Alkoxyhydridosiloxane resins

Details Alkoxyhydridosiloxane resins Alkoxyhydridosiloxane resins

2000-11-27

2002-06-04

Dawson, Robert (Department: 1712)

Stock material or miscellaneous articles

Composite

Of silicon containing

C528S029000, C528S031000, C528S033000, C521S154000, C427S245000, C427S387000

Reexamination Certificate

active

06399210

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to alkoxyhydridosiloxane resins and a method of making alkoxyhydridosiloxane resins by reacting a hydridosiloxane resin with an alcohol having about 10 to 28 carbon atoms. The alkoxyhydridosiloxane resin contains an average from 5 to 40 mole percent silicon bonded alkoxy groups and an average of at least 45 mole percent silicon bonded hydrogen atoms. The present invention also relates to nanoporous coatings produced from the alkoxyhydridosiloxane resins having a dielectric constant (Dk) ranging from about 1.5 to 3.
BACKGROUND OF THE INVENTION
Semiconductor devices often have one or more arrays of patterned interconnect levels that serve to electrically couple the individual circuit elements forming an integrated circuit (IC). The interconnect levels are typically separated by an insulating or dielectric coating. Previously, a silicon oxide coating formed using chemical vapor deposition (CVD) or plasma enhanced techniques (PECVD) was the most commonly used material for such dielectric coatings. However, as the size of circuit elements and the spaces between such elements decreases, the relatively high dielectric constant of such silicon oxide coatings (i.e. about 4) is inadequate to provide adequate electrical insulation.
In order to provide a lower dielectric constant than that of silicon oxide, dielectric coatings formed from siloxane-based resins have found use. An example of such coatings are those formed from hydrogen silsesquioxane resins as described for example in Collins et al., U.S. Pat. No. 3,615,272 and Haluska et al. U.S. Pat. No. 4,756,977. While such coatings provide lower dielectric constants than CVD or PECVD silicon oxide coatings and also provide other benefits such as enhanced gap filling and surface planarization, typically the dielectric constants of such coatings are limited to approximately 3 or greater.
Chung et al., U.S. patent application Ser. No. 09/197,249 describe a method for forming a porous coating from hydrogen silsesquioxane resins. A porous network is formed by depositing a coating on a substrate with a solution comprising a hydrogen silsesquioxane resin and a solvent in a manner in which at least 5 volume % of the solvent remains in the coating after deposition. The coating is then exposed to an environment comprising a basic catalyst and water; the solvent is evaporated from the coating to form a porous network with a dielectric constant in the range of about 1.5 to 2.4.
It is well known that the dielectric constant of insulating coatings is an important factor where IC's with low power consumption, cross talk, and signal delay are required. As IC dimensions continue to shrink, this factor increases in importance. As a result, siloxane based resin materials and methods for making such materials that can provide electrically insulating coatings with dielectric constants below 3 are desirable. In addition it is desirable to have siloxane-based resins and methods for making such resins that provide coatings which have a high resistance to cracking. Also, it is desirable for such siloxane-based resins to provide coatings by standard processing techniques.
It is known that the dielectric constant of solid coatings decrease with a decrease in density of the coating material. A porous coating typically has a lower density than a corresponding solid coating.
Kapoor, U.S. Pat. No. 5,494,859, describes an insulating layer for an integrated circuit structure and a method of making the layer. A porous layer is formed by depositing a composite layer on a structure comprising an insulating matrix material such as a polysilicon/carbon layer which can be converted to a porous SiO
2
layer by oxidation having a Dk of less than about 3.9, the carbon being oxidized to produce gaseous CO
2
, which may escape from the matrix.
Smith et al., WO 98/49721, describe a process for forming a nanoporous dielectric coating on a substrate. The process comprises the steps of blending an alkoxysilane with a solvent composition and optional water; depositing the mixture onto a substrate while evaporating at least a portion of the solvent; placing the substrate in a sealed chamber and evacuating the chamber to a pressure below atmospheric pressure; exposing the substrate to water vapor at a pressure below atmospheric pressure and then exposing the substrate to base vapor.
Mikoshiba et al., Japanese Laid-Open Patent (HEI) 10-287746, describe the preparation of porous coatings from siloxane-based resins having organic substituents that are oxidized at a temperature of 250° C. or higher. The useful organic substituents that can be oxidized at a temperature of 250° C. or higher that were disclosed include substituted and unsubstituted groups as exemplified by 3,3,3-triflouropropyl, &bgr;-phenethyl group, t-butyl group, 2-cyanoethyl group, benzyl group, and vinyl group.
Mikoskiba et al.,
J. Mat. Chem.,
1999, 9, 591-598, report a method to fabricate angstrom size pores in poly (methylsilsesquioxane) coatings in order to decrease the density and the dielectric constant of the coatings. Copolymers bearing methyl (trisiloxysilyl) units and alkyl (trisiloxysilyl) units are spin-coated on to a substrate and heated at 250° C. to provide rigid siloxane matrices. The coatings are then heated at 450° C. to 500° C. to remove thermally labile groups and holes are left corresponding to the size of the substituents. Trifluoropropyl, cyanoethyl, phenylethyl, and propyl groups were investigated as the thermally labile substituents.
It has now been found that nanoporous coatings produced from alkoxyhydridosiloxane resins wherein about 5 to 40 mole percent of total siloxane groups are substituted with at least one alkoxy group having about 10 to 28 carbon atoms and at least 45 mole percent of total siloxane groups are substituted with at least one hydrogen atom are useful for electrical insulating coatings. These nanoporous coatings have the advantage of using conventional thin coating processing and result in a dielectric constant in the range of about 1.5 to 3.0.
SUMMARY OF THE INVENTION
This invention relates to alkoxyhydridosiloxane resins and a method of making alkoxyhydridosiloxane resins by reacting a hydridosiloxane resin with an alcohol having about 10 to 28 carbon atoms using a base catalyst. The alkoxyhydridosiloxane resin contains an average from about 5 to 40 mole percent silicon bonded alkoxy groups and an average of at least 45 percent silicon bonded hydrogen atoms.
This invention further relates to a method of forming a nanoporous coating on a substrate by heating the alkoxyhydridosiloxane resin at a temperature sufficient to effect thermolysis of the alkoxy groups and thereby forming a nanoporous coating having a dielectric constant in the range of about 1.5 to 3.0.
DETAILED DESCRIPTION OF THE INVENTION
An alkoxyhydridosiloxane resin composition according to this invention comprises ROSiO
3/2
siloxane units and HSiO
3/2
siloxane units wherein R is an alkyl group having 10 to 28 carbon atoms, wherein the resin contains an average from 5 to 40 mole percent silicon bonded alkoxy groups, and wherein the resin contains an average of at least 45 mole percent silicon bonded hydrogen atoms.
While not represented by the structure, the resins may also contain a small number of siloxane units which have either 0 or 2 hydrogen atoms attached thereto and/or a small number of SiC groups such as CH
3
SiO
3/2
or HCH
3
SiO
2/2
groups. It is preferred that the alkoxyhydridosiloxane resin contain at least 70 mole percent silicon bonded hydrogen atoms.
The method for preparing the alkoxyhydridosiloxane resin comprises reacting a silicon bonded hydrogen of a hydridosiloxane resin with an alcohol having about 10 to 28 carbon atoms in the presence of a base catalyst for a time sufficient to effect formation of an alkoxyhydridosiloxane resin. The hydridosiloxane resin can be any of those known in the art where at least 50 percent of the silicon atoms have a hydrogen substitution and as such can be homopolymers or copolymers. The structure of the r

Affiliated with

Also associated with

Rating

Alkoxyhydridosiloxane resins does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Alkoxyhydridosiloxane resins, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Alkoxyhydridosiloxane resins will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2905631