Flowable CVD Low-K Film Precursors for Void-Free Gap Fill
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Solution Overview
Problem
Existing flowable chemical vapor deposition methods using trisilylamine (TSA) result in silicon-containing films with high Si—H bond density, leading to fast wet etch rates and voids or cracks in hardened materials, making them unsuitable for low-k film applications.
Innovation Solution
The use of silicon-containing compounds with acetoxy groups, such as acyloxysilanes, acyloxyalkoxysilanes, and acyloxyaminoxysilanes, reacted in a plasma environment to form flowable liquid oligomers, which are then thermally treated and exposed to UV or plasma to create dense, porous silicon-containing films with improved mechanical integrity and porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If trisilylamine (TSA) is used as precursor in flowable CVD, then silicon-containing films can be deposited, but the films have high Si-H bond density leading to fast wet etch rates and voids or cracks
Solution Approach 1:
The patent changes the chemical composition parameters of the precursor from trisilylamine (TSA) to acyloxysilane compounds. This parameter change fundamentally alters the bonding characteristics of the deposited film, reducing Si-H bond density and eliminating the associated problems of fast etch rates and structural defects while maintaining the flowable deposition process.
Solution Approach 2:
The patent extracts and removes the problematic Si-H bonding characteristic from the film structure by using alternative precursor chemistry. The acyloxysilane precursors produce films with different bond structures that do not exhibit the harmful Si-H related properties, effectively taking out the harmful factor while preserving the useful flowable deposition mechanism.
2Volume of moving object
If flowable liquid film is formed to fill surface features, then gap fill capability is achieved, but voids or cracks form in hardened materials
Solution Approach 1:
The patent changes the chemical composition parameters of the precursor from trisilylamine (TSA) to acyloxysilane compounds. This parameter change fundamentally alters the bonding characteristics of the deposited film, reducing Si-H bond density and eliminating the associated problems of fast etch rates and structural defects while maintaining the flowable deposition process.
Solution Approach 2:
The patent extracts and removes the problematic Si-H bonding characteristic from the film structure by using alternative precursor chemistry. The acyloxysilane precursors produce films with different bond structures that do not exhibit the harmful Si-H related properties, effectively taking out the harmful factor while preserving the useful flowable deposition mechanism.
3Productivity
If high Si-H bond density is present in deposited films, then flowable deposition can be achieved, but wet etch rates become too fast for low-k applications
Solution Approach 1:
The patent changes the chemical composition parameters of the precursor from trisilylamine (TSA) to acyloxysilane compounds. This parameter change fundamentally alters the bonding characteristics of the deposited film, reducing Si-H bond density and eliminating the associated problems of fast etch rates and structural defects while maintaining the flowable deposition process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method produces silicon-containing films with mechanical integrity, porosity, and dielectric constants suitable for low-k applications, achieving void-free gap fill in high aspect ratio features.
Implementation Method 1
providing a plasma into the reactor to at least partially react the at least one silicon-containing compound to form a flowable liquid oligomer
Implementation Method 2
Flowable chemical vapor deposition (FCVD) methods typically use alkoxysilane compounds as precursors for silicon-containing films
Implementation Method 3
the flowable film is formed by reacting a dielectric precursor which may have a Si—C bond with an oxidant to form the dielectric material. In certain embodiments, the dielectric precursor condenses and subsequently reacts with the oxidant
Implementation Method 4
subjecting the coating to a thermal treatment at one or more temperatures between about 100° C. to about 1000° C. to densify at least a portion of the coating and form a hardened layer
Implementation Method 5
exposed to UV or plasma to create dense, porous silicon-containing films with improved mechanical integrity and porosity
Data Source
AI summary
A method for depositing a silicon-containing film, the method comprising: placing a substrate comprising at least one surface feature into a flowable CVD reactor which is at a temperature of from about −20° C. to about 100° C.; increasing pressure in the reactor to at least 10 torr; and introducing into the reactor at least one silicon-containing compound having at least one acetoxy group to at least partially react the at least one silicon-containing compound to form a flowable liquid oligomer wherein the flowable liquid oligomer forms a silicon oxide coating on the substrate and at least partially fills at least a portion of the at least one surface feature. Once cured, the silicon oxide coating has a low k and excellent mechanical properties.