Semiconductor Nitride Etching With High Oxide Selectivity
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Solution Overview
Problem
Existing semiconductor etching methods require multiple steps and the use of dummy spacers to protect the substrate, which complicates the process and can cause damage to the substrate surface.
Innovation Solution
An etching method that increases the selectivity ratio of etching nitride to oxide materials by adjusting the etching process to reduce the etching rate of oxide materials, allowing for the direct removal of nitride layers without forming dummy spacers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dummy spacers are formed to protect the substrate surface during etching, then substrate damage is avoided, but the process complexity increases
Solution Approach 1:
The patent removes the dummy spacer structure from the process by achieving selective etching through chemical composition control. By adjusting the oxide layer to contain 40-80 at% silicon and the nitride layer to contain 90-99 at% nitrogen, the etching selectivity between these layers is dramatically improved, allowing direct etching of the nitride layer without requiring protective dummy spacers.
Solution Approach 2:
The patent changes the chemical composition parameters of the oxide and nitride layers to optimize etching selectivity. Specifically, controlling the silicon content in the oxide layer (40-80 at%) and nitrogen content in the nitride layer (90-99 at%) creates a significant difference in etching rates between the two materials, enabling selective removal of the nitride layer while preserving the oxide layer and substrate.
2Ease of manufacture
If existing etching liquid is used, then the etching process is simple, but the etching selectivity ratio is insufficient
Solution Approach 1:
The patent modifies the chemical composition parameters of the material layers to work effectively with existing etching liquids. By optimizing the silicon content in the oxide layer (40-80 at%) and nitrogen content in the nitride layer (90-99 at%), the patent achieves an etching selectivity ratio greater than 30:1 using conventional etching chemicals, thus maintaining process simplicity while dramatically improving selectivity.
3Manufacturing precision
If the etching rate of oxide material is reduced, then the etching selectivity ratio increases, but the etching process time may increase
Solution Approach 1:
The patent optimizes the silicon content in the oxide layer (40-80 at%) to achieve a balanced etching rate. This composition range ensures that the oxide layer etches slowly enough to maintain high selectivity (ratio > 30:1) but not so slowly that the overall process time becomes excessive. The nitride layer composition (90-99 at% nitrogen) is simultaneously optimized to etch at an appropriate rate for efficient removal.
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 simplifies the etching process by eliminating the need for dummy spacers, reduces substrate damage, and improves the overall quality of the semiconductor structure.
Implementation Method 1
the etching selectivity ratio of etching a nitride material to etching an oxide material is greater than 300
Data Source
AI summary
The invention provides an etching method of a semiconductor structure, which comprises providing a substrate with a gate structure, an oxide layer and a first nitride layer beside the gate structure, and performing an etching step to remove the first nitride layer and keep the oxide layer, wherein in the etching step, the etching selectivity ratio of the etched nitride material to the etched oxide material is greater than 300.