OTP Memory Cell Schottky Diode Layout for Reliable Programming
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Solution Overview
Problem
Existing one-time programmable (OTP) memory cells face challenges in reliably programming and reading data due to inconsistent breakdown of insulating layers during programming operations, leading to potential data loss and performance issues.
Innovation Solution
Incorporating Schottky diodes between word lines and transistors in OTP memory cells, which allows for controlled programming and reading by blocking reverse leakage currents, ensuring reliable data storage and retrieval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a programming electric field is applied across the dielectric material layer to sustainably alter the dielectric material, then the resistance of the dielectric material layer decreases, but the breakdown process becomes inconsistent leading to potential data loss
Solution Approach 1:
A Schottky diode is introduced as an intermediary component between the word line and the bit line in the OTP memory cell. The Schottky diode provides a controlled rectifying junction that ensures unidirectional current flow during programming operations, preventing reverse leakage currents that cause inconsistent breakdown. This intermediary component stabilizes the programming process by controlling the electric field distribution across the dielectric layer, thereby improving both reliability and manufacturing precision.
Solution Approach 2:
The patent utilizes the unique electrical parameters of the Schottky diode, specifically its low forward voltage drop and high reverse breakdown voltage, to control the programming process. By changing the voltage parameters applied to the Schottky diode during programming, the electric field across the dielectric material is precisely controlled, ensuring consistent breakdown characteristics. This parameter control mechanism resolves the inconsistency in dielectric breakdown while maintaining high programming reliability.
2Reliability
If Schottky diodes are incorporated to block reverse leakage currents, then programming reliability improves, but device complexity increases
Solution Approach 1:
The Schottky diode is merged with the existing word line and bit line structures of the OTP memory cell, sharing common conductive paths and interconnect layers. Instead of adding completely separate components, the Schottky diode is integrated into the existing circuit topology, where the word line serves as one electrode of the Schottky diode and the bit line as the other. This merging approach minimizes additional structural complexity while achieving the desired reliability improvement.
Solution Approach 2:
The Schottky diode performs multiple functions within the OTP memory cell: it blocks reverse leakage currents during programming, controls electric field distribution across the dielectric layer, and provides a rectifying junction for unidirectional current flow. This multi-functionality reduces the need for additional specialized components, thereby limiting the increase in device complexity while achieving reliable programming operation.
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 integration of Schottky diodes enhances programming reliability and reduces leakage currents, improving the overall performance and data retention capabilities of OTP memory cells.
Implementation Method 1
Incorporating Schottky diodes between word lines and transistors in OTP memory cells, which allows for controlled programming and reading by blocking reverse leakage currents
Implementation Method 2
To program an anti-fuse bit, a programming electric field is applied across the dielectric material layer to sustainably alter (e.g., break down) the dielectric material, thus decreasing the resistance of the dielectric material layer
Data Source
AI summary
A memory device includes a substrate, a first transistor and a second transistor, a Schottky diode, a first word line, a second word line, and a bit line. The first transistor and the second transistor are over the substrate, wherein a first source/drain structure of the first transistor is electrically connected to a first source/drain structure of the second transistor. The Schottky diode is electrically connected to a gate structure of the first transistor. The first word line is electrically connected to the gate structure of the first transistor through the Schottky diode. The second word line is electrically connected to a gate structure of the second transistor. The bit line is electrically connected to a second source/drain structure of the second transistor.