Two-Stage Plasma Etching for Silicon Film Selectivity
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Solution Overview
Problem
Existing etching methods face challenges in achieving high etch selectivity when processing silicon-containing films using masks made of amorphous carbon or organic polymers.
Innovation Solution
An etching method involving two stages: initial etching with hydrogen fluoride gas to form a recess without exposing the underlying film, followed by a second etching stage using a different process gas and conditions to further etch the silicon-containing film, including controlling temperature and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single etching process is used to etch the silicon-containing film, then the etching rate is maintained, but the etch selectivity deteriorates causing the underlying film to be exposed
Solution Approach 1:
The etching process is divided into two distinct stages: a first etching process that etches the silicon-containing film without exposing the underlying film, and a second etching process that continues etching under different conditions. This segmentation allows optimization of etch selectivity at each stage, preventing premature exposure of the underlying film while maintaining overall etching efficiency.
Solution Approach 2:
The etching process dynamically adjusts parameters between two stages: the first etching process uses specific plasma conditions to achieve high selectivity, and when a predetermined condition is met (such as when the etching depth reaches a threshold), the process transitions to a second etching process with different parameters. This dynamic adjustment maintains optimal etch selectivity throughout the entire etching sequence.
2Manufacturing precision
If the etching continues until the underlying film is fully exposed, then the etching completeness is improved, but the manufacturing precision deteriorates due to loss of selectivity
Solution Approach 1:
The etching process incorporates feedback control by monitoring predetermined conditions during the first etching process. When the monitoring indicates that continuing the first etching process would expose the underlying film, the system automatically transitions to the second etching process. This feedback mechanism ensures the silicon-containing film is completely etched while protecting the underlying film from damage.
Solution Approach 2:
The method performs preliminary etching action in the first etching process to remove the majority of the silicon-containing film while maintaining high selectivity. By preparing the structure in advance and stopping before the underlying film is exposed, the second etching process can then complete the removal with appropriate parameter adjustments, ensuring complete etching without compromising the underlying film.
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
Improves etch selectivity by selectively etching the silicon-containing film without exposing the underlying film, enhancing precision and control in semiconductor manufacturing.
Implementation Method 1
etching the silicon-containing film to form a recess with first plasma generated from a first process gas containing a hydrogen fluoride gas
Implementation Method 2
etching the silicon-containing film with first plasma generated from a first process gas containing a hydrogen fluoride gas
Data Source
AI summary
A technique improves etch selectivity. An etching includes (a) providing, in a chamber, a substrate including an underlying film and a silicon-containing film on the underlying film, (b) etching the silicon-containing film to form a recess with first plasma generated from a first process gas containing a hydrogen fluoride gas until before the underlying film is exposed at the recess or until the underlying film is partly exposed at the recess, and (c) further etching the silicon-containing film at the recess under a condition different from a condition of (b).