Suppression of surface crystallization on borosilicate glass using RF plasma treatment

• Published in: Applied surface science Vol. 316; pp. 484 - 490
• Main Authors: Yoo, Sunghyun, Ji, Chang-Hyeon, Jin, Joo-Young, Kim, Yong-Kweon
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.10.2014; Elsevier
• Subjects: Borosilicate glass; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Micro-optical device; Physics; Plasma treatment; Surface crystallization; Micro-optical device; Plasma treatment; Borosilicate glass; Surface crystallization; Crystallization; Plasma assisted processing
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2014.07.083

•We have prevented surface crystallization on Borofloat wafer during heat treatment.•Over 99% of the cristobalite nucleation has been suppressed by plasma pretreatment.•Fundamentals of the nucleation mechanism have been examined.•Average surface roughness has been enhanced by a factor of 15.•Optical transparency has been enhanced by a factor of 3. Surface crystallization on a commercial grade borosilicate glass wafer, Borofloat® 33, is effectively prevented against 3h of thermal reflow process at 850°C. Surface plasma treatment with three different reactive gases, CF4, SF6, and Cl2, has been performed prior to the annealing. The effect of plasma treatment on surface ion concentration and nucleation of cristobalite were examined through optical microscope and x-ray photoemission spectroscopy. The dominant cause that suppresses crystallization was verified to be the increase of surface ion concentration of alumina during the plasma treatment. Both CF4 and SF6 treatment of no less than 30s showed significant efficacy in suppressing crystallization by a factor of more than 112. Average surface roughness and the optical transparency were also enhanced by a factor of 15 and 3, respectively, compared to untreated sample.