Imbalanced Superjunction Structure for UIS Performance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Previous superjunction semiconductor devices face challenges in unclamped inductive switching (UIS) performance due to low snapback current, leading to electrical failures and inadequate energy capability, while maintaining the trade-off between on-state resistance (Rdson) and breakdown voltage (BVdss).
Innovation Solution
The implementation of an imbalanced superjunction structure through ion implantation or intrinsic-epitaxial dopant profile tailoring creates a non-uniform electric field distribution, delaying negative differential resistance and increasing snapback current, thereby enhancing UIS performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If superjunction devices are designed with optimum charge balance to improve breakdown voltage, then BVdss increases, but UIS performance deteriorates due to low snapback current
Solution Approach 1:
The patent applies local quality by creating a non-uniform dopant distribution within the superjunction structure. Specifically, the dopant concentration is varied along the vertical depth of the drift region, with higher concentration near the surface and lower concentration deeper in the structure. This localized variation in dopant quality enables different regions to serve different functions: the upper region provides higher snapback current for improved UIS performance, while the lower region maintains the charge balance needed for high breakdown voltage.
Solution Approach 2:
The patent employs parameter changes by modifying the dopant concentration parameter as a function of depth within the semiconductor structure. The dopant concentration is intentionally made non-uniform, transitioning from higher values near the surface to lower values at greater depths. This parameter variation allows the structure to achieve both improved snapback current (through higher surface concentration) and maintained breakdown voltage (through appropriate deeper concentration), thereby resolving the contradiction between UIS performance and breakdown voltage.
2Loss of energy
If heavily doped n-type and p-type regions are used to lower on-state resistance, then Rdson decreases, but UIS performance worsens due to reduced snapback current
Solution Approach 1:
The patent applies local quality by creating a non-uniform dopant distribution within the superjunction structure. Specifically, the dopant concentration is varied along the vertical depth of the drift region, with higher concentration near the surface and lower concentration deeper in the structure. This localized variation in dopant quality enables different regions to serve different functions: the upper region provides higher snapback current for improved UIS performance, while the lower region maintains the charge balance needed for high breakdown voltage.
Solution Approach 2:
The patent employs parameter changes by modifying the dopant concentration parameter as a function of depth within the semiconductor structure. The dopant concentration is intentionally made non-uniform, transitioning from higher values near the surface to lower values at greater depths. This parameter variation allows the structure to achieve both improved snapback current (through higher surface concentration) and maintained breakdown voltage (through appropriate deeper concentration), thereby resolving the contradiction between UIS performance and breakdown voltage.
3Strength
If charge balance is optimized to improve breakdown voltage, then BVdss increases, but energy capability deteriorates due to low snapback current
Solution Approach 1:
The patent applies local quality by creating a non-uniform dopant distribution within the superjunction structure. Specifically, the dopant concentration is varied along the vertical depth of the drift region, with higher concentration near the surface and lower concentration deeper in the structure. This localized variation in dopant quality enables different regions to serve different functions: the upper region provides higher snapback current for improved UIS performance, while the lower region maintains the charge balance needed for high breakdown voltage.
Solution Approach 2:
The patent employs parameter changes by modifying the dopant concentration parameter as a function of depth within the semiconductor structure. The dopant concentration is intentionally made non-uniform, transitioning from higher values near the surface to lower values at greater depths. This parameter variation allows the structure to achieve both improved snapback current (through higher surface concentration) and maintained breakdown voltage (through appropriate deeper concentration), thereby resolving the contradiction between UIS performance and breakdown voltage.
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 approach results in improved UIS robustness and energy capability, with increased snapback current and breakdown voltage, while maintaining the design trade-offs between Rdson and BVdss without significant process complexity or cost.
Implementation Method 1
The implementation of an imbalanced superjunction structure through ion implantation or intrinsic-epitaxial dopant profile tailoring creates a non-uniform electric field distribution
Implementation Method 2
creates a non-uniform electric field distribution, delaying negative differential resistance and increasing snapback current
Data Source
AI summary
In one embodiment, a semiconductor substrate is provided having a localized superjunction structure extending from a major surface. A doped region is then formed adjacent the localized superjunction structure to create a charge imbalance therein. In one embodiment, the doped region can be an ion implanted region formed within the localized superjunction structure. In another embodiment, the doped region can be an epitaxial layer having a graded dopant profile adjoining the localized superjunction structure. The charge imbalance can improve, among other things, unclamped inductive switching (UIS) performance.