Multi-Trench Isolation with Bias for Power Semiconductor Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Junction isolated smart power technologies face challenges with large lateral isolation structures and high thermal destruction due to thick buried oxides in SOI technologies, which are costly and inefficient for high voltage applications.
Innovation Solution
The implementation of a multi-trench isolation structure with a bias arrangement that divides voltage across isolation trenches, optimizing voltage distribution to enhance reverse breakdown voltage and thermal properties without additional processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If junction isolated smart power technology is used, then manufacturing cost is reduced, but lateral isolation area increases and thermal destruction occurs
Solution Approach 1:
The isolation structure is divided into multiple deep trenches instead of using a single thick buried oxide layer. This segmentation allows voltage to be distributed across multiple isolation regions, reducing the thermal barrier effect while maintaining electrical isolation. The trenches are filled with conductive material and biased to create intermediate potential regions that improve heat dissipation pathways.
Solution Approach 2:
The invention transitions from two-dimensional lateral isolation to three-dimensional vertical isolation using deep trenches extending into the substrate. This dimensional change enables better thermal management by creating vertical heat dissipation pathways while maintaining electrical isolation, solving both the thermal destruction and area consumption problems.
2Reliability
If SOI technology with thick buried oxide is used, then vertical isolation is improved, but thermal diffusivity decreases and device reliability worsens
Solution Approach 1:
The isolation structure uses a composite configuration combining oxide layers in trenches with conductive filling materials. This composite structure provides both electrical isolation through the oxide and thermal conduction through the metal fill, simultaneously achieving vertical isolation and improved thermal diffusivity.
3Reliability
If lateral isolation structures are enlarged to increase blocking voltage, then voltage blocking capability is improved, but device area increases
Solution Approach 1:
The invention achieves higher blocking voltage by extending isolation trenches vertically into the substrate rather than expanding laterally. The deep trenches create multiple isolation barriers at different depths, distributing the voltage blocking function across the vertical dimension and maintaining high packing density.
4Reliability
If highly doped implanted buried layers are used for vertical isolation, then isolation effectiveness is improved, but thermal budget increases
Solution Approach 1:
The isolation function is segmented into multiple deep trenches with conductive fills rather than using a single highly doped buried layer. This segmentation achieves effective electrical isolation through the trench structure while avoiding the high thermal budget requirements of extensive ion implantation and annealing processes.
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 approach improves the reliability, stability, and area efficiency of semiconductor devices by maximizing breakdown voltage while reducing thermal destruction and costs, competing with SOI technologies in high-temperature applications.
Implementation Method 1
a bias arrangement coupled to the regions and arranged to divide a voltage across the isolation structure between the two or more isolation trenches
Implementation Method 2
Technologies processed on SOI (Silicon on Insulator) use trench isolation, guaranteeing both lateral and vertical isolation through oxide layers
Implementation Method 3
in order to reduce the effect of the back-gate effect (substrate potential), the buried oxide needs to be thick
Implementation Method 4
a thick oxide poses a barrier to the heat generated in a power switch due to the much lower thermal diffusivity in oxide compared to silicon
Data Source
AI summary
An integrated power semiconductor device has an isolation structure having two or more isolation trenches, and one or more regions in between the isolation trenches, and a bias arrangement coupled to the regions to divide a voltage across the isolation structure between the isolation trenches. By dividing the voltage, the reverse breakdown voltage characteristics such as voltage level, reliability and stability can be improved for a given area of device, or for a given complexity of device, and avalanche breakdown at weaknesses in isolation structures can be reduced or avoided.