Green semiconductor fabrication is the goal of the Semiconductor Research Corp. (SRC) which has found a way to add sensor to wafers that read-out whether it is clean or not. In between each process the wafer has to be cleaned of contaminants, but without sensors there is waste from overkill cleaning algorithms, but with a sensor wafers can save mucho energy and materials: R. Colin Johnson
Sensor channels measure the impedance of cleaning fluids in closed-loop process that stops cleaning when done rather than wasting resources. Source: SRC
Here is what EETimes says about putting cleaning sensors of wafers: Energy efficient semiconductor fabrication techniques have largely eluded designers of wafer cleaning processes, which still depend on open-loop recipes that waste energy and water. By closing the loop with on-wafer sensors, the Semiconductor Research Corp. (SRC, Research Triangle, N.C.) said it has developed a technology that saves as much as 80 percent of the water and energy required by traditional open-loop cleaning.