Richard D. Edwards

Characterization of autofocus uniformity and precision on ASML steppers using the phase-shift focus monitor reticle

This paper details a method that was used to evaluate and characterize autofocus uniformity and repeatability issues which were exhibited on ASML 5500/100 Stepper systems at Advanced Micro Devices in Austin, Texas. Equally significant is the process by which these issues were resolved through a cooperative effort with ASM Lithography, which is also discussed. Data shown in this paper was collected using the Phase Shift Focus Monitor Reticle, produced by Benchmark Technologies. The coactive relationship between ASML and AMD was integral in identifying the cause of this long-standing condition, as well as providing and implementing the required solution.

Lithography overlay controller formulation

Lithography overlay refers to the measurement of the alignment of successive patterns within the manufacture of semiconductor devices. Control of overlay has become of great importance in semiconductor manufacturing, as the tolerance for overlay error is continually shrinking in order to manufacture next-generation semiconductor products. Run-to-run control has become an attractive solution to many control problems within the industry, including overlay. The term run-to-run control refers to any automated procedure whereby recipe settings are updated between successive process runs in order to keep the process under control. The following discussion will present the formulation of such a controller by examining control of overlay. A brief introduction of overlay will be given, highlighting the control challenge overlay presents. A data management methodology that groups like processes together in order to improve controllability, referred to as control threads, will then be presented. Finally, a discussion of linear model predictive control will show its utility in feedback run-to-run control.

In the year 2525, if x ray is still alive, if lithography can survive, they may find...

Data and discussions will be presented on the NTRM, National Technology Roadmap, for reticles based on a Process Integration perception. Specifically two layers are considered for this paper, the gate layer which is primarily a chrome geometry mask with a lot of open glass and a local interconnect layer which is primarily a chrome plate using clear geometries. Information from other sources is used where appropriate and actual in-house data is used to illustrate specific points. Realizing that demands from different customers for specific types of features tend to drive specific mask makers and their decisions on equipment purchases and processes. We attempt to help predict where Integration approaches have either caused a lag in technology pushes or have actually speeded up certain requirements. Discussions of integration requirements, which tend to push maskmakers, will be presented. Along with typical design approaches in OPC and PSM which either will push technology or actually slow down the trend towards smaller geometries. In addition, data will be presented showing how specific stepper characteristics may actually drive the customers criteria, thus changing the requirements from customer to customer.

Manufacturing engineering use of data management to analyze and control stepper performance in existing fabs and on stepper evaluations for new tools

This paper describes the program used to improve data collection and analysis methods in a sub-micron manufacturing environment to control photolithography steppers. The program provides any user a standard method for analysis. The benefits of this methodology are a reduction in analysis time, uniform analysis by use of similar algorithms, and the reduction in the use of multiple database programs. The programs outputs include customized reports, focus exposure curves, data tables, and SPC charts. By storing all information, historical data can be accessible in these output forms. This paper briefly explains the medium used to transfer the data from the stepper and metrology systems. Explanation of the use and results of the on-line data analysis program and examples of the programs output are also given. The program was developed to support manufacturing from 0.8 micrometers to 0.35 micrometers i-line production. The authors feel the programs are flexible enough to add more outputs for different technologies.