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Gauge-capability study of ion-implant monitors

1991; Elsevier BV; Volume: 55; Issue: 1-4 Linguagem: Inglês

10.1016/0168-583x(91)96152-b

1872-9584

W. H. Johnson, W. A. Keenan, T. Wetteroth,

Advanced Sensor Technologies Research

The ability to control a process is determined by the variability of the process and the variability of the system used to monitor the process. The monitoring system consists of the monitor wafer, the operator, the environment and the test system (gauge). The monitor wafer can be sensitive to short-term and long-term drift, post processing and temperature. This decouples the monitoring system from the process and simplifies the control problem. A gauge-capability study helps establish the repeatability (tester variability) and reproducibility (operator variability) of the monitoring system. A gauge study was conducted on five sets of production ion implant monitor wafers ranging from 26 to 3000 Ω/□. Ten wafers were available for each implant. These were manually measured twice by three operators and twice by an automated wafer handling system. The results were analyzed with respect to operator training and attention, automated wafer handling, probe performance and qualification, temperature variation and the range of sheet resistance of the monitors. To adequately control the implant process, the ratio of total repeatability and reproducibility (precision) to the process (tolerance) specification should be less than 0.1 P/T ratio). This can be achieved with good equipment that is well maintained, dedicated and adequately trained operators, and well controlled fab temperature or temperature compensation.