Anti-Fuse OTP Bitcell Using Self-Heating Dielectric Rupture
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Solution Overview
Problem
Existing semiconductor manufacturing processes face challenges in implementing one-time programmable (OTP) bitcells due to limitations in dielectric thickness, spacing between devices, and the need for I/O devices, leading to increased circuit area and potential leakage issues.
Innovation Solution
The use of self-heating properties in anti-fuse FETs to locally heat the dielectric, reducing the required rupture voltage and allowing for a single-step or two-step programming process, which selectively heats and applies voltage to rupture the dielectric, thereby simplifying peripheral circuits and reducing area usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional OTP bitcell implementation is used, then reliable memory storage is achieved, but circuit area increases and leakage issues occur due to requirements for I/O devices and voltage splitting
Solution Approach 1:
The invention extracts and removes the I/O devices from the OTP bitcell structure, eliminating the need for separate input/output transistors. The bitcell is reconfigured to use only the essential anti-fuse FET and minimum peripheral circuitry, directly reducing circuit area while maintaining programming and reading functionality through modified voltage application sequences
Solution Approach 2:
The anti-fuse FET is designed to serve multiple functions: it acts as both the storage element and the programming switch. The same transistor structure is used for both data retention and programming operations, eliminating the need for dedicated I/O devices and reducing overall circuit complexity and area
2Manufacturing precision
If conventional voltage splitting is used for dielectric rupture, then precise control is achieved, but device spacing increases and circuit complexity rises
Solution Approach 1:
The invention changes the voltage parameter application method by using temporary voltage overrides on the gate terminal. Instead of permanent voltage splitting across multiple devices, high voltage is temporarily applied to the gate during programming operations, enabling precise rupture control without requiring increased device spacing or complex voltage splitting networks
Solution Approach 2:
The gate voltage is prepared and applied in advance of the actual rupture operation. The control circuit pre-charges the gate capacitor to the required voltage level before initiating the programming sequence, ensuring precise rupture voltage control is achieved without requiring complex real-time voltage division circuits
3Reliability
If anti-fuse FET is used for OTP storage, then non-volatile memory is achieved, but programming complexity increases due to thermal management requirements
Solution Approach 1:
The anti-fuse FET structure itself provides the thermal management function through its inherent physical properties. The device self-regulates the heating process during programming, eliminating the need for external thermal management circuits or complex control mechanisms. The programming circuitry simply applies voltage, and the device's physical structure handles the thermal aspects of dielectric rupture
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 enables the implementation of OTP bitcells in processes with single gate dielectric thickness, without I/O devices, and reduces circuit area by minimizing the need for voltage splitting, thus addressing leakage and spacing constraints.
Implementation Method 1
A current may be passed through a channel of an anti-fuse field-effect transistor (FET) to increase a temperature of a gate dielectric of the anti-fuse FET
Implementation Method 2
The gate dielectric may be ruptured by applying a first voltage between the gate dielectric and the channel of the anti-fuse FET
Data Source
AI summary
A current may be passed through a channel of an anti-fuse field-effect transistor (FET) to increase a temperature of a gate dielectric of the anti-fuse FET and change a rupture voltage of the gate dielectric of the anti-fuse FET from a first rupture voltage to a second rupture voltage. The gate dielectric may be ruptured by applying a first voltage between the gate dielectric and the channel of the anti-fuse FET, where the first voltage is between the first rupture voltage and the second rupture voltage.