Selective Etching Using Carbon Monoxide Plasma Deposits
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing etching methods struggle to selectively etch a second region of a substrate, such as silicon oxide, while protecting a first region, typically silicon nitride, as existing techniques often result in non-selective deposition of fluorocarbon films that can block the recess opening.
Innovation Solution
An etching method involving the use of carbon monoxide gas to form a selective deposit on the first region, preventing its deposition on the second region, allowing for the selective etching of the second region using plasma-generated ions, with the process potentially involving alternating cycles of deposition and etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluorocarbon is deposited on both first and second regions to protect the first region, then the first region is protected, but the recess opening becomes blocked
Solution Approach 1:
The patent applies local quality by making the deposit formation selective to specific regions. The first deposit is formed preferentially on the first region (silicon nitride) while avoiding the second region (silicon oxide), achieving protective coverage only where needed without blocking the recess opening. This is accomplished through selective plasma deposition processes that respond to material differences between regions.
2Reliability
If fluorocarbon is used to protect the first region, then selective protection is achieved, but etching selectivity between first and second regions is reduced
Solution Approach 1:
The patent segments the protective deposit into two distinct types: a first deposit formed from carbon-containing plasma that preferentially covers the first region, and a second deposit formed from fluorocarbon-containing plasma that covers the second region. This segmentation allows each deposit type to serve its specific function without interfering with the other, maintaining both protection and etching selectivity.
Solution Approach 2:
The patent employs composite materials by combining two different deposit types with distinct chemical compositions. The first deposit (carbon-based) and second deposit (fluorocarbon-based) form a composite protective structure that leverages the complementary properties of each material: the carbon-based deposit provides initial selective protection while the fluorocarbon deposit enables selective etching of the second region.
3Manufacturing precision
If alternating cycles of deposition and etching are performed, then etching precision is improved, but process complexity increases
Solution Approach 1:
The patent implements periodic action through alternating cycles of deposition and etching steps. The process repeatedly performs: forming first deposit from carbon-containing plasma, etching second region, forming second deposit from fluorocarbon-containing plasma, and etching second region again. This periodic repetition refines the etching precision by progressively removing material while maintaining protective coverage, achieving high aspect ratio trenches with vertical walls.
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
This method effectively etches the second region while maintaining protection of the first region, reducing the risk of recess opening blockage and ensuring high verticality of the deposit on the first region, thus enhancing the etching process's precision and effectiveness.
Implementation Method 1
forming a deposit preferentially on the first region with first plasma generated from a first process gas containing a carbon monoxide gas
Implementation Method 2
etching the second region with plasma-generated ions
Data Source
AI summary
An etching method includes (a) providing a substrate. The substrate includes a first region and a second region. The second region contains silicon oxide, and the first region contains a material different from a material for the second region. The etching method further includes (b) forming a deposit preferentially on the first region with first plasma generated from a first process gas containing a carbon monoxide gas. The etching method further includes (c) etching the second region.