Amorphous Carbon Hardmask Deposition and UV Curing for IC Etching
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Solution Overview
Problem
Amorphous carbon films used as hardmasks in integrated circuit fabrication face challenges with high compressive film stress, leading to pattern distortion and line breakage, especially at feature sizes below 20 nm, due to insufficient etch selectivity and line integrity issues.
Innovation Solution
A method involving the deposition of a low-hydrogen content amorphous carbon layer using a hydrocarbon source and diluent gas in a plasma-enhanced process, followed by UV curing, to achieve high film density and reduced compressive stress, enhancing etch selectivity and line integrity for sub 45 nm devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amorphous carbon film is densified to increase etch selectivity, then the etch selectivity is improved, but the compressive film stress increases causing line bending or breakage
Solution Approach 1:
The patent applies parameter changes by modifying the deposition temperature (200-700°C) and introducing a diluent gas during plasma-enhanced chemical vapor deposition to control the hydrogen content and film density. This resolves the contradiction by achieving high etch selectivity through controlled densification while managing compressive stress through optimized deposition parameters.
Solution Approach 2:
The patent creates a composite structure by forming an amorphous carbon layer with specific hydrogen content (5-20%) through controlled deposition. The composite nature of the carbon-hydrogen composition allows tuning of both etch selectivity and stress properties, resolving the trade-off between these two critical parameters.
2Reliability
If a thicker amorphous carbon hardmask is used to improve pattern protection, then the etch selectivity is improved, but the line bending and wiggling during etching increases
Solution Approach 1:
The patent changes the film properties by controlling deposition temperature and diluent gas flow to achieve optimal hydrogen content. This produces a hardmask with balanced mechanical properties that provides adequate pattern protection while minimizing line bending and wiggling, eliminating the need for thicker films.
Solution Approach 2:
The patent creates a replicated structure by forming a conformal amorphous carbon layer that accurately copies the underlying pattern geometry. The controlled film properties ensure that this copied structure maintains line integrity during etching while providing necessary pattern protection.
3Productivity
If the feature size is reduced to increase device density, then the device integration is improved, but the line breakage and pattern distortion increases
Solution Approach 1:
The patent applies parameter changes by optimizing deposition temperature (200-700°C) and diluent gas composition to create an amorphous carbon hardmask with tailored mechanical properties. This enables successful patterning at reduced feature sizes by minimizing line breakage and distortion, thereby improving device integration while maintaining pattern fidelity.
4Shape
If a thinner amorphous carbon hardmask is used to reduce compressive stress, then the line integrity is improved, but the etch selectivity decreases
Solution Approach 1:
The patent resolves this contradiction by changing the film composition parameters through controlled deposition. By adjusting temperature and diluent gas flow to achieve optimal hydrogen content (5-20%), the film achieves both adequate etch selectivity and reduced compressive stress, allowing thinner films with improved line integrity.
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 approach results in a hardmask with improved etch selectivity and line integrity, allowing for thinner films and controlled etching of smaller features without line wiggling or bending, effectively addressing the limitations of conventional amorphous carbon films.
Implementation Method 1
introducing a gas mixture comprising a hydrocarbon source and a diluent gas into a deposition chamber, generating a plasma from the gas mixture in the deposition chamber to form a low-hydrogen content amorphous carbon layer on the substrate
Implementation Method 2
exposing the substrate to UV radiation within the curing chamber at a curing temperature above about 200° C.
Data Source
AI summary
Embodiments described herein relate to a method for processing a substrate. In one embodiment, the method includes introducing a gas mixture comprising a hydrocarbon source and a diluent gas into a deposition chamber located within a processing system, generating a plasma from the gas mixture in the deposition chamber at a temperature between about 200° C. and about 700° C. to form a low-hydrogen content amorphous carbon layer on the substrate, transferring the substrate into a curing chamber located within the processing system without breaking vacuum, and exposing the substrate to UV radiation within the curing chamber at a curing temperature above about 200° C.