No abstract

The deployment of angular scatterometry as a powerful and effective process control methodology has recently included the measurement of etched metal features in a typical complex Aluminum stack. With the control of metal process steps taking a more critical role in silicon manufacturing, a fast, reproducible and accurate methodology for measuring CD and depth is necessary. With the half-pitch of the metal pattern being as low as the minimum device feature, etch rate measurements on above-micron test structures are hardly indicative of the pattern-dependent etch profiles and behavior. Angular scatterometry offers a non-destructive, fast and powerful approach for measuring the profiles of the yield-relevant array features in metal applications.In this work we demonstrate the application of angular scatterometry to the qualification of metal etchers. Etch depth is difficult to control and must be inspected with slow techniques such as profilometry. In addition to the slow response time and sparse radial sampling, contact profilometry is susceptible to residual resist and polymer residue as well as to the variations in the TiN ARC layer affecting the measurement of the Aluminum etch rates. We show that the choice of a suitable profile model and accurate knowledge of the optical properties allow scatterometry to overcome all of these traditional challenges.We demonstrate that angular scatterometry is sensitive to the parameters of interest for controlling metal etchers, specifically etch depth, CD and profile. Across an experimental design that introduced intentional variations in these parameters, angular scatterometry results were able to track the variations accurately. In addition, profile results determined through scatterometry compare favorably with cross-sectional SEM images and measurements. Measurement precision results will also be presented.

This paper describes the results of experiments performed to proof the tool-to-tool matching status of two CD SEM systems located in different wafer fabs in Asia, Europe, Israel and the United States. The methodology for setting up tools within one fab to ensure the matching of the signal generation between the tools has been extended to set up tools located in different fabs. In a second step a new methodology was developed to proof the matching, defined as getting the same measurement result on all tools, in different fabs. The main problem was the change of the structures on the wafers used for matching proof caused by the shipment. After verifying that the change to be the same no matter where the two tools under test are located, the change could be treated as an additional systematic effect not affecting the matching proof any longer. It is shown that by extension of the existing methodologies and by including the correction for systematic effects due to wafer shipment a matching level of all tools around the world similar to the matching level of tools within one fab can be achieved.

A tabulation of microwave electron tubes with characteristics of each type has been arranged in the form of two major listings, a Numerical Listing in which the tubes arc arranged by type number, and a Characteristic Listing in which the tubes are arranged by the kind of tube, and further ordered on the basis of minimum frequency and power output. P0. The maximum power output. Collector, Reflector, etc. Volts. The maximum collector, reflector, line, etc. voltage whichever is most applicable. Control Volts Egl. The maximum control, focusing or grid voltage. Helix Voltage. The maximum helix or delayline voltage of traveling wave tubes.

Lithography process control remains a significant challenge in modern semiconductor manufacturing. Metrology efforts must overcome the complexity of the lithography process, as well as the number of process elements that contribute to overall process yield. One specific area of concern is lithography tool focus control. It is vital to control photolithography tool focus during the photoresist development step with a high degree of precision and accuracy. Furthermore, dose variations can compound the difficulty in determining focus. The lenses used in photolithography tools have a very limited depth of focus, so utmost precision is necessary. Tools that are in focus will result in sharper and better controlled features, while tools that are out of focus will result in improperly developed photoresist features.Angular scatterometry is a technology well-suited for lithography inspection and process control because it provides rapid measurement data and can be used for the measurement of resist line profiles. We report on model-based methods for focus control and their application towards photolithography control in a production setting. Topics of discussion include the effect of model parameter selection for focus metrics on focus curve quality and accuracy, as well as the effect of grating target design on focus sensitivity and accuracy. Measurement data using this focus technique in a production setting will be presented.