String Contact Structure for High Voltage ESD Protection
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Solution Overview
Problem
Conventional contact arrays for electrostatic discharge (ESD) protection in semiconductor devices suffer from localized contact failure due to non-uniform ESD current distribution, leading to degraded ESD performance and potential device damage.
Innovation Solution
A string contact structure is introduced, where a continuous contact is formed along the terminals of a clamp device, coupled with conductive layers to the pad and ground, allowing for uniform current distribution and enhanced ESD protection without major process changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional contact array is used for ESD protection, then the device can provide ESD protection, but localized contact damage occurs due to non-uniform ESD current distribution
Solution Approach 1:
The contact array is divided into multiple individual contact holes arranged in a specific pattern. This segmentation allows the ESD current to be distributed across multiple discrete contact points rather than concentrating in a single location, preventing localized contact damage while maintaining overall ESD protection capability.
Solution Approach 2:
Different regions of the contact array are designed with varying contact hole densities and configurations. By optimizing the local distribution of contact holes in different areas, the current density is evenly distributed across all contacts, preventing any single contact from experiencing excessive current that would cause localized damage.
2Reliability
If a contact array with multiple contact holes is used, then ESD protection is provided, but non-uniform ESD current flow degrades ESD performance
Solution Approach 1:
The contact array employs an asymmetric arrangement of contact holes with varying sizes, shapes, and spacing patterns rather than a uniform grid. This asymmetric design compensates for non-uniform current flow tendencies by strategically placing larger or more numerous contacts in regions where current density is naturally higher, achieving overall uniform current distribution.
Solution Approach 2:
The contact array is designed to create equipotential regions across the contact structure by carefully controlling the spacing, size, and distribution of contact holes. This ensures that voltage potential is evenly distributed across all contact points, promoting uniform current flow through each contact and preventing concentration in specific areas.
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 string contact structure significantly improves ESD performance by withstanding higher ESD currents and preventing localized contact failures, ensuring more reliable ESD protection for semiconductor devices.
Implementation Method 1
forming one or more conductive layers on the string contact to couple the first terminal and the second terminal of the clamp device to the pad and a ground pad
Data Source
AI summary
The present invention relates to an electrostatic discharge (ESD) protection scheme and particularly to a string contact structure for an improved ESD performance. In an embodiment, the invention provides a method for forming an ESD protection circuit for protecting an internal circuit from damage due to an ESD voltage appearing on a pad coupled to a clamp device including a first terminal and a second terminal. The method includes forming a string contact along the first terminal and the second terminal of the clamp device. The method further includes forming one or more conductive layers on the string contact to couple the first terminal and the second terminal of the clamp device to the pad and a ground pad.