Semiconductor Recombination Zone via Rear-Surface Impurity Implantation
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Solution Overview
Problem
Existing methods for reducing carrier lifetime in semiconductor components, such as high-energy particle irradiation and heavy metal diffusion, often adversely affect the front side, including gate oxides, leading to undesirable shifts in threshold voltage and electrical instability.
Innovation Solution
Introducing impurities with low diffusion constants, such as tungsten or tantalum, as recombination centers during semiconductor body production, ensuring they form a recombination zone at a distance from the surfaces to avoid surface contamination and influence, using masked implantation and epitaxial growth to control the recombination zone's extent and location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If high-energy particle irradiation or heavy metal diffusion is used to reduce carrier lifetime, then carrier lifetime is reduced and reverse current is lowered, but the front side including gate oxide is adversely affected causing threshold voltage shift and electrical instability
Solution Approach 1:
The patent applies local quality by creating a recombination zone with specific impurity concentration in the drift zone while keeping the front surface and gate oxide regions free from contamination. The impurities are introduced at controlled depths (e.g., 1-10 micrometers from the rear surface) to achieve local carrier lifetime reduction without affecting the front surface electrical properties.
Solution Approach 2:
The patent inverts the conventional approach by introducing impurities from the rear surface instead of the front surface. This reverse direction method allows the recombination zone to be formed in the drift zone while protecting the gate oxide and front surface structures from contamination and damage.
2Duration of action of moving object
If impurities are introduced into the semiconductor body, then recombination centers are formed and carrier lifetime is reduced, but surface state density may be affected and manufacturing equipment may be contaminated
Solution Approach 1:
The patent inverts the conventional approach by introducing impurities from the rear surface instead of the front surface. This reverse direction method allows the recombination zone to be formed in the drift zone while protecting the gate oxide and front surface structures from contamination and damage.
Solution Approach 2:
The patent uses an intermediary approach by introducing impurities through the rear surface which acts as a mediator to deliver recombination centers to the drift zone without directly contaminating the front surface. The impurities are transported through the bulk material to the target region, preventing direct contact with sensitive front surface structures.
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 effectively reduces carrier lifetime without affecting the surface state density or electrical properties, maintaining stability and performance in semiconductor components like IGBTs and diodes, while preventing contamination of manufacturing equipment.
Implementation Method 1
introducing impurities with low diffusion constants, such as tungsten or tantalum, as recombination centers during semiconductor body production
Implementation Method 2
using masked implantation and epitaxial growth to control the recombination zone's extent and location
Implementation Method 3
introducing impurities which act as recombination centers in the semiconductor body and form a recombination zone
Data Source
AI summary
In a method for producing a semiconductor body, impurities which act as recombination centers in the semiconductor body and form a recombination zone are introduced into the semiconductor body during the process of producing the semiconductor body. In a semiconductor component, comprising a semiconductor body having a front surface and an opposite rear surface, and also a recombination zone formed by impurities between the front and rear surfaces, wherein the impurities act as recombination centers, the surface state density at the front and rear surfaces of the semiconductor body is just as high as the surface state density at a front and rear surface of an identical semiconductor body without a recombination zone.