Power Semiconductor Device With Impurity Doping Profile
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Solution Overview
Problem
Existing power semiconductor devices, such as IGBTs, face challenges in maximizing conductivity modulation and reducing conduction loss due to the movement of hole carriers, which affects their performance in high voltage and high current applications.
Innovation Solution
A method of manufacturing power semiconductor devices involves forming a base substrate with a first conductive type drift layer, creating primary and secondary trenches, and forming a first conductive type diffusion layer with a higher concentration than the drift layer, where the peak impurity doping profile is positioned between the second conductive type well layer and the lower surface of the secondary trench, allowing for enhanced hole carrier accumulation and reduced conduction loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a wide trench-to-trench region is used to allow hole carrier movement for conductivity modulation, then conduction loss is reduced, but threshold voltage variation increases and device stability deteriorates
Solution Approach 1:
The patent applies local quality by creating different impurity concentration zones within the drift layer. A first conductive type diffusion layer with higher impurity concentration is formed in specific regions (at least at the surface) compared to the base drift layer. This local variation in impurity concentration allows hole carrier accumulation and conductivity modulation in targeted areas while maintaining overall device stability and reducing threshold voltage variation.
Solution Approach 2:
The patent changes the impurity concentration parameter by forming a diffusion layer with higher impurity concentration than the base drift layer. The impurity concentration in the diffusion layer is specifically controlled to be higher, which enables conductivity modulation through hole carrier accumulation while maintaining device reliability. The peak impurity concentration is positioned at or near the surface to optimize the conductivity modulation effect.
2Loss of energy
If ion injection and thermal diffusion are used to form high concentration diffusion layers, then conductivity modulation is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by forming the first conductive type diffusion layer through ion injection and thermal diffusion before subsequent processing steps. The etching resist is formed with a specific pattern that defines where the diffusion layer will be created, and the ion injection is performed through this resist pattern. This preliminary formation of the diffusion layer with controlled impurity concentration enables subsequent trench formation and device assembly without requiring additional complex processing steps.
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 decreases conduction loss and variation in threshold voltage, increasing switching speed and improving overall device operation by limiting hole carrier movement and optimizing impurity doping profiles.
Implementation Method 1
performing ion injection and thermal diffusion on the primary trench to form a first conductive type diffusion layer having a concentration higher than that of the first conductive type drift layer
Implementation Method 2
performing ion injection and thermal diffusion on the primary trench to form a first conductive type diffusion layer
Implementation Method 3
this bipolar operation generates conductivity modulation phenomenon to reduce series resistance depending on a raw material of a wafer at the time of a turn-on operation of the IGBT device
Implementation Method 4
The hole carriers are generated by holes injected from a P-collector layer
Data Source
AI summary
Disclosed herein is a power semiconductor device including: a base substrate having one surface and the other surface and formed of a first conductive type drift layer; a first conductive type diffusion layer formed on one surface of the base substrate and having a concentration higher than that of the first conductive type drift layer; and a trench formed so as to penetrate through the second conductive type well layer and the first conductive type diffusion layer from one surface of the base substrate including the second conductive type well layer in a thickness direction.