Polysilicon Protective Layer for OTP Leakage and Silicide Yield
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Solution Overview
Problem
The thickness of the protective layer in the one-time-programmable (OTP) part of an integrated circuit affects the performance of logic circuits and static random access memory (SRAM), and residue materials from the protective layer formation can hinder subsequent silicidation processes.
Innovation Solution
A conformal protective layer is formed over the polysilicon structures and spacers in the logic and SRAM parts, ensuring a sufficient thickness for protection and a narrow thickness difference for easy removal, enhancing the silicide formation and preventing leakage in the OTP part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the protective layer thickness is increased to prevent leakage in the OTP part, then the protection performance is improved, but the residue materials from the protective layer formation hinder subsequent silicidation processes in the logic and SRAM parts
Solution Approach 1:
The patent applies different thicknesses of the protective layer to different regions: a first thickness in the OTP part for leakage prevention, and a second (thinner) thickness in the logic and SRAM parts to avoid residue issues. This local differentiation resolves the contradiction by tailoring the protective layer properties to specific functional requirements of each circuit block.
2Reliability
If the protective layer thickness is varied across different parts of the integrated circuit, then the performance of each part is optimized, but the manufacturing complexity increases
Solution Approach 1:
The patent forms a conformal protective layer that uniformly covers the entire surface before any selective removal. This preliminary conformal deposition simplifies the manufacturing process, and subsequent selective removal in specific areas (logic and SRAM parts) creates the desired thickness variation without requiring complex multi-step deposition processes.
Data Source
AI summary
A method of making a semiconductor device includes forming a first polysilicon structure over a first portion of a substrate. The method further includes forming a first spacer on a sidewall of the first polysilicon structure, wherein the first spacer has a concave corner region between an upper portion and a lower portion. The method further includes forming a protective layer covering an entirety of the first spacer and the first polysilicon structure, wherein the protective layer has a first thickness over the concave corner region and a second thickness over the first polysilicon structure, and a difference between the first thickness and the second thickness is at most 10% of the second thickness.