Asymmetric Double Diffused Drain Structure for Medium Voltage Devices
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Solution Overview
Problem
Existing semiconductor structures with double diffused drains (DDD) face challenges in maintaining desired electrical performance and reducing device size, as the design rule of the diffusion region under the channel region is critical for voltage stability and on-resistance, but current designs occupy a large area.
Innovation Solution
A semiconductor structure with a first diffusion region having a larger first portion under the gate and a smaller second portion protruded laterally, allowing for reduced total area while maintaining desired electrical performance, achieved by optimizing the lengths of these portions and using a manufacturing method that forms these regions with specific dimensions and dopant concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the diffusion region is extended laterally to reduce device size, then the device area is reduced, but the electrical performance (threshold voltage stability and on-resistance) deteriorates
Solution Approach 1:
The diffusion region is segmented into two distinct portions: a first portion extending under the gate with sufficient length to maintain electrical performance, and a second portion extending laterally to reduce device area. This segmentation allows each portion to fulfill different functional requirements independently.
Solution Approach 2:
Different portions of the diffusion region are given different lengths and configurations tailored to their specific functions. The first portion under the gate is designed with sufficient length for electrical stability, while the second lateral portion is optimized for area reduction, creating local quality variations that resolve the contradiction.
2Area of moving object
If the first diffusion region is made compact to reduce device size, then the device area is reduced, but the threshold voltage stability and on-resistance performance deteriorate
Solution Approach 1:
The diffusion region is divided into functional segments where the first portion under the gate maintains sufficient length for stable threshold voltage and on-resistance, while the overall structure remains compact due to the optimized configuration of both portions.
Solution Approach 2:
The diffusion region exhibits asymmetric configuration with the first portion under the gate having a different length characteristic than the second lateral portion, allowing optimal electrical performance in the critical gate region while achieving compact overall dimensions through the shorter lateral extension.
Data Source
AI summary
A semiconductor structure and a manufacturing method of a semiconductor structure are provided. The semiconductor structure includes a semiconductor substrate, a gate, a first diffusion region and a second diffusion region. The gate is disposed on the semiconductor substrate and extends along a first direction. The first diffusion region is formed in the semiconductor substrate, and the second diffusion region is formed in the first diffusion region. The first diffusion region has a first portion located underneath the gate and a second portion protruded from a lateral side of the gate, the first portion has a first length parallel to the first direction, the second portion has a second length parallel to the first direction, and the first length is larger than the second length.