AVS 53rd International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS2-TuP

Paper PS2-TuP11
The Behavior of Polymer Film Deposition during Etching the Oval Contact Holes

Tuesday, November 14, 2006, 6:00 pm, Room 3rd Floor Lobby

Session: Etching and Process Integration Poster Session
Presenter: S.-I. Cho, Samsung Electronics Co. LTD, South Korea
Authors: S.-I. Cho, Samsung Electronics Co. LTD, South Korea
S. Lim, Samsung Electronics Co. LTD, Korea
H. Baik, Samsung Advanced Institute of Technology, Korea
Y. Lee, Samsung Electronics Co. LTD, Korea
C.-J. Kang, Samsung Electronics Co. LTD, Korea
H. Cho, Samsung Electronics Co. LTD, Korea
J.-T. Moon, Samsung Electronics Co. LTD, Korea
Correspondent: Click to Email
Recently, the distorted pattern transfer during the high aspect ratio contact etching process has been reported. The reason of the deformation seems to be the result of non-uniform polymer deposition and/or the deflection of ion trajectory. This study is intended to clarify the behavior of the polymer deposition and its effect on the pattern deformation. The thickness of the polymer films on the sidewall of oval holes after etching was measured by cross-sectional TEM and SEM. The samples with carbonic masking layer were prepared after etching with C4F6, Ar, and O2 chemistry. The aspect ratio of the holes was 15. The thickness of the deposited film is variable with respect to the shape and the position of the holes. A thicker film is deposited along the sidewall of the shorter axis of the oval pattern than the sidewall of the longer axis at the middle of the holes. However, a thinner film is deposited along the sidewall of the shorter axis at the opening of the holes. This difference of film thickness can be explained by the behavior of sputtered masking materials and the randomly moved polymer radicals. The differently deposited films on the sidewall of the holes result in the deformation of the transferred pattern. Different film thickness at the opening produces the asymmetric local electrical field. The electric field results in bending the ion trajectory to the longer axis. Because of the ion accumulation, the profile in the longer open axis becomes more vertical. Moreover, the thicker film on the sidewall of shorter axis at the middle of the holes prevents from etching the sidewall. Therefore, transferred patterns in the bottom of the holes become more oval shaped than patterns in the masking layer.