Cryogenic Plasma Etching for Silicon Dioxide and Nitride Films
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Concurrent etching of multi-layer and single-layer films of silicon dioxide and silicon nitride in semiconductor manufacturing is inefficient due to differences in etching rates, leading to prolonged processing times and reduced productivity, and requires effective temperature control to prevent substrate heating during plasma etching.
Innovation Solution
An etching method using a cryogenic environment with a combination of high-frequency power supplies to generate plasma from hydrogen and fluorine-containing gases, employing intermittent etching cycles with specific frequency and duty ratios to equalize etching rates and maintain low substrate temperatures, thereby reducing heat input and improving processing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional plasma etching is used to etch multi-layer and single-layer films concurrently, then the etching process can be performed, but the processing time becomes long and productivity is reduced due to different etching rates
Solution Approach 1:
The patent changes the physical state parameter by introducing a cryogenic environment (−35°C or lower) to equalize the etching rates of multi-layer and single-layer films. This temperature parameter change allows both film types to be etched at comparable speeds, resolving the contradiction between productivity and etching uniformity.
Solution Approach 2:
The patent employs periodic action through intermittent plasma generation, where plasma is generated for a first period followed by a second period without plasma generation. This periodic cycling allows controlled etching that maintains rate uniformity across different film types while improving overall processing efficiency.
2Productivity
If plasma etching is performed continuously, then etching can proceed without interruption, but substrate temperature increases due to heat input from plasma
Solution Approach 1:
The patent applies periodic action by interrupting plasma generation in cycles (first period with plasma, second period without plasma). This periodic operation allows the substrate to cool down during non-plasma periods, preventing excessive temperature accumulation while maintaining etching progress during plasma periods.
Solution Approach 2:
The patent implements preliminary cooling action by maintaining the substrate in a cryogenic environment (−35°C or lower) before and during the etching process. This preliminary temperature control prepares the substrate to withstand plasma heat input without excessive temperature rise, enabling more continuous etching operation.
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 equalizes etching rates of multi-layer and single-layer films, reduces substrate temperature, and enhances productivity by minimizing heat input and maintaining low temperatures, thus improving the efficiency and uniformity of the etching process.
Implementation Method 1
causing the first high-frequency power supply to output a first high-frequency power with a first frequency and causing the second high-frequency power supply to output a second high-frequency power with a second frequency lower than the first frequency in a cryogenic environment where the temperature of a wafer is −35° C. or lower, to generate plasma from a hydrogen-containing gas and a fluorine-containing gas
Implementation Method 2
etch, with the plasma, a multi-layer film of silicon dioxide and silicon nitride and a single-layer film of silicon dioxide that are formed on the wafer
Data Source
AI summary
An etching method performed by an etching apparatus includes a first process of causing a first high-frequency power supply to output a first high-frequency power with a first frequency and causing a second high-frequency power supply to output a second high-frequency power with a second frequency lower than the first frequency in a cryogenic environment where the temperature of a wafer is −35° C. or lower, to generate plasma from a hydrogen-containing gas and a fluorine-containing gas and to etch, with the plasma, a multi-layer film of silicon dioxide and silicon nitride and a single-layer film of silicon dioxide that are formed on the wafer; and a second process of stopping the output of the second high-frequency power supply. The first process and the second process are repeated multiple times, and the first process is shorter in time than the second process.