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Proceedings Paper

An ultrasensitive bio-surrogate for nanoporous filter membrane performance metrology directed towards contamination control in microlithography applications
Author(s): Farhan Ahmad; Barbara Mish; Jian Qiu; Amarnauth Singh; Rao Varanasi; Eilidh Bedford; Martin Smith
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Paper Abstract

Contamination tolerances in semiconductor manufacturing processes have changed dramatically in the past two decades, reaching below 20 nm according to the guidelines of the International Technology Roadmap for Semiconductors. The move to narrower line widths drives the need for innovative filtration technologies that can achieve higher particle/contaminant removal performance resulting in cleaner process fluids. Nanoporous filter membrane metrology tools that have been the workhorse over the past decade are also now reaching limits. For example, nanoparticle (NP) challenge testing is commonly applied for assessing particle retention performance of filter membranes. Factors such as high NP size dispersity, low NP detection sensitivity, and high NP particle-filter affinity impose challenges in characterizing the next generation of nanoporous filter membranes. We report a novel bio-surrogate, 5 nm DNA-dendrimer conjugate for evaluating particle retention performance of nanoporous filter membranes. A technique capable of single molecule detection is employed to detect sparse concentration of conjugate in filter permeate, providing >1000- fold higher detection sensitivity than any existing 5 nm-sized particle enumeration technique. This bio-surrogate also offers narrow size distribution, high stability and chemical tunability. This bio-surrogate can discriminate various sub-15 nm pore-rated nanoporous filter membranes based on their particle retention performance. Due to high bio-surrogate detection sensitivity, a lower challenge concentration of bio-surrogate (as compared to other NPs of this size) can be used for filter testing, providing a better representation of customer applications. This new method should provide better understanding of the next generation filter membranes for removing defect-causing contaminants from lithography processes.

Paper Details

Date Published: 8 March 2016
PDF: 7 pages
Proc. SPIE 9778, Metrology, Inspection, and Process Control for Microlithography XXX, 97783C (8 March 2016); doi: 10.1117/12.2219315
Show Author Affiliations
Farhan Ahmad, Pall Corp. (United States)
Barbara Mish, Pall Corp. (United States)
Jian Qiu, Pall Corp. (United States)
Amarnauth Singh, Pall Corp. (United States)
Rao Varanasi, Pall Corp. (United States)
Eilidh Bedford, Pall Corp. (United States)
Martin Smith, Pall Corp. (United States)

Published in SPIE Proceedings Vol. 9778:
Metrology, Inspection, and Process Control for Microlithography XXX
Martha I. Sanchez, Editor(s)

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