AVS 50th International Symposium
    Manufacturing Science and Technology Wednesday Sessions
       Session MS-WeM

Paper MS-WeM1
Critical Dimension and Remaining Film Thickness Within Wafer Uniformity Improvement by Advanced Process Control Based on Optical Integrated Metrology

Wednesday, November 5, 2003, 8:20 am, Room 326

Session: Sensors, Metrology, and Control
Presenter: J. Luque, Lam Research Corporation
Authors: J. Luque, Lam Research Corporation
G.P. Kota, Lam Research Corporation
V. Vahedi, Lam Research Corporation
Correspondent: Click to Email
The first generation of advanced process control using integrated metrology in polysilicon etch processes has been focused on correcting wafer averaged critical dimension (CD). Schemes have ranged from feed-forward to feed-forward/feedback closed loop control. In all these cases the information from optical CD is used to obtain a target wafer averaged CD and minimize the lot-to-lot and within lot- variations of post-etch CD by correcting perturbations from lithography and etch steps. In the present work we explore some of the cases where improvement of isolated to dense loading, within wafer CD uniformity after gate etch or uniformity of the remaining films in recess etch applications is important. Because device performance is directly related to the CD, it is necessary to improve the uniformity of the CDs as much as is important to reach the specific target CD. Correction of the CD within wafer uniformity can be achieved by feedback of the CD information to the track/scanner cluster (litho step) or by feed-forward to the etch module. We show how non-uniformities generated in a concentric pattern by the litho step can be partially or completely eliminated during the etch step using a tunable temperature gradient in the chuck of a Lam Versys 2300 etching system. This approach to improve CD uniformity opens a path to more complex advanced process control that will deliver simultaneous CD and uniformity control. The results from this method should be better than those from schemes based on just averaged CD control. Similar approach is investigated in etch processes that can be characterized by simple thin film measurement instead of full optical profile characterization.