Silicon Etching Sidewall Oxide Protection
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Solution Overview
Problem
Existing etching methods for silicon films face challenges in achieving precise control over the etching process, particularly in regions beneath the mask, leading to skirt shape improvements but also lateral bowing due to over-etching, which is difficult to manage without compromising the shape.
Innovation Solution
An etching method involving a plasma treatment process that modifies the silicon film surface into an oxide layer using a gas containing oxygen, hydrogen, and a second halogen atom, forming a protective sidewall oxide layer to prevent lateral etching, allowing for precise etching control and deeper penetration without abnormal shape formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If etching depth is increased to achieve deeper penetration, then deeper etching is achieved, but abnormal shape formation occurs
Solution Approach 1:
The oxide layer is formed in advance on the silicon film surface before deep etching is performed. This protective oxide layer prevents abnormal shape formation even when etching to greater depths, as it controls the etching front and prevents lateral bowing that would otherwise occur during deep etching processes.
2Manufacturing precision
If mask pattern is used to define etching regions, then precise pattern transfer is achieved, but skirt shape deterioration occurs in regions beneath the mask
Solution Approach 1:
The oxide layer is formed on the silicon film surface before etching, including in regions beneath the mask. During the etching process, this oxide layer protects the silicon in these regions from excessive lateral etching, preventing skirt shape deterioration while allowing the mask pattern to be precisely transferred to the silicon 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
The method enables precise etching of silicon films as designed, improving the skirt shape while preventing lateral bowing by forming a high-purity, thick oxide layer that acts as a protective sidewall, allowing for deeper etching without compromising the shape.
Implementation Method 1
etching the silicon film using the mask by plasma of a gas containing a first halogen atom
Implementation Method 2
etching the silicon film using the mask by plasma of a gas containing a first halogen atom
Implementation Method 3
modifying a surface of the silicon film into an oxide layer by plasma of a gas containing an oxygen atom, a hydrogen atom, and a second halogen atom
Implementation Method 4
modifying a surface of the silicon film into an oxide layer by plasma of a gas containing an oxygen atom, a hydrogen atom, and a second halogen atom
Implementation Method 5
etching the oxide layer to remove the second region while leaving the first region
Implementation Method 6
etching the oxide layer to remove the second region while leaving the first region
Data Source
AI summary
According to an exemplary embodiment, a method includes preparing a workpiece including a silicon film and a mask provided on the silicon film, etching the silicon film using the mask by plasma of a gas containing a first halogen atom, modifying a surface of the silicon film into an oxide layer by plasma of a gas containing an oxygen atom, a hydrogen atom, and a second halogen atom, the oxide layer including a first region extending along a side wall surface of the mask and a second region extending on the silicon film, etching the oxide layer to remove the second region while leaving the first region, and etching the silicon film using the mask and the oxide layer including the first region by plasma of a gas containing a third halogen atom.