Memory Cell With High-k Dielectric Contact Etch Stop Layer
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Solution Overview
Problem
Current non-volatile memory technologies, such as PROMs, are not reprogrammable and rely on fuses or anti-fuses for data storage, which face challenges in maintaining data retention due to oxide breakdown and high current spikes during programming, leading to limited retention time and efficiency.
Innovation Solution
The use of a transistor as a fuse or anti-fuse, with a contact etch stop layer incorporating high-k dielectric materials to improve electron capture and reduce bit cell current degradation, combined with a selector transistor to control programming voltage and duration, enhancing retention time and programming efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fuses or anti-fuses are used for data storage in non-volatile memory, then data retention is achieved, but oxide breakdown and high current spikes occur during programming leading to limited retention time
Solution Approach 1:
The patent changes the material parameter of the contact etch stop layer from conventional low-k dielectric to high-k dielectric material. This parameter change increases the layer's electron capture capability, which directly addresses the oxide breakdown issue by capturing stray electrons that would otherwise cause breakdown, thereby extending retention time while maintaining data storage reliability.
Solution Approach 2:
The patent employs a composite structure by integrating high-k dielectric material into the contact etch stop layer, creating a multi-functional layer that combines etch stop functionality with enhanced electron capture properties. This composite approach allows simultaneous achievement of reliable programming (by stopping etching) and extended retention (by capturing electrons and preventing oxide breakdown).
2Ease of manufacture
If conventional contact etch stop layers are used, then fabrication process is simple, but electron capture capability is insufficient leading to oxide breakdown and current spikes
Solution Approach 1:
The patent modifies the dielectric constant parameter of the contact etch stop layer by selecting high-k dielectric material. This single parameter change enhances electron capture capability without fundamentally altering the fabrication process flow, thus maintaining ease of manufacture while significantly improving reliability by preventing oxide breakdown through enhanced electron trapping.
3Reliability
If high programming currents are applied to program fuses, then data storage is achieved, but bit cell current degradation occurs reducing programming efficiency
Solution Approach 1:
The high-k dielectric contact etch stop layer acts as an intermediary that captures stray electrons generated during programming. By intercepting these electrons before they cause oxide breakdown, the layer enables more efficient programming with reduced current requirements, thereby improving programming efficiency while maintaining reliable data storage.
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 increases the retention time of memory cells by effectively managing programming voltages and currents, reducing oxide breakdown, and improving data storage reliability in non-volatile memory arrays.
Implementation Method 1
The contact etch stop layer includes a high-k dielectric layer for improving the ability of capturing the electrons
Data Source
AI summary
A memory cell includes a selector, a fuse connected to the selector in series, a contact etch stop layer formed on the selector and the fuse, a bit line connected to the fuse, and a word line connected to the selector. The contact etch stop layer includes a high-k dielectric for improving the ability of capturing the electrons, thus the retention time of the memory cell is increased.