AVS 47th International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS2-WeA

Paper PS2-WeA8
Process Characterization for Tapered Contact Etch

Wednesday, October 4, 2000, 4:20 pm, Room 311

Session: Feature Evolution
Presenter: H. Sakima, Tokyo Electron America
Authors: F.G. Celii, Texas Instruments, Inc.
Q. He, Texas Instruments, Inc.
J. DeBord, Texas Instruments, Inc.
H. Sakima, Tokyo Electron America
Correspondent: Click to Email
The demands placed on lithography by the constant reduction in feature size can sometimes be alleviated in conjunction with the etch process. For line patterning, photoresist trimming gives a large etch bias and reduces linewidths well-below the lithography limit. For hole patterning, a tapered etch profile results in a bottom hole diameter which can be significantly smaller than the patterned CD. We report the characterization of contact etch processes which give variable sidewall taper angles. Patterning at 248 nm gave contact holes at ~0.19 µm diameter in photoresist over organic BARC. The contact stack (BARC/oxide/SiN, 6 - 10 kÅ total stack thickness) was etched in a medium-density TEL Dipole Ring Magnetron (DRM) system. Bottom hole diameters ranging from 0.17 µm down to 0.10 µm could be obtained by varying the oxide etch process, which included C@sub 4@F@sub 8@ or C@sub 5@F@sub 8@, O@sub 2@ and Ar. Moderate etch selectivity to SiN (>10:1) was needed because of the bi-level contact height (over gate or over active). Etched patterned wafers were characterized using top-down CD-SEM, cross-section SEM and TEM. Ex situ surface analysis of etched blanket wafers was made to test the model of fluorocarbon film control of etch selectivity. Electrical properties of the W-filled contacts will also be summarized.