Tarnishing of Mo/Si multilayer x-ray mirrors
1993; Optica Publishing Group; Volume: 32; Issue: 34 Linguagem: Inglês
10.1364/ao.32.006985
ISSN0003-6935
AutoresJ. H. Underwood, Eric M. Gullikson, Khanh B. Nguyen,
Tópico(s)Crystallography and Radiation Phenomena
ResumoMultilayer x-ray mirrors of molybdenum and silicon operating at normal incidence at energies just below the Si LII,III absorption edges are a key component in the development of soft-x-ray projection lithography. In this application high reflectivity is essential. Aging tests on such reflectors, with Mo as the last layer deposited, show that the structures decline in reflectivity with time when stored in air. Chemical analysis of a well-aged surface by photoelectron spectroscopy techniques reveals that the uppermost Mo layer eventually becomes completely oxidized to MoO3 and MoO2 and contaminated with carbonaceous materials. The oxidation can be prevented by storing the mirrors in an oxygen-free atmosphere or by depositing the silicon as the top layer. The reflectivity of tarnished mirrors can be restored by removing the oxides by argonion etching or wet chemical methods.
Referência(s)