IGBT Diode Integration Segmentation Optimization
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Solution Overview
Problem
The integration of a diode within an insulated gate bipolar transistor (IGBT) leads to deteriorated ON characteristics and elevated forward voltage, as well as increased recovery current, due to reduced conducting regions and higher carrier density near the surface, which complicates the operation of both the IGBT and the diode.
Innovation Solution
The design incorporates a semiconductor device with distinct regions for IGBT and diode operation, where the IGBT region has emitter layers between trenches and the diode region does not, allowing for separate optimization of trench intervals and impurity concentrations to enhance ON characteristics and reduce forward voltage and recovery current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a diode is integrated within an IGBT structure, then the device complexity is reduced and space is saved, but the ON characteristics deteriorate and forward voltage increases
Solution Approach 1:
The semiconductor device is divided into distinct first and second regions with different structures. The first region contains emitter layers and is optimized for IGBT operation, while the second region lacks emitter layers and is optimized for diode operation. This segmentation allows each region to be independently optimized, resolving the contradiction between integration and performance.
Solution Approach 2:
Different regions of the semiconductor device are given different local structures and properties. The first region has emitter layers with specific impurity concentrations optimized for transistor action, while the second region has different impurity concentrations optimized for diode action. This local differentiation enables both IGBT and diode functions to operate with optimal characteristics simultaneously.
2Area of stationary object
If a diode is integrated within an IGBT structure, then space is saved, but recovery current increases
Solution Approach 1:
The device is segmented into separate first and second regions, allowing the diode region (second region) to be optimized independently for low recovery current characteristics through controlled impurity concentrations, while maintaining compact integration with the IGBT region.
Solution Approach 2:
The second region is given specific local quality characteristics with impurity concentrations optimized for diode operation, including controlled doping levels that minimize recovery current. This local optimization reduces harmful recovery current effects while maintaining space-efficient integration.
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 improves the ON characteristics of the IGBT and diode by maintaining low forward voltage and recovery current, while allowing for independent control of IGBT and diode performance, thereby addressing the issues of elevated forward voltage and increased recovery current.
Implementation Method 1
an insulating film coating the inner surfaces of the trenches
Implementation Method 2
a conductive film buried in the trenches through the insulating film
Implementation Method 3
an emitter layer 3 wherein an n-type impurity of a high concentration is selectively diffused
Implementation Method 4
electrons are injected into the N− layer 1 from the emitter electrode 11
Implementation Method 5
the channel region is reversed to the n-type, and a channel is formed
Implementation Method 6
a P base layer 2 wherein a p-type impurity is diffused is selectively formed
Data Source
AI summary
There is provided a structure wherein an emitter layer 3 is provided in the region A on the first major surface side of a semiconductor substrate 1, and emitter layer 3 is not provided in the region b. There is provided a structure wherein a collector P layer 5 is provided in the region A on the second major surface side of a semiconductor substrate 1, and a cathode N layer 4 is provided in the region B. Specifically, there is provided a structure wherein IGBTs are composed in the region A, and diodes are composed in the region B. By the above-described structure, ON characteristics when the gate is turned on can be improved while suppressing the elevation of the forward voltage Vf and the recovery current of the diodes.