Reservoir-Pulsed Etching for Selective Film Removal
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Solution Overview
Problem
Existing etching methods fail to selectively etch a first film on a substrate without etching a second film covered by a porous film, leading to unintended etching of the second film.
Innovation Solution
An etching method involving a reservoir to store etching gas under pressure, followed by rapid release into a processing container, combined with controlled valve operations to minimize exposure of the second film to the etching gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If etching gas is supplied continuously to etch the first film, then the etching of the first film is efficient, but the second 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 first film, (2) stopping gas supply and exhausting the container, (3) repeating the process. This periodic operation allows the porous film to recover its blocking function between cycles, preventing harmful etching of the second film while maintaining efficient etching of the first film over time
Solution Approach 2:
The patent applies preliminary action by performing exhaustive evacuation of the processing container immediately after each etching cycle before the next cycle begins. This preliminary exhaustion removes residual etching gas from the container and porous film, preparing the system to prevent unwanted etching in the subsequent cycle while ensuring the first film etching can proceed efficiently
2Manufacturing precision
If the etching gas supply time is extended to complete etching of the first film, then the etching depth increases, but the etching gas penetrates the porous film and etches the second film
Solution Approach 1:
The periodic cycling of etching gas supply and exhaustion allows controlled penetration during brief intervals while preventing cumulative damage. Each short etching pulse achieves incremental etching depth, and the subsequent exhaustion period allows the porous film to clear accumulated gas, maintaining precision while preventing harmful penetration effects
Solution Approach 2:
The patent applies skipping by using brief, intense etching gas pulses rather than prolonged low-intensity exposure. Each short supply interval rushes through the necessary etching action quickly, achieving the required depth increment before the gas can significantly penetrate the porous film and reach the second film
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 effectively suppresses etching of the second film while achieving selective etching of the first film, maintaining control over the etching process.
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
opening a valve provided downstream of the reservoir in the gas supply path to supply the etching gas stored in the reservoir to the interior of the processing container
Implementation Method 3
selectively etching the first film among the first film and the second film by opening a valve provided downstream of the reservoir in the gas supply path to supply the etching gas stored in the reservoir to the interior of the processing container
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
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.