Trench Diode with Lateral Insulation for Fast Recovery
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Solution Overview
Problem
Existing diodes in multi-component devices, such as those used in BCD technology, face challenges in reducing recovery time due to charge storage, leading to potential failure during fast voltage variations and current recirculation phenomena, where traditional methods like ion implantation spread contaminants or increase leakage currents.
Innovation Solution
A diode design featuring a semiconductor body with a trench and lateral insulation region, where the trench surrounds part of the semiconductor body and is filled with dielectric material, reducing charge storage and recovery time by minimizing semiconductor regions that accumulate charge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional diode design is used, then manufacturing is simpler, but recovery time is longer and charge storage is higher
Solution Approach 1:
The diode structure is segmented by introducing a trench that divides the semiconductor body into distinct regions. The trench separates the first semiconductor region from the second semiconductor region, creating isolated charge storage zones that can be independently controlled. This segmentation reduces overall charge storage and accelerates recovery time by preventing charge accumulation in continuous semiconductor paths.
Solution Approach 2:
The invention transitions from a planar diode structure to a three-dimensional structure by introducing a vertical trench. This dimensional change creates lateral insulation regions that extend into the semiconductor body, providing charge isolation in the vertical dimension. The trench depth and positioning create new spatial relationships that reduce charge storage volume while maintaining electrical functionality.
2Loss of time
If ion implantation is used to reduce recovery time, then recovery time decreases, but contaminants spread and leakage currents increase
Solution Approach 1:
The invention extracts the charge storage function from the bulk semiconductor material by introducing a trench that removes a portion of the semiconductor body. This extraction creates lateral insulation regions that isolate charge carriers, reducing recovery time without requiring ion implantation. The removed semiconductor material is replaced with dielectric material that provides insulation without introducing contaminants or increasing leakage currents.
Solution Approach 2:
The trench filled with dielectric material acts as an intermediary structure between the first and second semiconductor regions. This intermediate element provides lateral insulation and charge isolation without direct contact between the semiconductor regions, preventing charge leakage while maintaining electrical isolation. The dielectric material serves as a mediator that achieves charge control without the harmful effects of ion implantation.
3Power
If semiconductor regions are increased to improve current handling, then current capacity increases, but charge storage increases and recovery time lengthens
Solution Approach 1:
The diode structure segments the current path into distinct regions separated by the trench. The first semiconductor region handles current in one direction while the second semiconductor region handles current in the opposite direction. This segmentation allows each region to be optimized for current handling without requiring excessive semiconductor material, as the trench prevents charge accumulation that would otherwise require larger regions to manage.
Solution Approach 2:
The invention applies local quality by creating regions with different properties: the first semiconductor region has properties optimized for forward conduction, the second semiconductor region has properties optimized for reverse conduction, and the trench region has insulating properties. This local differentiation allows each region to perform its function efficiently with minimal charge storage, improving current handling capacity without increasing overall charge storage.
Data Source
AI summary
A diode comprising a semiconductor body delimited by a front surface and including: a first semiconductor region having a first type of conductivity, facing at least in part the front surface; and a second semiconductor region having a second type of conductivity, the second semiconductor region facing at least in part the front surface and surrounding, at a distance, at least part of the first semiconductor region. The diode further includes: a trench, which extends in the semiconductor body starting from the front surface, for surrounding at least part of the second semiconductor region; and a lateral insulation region, which is arranged within the trench, is formed by dielectric material and contacts at least in part the second semiconductor region.