OTP Memory Cell Structure for Reliable Dielectric Breakdown
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Solution Overview
Problem
Existing one-time programmable (OTP) memory cells in integrated circuits face challenges in reliably and consistently destroying the insulating layer during programming operations, leading to inconsistent data storage and reading.
Innovation Solution
The OTP memory cell design incorporates a thinner insulating layer for the first transistor and a nanosheet structure for the second transistor, with specific voltage conditions during programming and reading operations to ensure reliable breakdown of the insulating layer, allowing for consistent data storage and retrieval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional insulating layer is used in OTP memory cells, then the structure is simpler to manufacture, but the breakdown reliability during programming is inconsistent
Solution Approach 1:
The patent applies local quality by creating a multi-layer insulating structure where different layers have different dielectric properties. Specifically, it uses a first insulating layer with a first dielectric constant and a second insulating layer with a second dielectric constant, where the dielectric constants are different. This allows the programming voltage to be distributed non-uniformly across the layers, concentrating the electric field in a specific layer to achieve reliable breakdown at a controlled location while maintaining overall structural integrity.
Solution Approach 2:
The patent employs composite materials by combining multiple insulating layers with different dielectric characteristics into a single insulating structure. This composite approach enables the system to achieve both reliability (through controlled breakdown in the appropriate layer) and manufacturability (by using standard dielectric materials that can be deposited using conventional semiconductor fabrication processes).
2Reliability
If the insulating layer is made thinner to reduce breakdown voltage, then programming becomes easier, but data retention reliability decreases
Solution Approach 1:
The patent applies parameter changes by modifying the dielectric constant parameter of the insulating layers rather than simply changing the physical thickness. By selecting materials with appropriate dielectric constants and arranging them in specific configurations, the patent achieves the desired electric field distribution and breakdown characteristics without compromising data retention reliability. This allows programming at lower voltages while maintaining sufficient thickness for reliable data storage.
3Reliability
If a multi-layer insulating structure is implemented, then breakdown reliability improves, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-designing the multi-layer insulating structure with specific thickness ratios and dielectric constant relationships before fabrication. The design criteria specify that the product of thickness and dielectric constant for each layer should be within defined ranges, which guides the fabrication process. This preliminary design approach enables standard manufacturing processes to produce the complex multi-layer structure with consistent results, reducing actual fabrication complexity.
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 enhances the reliability of programming and reading operations, improving data retention and reducing power consumption by increasing electron mobility and reducing breakdown voltage.
Implementation Method 1
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 first word line, a second word line, and a bit line. The first transistor and the second transistor are over the substrate and are electrically connected to each other, in which each of the first and second transistors includes first semiconductor layers and second semiconductor layers, a gate structure, and source/drain structures, in which the first semiconductor layers are in contact with the second semiconductor layers, and a width of the first semiconductor layers is narrower than a width of the second semiconductor layers. The first word line is electrically connected to the gate structure of the first transistor. The second word line is electrically connected to the gate structure of the second transistor. The bit line is electrically connected to a first one of the source/drain structures of the first transistor.