Laser Ablation/Ionization Characterization of Solids
EMSL Project ID
1365a
Abstract
Deep UV optical materials are required by the semiconductor industry. These generally crystalline and amorphous materials must be resistant to laser-induced damage from high power nanosecond excimer lasers. Laser damage occurs when light is absorbed, creating defects in the crystal lattice. These defects can lead to the emission of atoms, ions and molecules from the sample. One specific field where laser damage is of serious concern is semiconductor lithography, which now uses excimer laser pulses at 157 nm. CaF2 is a candidate material for use in this new generation of lithography. In order to prevent unnecessary damage of optical components, it is necessary to understand the mechanisms for laser damage and the factors that serve to enhance it. We propose to study various aspects of laser interactions with CaF2, including impurity absorbance and various forms of damage caused by incident UV laser light. Laser light at 266 nm of femtosecond (fs) and nanosecond (ns) rduration is used to induce ion and neutral particle emission from cleaved samples of CaF2. The resulting mass spectra show significant differences suggesting that different mechanisms for desorption take place at each of these pulse rates. We will study irradiation of CaF2 by ns and fs pulses at 266 nm and measure the transmission and reflection of fs laser pulses at 266 nm, the results of which will reveal a non-linear absorption process in effect at high incident intensities. In addition, the kinetic energy profiles of desorbed Ca and K contaminant atoms will be measured. We will explore the effects of impurities in desorption of atoms from CaF2 using fs and ns pulses.
Project Details
Project type
Exploratory Research
Start Date
2003-09-03
End Date
2006-08-08
Status
Closed
Released Data Link
Team
Principal Investigator