Ensemble of Competitive Associative Nets for Stable Learning Performance in Temperature Control of RCA Cleaning Solutions

For cleaning silicon wafers via the RCA clean, temperature control is important in order to obtain a stable performance, but it is difficult mainly because the RCA solutions expose nonlinear and timevarying exothermic chemical reactions. So far, the MSPC (model switching predictive controller) using the CAN2 (competitive associative net 2) has been developed and the effectiveness has been validated. However, we have observed that the control performance, such as overshoot and settling time, does not always improve as the number of learning iterations increases when using multiple units of the CAN2. So we apply the ensemble learning scheme to the CAN2 for stable control over learning iterations, and we examine the effectiveness of the present method by means of computer simulation.