Etching Method for Mask Shape Abnormality Suppression
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Solution Overview
Problem
In self-aligned multi-patterning (SAMP) techniques, the shape of the mask formed on a substrate can become abnormal due to etching, leading to 'leading end thinning, which impairs the mask's function during the etching process.
Innovation Solution
An etching method involving a substrate with core members and a spacer film, where a protective film is formed on the spacer film using a first gas and left on the side surfaces of core members during plasma etching, repeating the process to maintain the mask's shape and prevent abnormality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma etching is performed on the spacer film to expose core members, then the etching process can proceed, but the shoulder portions of the spacer film become abnormal in shape due to direct plasma exposure
Solution Approach 1:
A protective film is introduced as an intermediary layer between the plasma and the spacer film. This protective film absorbs the direct plasma exposure, preventing the shoulder portions of the spacer film from becoming abnormal in shape while still allowing the etching process to proceed effectively.
Solution Approach 2:
The protective film is formed on the spacer film before the plasma etching process begins. This preliminary protective action ensures that when plasma is applied, the shoulder portions are already shielded, preventing shape abnormalities before they can occur during the etching process.
2Ease of manufacture
If the spacer film is directly exposed to plasma for etching, then etching can be performed, but leading end thinning occurs which impairs mask function
Solution Approach 1:
The protective film serves as a mediator that allows plasma etching to proceed while preventing the harmful direct interaction between plasma and the spacer film's shoulder portions, thereby preventing leading end thinning and maintaining mask function reliability.
Solution Approach 2:
The protective film provides beforehand cushioning by being positioned in advance to absorb and distribute the plasma energy, preventing the concentration of energy at the shoulder portions that would cause leading end thinning and mask function impairment.
3Shape
If repeated cycles of protective film formation and etching are performed, then mask shape accuracy is maintained, but process time increases
Solution Approach 1:
The process uses periodic cycles of protective film formation followed by controlled etching. This periodic approach allows the protective film to be replenished at intervals, maintaining mask shape accuracy through repeated short cycles rather than requiring one long continuous process, thereby reducing overall time loss.
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 mask shape abnormalities, maintaining a rectangular cross-sectional shape and improving mask formation throughput by protecting the spacer film's shoulder portions, ensuring precise pattern formation.
Implementation Method 1
forming a second film on a surface of the first film by a first gas
Implementation Method 2
etching the first film by plasma of a second gas
Data Source
AI summary
An etching method includes preparing a substrate having a processing target film, multiple core members formed on the processing target film, and a first film covering the multiple core members and the processing target film exposed between the multiple core members; forming a second film on a surface of the first film by a first gas; etching the first film by plasma of a second gas while allowing the second film to be left on a portion of the first film corresponding to a side surface of each core member; and repeating the forming of the second film and the etching of the first film.