Silicon Nitride Etching Selectivity via Cyclic Nitrogen Compounds
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Solution Overview
Problem
Existing etching methods for silicon nitride layers in semiconductor manufacturing face limitations in increasing silicon nitride layer-to-silicon oxide layer etching selectivity, particularly at high temperatures, and require costly storage and transportation processes to maintain selectivity.
Innovation Solution
An etching composition comprising an inorganic acid, acid-modified silica or silicic acid, and a cyclic compound with four or more nitrogen atoms, such as tetrazole, which enhances etching selectivity and stability, allowing retention of high selectivity even after storage at ambient temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a phosphoric acid solution is used to etch silicon nitride layer, then the etching process can be performed, but the silicon nitride layer-to-silicon oxide layer etching selectivity cannot be increased sufficiently
Solution Approach 1:
The patent uses a composite etching composition containing phosphoric acid (inorganic acid), silane compound, and cyclic nitrogen compound together. This composite formulation achieves both high etching selectivity between silicon nitride and silicon oxide layers while maintaining reliable etching performance, resolving the contradiction between selectivity improvement and performance reliability.
Solution Approach 2:
The patent modifies the chemical composition parameters of the etching solution by adding specific concentrations of silane compound (0.001-10 wt%) and cyclic nitrogen compound (0.0001-10 wt%) to the phosphoric acid base. These parameter changes enable the solution to achieve enhanced selectivity while maintaining stable etching performance across different processing conditions.
2Manufacturing precision
If high temperature storage is used to maintain etching selectivity, then selectivity can be preserved, but storage and transportation costs increase
Solution Approach 1:
The etching composition is formulated to be self-stabilizing at ambient temperature through the synergistic interaction of phosphoric acid, silane compound, and cyclic nitrogen compound. This self-service property eliminates the need for external high-temperature storage conditions, allowing the composition to maintain its etching selectivity naturally under normal storage conditions without additional energy input.
Solution Approach 2:
The patent changes the chemical stability parameters of the etching solution by incorporating silane and cyclic nitrogen compounds that prevent decomposition and maintain selectivity at ambient temperature. This parameter modification allows the solution to be stored and transported under normal conditions without requiring high-temperature environments, thereby reducing energy costs.
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 composition significantly increases silicon nitride layer-to-silicon oxide layer etching selectivity at high temperatures and maintains this selectivity after storage at room temperature, eliminating the need for high-temperature storage and transportation equipment and costs.
Implementation Method 1
An etching method may use a phosphoric acid solution heated to high temperature to remove a silicon nitride layer pattern formed on a substrate
Implementation Method 2
Addition of a silane compound to the phosphoric acid solution may be considered to increase the etching selectivity
Implementation Method 3
the etching composition including an inorganic acid or a salt thereof; a solvent; an acid-modified silica or an acid-modified silicic acid; and a cyclic compound containing four or more nitrogen atoms
Data Source
AI summary
An etching composition for silicon nitride layers and a method of etching a silicon nitride layer using the composition, the etching composition including an inorganic acid or a salt thereof; a solvent; an acid-modified silica or an acid-modified silicic acid; and a cyclic compound containing four or more nitrogen atoms.