Titanium Nitride Foundation Layer for Ferroelectric Memory Contact Plugs
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Solution Overview
Problem
Conventional methods fail to achieve satisfactory crystal orientation and flatness of the lower electrode on contact plugs in ferroelectric memory devices, leading to suboptimal integration and performance of ferroelectric capacitors.
Innovation Solution
A method involving the formation of a foundation layer with a laminated composite of titanium nitride layers, where a first titanium layer is nitrided into a first titanium nitride layer and a second titanium layer is nitrided into a second titanium nitride layer, embedded in the recess of the contact plug, to control crystal orientation and flatten the surface, followed by polishing to expose the first titanium nitride layer on the interlayer insulating layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the recess is completely filled to achieve flatness, then the surface flatness is improved, but the etching load increases
Solution Approach 1:
The second titanium nitride layer is formed with excessive thickness (greater than recess depth) to ensure complete filling and surface flatness, but the polishing step removes the excess material, achieving the desired flatness while minimizing the actual material that remains and needs to be etched later
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 ensures improved crystal orientation and flatness of the ferroelectric layer, enhancing the ferroelectric characteristics and integration level of the capacitors, while minimizing etching load and oxidization issues.
Implementation Method 1
nitriding the first titanium layer into a first titanium nitride layer
Implementation Method 2
nitriding the second titanium layer into a second titanium nitride layer
Implementation Method 3
polishing a surface of the second titanium nitride layer
Data Source
AI summary
A method of manufacturing a ferroelectric memory device includes: forming an active element on a substrate; forming an interlayer insulating layer on the substrate; forming an opening on the interlayer insulating layer and forming a contact plug inside the opening; forming a foundation layer above the substrate; and laminating, on the foundation layer, a first electrode, a ferroelectric layer, and a second electrode. In this method, the forming of the foundation layer includes: forming a first titanium layer having a thickness less than a depth of a recess; nitriding the first titanium layer into a first titanium nitride layer; forming a second titanium layer on the first titanium nitride layer so as to at least partially fill the recess remaining on the contact plug; nitriding the second titanium layer into a second titanium nitride layer, and polishing a surface of the second titanium nitride layer.