IGBT Built-in Diode Terminal Protection Area Segmentation
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Solution Overview
Problem
Conventional IGBTs with built-in diodes have poor recovery characteristics due to the distribution of N+ and P+ regions across the entire backside region, including the active and terminal protection areas, which affects their performance under inductive loads.
Innovation Solution
The IGBT design includes a semiconductor substrate with a built-in diode where the first and second semiconductor layers are spaced apart on the active region, and only the second semiconductor layer is formed on the terminal protection area, optimizing the reverse recovery characteristics without compromising the IGBT's properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If N+ and P+ regions are distributed across the whole backside region including terminal protection area, then the built-in diode can be formed, but the recovery characteristic becomes poor
Solution Approach 1:
The backside region is segmented into active region and terminal protection area, with different semiconductor layer configurations in each zone. The N+ and P+ regions are only formed in the active region, while the terminal protection area has a simplified structure without these doped regions, thereby improving recovery characteristics while maintaining manufacturability
Solution Approach 2:
Different structural qualities are applied to different spatial zones: the active region contains the complete N+ and P+ doped regions for diode functionality, while the terminal protection area uses a simplified structure without these regions. This local differentiation optimizes recovery characteristics in the protection area while maintaining diode operation in the active region
2Manufacturing precision
If N+ and P+ regions are formed by two backside photolithography techniques, then spaced regions can be created, but the recovery characteristic deteriorates
Solution Approach 1:
The N+ and P+ region formation process is extracted from the terminal protection area and confined only to the active region. This removes the harmful effect of doped regions in the protection area while preserving the necessary spaced region structure in the active region for proper diode operation
Solution Approach 2:
The photolithography process is segmented to apply different patterns to different regions: the active region receives the full pattern with spaced N+ and P+ regions, while the terminal protection area receives a simplified pattern without these doped regions, thereby achieving both manufacturing precision and improved recovery characteristics
Data Source
AI summary
An insulated gate bipolar translator (IGBT) with a built-in diode and a manufacturing method thereof are provided. The IGBT comprises: a semiconductor substrate (1) of the first conduction type which has a first major surface (1S1) and a second major surface (1S2), wherein the semiconductor substrate (1) comprises an active region (100) and a terminal protection area (200) which is located at the outer side of the active region; an insulated gate transistor unit which is formed at the side of the first major surface (1S1) of the active region (100), wherein a channel of the first conduction type is formed thereon during the conduction thereof; and first semiconductor layers (10) of the first conduction type and second semiconductor layers (11) of the second conduction type of the active region, which are formed at the side of the second major surface (1S2) of the semiconductor substrate (1) alternately, wherein the IGBT only comprises the second semiconductor layers (11) in the terminal protection area (200) which is located at the side of the second major surface (1S2) of the semiconductor substrate (1).