Silicon Nitride Etching Sequence for Oxide Pattern Shape Control
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Solution Overview
Problem
Existing substrate processing methods face challenges in maintaining a desired pattern shape of silicon oxide films when etching highly stacked silicon nitride and silicon oxide films due to silicon oxide deposition during the etching process, which disrupts the intended pattern formation.
Innovation Solution
A method involving a two-step etching process is employed, first etching the silicon nitride film with a phosphoric acid solution adjusted for silicon concentration, followed by a pattern shape processing step to remove deposited silicon oxide, and a second etching step to complete the process, ensuring minimal silicon oxide deposition on the silicon oxide film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single-step etching process is used to etch highly stacked silicon nitride and silicon oxide films, then the etching process is simple and fast, but silicon oxide deposition occurs during etching which disrupts the intended pattern formation
Solution Approach 1:
The etching process is divided into multiple sequential steps: a first etching step to etch the silicon nitride film, followed by a processing step to remove deposited silicon oxide, and then a second etching step to complete the etching of silicon nitride and etch the silicon oxide film. This segmentation allows each step to be optimized independently, preventing silicon oxide deposition from disrupting pattern formation while maintaining overall process efficiency
Solution Approach 2:
The processing step is inserted between the first and second etching steps to preliminarily remove deposited silicon oxide before the final etching is completed. This preliminary action prevents the accumulation of silicon oxide that would otherwise disrupt the intended pattern formation in subsequent etching steps
2Speed
If phosphoric acid solution with high silicon concentration is used for etching, then the etching rate increases, but silicon oxide deposition on silicon oxide film increases
Solution Approach 1:
The etching process uses periodic action by alternating between etching steps using phosphoric acid solution and processing steps using pattern shape processing liquid. This periodic alternation allows the system to achieve high etching rates when needed while periodically removing silicon oxide deposition, preventing it from disrupting pattern formation
Solution Approach 2:
The processing step converts the harmful effect of silicon oxide deposition into a beneficial outcome by selectively removing the deposited silicon oxide using pattern shape processing liquid, thereby restoring the intended pattern shape and actually improving the overall pattern formation quality
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 maintains a good pattern shape of silicon oxide films even on substrates with highly stacked silicon nitride and silicon oxide layers, preventing silicon oxide deposition and ensuring precise pattern formation.
Implementation Method 1
In a first etching step, a substrate on which a silicon oxide film and a silicon nitride film are formed is etched with an etching liquid
Implementation Method 2
a pattern formed in the silicon oxide film on the substrate is processed with a pattern shape processing liquid
Data Source
AI summary
An etching method includes a first etching step, a processing step, and a second etching step. The first etching step is performed to etch a substrate on which a silicon oxide film and a silicon nitride film are formed with an etching liquid. The processing step is performed to process a pattern in the silicon oxide film on the substrate with a pattern shape processing liquid after the first etching step. The second etching step is performed to etch the substrate with the etching liquid after the processing step.