EUV Mask Multilayer Deposition for Phase Defect Control
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Solution Overview
Problem
Existing EUV lithography masks suffer from microscopic defects in the substrate and reflective multilayer coating, leading to phase errors that negatively impact lithography processes, as these defects are difficult to inspect and repair.
Innovation Solution
A method involving tilting and rotating the substrate during the deposition of the reflective multilayer coating to laterally displace deformations, thereby reducing the accumulated phase shift error and minimizing the impact of phase defects on light reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reflective multilayer coating is deposited on a substrate to create an EUV mask, then the mask achieves the required reflective properties for lithography, but microscopic defects in the substrate cause deformations in the coating layers that affect pattern printability
Solution Approach 1:
The substrate is tilted at a specific angle (greater than 0 degrees and less than 90 degrees) during the deposition process to proactively displace deformations before they can accumulate and affect mask performance. This preliminary geometric adjustment prevents the harmful effect of defect-induced deformations rather than correcting them after occurrence.
Solution Approach 2:
The deposition process parameters, specifically the substrate tilt angle, are changed from the conventional perpendicular orientation to an inclined orientation. This parameter change transforms the deposition geometry such that deformations are laterally displaced across multiple layers, reducing their cumulative impact on mask printability.
2Manufacturing precision
If the substrate is tilted and rotated during deposition to displace deformations, then accumulated phase shift error is reduced, but the deposition process becomes more complex
Solution Approach 1:
The substrate is rotated about an axis parallel to the landing direction of particles during the deposition process. This dynamic rotation, combined with the tilt, creates a complex motion that systematically displaces deformations across multiple layers. The rotation transforms the deformation pattern from a static vertical alignment to a distributed lateral pattern, reducing phase shift error accumulation.
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 laterally displaced phase defect region reduces phase shift errors, enhancing imaging fidelity and increasing the allowable size of defects in masks, thus improving manufacturing yield.
Implementation Method 1
a reflective multilayer coating (multilayer mirror) deposited on a substrate
Implementation Method 2
Any defects, including microscopic defects, in the substrate causes deformations in material layers of the reflective multilayer coating
Data Source
AI summary
A mask, method of fabricating same, and method of using same are disclosed. In an example, a mask includes a substrate and a reflective multilayer coating deposited over the substrate. The reflective multilayer coating is formed by positioning the substrate such that an angle α is formed between a normal line of the substrate and particles landing on the substrate and rotating the substrate about an axis that is parallel with a landing direction of the particles. In an example, reflective multilayer coating includes a first layer and a second layer deposited over the first layer. A phase defect region of the reflective multilayer coating includes a first deformation in the first layer at a first location, and a second deformation in the second layer at a second location, the second location laterally displaced from the first location.