Vertical SCR ESD Structure for Holding Voltage and Current
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Solution Overview
Problem
Conventional electrostatic discharge (ESD) devices face a challenge in achieving both high current performance and high holding voltage, typically requiring a tradeoff between the two, which can lead to device failure in high-voltage applications.
Innovation Solution
The integration of a vertical silicon controlled rectifier (SCR) and a vertical NPN device, with specific dopant layers and structures, enables high current performance while maintaining high holding voltage, and is fabricated using integrated circuit technology with photolithographic processes, saving chip area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high voltage PNP device is used, then holding voltage control is improved, but current performance deteriorates
Solution Approach 1:
The patent combines a PNP device and an NPN device into a single integrated ESD protection device. The PNP portion provides high holding voltage control while the NPN portion contributes high current performance, allowing both functions to coexist in one device structure rather than requiring separate devices.
Solution Approach 2:
The device uses a composite structure with different doped regions (P-type and N-type semiconductors) arranged in a specific configuration. This composite semiconductor structure enables the device to exhibit both high holding voltage characteristics from the PNP portion and high current performance from the NPN portion simultaneously.
2Productivity
If a low voltage/high voltage silicon controlled rectifier (SCR) is used, then current performance is improved, but holding voltage control deteriorates
Solution Approach 1:
The patent merges SCR functionality with bipolar transistor characteristics in a unified device structure. The SCR portion handles high current performance while the bipolar PNP-NPN configuration provides precise holding voltage control, resolving the tradeoff between these two parameters.
Solution Approach 2:
Different regions of the device have specialized functions: the SCR portion is optimized for current handling while the PNP-NPN bipolar regions are optimized for voltage control. This local specialization allows each part of the device to excel at its specific function while contributing to overall device performance.
3Ease of manufacture
If conventional ESD device structures are used, then manufacturing simplicity is maintained, but device reliability in high-voltage applications deteriorates
Solution Approach 1:
The device is segmented into distinct functional regions (P-type regions, N-type regions, buried layers) that can be formed using standard semiconductor fabrication processes. This segmentation allows complex functionality to be achieved through modular construction using established manufacturing techniques.
Solution Approach 2:
The device structure is designed to perform multiple functions within a single integrated architecture: ESD protection, high current handling, precise holding voltage control, and lateral SCR prevention. This multi-functionality is achieved using standard semiconductor fabrication processes, making the complex device manufacturable with existing technology.
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to high-voltage electrostatic discharge (ESD) devices and methods of manufacture. The structure comprising a vertical silicon controlled rectifier (SCR) connecting to an anode, and comprising a buried layer of a first dopant type in electrical contact with an underlying continuous layer of a second dopant type within a substrate.