DMOS Transistor Dopant Profile for Parasitic Suppression
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Solution Overview
Problem
There is a need to enhance the breakdown resistance and reliability of semiconductor devices, particularly in Metal Oxide Semiconductor (MOS) transistors, to improve the Safe Operating Area (SOA) and resistance to Electrical Static Destruction (ESD) by suppressing the operation of parasitic npn bipolar transistors.
Innovation Solution
The semiconductor device design includes a first well region of a first conductive type and a second well region of a second conductive type, with a higher dopant concentration in specific regions to redirect electric field concentration away from the channel region, thereby reducing impact ion generation and increasing the resistance to ESD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a channel region is formed by a double diffusion process in a DMOS transistor, then the breakdown resistance is improved, but the parasitic npn bipolar transistor operation is not sufficiently suppressed
Solution Approach 1:
The patent introduces an intermediate region with a specific dopant concentration profile between the source and drain regions. This region has a dopant concentration that is lower than both the source/drain regions and higher than the drift region, creating a localized electrical field distribution that suppresses parasitic transistor operation while preserving breakdown resistance in other regions.
Solution Approach 2:
The patent modifies the dopant concentration parameter in the intermediate region to achieve the desired effect. By setting the dopant concentration in the intermediate region to be lower than in the source/drain regions but higher than in the drift region, the electrical field distribution is altered to suppress impact ionization and parasitic transistor operation without compromising the overall breakdown resistance.
2Reliability
If the dopant concentration is increased in the drift region to improve breakdown resistance, then the SOA is improved, but the impact ion generation increases
Solution Approach 1:
The patent creates a specific dopant concentration profile in the intermediate region that differs from both the drift region and source/drain regions. This localized modification allows the drift region to maintain high dopant concentration for breakdown resistance while the intermediate region provides a transition zone that reduces impact ion generation through optimized field distribution.
Solution Approach 2:
The patent divides the region between source and drain into multiple zones with different dopant concentrations: the drift region, the intermediate region, and the source/drain regions. This segmentation allows each zone to be optimized for its specific function - the drift region for breakdown resistance and the intermediate region for suppressing impact ionization.
3Productivity
If the channel region dimensions are reduced to improve device integration, then the device density is improved, but the ESD resistance is reduced
Solution Approach 1:
The patent addresses the ESD resistance issue by introducing a vertical dimension to the dopant concentration profile through the intermediate region. Instead of merely scaling horizontal dimensions, the invention creates a three-dimensional dopant distribution with the intermediate region extending vertically between the source/drain regions, providing ESD protection without compromising planar integration.
Solution Approach 2:
The patent modifies the dopant concentration parameter in the intermediate region to provide ESD resistance. By maintaining a specific dopant concentration range in the intermediate region (lower than source/drain but higher than drift), the device achieves improved ESD resistance even with reduced channel dimensions, as the intermediate region provides an additional protection mechanism independent of channel size.
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 design effectively suppresses the operation of parasitic transistors, enhancing the SOA and ESD resistance by minimizing impact ionization and electric current flow through the channel region, thereby improving the reliability and performance of the semiconductor device.
Implementation Method 1
redirect electric field concentration away from the channel region
Implementation Method 2
reducing impact ion generation
Data Source
AI summary
A semiconductor device includes a semiconductor region, a first well region which has a first conductive type, a second well region which has a second conductive type, a source region, a drain region, a channel region, and a gate insulation film. The first well region and the second well region are formed in the semiconductor region adjacent to each other. The source region is on the first well region; the drain region is on the second well region. The semiconductor region has a first region, a second region, and a third region. A dopant concentration of the second conductive type in the third region is higher than a dopant concentration of the second conductive type in the first region.