9 July 1992 Mix-and-match lithography in a manufacturing environment
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Abstract
Fabrication of integrated circuits at subhalf micron geometries is currently feasible only using advanced lithography technologies such as direct write e-beam and x-ray systems. These systems are extremely expensive and have low effective throughputs for a production environment. A mix-and-match approach using optical steppers for noncritical levels can dramatically increase productivity and control total lithography costs. A major impact for mix- and-match lithography is the total root mean squared alignment errors between systems. Implementation of a larger overlay budget to accommodate mix-and-match errors adversely impacts design rules for submicron technologies. However, a maskless lithography tool such as direct write e-beam offers the potential to compensate for systematic errors during wafer patterning and dramatically reduce the overlay budget for those layers. At TRW, a mix-and- match scheme has been developed between a Hitachi HL-700D e-beam direct write system and a Ultratech 1500 wide field 1X stepper. A previous analysis using only the linear distortion terms between these systems was found to be inadequate to fully explain the observed overlay. In this study, both linear and higher order distortion components are extracted using a large number of distributed measurement sites in the stepper field. These distortion terms are then analyzed to determine their source. Compensation techniques including both system hardware adjustments and e-beam software are investigated to enhance registration capabilities.
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Warren W. Flack, Warren W. Flack, David H. Dameron, David H. Dameron, Valerie J. Alameda, Valerie J. Alameda, Ghassan C. Malek, Ghassan C. Malek, } "Mix-and-match lithography in a manufacturing environment", Proc. SPIE 1671, Electron-Beam, X-Ray, and Ion-Beam Submicrometer Lithographies for Manufacturing II, (9 July 1992); doi: 10.1117/12.136008; https://doi.org/10.1117/12.136008
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