin in the top layer is generally present in an effective amount that is 5 to 95% by weight of the top layer composition, excluding the filler content. The amount and type of additional resin should be chosen so as not to interfere with the ability of the upper layer to stick to it when advancing with UV irradiation.

The top layer of the multilayer adhesive film can be any thickness needed for a particular semiconductor package and is generally 5 to 60 μm. In one embodiment, the top layer is 5-30 μm thick. The upper layer can be the same thickness as the lower layer or can be a different thickness.

The upper layer of film is substantially cured upon exposure to UV radiation after adhesion to the wafer; In contrast, the underlayer does not substantially cure upon exposure to UV radiation. This allows the resin to flow and wet out the rough surface of most substrates present in the underlying layer and then to cure upon heat application during die attachment. Thus, the multilayer adhesive film can bond the die to the substrate through pick-up and post-set heat curing operations. The underlying Tg can be anything that provides the desired flow and the desired wet-out during die attach. In one embodiment, the Tg of the lower layer is -30 ° C to 90 ° C. In another embodiment, the Tg of the lower layer is 0 ° C to 20 ° C. If the Tg of the lower layer is less than room temperature, the resin containing the lower layer will not be tacky. In that way, when the lower layers of the adhesive film on the proximal die come into contact with each other, they will not stick to each other, which will prevent sticking or reattaching. In contrast to the resin of the upper layer, any resin used in the lower layer is generally not tacky because it is not a requirement for strong adhesion to the dicing tape.

In one embodiment, the underlayer of the multilayer adhesive film comprises one or more resins that are not substantially UV-curable, ie they are not substantially forward, crosslinkable or polymerizable upon exposure to ultraviolet light.

In another embodiment, the underlayer of the multilayer adhesive film contains at least one resin that is UV-curable in the presence of a photoinitiator. In this embodiment, the photoinitiator is not present in the underlayer, so that the underlayer is not UV-curable and does not substantially advance or cure upon exposure to UV light. If the underlayer contains one or more UV-curable resins (without UV-photoinitiator), it is preferred not to use an adhesive film with the UV-curable dicing tape, which means that contact with the initiator in the dicing tape This is because when exposed to UV irradiation, curing can be initiated in the lower layer of the adhesive film, adhered too strongly to the dicing tape and potentially cause die picking problems.

The lower layer may contain only one resin or may contain a combination of several resins. Any resin used may be solid or liquid at room temperature, and when more than one resin is used, they may be any combination of liquid and solid. In one embodiment, the underlayer contains one or more epoxy resins.

The underlayer can be any thickness required for the specific semiconductor package and is generally 20 to 150 μm thick. The lower layer can be the same thickness as the upper layer or can be a different thickness.

Examples of resins that are not substantially UV-curable and suitable for encapsulation into the upper or lower layers of the adhesive film include epoxy, polyester, poly (butadiene), polyimide, benzocyclobutene, silicone olefins, silicone resins, cyanates Ester resins, thermosetting rubbers, polyolefins, siloxanes or diphenyloxide oligomers.

Suitable epoxy resins include bisphenols, naphthalenes and aliphatic type epoxides. Commercially available materials include Dainippon Ink & Chemicals, Inc. Bisphenol type epoxy resins available from Epiclon 830LVP, 830CRP, 835LV, 850CRP; Dainippon Ink & Chemicals, Inc. Naphthalene type epoxy (Epiclon HP4032) available from; Aliphatic epoxy resins available from Ciba Specialty Chemicals (Araldite CY179, 184, 192, 175, 179), those available from Union Carbide Corporation (Epoxy 1234, 249, 206), and Daicel Chemical Industries, Ltd. Available from EHPE-3150. Other suitable epoxy resins include alicyclic epoxy resins, bisphenol-A type epoxy resins, bisphenol-F type epoxy resins, epoxy novolac resins, biphenyl type epoxy resins, naphthalene type epoxy resins, dicyclopentadiene-phenol type epoxy resins, Cresol novolac epoxy resins, reactive epoxy diluents, and mixtures thereof. In one embodiment, the epoxy resin is a multifunctional epoxy resin derived from polyaddition compounds of dicyclopentadiene and phenol. In one embodiment, the epoxy resin is a rubber modified epoxy.

Suitable siliconized olefin resins are obtained by selective siliconation of silicon with divinyl materials having the general structure:

Wherein n ₁ is 2 or more, n ₂ is 1 or more, and n ₁ > n ₂ . Such materials are commercially available and are available, for example, from the National Starch and Chemical Company.

Suitable silicone resins include reactive silicone resins having the structure:

Wherein n is 0 or any integer, X ⁴ and X ⁵ are hydrogen, methyl, amine, epoxy, carboxyl, hydroxy, acrylate, methacrylate, mercapto, phenol, or vinyl functional group, R ² and R ³ may be —H, —CH ₃ , vinyl, phenyl, or any hydrocarbon structure with two or more carbons. Commercially available materials include KF8012, KF8002, KF8003, KF-1001, X-22-3710, KF6001, X-22-164C, KF2001, X available from Shin-Etsu Silicone International Trading (Shanghai) Co., Ltd. -22-170DX, X-22-173DX, X-22-174DX X-22-176DX, KF-857, KF862, KF8001, X-22-3367, and X-22-3939A.

Suitable cyanate ester resins include those having the following general structure:

In formula, n is 1 or more, and X <^7> has a general structural formula which is a hydrocarbon group. Example X ⁷ moieties include bisphenol, phenol or cresol novolac, dicyclopentadiene, polybutadiene, polycarbonate, polyurethane, polyether, or polyester. Commercially available materials include the following: AroCy L-10, AroCy XU366, AroCy XU371, AroCy XU378, XU71787.02L, and XU 71787.07L available from Huntsman LLC; Primaset PT30, Primaset PT30 S75, Primaset PT60, Primaset PT60S, Primaset BADCY1 Primaset DA230S, Primaset MethylCy, and Primaset LECY available from Lonza Group Limited; Oakwood Products, Inc. 2-allylphenol cyanate ester, 4-methoxyphenol cyanate ester, 2,2-bis (4-cyanatophenol) -1,1,1,3,3,3-hexafluoropropane, available from Bisphenol A cyanate ester, diallyl bisphenol A cyanate ester, 4-phenylphenol cyanate ester, 1,1,1-tris (4-cyanatophenyl) ethane, 4-cumylphenol cyanate ester, 1,1- Bis (4-cyanatophenyl) ethane, 2,2,3,4,4,5,5,6,6,7,7-dodecafluorooctanediol dicyanate ester, and 4,4'-bisphenol Cyanate esters.

Examples of suitable thermoset rubbers include carboxy terminated butadiene-nitrile (CTBN) rubber, carboxy terminated butadiene-nitrile (CTBN) / epoxy adduct, acrylate rubber, vinyl-terminated butadiene rubber, and nitrile butadiene rubber (NBR) Included. In one embodiment, the CTBN epoxy adduct consists of about 20 to 80 wt% CTBN and about 20 to 80 wt% diglycidyl ether bisphenol A: bisphenol A epoxy (DGEBA). Various CTBN materials are available from Noveon Inc. Various bisphenol A epoxy materials are available from Dainippon Ink and Chemicals, Inc. And Shell Chemicals. NBR rubber is commercially available from Zeon Corporation.

Suitable poly (butadiene) polymers include poly (butadiene), epoxidized poly (butadiene), maleic poly (butadiene), acrylated poly (butadiene), butadiene-styrene copolymers, nitrile-butadiene rubber (NBR), and Butadiene-acrylonitrile copolymers such as carboxyl terminated butadiene-acrylonitrile (CTBN) rubbers. Commercially available materials include homopolymer butadiene (Ricon130, 131, 134, 142, 150, 152, 153, 154, 156, 157, P30D) available from Sartomer Company, Inc; Sartomer Company Inc. Random copolymers of butadiene and styrene available from (Ricon 100, 181, 184); Maleated poly (butadiene) available from Sartomer Company, Inc (Ricon 130MA8, 130MA13, 130MA20, 131MA5, 131MA10, 131MA17, 131 MA20, 156MA17); Acrylated poly (butadiene) available from Sartomer Company, Inc (CN302, NTX6513, CN301, NTX6039, PRO6270, Ricacryl 3100, Ricacryl 3500); Sartomer Company, Inc. Epoxidized Poly (Butadiene) (Polybd 600, 605) available from Daicel Chemical Industries, Ltd. Epolead PB3600 available from; And acrylonitrile and butadiene copolymers (Hycar CTBN series, ATBN series, VTBN series and ETBN series) available from Hanse Chemical.

In one embodiment, the upper layer of the multilayer adhesive film contains a rubber copolymer such as a copolymer of butadiene, acrylonitrile and acrylic acid (CTBN). Suitable rubber copolymers include, for example, NIPOL® 1072 available from Zeon Chemicals LP. The rubber copolymer aids in providing the low Tg and flexibility needed for lamination to the wafer.

The lower layer of the adhesive film contains a thermosetting agent. The upper layer of the adhesive film may optionally include a thermosetting agent when the thermosetting resin is included in its composition. The thermosetting resin may be the same as or different from the UV-curable resin in the upper layer. For example, the bismaleimide resin can be initiated by UV or thermal means. If bismaleimide resins are used in the presence of both photoinitiators and thermal initiators, they will originally cure (after lamination to semiconductor wafers) during UV exposure. However, some unsaturated bonds may still be present after the curing step. The inclusion of a thermal initiator in addition to the UV initiator allows for more complete curing of the resin upon application of heat downstream in the processor (generally during die attach curing). The presence of the thermal initiator in the underlayer allows the underlayer to harden upon heating and adhere to the substrate.

The thermal curing agent, except for the solvent content, is present in an effective amount of generally 10% by weight or less of the lower layer composition before B-staging. When used in the upper layer, the thermal curing agent, except for the solvent content, is generally present in an effective amount of up to 10% by weight of the upper layer composition before B-staging. Thermal curing agents can be ionic or free radicals, depending on the particular resin used in each layer. Examples of suitable ion curing agents include aromatic amines, cycloaliphatic amines, aliphatic amines, tertiary phosphines, triazines, metal salts, aromatic hydroxyl compounds, dicyandiamides, adipic acid dihydrazides, BF3-amine complexes, amines salt; Imidazoles such as 2-methylimidazole, 2-undecylimidazole, 2-heptadecyl imidazole, 2-phenylimidazole, 2-ethyl 4-methyl imidazole, 1-benzyl-2-methyl Midazole, 1-propyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl- Adducts of 2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-guanaminoethyl-2-methylimidazole, imidazole and trimellitic acid, and modified imidazole compound; Amines and tertiary amines such as N, N-dimethyl benzylamine, N, N-dimethylaniline, N, N-dimethyltoluidine, N, N-dimethyl-p-anisidine, p-halogeno-N, N-dimethyl Aniline, 2-N-ethylanilino ethanol, tri-p-butylamine, pyridine, quinoline, N-methylmorpholine, triethanolamine, triethylenediamine, N, N, N ', N'-tetramethylbutanediamine, N-methylpiperidine, and 4,4'-diamino diphenyl sulfone; Phenols such as phenol, cresol, xylenol, resorcin, and phloroglucin; Organometallic salts such as lead naphthenate, lead stearate, zinc naphthenate, zinc octolate, tin oleate, dibutyl tin maleate, manganese naphthenate, cobalt naphthenate, and acetyl acetone iron; Inorganic metal salts such as tin chloride, zinc chloride and aluminum chloride; Di-t-butyl diperphthalate; Acid hydrates such as carboxylic acid hydrate, maleic acid hydrate, phthalic acid hydrate, lauric acid hydrate, pyromellitic acid hydrate, hexahydro phthalic acid hydrate; Hexahydro pyromellitic acid hydrate and hexahydrotrimellitic acid hydrate. Examples of suitable free radical curing agents include peroxides and azo compounds such as benzoyl peroxide, lauroyl peroxide, tertiary butyl peroxide, octanoyl peroxide, acetyl peroxide, para-chlorobenzoyl peroxide, butyl perocto 8, dicumyl peroxide, azoisobutylonitrile, 2,2'-azobispropane, 2,2'-azobis (2-methyl-propanenitrile), 2,2'-azobis (2-methyl- Propanenitrile), 2,2'-azobis (2-methyl-butanenitrile), m, m'- azocystyrene and hydrozone.

The curing agent may also be one used for a curing accelerator such as an epoxy curing agent and may be triphenylphosphine, alkyl-substituted imidazole, imidazolium salt, onium salt, quaternary phosphonium compound, onium borate, metal chelate, And 1,8-diazacyclo [5.4.0] undex-7-ene.

Metal compounds may also be employed as hardeners or accelerators for cyanate ester resin systems, including but not limited to metal naphthenates, metal acetylacetonates (chelates), metal octoates, metal acetates, metals Halides, metal imidazole complexes and metal amine complexes may be included.

Any suitable method for producing a multilayer film can be employed. In one embodiment, the upper and lower layers are formed separately and then laminated together to form a multilayer adhesive film. Suitable lamination temperatures vary depending on the Tg of the specific film, with a general range of 50 to 100 ° C. Lamination pressure is generally 5 to 60 psi.

Practitioners may choose to include additional components on top or bottom of the multilayer adhesive film for the purpose of individualizing the film properties to suit a particular semiconductor package or manufacturing process. The components are of a type and amount known in the art including, but not limited to, fillers, coupling agents, adhesion promoters, surfactants, wetting agents, flow control agents, air release agents, tackifying resins, and solvents. .

One or more fillers may be included to adjust a number of properties including, but not limited to, rheology, stress, coefficient of thermal expansion, electrical and / or thermal conductivity, and modulus. No particular type of filler is important to the present invention and may be selected by those skilled in the art to suit the needs of a particular target application. The filler may be conductive or nonconductive. Non-limiting examples of suitable conductive fillers include carbon black, graphite, gold, silver, copper, platinum, palladium, nickel, aluminum, silicon carbide, boron nitride, diamond and alumina. Non-limiting examples of suitable nonconductive fillers include alumina, aluminum hydroxide, silica, vermiculite, mica, wollastonite, calcium carbonate, titania, sand, glass, barium sulfate, zirconium, carbon black, organic fillers and halogenated ethylene polymers such as Tetrafluoroethylene, trifluoroethylene, vinylidene fluoride, vinyl fluoride, vinylidene chloride, and vinyl chloride. The filler particles may be of any suitable size ranging from nano size to several mils. The choice of size for any particular package structure is at the discretion of the skilled person. The filler may be present in an amount ranging from 0 to 95% by weight of the film layer before B-staging, excluding the solvent content.

In one embodiment, the coupling agent or adhesion promoter may be included in the upper and / or lower layers of the multilayer adhesive film. Adhesion promoter selection will depend on the application requirements and the particular resin chemistry employed. Adhesion promoters, if used, will be used in an effective amount, generally 5% by weight or less of the film layer before B-staging, except for the solvent content. Examples of suitable adhesion promoters include the following: epoxy-type silane coupling agents, amine-type silane coupling agents, mercapto-type silane coupling agents; Gamma-methacryloxypropyltrimethoxysilane; Glycidoxypropyl trimethoxysilane; Z6040 epoxy silane, Z6030 methacryloxypropyltrimethoxysilane or Z6020 amine silane available from Dow Corning; A186 Silane, A187 Silane, A174 Silane, or A1289 available from OSI Silquest; Organosilane SI264 available from Degussa; Johoku Chemical CBT-1 carbobenzotriazole available from Johoku Chemical; Functional benzotriazoles; Thiazole; Titanate; And zirconate.

In further embodiments, surfactants may be added to the upper and / or lower layers of the multilayer adhesive film. Suitable surfactants include silicones, polyethylene glycols, polyoxyethylene / polyoxypropylene block copolymers, ethylene diamine based polyoxyethylene / polyoxypropylene block copolymers, polyol-based polyoxyalkylenes, fatty alcohol-based polyoxyalkyls Lene, fatty alcohol-based polyoxyalkylene alkyl ethers. If used, the surfactant will be used in an effective amount; Typical effective amounts are amounts of up to 5% by weight of the film layer before B-staging, excluding the solvent content.

In another embodiment, the wetting agent may be included in the upper and / or lower layers of the multilayer adhesive film. Wetting agent selection will depend on the application requirements and the specific resin chemistry used. Wetting agents, if used, are used in an effective amount: A typical effective amount is 5% by weight or less of the film layer before B-staging, excluding the solvent content. Examples of suitable humectants include Fluorad FC-4430 Fluorosurfactant, available from 3M, Clariant Fluowet OTN, BYK W-990, Surfynol 104 Surfactant, Crompton Sowet L-7280, Triton X100, preferably Mw 240 available from Rhom and Haas. More than propylene glycol, gamma-butyrolactone, rapeseed oil, glycerin or other fatty acids, and silanes.

In further embodiments, flow control agents may be included in the upper and / or lower layers of the multilayer adhesive film. Flow regulator screening will depend on the application requirements and the specific resin chemistry employed. The flow control agent, if used, will be present in an effective amount: The effective amount is up to 20% by weight of the film layer before B-staging, excluding the solvent content. Examples of suitable flow regulators include Cab-O-Sil TS720, available from Cabot, Aerosil R202 or R972, available from Degussa, fumed silica, fumed alumina or fumed metal oxides.

In further embodiments, an air release agent (antifoam) can be included in the upper and / or lower layers of the multilayer adhesive film. The air release agent selection will depend on the application requirements and the specific resin chemistry employed. Air release agents, if used, will be used in an effective amount. Typical effective amounts are 5% by weight or less of the film layer before B-staging, excluding solvent content. Examples of suitable air release agents include Antifoam 1400, DuPont Modoflow, and BYK A-510 available from Dow Corning.

In some embodiments, the upper and / or lower layers of the multilayer adhesive film are formulated with tackifying resins for adhesion improvement and tack introduction; Examples of tackifying resins include naturally occurring resins and modified naturally occurring resins; Polyterpene resins; Phenolic terpene resins; Coumarone-indene resin; Aliphatic and aromatic petroleum hydrocarbon resins; Phthalate esters; Hydrogenated hydrocarbons, hydrogenated rosin and hydrogenated rosin esters. Tackifying resin, when used, is used in an effective amount. A typical effective amount is 5% by weight or less of the film layer before B-staging, excluding the solvent content.

In some embodiments, other components, such as diluents such as liquid polybutene or polypropylene; Petroleum waxes such as paraffin and microcrystalline waxes, polyethylene greases, hydrogenated animals, fish and plant fats, mineral oils and synthetic waxes, naphthenic or paraffin mineral oils may be included in the upper and / or lower layers of the multilayer adhesive film. have.

Other additives of the type and amount known to those skilled in the art, such as stabilizers, antioxidants, impact modifiers, and colorants, may also be added to the upper and / or lower layers of the multilayer adhesive film.

Conventional solvents with suitable melting points in the range of 25 ° C. to 230 ° C. may be added to the upper and / or lower layers of the multilayer adhesive film. Examples of suitable solvents that may be used include ketones, esters, alcohols, ethers, and other conventional solvents that are stable and dissolve the curable resin in the composition. Suitable solvents include γ-butyrolactone, propylene glycol methyl ethyl acetate (PGMEA), methyl ethyl ketone (MEK), toluene, ethyl acetate, and 4-methyl-2-pentanone.

One or more void reduction compounds may also be added to the upper and / or lower layers of the multilayer adhesive film. Suitable gap reducing compounds include, but are not limited to, those having two or more Si—O bonds and one or more reactive functionalities in series with one another. Non-limiting examples of this type of gap reducing compound include the following:

(Methacryloxypropyltris (trimethylsiloxy) silane);

(비닐 말단처리 폴리디메틸실록산);

(Vinyl terminated polydimethylsiloxane);

(Vinyl terminated (15-17% diphenylsiloxane) -dimethylsiloxane copolymer);

(Epoxypropoxy propyl terminated polydimethylsiloxane);

((0.8-1.2% vinylmethylsiloxane) -dimethylsiloxane copolymer, trimethylsiloxy terminated);

(Methacryloxypropyl t-structure siloxane); And combinations thereof.

Each layer of the multilayer adhesive film is integrated in any suitable manner known in the art. The individual layers can be integrated in different ways or in the same manner as appropriate for the particular formulation and manufacturing environment employed. In one typical process, the film layer composition is coated on the carrier and forms a thin, uniform layer. The composition is then B-staged to produce a layer of non-tacky, uniform adhesive film. Curing of the adhesive film layer can be accomplished in a number of ways depending on the adhesive formulation employed.

In one embodiment, the upper and / or lower layer composition contains one or more liquid curable resins and a solvent. In this embodiment, the adhesive is cured to a non-tacky or very slow flow state by heating the composition sufficiently to evaporate the solvent and partially cure the curable resin or resins.

In another embodiment, the upper and / or lower layer composition contains a solid curable resin that is dissolved in a solvent. In this embodiment, the adhesive sufficiently heats the composition to evaporate the solvent and leaves a non-tacky resin-based film to cure to a non-tacky or very slow flow state. The method is particularly well suited to the upper layers of multilayer adhesive films, since the advancement of the resin is not necessary to produce a non-tacky film layer, since a UV-curable resin system can be used.

In another embodiment, the upper and / or lower layer composition contains one or more liquid, thermosetting resins. In this embodiment, the composition is cured to a non-tacky or very slow flow state by heating the adhesive sufficiently to partially advance the curable resin into a non-tacky or very slow flow state.

The carrier for the individual film layer or multilayer adhesive film can be any of which the individual layer composition can be applied to the thin layer and which will retain the composition during B-stage to the film. The carrier may also hold the film through application to the items to be bonded and / or additional processing steps, such as lamination to a wafer, another film layer or dicing tape. One particularly suitable carrier is a release liner. Examples of suitable release liners include polyimide (Pl) films, polyethylenenaphthalate (PEN) films, and polyethyleneterephthalate (PET) films.

In one embodiment of the present invention, the multilayer adhesive film described above is attached to the dicing tape such that the lower layer of the multilayer adhesive film is in direct contact with the dicing tape. The multilayer adhesive film is generally attached to the dicing tape through lamination. The dicing tape can be a pressure sensitive adhesive (PSA) dicing tape or an ultraviolet (UV) -curable dicing tape. Typical tapes have an adhesive thickness of 3 to 30 μm on polyolefin or polyvinyl chloride (PVC) carrier films that are 70 to 110 μm thick, but those skilled in the art can choose tapes with different structures to suit the particular industrial process to be used. Will be taken into account.

In another embodiment of the invention, the BWBL film described above is attached to the semiconductor wafer such that the multilayer adhesive film is sandwiched between the semiconductor wafer and the dicing tape. In this construction, the upper layer of the multilayer adhesive film is in contact with the back surface or inactive side of the semiconductor wafer, and the lower layer of the multilayer adhesive film is in contact with the adhesive side of the dicing tape. BWBL films are generally attached to a semiconductor wafer using a lamination process at a temperature of 40-100 ° C. and a pressure of 5-40 psi. In one embodiment, the film is laminated to the semiconductor wafer at a temperature of 50 to 80 ° C. and a pressure of 15 to 30 psi.

Another embodiment of the invention is a process for attaching a semiconductor die to a substrate. First, a BWBL film is formed using a multilayer adhesive film and dicing tape as described above. Subsequently, the BWBL film is attached to the semiconductor wafer such that the upper layer of the film is directly in contact with the backside or inactive side of the semiconductor wafer as described above. The UV curable resin in the upper layer is then advanced or substantially cured through the application of ultraviolet radiation. UV irradiation is applied to the back side of the semiconductor wafer to pass through the lower layer of the dicing tape and the multilayer adhesive film to initiate curing of the UV-curable resin in the upper layer of the multilayer adhesive film. UV radiation can be provided in any suitable manner and at a dosage for the particular manufacturing process employed. Typical UV radiation dosages range from 50 to 500 mJ / cm ² . In one embodiment, the UV radiation ranges from 100 to 300 mJ / cm ² . Subsequently, the semiconductor wafer is diced into a number of individual die structures along the multilayer adhesive film attached thereto. The die may be of any size and shape suitable for a particular end use, and the dicing may be performed using any known method in the art. The selected individual die structures are then picked up and left on the substrate so that the adhesive film is inserted between the back side of the die and the substrate. The "pickup and stationary" operation is generally performed using automated die attach equipment. Finally, the die is attached to the substrate by applying heat. Curing can be carried out at a temperature in the range from 90 to 180 ° C. within a time ranging from a few seconds to several hours. Curing can be carried out in one step or in several steps.

It is noted that in the process embodiments described above, UV curing is the focus for making the upper layer of the multilayer adhesive film avoid flowing at room temperature. This, in other words, prevents neighboring dies from sticking together after dicing when removing the individual dies from the dicing tape.

Example

Three exemplary multilayer adhesive films were prepared using the same lower film formulation with varying top formulations. The layer composition excluding the solvent is shown in Table 1 in detail.

Each layer was prepared by mixing all the components for 30 minutes using high shear mixing at about 5000 rpm until a homogeneous mixture was obtained. To the composition, 50-80% by weight methyl ethyl ketone (MEK) solvent was added to dissolve all solid resins and allow the mixture to be uniformly applied to the release liner. The mixture was degassed in a vacuum chamber to allow air bubbles to be released. The mixture was then coated on a silicone-coated release liner and dried at 100 ° C. for 3 minutes in a convection oven to form a film. After drying (B-stage) the mixture was applied in an amount sufficient to make the upper film about 20 μm thick and the lower film about 40 μm thick.

Samples of the upper film were tested using a flow meter to determine the melt viscosity before UV irradiation. The sample of the upper film was then exposed to 500 mJ / cm ² UV radiation and tested again for melt viscosity. The test results are shown in Table 2.

Samples of the upper film were laminated to the lower film using a roll laminator at 80 ° C. under 20 psi pressure to form a corresponding multilayer adhesive film. It should be noted that the upper film samples are not examined until they are laminated to the lower film to form a multilayer adhesive film test sample.

Multilayer adhesive films were tested for die shear strength, weight loss, peel strength, re-adhesion, and pickup performance. The specimens were laminated at a room temperature with a multilayer adhesive film selected on a dicing tape to form a die shear strength by forming a BWBL with a lower layer of the multilayer adhesive film and an upper layer of the exposed multilayer adhesive film against the dicing tape. Prepared for the exam. Subsequently, the BWBL film was laminated to a silicon wafer whose upper layer was in contact with the back side or inactive side of the wafer at 65 ° C. and 20 psi. The film on the back side of the wafer was then exposed to UV irradiation of 200 mJ / cm ² . The wafer was diced into individual die structures with a multilayer adhesive film attached. The individual die structures located on the larger silicon substrates were picked up and thermoset at 175 ° C. for 1 hour. Die shear strength was tested in a Dage die shear strength tester at room temperature and 260 ° C. Five specimens were tested for each sample and the arithmetic mean value was reported. In general, die shear strengths in excess of 1.0 kg _f / die are required when testing 100 × 100 mil dies at 260 ° C. It should be noted that 80 x 80 mil dies were employed for the purposes of this embodiment. Smaller dies are generally expected to provide lower shear strength readings with equivalent adhesives, so readings above 1.0 kg _f / die at 80 x 80 mil dies are considered to exceed typical requirements.

Weight loss at various temperatures was tested using a Perkin-Elmer thermogravimetric analyzer (TGA) at a ramp rate of 10 ° C./min. Loss of weight is generally tested on the adhesive film to ensure that there is no excessive outgassing that may cause voids and other performance problems in the final assembly. In general, weight loss of less than 0.8% is a requirement at 150 ° C.

Peeling strength evaluated by laminating | stacking a multilayer adhesive film on PSA dicing tape at room temperature so that the lower layer of a film might contact the adhesive agent (PSA) side of a dicing tape, and form a BWL film. A 1 inch wide specimen of BWL film was cut out. The BWL film sample was laminated to a silicon substrate (between the lower layer of the multilayer film and the substrate) using a double sided tape so that the dicing tape was exposed on the opposite side of the substrate. The dicing tape was then peeled off the multilayer adhesive film at an angle of 180 °. Peel strength is tested to prevent the adhesive film from sticking too hard to the dicing tape. Too high peel strength causes the adhesive film to delaminate from the semiconductor die, remaining on the dicing tape during die pickup. In general, a peel strength of less than 0.2 N / cm at room temperature is required.

Die reattachment and pickup removes the release liner from the underlayer of the multilayer adhesive film and causes it to be PSA at room temperature so that the underlayer of the multilayer adhesive film faces the adhesive (PSA) side of the dicing tape to form a BWBL film. It laminated | stacked on the dicing tape and evaluated. The release liner is then removed from the top layer of the BWBL film (top layer of the original multilayer adhesive film) and 55DC and 20 psi on the back or inactive side of the 100 μm thick silicon wafer, using the top layer of the BWBL film to the back side of the wafer. The BWBL film was laminated by pressure. The back side of the silicon wafer with attached BWBL was then exposed to 500 mJ / cm ² radiation to cure the UV-curable resin in the upper layer of the multilayer adhesive film. Subsequently, the wafer to which the BWBL was attached was diced into individual die structures with a multilayer adhesive film attached to its back side and which could start moving from the dicing tape of the BWBL film. Immediately after dicing, several individual die structures were manually picked up from the diced wafer, and it was noted whether any of the adjacent die structures were stuck to the picked up one. If any proximity die structure sticks to the picked-up, the sample is marked as reattached and the pickup is rated "poor". However, if the near die structure was not picked up at all, the sample was marked as reattached "none" and the pickup was rated "good". The diced wafer was then allowed to stand at room temperature for 3 hours and the pickup test procedure was repeated to determine whether the multilayer adhesive film would flow sufficiently within that time to cause reattachment problems. The test results of the multilayer adhesive film sample are shown in Table 3.

Many modifications and variations of the present invention are possible without departing from the spirit and scope thereof, as will be apparent to those skilled in the art. The specific embodiments described herein are provided by way of illustration only, and the invention is limited only by the claims, including the full scope of equivalents to which the appended claims are entitled.

Claims (20)

(a) an upper layer that is substantially UV curable and has a glass transition temperature of 50 ° C. or less; And (b) an underlayer that is substantially not UV-curable. The adhesive film according to claim 1, wherein the upper layer contains a UV curable resin selected from the group consisting of acrylates and bismaleimide. The adhesive film according to claim 1, wherein the lower layer contains an epoxy resin. The adhesive film of Claim 1 whose glass transition temperature of an upper layer is 0-20 degreeC. The adhesive film is (a) an upper layer that is substantially UV curable and has a glass transition temperature of 50 ° C. or lower; And (b) an underlayer that is substantially not UV-curable. The adhesive film according to claim 5, wherein the upper layer contains a UV curable resin selected from the group consisting of acrylates and bismaleimide. The adhesive film of Claim 5 in which an underlayer contains an epoxy resin. The adhesive film of claim 5 wherein the support tape is a dicing tape selected from the group consisting of PSA dicing tapes and UV-curable dicing tapes. The adhesive film is (a) an upper layer bonded to the semiconductor wafer, substantially UV curable, and having a glass transition temperature of 50 ° C. or lower; And (b) an underlayer that is substantially not UV-curable. 10. The semiconductor wafer according to claim 9, wherein the upper layer contains a UV curable resin selected from the group consisting of acrylates and bismaleimide. The semiconductor wafer according to claim 9, wherein the lower layer contains an epoxy resin. A process for attaching a semiconductor die to a substrate, comprising:
a. (a) an upper layer that is substantially UV curable and has a glass transition temperature of 50 ° C. or less; And (b) providing an adhesive film comprising an underlayer that is not substantially UV-curable;
b. Providing a support tape having a back side and an adhesive side;
c. Contacting the lower layer of the adhesive film and the adhesive side of the support tape to attach the adhesive film to the support tape, thereby exposing the upper layer of the adhesive film, thereby forming a bundled wafer backside laminated film;
d. Providing a semiconductor wafer having an active side and an inactive side;
e. Attaching the bundled wafer backside laminated film to the semiconductor wafer by contacting an upper layer of adhesive film contact with an inactive side of the semiconductor wafer;
f. Advancing the upper layer;
g. Dicing the semiconductor wafer and the attached multilayer adhesive film into several individual die structures;
h. Picking up the selected individual die structure;
i. Providing a substrate;
j. Placing the selected individual die structures on the substrate such that the adhesive film is disposed between the back side of the die and the substrate; And
k. Attaching the individual die structures to the substrate using heat. 13. The process of claim 12, wherein the top layer contains a UV curable resin selected from the group consisting of acrylates and bismaleimide. The process according to claim 12, wherein the lower layer contains an epoxy resin. 13. The process of claim 12 wherein the glass transition temperature of the upper layer is from 0 to 20 ° C. 13. The process of claim 12 wherein the support tape is a dicing tape selected from the group consisting of PSA dicing tapes and UV-curable dicing tapes. A method of preventing individual diced dies from sticking to each other, comprising the following steps:
a) (a) an upper layer that is substantially UV curable and has a glass transition temperature of 50 ° C. or less; And (b) providing an adhesive film comprising an underlayer that is not substantially UV-curable;
b) providing a support tape having a back side and an adhesive side;
c) attaching the adhesive film to the support tape by contacting the lower layer of the adhesive film with the adhesive side of the support tape, thereby exposing the top layer of the adhesive film, thereby forming a bundled wafer backside laminated film;
d) providing a semiconductor wafer having an active side and an inactive side;
e) attaching the bundled wafer backside laminated film to the semiconductor wafer by contacting the upper layer of the adhesive film with the inactive side of the semiconductor wafer;
f) advancing the upper layer;
g) dicing the semiconductor wafer and the attached multilayer adhesive film into several individual die structures; And
h) picking up the selected individual die structures. 18. The method of claim 17, wherein the top layer contains a UV curable resin selected from the group consisting of acrylates and bismaleimide. 18. The method of claim 17, wherein the lower layer contains an epoxy resin. 18. The method of claim 17, wherein the support tape is a dicing tape selected from the group consisting of pressure sensitive adhesive (PSA) dicing tapes and UV-curable dicing tapes.

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