Semiconductor Device Buried and Recess Gate Structures
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Solution Overview
Problem
As semiconductor devices evolve with smaller transistor channel lengths, the standard deviation of threshold voltages increases, necessitating a solution to reduce this variability while maintaining manufacturing ease.
Innovation Solution
The semiconductor device incorporates a recess channel transistor design with buried and recess gate structures, utilizing metal gates to prevent polysilicon depletion and reduce threshold voltage standard deviation, where the work function adjustment layers in both structures are made of the same material to enhance manufacturing simplicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the channel length of a transistor is decreased to reduce the area occupied by each transistor, then the area efficiency is improved, but the standard deviation of threshold voltages increases
Solution Approach 1:
The gate structure is segmented into two distinct types: buried gate structures for first transistors and recess gate structures for second transistors. This segmentation allows each transistor type to have optimized channel length control mechanisms, thereby reducing threshold voltage standard deviation while maintaining small area occupancy.
Solution Approach 2:
Different gate structures are applied to different regions of the substrate. The buried gate structure is used in the first region while the recess gate structure is used in the second region. This local differentiation enables tailored threshold voltage control for each region, reducing overall standard deviation while maintaining area efficiency.
2Manufacturing precision
If different work function adjustment layer materials are used for buried gate and recess gate structures to optimize performance, then the threshold voltage control is improved, but the manufacturing complexity increases
Solution Approach 1:
The same work function adjustment layer material is used for both buried gate structures and recess gate structures. This universal material selection simplifies the manufacturing process by reducing the number of material types that need to be handled, deposited, and processed, while still achieving effective threshold voltage control for both transistor types.
Solution Approach 2:
The work function adjustment layer is made homogeneous in material composition across different gate structures. This homogeneity simplifies the deposition process and material management, reducing manufacturing complexity while maintaining the ability to control threshold voltages for both buried and recess gate transistors.
Data Source
AI summary
A semiconductor device includes a substrate including a first region and a second region, a buried gate structure located on a first recess in the first region of the substrate, and a recess gate structure located on a second recess in the second region of the substrate, wherein the buried gate structure is buried in the substrate, an upper portion of the recess gate structure is not buried in the substrate, and a first work function adjustment layer in the buried gate structure may include a material identical to a material included in a second work function layer of the recess gate structure.