EUV Pellicle DUV Reflectivity Mapping for DGL-Free Lithography
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Solution Overview
Problem
The challenge in EUV photolithography is the degradation of latent images due to deep ultraviolet (DUV) light interacting with EUV-sensitive photoresist, which can lead to defects in semiconductor devices, and the use of a dynamic gas lock (DGL) membrane to block DUV light reduces EUV light throughput.
Innovation Solution
Employing an EUV pellicle with high EUV transmittance and low DUV reflectivity to replace the DGL membrane, and using a pellicle DUV reflectivity mapping apparatus to assess its suitability by acquiring a two-dimensional DUV reflectivity map to ensure it meets a maximum reflectivity threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a dynamic gas lock (DGL) membrane is used to block DUV light, then image degradation is prevented, but EUV light throughput is reduced
Solution Approach 1:
The pellicle is designed with specific optical parameters - high transmittance for EUV light (wavelength 13.5nm) and low reflectivity for DUV light (wavelength 193-238nm). This selective parameter optimization allows the pellicle to differentiate between EUV and DUV light based on wavelength, achieving both DUV blocking and EUV transmission without the throughput penalty of a DGL membrane
Solution Approach 2:
The pellicle employs a composite structure consisting of a thin transparent support layer (such as quartz or silicon oxide) combined with a deposited coating layer (such as fluorinated materials or other low-DUV-reflectivity materials). This composite material approach enables simultaneous achievement of high EUV transmittance and low DUV reflectivity, resolving the contradiction between DUV blocking and EUV throughput
2Productivity
If an EUV pellicle is used to replace DGL membrane, then EUV light throughput is maintained, but DUV light blocking effectiveness must be verified
Solution Approach 1:
The patent replaces the mechanical DGL membrane system with an optical pellicle system that uses wavelength-selective optical properties rather than mechanical gas flow control. The pellicle's optical design (thin transparent support layer with specific coating) inherently provides DUV blocking while maintaining EUV throughput, and the mapping apparatus verifies this optical performance without mechanical intervention
Solution Approach 2:
The pellicle acts as an intermediary optical element positioned between the EUV light source and the photoresist. It mediates the interaction between light and photoresist by selectively transmitting EUV light while blocking DUV light through its engineered optical properties. The pellicle mapping apparatus serves as another intermediary tool to verify the pellicle's performance characteristics
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 EUV pellicle effectively blocks DUV light, preventing image degradation and maintaining EUV light throughput, thereby improving semiconductor device yield without the need for a DGL membrane.
Implementation Method 1
a DUV light source arranged to emit DUV light onto the pellicle to generate reflected light
Implementation Method 2
a DUV spectrophotometer arranged to measure an intensity of the reflected light
Implementation Method 3
a DUV spectrophotometer arranged to measure an intensity of the reflected light as a function of a wavelength or a photon energy
Data Source
AI summary
A two-dimensional deep ultraviolet (DUV) reflectivity map of an extreme ultraviolet (EUV) pellicle is acquired using a DUV reflectance measurement assembly having a DUV light source and a DUV spectrophotometer. A representation of the two-dimensional DUV reflectivity map may be displayed. Additionally or alternatively, it may be determined whether the EUV pellicle is usable for EUV lithography without a dynamic gas lock DUV light-reflective membrane by analyzing the two-dimensional DUV reflectivity map, and outputting an indication of the determination. In response to a determination that the EUV pellicle is usable, the EUV pellicle may be mounted on an EUV photolithography mask to form an EUV mask assembly and EUV photolithography performed using the EUV mask assembly to form a latent image of a pattern of EUV reflective and absorbing regions of the photomask on and/or in an EUV light-sensitive photoresist layer disposed on a surface of a semiconductor wafer.