Lateral PN Junction Diode With Field Plate for FDSOI Breakdown Control
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Solution Overview
Problem
In advanced fully-depleted silicon-on-insulator (FDSOI) technologies, pn junction diodes constructed on conventional bulk substrates face limitations in achieving high breakdown voltage due to the location of the pn junction deep within the substrate, which affects the reverse-bias junction breakdown voltage and leakage current.
Innovation Solution
A semiconductor device with a pn junction located beneath a buried oxide layer and extending orthogonally to the substrate surface, combined with a field plate electrode above the buried oxide layer to modify the electric field, allowing for increased breakdown voltage and tunable leakage current through bias voltage application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pn junction is located deep in the substrate (conventional vertical device), then the breakdown voltage is determined by junction doping, but the leakage current cannot be effectively controlled and the breakdown voltage cannot be increased substantially
Solution Approach 1:
The patent transitions from a conventional vertical pn junction (deep in substrate) to a lateral pn junction configuration where the junction extends orthogonally beneath the buried oxide layer. This dimensional repositioning allows the junction to be closer to the surface while maintaining high breakdown voltage, and enables field plate control of the electric field to reduce leakage current.
Solution Approach 2:
The field plate electrode acts as an intermediary element positioned above the buried oxide layer. By applying a bias voltage to the field plate, the electric field at the pn junction can be modified, providing control over both breakdown voltage and leakage current without directly altering the junction structure.
2Device complexity
If the pn junction is located at the interface between the underside of a p-type region and the n-well (vertical device), then the structure is simple, but the breakdown voltage cannot be increased substantially compared to conventional devices
Solution Approach 1:
The patent repositions the pn junction from a vertical configuration (at the interface between p-type region and n-well) to a lateral configuration extending orthogonally beneath the buried oxide layer. This dimensional change increases the effective breakdown voltage while maintaining reasonable structural complexity through the use of standard SOI layers.
Solution Approach 2:
The patent creates a localized high-doped region (n-type region with doping concentration of 1e19 to 1e21 atoms/cm³) immediately beneath the buried oxide layer to form the pn junction. This localized doping enhancement increases the breakdown voltage at the critical junction region without requiring changes to the entire device structure.
3Adaptability or versatility
If the pn junction is located deeper into the substrate, then the breakdown voltage is determined by junction doping, but the control over breakdown voltage and leakage current is limited
Solution Approach 1:
The field plate electrode serves as a control intermediary positioned above the buried oxide layer. By adjusting the bias voltage on the field plate, the electric field distribution at the pn junction can be tuned, providing adaptability in controlling both breakdown voltage and leakage current without changing the physical distance to the junction.
Solution Approach 2:
The patent introduces a dynamically controllable field plate electrode that can adjust the electric field at the pn junction through variable bias voltage. This dynamic control mechanism allows the breakdown voltage and leakage current to be tuned according to different operating conditions, enhancing device adaptability.
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 configuration enhances the breakdown voltage and allows for better control of leakage current, improving the performance of the pn junction diode by positioning the pn junction closer to the field plate electrode for closer control of breakdown voltage and leakage current.
Implementation Method 1
a field plate electrode comprising a semiconductor region located above the buried oxide layer for modifying an electric field at the pn junction by application of a potential to the field plate electrode
Implementation Method 2
The reverse-bias junction breakdown voltage is one of the key Figure of Merit (FoM) for these devices
Data Source
AI summary
A semiconductor device comprising a pn junction diode and a method of making the same. The device includes a semiconductor substrate having a first conductivity type. The device also includes a buried oxide layer located in the substrate. The device further includes a semiconductor region having a second conductivity type extending beneath the buried oxide layer to form a pn junction with a semiconductor region having the first conductivity type. The pn junction is located beneath the buried oxide layer and extends substantially orthogonally with respect to a major surface of the substrate. The device also includes a field plate electrode comprising a semiconductor region located above the buried oxide layer for modifying an electric field at the pn junction by application of a potential to the field plate electrode.