Dynamic Temperature Control for Silicon Nitride Etching
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Solution Overview
Problem
During the etching of silicon nitride films on substrates, the concentration of silicon in the phosphoric acid processing liquid increases, leading to precipitation of silicon oxide on silicon oxide films, which affects the etching process.
Innovation Solution
A substrate processing apparatus with a temperature adjustment unit and controller that lowers the temperature of the phosphoric acid processing liquid as etching proceeds, along with adjustments to phosphoric acid and silicon concentrations, to prevent silicon oxide precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the temperature of the phosphoric acid processing liquid is maintained at a constant high level to ensure efficient etching of silicon nitride films, then the etching rate is improved, but silicon oxide precipitates on the substrate surface due to increased silicon concentration
Solution Approach 1:
The patent applies dynamics by transitioning from a static constant temperature process to a dynamic temperature adjustment process. The temperature is initially set high (80-90°C) to achieve fast etching, then lowered (60-70°C) when silicon concentration increases, allowing the system to adapt to changing conditions and prevent precipitation while maintaining etching efficiency
Solution Approach 2:
The patent changes the temperature parameter dynamically during the etching process. By adjusting the temperature based on the progression of etching and silicon concentration levels, the system optimizes both etching rate and precipitation prevention, demonstrating parameter changes as a solution to the technical contradiction
2Manufacturing precision
If the etching process continues for an extended period to complete the silicon nitride film removal, then the etching depth increases, but the silicon concentration in the processing liquid accumulates causing harmful precipitation
Solution Approach 1:
The patent implements feedback control by monitoring the etching process progression and silicon concentration accumulation, then adjusting the temperature accordingly. This feedback mechanism allows the system to maintain etching depth while preventing precipitation by responding to changing process conditions
Solution Approach 2:
The patent applies periodic action by changing the temperature at specific intervals during the etching process. The temperature is adjusted in stages based on process progression, creating a periodic pattern of high-temperature etching followed by lower-temperature precipitation prevention
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
This approach effectively reduces the etching rate of silicon nitride films, preventing silicon oxide precipitation and maintaining a stable etching process by controlling the temperature and concentrations of the processing liquid.
Implementation Method 1
The temperature adjustment unit is configured to adjust a temperature of the phosphoric acid processing liquid
Implementation Method 2
perform an etching processing which, among a silicon nitride film (SiN) and a silicon oxide film (SiO2) formed on a substrate, selectively etches the silicon nitride film by immersing the substrate in a phosphoric acid processing liquid
Data Source
AI summary
A substrate processing apparatus according to an embodiment includes a substrate processing tank, a temperature adjustment unit, and a controller. The substrate processing tank is configured to perform an etching processing by immersing a substrate in a phosphoric acid processing liquid therein. The temperature adjustment unit is configured to adjust the temperature of the phosphoric acid processing liquid. The controller is configured to control the temperature adjustment unit to lower the temperature of the phosphoric acid processing liquid as the etching processing proceeds.