EUV Mask Black Border Defect Control
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Solution Overview
Problem
EUV and DUV light reflection from black border regions in semiconductor wafer exposure leads to defects and critical dimension reduction in EUV lithography, where conventional masks are ineffective due to the short wavelength of EUV light.
Innovation Solution
An EUV mask design featuring a quartz substrate with a black border region, a multi-layered reflection film of alternately deposited molybdenum and silicon, an absorption layer including chromium or tantalum nitride, and blind layers of nitride films to minimize light reflection, specifically designed to absorb EUV and DUV light in the black border areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional transmission mask is used in EUV exposure, then the mask structure is simple, but the mask cannot effectively control EUV light reflection from black border regions causing defects
Solution Approach 1:
The mask structure is segmented into multiple functional layers: a quartz substrate, a multi-layered reflection control film (alternating Mo and Si layers), an absorption layer (Cr, CrN, TaBN, or TaN), and blind layers (SiON, TaBON, or CrON). Each layer serves a specific function in controlling EUV and DUV light interaction, with the multi-layered reflection control film providing precise optical path management to prevent defects from black border region reflections.
Solution Approach 2:
The mask employs composite material structures combining different optical properties: the multi-layered reflection control film uses alternating molybdenum and silicon layers to control EUV reflectivity, while the absorption layer uses materials like chromium nitride or tantalum boron nitride to absorb DUV light. The blind layers use nitride-based composite materials to provide additional reflection control, creating a composite mask structure that simultaneously addresses both EUV and DUV light management.
2Object-affected harmful factors
If the multi-layered reflection film covers the entire black border region, then light reflection is minimized, but manufacturing complexity and cost increase
Solution Approach 1:
The multi-layered reflection control film is selectively applied only to specific regions of the black border area where reflection control is most critical, rather than uniformly covering the entire black border region. The absorption layer and blind layers are strategically positioned to target specific reflection paths. This localized approach provides effective reflection control at the critical interfaces while reducing material usage and manufacturing complexity compared to full-coverage solutions.
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 mask effectively reduces defects and critical dimension variations by minimizing EUV and DUV reflection, maintaining EUV reflectivity at 0.018% or less and preventing pattern defects, thus enhancing the precision of semiconductor fabrication.
Implementation Method 1
a multi-layered reflection film formed over the quartz substrate so that a portion of the black border region is exposed
Implementation Method 2
The multi-layered reflection film is formed by alternately depositing at least 40 molybdenum (Mo) films and at least 40 silicon (Si) films
Implementation Method 3
an absorption layer formed over the multi-layered reflection film
Implementation Method 4
a first blind layer formed over the absorption layer
Data Source
AI summary
An extreme ultra violet (EUV) mask is disclosed, which prevents defects from shot overlap encountered in wafer exposure as well as reflection of unnecessary EUV and DUV generated in a black border region, such that a pattern CD is reduced and defects are not created. The EUV mask includes a quartz substrate, a multi-layered reflection film formed over the quartz substrate to reflect exposure light, an absorption layer formed over the multi-layered reflection film, a black border region formed over the quartz substrate that does not include the multi-layered reflection film, and a blind layer formed in a position including at least one of over the absorption layer, over the quartz substrate, and below the quartz substrate.