Low Temperature Semiconductor Etching via Hydrogen Gas Mediation
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Solution Overview
Problem
Conventional silicon etching processes require high temperatures, leading to accelerated electron diffusion and device characteristic deterioration in semiconductor substrates, and are incompatible with low-temperature metal curing processes.
Innovation Solution
A method involving a mixture of chemically reactive gases, where a first gas (such as HCl) is combined with a second gas containing hydrogen atoms (like GeH4 or SiH4), allowing etching at lower temperatures (500-700°C) to reduce substrate damage and enable etching of silicon, germanium, and silicon-germanium substrates while forming epitaxial layers in-situ.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high temperature (about 800 degrees C.) is used for Si etching with HCl gas, then etching can be performed, but electron diffusion is excessively accelerated and device characteristics deteriorate
Solution Approach 1:
The patent changes the temperature parameter from conventional high temperature (800°C) to low temperature (500-700°C) by introducing a hydrogen-containing gas (H2, SiH4, GeH4) into the etching atmosphere. This parameter change enables etching to proceed at lower temperatures where electron diffusion is reduced, thereby maintaining device characteristics while achieving the desired etching effect.
Solution Approach 2:
The hydrogen-containing gas acts as an intermediary substance that modifies the etching chemistry. The hydrogen gas introduces hydrogen atoms that facilitate the etching reaction at lower temperatures, serving as a mediator between the HCl gas and the silicon substrate, enabling low-temperature etching without requiring conventional high temperature conditions.
2Manufacturing precision
If high temperature process is used for Si etching, then etching can be performed, but it is incompatible with low-temperature metal curing process
Solution Approach 1:
The patent changes the temperature parameter from high (800°C) to low (500-700°C), which resolves the conflict with metal curing processes. This parameter change allows the etching process to be performed at temperatures compatible with low-temperature metal curing, enabling both processes to be integrated in the same fabrication sequence without temperature conflicts.
3Manufacturing precision
If HCl gas is used for etching, then Si etching can be performed, but high temperature (about 800 degrees C.) is required which causes electron diffusion
Solution Approach 1:
The hydrogen-containing gas serves as an intermediary that modifies the etching mechanism. By introducing H2, SiH4, or GeH4 into the system, hydrogen atoms are provided that enable the etching reaction to proceed through a different chemical pathway at lower temperatures, reducing the temperature requirement from 800°C to 500-700°C while maintaining etching effectiveness.
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 effectively reduces semiconductor device characteristic deterioration by etching at lower temperatures, maintaining device performance and allowing for integration with metal curing processes.
Implementation Method 1
providing a first gas that is chemically reactive with respect to the semiconductor substrate, and while providing the first gas, providing a second gas different than the first gas. More particularly, a molecule of the second gas may include a hydrogen atom, and the second gas may lower a temperature at which the first gas chemically reacts with the semiconductor substrate
Implementation Method 2
The second gas may accelerate a chemical decomposition of the first gas, and the mixture of the first and second gases may be provided adjacent the semiconductor substrate at a temperature in the range of about 500 degrees C. to about 700 degrees C.
Implementation Method 3
A chemical vapor etching (CVE) process using HCl gas may be performed in-situ with an epitaxial growth process
Data Source
AI summary
Methods of etching a semiconductor substrate may include providing a first gas that is chemically reactive with respect to the semiconductor substrate, and while providing the first gas, providing a second gas different than the first gas. More particularly, a molecule of the second gas may include a hydrogen atom, and the second gas may lower a temperature at which the first gas chemically reacts with the semiconductor substrate. The mixture of the first and second gases may be provided adjacent the semiconductor substrate to etch the semiconductor substrate.