The force of adhesion of 50 nm diameter diamond-like carbon sphere probes to three quartz substrates was measured using an atomic force microscope. The force of adhesion was measured prior to cleaning, within 10 minutes after cleaning, after storage in an N₂-purged cabinet, and after storage in an N2-purged vacuum oven. The evaluated cleaning recipes were SC1-like, SPM-like, and HF-based, each followed by ultra-pure deionized water (UPW) rinse and spin drying. The measurements were conducted in a Class 100 clean room at approximately 50% relative humidity. In addition, contact angle measurements were made on three additional quartz substrates using UPW before cleaning, after cleaning, and throughout N₂ storage. The adhesion force increased after cleaning as compared to the pre-cleaned state, continued to increase until reaching a maximum after 5 days of N₂ storage, and then decreased after 26 days for all three substrates. One substrate was then stored in a vacuum oven for 3 days, and the adhesion force decreased to 46% of the pre-cleaned state. The contact angle was reduced from over 30° before cleaning to 0° immediately after cleaning. During subsequent N₂ storage, the contact angle increased to 5° or greater after 18 hours for the substrate cleaned with the HF-based recipe and after 15 days for the substrates cleaned by the SC1-like and SPM-like recipes.

Date Published: 17 April 2014
PDF: 7 pages
Proc. SPIE 9048, Extreme Ultraviolet (EUV) Lithography V, 90480N (17 April 2014); doi: 10.1117/12.2048310

Published in SPIE Proceedings Vol. 9048:
Extreme Ultraviolet (EUV) Lithography V
Obert R. Wood II; Eric M. Panning, Editor(s)