Low Voltage Antifuse Programming via SCR Latch Circuit
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Solution Overview
Problem
Existing methods for programming antifuses in integrated circuits face challenges with high resistance unpredictability, require large MOS transistors for high soaking currents, and are not well-suited for low voltage power supply and parallel programming.
Innovation Solution
A circuit that incorporates a semiconductor controlled rectifier (SCR) with a latch circuit including p-channel and n-channel transistors, allowing for programming of fuses at low voltage with reduced layout area and power dissipation, and enabling parallel programming of multiple fuses without affecting previously programmed ones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high soaking current (10-30 mA) is used to program the antifuse, then the dielectric rupture is achieved, but large MOS transistors are required increasing device complexity
Solution Approach 1:
The patent changes the electrical parameters by using an SCR-based latch circuit that maintains a holding current of less than 10 mA, significantly reducing the current requirement compared to conventional 10-30 mA soaking currents. This parameter change allows for smaller transistor sizes while maintaining reliable antifuse programming.
Solution Approach 2:
The SCR latch circuit acts as an intermediary between the programming voltage source and the antifuse. It provides the necessary current control and soaking function while requiring much smaller current than direct antifuse programming, thereby reducing the size of required MOS transistors.
2Reliability
If conventional fuse programming circuit is used, then fuse programming is achieved, but holding voltage is relatively high and separate fuse latch is required increasing device complexity
Solution Approach 1:
The patent merges the SCR latch circuit with the fuse latch circuit, eliminating the need for a separate fuse latch. The SCR is integrated into the existing latch structure, reducing overall device complexity while maintaining both fuse programming and latch functionality.
Solution Approach 2:
The SCR latch circuit serves multiple functions: it provides the holding voltage for fuse programming, acts as the latch mechanism, and enables low-voltage operation. This multi-functionality eliminates the need for separate dedicated components.
3Reliability
If high voltage is used for dielectric rupture, then antifuse programming is achieved, but power dissipation and heat generation increase
Solution Approach 1:
The patent uses a time-based approach where the programming voltage is applied in a controlled manner through the SCR latch. The holding region operation provides sustained low-current flow that achieves dielectric rupture and soaking without continuous high-power dissipation, reducing overall energy loss.
4Reliability
If conventional programming method is used, then fuse programming is achieved, but layout area is large
Solution Approach 1:
By integrating the SCR latch circuit with the fuse latch, the patent reduces the total layout area. The merged circuit shares common components and transistors, eliminating redundant structures and minimizing the overall footprint of the programming circuit.
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 solution achieves stable antifuse programming with reduced power dissipation and heat generation, allowing for reliable programming of fuses at low voltage with minimal layout requirements and efficient operation of multiple fuses in parallel.
Implementation Method 1
The antifuse is typically programmed by placing a voltage across the intervening dielectric to produce an electric field in excess of 10 MV/cm. This is sufficient to rupture the dielectric
Implementation Method 2
After dielectric rupture, therefore, the antifuse is subjected to a relatively high current of 10-30 mA for a short period of time and often at a lower voltage than required for dielectric rupture. This is often referred to as soaking the antifuse to melt and alloy the conductive material that penetrates the ruptured dielectric
Data Source
AI summary
A circuit for programming a fuse is disclosed. The circuit includes a voltage supply terminal (Vp) and a latch circuit comprising a p-channel transistor and an n-channel transistor (208-214). A semiconductor controlled rectifier (206) in the circuit includes at least one terminal of the p-channel transistor. A fuse (200) is coupled between the voltage supply terminal and the semiconductor controlled rectifier. The fuse is programmed in response to the semiconductor controlled rectifier.