Substrate recovery of Mo-Si multilayer coated optics
Imaging optics in a soft x-ray projection lithography (SXPL) system must meet stringent requirements to achieve high throughput and diffraction limited performance. Errors in the surface figure must be kept to less than {approximately}1 nm and the rms surface roughness must be less than 0.1 nm. The ML coatings must provide high reflectivity (> 60%) at wavelengths in the vicinity of 13 nm. The reflectivity bandpasses of the optics must be aligned within 0.05 nm. Each coating must be uniform across the surface of the optic to within 0.5%. These specifications challenge the limits of the current capabilities in optics fabrication and ML deposition. Consequently a set of qualified SXPL imaging optics is expected to be expensive, costing in the range of 100--250 k$. If the lifetime of the imaging optics is short, the replacement cost could significantly impact the economic competitiveness of the technology. The most likely failure modes for the imaging optics are mechanisms that degrade the ML coatings, but which leave the substrates intact. A potentially low cost solution for salvaging the imaging optics could be to strip the damaged ML coating to recover the substrate and then deposit a new coating. In this paper the authors report on the use of reactive ion etching (RIE) to remove Mo-Si ML coatings from precision optical substrates. The goal of this work was to characterize the etching process both in the ML film and at the substrate, and to determine the effects of the etching on the surface figure and finish of the substrate.
- Research Organization:
- Lawrence Livermore National Lab., CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 10183306
- Report Number(s):
- UCRL-JC-114087; CONF-9305159-7; ON: DE93019610; TRN: AHC29312%%21
- Resource Relation:
- Conference: Optical Society of America (OSA) topical meeting on soft x-ray projection lithography,Monterey, CA (United States),10-12 May 1993; Other Information: PBD: Jun 1993
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
OPTICAL SYSTEMS
REFLECTIVE COATINGS
REMOVAL
OPTICAL EQUIPMENT
MATERIALS RECOVERY
MASKING
MICROELECTRONIC CIRCUITS
MOLYBDENUM
SILICON
ETCHING
COMPOSITE MATERIALS
LAYERS
426000
320303
COMPONENTS
ELECTRON DEVICES AND CIRCUITS
EQUIPMENT AND PROCESSES