Derivatization of silicon surfaces

Details Derivatization of silicon surfaces Derivatization of silicon surfaces

1999-04-16

2001-09-04

Dawson, Robert (Department: 1712)

Coating processes

Nonuniform coating

Applying superposed diverse coatings or coating a coated base

C427S126100, C427S261000, C427S265000, C427S307000, C427S314000, C427S383100, C427S383300, C427S384000, C427S385500, C427S419800, C428S304400, C428S307300, C428S312200, C428S312600, C428S373000, C428S457000, C428S543000, C423S347000, C502S407000, C438S584000

Reexamination Certificate

active

06284317

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to methods for derivatizing silicon-hydride terminated surfaces to form silicon-carbon bonds through the addition of organometallic reagents, and articles having surfaces containing silicon-carbon bonds where the carbon is part of a unit containing at least one unsaturated carbon atom. The present invention also relates to articles covalently attached to a polymer, in particular where the article is a semiconductor surface such as silicon.
BACKGROUND OF THE INVENTION
The highly reactive nature of single-element semiconductor surfaces, namely silicon surfaces, creates a continuing need and challenge for controlled derivatization of these surfaces. Such processes should be adaptable for automated production and thus should include features such as ease of chemical derivatization and low process costs. Moreover, any electronic or other chemical features of an article having a derivatized surface should be maintained after derivatization. For example, there is a heightened interest in porous silicon due to its luminescent properties, and promise of compatibility with current semiconductor fabrication schemes based on silicon. Thus, there is a need for facile methods for derivatizing this surface.
The formation of Group IV element surfaces covalently terminated with organic groups is one desired derivatization process, e.g., a surface having silicon-carbon bonds. Silicon-carbon bonds can be accessed through hydrogen-terminated surfaces (i.e., having silicon-hydride bonds). Typically, however, substitution of silicon-hydride bonds with silicon-carbon bonds requires intermediate process steps prior to addition of the carbon-containing reagent. In at least one known case, a chlorination pretreatment step is required at temperatures of at least 80° C. prior to silicon-carbon bond formation. The resulting chlorinated silicon surface is more sensitive to water and is not as easily manipulated compared to silicon-hydride surfaces. Other techniques for the formation of silicon-methyl surfaces are carried out through the addition of a Grignard reagent, CH
3
MgBr but only in the presence of a photo- or electrochemical stimulus.
In other applications, there remains a challenge to provide an intimate integration between semiconductors and conducting polymers for efficient electrical and optical coupling. Conducting polymers offer distinct advantages over other conducting materials in that the physical properties can be tailored in a relatively facile manner. Thus, unlike conventional metal/semiconductor contacts, the electrical properties can be manipulated through various parameters such as polymer type and dopant.
Typically, forming polymer/semiconductor junctions involves depositing the polymer on the semiconductor by spin-coating or electrochemical polymerization. In general, a high quality junction cannot be obtained by such traditional deposition techniques. The resulting junction often suffers from poor interfacial interactions that can diminish physical and electrical performance.
Other junctions have been formed with an intervening oxide layer. Simon et al. report an oxidized surface of silicon attached to a pyrrole-terminated alkylsiloxane monolayer via an oxide linkage and subsequently subjected to polymerization. The intervening oxide layer optimizes electrical and other physical properties of the polymer/semiconductor junction.
There remains a challenge to derivatize surfaces with various organic groups, in particular where the surface comprises a Group IV semiconductor. There also remains a need to lower costs for forming surfaces having silicon-carbon bonds.
SUMMARY OF THE INVENTION
The present invention provides methods for the derivatization of hydride-terminated surfaces that can be performed free of external energy sources to provide these methods with lower production costs and ease of use. Moreover, the methods allow the formation of Group IV element carbon bonds where the carbon is attached to a wide variety of units, such as polymers to provide polymer-modified surfaces.
One aspect of the present invention provides a method for forming a surface having a silicon-carbon bond. At least a portion of the surface comprises Si
x
H
y
units where H is bonded to Si, x is greater than zero and y is greater than zero. A silicon-carbon bond is formed on the at least a portion of the surface at a temperature of less than about 25° C. free of an external energy source.
Another aspect of the present invention provides a method for forming a surface having at least a portion of the surface comprising a formula Si
x
H
y
. H is bonded to Si, x is greater than zero and y is greater than zero. The at least a portion of the surface is exposed to an organometallic reagent to form a silicon-metal bond on the at least a portion of the surface.
Another aspect of the present invention provides an article. The article has a surface having at least a portion of the surface comprising a formula Si
x
H
y
—MX
n
. M is a metal, H is bonded to Si, x is greater than zero, y is greater than zero, X is an anion and n is at least 0.
Another aspect of the present invention provides an article having a surface where at least a portion of the surface has a silicon-carbon bond. A carbon atom of the silicon-carbon bond is attached to a unit having at least one unsaturated carbon atom.
Another aspect of the present invention provides an article comprising a semiconductor material. A surface of the article is hydrogen-terminated and covalently attached to a polymer.
Another aspect of the present invention provides an article comprising a semiconductor material. A surface of the article is substantially free of oxidation and is covalently attached to a polymer.
Another aspect of the present invention provides a method for covalently attaching a polymer to a surface. The method involves providing a hydrogen-terminated surface and reacting the surface with a reagent where the reagent includes a reactive functional group. A polymer is then deposited on the surface.
Other advantages, novel features, and objects of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings, which are schematic and which are not intended to be drawn to scale. In the figures, each identical or nearly identical component that is illustrated in various figures is represented by a single numeral. For purposes of clarity, not every component is labeled in every figure, nor is every component of each embodiment of the invention shown where illustration is not necessary to allow those of ordinary skill in the art to understand the invention.


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patent: 5017540 (1991-05-01), Sandoval et al.
patent: 5326738 (1994-07-01), Sandoval et al.
patent: 5908692 (1999-06-01), Hamers et al.
patent: 6132801 (2000-10-01), Linford
Simon et al., “Synthesis and Characterization of a New Surface Derivatizing Reagent to Promote the Adhesion of Polyryrrole Films to n-Type Silicon Photoanodes N-(3-Trimethoxysilyl)propyl)pyrrole,”J. Am. Chem. Soc., 1982, 104, 2031-2034.
Willicut and McCarley, “Surface-Confined Monomers on Electrode Surfaces. 1. Electrochemical and Microscopic Characterization of &ohgr;-(N-Pyrrolyl)alkanethiol Self-Assembled Monolayers on Au,”Langmuir, 1995, 11, 296-301.
Sayre and Collard, “Self-Assembled Monolayers of Pyrrole-Containing Alkanethiols on Gold,”Langmuir, 1995, 11, 302-306.
Rubinstein et al., “Morphology Control in Electrochemically Grown Conducting Polymer Films. 1. Precoating The Metal Substrate with an Organic Monolayer,”J . Am. Chem. Soc., 1990, 112, 6135-6136.

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