Semiconductor Termination Region with Asymmetric Pillar Structures
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Solution Overview
Problem
Forming p-type and n-type pillar layers with a super junction structure on a semiconductor substrate with an off-angle is challenging, as it is difficult to create pillar layers extending in directions other than the step-flow direction, making it hard to achieve a termination region with surrounding pillar layers in semiconductor devices.
Innovation Solution
A semiconductor device with a drift layer and pillar regions formed on an off-angle substrate, where the p-type pillar regions have a linear shape extending in the step-flow direction, and withstand voltage holding structures with a frame-like shape are formed to surround the active region, reducing local electrical field concentration and resistance while maintaining high voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If p-type and n-type pillar layers are formed to surround the active region in the termination region, then withstand voltage is improved, but manufacturing difficulty increases due to substrate off-angle constraints
Solution Approach 1:
The patent applies asymmetry by forming pillar layers only on three sides of the active region rather than all four sides. This asymmetric configuration adapts to the substrate's off-angle characteristics and step-flow growth direction, making manufacturing feasible while still achieving sufficient withstand voltage through strategic placement of depletion layers where they are most effective
Solution Approach 2:
The patent implements local quality by concentrating pillar layer formation in specific regions (three sides surrounding the active region) rather than uniformly across all peripheries. This localized approach targets areas where voltage holding is most critical while avoiding manufacturing challenges in other regions, optimizing both performance and manufacturability
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 solution reduces electrical field concentration and resistance in the termination region, allowing for high withstand voltage and low ON resistance in semiconductor devices, even with high impurity concentrations in the drift layer.
Implementation Method 1
In an epitaxial growth on the semiconductor substrate having the off-angle, a growth in a lateral direction occurs from a difference in level between atomic planes. The growth in the lateral direction is called a 'step-flow growth' and a direction of the growth is called a 'step-flow direction'.
Data Source
AI summary
A semiconductor device includes an n-type drift layer formed on a semiconductor substrate having an off-angle, plurality of p-type pillar regions formed in the drift layer, and a surface electrode formed on the drift layer including the plurality of p-type pillar regions. A plurality of withstand voltage holding structures which are p-type semiconductor regions are formed in a surface layer of the drift layer including the plurality of p-type pillar regions to surround an active region. Each of the plurality of p-type pillar regions has a linear shape extending in a direction of the off-angle of the semiconductor substrate. Each of the plurality of withstand voltage holding structures has a frame-like shape including sides extending in parallel with the plurality of p-type pillar regions and sides perpendicular to the plurality of p-type pillar regions in a planar view.