Polycrystalline Silicon Anode for High-Voltage Diodes
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Solution Overview
Problem
High voltage semiconductor diodes face challenges in achieving a balance between dynamic properties and robustness against cosmic radiation, as highly doped anode regions can lead to breakdowns due to increased switching losses and reverse current peaks, while measures to reduce these often result in undesirable side effects such as reduced charge carrier lifetime.
Innovation Solution
A semiconductor diode design incorporating a monocrystalline silicon body with a polycrystalline silicon semiconductor region of higher doping concentration, which forms a pn-junction and is in electric contact with metallization, along with an edge-termination structure, to maintain low switching losses and reverse current peaks while enhancing robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If highly doped anode region is used, then robustness against cosmic radiation is improved, but switching losses and reverse current peaks increase
Solution Approach 1:
The anode region is segmented into two distinct parts: a monocrystalline anode region with lower doping concentration (first doping concentration) and a polycrystalline anode region with higher doping concentration (second doping concentration). This segmentation allows each region to fulfill different functions - the monocrystalline region maintains low switching losses while the polycrystalline region provides robustness against cosmic radiation and prevents breakdown.
Solution Approach 2:
Different doping concentrations and material structures are applied to different locations within the anode region. The monocrystalline region near the pn-junction has lower doping to reduce switching losses, while the polycrystalline region has higher doping to enhance robustness against cosmic radiation and prevent breakdown at the metallization interface.
2Reliability
If highly doped anode region is used, then breakdown is prevented, but reverse current peaks increase
Solution Approach 1:
The anode region is divided into monocrystalline and polycrystalline segments with different doping concentrations. The polycrystalline segment with higher doping concentration specifically addresses breakdown prevention and reverse current suppression, while the monocrystalline segment maintains low switching losses.
Solution Approach 2:
The anode region uses a composite structure combining monocrystalline silicon and polycrystalline silicon materials. This composite structure leverages the advantages of both materials - the monocrystalline material provides low loss characteristics while the polycrystalline material provides high doping concentration benefits for breakdown prevention and reverse current control.
3Loss of energy
If charge carrier life time is reduced by irradiation or ion implantation, then switching losses are reduced, but reverse current increases
Solution Approach 1:
Instead of changing charge carrier life time through irradiation or ion implantation, the invention changes the doping concentration parameter by introducing a polycrystalline region with higher doping concentration. This alternative parameter change achieves switching loss reduction without the harmful side effect of increased reverse current.
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 design effectively reduces switching losses and reverse current peaks while maintaining high robustness against cosmic radiation, preventing breakdowns and ensuring reliable operation under high voltage conditions.
Implementation Method 1
a polycrystalline silicon semiconductor region of the first conductivity type having a second maximum doping concentration which is higher than the first maximum doping concentration
Implementation Method 2
a second semiconductor region of a second conductivity type forming a pn-junction with the first semiconductor region
Data Source
AI summary
A semiconductor diode is provided. The semiconductor diode includes a monocrystalline silicon semiconductor body including a first semiconductor region of a first conductivity type extending to a first surface of the semiconductor body and having a first maximum doping concentration, and a second semiconductor region of a second conductivity type forming a pn-junction with the first semiconductor region. The semiconductor diode further includes a polycrystalline silicon semiconductor region of the first conductivity type having a second maximum doping concentration which is higher than the first maximum doping concentration and adjoining the first semiconductor region on the first surface, a first metallization arranged on the polycrystalline silicon semiconductor region and in electric contact with the polycrystalline semiconductor region, and an edge-termination structure arranged next to the first semiconductor region. Further, a method for producing a semiconductor diode is provided.