Deep Trench Isolation With Buried Layers for Latch-Up Suppression
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Solution Overview
Problem
Conventional methods to prevent latch-up effect in semiconductor devices require increasing the distance between PN junctions or the size of isolation structures, which contradicts the need for reducing the size of semiconductor devices, especially at higher operating voltages.
Innovation Solution
A semiconductor device with a deep trench isolation structure and buried layers that reduce parasitic bipolar transistor effects, allowing for increased operating voltage without increasing device size, using a substrate with first and second buried layers and a deep trench isolation structure that surrounds well regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the distance between PN junctions is increased to prevent latch-up effect, then the reliability is improved, but the device size increases
Solution Approach 1:
The patent introduces a vertical dimension by forming a deep trench isolation structure that extends deeply into the substrate. This vertical isolation approach separates the p-type and n-type well regions in the depth direction rather than relying solely on horizontal distance, thereby preventing latch-up effect without increasing the lateral device footprint
Solution Approach 2:
The isolation structure is segmented into multiple components including a deep trench isolation structure, first and second buried layers with different conductivity types, and well regions. This segmentation allows for targeted electrical isolation between PN junctions while maintaining compact device dimensions
2Reliability
If the size of isolation structure at PN junction is increased to prevent latch-up effect, then the reliability is improved, but the device size increases
Solution Approach 1:
Instead of increasing the lateral size of isolation structures at PN junctions, the patent extends the isolation structure vertically by forming a deep trench that penetrates deeply into the substrate. This vertical extension provides effective electrical isolation without occupying additional lateral device area
Solution Approach 2:
The patent changes the key parameter of the isolation structure from lateral dimensions to vertical depth. By increasing the depth of the trench isolation and adjusting the doping concentrations of buried layers, effective isolation is achieved while maintaining compact device dimensions
3Power
If the operating voltage is increased, then the power capability is improved, but the device size must be increased to maintain reliability
Solution Approach 1:
The patent uses vertical extension of the deep trench isolation structure to handle high voltage requirements without increasing lateral device dimensions. The deep trench provides enhanced electrical isolation capable of withstanding high operating voltages while maintaining a compact device footprint
Solution Approach 2:
The patent employs a composite structure combining deep trench isolation with multiple buried layers of different conductivity types (p-type and n-type). This composite approach creates an isolation system capable of withstanding high voltages through the combined effect of physical separation and electrical field management
Data Source
AI summary
A semiconductor device includes a first buried layer and a second buried layer both have a first conductivity type and are disposed in a substrate, where the second buried layer is disposed on the first buried layer. A first well region has the first conductivity type and is disposed above the second buried layer. A second well region has a second conductivity type and is adjacent to the first well region. A deep trench isolation structure is disposed in the substrate and surrounds the first and second well regions, where the bottom surface of the deep trench isolation structure is lower than the bottom surface of the first buried layer. A source region is disposed in the second well region. A drain region is disposed in the first well region. A gate electrode is disposed on the first and second well regions.