The materials of x-ray absorbers for x-ray mask have been changed from gold (Au) and tungsten-based alloys to tantalum (Ta) and Ta-based compounds in x-ray lithography (XRL). Different candidates of x-ray absorber, especially Ta-based (TaX) compounds, were sputtered and evaluated in this study. By incorporating silicon or germanium into tantalum, amorphous TaSi-based and TaGe-based compounds were formed and qualified as the absorber materials. Because the reproducibility of as-deposited stress by tuning the sputtering parameters is not so well for these compounds right after sputtering, we utilized the step annealing by RTA to control the stress such that within ±20 MPa is obtainable. Furthermore, with N2 plasma treatment in PECVD chamber the slope of stress with respect to annealing temperature is smaller and posses good stability after long-time exposure to the air. Finally, the etching properties of TaX compounds were compared with and without tri-layer structure of oxide/absorber/oxide. And, 0.35 μm patterns are etched successfully with vertical sidewall by Cl2 etchant.
|Number of pages||4|
|Journal||Proceedings of SPIE - The International Society for Optical Engineering|
|State||Published - 1 Jan 1999|
|Event||Proceedings of the 1999 Emerging Lithographic Technologies III - Santa Clara, CA, USA|
Duration: 15 Mar 1999 → 17 Mar 1999