Induced thermal stress fields for three-dimensional distortion control of Si wafer topography
| Autor: | Charles D. Schaper, Been-Der Chen, R. Fabian W. Pease |
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| Rok vydání: | 2004 |
| Předmět: | |
| Zdroj: | Review of Scientific Instruments. 75:1997-2002 |
| ISSN: | 1089-7623 0034-6748 |
| DOI: | 10.1063/1.1753101 |
| Popis: | Localized, controlled heating can induce a thermal stress field in silicon wafers and displace the surface topography in three dimensions, which is useful for nanoscale regulation of overlay in microcontact printing systems. Simulation and experimental results are presented to demonstrate the use of a thermal array consisting of a dense distribution of independent heating elements to locally displace silicon wafer alignment microstructures. An experimental apparatus comprised of a 7×7 array of thermal cycling sources is used to control the absolute three-dimensional position of surface microstructures. The system is used to demonstrate out-of-plane sensitivity of 1.4 μm/°C by thermomechanical displacement contributions from thermal expansion of the heating element. Rolloff in out-of-plane displacement of 200 nm/mm/°C in silicon at the boundary between heated and nonheated regions in this apparatus is exhibited. Dynamic real-time control of the substrate flatness is thus feasible and is demonstrated with the apparatus using feedback from three alignment microscopes, to sub-100 nm levels of regulation. Control of the in-plane microstructure position is achieved by stabilizing the vertical displacement with a mechanical nanopositioning stage, while establishing a thermal stress field to produce displacement sensitivity of 70 nm/°C. Real-time feedback control of the in-plane microstructure position is demonstrated, also within sub-100 nm of the target regulation level. |
| Databáze: | OpenAIRE |
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