Dry Non-Plasma Capping Layer Removal for Low-k Dielectric Integrity
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Solution Overview
Problem
Low-k dielectric films in semiconductor manufacturing are prone to damage during processing, leading to undercuts and changes in electrical properties, which complicate metallization and barrier layer formation due to their reactivity and susceptibility to water absorption.
Innovation Solution
A dry non-plasma removal process is used to selectively remove the capping layer overlying the insulation dielectric, employing a self-limiting process involving chemical treatment with gases like HF and NH3, followed by thermal desorption to minimize damage and maintain the integrity of the low-k film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching and plasma ashing processes are used to pattern the dielectric layer, then the pattern transfer is achieved, but the low-k film surface becomes damaged and reactive
Solution Approach 1:
A capping layer is deposited over the low-k dielectric layer before patterning operations. This capping layer serves as a protective barrier that prevents damage to the low-k film surface during subsequent etching and plasma ashing processes, while still allowing the pattern to be transferred through it to the underlying dielectric layer.
2Reliability
If the damaged surface layer of the low-k film is removed, then the film integrity is improved, but an undercut forms beneath the hard mask or capping layer
Solution Approach 1:
The capping layer is removed after the pattern transfer is complete and before metallization begins. This timing ensures that the low-k film surface can be properly prepared (damaged layer removed) without the capping layer being present to cause undercut formation during subsequent processing steps.
3Reliability
If the capping layer is removed early, then the low-k film surface can be prepared, but the capping layer causes undercut during metallization
Solution Approach 1:
The capping layer is removed at the optimal moment in the process sequence - after pattern transfer is complete but before metallization begins. This timing allows the low-k film surface to be properly prepared while avoiding the undercut problem that would occur if the capping layer remained during metallization.
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 method effectively removes the capping layer without damaging the low-k insulation layer, reducing undercut formation and maintaining the electrical properties of the dielectric, thus facilitating smoother metallization and barrier layer formation.
Implementation Method 1
employing a self-limiting process involving chemical treatment with gases like HF and NH3
Implementation Method 2
followed by thermal desorption to minimize damage and maintain the integrity of the low-k film
Data Source
AI summary
A method for patterning an insulation layer and selectively removing a capping layer overlying the insulation layer is described. The method utilizes a dry non-plasma removal process. The dry non-plasma removal process may include a self-limiting process.