AVS 45th International Symposium
    Manufacturing Science and Technology Group Thursday Sessions
       Session MS-ThM

Paper MS-ThM5
NOVA In-Line CMP Metrology and Its Use for Lot-to-Lot Process Control

Thursday, November 5, 1998, 9:40 am, Room 317

Session: Sensors and Support Technology
Presenter: T.H. Smith, Massachusetts Institute of Technology
Authors: T.H. Smith, Massachusetts Institute of Technology
S.J. Fang, Texas Instruments
J.A. Stefani, Texas Instruments
G.B. Shinn, Texas Instruments
D. Boning, Massachusetts Institute of Technology
S.W. Butler, Texas Instruments
Correspondent: Click to Email
The use of in-line metrology with run by run (RbR) process control is becoming a means to meet the future demands on improved processing quality without sacrificing throughput. This control will become critical for large variation processes such as chemicalmechanical polishing (CMP). In response to this, other works have described the use of the NOVA in-line CMP metrology system for use in RbR process control. This work describes a similar system, but focuses on quantifying 1) the quality of measurements obtained from the NOVA system, 2) improvements gained by simple RbR control of post-polish patterned wafer thickness over fixed-time polishing and pilot wafer control, and 3) the increases in throughput using an in-line measurement and control system. The results of a gauge study of the NOVA system and a 600 wafer RbR control experiment performed at Texas Instruments, Inc. are discussed. The variability of the system is shown to be well within standard requirements. The reliability of the system over the 600 wafer experiment was very good. The NOVA measurements are shown to correlate well with ex-situ measurements. The 600 wafer RbR control experiment indicates that even a simple control approach provides a 25% improvement over the fixed-time approach. The results demonstrate that controlling directly on patterned wafers provides a 23% improvement over control using pilot wafers. The experiment shows a 25-40% improvement in throughput using the system. The number of cleans were reduced by 0-66% (depending the number of look-aheads and amount of re-work) and ex-situ measurements were eliminated, indicating significant cost of ownership reductions.