Effect of rotationally moving surface on roughness measurement of sputtered Pt film with close-loop correction using adaptive optics
| Autor: | Chia He Wang, Pin Wen Chen, Yiin Kuen Fuh, Zheng Hong Lai, Chieh Tse Huang |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Materials science
business.industry 020206 networking & telecommunications Rotational speed 02 engineering and technology Surface finish Laser 01 natural sciences Atomic and Molecular Physics and Optics Electronic Optical and Magnetic Materials law.invention 010309 optics Speckle pattern Optics law 0103 physical sciences 0202 electrical engineering electronic engineering information engineering Surface roughness Electrical and Electronic Engineering Thin film Stylus business Adaptive optics |
| Zdroj: | Optik. 127:1349-1353 |
| ISSN: | 0030-4026 |
| DOI: | 10.1016/j.ijleo.2015.10.056 |
| Popis: | An optical technique which allows the roughness measurement of sputtered thin film on silicon surface under high rotational speed up to 1500 rpm was developed. The rotationally moving effect hinders most in situ optical inspection methods due to the induced disturbance and image aberration, particularly in the circumferential region where the speed reaches the maximum. We present an in situ measurement of surface roughness that is combining on adaptive optics (AO) and binarized analysis of speckle pattern images. The aim of this study was to demonstrate the necessity for AO compensation in regions of moving surfaces under rotating speeds at 750 rpm and 1500 rpm, respectively. A speckle image was obtained by projecting a laser beam onto the wafer surface, and the laser pattern image reflected from the surface was binarized to experimentally correlate the bright/dark ratio with the surface roughness. The proposed AO-assisted system is in good agreement with the still condition and less than 3.05% error values can be consistently obtained. Furthermore, the proposed system can be used as an in situ roughness measurement on rotating surfaces. Measurement results of five sputtered Pt-film wafers having roughness ranging from 26 to 73 nm demonstrate an excellent correlation between the intensity distribution of binarized images and average roughness. Two trend equations can be obtained as Y1 = 0.2605x−0.997 and Y2 = 0.1961x−0.905, respectively, for predicting the moving surface roughness of Pt thin film at different moving speeds with repeatable accuracy. The reliability of the AO-integrated technique in obtaining roughness data of surfaces under various speed conditions (from 1.18 to 6.28 m/s) was validated and found to be in good agreement with traditional stylus technique. |
| Databáze: | OpenAIRE |
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