Multi-Level Metallization Interconnect with Gouged Surfaces
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Solution Overview
Problem
Aggressive dimensional scaling at the 7 nm node has led to increased interconnect resistance and mechanical strength challenges in semiconductor structures, particularly with tungsten, while cobalt and other low resistivity metals face reliability concerns due to poor mechanical strength and stress migration issues.
Innovation Solution
A multi-level interconnect structure is formed with gouged upper surfaces and embedded in dielectric materials, featuring a contact structure and metallization layers with gouging features to enhance mechanical strength and reduce contact resistance, using a method that includes forming contact openings and metallization structures within interconnect dielectric materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If aggressive dimensional scaling is applied to reduce interconnect dimensions, then wiring flexibility and integration density are improved, but interconnect resistance increases significantly
Solution Approach 1:
The patent employs composite interconnect structures combining different materials (e.g., cobalt with ruthenium, tungsten with copper) to achieve optimal balance between low resistance and mechanical reliability. The composite approach allows each material to contribute its strengths: cobalt provides low resistance and scalability, while ruthenium adds mechanical strength and stress migration resistance.
Solution Approach 2:
The patent systematically varies material parameters including composition ratios, film thicknesses, and crystalline structures to optimize interconnect performance. By adjusting these parameters, the design achieves lower resistance while maintaining mechanical integrity at scaled dimensions.
2Manufacturing precision
If cobalt and other low resistivity metals are used for scaling liner/barrier films, then void-free gap fill and film scaling capability are improved, but mechanical strength and stress migration resistance deteriorate
Solution Approach 1:
The patent uses composite metal structures where cobalt (providing low resistance and good gap fill) is combined with stronger metals like ruthenium or tungsten. This composite approach maintains the manufacturing advantages of cobalt while compensating for its mechanical weaknesses through the stronger partner material.
Solution Approach 2:
The patent applies different material compositions and structures to different regions of the interconnect. For example, the liner/barrier layers may use cobalt for its deposition advantages, while the core interconnect region uses stronger materials to provide mechanical support and stress migration resistance.
3Strength
If thick high resistivity liner/barrier films are used with tungsten, then mechanical strength is improved, but scaling difficulty and defectivity increase
Solution Approach 1:
The patent replaces thick tungsten-based composite structures with thinner, more scalable material combinations. The use of cobalt and ruthenium allows for reduced film thickness while maintaining both mechanical strength and low resistance, enabling better scaling without the defectivity issues associated with thick tungsten liners.
Data Source
AI summary
A semiconductor structure is provided that includes a contact structure containing a gouged upper surface embedded in at least a middle-of-the-line (MOL) dielectric material, wherein the contact structure contacts an underlying doped semiconductor material structure. A first metallization structure containing a gouged upper surface is in contact with the gouged upper surface of the contact structure and embedded in a first interconnect dielectric material. A second metallization structure is in contact with the gouged upper surface of the first metallization structure and embedded at least within a second interconnect dielectric material.