WF6 Plasma Etching of Silicon Oxide Recesses With Periodic DC Bias
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Solution Overview
Problem
Plasma etching methods for silicon-containing films face challenges in maintaining the shape integrity of recesses, particularly due to abnormal shape distortions and uneven etching rates, which existing techniques struggle to address effectively.
Innovation Solution
An etching method involving a substrate with a silicon oxide film, using a processing gas mixture of tungsten hexafluoride, carbon and fluorine-containing gases, and oxygen, with periodic application of negative DC voltage to the substrate support, allowing for selective substitution of silicon atoms with tungsten and controlled etching to suppress shape abnormalities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etching is used on silicon-containing films, then etching can be performed, but abnormal shape distortion and uneven etching rates occur
Solution Approach 1:
The patent applies periodic reversal of DC voltage polarity during plasma etching. The voltage switching between positive and negative polarity creates periodic action that prevents abnormal shape distortion and ensures uniform etching rates across the substrate surface
Solution Approach 2:
The patent changes the electrical parameter (DC voltage polarity) dynamically during the etching process. By reversing the voltage polarity periodically, the etching conditions are modified to maintain shape consistency and prevent deposition abnormalities
2Productivity
If high etching rate is achieved, then productivity improves, but shape abnormality and bowing increase
Solution Approach 1:
The periodic voltage reversal allows the process to maintain high etching rates while preventing film bowing. During each voltage cycle, the plasma conditions are optimized for etching, while the polarity switch prevents excessive deposition and shape distortion that would occur with continuous single-polarity etching
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 method achieves a high etching rate with reduced bowing of the silicon-containing film, ensuring precise recess formation and suppressing excessive deposition, thereby improving the shape consistency and efficiency of the etching process.
Implementation Method 1
step (c) of generating plasma from the processing gas to etch the silicon-containing film
Implementation Method 2
Step (c) includes periodically applying a negative DC voltage to the substrate support
Data Source
AI summary
An etching method includes: (a) preparing a substrate including a silicon-containing film including a silicon oxide film and placed on a substrate support provided in a chamber; (b) supplying a processing gas containing a tungsten hexafluoride gas, a gas containing carbon and fluorine, and an oxygen-containing gas into the chamber; and (c) generating plasma from the processing gas to etch the silicon-containing film. (c) includes periodically applying a negative DC voltage to the substrate support.