Title
Increased particle inspection sensitivity by reduction of background scatter variance
Author
van der Walle, P.
Kumar, P.
Ityaksov, D.
Versluis, R.
Maas, D.J.
Kievit, O.
Janssen, O.
van der Donck, J.C.J.
Publication year
2013
Abstract
In dark-field particle inspection, the limiting factor for sensitivity is the amount of background scatter due to substrate roughness. This scatter forms a speckle pattern and shows an intensity distribution with a long tail. To reduce false-positives to an acceptable level, a high detection threshold should be chosen such that the tail of the background distribution is avoided. We have modeled an optimized illumination mode, that reduces the variance in the background distribution. This illumination mode illuminates the substrate from multiple azimuth angles. We show that the speckle patterns generated by each azimuth angle can be independent from each other. Therefore by combining the angles, the variance of the background signal is reduced. We show that for the parameters of our inspection system the detection threshold can be reduced by a factor three, resulting in a lower detection limit that is 20% smaller in particle size. The change in the background scattering distribution was confirmed by experiments. © 2013 SPIE.
Subject
Physics & Electronics
NI - Nano Instrumentation
TS - Technical Sciences
High Tech Systems & Materials
Electronics
Industrial Innovation
Dark-field microscopy
Detection limit
EUVL
Illumination
Particle inspection
Qualification
Rapid Nano
Speckle
To reference this document use:
http://resolver.tudelft.nl/uuid:9bb28268-fd80-4db6-b965-e2540f5e636e
TNO identifier
473181
ISBN
9780819494634
ISSN
0277-786X
Source
27th Conference on Metrology, Inspection, and Process Control for Microlithography, 25-28 February 2013, San Jose, CA, USA, 8681
Series
Proceedings of SPIE - The International Society for Optical Engineering
Article number
868116
Document type
conference paper