Conductive Interconnect Cavity Structure for Uniform Memory Contacts
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Solution Overview
Problem
The increasing integration of memory in integrated circuits leads to challenges in making suitable connections to tightly-packed wordlines and bitlines, with issues such as shorting and non-uniform resistance across interconnects, which affect the performance and reliability of memory arrays.
Innovation Solution
The development of conductive interconnects comprising a conductive liner and core, where the core is substantially aligned with the conductive lines, and the formation of a recessed cavity with an insulative spacer to ensure consistent and low-resistance interfaces, reducing the risk of shorting and enhancing uniformity across the array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If wordlines and bitlines are tightly packed to increase integration level, then memory density increases, but the risk of shorting between lines and interconnects increases
Solution Approach 1:
An insulative spacer is introduced as an intermediary element between the conductive interconnect and the wordlines/bitlines. This spacer physically separates the conductive elements, preventing direct contact and shorting while allowing the interconnect to maintain electrical contact with the target line through a controlled interface. The insulative spacer acts as a mediator that enables tight packing without compromising reliability.
Solution Approach 2:
The interconnect structure is segmented into distinct functional regions: a conductive portion for electrical contact, an insulative spacer portion for isolation, and a recessed cavity for precise alignment. This segmentation allows each region to perform its specific function independently, enabling both high density and low shorting risk.
2Reliability
If the conductive core is made larger to reduce resistance, then electrical performance improves, but misalignment with target lines becomes more problematic
Solution Approach 1:
The interconnect structure employs local quality by having different regions with different properties: the conductive core provides low resistance through its material composition and cross-sectional area, while the insulative spacer provides precise lateral confinement and alignment. The recessed cavity at the top surface creates a localized alignment feature that ensures precise registration with the target line, allowing the larger conductive core to maintain both low resistance and high alignment precision.
3Ease of manufacture
If a simple conductive plug structure is used, then fabrication is easier, but resistance uniformity across the array becomes non-uniform
Solution Approach 1:
The recessed cavity is formed in advance before the conductive interconnect is deposited. This preliminary action creates a pre-defined alignment feature and controlled interface geometry that ensures uniform resistance across all interconnects in the array. By establishing the cavity structure beforehand, the subsequent deposition process can be performed with standard techniques while achieving consistent electrical characteristics.
4Ease of operation
If the interconnect extends deeply through the insulative mass, then connection to underlying circuitry is achieved, but alignment precision with target lines becomes more difficult
Solution Approach 1:
The alignment problem is solved by transitioning from a purely lateral alignment approach to a multi-dimensional solution. The recessed cavity provides vertical confinement and lateral positioning, creating a three-dimensional alignment feature that guides the conductive interconnect to the correct position. This dimensional approach allows deep extension through the insulative mass while maintaining precise alignment with the target wordline or bitline.
Data Source
AI summary
Some embodiments include a method of forming an integrated assembly. An arrangement is formed to include a conductive pillar extending through an insulative mass. An upper surface of the conductive pillar is recessed to form a cavity. An insulative collar is formed within the cavity to line an outer lateral periphery of the cavity. A recessed surface of the conductive pillar is exposed at a bottom of the lined cavity. A conductive expanse is formed over the insulative mass. A portion of the conductive expanse extends into the cavity and is configured as an interconnect. The conductive expanse is patterned into multiple conductive structures. One of the conductive structures includes the interconnect.