Semiconductor Device Field Plate Effect Electric Field Concentration
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Solution Overview
Problem
Bipolar complementary metal oxide semiconductor (BiC-DMOS) transistors, specifically laterally diffused metal oxide semiconductor (LDMOS) transistors, experience erroneous operation due to electric field concentration at the substrate surface, leading to low withstand voltage, as the gate, source, and body are short-circuited, causing current flow in reverse direction at low voltage regions.
Innovation Solution
A semiconductor device with a semiconductor substrate, a first-conductivity-type body region, a second-conductivity-type drain region, a second-conductivity-type source region, and a gate electrode, where the gate, source, and body regions are electrically coupled, and a first impurity region with higher conductivity-type impurity concentration is disposed between the body and source regions, providing a field plate effect to relieve electric field concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the gate, source, and body are short-circuited to configure an anode isolated diode, then the diode structure is simplified and operation voltage range is widened, but electric field concentration at the substrate surface occurs leading to low withstand voltage
Solution Approach 1:
A first impurity region with higher concentration of first-conductivity-type impurity than the body region is introduced as an intermediary structure between the body region and source region. This impurity region acts as a mediator that modifies the electric field distribution, preventing direct concentration at the substrate surface while maintaining the short-circuited gate-source-body configuration for diode operation.
Solution Approach 2:
The impurity concentration is made non-uniform by creating a first impurity region with higher impurity concentration than the body region. This local variation in electrical properties (conductivity) allows the structure to maintain diode functionality in some regions while providing enhanced withstand voltage capability in other regions through the modified electric field distribution.
2Ease of operation
If the gate, source, and body are short-circuited, then the AID structure is formed, but a channel is formed when negative voltage is applied to the gate causing current flow and erroneous operation
Solution Approach 1:
The first impurity region serves as an intermediary that prevents channel formation between the body and source regions. By introducing this region with higher impurity concentration, the electrical characteristics are modified to block unwanted current flow paths that would otherwise form when negative voltage is applied to the gate, thereby preventing erroneous operation.
3Device complexity
If no gate is present as in bipolar transistor, then the structure is simpler, but field plate effect is not provided allowing electric field concentration leading to low withstand voltage
Solution Approach 1:
The first impurity region acts as a substitute intermediary structure that performs the field plate effect function normally provided by a gate. By creating this impurity region with higher concentration, the patent achieves electric field distribution control and withstand voltage enhancement without requiring a physical gate structure, thus maintaining simplicity while improving performance.
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 prevents erroneous operation and enhances the withstand voltage by reducing electric field concentration at the substrate surface, ensuring reliable operation even at low voltage regions.
Implementation Method 1
The gate electrode, the source region, and the body region are electrically coupled to one another... providing a field plate effect to relieve electric field concentration
Implementation Method 2
The first impurity region has a higher concentration of a first-conductivity-type impurity than the body region
Data Source
AI summary
Provided are a semiconductor device capable of preventing erroneous operation and providing a field plate effect, and a method of manufacturing the semiconductor device. In a diode, a gate electrode, a p+ source region, and an n-type body region are electrically coupled to one another. A contact region is disposed between the n-type body region and the p+ source region in a first surface of a semiconductor substrate.