Polycrystalline Silicon Film Deposition With Crystallinity Control
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Solution Overview
Problem
Existing methods for forming silicon films lack effective control over crystallinity, which affects the performance of transistors when used as channel layers.
Innovation Solution
A film-forming method involving the sequential supply of silicon-containing gases, including an impurity-containing gas like ethylene, to form a bulk layer, followed by thermal treatment, allowing control over the crystallinity of the polycrystalline silicon film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a silicon-containing gas is supplied to form a bulk layer over a seed layer, then a polycrystalline silicon film is formed, but the crystallinity and crystal grain size cannot be effectively controlled
Solution Approach 1:
The bulk layer formation process is segmented into multiple stages by introducing impurity-containing gas during specific periods of silicon-containing gas supply. This allows different regions of the bulk layer to have different impurity concentrations, enabling control over crystal grain size and crystallinity in different zones of the film.
Solution Approach 2:
The patent applies local quality by creating regions with different impurity concentrations within the bulk layer. By controlling the timing and amount of impurity-containing gas supply, specific areas of the film achieve desired crystallinity and crystal grain size characteristics tailored to local requirements.
2Manufacturing precision
If impurity-containing gas is supplied during bulk layer formation, then crystal grain size and crystallinity are controlled, but the process complexity increases
Solution Approach 1:
The patent employs periodic action by supplying impurity-containing gas during specific periods of the bulk layer formation process. The impurity-containing gas is supplied intermittently or in controlled intervals rather than continuously, allowing precise control over impurity distribution and resulting crystal properties.
Solution Approach 2:
The patent utilizes parameter changes by adjusting the timing, duration, and concentration of impurity-containing gas supply during bulk layer formation. By varying these parameters, the process controls impurity concentration profiles, which directly influence crystal grain size and carrier mobility in the resulting polycrystalline silicon film.
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 enhances carrier mobility in polycrystalline silicon films, improving transistor performance by controlling crystal grain size and crystallinity.
Implementation Method 1
supplying a silicon-containing gas to the substrate and forming, over the seed layer, a bulk layer containing silicon
Implementation Method 2
The formation of the bulk layer includes supplying an impurity-containing gas during at least a part of a supply period of the silicon-containing gas
Implementation Method 3
thermally treating the substrate and crystallizing the bulk layer
Implementation Method 4
thermally treating the substrate and crystallizing the bulk layer
Data Source
AI summary
A film-forming method includes forming a seed layer over a substrate; supplying a silicon-containing gas to the substrate and forming, over the seed layer, a bulk layer containing silicon; and thermally treating the substrate and crystallizing the bulk layer. The formation of the bulk layer includes supplying an impurity-containing gas during at least a part of a supply period of the silicon-containing gas.