HWCVD Silicon Film Deposition via Dynamic Gas Flow Control
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Solution Overview
Problem
Conventional hot wire chemical vapor deposition (HWCVD) processes for depositing materials, such as silicon-based opto-electronic grade films, often result in films with poor optical properties, specifically a low visible energy range absorption coefficient.
Innovation Solution
The method involves exposing a substrate to a silicon-containing gas and a reducing gas, with increasing flow rates of the silicon-containing gas and decreasing flow rates of the reducing gas to form a first layer, and repeating this process until the desired thickness is achieved, allowing for improved control over the material's crystalline or amorphous state and optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional HWCVD processes are used to deposit silicon-based films, then the deposition process is simple and straightforward, but the films exhibit poor optical properties with low visible energy range absorption coefficient
Solution Approach 1:
The patent applies dynamics by continuously varying the flow rates of precursor gases during deposition. Specifically, the silicon-containing gas flow rate is increased while the reducing gas flow rate is decreased over time, creating a dynamic process that evolves the film's optical properties during deposition rather than maintaining static conditions throughout.
Solution Approach 2:
The patent implements parameter changes by modifying gas flow rates as key process parameters. The silicon-containing gas flow rate is increased from an initial value, while the reducing gas flow rate is decreased, thereby changing the chemical environment during deposition to improve the absorption coefficient of the deposited film.
2Manufacturing precision
If the flow rate of silicon-containing gas is increased and reducing gas is decreased to improve optical properties, then the visible energy range absorption coefficient is enhanced, but the process control becomes more complex
Solution Approach 1:
The patent applies periodic action by implementing cyclic variations in gas flow rates during the deposition process. The flow rates are adjusted in a systematic periodic manner, allowing the film to be deposited in stages with varying optical properties, which can be repeated to achieve the desired overall film characteristics.
Solution Approach 2:
The patent maintains continuity of useful action by ensuring that the deposition process continues without interruption while the gas flow rates are dynamically adjusted. This allows the film to be continuously deposited with improving optical properties throughout the process, maximizing the efficiency of the deposition time.
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
This approach enhances the visible energy range absorption coefficient of the deposited films while maintaining consistent electronic properties, such as dark conductivity and photo response, compared to conventionally deposited materials.
Implementation Method 1
one or more precursor gases are thermally decomposed at a high temperature within a process chamber proximate a substrate upon which a desired material is to be deposited
Implementation Method 2
The thermal decomposition reaction is facilitated within the process chamber by one or more wires, or filaments, supported in the process chamber that may be heated to a desired temperature, for example, by passing electrical current through the filaments
Implementation Method 3
flowing a reducing gas into the HWCVD chamber at a second flow rate for a second period of time to form a second species that reacts with the substrate disposed in the HWCVD chamber
Data Source
AI summary
Methods for depositing a material atop a substrate are provided herein. In some embodiments, a method of depositing a material atop a substrate may include exposing a substrate to a silicon containing gas and a reducing gas; increasing a flow rate of the silicon containing gas while decreasing a flow rate of the reducing gas to form a first layer; and depositing a second layer atop the first layer.