Top Via Damascene Structure for Tight-Pitch Interconnects
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Solution Overview
Problem
As devices miniaturize, forming vias at acceptable pitches in lower metallization layers becomes increasingly difficult due to the challenges in creating skip vias and maintaining structural integrity and connectivity between conductive lines.
Innovation Solution
A method involving the formation of sacrificial trench and channel layers, conductive plugs, and barrier layers within the interlayer dielectric to create a top via structure that allows for the use of different conductive materials for vias and lines, enabling precise patterning and alignment, and conformal deposition of dielectric barrier materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If devices are miniaturized to achieve smaller dimensions, then device density and integration are improved, but forming vias at acceptable pitches becomes more difficult
Solution Approach 1:
The via formation process is divided into multiple stages: first forming a trench and filling it with conductive material, then depositing a dielectric layer, and finally forming a channel through the dielectric to create the via. This segmentation allows each step to be optimized independently, making miniaturization feasible
Solution Approach 2:
The conductive trench plug is formed in advance before the dielectric layer is deposited. This preliminary action establishes the via structure early in the process, allowing subsequent layers to be built around it and enabling better control over final via dimensions and alignment
2Quantity of substance
If pitch is reduced to increase device density, then integration is improved, but structural integrity and connectivity of vias deteriorate
Solution Approach 1:
Different materials with optimized properties are used in different regions: a conductive material for the trench plug, a dielectric material for the surrounding layer, and potentially different conductive materials for the channel plug. This local optimization maintains via integrity even at reduced pitches
Solution Approach 2:
The via structure comprises multiple materials including conductive trench plug material, dielectric material, and conductive channel plug material. This composite structure provides both mechanical support and electrical functionality, enhancing reliability at small pitches
3Adaptability or versatility
If different conductive materials are used for vias and lines, then functionality is improved, but process complexity increases
Solution Approach 1:
The conductive structure is segmented into a trench plug portion and a channel plug portion, allowing different materials to be deposited at different stages. This segmentation enables material optimization for each function while managing process complexity through standardized deposition techniques
Solution Approach 2:
The process allows changing material parameters (conductivity, deposition method, thickness) between the trench plug and channel plug stages. This parameter flexibility enables optimization for specific applications while using established semiconductor manufacturing processes
Data Source
AI summary
A method of forming a top via is provided. The method includes forming a sacrificial trench layer and conductive trench plug in an interlayer dielectric (ILD) layer on a conductive line. The method further includes forming a cover layer on the ILD layer, sacrificial trench layer, and conductive trench plug, and forming a sacrificial channel layer and a conductive channel plug on the conductive trench plug. The method further includes removing the cover layer and the ILD layer to expose the sacrificial trench layer and the sacrificial channel layer. The method further includes removing the sacrificial trench layer and the sacrificial channel layer, and forming a barrier layer on the conductive channel plug and conductive trench plug.