Plasma Etching of Silicon Nitride Films With Chlorine Byproduct Control
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Solution Overview
Problem
Existing etching methods for silicon-containing films face challenges in achieving precise control over etching rates and preventing shape abnormalities, such as tapered bottoms and twisting, due to the difficulty in managing the reaction by-products like ammonium silicofluoride, which adhere to the etched recesses and affect the etching process.
Innovation Solution
An etching method involving a plasma processing system that supplies a process gas mixture containing hydrogen fluoride, a phosphorus fluoride gas, and a chlorine-containing gas, where the chlorine-containing gas flow rate is between 1.5 to 5 volume % of the total flow, generating a plasma that effectively etches silicon-containing films while suppressing shape abnormalities by breaking down reaction by-products and maintaining etching rate and selection ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used to etch silicon-containing films, then etching can be performed, but shape abnormalities such as tapered bottoms and twisting occur due to adherent reaction by-products
Solution Approach 1:
The patent converts the harmful reaction by-products (ammonium silicofluoride) into beneficial volatile compounds by introducing chlorine-containing gas. The chlorine reacts with the adherent by-products to form volatile silicon chloride compounds that can be easily removed, thereby eliminating the shape abnormalities caused by by-product adhesion while maintaining efficient etching
Solution Approach 2:
The patent changes the chemical composition parameters of the etching gas by specifying that the chlorine-containing gas should constitute 1.5 volume% or more of the total process gas flow. This parameter change enables the chlorine to effectively react with and remove reaction by-products, preventing shape abnormalities while maintaining high etching rates
2Productivity
If etching is performed with high etching rates, then productivity is improved, but control over etching shape and prevention of abnormalities becomes difficult
Solution Approach 1:
The patent simultaneously achieves high productivity and shape control by converting harmful by-products into volatile compounds through chlorine-containing gas. This allows rapid etching to proceed without the accumulation of adherent by-products that would otherwise cause shape abnormalities, thus resolving the contradiction between speed and precision
Solution Approach 2:
By optimizing the chlorine-containing gas flow rate parameter to be 1.5 volume% or more of the total process gas, the patent achieves a balance where high etching rates are maintained while by-product removal is sufficient to prevent shape abnormalities, thereby simultaneously improving productivity and manufacturing precision
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 suppresses etching shape abnormalities and maintains high etching rates and selection ratios by using the chlorine-containing gas to break down adherent by-products, ensuring precise control over the etching process.
Implementation Method 1
generating a plasma from the process gas to etch the silicon-containing film
Implementation Method 2
the process gas containing a hydrogen fluoride gas and a chlorine-containing gas
Data Source
AI summary
The purpose of this disclosure is to provide an etching method. This method includes: (a) providing a substrate on a substrate support in a chamber, the substrate including a silicon-containing film and a mask on the silicon-containing film, the silicon-containing film including silicon and nitrogen; (b) supplying a process gas to the chamber, the process gas containing a hydrogen fluoride gas and a chlorine-containing gas, where a flow rate of the chlorine-containing gas is 1.5 volume % or more of a total flow of the process gas excluding an inert gas; and (c) generating a plasma from the process gas to etch the silicon-containing film.