Low-Temperature Plasma Etching of Silicon Oxide and Nitride Films
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Solution Overview
Problem
Existing methods for etching silicon oxide and silicon nitride films on substrates face challenges in achieving efficient and precise control over the etching process, particularly in maintaining the integrity of underlying films and mask films during plasma processing.
Innovation Solution
A plasma processing method involving the use of distinct processing gases and temperature control to generate plasmas at 0°C or lower, combined with specific gas compositions and bias signals, to etch silicon nitride and silicon oxide films separately, ensuring precise etching and improved adsorption of HF species.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional plasma processing is used to etch silicon oxide and silicon nitride films, then the etching process can be performed, but the etching rate is insufficient and film integrity cannot be maintained
Solution Approach 1:
The patent applies parameter changes by controlling the substrate temperature to 0°C or lower during plasma etching. This temperature parameter modification enables the use of HF-based processing gases to achieve both high etching rates and excellent film integrity, resolving the contradiction between productivity and reliability in the etching process.
Solution Approach 2:
The patent employs local quality by creating different plasma conditions for etching silicon oxide versus silicon nitride films. By adjusting gas composition and plasma parameters specifically tailored to each film type while maintaining low substrate temperature, the process achieves selective etching with high rates and preserved film quality.
2Productivity
If higher temperature plasma processing is used to increase etching rate, then productivity improves, but adsorption of HF species decreases and film damage increases
Solution Approach 1:
The patent reverses the conventional approach by lowering the substrate temperature to 0°C or lower instead of increasing it. This parameter change enhances the adsorption precision of HF species on the film surface, enabling high etching rates without compromising manufacturing precision or causing film damage.
Solution Approach 2:
The patent converts the typically harmful effect of low temperature (reduced reaction kinetics) into a benefit by enhancing HF species adsorption. This allows the process to achieve both high productivity through efficient etching and high precision through improved adsorption, turning what would normally be a disadvantage into an advantage.
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 enhances etching rates and maintains film integrity by promoting the adsorption of HF species at low temperatures, thereby improving the precision and efficiency of the etching process.
Implementation Method 1
generating a first plasma from a first processing gas including HF gas, CxFy gas (x and y are integers of 1 or more), and an oxygen-containing gas to etch the silicon nitride film
Implementation Method 2
etch the silicon nitride film; and (c) generating a second plasma from a second processing gas including HF gas, CvFw gas (v and w are integers of 1 or more), and an oxygen-containing gas to etch the silicon oxide film
Implementation Method 3
a temperature of the substrate support is set to 0° C. or lower... promoting the adsorption of HF species at low temperatures
Data Source
AI summary
A plasma processing method includes: (a) providing a substrate having an etching target film including a silicon oxide film and a silicon nitride film, and a mask film defining an opening over the etching target film, on a substrate support in a chamber of a plasma processing apparatus; (b) generating a first plasma from a first processing gas including HF gas, CxFy gas (x and y are integers of 1 or more) or CsHtFu gas (s, t, and u are integers of 1 or more), and an oxygen-containing gas to etch the silicon nitride film; and (c) generating a second plasma from a second processing gas including HF gas, CvFw gas (v and w are integers of 1 or more), and an oxygen-containing gas to etch the silicon oxide film. In (b) and (c), a temperature of the substrate support is set to 0° C. or lower.