Laser Conditioning Process Research Articles

Effect of Laser Conditioning on Surface Modification and Laser Damage Resistance of SiO2 Antireflection Film

SiO2 sol-gel antireflection film coated on fused silica can reduce the reflection loss and improve the transmittance of the optical component, although it is still prone to laser induced damage. Laser conditioning is an effective way to improve the laser induced damage threshold (LIDT) of SiO2 sol-gel antireflection film. In this paper, single-layer SiO2 sol-gel antireflection films pretreated by triple-frequency laser with different parameters are characterized by the macroscopical parameters, such as transmittance, refractive index, and thickness. The law of surface modification and the defect removal mechanism of the SiO2 sol-gel antireflection film by laser conditioning are obtained. It is found that laser conditioning can reduce the thickness of the film and introduce densification. In addition, laser conditioning can eliminate micro-defects, such as vacancies and voids in the preparation of SiO2 sol-gel antireflection films, which is the main reason to improve the laser damage resistance of films. Finally, the laser conditioning process with three step laser energy combinations of (0.2–0.6–1.0) Fth0 (zero damage threshold) is the best one to obtain high transmittance, and excellent effects on structure modification and defect removal of films. The research in this paper provides data support for the engineering application and mechanism research of laser conditioning.

Laser-assisted spalling of large-area semiconductor and solid state substrates

Abstract

Laser Assisted SiC Wafering Using COLD SPLIT

Kerf-free wafering techniques hold the potential to drastically reduce material losses in semiconductor manufacturing processes. Spalling processes use externally applied stresses to separate crystalline materials along crystal planes with well-defined thickness. Spalled substrates, however, exhibit striations from crack propagation along the crystal, a pattern called Wallner lines. Here, we demonstrate a wafering process that scales favorably for SiC substrates starting from 1 inch in diameter. To eliminate the Wallner line pattern, we use a laser-conditioning process with high numerical aperture at photon energies below the material bandgap energy, using multi-photon effects. The process leads to SiC surfaces with a roughness after spalling of Ra< 4μm.

激光预处理提升DKDP晶体加工表面的抗损伤能力

激光预处理提升DKDP晶体加工表面的抗损伤能力

The application of laser-induced damage spot size effect for laser conditioning mechanism

We propose the spot-size effect in laser-induced damage to optical thin films as a method to investigate the defect removal model which is one of the laser conditioning mechanisms, and the theoretical and experimental studies are presented. A standard deviation σ 2 is set up for fitting the damage thresholds which are obtained by multi-spot size test. The laser conditioning effect on ZrO 2 /SiO 2 multilayer high reflective films is analyzed through this application. It is found that the mean distance of two initiating defects is increased by laser conditioning, which means that the defect density is decreased. Thus, the initiating defects are removed partially by laser conditioning. Furthermore, the intrinsic damage threshold of the film is little affected through the laser conditioning process.

激光预处理中缺陷上的激光能量覆盖

激光预处理中缺陷上的激光能量覆盖

Laser conditioning on HfO_2 film monitored by calorimeter

Conditioning effect on HfO2 single-layer film by quasi-cw laser was investigated. The conditioning process was monitored with laser calorimeter. Experimental results revealed that the HfO2 film absorption decreased as a function of the irradiation dose. Higher laser power accelerated the conditioning process. The conditioning effect could not be explained by water annihilation. AFM pictures of the film surface showed that the structural information in the conditioned region was different from the unconditioned region. Monitoring the in situ absorption, laser calorimeter is a promising tool to investigate the laser conditioning process.

SOCRATE: an optical bench dedicated to the understanding and improvement of a laser conditioning process

We present an automatic excimer laser bench (SOCRATE) allowing for the treatment of optical components by laser conditioning. This apparatus, developed at the Commissariat a l'Energie Atomique-Le Ripault, has been designed to add to this conditioning process an in situ, accurate laser-induced damage threshold (LIDT) measurement and different nondestructive optical techniques for the characterization of the component during treatment. Through different examples, we demonstrate the importance of these characterizations to improve the understanding of the laser conditioning. The role of an in situ adapted metrology associated in real time with a laser conditioning bench offers new opportunities to analyze laser-induced damage mechanisms and subsequently to increase the LIDT of optical components.