Fast-Avalanche Diode Structure for Thick High-Voltage Active Regions
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Solution Overview
Problem
Existing high-voltage fast-avalanche diodes require thin active regions to achieve fast operation, which limits the device voltage and complicates manufacturing, necessitating deep diffusion and thin wafers that are prone to breaking.
Innovation Solution
A high-voltage fast-avalanche diode with a thick active region exceeding 300 microns is developed using a high-quality float-zone wafer, eliminating the need for deep diffusion and allowing easier handling, achieved through a p+-n0-n+ structure with boron and phosphorus spin-on-dopant junctions, supported by numerical simulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a thin active region is used to achieve fast operation, then the rise-time is reduced, but the device voltage is lowered
Solution Approach 1:
The patent changes the substrate quality parameter from standard to high-quality float-zone wafer with high-resistivity, enabling the active region to be thick (>300 microns) while maintaining fast operation. This parameter change in substrate quality compensates for the increased thickness, resolving the contradiction between thickness and speed.
2Speed
If a thin wafer is used to achieve fast operation, then the rise-time is reduced, but the manufacturing complexity increases due to deep diffusion requirements
Solution Approach 1:
Instead of using a thin wafer and performing deep diffusion to create a thin active region, the patent inverts the approach by using a thick high-quality wafer where the entire thickness becomes the active region. This eliminates the need for deep diffusion processes and reduces manufacturing complexity while maintaining fast operation.
3Speed
If a thin wafer is used to achieve fast operation, then the rise-time is reduced, but the reliability decreases due to breaking risk
Solution Approach 1:
The patent inverts the conventional approach by using a thick wafer instead of a thin wafer. This thick high-quality float-zone wafer is inherently more mechanically robust and less prone to breaking during handling and processing, thereby improving reliability while maintaining fast operation characteristics.
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 diode operates in the 100-ps range with higher voltage and simplified manufacturing, demonstrating a 7.9-kV rise-time and 52 kV/ns rise-rate without breakdown, outperforming prior art in voltage rise-rate and sharpening quality.
Implementation Method 1
when a 8 kV/0.8 ns ramp is applied to a 100 micron p+-n-n+ structure, it results in a super-fast turn on from 8 kV to 10V in 15 ps
Data Source
AI summary
A method of using a diode device including providing a diode that includes an active region including a 525 micron thick. 10 kΩ-cm, n-type, float zone wafer, and operating the diode as a silicon-avalanche semiconductor switch.