Radiation-Hardened Power MOSFET Drift Layer for Single-Event Burnout
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Solution Overview
Problem
Conventional semiconductor power devices, such as silicon carbide (SiC) MOSFETs, are susceptible to single event effects and failure at high blocking voltages due to radiation intolerance, leading to device failure during radiation events like ion strikes, which existing solutions attempt to address but result in increased on-state resistance losses and complexity.
Innovation Solution
A radiation hardened semiconductor power device is designed with a heavily doped and thick drift layer, maintaining a doping concentration between 1×10^15 cm^-3 and 1.5×10^16 cm^-3 and a thickness of 15µm to 200µm, allowing the device to block high voltages while minimizing on-state resistance losses and surviving radiation events with less than 80% drift layer depletion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the drift layer is made thicker and more heavily doped to reduce on-state resistance losses, then the device performance improves, but the device becomes more susceptible to radiation effects and single event burnout
Solution Approach 1:
The patent applies parameter changes by optimizing the drift layer doping concentration to a specific range (1×10^15 cm^-3 to 1.5×10^16 cm^-3) and controlling the thickness (15µm to 200µm) to achieve a balance between reducing on-state resistance losses and maintaining radiation hardness. This specific parameter optimization allows the device to withstand radiation events while minimizing energy losses during operation.
Solution Approach 2:
The patent employs partial action by ensuring the drift layer is not completely depleted during radiation events, maintaining less than 80% drift layer depletion. This partial depletion approach provides a safety margin that prevents single event burnout while still allowing the device to block high voltages effectively, thus improving reliability without significantly compromising energy efficiency.
2Loss of energy
If the drift layer doping concentration is increased to reduce on-state resistance, then conduction losses decrease, but the device fails at high blocking voltages due to radiation intolerance
Solution Approach 1:
The patent resolves this contradiction through precise parameter changes by establishing an optimal doping concentration range (1×10^15 cm^-3 to 1.5×10^16 cm^-3) that simultaneously reduces conduction losses and improves radiation tolerance. This optimized parameter range allows the device to maintain low on-state resistance while withstanding radiation exposure and high blocking voltages without failure.
3Reliability
If existing solutions are implemented to address radiation effects, then device reliability under radiation improves, but on-state resistance losses and device complexity increase
Solution Approach 1:
The patent avoids increasing device complexity by focusing on parameter optimization rather than adding structural elements. By adjusting the drift layer doping concentration and thickness within specific ranges, the patent achieves improved radiation survival without introducing additional layers or complex structures, thus maintaining manufacturing simplicity and cost-effectiveness.
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 effectively balances high voltage blocking capability with reduced on-state resistance losses and cost-effectiveness by ensuring the drift layer is not completely depleted during radiation events, enhancing the device's radiation hardness and manufacturing efficiency.
Implementation Method 1
an electrical field profile in the drift layer extends less than 80% of the thickness of the drift layer
Implementation Method 2
susceptible to at least single event effects, and in particular to single event burnout and subject to failure at high blocking voltages due to radiation intolerance
Data Source
Figure 1A~1B
Figure 2A
Figure 2B
AI summary
A radiation hardened semiconductor device (100) including a heavily doped substrate (106) of a semiconductor device (100), a drift layer (104) having a substantially uniform doping concentration and a thickness is provided. The doping concentration and the thickness of the drift layer (104) are such that when the semiconductor device (100) is operating at a maximum voltage rating, an electrical field profile in the drift layer (104) extends less than 80% of the thickness of the drift layer (104), providing the radiation hardened nature of the device.