Multi-Layer Bottom Electrode for RRAM Gap Fill
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Solution Overview
Problem
As RRAM cells shrink in size, the bottom electrode metal often fails to properly fill the dielectric layer, resulting in non-planar topographies that negatively affect data storage and reliability.
Innovation Solution
A multi-layer bottom electrode with an insulating core is used, where a conductive lower BE layer is surrounded by an insulating BE layer, which fills gaps better than conductive materials, providing a planar surface for the dielectric data storage layer and top electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the bottom electrode metal is used to fill the dielectric layer, then the RRAM cell structure is formed, but the filling becomes inadequate as cell size shrinks, resulting in non-planar topographies
Solution Approach 1:
The bottom electrode is divided into multiple conductive layers (first conductive bottom electrode layer and second conductive bottom electrode layer) separated by an insulating layer. This segmentation allows each layer to be optimized for different functions: the first layer provides electrical connection while the second layer forms a planar surface for the dielectric data storage layer, resolving the contradiction between filling quality and reliability.
Solution Approach 2:
An insulating layer is introduced as an intermediary between the two conductive bottom electrode layers. This insulating layer fills the gaps effectively and provides a planarizing effect, enabling the upper dielectric layer to be deposited uniformly. The intermediary layer resolves the filling issue without compromising the electrical functionality of the bottom electrode.
2Device complexity
If a single-layer conductive bottom electrode is used, then the structure is simple, but it cannot provide both electrical connection and planar surface for dielectric layer
Solution Approach 1:
The bottom electrode is segmented into multiple conductive layers with an insulating layer in between. The first conductive layer maintains electrical connectivity while the second conductive layer, positioned above the insulating layer, provides a planar surface for dielectric layer deposition. This segmentation enables the electrode to fulfill both electrical and planarizing functions.
Solution Approach 2:
Different regions of the bottom electrode structure are assigned different functions: the first conductive layer is optimized for electrical connection, while the second conductive layer is optimized for providing a planar surface. The insulating layer is specifically designed to fill gaps and enable planarization. This local differentiation of quality and function resolves the contradiction between structural simplicity and surface planarity.
Data Source
AI summary
The present disclosure relates to a memory cell having a multi-layer bottom electrode with an insulating core that provides for good gap fill ability, and an associated method of formation. In some embodiments, the memory cell includes a bottom electrode having an insulating material surrounded by a conductive material. A dielectric data storage layer is arranged over the bottom electrode, and a top electrode is arranged over the dielectric data storage layer.