Two-Stage Field Stop Zone in Bipolar Power Components
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Solution Overview
Problem
Bipolar power components, such as power diodes and IGBTs, face challenges in minimizing the current gradient during the turn-off phase due to parasitic leakage inductances, which are induced by voltage fluctuations, and existing methods for creating stop zones in semiconductor bodies are inefficient in achieving a gentle turn-off operation.
Innovation Solution
A method involving proton irradiation followed by a thermal annealing process to create a two-stage field stop zone, where the first region is heavily doped and the second region is more weakly doped, with the second region acting as a 'plasma reservoir' to maintain a sufficient charge carrier concentration and reduce current gradient during the turn-off operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-stage stop zone is used to limit the electric field in the base zone, then the punch-through prevention is achieved, but the turn-off phase exhibits a high current gradient due to insufficient charge carrier maintenance
Solution Approach 1:
The stop zone is divided into two distinct regions: a first stop zone region with higher doping concentration for electric field limitation and punch-through prevention, and a second stop zone region with lower doping concentration that serves as a plasma reservoir. This segmentation allows each region to fulfill specific functions, resolving the contradiction between reliable electric field control and gentle turn-off behavior.
Solution Approach 2:
Different doping concentrations are applied to different regions of the stop zone. The first region has higher doping for field limitation, while the second region has lower doping to maintain charge carriers. This local differentiation of properties enables simultaneous achievement of punch-through prevention and reduced current gradient during turn-off.
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
The method effectively produces a two-stage field stop zone that ensures a gentle turn-off behavior by maintaining a sufficient charge carrier plasma throughout the turn-off operation, reducing the current gradient and minimizing parasitic leakage inductances, thereby enhancing the performance of bipolar power components.
Implementation Method 1
irradiating the semiconductor body via one of the sides with protons, as a result of which protons are introduced into a first region of the semiconductor body
Implementation Method 2
A thermal process is subsequently carried out in which the semiconductor body is heated to a predetermined temperature for a predetermined time duration
Implementation Method 3
the protons diffuse from the first region, so that hydrogen-induced donors, the formation of which requires the defects caused by irradiation
Data Source
AI summary
A method for producing a buried stop zone in a semiconductor body and a semiconductor component having a stop zone, the method including providing a semiconductor body having a first and a second side and a basic doping of a first conduction type. The method further includes irradiating the semiconductor body via one of the sides with protons, as a result of which protons are introduced into a first region of the semiconductor body situated at a distance from the irradiation side. The method also includes carrying out a thermal process in which the semiconductor body is heated to a predetermined temperature for a predetermined time duration, the temperature and the duration being chosen such that hydrogen-induced donors are generated both in the first region and in a second region adjacent to the first region in the direction of the irradiation side.