IGBT Peripheral Region Breakdown Strength via Local Quality
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional semiconductor devices face a trade-off between dielectric breakdown strength and electrical resistance, where increasing dielectric breakdown strength in the peripheral region leads to higher on-voltage in IGBTs, and decreasing it results in lower breakdown strength, posing a challenge in enhancing both without increasing resistance.
Innovation Solution
The semiconductor device design includes a peripheral region with a thicker drift layer and a buffer layer of higher impurity concentration than the active region, along with a guard ring structure, to enhance dielectric breakdown strength without increasing on-voltage, by suppressing carrier injection into the peripheral region and maintaining sufficient carrier injection into the active region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the semiconductor layer is increased to improve dielectric breakdown strength, then the dielectric breakdown strength improves, but the electrical resistance while conducting increases
Solution Approach 1:
The patent applies local quality by differentiating the drift layer thickness between the peripheral region and the active region. Specifically, the drift layer in the peripheral region is made thicker than in the active region, allowing the peripheral region to achieve higher dielectric breakdown strength while the active region maintains lower electrical resistance for efficient conduction. This spatial differentiation resolves the contradiction by optimizing each region for its specific function.
2Reliability
If the thickness of the drift layer in the peripheral region is increased to improve dielectric breakdown strength, then breakdown strength improves, but on-voltage increases
Solution Approach 1:
The invention implements local quality by creating a non-uniform drift layer thickness distribution where the peripheral region has a greater thickness than the active region. This allows the peripheral region to withstand higher voltages and prevent breakdown, while the thinner active region maintains low on-voltage for efficient power switching. The buffer layer with higher impurity concentration further supports this by providing additional voltage resistance in the peripheral region without affecting the active region's conduction characteristics.
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 improves dielectric breakdown strength in the peripheral region without increasing on-resistance, ensuring that breakdown events occur more readily in the active region, thus preventing semiconductor destruction and maintaining device integrity.
Implementation Method 1
the buffer layer... by suppressing carrier injection into the peripheral region
Implementation Method 2
prevent the depletion layer from extending to the collector layer
Implementation Method 3
electric field concentration in the peripheral region is reduced, and the dielectric breakdown strength of the semiconductor device improves
Data Source
AI summary
To provide a semiconductor device in which dielectric breakdown strength in a peripheral region is increased without increasing on-resistance. An IGBT comprises a body region, guard ring, and collector layer. The body region is formed within an active region in a surface layer of a drift layer. The guard ring is formed within a peripheral region in the surface layer of the drift layer, and surrounds the body region. The collector layer is formed at a back surface side of the drift layer, and is formed across the active region and the peripheral region. A distance F between a back surface of the guard ring and the back surface of the drift layer is greater than a distance between a back surface of the body region and the back surface of the drift layer. A thickness H of the collector layer in the peripheral region is smaller than a thickness D of the collector layer in the active region.