Termination Region Insulating Structure for High Voltage Reliability
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Solution Overview
Problem
High voltage electronic devices face issues with mobile ions migrating from molding compounds into epitaxial silicon layers, affecting drain-to-source breakdown voltage, and existing solutions like field plates and trenches introduce process complexity and yield reduction.
Innovation Solution
A termination region with insulating regions extending less than 50% of the semiconductor layer thickness and a field electrode overlying the semiconductor layer, along with a process of forming trenches and insulating layers to reduce the termination region's area and enhance voltage handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a field plate is placed over the epitaxial silicon layer to protect it from mobile ions, then the protection against mobile ions is improved, but the device complexity and process complexity increase
Solution Approach 1:
The patent extracts the protection function from a separate field plate structure and integrates it into the termination region's oxide layer. The oxide layer is formed as part of the termination region fabrication process itself, eliminating the need for additional field plate deposition and associated complex processes while maintaining the protective function against mobile ions.
Solution Approach 2:
The patent merges the protective oxide layer with the termination region structure. The oxide layer is formed concurrently with termination region features during the same fabrication process, combining the protection function with the existing termination region fabrication steps, thereby reducing overall process complexity.
2Reliability
If a trench is formed through more than 50% of the epitaxial silicon layer thickness to protect from mobile ions, then the protection against mobile ions is improved, but the device complexity and yield are adversely affected
Solution Approach 1:
The patent applies partial action by forming oxide regions that extend into the epitaxial silicon layer but limit their depth to less than 50% of the layer thickness. This partial penetration provides sufficient protection against mobile ions while avoiding the excessive trench depth that would compromise yield and increase process complexity.
Solution Approach 2:
The patent changes the parameter of oxide region depth from the conventional deep trench approach (through or beyond 50% thickness) to a shallow oxide approach (less than 50% thickness). This parameter change maintains protective functionality while significantly improving yield and reducing process complexity.
3Area of stationary object
If the termination region area is reduced by 50%, then the area efficiency is improved, but the voltage handling capability may be compromised
Solution Approach 1:
The patent applies local quality by creating oxide regions with specific localized depths and positions within the termination region. The oxide extends into the epitaxial silicon layer at critical locations where mobile ion intrusion would most affect transistor performance, providing enhanced protection in high-stress areas while maintaining overall area reduction.
Solution Approach 2:
The patent transitions from a two-dimensional area-based termination region to a three-dimensional structure with vertical oxide regions extending into the epitaxial silicon layer. This dimensional change allows the termination region to maintain reduced planar area while providing enhanced voltage handling through the added vertical protection dimension.
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 solution reduces the termination region's area by 50% and allows for higher voltage operation without increasing area, while maintaining a more planar device structure and improving yield by integrating with transistor formation processes.
Implementation Method 1
Mobile ions may migrate from the molding compound into an epitaxial silicon layer within the termination region
Implementation Method 2
The field plate is separated from the epitaxial silicon layer by a thick oxide layer
Data Source
AI summary
An electronic device can include an electronic component and a termination region adjacent to the electronic component region. In an embodiment, the termination region can include an insulating region that extends a depth into a semiconductor layer, wherein the depth is less than 50% of the thickness of the semiconductor layer. In another embodiment, the termination region can include a first insulating region that extends a first depth into the semiconductor layer, and a second insulating region that extends a second depth into the semiconductor layer, wherein the second depth is less than the first depth. In another aspect, a process of forming an electronic device can include patterning a semiconductor layer to define a trench within termination region while another trench is being formed for an electronic component within an electronic component region.