Selective Deposition of Nickel Oxide Memory Cells
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Solution Overview
Problem
Fabricating memory devices from rewriteable resistivity-switching materials is difficult due to their chemical etchability, which increases fabrication costs and complexity in integrated circuits.
Innovation Solution
A selective deposition process is used to form reversible resistance-switching elements, such as nickel oxide, without the need for etching, by depositing nickel-containing layers only on conductive surfaces and then oxidizing them, simplifying the fabrication of memory cells and eliminating the need for etching of these materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If rewriteable resistivity-switching materials are used in memory devices, then memory functionality is achieved, but fabrication complexity and costs increase due to chemical etching requirements
Solution Approach 1:
The patent extracts the etching step from the fabrication process by using selectively deposited nickel oxide layers that do not require chemical etching. The nickel oxide is deposited only on conductive surfaces through selective deposition, eliminating the need for subsequent etching operations and thereby reducing fabrication complexity.
Solution Approach 2:
The patent replaces the chemical etching process with a physical deposition process. Instead of using chemical etchants to remove material, the nickel oxide layer is selectively deposited onto conductive surfaces using physical vapor deposition or similar techniques, substituting a mechanical/physical process for a chemical one.
2Manufacturing precision
If nickel and nickel oxide layers are deposited and etched in integrated circuits, then reversible resistance-switching elements are formed, but fabrication costs and process complexity increase
Solution Approach 1:
The nickel oxide layer performs dual functions: it serves as both the reversible resistance-switching material and as a self-aligned patterned layer. The selective deposition ensures the material is placed only where conductive surfaces exist, making the layer self-patterned and eliminating the need for separate photolithography and etching steps to define its location.
Solution Approach 2:
The nickel oxide layer serves multiple functions simultaneously: it provides the reversible resistance-switching functionality, acts as a self-aligned patterned structure, and eliminates the need for separate etching processes. This multi-functionality reduces the overall number of fabrication steps required.
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 simplifies the fabrication of memory cells by eliminating the etching process for nickel and nickel oxide layers, reducing complexity and costs, while enabling the use of difficult-to-etch materials like nickel oxide in memory devices.
Implementation Method 1
a selective deposition process is used to form reversible resistance-switching elements, such as nickel oxide, without the need for etching, by depositing nickel-containing layers only on conductive surfaces
Implementation Method 2
by depositing nickel-containing layers only on conductive surfaces and then oxidizing them
Data Source
AI summary
A memory cell is provided that includes a steering element, a reversible resistance-switching element coupled to the steering element and a silicide-forming metal layer disposed between the steering element and the reversible resistance-switching element. The reversible resistance-switching element includes tantalum, and is formed using a selective deposition process. Numerous other aspects are provided.