Thermal F2 SiGe Etching With Additives for Selective Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing plasma-driven and thermally-driven etching processes for silicon germanium (SiGe) in semiconductor fabrication suffer from poor selectivity and non-uniformity, leading to suboptimal etch rates and device geometry constraints.
Innovation Solution
A thermally-driven etching process using F2 in combination with various additives, such as oxidizing and reducing reactants, to selectively etch SiGe over silicon, employing alternating exposure and pulsing techniques to achieve uniformity and high throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma-driven etching is used to etch silicon germanium, then etch rate is improved, but selectivity and uniformity deteriorate
Solution Approach 1:
The patent replaces plasma-driven etching (which uses ion bombardment and chemical reactions) with a thermal field-based etching process using F2 gas. This substitution eliminates the mechanical/physical aspects of plasma ion bombardment that cause non-uniform etching and poor selectivity, while maintaining high etch rates through thermal activation of the F2 etching reaction.
Solution Approach 2:
The patent changes the fundamental etching mechanism from plasma-driven to thermally-driven by controlling temperature parameters. By maintaining the substrate at elevated temperatures (e.g., 20-100°C or higher) during F2 exposure, the etching reaction is activated thermally rather than through plasma, achieving both high etch rates and superior uniformity/selectivity.
2Manufacturing precision
If thermally-driven etching with F2 is used to etch silicon germanium, then selectivity is improved, but etch rate and uniformity deteriorate
Solution Approach 1:
The patent introduces an intermediary substance (additive) that mediates between the F2 gas and the silicon germanium substrate. The additive enhances the etching reaction efficiency and uniformity while maintaining the selective etching of SiGe over silicon, thereby improving both etch rate and uniformity without sacrificing selectivity.
Solution Approach 2:
The patent optimizes temperature parameters to enhance the thermal etching process. By controlling and maintaining specific temperature ranges during F2 exposure, the etching reaction rate is increased while preserving selectivity and improving uniformity across the substrate surface.
3Loss of time
If conventional etching processes are used, then processing time is reduced, but etch uniformity and quality deteriorate
Solution Approach 1:
The patent replaces conventional plasma-driven etching processes with a thermal field-based F2 etching process. This substitution enables faster processing times while simultaneously achieving superior etch uniformity and quality by eliminating the non-uniform ion bombardment inherent in plasma processes.
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 provides a more uniform and selective etch rate for SiGe, addressing non-uniformity issues and enabling high-quality etching with improved device geometry and throughput.
Implementation Method 1
A thermally-driven etching process using F2 in combination with various additives, such as oxidizing and reducing reactants, to selectively etch SiGe over silicon
Implementation Method 2
exposing the substrate to F2 and to an additive, where exposing the substrate to F2 and to the additive results in selectively etching the silicon germanium compared to the silicon
Implementation Method 3
the additive may adsorb onto the substrate
Data Source
AI summary
Embodiments herein relate to methods, apparatus, and systems for selectively etching a substrate. The substrate typically includes one or more layers of silicon and one or more layers of silicon germanium. The method may involve receiving the substrate in a process chamber; exposing the substrate to F2; and exposing the substrate to an additive, where exposing the substrate to F2 and to the additive results in selectively etching the silicon germanium compared to the silicon, and where the substrate is not exposed to plasma while exposed to F2. Use of the additive produces a more uniform etch rate for the material being etched than would otherwise be achieved in the absence of the additive.