Etching Method Selective Silicon Germanium Silicon
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Solution Overview
Problem
Current techniques cannot simultaneously selectively etch silicon-germanium (SiGe) with respect to silicon (Si) and silicon with respect to SiGe using the same apparatus and gas system, limiting their applicability in laminated structures.
Innovation Solution
An etching method that uses varying ratios of F2 and NH3 gases in the same gas system to selectively etch SiGe with respect to Si and Si with respect to SiGe, allowing for both processes to be performed in the same apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If different gas systems are used for selectively etching SiGe with respect to Si and Si with respect to SiGe, then high selectivity ratios are achieved, but the device complexity increases and the same apparatus cannot perform both etching processes
Solution Approach 1:
The patent applies universality by enabling a single gas system (CF4-based) to perform multiple etching functions: selectively etching SiGe with respect to Si, and selectively etching Si with respect to SiGe. By adjusting process parameters (gas composition ratios, power, pressure, temperature) within the same gas system, the apparatus achieves high selectivity ratios for both etching directions without requiring separate gas systems, thus reducing device complexity while maintaining manufacturing precision
Solution Approach 2:
The patent employs parameter changes by modifying the CF4 gas composition ratio (varying O2 and/or NF3 additions), power levels, pressure, and temperature to achieve different selectivity ratios. For example, adjusting the CF4:O2 ratio or CF4:NF3 ratio allows switching between selective SiGe etching and selective Si etching modes, enabling the same apparatus to perform both etching processes with high precision
2Manufacturing precision
If multiple separate apparatuses are used to perform selective SiGe etching and selective Si etching, then high manufacturing precision is maintained, but the loss of time increases due to multiple loading/unloading cycles
Solution Approach 1:
The patent merges the functionality of multiple separate etching apparatuses into a single apparatus by using a unified CF4-based gas system that can perform both selective SiGe etching and selective Si etching. This consolidation eliminates the need for intermediate loading and unloading of substrates between separate apparatuses, significantly reducing processing time while maintaining high etching selectivity through parameter optimization
Solution Approach 2:
The patent enables continuous processing by allowing the same apparatus to sequentially perform selective SiGe etching and selective Si etching without interrupting the vacuum environment or requiring substrate removal. By adjusting gas composition and process parameters between steps, the useful action of etching continues uninterrupted, eliminating time losses associated with multiple apparatus transitions
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
Enables efficient and selective etching of both SiGe and Si in the same apparatus, achieving high selectivity ratios and improving surface roughness by varying the gas ratios, thus addressing the limitations of existing methods.
Implementation Method 1
performing both of selectively etching the silicon-germanium with respect to the silicon and selectively etching the silicon with respect to the silicon-germanium by varying ratios of F2 gas and NH3 gas in an etching gas that has a gas system including F2 gas and NH3 gas
Data Source
AI summary
An etching method includes: disposing a target substrate including a silicon and a silicon-germanium within a chamber; and performing both of selectively etching the silicon-germanium with respect to the silicon and selectively etching the silicon with respect to the silicon-germanium by varying ratios of F2 gas and NH3 gas in an etching gas that has a gas system including the F2 gas and the NH3 gas.