Distributed SCR ESD Protection Layout for Smaller IC Footprint
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Solution Overview
Problem
Existing ESD protection devices for integrated circuits are large and occupy significant space, as they need to dissipate large amounts of charge quickly, which limits their integration and efficiency.
Innovation Solution
The proposed solution involves an integrated circuit design that includes a p-type substrate layer, an ESD protection device with a lower-doped n-well and higher-doped contact regions, and a trigger device connected to a further higher-doped p+ contact region. This configuration uses a silicon controlled rectifier (SCR) with n-wells remote from the ESD device to distribute the ESD current, reducing the size of the ESD protection device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ESD protection device is designed to dissipate large amounts of charge quickly, then the protection effectiveness is improved, but the device size increases significantly
Solution Approach 1:
The ESD protection function is segmented between the trigger device (localized near I/O pin) and remote n-well regions (distributed across the substrate). The trigger device initiates protection while remote n-wells dissipate charge, dividing the dissipation function across multiple spatial locations rather than concentrating it in one large device.
Solution Approach 2:
The invention transitions from a two-dimensional planar ESD protection structure to a three-dimensional distributed structure by utilizing vertical n-well regions spaced throughout the substrate depth and horizontal distance. This spatial distribution across multiple dimensions allows charge dissipation without increasing the footprint area.
2Productivity
If the ESD protection device size is reduced, then the IC integration efficiency is improved, but the charge dissipation capability may be compromised
Solution Approach 1:
Remote n-well regions serve dual functions: they act as normal operational wells during standard IC operation and as ESD dissipation paths during electrostatic discharge events. This multi-functionality allows the same structural elements to support both integration efficiency and protection capability without requiring dedicated ESD structures.
Solution Approach 2:
The remote n-well regions automatically activate as ESD dissipation paths when triggered by the trigger device, without requiring external control or additional active components. The distributed n-wells self-organize to handle charge dissipation based on their spatial distribution and electrical 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
This design effectively reduces the size of the ESD protection device while maintaining its functionality, allowing for more efficient and compact integration of ESD protection within integrated circuits.
Implementation Method 1
the further region lower-doped n-well is operable as a cathode of a silicon controlled rectifier, SCR, comprising the anode, the ESD protection device lower-doped n-well region as an n-intermediate node, and the p-doped substrate as a p-intermediate node
Data Source
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AI summary
Disclosed is a method and IC, comprising: a p-type substrate layer (410), an ESD protection device (420), and a further region (430); wherein the ESD protection device comprises: a n-well region (422) having therein a n+ contact region (424) and a p+ anode contact region (426), and a trigger device (428) connected between the n+ contact region and a further p+ contact region (446) outside of the n-well, wherein the trigger device is operable, in response to an ESD event trigger, to provide a low-resistance path between the anode contact region and the further p+ contact region; wherein the further region comprises a further n-well (432), spaced apart from the ESD protection device lower-doped n-well region (422); and wherein the further n-well is operable as a cathode of an SCR comprising the anode, and the ESD protection device n-well and the p-doped substrate layer as a n- and p-intermediate nodes.