Reduced Water Consumption for Post Clean Treatment and Metal Ion Contamination on VLSI Structures

摘要

The typical fab consumes 240 million gallons of water for both BEOL and FEOL processes (approximately 1500 gals/200mm wafer), yet in the year 2000 the SRI National Technology Roadmap calls for only 500 gals/200 - 300mm wafer. Currently wet benches, batch spray tools and single wafer processing tools are options for BEOL and post CMP cleaning. The data in this presentation will show the relationship between simple chelating chemistries, wafer rotation speed (rpm), and pH. Studies will also show how new environmentally friendly BCS chemistries (Buffered Chelating Solutions, with pH 4.2 or 8.5) for post etch residue cleaning of metal wafers can reduce DI water consumption while reducing metal ion (iron and copper) contamination. BEOL wet bench process, BCS chemistry at pH4 can effectively reduce Fe~(3+) and Cl~- from contaminated BPSG surface, more effectively than simple solutions of high ionic strength. It is obvious that pH value and chelation played important roles in removing trace metal contamination. BCS solutions in wet benches and spray tools have been shown to enhance the rinse process with a better CoO for the process engineer.