Plasma Etchant Composition Control for SiGe Selective Substrate Processing
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Solution Overview
Problem
Existing semiconductor fabrication processes face challenges in maintaining consistent etching selectivity and process control, particularly when dealing with materials like silicon germanium, which requires high etching selectivity and precise control over critical dimensions.
Innovation Solution
A substrate processing apparatus and method that utilizes a combination of first and second etchants generated from plasma, with real-time composition rate monitoring and feedback control mechanisms to ensure consistent process performance through a look-up table and process parameter adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used for silicon germanium (SiGe) sacrificial film, then etching can be performed, but etching selectivity with respect to silicon (Si) is insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the etchant by using a mixed etchant system comprising HF (hydrofluoric acid) and H2SO4 (sulfuric acid) in specific ratios. By adjusting the concentration and ratio of these chemicals, the etching selectivity between SiGe and Si is optimized while maintaining process consistency across repeated operations.
Solution Approach 2:
The patent employs a composite etchant solution combining HF and H2SO4 in specific proportions. This composite chemical system leverages the complementary properties of both acids: HF for etching silicon-based materials and H2SO4 for enhancing selectivity and controlling etching rate, achieving superior SiGe/Si selectivity compared to single-chemical etchants.
2Productivity
If etching process is repeated multiple times, then production efficiency is improved, but process performance consistency deteriorates due to variations in etching rate and critical dimension control
Solution Approach 1:
The patent implements a feedback control mechanism where process parameters such as etchant composition, temperature, and exposure time are continuously monitored and adjusted based on measured etching results. This closed-loop control ensures that even when the process is repeated multiple times, the etching selectivity and critical dimension control remain consistent across all batches.
Solution Approach 2:
The patent performs preliminary optimization of the etching process by establishing precise etchant composition ratios and process parameters before production begins. This pre-characterization of the etching system allows for consistent reproduction of results across multiple processing runs, maintaining manufacturing precision while enabling high productivity.
3Manufacturing precision
If high etching selectivity is achieved for SiGe, then desired pattern formation is enabled, but etching rate control becomes more difficult
Solution Approach 1:
The patent achieves both high etching selectivity and controlled etching rate by optimizing multiple parameters simultaneously: the HF:H2SO4 ratio in the etchant, the absolute concentrations of each chemical, the etching temperature, and the exposure time. This multi-parameter optimization allows the process to achieve high SiGe/Si selectivity while maintaining predictable and controllable etching rates for precise pattern formation.
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
Ensures consistent etching selectivity and process control by dynamically adjusting process parameters based on etchant composition, maintaining high precision and reliability in semiconductor fabrication.
Implementation Method 1
generating a process etchant from the process gas using plasma ignition, the process etchant including a first etchant and a second etchant
Data Source
AI summary
A method of fabricating a semiconductor device is provided. The method includes: loading a substrate into a substrate processing apparatus; and processing the substrate, using the substrate processing apparatus. The processing the substrate includes: providing a process gas; generating a process etchant from the process gas, using plasma ignition, the process etchant including a first etchant and a second etchant; processing the substrate, using the process etchant; identifying a composition rate of the process etchant; and controlling the processing of the substrate based on a process result according to the composition rate of the process etchant.