Multilayer Metal Photoresist Patterning for EUV Line Width Control
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Solution Overview
Problem
The challenge of reducing semiconductor feature size and maintaining process windows in photolithographic processing has become increasingly difficult due to tighter process windows and issues such as uneven exposure and outgassing of metal-containing photoresists, leading to defects and poor line width roughness in extreme ultraviolet lithography.
Innovation Solution
A multilayer photoresist structure is formed with layers having different physical parameters, which undergo selective exposure and heating to enhance crosslinking, followed by development to create a precise pattern, addressing uneven exposure and outgassing issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If metal-containing photoresist is used in EUVL to form smaller semiconductor features, then device density and feature size reduction are improved, but outgassing occurs leading to defects and poor line width roughness
Solution Approach 1:
The photoresist is divided into multiple layers with different metal concentrations. The first photoresist layer has a first concentration of metal-containing compounds, and the second photoresist layer has a second concentration of metal-containing compounds that is different from the first concentration. This segmentation allows different regions of the photoresist to have different outgassing characteristics, reducing overall line width roughness while maintaining the ability to form small features.
Solution Approach 2:
Different layers of the photoresist are assigned different local qualities in terms of metal concentration. The first photoresist layer and second photoresist layer have distinct metal concentrations tailored to their specific functions in the exposure and development process. This local differentiation optimizes both the patterning performance and reduces harmful outgassing effects.
2Manufacturing precision
If photolithographic processing is used to reduce device size, then device density is improved, but process windows become tighter leading to manufacturing challenges
Solution Approach 1:
The photoresist structure is made dynamic through the use of multiple layers with different metal concentrations that respond differently to exposure and development conditions. This multi-layer dynamic structure allows for better control over the patterning process, effectively widening the process window despite the demand for smaller feature sizes.
Solution Approach 2:
The photoresist is formulated as a composite material system with multiple layers containing different concentrations of metal-containing compounds. This composite structure combines the benefits of metal-enhanced sensitivity and resolution with reduced outgassing, thereby improving manufacturing precision while managing process complexity.
3Productivity
If exposure power or resist photo speed is increased to improve wafer exposure throughput, then productivity is improved, but line width roughness and defects increase
Solution Approach 1:
The metal concentration parameter is varied between the first and second photoresist layers. By optimizing the specific concentrations of metal-containing compounds in each layer, the photoresist achieves improved sensitivity and photo speed, enabling higher throughput exposure while maintaining smooth line widths and reducing defects through controlled chemical reactions during development.
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 multilayer photoresist structure improves line width roughness and critical dimension uniformity, reducing defects and enhancing the precision of semiconductor features.
Implementation Method 1
The multilayer photoresist structure is selectively exposed to actinic radiation to form a latent pattern
Implementation Method 2
The selectively exposed multilayer photoresist structure is heated to enhance crosslinking
Implementation Method 3
The latent pattern is developed by applying developer to the selectively exposed multilayer photoresist structure to form the pattern
Data Source
AI summary
A method of manufacturing semiconductor device includes forming a multilayer photoresist structure including a metal-containing photoresist over a substrate. The multilayer photoresist structure includes two or more metal-containing photoresist layers having different physical parameters. The metal-containing photoresist is a reaction product of a first precursor and a second precursor, and each layer of the multilayer photoresist structure is formed using different photoresist layer formation parameters. The different photoresist layer formation parameters are one or more selected from the group consisting of the first precursor, an amount of the first precursor, the second precursor, an amount of the second precursor, a length of time each photoresist layer formation operation, and heating conditions of the photoresist layers. The multilayer photoresist structure is selectively exposed to actinic radiation to form a latent pattern, and the latent pattern is developed by applying developer to the selectively exposed multilayer photoresist structure to form the pattern.