SiC-Rich Cap Layer for Cobalt Contamination Control
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Solution Overview
Problem
Current semiconductor fabrication techniques face challenges in preventing contamination of conductive features, particularly from cobalt in capping layers, which can lead to time-dependent dielectric breakdown and electromigration issues in low dielectric constant materials.
Innovation Solution
A protective SiC-rich cap layer is formed over conductive features to prevent contamination from cobalt and other materials during the capping process, using a single or dual damascene process, ensuring the integrity of low-k dielectric materials and reducing electromigration risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capping layer is formed over conductive features to improve electromigration resistance, then reliability is improved, but contamination of low-k dielectric materials occurs leading to time-dependent dielectric breakdown
Solution Approach 1:
A SiC-rich cap layer is introduced as an intermediary barrier between the cobalt capping layer and the low-k dielectric material. This intermediate layer prevents direct contact and contamination while allowing the capping process to proceed, thus maintaining electromigration resistance without causing dielectric breakdown
Solution Approach 2:
The capping structure is segmented into multiple functional layers: a SiC-rich cap layer for contamination prevention and a separate cobalt capping layer for electromigration protection. This segmentation allows each layer to perform its specific function without interfering with the other, resolving the contradiction between protection and contamination
2Reliability
If conventional capping processes are used to protect conductive features, then electromigration resistance is improved, but dielectric breakdown occurs due to contamination
Solution Approach 1:
The SiC-rich cap layer serves as a mediator that preserves dielectric integrity by blocking cobalt contamination while allowing the capping process to provide electromigration resistance. This mediator layer maintains the stability of the dielectric composition throughout the device structure
3Reliability
If cobalt capping is applied to reduce electromigration, then conductor reliability is improved, but time-dependent dielectric breakdown is induced
Solution Approach 1:
The capping system is divided into two separate layers with distinct functions: the SiC-rich cap layer prevents dielectric breakdown by blocking contamination, while the cobalt layer provides electromigration resistance. This segmentation eliminates the harmful interaction between cobalt and dielectric materials while maintaining conductor reliability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The SiC-rich cap layer effectively prevents contamination, enhancing the reliability of conductive features by reducing cobalt contamination by over 90% and improving breakdown voltage, thus addressing the issues of time-dependent dielectric breakdown and electromigration.
Implementation Method 1
A protective material is formed proximate conductive features to prevent contamination of a material layer proximate the conductive features from a subsequently formed capping layer
Data Source
AI summary
Semiconductor devices, methods of manufacture thereof, and methods of forming conductive features thereof are disclosed. A semiconductor device includes an insulating material layer disposed over a workpiece. The insulating material layer includes a silicon-containing material comprising about 13% or greater of carbon (C). A conductive feature is disposed within the insulating material layer. The conductive feature includes a capping layer disposed on a top surface thereof.