FeRAM Top Electrode Sidewall Spacer for Etching Residue
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Solution Overview
Problem
During the manufacture of ferroelectric random-access memory (FeRAM) cells, the etching process can cause conductive residue to redeposit on sidewalls, leading to shorts between the bottom and top electrodes, resulting in device failure.
Innovation Solution
A dielectric sidewall spacer structure is disposed along the outer sidewalls of the top electrode to prevent conductive residue from shorting the bottom electrode to the top electrode, improving the yield and reliability of FeRAM devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an etching process is used to remove portions of the top electrode layer, ferroelectric layer, and bottom electrode layer, then the desired pattern structure is achieved, but conductive residue redeposits on sidewalls causing electrical shorts between electrodes
Solution Approach 1:
A dielectric sidewall spacer structure is introduced as an intermediary element between the top electrode and bottom electrode. This spacer acts as a physical barrier that prevents conductive residue from bridging the electrodes, thereby eliminating the harmful effect of residue redeposition while preserving the etching process benefits
Solution Approach 2:
The dielectric sidewall spacer structure is formed prior to the etching process that removes the ferroelectric layer and bottom electrode layer. This preliminary formation of the protective spacer ensures that when etching occurs and conductive residue is generated, the spacer is already in place to prevent the residue from causing electrical shorts
Data Source
AI summary
Some embodiments relate to a ferroelectric random access memory (FeRAM) device. The FeRAM device includes a bottom electrode structure and a top electrode overlying the ferroelectric structure. The top electrode has a first width as measured between outermost sidewalls of the top electrode. A ferroelectric structure separates the bottom electrode structure from the top electrode. The ferroelectric structure has a second width as measured between outermost sidewalls of the ferroelectric structure. The second width is greater than the first width such that the ferroelectric structure includes a ledge that reflects a difference between the first width and the second width. A dielectric sidewall spacer structure is disposed on the ledge and covers the outermost sidewalls of the top electrode.