Vacuum Interconnect Capping for Oxidation-Free Dielectric Deposition
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Solution Overview
Problem
In semiconductor manufacturing, the reduction of IC component dimensions to sub-micron levels requires improved methods for forming interconnection structures with copper wires, as conventional processes lead to oxidation of metal cap layers and damage to underlying layers due to exposure to ambient environments during the deposition of dielectric layers.
Innovation Solution
A cluster tool is designed with integrated pre-clean, selective CVD, and PECVD chambers that allow for the formation of interconnection structures without exposure to ambient environments, enabling pre-cleaning, selective cap layer deposition, and blanket dielectric layer deposition in a vacuum, thereby avoiding contamination and improving adhesion and electromigration performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a dielectric layer is deposited in a different cluster tool from the metal cap layer deposition, then queue times can be managed, but the metal cap layer oxidizes during transfer via nitrogen-purged FOUP
Solution Approach 1:
The patent merges the pre-clean chamber, selective CVD chamber, and PECVD chamber into a single integrated cluster tool. This allows the metal cap layer deposition, pre-cleaning, and dielectric layer deposition to occur in sequence within the same vacuum environment, eliminating the need for intermediate transfers and preventing oxidation while maintaining efficient queue time management.
Solution Approach 2:
The patent maintains a continuous vacuum environment throughout the entire process sequence. By keeping all processing steps within the sealed cluster tool chambers and avoiding exposure to ambient atmosphere (even nitrogen-purged FOUP), the metal cap layer remains protected from oxidation during transfers and queue times.
2Reliability
If a pre-cleaning process is performed on the metal cap layer, then oxidation can be removed, but underlying layers are damaged
Solution Approach 1:
The patent employs a plasma-based pre-cleaning process with carefully controlled parameters (power, pressure, gas composition, and exposure time) that selectively removes oxidation from the metal cap layer surface while the underlying layers remain protected. The plasma treatment parameters are optimized to achieve complete oxide removal without causing damage to the copper interconnect or other sensitive underlying structures.
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
This approach enhances the adhesion of dielectric layers on metal cap layers, improves electromigration performance, and extends the time-dependent dielectric breakdown lifetime of low-k dielectric layers, eliminating the need for nitrogen-purged transfers and queue time control.
Implementation Method 1
performing a pre-clean process to remove oxides formed on an exposed surface of a metal layer
Implementation Method 2
performing a selective deposition process to deposit a cap layer on the pre-cleaned surface of the metal layer in a selective chemical vapor deposition (CVD) chamber
Implementation Method 3
performing a blanket deposition process to deposit a second dielectric layer on the cap layer and an exposed surface of the first dielectric layer in a plasma-enhanced CVD (PECVD) chamber
Data Source
AI summary
A cluster tool for forming an interconnection structure includes a pre-clean chamber, a selective chemical vapor deposition (CVD) chamber, a plasma-enhanced CVD (PECVD) chamber, one or more transfer chambers coupled to the pre-clean chamber, the selective CVD chamber, and the PECVD chamber, and configured to transfer the interconnection structure between the pre-clean chamber, the selective CVD chamber, and the PECVD chamber without breaking vacuum environment, and a controller configured to cause pre-cleaning of an exposed surface of a metal layer formed within a first dielectric layer of the interconnection structure in the pre-clean chamber, selective deposition of a cap layer on the pre-cleaned surface of the metal layer in the selective CVD chamber, and deposition of deposit a second dielectric layer on the cap layer and an exposed surface of the first dielectric layer in the PECVD chamber.