Semiconductor Crystal Defect Depth Control for Reverse Recovery
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Solution Overview
Problem
Existing vertical semiconductor devices face challenges in controlling carrier lifetime while maintaining breakdown voltage, as irradiating accelerated ions over the entire rear surface can lower breakdown voltage and affect reverse recovery time.
Innovation Solution
A semiconductor device with selectively designated active and inactive regions, where a crystal defect region is formed at different depths in each region to control carrier lifetime and prevent breakdown voltage reduction, using charged particles like protons or helium ions, and a method involving level differences and precise positioning to form these regions without shielding, enhancing precision and productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If accelerated ions are irradiated over the entire rear surface to control carrier lifetime, then reverse recovery time is reduced, but breakdown voltage is lowered
Solution Approach 1:
The semiconductor device is divided into active regions and inactive regions. Crystal defect regions are selectively formed only in the active regions through targeted ion irradiation, while inactive regions remain free of such defects. This segmentation allows carrier lifetime control in active regions without compromising breakdown voltage in inactive regions.
Solution Approach 2:
Different regions of the semiconductor device are given different properties: active regions contain crystal defect regions that reduce carrier lifetime and reverse recovery time, while inactive regions maintain high breakdown voltage by excluding crystal defects. This local differentiation resolves the contradiction between speed and voltage handling capability.
2Reliability
If crystal defect regions are formed to control carrier lifetime, then reverse recovery characteristics improve, but breakdown voltage may be reduced
Solution Approach 1:
The device structure is segmented into active and inactive regions with different functional requirements. Crystal defect regions are formed exclusively in active regions where reverse recovery characteristics are critical, while inactive regions maintain their original crystal structure to preserve breakdown voltage.
Solution Approach 2:
Crystal defect regions are locally introduced only where needed for reverse recovery control. The inactive regions maintain high-quality crystal structure optimized for voltage blocking, while active regions have modified crystal structure optimized for fast switching.
3Productivity
If ion irradiation is applied to the entire rear surface, then carrier lifetime is controlled uniformly, but breakdown voltage and manufacturing precision are affected
Solution Approach 1:
The irradiation process is segmented to target only active regions. By defining active regions through masks or alignment markers before ion irradiation, the process achieves both high productivity through selective treatment and high precision by avoiding inactive regions that require high breakdown voltage.
Solution Approach 2:
Active regions are pre-defined and marked before ion irradiation. This preliminary action enables precise targeting of ion beams to active regions only, ensuring that carrier lifetime control is applied exactly where needed without affecting breakdown voltage in inactive regions.
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 allows for precise control of carrier lifetime and maintains breakdown voltage by strategically placing crystal defect regions, reducing reverse recovery time in the active region while minimizing impact on breakdown voltage in the inactive region, thus improving semiconductor device performance.
Implementation Method 1
accelerated ions such as proton, helium or the like are irradiated initially to a rear surface of a silicon substrate
Implementation Method 2
a crystal defect region is formed in both of the active region and the inactive region
Data Source
AI summary
A semiconductor device includes: an n type semiconductor layer including an active region and an inactive region; an element structure formed in the active region and including at least an active side p type layer to form pn junction with n type portion of the n type semiconductor layer; an inactive side p type layer formed in the inactive region and forming pn junction with the n type portion of the n type semiconductor layer; a first electrode electrically connected to the active side p type layer in a front surface of the n type semiconductor layer; a second electrode electrically connected to the n type portion of the n type semiconductor layer in a rear surface of the n type semiconductor layer; and a crystal defect region formed in both the active region and the inactive region and having different depths in the active region and the inactive region.