Run-to-run control utilizing the AVM system in the solar industry

• The AVM system has been installed in all of the plasma enhanced chemical vapor deposition (PECVD) tools of Motech Industries, Inc. Fab 1. • Currently, a joint development project to deploy a run-to-run (R2R) control scheme utilizing the AVM system is underway. • R2R control [1] is the technique of modifying recipe parameters or the selection of control parameters between runs to improve processing performance. The R2R control is also called the tube-to-tube (T2T) control for the PECVD tools in the solar industry. • In the deposition process of the solar-cell manufacturing, the sampling rate is less than 10%. However, the T2T control requires 100% total inspection. To accomplish this requirement, large amount of measurement is needed, and thus leads to the increase of the production cycle time and cost. • To resolve the problem mentioned above, Virtual Metrology [2] for the T2T control was proposed. • Incorporation of VM into R2R control is one of key APC focus areas of ITRS for 2009 [3]. • A key problem preventing effective utilization of VM in R2R control is the inability to take the reliance level in the VM feedback loop of R2R control into consideration [4]. • The reason is that the result of adopting an unreliable VM value may be worse than if no VM at all is utilized [4]. • The authors have proposed the so-called reliance index (RI) of VM to gauge the reliability of the VM results [5]. • This paper proposes a novel scheme of R2R control that utilizes VM with RI/GSI [5][10] in the feedback loop.