Ti-rich TiN Bottom Electrode for CNT MIM Memory Yield
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Solution Overview
Problem
Manufacturing high-yield memory devices that include carbon nanotube (CNT) MIM stacks is challenging due to alterations in the bottom electrode material during CNT deposition, affecting device yield and electrical performance.
Innovation Solution
The formation of a CNT MIM stack using a titanium-rich TiN bottom electrode and TiC contacts between the CNT material and the electrodes, which improves device yield and reproducible electrical contact, is proposed. This involves depositing CNT material on a Ti-rich bottom electrode and performing an anneal at specific temperatures to form TiC contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional bottom electrode materials are used during CNT deposition, then the deposition process can be completed, but the bottom electrode material is altered which reduces device yield and electrical performance
Solution Approach 1:
A titanium-rich TiN layer is deposited on the bottom electrode before CNT deposition to prevent alteration of the underlying electrode material. This preliminary protective layer is formed in advance to avoid the harmful interaction between CNT deposition processes and the bottom electrode material.
Solution Approach 2:
The titanium-rich TiN layer acts as an intermediary between the bottom electrode and the CNT material. This intermediate layer prevents direct contact and harmful interaction during CNT deposition, while still allowing for subsequent formation of TiC contacts for proper electrical functionality.
2Reliability
If the bottom electrode material is protected during CNT deposition, then device yield and electrical performance are improved, but additional fabrication steps are required
Solution Approach 1:
The titanium-rich TiN layer serves multiple functions: it protects the bottom electrode during CNT deposition, provides a surface for TiC contact formation, and maintains electrical functionality. This multi-functional approach reduces the need for separate protective and contact layers, simplifying the overall fabrication process despite the additional initial deposition step.
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 use of Ti-rich TiN bottom electrodes and TiC contacts enhances device yield and electrical performance, leading to improved reliability and functionality of CNT-based memory devices.
Implementation Method 1
with annealing processes to enhance the CNT-to-electrode contact, improving device yield and reproducibility
Data Source
AI summary
A reversible resistance-switching metal-insulator-metal (MIM) stack is provided which can be set to a low resistance state with a first polarity signal and reset to a higher resistance state with a second polarity signal. The first polarity signal is opposite in polarity than the second polarity signal. In one approach, the MIM stack includes a carbon-based reversible resistivity switching material such as a carbon nanotube material. The MIM stack can further include one or more additional reversible resistivity switching materials such as metal oxide above and/or below the carbon-based reversible resistivity switching material. In another approach, a metal oxide layer is between separate layers of carbon-based reversible resistivity switching material.