SCR-LDMOS Composite Structure for High Voltage ESD Protection
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Solution Overview
Problem
Conventional SCR and LDMOS devices for high voltage IC electrostatic discharge (ESD) protection have low sustaining voltages, leading to latching up and malfunction, while diodes require large device areas for sufficient self-protection, failing to meet all necessary parameters.
Innovation Solution
An SCR-LDMOS structure with specific implanted regions and polysilicon gate, where the first N implanted region is formed with injection energy and doping concentration to adjust the sustaining voltage, reducing base resistance and increasing doping concentration, thereby enhancing the sustaining voltage and reducing trigger voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional SCR or LDMOS devices are used for high voltage IC ESD protection, then the device structure is simple, but the sustaining voltage is low causing latching up and malfunction
Solution Approach 1:
The patent combines SCR and LDMOS devices into a single integrated structure where the LDMOS drain region shares the same P-well and N-well regions as the SCR. This merging allows the composite device to achieve higher sustaining voltage through the LDMOS component while maintaining the ESD protection functionality of the SCR, resolving the contradiction between reliability and structural simplicity.
Solution Approach 2:
The invention creates a composite device structure integrating two different semiconductor device types (SCR and LDMOS) with complementary characteristics. The SCR provides low trigger voltage for ESD activation, while the LDMOS contributes high breakdown voltage for sustained operation, achieving both high reliability and appropriate structural complexity.
2Reliability
If diode is used for ESD protection, then self-protection ability is sufficient, but device area is large
Solution Approach 1:
The SCR-LDMOS composite device performs multiple functions within a single compact structure: it provides ESD protection through the SCR's latching mechanism, achieves sufficient self-protection capability through the LDMOS's high breakdown voltage, and maintains compact area by sharing common regions between the two device components, eliminating the need for separate protection devices.
3Reliability
If SCR structure is used, then trigger voltage is low for ESD protection, but sustaining voltage is low causing latching up
Solution Approach 1:
The invention segments the device functionality into two distinct components within a unified structure: the SCR portion handles trigger activation with low voltage for ESD detection, while the LDMOS portion provides high voltage sustainment to prevent latching up. This functional segmentation resolves the contradiction between low trigger voltage and high sustaining voltage requirements.
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 solution increases the sustaining voltage and reduces the trigger voltage, improving the SCR's ability to handle ESD without latching up, while maintaining a high impedance state for normal operation, thus enhancing the IC's self-protection capabilities.
Implementation Method 1
Electrostatic discharge (ESD) is a natural phenomenon in daily life. In ESD, in a short time, heavy currents will be generated, causing fatal damage to ICs
Implementation Method 2
a P+ implanted region in the N well, said P+ implanted region forming an anode of the SCR apparatus, and a first N+ implanted region in the P well
Data Source
Figure 1
Figure 2
AI summary
A silicon controlled rectifier (SCR) apparatus is provided. The SCR apparatus includes an SCR structure and a first injection region (8). The SCR structure includes a P+ injection (1), a P well (5), an N well (7) and a first N+ injection region (9), the first N injection region (8) is located under an anode terminal of the P+ injection region (1) of the SCR structure. A method for adjusting a sustaining voltage is provided as well.