Schottky Source-Drain Contacts for Power Transistor SOA
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Solution Overview
Problem
Conventional power transistors face limitations in safe operating area (SOA) due to parasitic bipolar transistor activation, leading to destructive failures and increased on-state resistance, which complicates device design and increases costs.
Innovation Solution
The introduction of Schottky or Schottky-like contacts as source and/or drain regions in power transistors, eliminating parasitic n-p-n bipolar transistors and reducing device size, while providing improved electrical coupling through interfacial dopant segregation layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional power transistor structures are used, then the device can operate with standard design, but parasitic bipolar transistor activation occurs leading to destructive failures and increased on-state resistance
Solution Approach 1:
The patent extracts and eliminates the parasitic bipolar transistor structure by replacing the conventional p-n junction contact with a Schottky contact. This removes the harmful n-p-n bipolar transistor formation at the contact region, preventing parasitic bipolar activation and improving safe operating area without adding structural complexity
Solution Approach 2:
The patent changes the contact structure parameter from a p-n junction (conventional contact) to a Schottky contact (metal-semiconductor junction). This parameter change fundamentally alters the electrical characteristics, eliminating parasitic bipolar transistor formation while reducing on-state resistance and improving device reliability
2Reliability
If maximum rated operating voltage is set with safety margin below breakdown voltage, then device reliability improves, but on-state resistance increases limiting efficiency
Solution Approach 1:
The patent converts the previously harmful parasitic bipolar transistor structure into a beneficial Schottky contact structure. The Schottky contact eliminates parasitic bipolar activation while enabling the device to operate closer to breakdown voltage with reduced on-state resistance, thus improving both reliability and power efficiency simultaneously
3Reliability
If deep p+ regions or recessed contact structures are introduced to alleviate SOA limitation, then safe operating area improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the problematic parasitic bipolar structure and replaces it with a simple Schottky contact. This eliminates the need for additional deep p+ regions or recessed contact structures, achieving improved safe operating area while maintaining simple manufacturing processes
Solution Approach 2:
The patent changes the contact type parameter to Schottky contact, which inherently provides improved safe operating area characteristics without requiring additional manufacturing steps such as deep implantation or recessed structure formation, thus maintaining ease of manufacture
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 enhances the safe operating area, reduces on-state resistance, and decreases the likelihood of catastrophic failures, resulting in more reliable and efficient power transistors with reduced manufacturing complexity and cost.
Implementation Method 1
at least one of the source region and the drain region is a Schottky or Schottky-like contact
Implementation Method 2
an interfacial dopant segregation layer, wherein the interfacial dopant segregation layer is substantially near the gate structure to provide electrical coupling to the gate and channel region
Data Source
AI summary
Devices, structures, and methods thereof for providing a Schottky or Schottky-like contact as a source region and/or a drain region of a power transistor are disclosed. A power transistor structure comprises a substrate of a first dopant polarity, a drift region formed on or within the substrate, a body region formed on or within the drift region, a gate structure formed on or within the substrate, a source region adjacent to the gate structure, a drain region formed adjacent to the gate structure. At least one of the source region and the drain region is formed from a Schottky or Schottky-like contact substantially near a surface of the substrate, comprising a silicide layer and an interfacial dopant segregation layer. The Schottky or Schottky-like contact is formed by low-temperature annealing a dopant segregation implant in the source and/or drain region.