AVS 45th International Symposium
    Plasma Science and Technology Division Monday Sessions
       Session PS-MoP

Paper PS-MoP7
Increase of Etch Resistance of Deep UV Photoresist by Implantation

Monday, November 2, 1998, 5:30 pm, Room Hall A

Session: Plasma Science and Technology Poster Session
Presenter: K.K. Ong, Nanyang Technological University, Singapore
Authors: K.K. Ong, Nanyang Technological University, Singapore
C.P. Soo, National University of Singapore
M.H. Fan, Chartered Semiconductor Manufacturing Ltd., Singapore
A.J. Bourdillon, National University of Singapore
M.H. Liang, Nanyang Technological University, Singapore
L.H. Chan, Chartered Semiconductor Manufacturing Ltd, Singapore
Correspondent: Click to Email
As device dimension shrinks, there is a need to use deep UV lithography to define sub-quarter micron features. However, most of the novel photoresists used in deep UV lithography generally face a problem: low etch resistance. In this study, implantation of various kinds of dopant into the resist layer was the approach to increase etch resistance. The first approach was that implantation of dopant into the resist formed a carbonized layer at the surface. The carbonized layer formed at the surface could be clearly observed on the cross SEM micrographs. This might increase the etch resistance by the assumption that the etch resistance is proportional to the C/H ratio of the resist (made by Wilson et al.). The etch rate of the treated resist was extracted from detailed experiment. Generally for both B and P implantation, the carbonized layer was thicker with increase implantation voltage. The thickness could reach to the range of around 0.5 µm. This enables a thinner resist (probably at 0.6-0.7 µm) used in the lithography, which enhance the resolution and the depth of focus. Secondly, implantation of Si into the resist might form the silylated resist which normally bears a higher etch resistance. Besides that, implantation of B or P into the oxide substrate increased the oxide etch rate greatly with respect to the above resist layer. The greater difference in the etch rate of the resist and oxide substrate gave a better etch selectivity.