We
present a real time, in situ method to control the spatial temperature
uniformity of a semiconductor substrate during the various bake steps
in the lithography sequence. Significantly, the wafer temperature
settles down to steady state within 50 s under closed-loop control.
The corresponding maximum temperature nonuniformity during transient
is less than 1 °C and the steady state temperature nonuniformity
is less than 0.1 °C. Specifically, we have developed a complete
thermal diffusion model for the entire bake plate-and-wafer system,
so that the transient thermal behavior is accurately captured during
the baking process. By monitoring the bake plate temperature and fitting
the data into the model, an updated model can be estimated and the
desired wafer temperature can then be calculated and controlled in
real time. Experimental results confirm the efficacy of the approach
and its superiority over traditional run-to-run control techniques.
Abstract-The use of wireless sensor networks for indoor localization application has emerged as a significant area of interest over the last decade, primarily motivated by its low cost and convenient deployment. The weighted centroid localization algorithm is a suitable positioning technique in a wireless sensor network due to its easy implementation. However, the performance of this method is easily affected by outliers and interference in the measurement of radio signal strength. In order to overcome this limitation, a more robust ARMA filter using generalized t-distribution noise model based on influence function approach is proposed. A hardware prototype was implemented to demonstrate that the ARMA filter could improve system performance, especially when dealing with the case of measurement outliers.
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