A method for monitoring and improving CD SEM system matching performance using Duncan's Multiple Range Test is presented using results obtained from KLA 8000 systems. The demonstrated benefits of this method include: eliminating the need for a 'mother' system to which al others are matched; providing the capability to analyze a large number of systems simultaneously; identifying poorly performing systems; and providing the statistical significance of the result. Sample plan considerations are discussed and methods to minimize the effect of both sample degradation and undesired sources of variation are presented. A graphical method for analyzing the output of Duncan's Multiple Range Test is developed and applied to process control. Use of a fileserver to ensure job recipe consistency across tools, and enable the elimination of slope and offset correction factors, lay the groundwork for improvements in system monitoring capability. Improvements of greater than a factor of two in system matching are demonstrated and long term CD SEM matching of less than 10 nm on average across critical process layers is achieved.

Date Published: 7 July 1997
PDF: 8 pages
Proc. SPIE 3050, Metrology, Inspection, and Process Control for Microlithography XI, (7 July 1997); doi: 10.1117/12.275941

Published in SPIE Proceedings Vol. 3050:
Metrology, Inspection, and Process Control for Microlithography XI
Susan K. Jones, Editor(s)