Lloyd's Interference Lithography System Employing Beam Shaping Technique for Wafer-scale Nano-patterning
| Autor: | Han-jung Chang, 張漢榮 |
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| Rok vydání: | 2016 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 104 Laser interference lithography (LIL) has been an effective and inexpensive approach for generating submicron periodic patterns in one-dimension or two-dimension over a large area with high throughput. Among various configurations, a Lloyd-mirror configuration has been used for a wide range of applications due to its simplicity in system setup and the control of pattern periodicity. However, inherent Gaussian distribution of the laser beam leads to a non-uniform grating pattern formation, especially for wafer-scale patterning using a single-beam Lloyd''s mirror interferometer. In this thesis, a refractive beam shaper is utilized in a Lloyd''s mirror interferometer to achieve wafer-scale patterning of periodic structures with a uniform resultant profile. The entire system setup is similar to Lloyd’s mirror interferometer but additional refractive beam shaper and tunable beam expander are needed for converting the Gaussian beam into a flat-top one. With the help of a uniform light field, the entire system can be more compact and is less sensitive to the environmental condition. We successfully demonstrated uniform grating structures over 2-inch wafers with a fill factor variation of less than ±0.55%. As-realized two-dimensional square and hexagonal grating structures also reveal almost constant fill factor (FF = ±1.25%) and circular geometry (e = ±0.04). Even higher rotational-symmetry structures can be uniformly realized. We believe that the proposed system will be very useful for industrial applications, especially for uniform gratings formation during distributed feedback laser fabrication. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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