Air Gap Structure Integration via Dry Etching and Vacuum Liner Deposition
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Solution Overview
Problem
Conventional wet etching techniques for forming air gap structures in integrated circuit interconnects can damage conductive and barrier layers, leading to oxidation and degradation of electrical performance due to long queue times between etching and subsequent processes.
Innovation Solution
A method involving dry etching of the mold layer in a vacuum processing system to expose interconnects without breaking vacuum, followed by deposition of a thin liner layer to prevent oxidation and maintain structural integrity, allowing for the formation of an air gap structure without damaging the conductive or barrier layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet etching technique is used to remove the mold layer, then the mold layer can be selectively removed to form air gap structures, but the conductive material and barrier layer are damaged and oxidized
Solution Approach 1:
The patent applies dry etching instead of wet etching to perform the mold layer removal in a controlled environment that prevents oxidation. The dry etching process uses a plasma environment or chemical vapor deposition chamber that maintains an inert atmosphere, thereby protecting the copper interconnect and barrier layer from oxidation while still achieving selective mold layer removal.
Solution Approach 2:
The patent replaces the chemical wet etching process with a physical/chemical dry etching process. Instead of using liquid etchants that cause damage, the invention uses plasma-based or vapor-phase etching methods that provide more controlled and selective removal of the mold layer without the harmful side effects of wet chemistry on the underlying conductive and barrier layers.
2Productivity
If long queue times are allowed between mold wet etching and subsequent processes, then process scheduling flexibility is improved, but oxidation of conductive material and barrier layer occurs
Solution Approach 1:
The patent implements a continuous processing sequence where the dry etching of the mold layer is immediately followed by deposition of the liner and air gap formation materials without breaking vacuum or exposing the structure to ambient air. This continuous operation eliminates the queue time that would otherwise allow oxidation, while the integrated processing system maintains productivity through streamlined workflow.
Solution Approach 2:
The patent maintains an inert or vacuum environment throughout the entire sequence from mold layer removal through air gap formation. By keeping the processing chamber under vacuum or inert atmosphere without breaking vacuum between steps, the conductive material and barrier layer are protected from oxidation even during extended processing sequences.
3Ease of manufacture
If wet etching is used to remove the mold layer, then the air gap structure can be formed, but the barrier layer and conductive material are physically damaged
Solution Approach 1:
The patent uses dry etching in a controlled plasma or vapor environment to remove the mold layer with high selectivity and precision. This method allows the air gap structure to be formed while maintaining the integrity of the barrier layer and conductive material, as the dry etching process can be tuned to etch only the mold layer without attacking the underlying sensitive layers.
Solution Approach 2:
The patent replaces the chemical attack mechanism of wet etching with a more controlled physical/chemical process of dry etching. This substitution enables precise removal of the mold layer through plasma or vapor-phase reactions that are highly selective and can be stopped exactly when the mold layer is removed, preventing physical damage to the barrier layer and conductive material.
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 prevents damage and oxidation of the interconnects and barrier layers, enhancing the electrical robustness and integrity of the integrated layer stack by maintaining the vacuum environment throughout the process, reducing queue times and improving overall performance.
Implementation Method 1
dry etching a mold layer disposed on the integrated layer stack in a processing system under vacuum
Implementation Method 2
depositing a liner layer over the exposed portion of the one or more interconnects
Data Source
AI summary
A method for forming an air gap structure in an integrated layer stack includes dry etching a mold layer disposed on the stack in a processing system under vacuum. The mold layer is disposed between one or more interconnects, and the process of dry etching of the mold layer exposes at least a portion of the interconnects. The method also includes depositing a liner layer over the exposed portion of the interconnects. In another embodiment, a method for forming an air gap structure in an integrated layer stack includes dry etching an oxide mold layer disposed on the stack in an a first processing chamber in a processing system under vacuum. The method also includes depositing a low-k material liner layer over the interconnects, wherein the liner has a thickness of less than about 2 nanometers. The methods disclosed herein are performed in a processing system without breaking vacuum.