標題: Evaluating the impact of spherical aberration on sub-0.2-micron contact/via hole patterning
作者: Chou, SY
Lou, JC
Lai, CM
Liang, FJ
Chen, LJ
電子工程學系及電子研究所
Department of Electronics Engineering and Institute of Electronics
關鍵字: contact hole;depth of focus;attenuated PSM;OAL spherical aberration;best focus shift;quadrupole illumination
公開日期: 2001
摘要: Several super resolution techniques, such as phase-shifting mask (PSM) and off-axis illumination (OAI), have been reported to extend the resolution limit and increase the depth-of-focus ( DOF) of optical lithography. However, these techniques provide less immunity to spherical aberration than the conventional approaches like chrome binary mask and low coherent illumination. Best focus position shift is the most well known anomalous phenomenon resulted from spherical aberration. In this paper, the origin of best focus shift is explained in pictorial and analytical forms. The phenomenon is evaluated by observing the exposure-defocus windows of sub-0.2mum hole patterns from an 18 % transmission rim-type attenuated PSM combined with several types of illumination. Under high coherent illumination, severe focus shift was observed in sparse patterns as strong phase-shifting effect is applied. For dense hole patterns,, OAI results in abrupt focus position variation at specific pattern pitch. The experimental results show that spherical aberration would induce best focus shift, distortion of process windows, loss of DOF, and shrink-age of iso/dense process window overlap. Two approaches were proposed to suppress the impact of spherical aberration. One is introducing proper amount of phase bias in attenuated PSM to adjust the wave aberration in the lens. The other more feasible method is using a customized illumination. A synthesized illumination aperture was proposed to compensate the focus shift. Excellent lithographic performance was obtained in the experiment from this method.
URI: http://hdl.handle.net/11536/19008
http://dx.doi.org/10.1117/12.435668
ISBN: 0-8194-4032-9
ISSN: 0277-786X
DOI: 10.1117/12.435668
期刊: OPTICAL MICROLITHOGRAPHY XIV, PTS 1 AND 2
Volume: 4346
起始頁: 1318
結束頁: 1327
顯示於類別:會議論文


文件中的檔案:

  1. 000175014100134.pdf