Stock material or miscellaneous articles – Composite – Of quartz or glass
Reexamination Certificate
1999-12-23
2004-07-13
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
Composite
Of quartz or glass
C428S446000, C428S450000, C428S447000, C528S010000, C528S025000, C528S026000, C528S031000, C528S033000, C528S034000, C525S474000
Reexamination Certificate
active
06761975
ABSTRACT:
BACKGROUND OF THE INVENTION
a) Field of the Invention
The present invention relates to low dielectric constant (low k) polymer compositions and more particularly to the use of polycarbosilane materials to enhance the adhesion of low k polymer coatings to adjacent substrates.
b) Related Art
In the prior art fabrication of semiconductor integrated circuit devices, fine patterns of circuitry in the form of semiconductor regions, electrodes, wiring and other components are fabricated onto a semiconductor substrate by using conventional processing, such as etch and chemical vapor deposition (CVD) processes, among others. After formation of a wire pattern on the substrate layer, an interline dielectric material deposition process ensues to both fill in the spaces between the horizontally disposed wiring and overcoat the pattern. Alternatively, a damascene technique can be performed in which a dielectric layer is deposited onto a substrate, patterned, and etched back to create recessed regions in which metal is inlaid to create interconnect wiring. These deposition steps as well as other multi-layer formation processes, well-known in the art, are provided to form a multi-layered integrated semiconductor device.
As the electronics fabrication industry moves towards more compact circuitry with finer circuit or line geometry in densely-packed circuit patterns, the dielectric constant requirements of the insulating layers grows more demanding for lower values. Under these circumstances, the use of low k polymer dielectrics that minimize capacitance and reduce power consumption and cross talk, while increasing signal propagation speed, becomes a necessity. The dielectric materials must possess dielectric constants no higher than 3.0 and should have dielectric constants as low as possible toward a theoretical limit of 1.0. The practical expectation for polymer dielectrics is in the range of 2.2 to 3.0. For organic dielectrics, thermal stability is an important consideration, as semiconductor processing can involve exposure to temperatures in excess of 400° C. The organic dielectrics must have glass transition temperatures above 300° C. and as high as possible towards 450° C., as well as a decomposition temperature in excess of 450° C. Preferably, the organic polymers should be easily processed by standard spin-bake-cure processing techniques. The organic dielectrics should also be free from moisture and out-gassing problems, in addition to having expected adhesive and gap-filling qualities, and dimensional stability towards thermal cycling, etching, and chemical mechanical polishing.
Various polymers have been proposed and utilized as dielectric materials for integrated circuits, such polymers including polyimides, and arylene ether polymers. Polyimide resins generally demonstrate high moisture absorption due to their polarizing chemical structures, resulting in an increasing dielectric constant. Organosilicon polymers have also been identified as low dielectric constant materials. In particular, siloxane based resins including hydridosiloxane resins, organohydridosiloxane resins, and spin-on glass siloxanes and silsesquioxanes are used as dielectric layers. Other classes of organosilicon materials include polyperhydrido-silazanes and nanoporous dielectric silica coatings formed from liquid alkoxysilane compositions. Most of these materials exhibit difficulties in processing due to chemical or mechanical instability.
Arylene ether polymers have been found particularly useful as low k dielectric materials in IC applications. Arylene ether polymers have been identified as organic dielectric materials and include poly (arylene ether) (PAE), poly (arylene ether ether ketone) (PAEEK), poly (arylene ether ether acetylene) (PAEEA), poly (arylene ether ether acetylene ether ether ketone) (PAEEAEEK), poly (arylene ether ether acetylene ketone) (PAEEAK), and poly (naphthylene ether) (PNE) comprising different polymer designs that include homopolymers, block or random copolymers, polymer blends, interpenetrating polymer networks (IPNs), and semi-interpenetrating polymer networks (SIPNs). Other examples of organic dielectric materials in current use include the polymeric material obtained from the phenylethynylated aromatic monomer provided by Dow Chemical Company under the trademark SILK™ and the poly (arylene ether) provided by Schumacher under the tradename VELOX™.
In commonly assigned U.S. patent applications Ser. No. 08/665,189, filed on Jun. 14, 1996, and Ser. No. 09/197,478, filed on Dec. 12, 1997, there are disclosed certain poly(arylene ethers) which have low dielectric constants, high glass transition (Tg) temperatures, good thermal stability to and above the Tg, low moisture absorption rate, and good storage modulus retention. However, adhesion of these and the other cited organic polymer insulators to substrate surfaces have been found in need of enhancement, generally requiring addition (or primer application) of known adhesion promoters. These prior art adhesion promoters have been found generally unacceptable in combination with the dielectric poly(arylene ethers) and other organic dielectrics because: (1) their primer application generally requires a separate coating process step; and (2) their presence may generate unanticipated chemical side reactions (e.g. generation of volitiles due to materials breakdown) during IC high temperature processing.
It has presently been discovered that certain polycarbosilanes can be used as compatible a adhesion promoters for low dielectric constant polymers, particularly poly(arylene ethers), and can be used as an additive with these polymers and processed to form modified low k dielectric polymeric coating compositions with enhanced adhesive characteristics. More precisely, it has been found that the adhesion of poly(arylene ether) dielectric coating compositions is particularly enhanced by the primer application or compositional addition of an adhesion promoter material comprising at least one polycarbosilane. The instant polycarbosilane adhesion promoters can be employed as a surface deposition treatment (primer) or as an internal compositional additive to dielectric polymer compositions. These polycarbosilane promoters can be prepared, provided or used at reasonable cost; and provide enduring adhesion to a variety of surfaces.
SUMMARY OF THE INVENTION
The present invention provides new and improved adhesion promoting materials effective in enhancing the adhesion of low dielectric constant polymer compositions to various substrates. The new and improved adhesion promoter composition comprises a polycarbosilane of the formula:
in which:
R
1
, R
7
, and R
10
each independently represents a substituted or unsubstituted alkylene, cycloalkylene, or arylene group;
R
2
, R
3
, R
4
, R
5
, R
8
and R
9
each independently represents a hydrogen atom or organic group.
R
6
represents an organosilicon, a silanyl, a siloxyl, or an organo group; and
x, y, z and w satisfying the conditions of [4≦x+y+z+w≦100,000], and y and z and w can collectively or independently be zero.
In order to improve the adhesion of low dielectric constant polymer coatings to electronic surfaces, substrates such as silicon, silicon dioxide, silicon nitride and aluminum are treated with the instant polycarbosilanes as adhesion promoters in two different forms. The polycarbosilane materials can be added to surfaces as primer coatings from a solution containing typically from about 0.05 to 20% by weight of the polycarbosilane promoter. Alternatively and preferably, the polycarbosilane adhesion promoters can be compositionally added to a low k dielectric polymer in certain concentrations and effect in-situ adhesion capability in the cured or dried polymer coating composition. When used as surface primers, the present polycarbosilane adhesion promoter compounds engender superior bonding capacity to substrate surfaces to which low k polymer coatings are subsequently applied. In more preferred embodiments, the polycarbosilane adhesion promoter compounds are a
Chen Tian-An
George Anna M.
Lau Kreistler S. Y.
Wu Hui-Jung
Fish Robert D.
Rutan & Tucker LLP
Stein Stephen
Thompson Sandra P.
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