Semiconductor Gate Structure Width and Profile Optimization
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Solution Overview
Problem
Polysilicon gate electrodes in semiconductor devices have high resistance, leading to lower operating speeds compared to metal gate electrodes, and existing replacement methods like the replacement metal gate (RMG) process are inefficient in addressing this issue.
Innovation Solution
The semiconductor device features a combination of first and second gate structures with distinct widths and surface profiles on a semiconductor substrate, where the first gate structure has a flat upper surface and a narrower width, and the second gate structure has a convex upper surface and a wider width, fabricated using a method involving dummy gate structures, spacers, interlayer insulating films, and planarization processes to improve performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If polysilicon gate electrode is used, then high temperature durability is improved, but resistance increases leading to lower operating speed
Solution Approach 1:
The gate electrode is segmented into two parts: a polysilicon portion for high-temperature durability and a metal portion for low resistance. This segmentation allows each material to perform its optimal function - polysilicon in regions requiring thermal stability and metal in regions requiring electrical conductivity, thereby resolving the contradiction between temperature durability and operating speed.
Solution Approach 2:
The gate electrode uses a composite structure combining polysilicon and metal materials. This composite approach leverages the high-temperature stability of polysilicon and the low resistance of metal, achieving both high temperature durability and high operating speed that neither material could provide alone.
2Reliability
If replacement metal gate process is used, then resistance is reduced, but manufacturing complexity increases
Solution Approach 1:
Dummy gate structures are formed in advance during the manufacturing process, which serve as placeholders that guide subsequent spacer formation and metal gate deposition. This preliminary action simplifies the overall RMG process by providing a structured framework that reduces manufacturing complexity while achieving the desired resistance reduction.
Solution Approach 2:
Dummy gate structures act as intermediaries during the manufacturing process, facilitating the transition from initial substrate preparation to final metal gate formation. These temporary structures enable precise positioning and formation of spacers and metal gates, reducing process complexity by providing a mediating framework.
3Speed
If gate structure width is increased, then operating performance is improved, but area occupied increases
Solution Approach 1:
The gate structure implements local quality by having different widths in different regions - a first width in the first region and a second (larger) width in the second region. This allows the gate to have increased width for improved performance where needed, while maintaining compact dimensions in other areas, thereby optimizing the balance between operating performance and area occupation.
Data Source
AI summary
A semiconductor device includes at least one first gate structure and at least one second gate structure on a semiconductor substrate. The at least one first gate structure has a flat upper surface extending in a first direction and a first width in a second direction perpendicular to the first direction. The at least one second gate structure has a convex upper surface extending in the first direction and a second width in the second direction, the second width being greater than the first width.