|
Surface damage and surface contamination of optics has long been a source of problems for laser,
lithography and other industries. Nano-sized surface defects may present significant performance
issues in optical materials for deep UV and EUV applications. The effects of nanometer sized
surface damage (scratches, pits, and organics) on the surface of optics made of traditional materials
and new more exotic materials is a limiting factor to high end performance. Angstrom level
smoothing of materials such as calcium fluoride, spinel, zinc sulfide, BK7 and others presents a
unique set of challenges. Exogenesis Corporation, using its proprietary Accelerated Neutral Atom
Beam (ANAB) technology, is able to remove nano-scale surface damage and contamination and
leaves many material surfaces with roughness typically around one angstrom. This process
technology has been demonstrated on nonlinear crystals, and various other high-end optical
materials. This paper describes the ANAB technology and summarizes smoothing results for
various materials that have been processed with ANAB. All surface measurement data for the paper
was produced via AFM analysis.
Exogenesis Corporation’s ANAB processing technology is a new and unique surface modification
technique that has demonstrated to be highly effective at correcting nano-scale surface defects.
ANAB is a non-contact vacuum process comprised of an intense beam of accelerated, electrically
neutral gas atoms with average energies of a few tens of electron volts. The ANAB process does not
apply normal forces associated with traditional polishing techniques. ANAB efficiently removes
surface contaminants, nano-scale scratches, bumps and other asperities under low energy physical
sputtering conditions as the removal action proceeds. ANAB may be used to remove a precisely
controlled, uniform thickness of material without any increase of surface roughness, regardless of
the total amount of material removed. The ANAB process does not involve the use of slurries or
other polishing compounds and therefore does not require any post process cleaning. ANAB can be
integrated as an in-situ surface preparation method for other process steps in the uninterrupted
fabrication of optical devices.
|
