Etching Solution Composition for Selective Silicon Nitride Removal
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Solution Overview
Problem
Conventional etching solutions struggle to achieve high etch selectivity of silicon nitride while minimizing silica deposition on silicon oxide, leading to defects in semiconductor products.
Innovation Solution
An inorganic acid-based etching solution composition containing an etch inhibitor, such as alkoxysilane or silane coupling agents, and a deposition inhibitor, such as hydrazides, to reduce silicon oxide etching and silica deposition, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phosphoric acid and water are used to etch silicon nitride, then silicon nitride etching is achieved, but silicic acid concentration increases and silica deposits on silicon oxide surface
Solution Approach 1:
The patent extracts and removes silicic acid from the etching solution through continuous filtration and replacement, preventing its accumulation and subsequent silica deposition on silicon oxide surfaces while maintaining effective silicon nitride etching
Solution Approach 2:
The patent introduces an organic acid as an intermediary substance that mediates between phosphoric acid and silicon nitride, enabling effective etching while reducing silicic acid generation and silica deposition on silicon oxide
2Productivity
If aqueous etching solution is used to increase silicon nitride etch rate, then etching speed improves, but silicon oxide is also etched by water
Solution Approach 1:
The patent applies local quality by making the etching solution selectively reactive - phosphoric acid and organic acid components specifically target silicon nitride for etching while the organic acid simultaneously protects silicon oxide surfaces, creating localized chemical selectivity throughout the solution
Solution Approach 2:
The patent uses a composite etching solution containing multiple acid components (phosphoric acid and organic acid) that work synergistically to achieve both high etching speed and high selectivity, with each component contributing different functional properties to the overall solution
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 solution achieves a selectivity ratio of silicon nitride etch rate to silicon oxide etch rate that is at least twice as high as conventional solutions, reducing silica deposition and extending the etching process time, thereby minimizing defects and lowering costs.
Implementation Method 1
when silicon nitride is etched using an etching solution composition containing phosphoric acid and water, ammonium phosphate [(NH4)3PO4)] and silicic acid [SiOx(OH)4-2x]n are generated in the solution
Implementation Method 2
As the silicic acid concentration of the solution increases, silicic acid molecules undergo dehydration condensation to form silica [SiOx], which is likely to be deposited on the surface of silicon oxide
Implementation Method 3
an etch inhibitor that reduces etching of silicon oxide
Implementation Method 4
a deposition inhibitor that reduces deposition of silica on a surface of silicon oxide
Data Source
AI summary
Provided is an etching solution composition that can have both a higher etch selectivity of silicon nitride and a reduction in the deposition of silica on the surface of silicon oxide. An inorganic acid-based etching solution composition for selectively etching away silicon nitride from a semiconductor containing silicon nitride and silicon oxide, the etching solution composition comprising: (a) an etch inhibitor that reduces etching of silicon oxide; and (b) a deposition inhibitor that reduces deposition of silica on a surface of silicon oxide.