Efficient Non-reagent Metrology for Modern TSV Baths

Through-silicon via (TSV) technology is gaining popularity in 3D packaging and 3D integrated circuits. TSV baths are formulated with highly stable electrolytes that contain copper and sulfuric acid. Other components introduced into the bath in relatively small amounts are organic additives and chloride ions. This article will focus on a non-reagent metrology to efficiently monitor these components. The chloride concentration is determined from the chloride oxidation current using specific voltammetric parameters. Similar to analysis of suppressor, the measurement is made directly in the undiluted plating bath. Results for non-reagent analysis for acid and copper were reported earlier. Electrochemistry and spectroscopy are employed in on-line monitoring of various TSV baths. The concentrations of organic additives are determined from the rate of the copper deposition. The new techniques differ from conventional CVS procedures. The advantages of these newly developed electrochemical procedures are speed (re...