Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor – Including adhesive bonding step
Reexamination Certificate
2002-11-20
2004-08-31
Tucker, Philip (Department: 1712)
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
Including adhesive bonding step
C428S414000, C428S446000, C428S448000, C428S473500, C428S500000, C428S521000, C428S523000
Reexamination Certificate
active
06784025
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to die attach adhesives and encapsulants containing silane and cross-linking functionalities for use in semiconductor packages, and to semiconductor packages in which the semiconductor is adhered to a substrate with the die attach adhesive.
BACKGROUND OF THE INVENTION
Adhesive compositions are used in many industries, such as the microelectronics industry, where good adhesion to metal and organic substrates and low viscosity for easy dispensability are important requisites.
Adhesion to metal and organic substrates is not always easily achievable, and the addition of silane adhesion promoters to adhesive formulations is one means of correcting this deficiency. Commonly used and commercially available silanes are small molecules that tend to volatilize significantly before the cure temperature of the adhesive is reached. Because silanes tend to be subject to hydrolysis, the addition of higher amounts of the silanes to offset the volatility could lead in turn to the presence of moisture in the adhesive compositions. This could be a problem in many applications. With reference to microelectronic devices, moisture creates the potential, through corrosion of circuits or voiding of the moisture and delamination of device packaging, for eventual failure of the device.
As a solution to these problems this specification discloses adhesion promoting resins with sufficient molecular weight to give lower volatility than the silanes currently commercially available. The adhesion promoting resins disclosed in this specification are curable compositions that are suitable for use as adhesives, encapsulants, or sealants, particularly for applications within the microelectronic industry.
SUMMARY OF THE INVENTION
This invention is a semiconductor package using a curable die attach adhesive and encapsulant formulation comprising a resin that contains an oligomeric or polymeric segment and a silane segment, a conductive or nonconductive filler, and optionally, an initiator. The silane segment on the resin will be present at the terminus of an oligomeric segment, or at a terminus or the termini of a polymeric segment, or at the terminus or termini and pendant from a polymeric segment.
DETAILED DESCRIPTION OF THE INVENTION
The oligomeric or polymeric segment of the resin used in the adhesive and encapsulant formulation will contain at least one carbon to carbon double bond, and can be provided by a precursor resin or compound that is commercially available. Alternatively, the precursor resin or compound can be synthesized by the practitioner.
Suitable oligomeric segment precursors are linear or branched hydrocarbons having 1 to 50 carbon atoms, which contain a reactive functionality, excluding epoxy, for ultimate reaction with a co-reactive functionality, excluding epoxy, on the silane segment precursor. Exemplary precursors include N-methylallylamine, N-ethyl-2-methylallyl-amine, diallylamine, N,N′-diethyl-2-butene-1,4-diamine, N-allylcyclopentyl-amine, allylcyclohexylamine, 2-(1-cyclohexenyl)ethylamine, and other compounds such as the alcohols containing unsaturation disclosed later in the Examples in this specification.
Exemplary suitable polymeric segments are homopolymers of 1,3-butadiene, or copolymers of ethylene, propylene and a diene. Poly(butadienes) are commercially available with hydroxyl-, amino-, halo-, and isocyanate-functionality.
The unsaturated oligomeric or polymeric segment may be any molecular weight and structure desired by the practitioner, provided it has at feast one carbon to carbon double bond for subsequent cross-linking. The oligomeric or polymeric segment may contain heteroatoms, such as, silicon, sulfur, nitrogen, or oxygen; may contain functional groups, such as hydroxyl, urea, carbamate, or ester; may contain cyclic or aromatic moieties. The at least one carbon to carbon double bond can be located within the oligomeric or polymeric backbone or chain, or pendant from the chain.
The silane segment will have the structure
in which n is simultaneously for each position 0, 1, or 2; R
1
is a methyl or ethyl group; R
2
is a vinyl group, an aromatic group, or a linear or branched alkyl group, preferably of 1 to 4 carbon atoms, and more preferably methyl or ethyl; A is a linear or branched alkyl group or a cyclic or aromatic group, and L is a linking group resulting from the reaction of a functional group on the silane precursor and a functional group on the oligomeric or polymeric precursor, with the proviso that neither functional group is an epoxy. There can be more than one silane segment per molecule of resin.
Examples of commercially available silanes suitable as precursors for the silane segment are gamma-isocyanatopropyltriethoxysilane, gamma-aminopropyltriethoxy-silane, gamma-aminopropyltrimethoxysilane, N-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane, triaminofunctional silane, bis-(gamma-trimethoxysilylpropyl)amine, N-phenyl-gamma-amino-propyltrimethoxysilane, N-beta-(aminoethyl)-gamma-aminopropylmethyldimethoxysilane, gamma-mercaptopropyl-trimethoxysilane, 3-aminopropyldimethylethoxysilane; 3-bromopropyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, dimethylmethoxychlorosilane, methyldimethoxysilane, and methyldiethoxysilane.
The resin is synthesized through a reaction between the precursor (also, hereinafer, starting material) for the unsaturated segment and the precursor for the silane segment. Although any appropriate synthetic route convenient to the practitioner may be used, suitable synthetic routes are through condensation or addition reactions between co-reactive functionalities, excluding epoxy, on the precursors. Examples of these reactions are illustrated later in this specification.
In one embodiment of the resin, the silane segment will be located at the termini of the oligomeric or polymeric segment and the at least one carbon to carbon double bond will be located within the oligomeric or polymeric chain or pendant from the chain. In this embodiment, the resin will have the structure
in which Q is an oligomeric or polymeric group containing at least one carbon to carbon double bond, derived from an oligomeric or polymeric precursor containing carbon to carbon unsaturation; n is simultaneously for each position 0, 1, or 2; R
1
is a methyl or ethyl group; R
2
is a vinyl group, an aromatic group, or a linear or branched alkyl group; A is a hydrocarbyl group, for example, a linear or branched alkyl group or a cyclic alkyl or alkenyl group, or an aromatic group; L is a linking group resulting from the reaction of a functional group, excluding epoxy, on the precursor for the segment containing silane and a functional group, excluding epoxy, on the precursor for the segment containing the at least one carbon to carbon double bond.
In another embodiment, the silane segment will be located at the termini of a polymeric chain and pendant from the polymeric chain. The polymeric segment will contain at least one carbon to carbon double bond located within the polymeric chain. The degree of substitution of silane onto pendant functionality can be controlled by reaction stoichiometry as desired by the practitioner. In this embodiment the adhesion promoting resin will have the structure:
in which Q, A, L, R
1
, and R
2
are as described before.
The functional groups on the oligomeric or polymeric precursors through which the silane is to be linked include hydroxyl, halide, amine, isocyanate, carboxylic acid, acid chloride, and vinyl double bonds. The functional groups on the silane precursor, for reaction with the functional groups on the oligomeric or polymeric precursor, include hydroxyl, amine, mercapto, isocyanate, halide, and a hydrosilation reactive hydrogen on a silicon atom. Consequently, it will be understood that the linking group can be a direct bond or an alkyl group, or can have a structure, such as
in which R
4
is hydrogen, an aromatic, or an alkyl group of 1 to 6 carbon atoms, and preferably is hydrogen, methyl or ethyl.
Within adhesive and enca
Feely Michael J
Gennaro Jane E.
National Starch and Chemical Investment Holding Corporation
Tucker Philip
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