Semiconductor Stress Layer Removal via Segmented Etching
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Solution Overview
Problem
The miniaturization of semiconductor devices leads to reduced carrier mobility in transistors, and existing stress memorization techniques damage spacers during stress layer removal, causing circuit leakages.
Innovation Solution
A semiconductor process that performs a dry etching process to remove parts of a stress layer and then a wet etching process to entirely remove the stress layer, ensuring the spacer is not damaged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a wet etching process is used to remove the stress layer, then the stress layer can be entirely removed, but the spacer will be damaged causing circuit leakages
Solution Approach 1:
The patent segments the stress layer removal process into two distinct stages: first a dry etching process that removes portions of the stress layer, then a wet etching process that removes the remaining stress layer. This segmentation allows each process to be optimized independently - the dry etching provides controlled removal while the wet etching completes the removal without damaging the spacer
Solution Approach 2:
The patent introduces an intermediary approach by using the dry etching process as a preliminary step before the wet etching. The dry etching acts as a mediator that prepares the stress layer for complete removal by the wet etching, enabling the wet etching to complete the removal without directly attacking the spacer with aggressive chemicals
2Reliability
If the stress layer is completely removed to enhance carrier mobility, then transistor performance improves, but the spacer material is similar to stress layer causing damage during removal
Solution Approach 1:
The removal process is divided into two segments: dry etching that selectively removes portions of the stress layer while being gentler on the spacer, followed by wet etching that completes the removal. This segmentation enables complete stress layer removal for enhanced carrier mobility while protecting the spacer from damage
Solution Approach 2:
The patent changes the etching parameters by switching from a single wet etching process to a combination of dry and wet etching processes. The dry etching uses different chemical and physical parameters compared to wet etching, allowing selective removal of the stress layer while preserving the spacer material
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 allows for the complete removal of the stress layer without damaging the spacer, enhancing transistor performance by maintaining carrier mobility and preventing circuit leakages.
Implementation Method 1
A dry etching process is performed to remove parts of the nitride layer on the first structure
Implementation Method 2
A wet etching process is performed to entirely remove the nitride layer and the oxide layer on the first structure and the second structure
Data Source
AI summary
A semiconductor process includes the following steps. A first structure and a second structure are formed on a substrate. An oxide layer is entirely formed to cover the first structure and the second structure. A nitride layer is formed to entirely cover the oxide layer. A dry etching process is performed to remove a part of the nitride layer on the first structure. A wet etching process is performed to entirely remove the nitride layer and the oxide layer on the first structure and the second structure.