Field-Assisted Dopant Diffusion for GaN Superjunction Devices
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Solution Overview
Problem
Current methods for creating superjunction devices, particularly in GaN, face challenges in achieving high breakdown voltage with low switching resistance due to limitations in doping precision and the introduction of impurities and defects during the doping process, especially with high-temperature annealing and ion implantation techniques.
Innovation Solution
The use of field-assisted diffusion methodology to dope semiconductor layers, allowing for lower temperature and shorter time processes, which enables precise control of doping profiles and reduces lattice damage, using a source layer and cap layer to facilitate diffusion and maintain the integrity of the GaN substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-temperature annealing and ion implantation techniques are used to dope semiconductor layers, then doping precision can be improved, but impurities and defects are introduced into the semiconductor crystal
Solution Approach 1:
The patent changes the temperature parameter from high-temperature annealing to low-temperature field-assisted diffusion, and changes the doping method from ion implantation to field-driven dopant diffusion, thereby achieving precise doping without introducing impurities and defects
Solution Approach 2:
The patent replaces the mechanical ion implantation process with a field-assisted diffusion process where dopants are driven by electric fields through the semiconductor lattice, avoiding the physical damage and defects caused by ion bombardment
2Reliability
If traditional high-temperature processes are used for doping, then dopant activation can be achieved, but lattice damage occurs and processing time increases
Solution Approach 1:
The patent changes the temperature parameter from high-temperature processing to low-temperature field-assisted diffusion, enabling dopant activation without causing lattice damage or requiring extended processing times
3Manufacturing precision
If multiple masked ion implantation and regrowth steps are used to create charge balancing layers, then doping patterns can be controlled, but the process complexity and impurity introduction increase
Solution Approach 1:
The patent extracts and eliminates the need for multiple masking and regrowth steps by using field-assisted diffusion that naturally creates the desired doping patterns through electric field distribution, simplifying the overall fabrication process
Solution Approach 2:
The patent introduces electric fields as an intermediary mechanism to control dopant distribution, replacing the complex sequence of masking and implantation steps with a single field-driven diffusion process
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 enables the creation of superjunction devices with improved breakdown voltage and reduced conduction loss, allowing for higher voltage handling with lower power loss, while avoiding the limitations of traditional high-temperature processes and lattice damage.
Implementation Method 1
field assisted diffusion of dopants
Implementation Method 2
distributing an electric field within the voltage sustaining layer
Implementation Method 3
The dopant is more concentrated along a sidewall of the voltage sustaining layer than toward a center of the voltage sustaining layer
Data Source
AI summary
An apparatus, in accordance with one embodiment, includes a superjunction device having a voltage sustaining layer formed of a semiconductor material and a dopant in the voltage sustaining layer. The dopant is for distributing an electric field within the voltage sustaining layer. The dopant is more concentrated along a sidewall of the voltage sustaining layer than toward a center of the voltage sustaining layer, the sidewall extending at least a portion of the distance between a top surface and a bottom surface of a voltage sustaining layer. Methods of electric field-enhanced dopant diffusion to form a superjunction device are also presented.