Selective Silicon Nitride Retention for Stable Gate Silicidation
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Solution Overview
Problem
The emission of nitrogen gas from silicon nitride during plasma cleaning in semiconductor device fabrication disrupts the plasma environment, destabilizing the reaction and affecting the quality and yield of siliciding processes.
Innovation Solution
A process involving the formation of a protective layer with a silicon oxide and silicon nitride stack, followed by selective etching to remove a portion of the silicon nitride layer, ensuring that only a minimal amount of silicon nitride remains, primarily on the border between silicided and non-silicided areas, thereby stabilizing the plasma environment during ion sputtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion sputtering in plasma environment is used for cleaning silicon surfaces, then cleaning effectiveness is improved, but plasma stability deteriorates due to nitrogen gas emission from silicon nitride
Solution Approach 1:
The patent removes the silicon nitride layer completely from areas where plasma cleaning will be performed, extracting the source of nitrogen gas emission before the plasma process. This prevents nitrogen from disrupting plasma equilibrium while maintaining the protective layer's function of preventing unwanted silicidation in non-target areas.
Solution Approach 2:
The patent applies different layer configurations to different regions of the semiconductor device. The silicon nitride protective layer is selectively removed from certain areas while maintained in others, creating local variations in material composition that optimize both cleaning effectiveness and plasma stability in different regions.
2Stability of the object's composition
If complete removal of silicon nitride layer is performed, then plasma stability is improved, but protective layer functionality deteriorates
Solution Approach 1:
The patent creates spatially varying protective layer structures where silicon nitride is completely removed in plasma cleaning zones but retained in areas requiring protection during silicidation. This local differentiation maintains plasma stability where needed while preserving protective functionality where required.
Solution Approach 2:
The protective layer is segmented into different regions with different compositions: areas with complete silicon nitride removal for plasma stability and areas with retained silicon nitride for protection. This segmentation allows simultaneous optimization of plasma process stability and protective layer functionality across different device regions.
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 approach optimizes the ion sputtering process, improving the quality and yield of semiconductor device production by preventing plasma destabilization and enhancing metal-silicon contacts, resulting in better device performance.
Implementation Method 1
siliciding the part to be silicided by an ion sputtering in a plasma environment
Implementation Method 2
ion sputtering in a plasma environment
Data Source
AI summary
A exemplary semiconductor device includes a first gate structure overlying a surface of the semiconductor body, the first gate structure being silicided. A second gate structure overlies the surface of the semiconductor body and not being silicided. An oxide layer overlies the second gate structure and extends toward the first gate structure. A silicon nitride region is laterally spaced from the second gate structure and overlies a portion of the oxide layer between the first gate structure and the second gate structure.