Bi-directional Breakdown SCR for Symmetric ESD Protection

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Solution Overview

Problem

Conventional silicon controlled rectifiers (SCRs) in 5G networks face challenges with external stress like electrostatic discharge (ESD) due to non-uniform trigger voltages and area constraints, as they require multiple single-direction SCRs in series with diodes, which do not provide symmetric protection for +/− voltage windows.

Innovation Solution

The implementation of bi-directional breakdown SCRs with directly connected p-type (P+) and n-type (N+) wells, using silicide blocks and shallow trench isolation, allows for uniform trigger voltage and symmetric protection of +/− voltage windows, reducing the area required for ESD protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple single direction SCRs in series with diodes are used for ESD protection, then ESD protection capability is improved, but area consumption increases

Engineering Contradiction:

ImproveESD protection capabilityVSAvoidarea consumption

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent combines multiple single-direction SCRs into a single bi-directional breakdown SCR structure. By integrating the functionality of multiple SCRs and diodes into one unified device with shared P+ and N+ wells, the area consumption is reduced while maintaining ESD protection capability for both positive and negative voltage windows.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The bi-directional breakdown SCR structure provides universal ESD protection for both positive and negative voltage windows simultaneously. The shared P+ and N+ wells enable the device to function as multiple SCRs would, but in a compact single structure that handles bidirectional voltage breakdown protection.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Ease of manufacture

If isolated P+ wells are used in conventional devices, then manufacturing simplicity is maintained, but trigger voltage uniformity deteriorates

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidtrigger voltage uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent connects the P+ wells together through a common P+ well structure, ensuring they are at the same electrical potential. This equipotential connection guarantees uniform trigger voltage across all SCR structures sharing the same P+ and N+ wells, eliminating the non-uniformity caused by isolated P+ wells at different potentials.

Inventive Principle:

Principle #12Equipotentiality

3Device complexity

If conventional single direction SCRs are used, then device simplicity is maintained, but symmetric protection for +/− voltage windows is lost

Engineering Contradiction:

Improvedevice simplicityVSAvoidsymmetric protection capability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent employs asymmetric well sharing where P+ wells are commonly shared to provide uniform trigger voltage, while N+ wells can be isolated by STI structures for area reduction. This asymmetric design enables symmetric bidirectional protection capability while maintaining manufacturing efficiency and area optimization.

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentUS11171132B2Bi-directional breakdown silicon controlled rectifiers

Publication Date: 2021.11.09 GLOBALFOUNDRIES US INC

AI summary

The present disclosure relates to semiconductor structures and, more particularly, to bi-directional silicon controlled rectifiers (SCRs) and methods of manufacture. The structure includes: a plurality of diffusion regions; a plurality of p-type (P+) wells adjacent to the diffusion regions, wherein the P+ wells are directly connected; and a plurality of n-type (N+) wells adjacent to the P+ wells.