Drift Layer Energy Level Layout for Diode Reverse Recovery
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Solution Overview
Problem
Existing semiconductor devices face challenges in improving the reverse recovery characteristics of built-in diodes, particularly in controlling carrier lifetime effectively without causing defects in the gate insulating films and affecting insulation reliability.
Innovation Solution
A semiconductor device design with a silicon layer having a mesa part and a buried electrode part, where energetic particles are irradiated through a film thickness difference in the upper electrode to create a higher energy level density in the first region under the mesa part, reducing reverse recovery charge without affecting the buried electrode part, thereby enhancing reverse recovery characteristics while preventing defects in insulating films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-energy particles are irradiated to control carrier lifetime in the drift layer, then reverse recovery characteristics are improved, but defects are caused in gate insulating films affecting insulation reliability
Solution Approach 1:
The patent applies local quality by creating distinct energy level densities in different regions: the first region (drift layer under mesa part) has high energy level density for carrier lifetime control, while the second region (drift layer under buried electrode part) has low energy level density to prevent defects. This spatial differentiation allows selective improvement of reverse recovery characteristics without compromising gate insulating film reliability.
Solution Approach 2:
The drift layer is segmented into two distinct regions with different energy level densities. The first region is targeted for irradiation to control carrier lifetime, while the second region is protected from irradiation effects. This segmentation enables independent optimization of reverse recovery characteristics and insulation reliability in different spatial zones.
2Reliability
If uniform energy level density is created throughout the drift layer, then carrier lifetime is controlled, but reverse recovery charge cannot be sufficiently reduced without affecting insulation reliability
Solution Approach 1:
Instead of uniform energy level density, the patent implements non-uniform distribution with high density in the first region and low density in the second region. This local quality approach enables effective reduction of reverse recovery charge through targeted carrier lifetime control in the first region while maintaining insulation reliability through protected second region.
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 reverse recovery characteristics of the built-in diode by locally forming energy levels in the drift layer under the mesa part, reducing reverse recovery charge without causing defects in the insulating films, resulting in a highly reliable semiconductor device with simplified processes and no need for annealing.
Implementation Method 1
energetic particles are irradiated through a film thickness difference in the upper electrode to create a higher energy level density in the first region under the mesa part
Data Source
AI summary
A semiconductor device includes an upper electrode; a lower electrode; a substrate positioned between the upper electrode and the lower electrode; a buried electrode part positioned between the substrate and the upper electrode, the buried electrode part including a gate electrode; and a silicon layer positioned between the substrate and the upper electrode. The silicon layer includes a mesa part next to the buried electrode part, a first region positioned between the mesa part and the substrate, and a second region positioned between the buried electrode part and the substrate. An energy level density of the first region is greater than an energy level density of the second region.