Diode Base Peripheral Region for Recovery Breakdown Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor diodes with long carrier lifetimes in the n− semiconductor layer experience increased recovery current and potential recovery breakdown during switching from on-state to off-state, leading to device destruction, and existing solutions like electron beam irradiation or altering anode electrode placement either complicate the process or increase forward voltage drop.
Innovation Solution
A semiconductor device design featuring a semiconductor substrate with a base region, guard ring region, and deeper, lower-impurity base peripheral region to control hole injection and spread, preventing recovery breakdown without increasing forward voltage drop or altering carrier lifetimes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the lifetime of carriers in the n- semiconductor layer is increased to decrease forward voltage, then the forward voltage drop is reduced, but recovery current increases causing recovery breakdown
Solution Approach 1:
The patent applies local quality by creating a base peripheral region with different impurity concentration characteristics compared to the central base region. Specifically, the base peripheral region has a lower concentration of first conductivity type impurities, which locally modifies the carrier lifetime and hole injection characteristics at the periphery where breakdown occurs, while maintaining the overall low forward voltage drop of the diode.
2Reliability
If electron beam irradiation is applied to control carrier lifetime in the peripheral part, then recovery breakdown is prevented, but the manufacturing process becomes complicated
Solution Approach 1:
The patent employs preliminary action by forming the base peripheral region with modified impurity concentration during the initial semiconductor fabrication process, before the device is completed and before any carrier lifetime control would be needed. This is achieved through selective ion implantation or diffusion processes that create the lower impurity concentration region in advance, eliminating the need for subsequent electron beam irradiation or other post-processing lifetime control methods.
3Reliability
If the anode electrode edge is separated inward from the p semiconductor layer edge, then minority carrier concentration at the edge is reduced preventing breakdown, but the anode electrode area decreases increasing forward voltage drop
Solution Approach 1:
The patent resolves this contradiction by applying local quality through the base peripheral region with reduced first conductivity type impurity concentration. This allows the anode electrode to extend to the full edge of the p semiconductor layer (maintaining large area and low forward voltage drop) while the peripheral region's modified properties prevent excessive minority carrier concentration and breakdown at the edges.
4Reliability
If the base peripheral region is formed with lower impurity concentration, then hole injection is controlled preventing breakdown, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by modifying the impurity concentration parameter in the base peripheral region. By creating a region with lower first conductivity type impurity concentration compared to the central base region, the carrier lifetime and hole injection characteristics are changed locally. This can be achieved through controlled ion implantation or diffusion processes that adjust the impurity concentration parameter to prevent breakdown while maintaining manufacturability.
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 design effectively prevents recovery breakdown while maintaining a low forward voltage drop by controlling hole injection and spread, as verified through simulation, and allows for a simpler manufacturing process compared to previous methods.
Implementation Method 1
the concentration of the second conductivity type impurity included in the base peripheral region is lower than that included in the base region
Data Source
AI summary
A semiconductor device, including: a semiconductor substrate of the first conductivity type having a first surface and a second surface; a base region of the second conductivity type formed on the first surface of the semiconductor substrate; a guard ring region of the second conductivity type formed around the base region, and having the second type impurity of which concentration is lower than that of the base region; a first electrode formed on the base region; and a second electrode formed on the second surface of the semiconductor substrate, further including a base peripheral region formed around the base region and being connected to the base region, wherein the base peripheral region is deeper than the base region and has the substantially constant depth, and the concentration of the second conductivity type impurity included in the base peripheral region is lower than that included in the base region.