Semiconductor Device Schottky Zener Junction Trade-off
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Solution Overview
Problem
General Zener diodes have a long reverse recovery time, leading to delays in signal processing, especially at increased signal speeds, and using Schottky barrier diodes can reduce ESD tolerance.
Innovation Solution
A semiconductor device with a Schottky junction portion and a pn junction portion, where the pn junction portion has a higher withstand voltage than the Zener voltage, allowing for a shorter reverse recovery time and maintaining a high ESD tolerance by utilizing two independent regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a general Zener structure (pn junction portion) is used, then Zener characteristics are achieved, but reverse recovery time becomes long
Solution Approach 1:
The invention divides the semiconductor device into two distinct functional regions: a first conductivity type region (n-type) that forms a Schottky junction with the electrode for fast reverse recovery, and a second conductivity type region (p-type) that forms a pn junction for Zener breakdown characteristics. This segmentation allows each region to independently perform its specialized function without interfering with the other.
Solution Approach 2:
The invention merges a Schottky barrier diode structure and a Zener diode structure into a single integrated device. The Schottky junction portion handles the reverse recovery time requirement while the pn junction portion handles the Zener voltage clamping, combining the advantages of both diode types into one device that satisfies multiple performance requirements simultaneously.
2Loss of time
If a Schottky barrier diode is used to shorten reverse recovery time, then reverse recovery time is reduced, but ESD permissible amount is lowered
Solution Approach 1:
The device segments the current handling functions between two regions: the n-type first conductivity type region handles high-speed switching with the Schottky junction, while the p-type second conductivity type region provides enhanced ESD tolerance through the pn junction structure. This segmentation allows the ESD permissible amount to be maintained or improved while achieving fast reverse recovery.
Solution Approach 2:
The invention creates a composite semiconductor structure combining n-type and p-type regions with different properties. The n-type region optimized for Schottky junction performance provides fast reverse recovery, while the p-type region optimized for pn junction characteristics provides high ESD tolerance, creating a composite device that exhibits both properties simultaneously.
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 device achieves a balance between shortening reverse recovery time, maintaining Zener characteristics, and ensuring a high ESD tolerance, effectively addressing the limitations of both Schottky and Zener diodes.
Implementation Method 1
a Schottky electrode that is formed on the semiconductor layer and that forms a Schottky junction portion between a first conductivity type part of the semiconductor layer and the Schottky electrode
Implementation Method 2
a pn junction portion between the peripheral impurity region and the first conductivity type part of the semiconductor layer has a higher withstand voltage than a Zener voltage Vz of a Zener diode made of a pn junction portion between the second conductivity type region and the first conductivity type part of the semiconductor layer
Data Source
AI summary
A semiconductor device includes a first conductivity type semiconductor layer, a second conductivity type region selectively formed in the semiconductor layer, a second conductivity type peripheral impurity region formed around the second conductivity type region in the semiconductor layer, and a Schottky electrode that is formed on the semiconductor layer and that forms a Schottky junction portion between a first conductivity type part of the semiconductor layer and the Schottky electrode, and, in the semiconductor device, a pn junction portion between the peripheral impurity region and the first conductivity type part of the semiconductor layer has a higher withstand voltage than a Zener voltage VZ of a Zener diode made of a pn junction portion between the second conductivity type region and the first conductivity type part of the semiconductor layer.