Guard Ring ESD Protection with Contact-Free Weak Spot
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Solution Overview
Problem
The existing electrostatic protection circuits in semiconductor integrated circuits face challenges in reducing the risk of destruction at weak spots in the PN junctions between protection devices and guard ring regions, particularly due to high current density and impedance issues during surge discharge, which can lead to device destruction and increased chip area requirements.
Innovation Solution
The solution involves forming a semiconductor integrated circuit with a guard ring structure around the protection device, where the guard ring has a ring-like planar shape and lacks electrical contacts on the side facing the weak spot, thereby increasing series resistance and reducing the risk of destruction. This design maintains ESD endurance while minimizing device area by optimizing the distance between impurity regions and the guard ring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical contacts are formed in the guard ring facing the weak spot, then the ESD protection capability is improved, but the current density at the weak spot increases causing device destruction
Solution Approach 1:
The patent extracts removes the electrical contacts from the guard ring portion facing the weak spot (PN junction between protection device and guard ring). This extraction eliminates the direct current path through the guard ring at the vulnerable location, preventing high current density from concentrating at the weak spot during ESD events, while maintaining ESD protection capability through alternative current paths.
Solution Approach 2:
The patent applies different structural qualities to different portions of the guard ring. The guard ring has electrical contacts in most portions to provide ESD protection, but deliberately lacks contacts in the specific portion facing the weak spot. This local differentiation allows the structure to provide protection where needed while avoiding harm where vulnerable.
2Area of stationary object
If the guard ring is positioned closer to the protection device, then the device area is reduced, but the impedance decreases increasing the risk of destruction
Solution Approach 1:
The patent optimizes the positional parameter of the guard ring relative to the protection device. By carefully controlling the distance and arrangement between the guard ring and the protection device, the design achieves compact area while maintaining sufficient impedance to prevent destruction at weak spots during surge discharge events.
3Reliability
If the guard ring is positioned farther from the protection device, then the impedance increases reducing destruction risk, but the device area increases
Solution Approach 1:
The patent optimizes the positional parameter of the guard ring relative to the protection device. By carefully controlling the distance and arrangement between the guard ring and the protection device, the design achieves compact area while maintaining sufficient impedance to prevent destruction at weak spots during surge discharge events.
4Reliability
If multiple electrical contacts are formed in the guard ring, then the ESD current distribution is improved, but the current density at weak spots increases causing device destruction
Solution Approach 1:
The patent extracts removes the electrical contacts from the guard ring portion facing the weak spot (PN junction between protection device and guard ring). This extraction eliminates the direct current path through the guard ring at the vulnerable location, preventing high current density from concentrating at the weak spot during ESD events, while maintaining ESD protection capability through alternative current paths.
Solution Approach 2:
The patent applies different structural qualities to different portions of the guard ring. The guard ring has electrical contacts in most portions to provide ESD protection, but deliberately lacks contacts in the specific portion facing the weak spot. This local differentiation allows the structure to provide protection where needed while avoiding harm where vulnerable.
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 approach effectively reduces the risk of destruction at weak spots in the PN junctions, maintains ESD endurance, and minimizes the device area, addressing the challenges of high current density and impedance while ensuring reliable surge discharge handling.
Implementation Method 1
lacks electrical contacts on the side facing the weak spot, thereby increasing series resistance and reducing the risk of destruction
Data Source
AI summary
A semiconductor integrated circuit includes a first conduction-type semiconductor region, a second conduction-type first impurity region, and a guard ring formed using a first conduction-type second impurity region so as to form a protection device of an electrostatic protection circuit. The first impurity region is formed inside the semiconductor region to have a rectangular planar structure with long and short sides. The guard ring is formed inside the semiconductor region to surround the periphery of the first impurity region. A weak spot is formed on the short side of the rectangular planar structure of the first impurity region. A plurality of electrical contacts are formed in a first portion of the guard ring which faces the long side of the rectangle. A plurality of electrical contracts are not formed in a second portion of the guard ring which faces the weak spot formed on the short side of the rectangle.