Advanced aqueous wafer cleaning in power semiconductor device manufacturing

While the standard RCA wafer cleaning technique (Kern, 1970), is still predominantly used in semiconductor device manufacturing, several potential problems with this technique have been identified, such as surface roughness, contamination, chemical and DI water cost. Also, most of the work carried out in the area of wafer cleaning has been focused on the low power IC industry, where the active area of the device lay in the top 1 or 2 μm of the wafer. However, in the discrete power device industry, the use of lateral and vertical current flow for high current density distribution means that the entire substrate becomes part of the device active area. Therefore, metallic contamination even in the silicon bulk can severely degrade device performance. In this study, a modified RCA wafer cleaning mixture with improved megasonic energy enhancement (Schulze and Deboy, Proc. SPIE vol. 2638, pp. 234-41, 1995) and various rinsing techniques is investigated for use in high-volume power semiconductor device manufacturing. The effectiveness of the modified dilute SC-1/SC-2 procedure is demonstrated by various material, electrical and optical analysis techniques such as ELYMAT, TXRF, laser particle counting and Wright etching. The overall advanced aqueous wafer cleaning technique shows excellent contamination removal, cleaning efficiencies ⩾95% at 0.15 μm, and a reduced cost of ownership