Low-loss HR coatings on fused silica substrates for 193 nm micro-lithography applications

A novel scheme of homologous differential transmissivity and reflectivity measurer

“…The theoretical output voltage of the balanced detector is (4) However, even if the He-Ne laser is entirely blocked, the output voltage denoted as is non-zero and exhibits slow fluctuation over time, resulting from distinct dark currents of two photodiodes. Subsequently, the output voltage is expressed as (5) When the output voltage satisfies , NHDTRM is deemed to have attained the optical balanced state where . Based on (2), (3) and the condition of optical balance, the transmissivity of M to be measured is expressed as (6) The scale factor is independent of .…”

“…Optical coatings are extensively applied in optoelectronic systems, especially low-loss coatings, serving as critical components in laser gyroscopes [1] , high-power lasers [2] , gravitational wave detection [3,4] , lithography [5] , etc. The advancement of ultra-precision polishing technology and low-loss coating technology have made it possible to manufacture coated mirrors with loss ratio at ppm scale, such as high-reflectivity coated mirrors with reflectivity up to 99.99984% [6] .…”

MOCVD Fabrication of Magnesium Fluoride Films: Effects of Deposition Parameters on Structure and Morphology

“…The number of available materials in the UV range is limited because of the strong absorption of several materials. Commonly used coatings in this region include metal oxides (Al 2 O 3 , Sc 2 O 3 , HfO 2 , and SiO 2 ) [8][9][10] and wide band-gap fluorides (MgF 2 , YF 3 , LaF 3 , AlF 3 , LiF, and CeF 3 ). [2,[11][12][13] Among these magnesium difluoride (MgF 2 ) represents a satisfactory competitor as a UV transparent material.…”

High-Reflectance Coatings at 193nm

“…With the growth of applications for deep ultraviolet-vacuum ultraviolet (DUV-VUV) lasers in many areas and especially in semiconductor industry, there is an ever-growing demand for high quality optical components in these systems. At this time the shortest wavelength in semiconductor lithography mass production is 193nm [1], which is emitted by an excimer laser with ArF gas mixture. However, at this short wavelength region only few materials can be used for the coatings deposited on the components used in the beam lines of laser systems due to their high optical absorption.…”

“…Though having excellent mechanical stability, HR coatings with oxide pairs can hardly reach a high reflectance due to their relative high optical absorption and small contrast of refractive index. By contrast, HR coatings on the basis of fluoride pairs and combinations of oxide and fluoride pairs are promising designs for practical applications [1,4,5].…”