High-Voltage Semiconductor Isolation Structure Prevents Leakage
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Solution Overview
Problem
Conventional high-voltage semiconductor devices experience current leakage due to signals transmitted from the low-voltage unit to the high-voltage unit without going through the level-shift unit, leading to reduced breakdown voltage.
Innovation Solution
A high-voltage semiconductor device design featuring a substrate with an epitaxial layer, a high-voltage unit, a low-voltage unit, and a level-shift unit, where the level-shift unit includes a source and drain region with a gate electrode, and an isolation structure is disposed between the high-voltage and low-voltage units to prevent current leakage by electrically separating them.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If signals are transmitted directly from the low-voltage unit to the high-voltage unit without going through the level-shift unit, then the device complexity is reduced, but current leakage occurs and breakdown voltage is reduced
Solution Approach 1:
The patent introduces an isolation structure as an intermediary element positioned between the low-voltage unit and high-voltage unit. This isolation structure acts as a mediator that blocks direct signal transmission while allowing controlled electrical connection through the level-shift unit, thereby preventing current leakage paths while maintaining the intended signal flow through proper voltage level shifting.
Solution Approach 2:
The patent segments the electrical connection between low-voltage and high-voltage units by introducing the isolation structure. This segmentation separates the direct electrical path into two distinct paths: one through the isolation structure (blocked) and another through the level-shift unit (controlled), allowing independent optimization of each path's function.
2Reliability
If an isolation structure is added between the high-voltage unit and low-voltage unit, then current leakage is prevented and breakdown voltage is maintained, but the device complexity increases
Solution Approach 1:
The patent merges multiple functions into the isolation structure: it provides electrical isolation to prevent current leakage, maintains breakdown voltage, and still allows controlled signal transmission through its capacitive coupling. By combining these functions into a single structure rather than adding separate components, the overall device complexity is minimized while achieving the desired reliability improvement.
Solution Approach 2:
The isolation structure serves multiple functions simultaneously: it acts as an electrical barrier to prevent leakage currents, maintains the breakdown voltage characteristic, and enables capacitive coupling for signal transmission. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.
3Adaptability or versatility
If the level-shift unit is properly designed with source, drain, and gate regions, then voltage level shifting is achieved, but the device size increases
Solution Approach 1:
The level-shift unit is designed with nested regions where the gate electrode is positioned between the source and drain regions, and these regions are integrated within the epitaxial layer structure. This nested arrangement allows multiple functional regions to occupy overlapping or adjacent spaces, reducing the overall footprint of the voltage level shifting mechanism.
Solution Approach 2:
The patent utilizes vertical stacking in the epitaxial layer to accommodate the source, drain, and gate regions of the level-shift unit. By transitioning from a planar layout to a three-dimensional arrangement where regions are stacked vertically rather than only arranged horizontally, the device achieves voltage level shifting functionality with reduced planar footprint.
Data Source
AI summary
High-voltage semiconductor devices are provided. The high-voltage semiconductor device includes a substrate having a first conductive type and an epitaxial layer having a second conductive type disposed on the substrate. The epitaxial layer includes a high-voltage unit, a low-voltage unit disposed around the high-voltage unit and a level-shift unit disposed between the high-voltage unit and the low-voltage unit. The level-shift unit includes a source region, a drain region having disposed between the source region and the high-voltage unit, wherein the drain region is electrically connected to the high-voltage unit by a drain electrode disposed above the drain region. The level unit includes a gate electrode disposed between the source region and the drain region. The high-voltage semiconductor device also includes an isolation structure disposed between the high-voltage unit and the low-voltage unit, and the isolation structure is disposed directly under the drain electrode.