Schottky Diode Polysilicon Guard Ring Leakage Reduction
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Solution Overview
Problem
Schottky diodes face challenges with high reverse bias leakage and low breakdown voltage due to semiconductor doping and edge defects, which affect their integration and performance in semiconductor circuits.
Innovation Solution
A Schottky diode design incorporating a polysilicon guard ring with dual thickness dielectric regions and a threshold adjustment implant under the thinner dielectric portion, which reduces parasitic leakage and capacitance while enhancing breakdown voltage and forward conduction current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a Schottky diode is made with lightly doped semiconductor to reduce reverse bias parasitic capacitance, then capacitance is reduced, but series resistance increases and maximum current flow is restricted
Solution Approach 1:
The patent segments the semiconductor structure by introducing a separate heavily doped semiconductor region distinct from the lightly doped active region. This segmentation allows the lightly doped region to maintain low capacitance while the heavily doped region provides low resistance current paths, resolving the contradiction between capacitance reduction and resistance management.
Solution Approach 2:
The heavily doped semiconductor region acts as an intermediary between the metal contact and the lightly doped active region. It mediates the electrical connection by providing low series resistance while allowing the lightly doped region to maintain its low capacitance特性, thus resolving the contradiction between these two opposing requirements.
2Force
If the semiconductor material is very lightly doped to achieve low capacitance, then capacitance is reduced, but self-heating occurs due to semiconductor resistance causing thermal instability
Solution Approach 1:
The patent segments the semiconductor into lightly doped and heavily doped regions. The heavily doped regions serve as thermal management zones with lower resistance, reducing self-heating effects while the lightly doped active region maintains low capacitance, thus resolving the contradiction between capacitance and thermal stability.
3Speed
If Schottky diodes are made with metal contacts to semiconductor for fast response, then speed is improved, but reverse breakdown voltage is lower compared to junction diodes
Solution Approach 1:
The patent segments the semiconductor structure into regions with different doping levels, creating a heavily doped region that enhances breakdown voltage while maintaining the lightly doped active region for fast response. This segmentation allows the Schottky diode to achieve both high speed and high breakdown voltage 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 design effectively minimizes parasitic leakage and capacitance, increases reverse breakdown voltage, and improves forward conduction current, making it suitable for integration in CMOS processes without requiring additional diffused guard rings.
Implementation Method 1
a field insulator located at least partly in the semiconductor region, a dielectric region located over the semiconductor region between the field insulator and said one of the first and second terminals for isolating said material from the semiconductor region
Implementation Method 2
in Schottky diodes the conduction is dominated by majority carriers and occurs mostly by thermionic emission with some carrier diffusion
Implementation Method 3
in Schottky diodes the conduction is dominated by majority carriers and occurs mostly by thermionic emission with some carrier diffusion
Implementation Method 4
A Schottky diode design incorporating a polysilicon guard ring with dual thickness dielectric regions and a threshold adjustment implant under the thinner dielectric portion, which reduces parasitic leakage and capacitance while enhancing breakdown voltage
Data Source
AI summary
A Schottky diode including a semiconductor region, a first terminal comprising a metal or a metal silicide or being metallic, and a second terminal comprising at least a portion of the semiconductor region. The diode further includes an at least partly conductive material or a material capable of holding a charge in close proximity to, or in contact with, or surrounding one of the first and second terminals, a field insulator located at least partly in the semiconductor region, a dielectric region located over the semiconductor region between the field insulator and the one of the first and second terminals for isolating the conductive or charge-holding material from the semiconductor region, and wherein the dielectric region comprises insulating regions of different thicknesses.