Power Semiconductor Wafer with Dielectric Liquid Insulation
Solution Overview
Problem
Current power semiconductor devices are not tolerant against high hydrostatic external pressure or high vacuum environments, as they lack mechanical stability when immersed in water or exposed to high vacuum conditions, leading to dielectric breakdown and loss of blocking capability.
Innovation Solution
A power semiconductor device comprising a semiconductor wafer with a passivated junction termination surrounded by an isolating medium such as a dielectric liquid, pressurized dielectric gas, or vacuum, which provides mechanical stability and prevents dielectric breakdown, allowing the device to operate in high hydrostatic pressure and high vacuum environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the semiconductor wafer is mounted in a copper-ceramic housing with thin flanges, then the device can be packaged and protected, but the housing lacks mechanical stability under high hydrostatic pressure or high vacuum
Solution Approach 1:
The invention removes the housing structure entirely, extracting the problematic thin flanges that lacked mechanical stability. The semiconductor wafer is used directly without encapsulation in a copper-ceramic housing, eliminating the source of mechanical instability while maintaining electrical functionality through direct mounting between coolers or within modules.
Solution Approach 2:
Instead of protecting the semiconductor wafer with a housing that proves mechanically weak, the invention inverts the approach by using the semiconductor wafer itself as the structural element and relying on the external medium (dielectric liquid, pressurized gas, or vacuum) and mounting structure (coolers/modules) to provide both electrical insulation and mechanical support.
2Ease of operation
If the junction termination is exposed to air or nitrogen, then the device can operate, but the dielectric strength is insufficient (E max ≤30 kV/cm) leading to dielectric breakdown at high electric fields
Solution Approach 1:
The invention changes the dielectric parameter (dielectric strength) by replacing air or nitrogen with a dielectric liquid or pressurized dielectric gas that has higher dielectric strength. This parameter change allows the junction termination to withstand higher electric fields without breakdown, improving blocking capability while maintaining operability.
Solution Approach 2:
The invention creates an inert environment using dielectric liquid or pressurized dielectric gas that prevents dielectric breakdown. The inert medium surrounds and protects the junction termination, preventing harmful electrical discharge while allowing the device to operate normally.
3Strength
If the semiconductor wafer is used without housing in dielectric liquid or pressurized gas, then mechanical stability under high pressure and vacuum is improved, but additional materials must be compatible with the dielectric medium
Solution Approach 1:
The invention changes the operating environment parameter by selecting dielectric liquids or pressurized dielectric gases that are chemically compatible with the semiconductor wafer and mounting structures. This parameter selection ensures both mechanical stability under high pressure/vacuum and material compatibility, resolving the contradiction between improved strength and adaptability.
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 semiconductor device remains functional and maintains blocking capability in high hydrostatic pressure and high vacuum conditions, enabling its use in applications like subsea converters and high vacuum power generation systems without the need for a housing, ensuring creepage and strike distance requirements are met.
Implementation Method 1
an isolating medium selected from the group consisting of a dielectric liquid, a pressurized dielectric gas and a vacuum
Implementation Method 2
When the p-n junction reaches a surface of the power semiconductor device and the electric field exceeds a dielectric strength E max of an ambient dielectric, such as air, nitrogen, vacuum, oil etc., the dielectric breakdown occurs. The high electric field ionizes molecules and changes them from an insulator to a conductor.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a power semiconductor device, comprising a semiconductor wafer (1) having at least contact element (2) and a passivated junction termination (3) laterally surrounding the at least one contact element (2), and an insulating medium (4) selected from the group consisting of a dielectric liquid, a pressurized dielectric gas and a vacuum, wherein the semiconductor wafer (1) is surrounded by the insulating medium (4).