Microfabrication of thick tungsten films for use as absorbers of deep X-ray lithography masks |
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Authors: | H. Okuyama Y. Hirata H. Takada |
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Affiliation: | (1) Harima Research Laboratories, Sumitomo Electric Industries, Ltd., 1431-12 Harima Science Garden City, Kamigori, Hyogo 678-1205, Japan E-mail: okuyama-hiroshi@sei.co.jp, JP |
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Abstract: | We fabricated thick (5 μm) tungsten (W) film patterns by sputtering and dry etching, and realized a new deep X-ray lithography mask. The X-ray mask with 5-μm-thick W absorbers could expose about 1-mm-thick resist structures. In the deposition process of W films, the column structure of about 0.2 μm grain size, from which pattern edge roughness originates, disappeared by adding nitrogen into the sputtering gas. W film etching was carried out by reducing gas pressure and cooling the substrate (−40 °C), and a side etch width of below 0.2 μm was obtained. From the results of the pattern edge roughness and the side etch width, a pattern fabrication accuracy below ±0.5 μm was achieved. Furthermore, film stress, which induces pattern distortion, was reduced to below 50 MPa by controlling the sputtering gas pressure. The obtained mask achieved a pattern distortion below ±0.3 μm. Received: 7 July 1999/Accepted: 29 May 2000 |
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