Dielectric Interconnect Capping Structure for Coplanar Via Formation
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Solution Overview
Problem
The formation of interconnect structures in semiconductor devices is complicated by issues such as via loss and IMD dishing, which affect the reliability and performance of the semiconductor device due to the difficulty in forming metal lines and vias with precise alignment and material compatibility.
Innovation Solution
A capping structure is formed on metal lines using a dielectric material, such as silicon nitride, to prevent via loss and IMD dishing by ensuring that top vias and capping structures are coplanar, thereby maintaining consistent height and alignment during the IMD planarization process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a capping structure is formed on metal lines to prevent via loss and IMD dishing, then manufacturing precision and reliability are improved, but device complexity increases
Solution Approach 1:
The capping structure is formed on the metal lines before the IMD planarization process. This preliminary action ensures that the metal lines are protected and maintained at a consistent height throughout subsequent processing steps, preventing via loss and IMD dishing that would otherwise occur during planarization.
Solution Approach 2:
The capping structure acts as an intermediary element between the metal lines and the IMD layer. It provides a planar surface for the IMD to be deposited upon, while also protecting the underlying metal lines from damage during the IMD formation process, thus resolving the conflict between achieving precision and managing complexity.
2Reliability
If top vias and capping structures are made coplanar to maintain consistent height, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The formation of top vias and capping structures is merged into a single patterning step. By using the same etch process and masking layer for both features, the patent ensures they are formed at the same height and remain coplanar, improving reliability while avoiding the need for separate processing steps that would increase complexity.
Solution Approach 2:
The patent controls the etch depth and masking parameters to ensure that both top vias and capping structures are formed to the same depth, making them coplanar. This parameter control maintains consistent height without requiring additional complex processing steps.
3Manufacturing precision
If different dielectric materials are used for capping structure and isolation structure, then manufacturing precision is improved, but material compatibility challenges arise
Solution Approach 1:
Different dielectric materials are used in different locations: a first dielectric material for the capping structure on metal lines and a second dielectric material for the isolation structure surrounding them. Each material is selected for its specific local function, with the capping material optimized for planarization precision and the isolation material optimized for electrical isolation and mechanical properties.
Solution Approach 2:
The patent employs a composite interconnect structure with multiple dielectric materials. The capping structure uses a dielectric material that provides good planarization characteristics, while the isolation structure uses a different dielectric material that provides excellent electrical isolation. This composite approach allows each material to be optimized for its specific function, improving overall manufacturing precision despite the added material complexity.
Data Source
AI summary
Provided is a semiconductor device which includes: a base layer; a 1st metal line on the base layer; a 1st capping structure on the 1st metal line; and an isolation structure surrounding the 1st metal line and the 1st capping structure, wherein the isolation structure and the 1st capping structure comprise different dielectric materials.