Acoustic monitoring of electrochemical deposition

In the microelectronics industry, manufacturers are concerned with increasing yield and reducing costs. Monitoring of unit manufacturing processes helps alleviate errors during fabrication, thereby increasing yield and ultimately decreasing cost. This work proposes an acoustic method for in-situ monitoring of electrochemical deposition. A micromachined acoustic sensor was developed for this purpose. During electroplating processes, changes in the plating solution composition result in changes in an acoustic signal transmitted through the bath. A predictive model of the progression of metallization during electroplating was established based on signals from the acoustic sensor. The sensor data and measured plated metal thickness were recorded and mapped to yield an empirical relationship between the two, thereby enabling real-time monitoring of electroplating.