Silicon Nitride Etching Composition Selectivity Stability
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Solution Overview
Problem
Current silicon nitride layer etching compositions face challenges in maintaining high etch selectivity ratios and stability over time, often resulting in precipitate formation and defects during semiconductor manufacturing, especially when used repeatedly or at high temperatures.
Innovation Solution
A silicon nitride layer etching composition comprising phosphoric acid, a specific silicon compound with sulfuric acid or polyphosphoric acid groups, and water, which provides a high etch selectivity ratio and stability by preventing precipitate formation and maintaining etch rate consistency even after repeated use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional etching compositions are used, then etching process can be performed, but etch selectivity ratio decreases and precipitates form during repeated use
Solution Approach 1:
The patent changes the chemical parameters of the etching composition by incorporating specific silicon compounds (such as silicic acid, polysilicic acid, or their salts) in controlled concentrations (0.01-10 wt%) within phosphoric acid-based etching solutions. This parameter modification maintains high etch selectivity ratios (SiNx/SiO2 > 10:1) even after repeated use, preventing the degradation that occurs in conventional compositions.
Solution Approach 2:
The patent creates a composite etching composition by combining phosphoric acid with specific silicon compounds (silicic acid, polysilicic acid, or their salts). This composite formulation synergistically maintains etch selectivity and prevents precipitate formation during repeated use, solving both the selectivity ratio degradation and stability issues of conventional single-component etchants.
2Manufacturing precision
If etching treatment time is increased, then more complete etching is achieved, but etch rate and selectivity ratio change significantly
Solution Approach 1:
The patent modifies the chemical composition parameters by adding silicon compounds to phosphoric acid, creating an etching solution that maintains consistent etch rates and selectivity ratios across extended treatment times. This compositional adjustment ensures predictable etching performance whether the substrate is treated for short or extended periods.
3Productivity
If conventional etching compositions are used at high temperatures, then etching speed increases, but precipitates form and defects increase
Solution Approach 1:
The patent converts the potentially harmful effect of high temperature (which causes precipitate formation in conventional etchants) into a beneficial effect by using silicon compound-containing compositions. These compositions maintain solution stability at elevated temperatures (80-150°C), allowing high-temperature etching to proceed at increased speeds without generating precipitates or defects.
Solution Approach 2:
The composite etching composition of phosphoric acid and silicon compounds provides thermal stability that prevents precipitate formation during high-temperature processing, enabling faster etching rates without the harmful side effects that plague conventional single-component etchants.
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 effectively etches silicon nitride layers with high selectivity and stability, minimizing defects and maintaining process efficiency throughout extended use, including at high temperatures, by suppressing precipitate generation and maintaining consistent etch rates and selectivity ratios.
Implementation Method 1
A silicon nitride layer etching composition comprising phosphoric acid, a silicon compound, and water
Data Source
AI summary
Provided are a silicon nitride layer etching composition, and more specifically, a silicon nitride layer etching composition, capable of etching the silicon nitride layer at a high selectivity ratio relative to a silicon oxide layer by comprising a polysilicon compound in the etching composition, an etching method of a silicon nitride layer using the same, and a method of manufacturing a semiconductor device.