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Title (journal) Data Rec., Storage & Processing. — 2005. — Vol. 7, N 1.
Pages 3-16
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Title (article) Modeling of information recording and selective etching processes in inorganic resists
Authors A. N. Morozovska, S. A. Kostyukevych
Kiev, Ukraine
Annotation Theoretical consideration and computer modeling of information pit record-ing and etching processes in chalcogenide vitreous semiconductors are pro-posed, namely we demonstrate how to record and develop information pits with the necessary shape and sizes in the inorganic resist using focused Gaussian laser beam and selective etching. It has been shown that photo-transformed region cross-section could be almost trapezoidal or parabolic depending on the resist material optical absorption, recording beam power, exposure, etchant selectivity and etching time. Namely, during the laser il-lumination and thermal heating caused by it, photosensitive material is the quasi-equilibrium microscopic mixture of the transformed and non-transformed phases with different optical absorption coefficients: temperature dependent near the absorption edge «transformed» coefficient and almost independent coefficient . If after thermal heating, the photo-transformed region «bleaches» and the pit depth increases more rapidly under the following laser power increasing. If , the photo-transformed region «darkens» and the pit depth increases sub-linearly or even saturates under the following laser power increasing. Thus, almost parabolic or flattened pits appear when , whereas the pits with elongated tops appear when . After illumination, the spatial distribution of photo-transformed material fraction was calculated using the Kolmogorov-Awrami equation. Analyzing obtained results, we derived a rather simple approximate analytical expression for the dependence of the photo-transformed region width and depth on the recording Gaussian beam power, radius and exposure time. Then the selective etching process was simulated numerically. The obtained results quantitatively describe the cha-racteristics of pits recorded by the Gaussian laser beam in thin layers of As40S60 chalcogenide semiconductor. Our model open possibilities how to
Key words information pits, optical disks, inorganic resist, selective etching.
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