DMOS Doped Ring Implantation for Breakdown Voltage and On-Resistance
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Solution Overview
Problem
Double-diffused metal oxide semiconductor (DMOS) transistors face challenges in optimizing breakdown voltage and on-state resistance, particularly in high voltage applications, where existing body contact structures do not adequately manage electric fields and resistance.
Innovation Solution
The formation of doped rings in a semiconductor device, implanted through a trench in an epitaxial layer, with a dielectric material filling the trench, allows for adjustable breakdown voltage and on-state resistance by optimizing the placement and depth of p-type and n-type doped rings, and the inclusion of a twelve-sided body tie structure for improved contact efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing body contact structures are used in DMOS transistors, then the device can be manufactured with standard structures, but the breakdown voltage and on-state resistance cannot be optimized for high voltage applications
Solution Approach 1:
The body contact structure is segmented into multiple doped rings (first doped ring, second doped ring, third doped ring) with different doping types and concentrations arranged in sequence. This segmentation allows each ring to perform specific functions in managing electric fields, thereby optimizing breakdown voltage without requiring complete structural redesign
Solution Approach 2:
Different regions of the body contact structure are assigned different doping types (p-type and n-type) and doping concentrations to create localized electrical properties. The first doped ring has different characteristics than the second and third rings, allowing optimization of electric field distribution at specific locations to enhance breakdown voltage
2Reliability
If existing body contact structures are used in DMOS transistors, then the manufacturing process remains simple, but the on-state resistance cannot be reduced for high voltage applications
Solution Approach 1:
The body contact is divided into multiple doped rings with progressively varying doping characteristics. This segmentation creates a gradient structure that facilitates carrier transport while managing electric fields, thereby reducing on-state resistance through optimized charge distribution across the drift region
Solution Approach 2:
The doping type and concentration parameters are changed across different rings (first, second, and third doped rings) to optimize electrical properties. By adjusting these parameters in a controlled manner, the structure achieves lower on-state resistance while maintaining manageable complexity
3Reliability
If doped rings are implanted through a trench with dielectric material, then breakdown voltage and on-state resistance can be optimized, but the manufacturing process becomes more complex
Solution Approach 1:
The trench is formed and filled with dielectric material before the doped rings are implanted. This preliminary action creates a structured template that guides the implantation process, allowing precise placement of doped rings at specific depths and positions to optimize electric field management
Solution Approach 2:
The dielectric material filling the trench serves as an intermediary that isolates and positions the doped rings during implantation. This intermediary structure enables controlled doping at specific locations while protecting surrounding regions, thereby managing manufacturing complexity
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 approach enhances the breakdown voltage and reduces on-state resistance by managing electric fields and increasing free carrier density, thereby improving the performance of DMOS transistors in high voltage applications.
Implementation Method 1
implanting at least one doped ring through the trench and into the epitaxial layer
Implementation Method 2
a dielectric material filling within the trench
Data Source
AI summary
According to one aspect of the present disclosure, a semiconductor device includes a substrate having a first type dopant. In some embodiments, the semiconductor device also includes an epitaxial layer above the substrate, having a second type dopant and a top region. In some embodiments, the semiconductor device also includes a trench in the top region of the epitaxial layer; at least one doped ring implanted in the epitaxial layer below the trench; and a dielectric material filling within the trench. In some embodiments, there is a twelve-sided body tie in the epitaxial layer, wherein the sides of the twelve-sided body tie are not all equal to each other.