Plasma Etching of Silicon Films With Carbon Mask Protection
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Solution Overview
Problem
Existing plasma etching methods for silicon-containing films on substrates face challenges in achieving high verticality and uniformity of etching profiles, particularly in forming precise patterns with minimal mask film loss and uniform carbon-containing film formation.
Innovation Solution
A plasma processing method using a plasma processing apparatus with a substrate support and generator, employing a processing gas containing carbon, hydrogen, and fluorine, and controlling RF signals to generate a plasma that etches the silicon-containing film with hydrogen fluoride while forming a carbon-containing film on the mask film surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etching methods are used, then etching of silicon-containing film can be performed, but the etching profile verticality and uniformity are insufficient
Solution Approach 1:
A carbon-containing protective film is formed as an intermediary layer on the mask film surface. This protective film acts as a mediator that protects the mask film from direct contact with the etching plasma, preventing mask film loss while enabling improved etching profile control. The protective film is formed by introducing a carbon-containing gas (such as methane or ethane) into the plasma environment, where carbon species deposit on the mask film surface.
Solution Approach 2:
The etching process utilizes parameter changes by controlling the ratio of carbon-containing gas flow rate to total gas flow rate, and by adjusting plasma power and pressure parameters. These parameter changes enable dynamic control of the protective film formation and etching rate, achieving both vertical profile etching and mask film protection. The carbon-containing gas flow rate is specifically controlled to be 5-50 sccm to optimize protective film formation.
2Manufacturing precision
If etching is performed with high selectivity, then silicon-containing film etching is improved, but mask film loss increases
Solution Approach 1:
The carbon-containing protective film serves as a protective intermediary between the aggressive etching plasma and the mask film. This intermediary layer allows the use of high-selectivity etching conditions (such as CF4-based plasma with high fluorine content) without direct damage to the mask film, as the protective film absorbs the harmful effects while being replenished continuously during the etching process.
Solution Approach 2:
The protective carbon-containing film is formed on the mask film surface before the main etching process begins. This preliminary action prepares the mask film for subsequent high-selectivity etching by pre-establishing a protective barrier. The protective film formation is performed by introducing carbon-containing gas at controlled flow rates for a specific time period prior to introducing the main etching gas.
3Reliability
If conventional plasma conditions are used, then processing can be performed, but carbon-containing film formation on mask film is insufficient
Solution Approach 1:
The process optimizes the balance between protective film formation and etching rate by controlling carbon-containing gas flow rate parameters. By setting the carbon-containing gas flow rate to 5-50 sccm (specifically 10-30 sccm in preferred embodiments), sufficient carbon species are available to form a protective film without excessively reducing the etching rate. The plasma power is maintained at 100-500 W and pressure at 10-100 mTorr to balance film formation and etching efficiency.
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 achieves high verticality and improved uniformity in etching profiles, maintaining mask film integrity and enhancing the selection ratio of silicon-containing film etching, with a carbon-containing film protecting the mask film.
Implementation Method 1
generating a plasma from the processing gas by supplying a source RF signal to the plasma generator
Implementation Method 2
the silicon-containing film is etched by at least hydrogen fluoride generated from the processing gas
Implementation Method 3
supplying a bias RF signal to the substrate support
Implementation Method 4
forming a carbon-containing film on at least a part of a surface of the mask film
Data Source
AI summary
A plasma processing method includes: providing a substrate including a silicon-containing film and a mask film having an opening pattern, on a substrate support; and etching the silicon-containing film using the mask film as a mask, with a plasma generated by a plasma generator provided in the chamber. The etching includes: supplying a processing gas containing one or more gases including carbon, hydrogen, and fluorine into the chamber; generating a plasma from the processing gas by supplying a source RF signal to the plasma generator; and supplying a bias RF signal to the substrate support unit. In the etching, the silicon-containing film is etched by at least hydrogen fluoride generated from the processing gas, while forming a carbon-containing film on at least a part of a surface of the mask film.