HF-Assisted Plasma Etching of Silicon Film Stacks for Uniform Recesses
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Solution Overview
Problem
Existing etching methods face challenges in achieving uniformity and suppressing surface roughness in the recesses of film stacks with alternating silicon-containing films, leading to shape abnormalities and inefficiencies in semiconductor manufacturing.
Innovation Solution
An etching method involving a substrate with a film stack of alternating silicon-containing films, using plasma generated from a processing gas containing hydrogen fluoride to form a recess, and subsequent controlled supply of hydrogen fluoride to refine the recess dimensions, adjusting temperature and pressure conditions to optimize etching selectivity and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma etching is used to etch alternating silicon-containing films, then etching speed is improved, but surface roughness increases and shape uniformity deteriorates
Solution Approach 1:
The etching process is segmented into multiple distinct stages: a first etching process using plasma to form the recess, followed by a second etching process using hydrogen fluoride to further etch the recess. This segmentation allows each process to be optimized independently - the plasma process provides high etching speed while the hydrogen fluoride process refines the surface and ensures uniformity across different silicon-containing films.
Solution Approach 2:
Hydrogen fluoride is introduced as an intermediary substance in the second etching process to mediate between the rough plasma-etched surface and the desired smooth, uniform final shape. The hydrogen fluoride selectively etches the silicon-containing films to smooth out surface irregularities and achieve consistent dimensions across different film types.
2Device complexity
If conventional etching methods are used on alternating silicon-containing films, then process simplicity is maintained, but etching selectivity and uniformity across different films deteriorate
Solution Approach 1:
The invention changes the chemical parameters of the etching process by using different etchants for different stages - plasma for the first stage and hydrogen fluoride for the second stage. This parameter change enables selective etching of different silicon-containing films with appropriate selectivity ratios, achieving uniform recess shapes across alternating films while maintaining a relatively simple two-step process structure.
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 surface roughness and shape abnormalities, achieving uniform recess dimensions and improving the etching process efficiency by selectively etching silicon oxide and silicon nitride films, thereby enhancing semiconductor manufacturing outcomes.
Implementation Method 1
etching the film stack using plasma generated from a first processing gas to form a recess in the film stack
Implementation Method 2
supplying hydrogen fluoride to the recess in the film stack
Data Source
AI summary
An etching method includes: (a) providing a substrate having a film stack including at least two different silicon-containing films and a mask on the film stack; (b) etching the film stack using plasma generated from a first processing gas to form a recess in the film stack; and (c) supplying hydrogen fluoride to the recess in the film stack.