AVS 51st International Symposium
    Manufacturing Science and Technology Tuesday Sessions
       Session MS-TuP

Paper MS-TuP3
The Evaluation of a Twin Wire Arc Spray (TWAS) Process for Coated Shields used in Soft-Sputter Etch Pre-Clean Chambers

Tuesday, November 16, 2004, 4:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: A. Sidhwa, STMicroelectronics, Inc
Authors: A. Sidhwa, STMicroelectronics, Inc
M. Goulding, STMicroelectronics, Inc
M. Kalaga, STMicroelectronics, Inc
X. Breurec, STMicroelectronics, Inc
R. Pierce, STMicroelectronics, Inc
T. Gandy, STMicroelectronics, Inc
Correspondent: Click to Email
A Soft Sputter Etch (SSE) process plays a vital role in the cleaning of contacts and vias prior to the deposition of contact barriers and via liners. This paper describes the work performed at STMicroelectronics to eliminate Silicon Oxide (SiO2) defects, which are observed at the end of the Pre-Clean chamber component (quartz and shield) lifetime; the latter is specified in RF hours. During the component re-cycling process, the aluminum (Al) RF shield receives a particular surface finish after the cleaning step. It is well known that the Bead-Blast/Post-Blast Etch (PBE) process produces a relatively rough surface finish, which enhances the oxide sticking properties during subsequent wafer sputter-etch. However during such processing, a large surface area of roughness (containing a small number of nucleation sites) is produced on the surface of the shield, resulting in defects (Silicon Oxide flakes) being observed at the end of the Pre-Clean chamber lifetime: i.e., the sputter-etched oxide becomes clustered around a comparatively small surface area, with continuous growth in a vertical direction producing "Worm" defects. The latter defects constitute "stress risers," which are a key source of oxide de-fragmentation. Hence, when trying to increase the sputter-etch chamber component lifetimes from the current 60 RF hours to a significantly higher value of 250 RF hours, the problem of Worm defects becomes more significant. However by contrast, an Al RF shield with a TWAS surface finish shows no similar issues at comparable lifetime. This paper describes the evaluation and implementation of TWAS for the Al RF shield, and explains the significant impact/elimination of Worm defects due to the change in the RF shield surface condition.