Semiconductor Termination Floating Regions for Breakdown Voltage
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Solution Overview
Problem
Semiconductor devices face challenges in maintaining breakdown voltage in the termination region when the impurity concentration of the drift region is high, leading to potential avalanche breakdown due to higher temperature in the termination region.
Innovation Solution
The semiconductor device incorporates a configuration where second floating regions in the termination region are placed closer to the reference depth than first floating regions in the element region, distributing the electric field more evenly and reducing peak electric field intensity, allowing for a higher breakdown voltage in the termination region compared to the element region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the impurity concentration of the drift region is increased to reduce on-resistance, then the on-resistance is reduced, but the breakdown voltage of the termination region decreases
Solution Approach 1:
The patent applies local quality by creating different impurity concentration profiles in different regions. The drift region has high impurity concentration to reduce on-resistance, while the termination region maintains low impurity concentration to preserve breakdown voltage. This spatial differentiation of material properties resolves the contradiction between low on-resistance and high breakdown voltage.
Solution Approach 2:
The semiconductor device is segmented into distinct functional regions: an element region with high impurity concentration drift region for low on-resistance, and a termination region with low impurity concentration for high breakdown voltage. This segmentation allows each region to optimize its electrical characteristics independently, resolving the trade-off between power loss and breakdown voltage.
2Device complexity
If the breakdown voltage of the termination region is set equal to or lower than the element region to simplify design, then the structure is simpler, but avalanche breakdown occurs in the termination region causing high temperature
Solution Approach 1:
The patent implements local quality by assigning different breakdown voltage characteristics to different regions. The termination region is designed with lower impurity concentration to achieve higher breakdown voltage than the element region, preventing avalanche breakdown and the associated temperature rise in the termination region.
3Power
If the impurity concentration of the drift region is increased to improve current handling capability, then the current carrying capacity is improved, but the breakdown voltage decreases leading to avalanche breakdown
Solution Approach 1:
The device is segmented into a power handling element region with high impurity concentration drift region and a termination region with low impurity concentration. This segmentation enables the element region to handle high currents while the termination region maintains high breakdown voltage to prevent avalanche breakdown.
Solution Approach 2:
Different impurity concentrations are applied locally to different regions based on their functional requirements. The element region uses high impurity concentration for maximum current handling, while the termination region uses low impurity concentration for high breakdown voltage protection.
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 configuration effectively maintains a higher breakdown voltage in the termination region even with high impurity concentration, preventing avalanche breakdown and ensuring the semiconductor device can handle larger breakdown currents without overheating.
Implementation Method 1
the reference-depth-side second floating region can more evenly distribute an electric field in the thickness direction of the semiconductor substrate than the first floating regions. Accordingly, a peak value of the electric field intensity of the reference-depth-side second floating region becomes lower than a peak value of the electric field intensity of the first floating regions.
Data Source
AI summary
A semiconductor device includes a semiconductor substrate. The element region of the semiconductor substrate includes a first body region having a first conductivity type, a first drift region having a second conductivity type, and a plurality of first floating regions, each the first floating regions having the first conductivity type. The termination region includes a second drift region having the second conductivity type, and a plurality of second floating regions, each of the second floating regions having the first conductivity type. The each of the second floating regions is surrounded by the second drift region. When a depth of a center of the first drift region is taken as a reference depth, at least one of the second floating regions is placed closer to the reference depth than each of the first floating regions.