IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Engineering Tuesday Sessions
       Session SE-TuM

Paper SE-TuM6
Low Temperature Remote Plasma Cleaning of the Fluorocarbon and Polymerized Residues formed during Contact Hole Dry Etching

Tuesday, October 30, 2001, 10:00 am, Room 132

Session: Surface Engineering II: Cleaning, Modification, and Finishing
Presenter: H. Seo, Hanyang University, Korea
Authors: H. Seo, Hanyang University, Korea
H. Soh, Hanyang University, Korea
Y. Kim, Hanyang University, Korea
Y.C. Kim, Hanyang University, Korea
H. Jeon, Hanyang University, Korea
Correspondent: Click to Email
Reducing contact hole resistance in ultra large scale integration becomes very important as the contact hole size getting small.@footnote 1@ Reactive ion etching (RIE) using fluorocarbon is widely used to open contact holes due to its high anisotropic and selective silicon etching characteristics. However, the RIE process induces fluorocarbon residues and results in high contact resistance and defects at the metal-silicon interface. Furthermore, these residues polymerized after photo resist (PR) ashing process. These polymerized residues were reported to be non-volatile, and chemically and thermally stable.@footnote 2@ Therefore, these polymer residues must be removed prior to metal contact. In this study, we investigated the low temperature oxygen and hydrogen remote plasma cleaning of the polymer residues formed at the contact hole during RIE and PR ashing processes. Samples having shallow trench isolation structure were prepared by RIE using CHF@sub 3@/CF@sub 4@ gas. The efficiency of cleaning was systematically evaluated at various conditions such as plasma power, exposure time, gas flow rate and sample temperature. Polymer residues before and after cleaning were analyzed using in-situ Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM) systems. Also, the polymer residues were directly observed before and after cleaning using scanning electron microscope (SEM). Carbon and fluorine impurities were significantly reduced below detection limit of AES after remote plasma cleaning. Also, the C-C/C-H and C-F@sub x@ (x=1,2,3) types bonding were not observed by XPS. This paper presents the efficiency of the remote plasma cleaning of the polymerized residues formed during RIE and ashing processes at the contact hole. @FootnoteText@ @footnote 1@K. Sakuma, K. Machida, K. Kamoshida, Y. Sato, K. Imai and E. Arai, J. Vac. Sci. Technol. B 13(3), May/June (1995) @footnote 2@J. Fonash, J. Electrochem. Soc. 137, 3885 (1990)