Fuse Circuit ESD Protection via Bulk-Source Resistance
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Solution Overview
Problem
Conventional fuse circuits for final test trimming (FT-Trim) of IC chips lack sufficient electrostatic discharge (ESD) protection, leading to potential errors during ESD tests due to incorrect trimming.
Innovation Solution
A fuse circuit design that includes at least one electrical fuse and a control switch connected in series between a grounding pin and a predetermined pin, with a resistant device coupled between the bulk and source terminals to block current flow through the bulk terminal, enhancing ESD protection by preventing the electrical fuse from breaking during ESD events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the fuse circuit is connected in parallel with the ESD protection device, then the ESD protection is provided for the circuitry, but the electrical fuse may be broken during ESD test from the grounding pin due to current flow through parasitic diodes
Solution Approach 1:
A resistant device is introduced as an intermediary component between the bulk terminal and source terminal of the control switch. This resistor acts as a mediator that blocks the harmful current path through the parasitic diode during ESD events from the grounding pin, preventing the electrical fuse from breaking while maintaining ESD protection capability.
Solution Approach 2:
The resistance value of the resistant device is specifically designed to be higher than a predetermined threshold. By changing the resistance parameter, the circuit selectively blocks high-voltage ESD current paths while allowing normal operating currents to pass through, thus protecting the fuse during ESD tests without affecting normal functionality.
2Device complexity
If the control switch is designed without additional protective components, then the device complexity is reduced, but the fuse circuit lacks sufficient ESD protection during grounding pin stress
Solution Approach 1:
The resistant device serves as a protective intermediary that is minimally intrusive to the overall circuit structure. It is integrated into the existing control switch architecture by connecting between the bulk and source terminals, adding ESD protection functionality without significantly increasing device complexity or requiring major structural changes.
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 enhanced ESD protection prevents incorrect trimming of IC chips by ensuring the electrical fuse is not broken during ESD discharging, maintaining parameter precision and accuracy.
Implementation Method 1
a resistant device, coupled between the bulk terminal and the source terminal
Implementation Method 2
a bulk terminal, forming a parasitic diode with the drain terminal to block the predetermined current from flowing through the bulk terminal
Data Source
AI summary
The present invention discloses a fuse circuit for final test trimming of an integrated circuit (IC) chip. The fuse circuit includes at least one electrical fuse, at least one control switch corresponding to the electrical fuse, and a resistant device. The electrical fuse is connected with the control switch in series between a predetermined pin and a grounding pin. The control switch receives a control signal to determine whether a predetermined current flows through the corresponding electrical fuse and breaks the electrical fuse. The resistant device is coupled between a bulk terminal and a source terminal to increase a resistance of a parasitic channel, such that an electrostatic discharge (ESD) protection is enhanced, and errors of final test trimming of an IC chip are avoided.