MOSFET Gate Structure With Split Doping for Breakdown and On-Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor devices, such as MOSFETs, face challenges in suppressing breakdown and reducing resistance during ON operation due to non-uniform polysilicon grain sizes and inadequate insulating film thickness, leading to potential short circuits and reduced breakdown tolerance.
Innovation Solution
The semiconductor device incorporates a conductive portion with a high impurity concentration and a second conductive portion with a lower impurity concentration, where the second conductive portion is oxidized to form a uniform insulating layer, reducing grain size variations and maintaining breakdown voltage while minimizing connection resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single conductive portion with high impurity concentration is used, then connection resistance is reduced, but insulating film thickness becomes non-uniform and breakdown tolerance decreases
Solution Approach 1:
The conductive portion is divided into two segments: a first conductive portion with high impurity concentration for low connection resistance, and a second conductive portion with lower impurity concentration that forms a uniform insulating film. This segmentation allows each part to fulfill its specific function without compromising the other, resolving the contradiction between connection resistance and insulating film uniformity
Solution Approach 2:
Different regions of the conductive portion are assigned different impurity concentrations based on their functional requirements. The first conductive portion (near the source/drain) has high impurity concentration for electrical connection, while the second conductive portion (near the gate) has lower impurity concentration for forming a uniform insulating film, achieving local optimization of properties
2Reliability
If polysilicon grain size is not controlled, then manufacturing is simpler, but insulating film thickness varies and breakdown occurs
Solution Approach 1:
The impurity concentration parameter is changed in the second conductive portion to achieve uniform polysilicon grain size. By controlling the impurity concentration to be lower in the second conductive portion, the polysilicon grains grow uniformly, which in turn ensures uniform insulating film thickness and prevents breakdown, achieving reliable operation through parameter optimization
3Reliability
If insulating film thickness is increased to prevent breakdown, then breakdown tolerance improves, but on-resistance increases
Solution Approach 1:
The insulating film thickness is optimized locally by controlling the impurity concentration in different conductive portions. The second conductive portion has lower impurity concentration that promotes uniform grain growth and forms an insulating film of appropriate thickness for breakdown prevention, while the first conductive portion maintains high impurity concentration for low on-resistance, achieving both reliability and low resistance through localized property control
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 configuration enhances the breakdown tolerance of the insulating film, suppresses breakdown during operation, and reduces on-resistance by promoting depletion layer formation, thereby improving the reliability and efficiency of the semiconductor device.
Implementation Method 1
the second conductive portion is oxidized to form a uniform insulating layer
Implementation Method 2
reduces on-resistance by promoting depletion layer formation
Data Source
AI summary
A semiconductor device of embodiments includes a first electrode, a second electrode, a first semiconductor region, a second semiconductor region, a third semiconductor region, a conductive portion, a first insulating portion, a gate electrode, a second insulating portion, and a third insulating portion. The first to third semiconductor regions are provided between the first electrode and the second electrode. The conductive portion includes a first conductive portion and a second conductive portion on the second electrode side and having a lower impurity concentration than the first conductive portion. The first insulating portion is provided between the first conductive portion and the first semiconductor region. The gate electrode is provided between the second semiconductor region and the second conductive portion. The second insulating portion is provided between the second conductive portion and the gate electrode. The third insulating portion is provided between the second semiconductor region and the gate electrode.