Pressurized Etching Gas Pulses for Selective SiGe Film Removal
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Solution Overview
Problem
Existing etching methods fail to selectively etch SiGe films without also etching adjacent semiconductor films due to the permeability of etching gases through porous films, leading to unintended damage.
Innovation Solution
An etching method involving a pressurized gas storage and rapid release mechanism, where etching gas is stored in a reservoir and quickly diffused into the processing container, followed by rapid closure and evacuation to minimize exposure to semiconductor films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If etching gas is supplied continuously to etch the SiGe film, then the etching of the first film is improved, but the semiconductor film is also etched through the porous film
Solution Approach 1:
The patent applies periodic action by supplying etching gas in repeated cycles rather than continuously. Each cycle consists of: (1) supplying etching gas to etch the SiGe film, (2) stopping gas supply and exhausting the processing container, (3) repeating the process. This periodic on-off cycling allows the etching front to advance through the SiGe film while giving time for gas exhaustion between cycles, preventing accumulation of etching gas that would otherwise penetrate the porous film and damage the semiconductor film.
Solution Approach 2:
The patent applies the skipping principle by rapidly transitioning between etching and exhaustion phases. The etching gas is supplied in short bursts to quickly etch through the SiGe film, then immediately stopped and the container exhausted. This rushing through the etching process in quick succession minimizes the total exposure time of the semiconductor film to etching gas, allowing the etching to complete its function before harmful penetration can occur.
2Length of moving object
If the etching gas supply time is extended to complete SiGe film etching, then the etching depth is improved, but the exposure time to semiconductor film increases causing damage
Solution Approach 1:
The periodic cycling of etching gas supply and exhaustion allows progressive deepening of etching depth over multiple cycles. Each cycle contributes to advancing the etching front deeper into the SiGe film, while the exhaustion phase between cycles resets the gas concentration, preventing continuous exposure that would damage the semiconductor film. This achieves deep etching without proportionally increasing harmful exposure time.
Solution Approach 2:
The patent maintains continuity of useful action by repeating the etching cycle multiple times. Rather than using a single long etching exposure that would damage the semiconductor film, the useful etching action is continued across multiple shorter cycles, accumulating the desired etching depth while intermittently removing harmful gas through exhaustion phases.
3Quantity of substance
If porous film permeability is increased to allow gas flow, then the etching gas can reach the SiGe film, but the gas also reaches and etches the semiconductor film
Solution Approach 1:
The periodic supply and exhaustion of etching gas exploits the porous film's permeability beneficially. During the supply phase, gas flows through the porous film to reach and etch the SiGe film. During the exhaustion phase, the gas is removed from the system before it can accumulate and penetrate through the porous film to damage the semiconductor film. This timing control converts the porous film's permeability from a harmful feature into a controlled transport mechanism.
Solution Approach 2:
The rapid cycling through etching and exhaustion phases allows the etching gas to rush through the porous film and SiGe film in short bursts, completing the useful etching action before the gas can penetrate further to damage the semiconductor film. The quick succession of supply and exhaustion prevents gas accumulation that would otherwise exploit the porous film's permeability to cause harmful effects.
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 achieves selective etching of SiGe films while significantly reducing etching of adjacent semiconductor films by controlling the etching gas exposure time and pressure cycles.
Implementation Method 1
storing the etching gas in a reservoir provided in the gas supply path to increase an internal pressure of an interior of the reservoir
Implementation Method 2
supply the etching gas stored in the reservoir to the interior of the processing container
Data Source
AI summary
An etching method includes: exhausting a processing container in which a substrate is accommodated, the substrate including a first film, a porous film and a second film, each of the first film and the porous film being exposed from a surface of the substrate and the second film being not exposed from the surface of the substrate by being coated with the porous film; supplying, by a gas source, an etching gas having an etching property with respect to the first film and the second film to a gas supply path; storing the etching gas in a reservoir provided in the gas supply path to increase an internal pressure of the reservoir; and selectively etching the first film among the first film and the second film by opening a valve provided downstream of the reservoir to supply the etching gas stored in the reservoir into the processing container.