Corona-Charge Evaluation of Thermal SiO sub 2 Growth by Single Wafer and Batch Methods

The electrical measurements of blanket 3 nm SiO sub 2 films were used to compare thermal oxidation of silicon wafers by rapid single wafer and batch furnace methods. Prime p-type Czochralski 200-mm Si wafers were prepared by automated wet cleans with final chemical oxidation. The thermal oxidation in O sub 2 ambient was split among three tools: (1) a batch vertical furnace at 800C; (2) an incandescent-lamp rapid processor for 20 s at 1000C and reduced partial O sub 2 pressure; and (3) a furnace-elevator rapid processor using various temperatures and times ranging from 1 s to 20 s. Ellipsometry was used to map oxide thickness. A Quantox system was used for corona-charge electrical measurement on the unpatterned as -grown oxide films of fixed charge, mid-gap density of interface states, generations lifetime, bulk and near surface recombination lifetimes, tunneling field, mobile charge, and Fe-B pair lifetime signatures. The results show that the density of interface states of rapid thermal oxides, grown by either method, are nearly an order of magnitude larger than the batch furnace method 3. Wafers were subsequently given a forming gas anneal and corona-charge measurements were taken at new sites on the wafers. The second measurements show reduced and comparable densities of interface states, and increased and comparable lifetimes. Results indicate contamination associated with the three methods are low and comparable.