EUV Mask Stack Processing via Surface Activation
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Solution Overview
Problem
Extreme ultraviolet (EUV) mask processing faces challenges in efficiently removing layers without photoresist patterning loss, leading to issues like breaks in resist templates that can result in shorts or open circuits during device fabrication.
Innovation Solution
A method involving the formation of resist templates on an upper hardmask layer, followed by a dry etch process to modify and activate the surfaces, allowing for the exposure of an underlying organic planarization layer without photoresist patterning loss, using a gas phase hardmask etch that is highly selective to photoresist material and effective for high aspect ratio features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional photoresist patterning is used for EUV mask processing, then layer removal can be achieved, but breaks in resist templates occur leading to patterning loss
Solution Approach 1:
The method performs preliminary actions by forming a protective capping layer over the resist template before the etch process, and pre-modifying the hardmask surface to enhance etch selectivity. This allows the resist template to be protected during subsequent processing steps, preventing breaks while maintaining patterning fidelity.
Solution Approach 2:
The patent introduces a capping layer as an intermediary protective element between the resist template and the etch environment. This capping layer acts as a mediator that shields the resist template from damage during hardmask removal, allowing aggressive etching conditions to be used without compromising template integrity.
2Productivity
If aggressive etching is used to remove EUV pattern stacks, then processing speed increases, but photoresist patterning loss increases
Solution Approach 1:
The patent changes the physical and chemical parameters of the etch process by introducing oxygen plasma treatment to modify the hardmask surface properties. This creates a more etch-friendly surface that allows faster removal rates while maintaining better selectivity and reducing side-etch that would compromise patterning accuracy.
Solution Approach 2:
The method performs preliminary oxygen plasma treatment on the hardmask surface before the main etch process. This preliminary action modifies the surface chemistry to enhance etch rate and selectivity, enabling faster processing without sacrificing patterning precision in the subsequent etching steps.
3Reliability
If multiple processing steps are used to remove EUV layers, then complete layer removal is achieved, but process complexity increases
Solution Approach 1:
The patent merges multiple functions into a single integrated process flow. The oxygen plasma treatment serves dual purposes of surface modification and contamination removal, while the capping layer simultaneously protects the resist template and provides a controlled etch interface. This consolidation reduces the number of separate processing steps while maintaining complete layer removal.
Solution Approach 2:
The capping layer serves multiple functions: it protects the resist template from damage, provides a controlled interface for selective etching, and can be selectively removed after serving its protective function. This multi-functionality allows a single layer to replace what would otherwise require multiple separate processing interventions.
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 enables the removal of EUV pattern stacks with reduced photoresist patterning loss, preventing breaks in resist templates and ensuring accurate device fabrication by maintaining the integrity of the resist templates during the etching process.
Implementation Method 1
exposing portions of the surface of the upper hardmask layer to a dry etch process to produce modified and activated surfaces
Data Source
AI summary
A method of removing layers of an extreme ultraviolet (EUV) pattern stack is provided. The method includes forming one or more resist templates on an upper hardmask layer. The method further includes exposing portions of the surface of the upper hardmask layer to a dry etch process to produce modified and activated surfaces. The method further includes etching the modified and activated surfaces to expose an underlying organic planarization layer.