Semiconductor Substrate Recess Layout for Higher Breakdown Voltage
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Solution Overview
Problem
Semiconductor devices face challenges in suppressing electric field concentration and improving breakdown voltage due to the design of semiconductor substrates with high-concentration and low-concentration layers, particularly at the boundary between thick and thin plate portions.
Innovation Solution
The semiconductor device incorporates a recess in the peripheral region with a field plate and insulation layers to distribute the depletion layer effectively, ensuring that a half or more of a quadrilateral region remains non-depleted during avalanche breakdown, thereby suppressing electric field concentration and enhancing breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a recess is provided at the upper surface of the semiconductor substrate in the peripheral region, then the upper surface of the semiconductor substrate protrudes in the element region more than in the peripheral region, but electric field concentration occurs at the boundary between thick and thin plate portions
Solution Approach 1:
The patent applies local quality by creating a stepped structure where the high-concentration layer has different thicknesses (thick plate portion in element region, thin plate portion in peripheral region). This localized variation in layer thickness allows the structure to protrude in the element region while maintaining proper electric field distribution through the stepped configuration at the boundary.
Solution Approach 2:
The low-concentration layer acts as an intermediary between the high-concentration layer and the drift layer. It is positioned to contact the side surface of the drift layer, the upper surface of the thin plate portion, and the side surface of the stepped portion, thereby mediating the electric field distribution and preventing concentration at the boundary between thick and thin plate portions.
2Manufacturing precision
If the high-concentration layer has a thin plate portion extending to the peripheral region, then the thickness of the low-concentration layer above the thin plate portion is ensured, but the breakdown voltage of the peripheral region needs improvement
Solution Approach 1:
The patent changes the concentration parameter by introducing a low-concentration layer with lower impurity concentration than the drift layer. This parameter change in the semiconductor structure allows the thin plate portion to maintain proper thickness while the low-concentration layer provides additional breakdown voltage enhancement in the peripheral region.
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 suppresses electric field concentration and improves the breakdown voltage of the semiconductor device by ensuring the thickness of the low-concentration layer above the thin plate portion and distributing the depletion layer to prevent avalanche breakdown.
Implementation Method 1
The drift layer may have a Schottky barrier contact with the upper electrode. The drift layer may be connected to the upper electrode via a p-layer. A diode, for example, a Schottky barrier diode, a p-n diode may be formed between the drift layer and the upper electrode.
Implementation Method 2
ensuring that a half or more of a quadrilateral region remains non-depleted during avalanche breakdown, thereby suppressing electric field concentration and enhancing breakdown voltage
Data Source
AI summary
A semiconductor device includes a semiconductor substrate having an element region and a peripheral region. The semiconductor substrate includes a high-concentration layer, a drift layer, and a low-concentration layer. The high-concentration layer extends from the element region to the peripheral region, and is in contact with a lower electrode. The high-concentration layer has a thin plate portion and a thick plate portion. The drift layer is in contact with the upper surface of the thick plate portion. The low-concentration layer extends from the element region to the peripheral region, and is in contact with an upper surface of the thin plate portion and a side surface of a stepped portion at a boundary between the thin plate portion and the thick plate portion. A half or more of a quadrilateral region in a cross section of the semiconductor substrate is not depleted.