Anti-Fuse OTP Cell With Segmented Gate Insulator
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing anti-fuse type one time programmable (OTP) cells face challenges in distinguishing between programmed and unprogrammed cells due to soft breakdown, which results in high blowing resistance values and reliability issues during programming and reading operations.
Innovation Solution
The design includes a gate insulating film with varying thicknesses and a salicide layer configuration on the gate electrode, where hard breakdown is ensured by forming a wide current path through the gate insulating film, reducing the probability of soft breakdown and increasing the reliability of programming and reading operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional anti-fuse OTP cell structure is used, then the device can be programmed through dielectric breakdown, but soft breakdown may occur resulting in high blowing resistance values that make it difficult to distinguish programmed from unprogrammed cells
Solution Approach 1:
The gate insulating film is designed with different thicknesses in different regions: a first thickness in the transistor area and a second thickness (greater than the first) in the capacitor area. This local differentiation ensures that breakdown occurs preferentially in the thinner transistor area region, creating a distinct conductive path with lower resistance and enabling reliable distinction between programmed and unprogrammed cells.
Solution Approach 2:
The gate insulating film is segmented into two distinct regions with different thickness characteristics. The first gate insulating film region (thinner) is positioned under the transistor area, while the second gate insulating film region (thicker) is positioned under the capacitor area. This segmentation controls the breakdown location and characteristics to prevent soft breakdown.
2Ease of manufacture
If the gate insulating film thickness is reduced to facilitate breakdown, then programming can occur more easily, but the risk of soft breakdown increases resulting in unreliable cell state detection
Solution Approach 1:
Different regions of the gate insulating film have different thicknesses optimized for their specific functions. The thinner first gate insulating film in the transistor area facilitates reliable breakdown and conductive path formation, while the thicker second gate insulating film in the capacitor area prevents premature or soft breakdown, ensuring consistent hard breakdown behavior.
Solution Approach 2:
The gate insulating film thickness parameter is varied spatially across the device structure. By changing the thickness from the first value (thinner) in the transistor area to the second value (thicker) in the capacitor area, the patent optimizes both the ease of programming and the reliability of breakdown consistency.
3Device complexity
If a uniform gate insulating film structure is used, then the device structure is simpler, but the current path formation is narrow leading to high blowing resistance values
Solution Approach 1:
The gate insulating film structure is made non-uniform with different thickness regions tailored to specific functional requirements. The thinner first gate insulating film region under the transistor area promotes wider and more reliable current path formation during breakdown, reducing blowing resistance values and improving conductive path quality.
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 configuration stabilizes the programming process, allowing for clear differentiation between programmed and unprogrammed cells, maintaining low blowing resistance values even after reliability tests, and ensuring accurate read operations.
Implementation Method 1
a high dielectric field is applied to a dielectric material such as an oxide to allow a tunneling current to flow through the dielectric material. The flow of the tunneling current through the dielectric material causes a phenomenon called 'dielectric breakdown.'
Implementation Method 2
a high dielectric field is applied to a dielectric material such as an oxide to allow a tunneling current to flow through the dielectric material
Data Source
AI summary
An anti-fuse device includes a gate insulating film formed on a semiconductor substrate, a gate electrode formed on the gate insulating film, and a salicide layer formed on a first portion of the gate electrode such that a second portion of the gate electrode omits the salicide layer, wherein a hard breakdown of at least a portion of the gate insulating film at a time of programming the anti-fuse device.