Acetoxy Silane Flowable CVD for Low-K Film Gap Fill
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Solution Overview
Problem
Flowable oxide films deposited from trisilylamine in gas phase polymerization processes have high Si—H bond density and rapid wet etch rates, making them unsuitable for low-k film applications, and often result in films with voids and cracks after hardening processes.
Innovation Solution
The use of silicon-containing compounds with acetoxy groups, such as acyloxysilanes, acyloxyalkoxysilanes, and acyloxyaminoxysilanes, in a flowable chemical vapor deposition process, followed by plasma reaction and thermal treatment to form a silicon-containing film with desired mechanical integrity and porosity, and subsequent exposure to energy sources for final film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If trisilylamine is used as precursor in gas phase polymerization, then silicon-containing film can be deposited, but the film has high Si-H bond density and rapid wet etch rate making it unsuitable for low-k applications
Solution Approach 1:
The patent changes the chemical composition parameters of the precursor by using acetoxy groups instead of amine groups. This fundamental chemical parameter change transforms the film properties: the acetoxy-containing precursors produce films with lower Si-H bond density and slower wet etch rates, making them suitable for low-k applications while maintaining the flowable CVD deposition capability
Solution Approach 2:
The acetoxy groups serve as temporary functional groups that are intentionally introduced for the deposition process and then removed during subsequent thermal treatment. These groups enable the flowable film formation but are designed to be transient, converting to volatile byproducts during thermal processing, thus leaving a clean final film structure suitable for low-k applications
2Strength
If hardening process is applied to flowable films, then mechanical strength is improved, but voids and cracks form in the film
Solution Approach 1:
The patent intentionally creates a controlled porous structure in the final low-k film through the thermal decomposition of acetoxy groups. This controlled porosity provides mechanical strength while preventing the formation of large voids and cracks. The porous structure is uniformly distributed and designed to maintain film integrity, achieving both mechanical strength and manufacturing precision
Solution Approach 2:
The flowable film is deposited with acetoxy groups that serve as preliminary structural elements. These groups are strategically placed and then uniformly removed through controlled thermal treatment before final film formation. This preliminary action allows the film to maintain structural integrity during processing while achieving the desired mechanical properties in the final product
3Volume of moving object
If flowable film is formed to fill surface features, then gap fill capability is achieved, but film may contain voids and cracks
Solution Approach 1:
The patent changes the chemical parameters of the precursor (using acetoxy groups) to achieve optimal viscosity and flow characteristics. This enables complete gap fill capability while the controlled thermal decomposition of these groups creates a uniform porous structure that prevents void and crack formation, thus achieving both volume fill and high film quality
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 and improved mechanical properties.
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 wherein the flowable liquid oligomer forms a coating on the substrate
Implementation Method 2
the flowable liquid oligomer forms a coating on the substrate and at least partially fills at least a portion of the at least one surface feature
Implementation Method 3
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
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.