Post Copper CMP Hybrid Clean Process for Advanced BEOL Technology

• Published in: IEEE transactions on semiconductor manufacturing Vol. 26; no. 4; pp. 493 - 499
• Main Authors: Wei-Tsu Tseng, Devarapalli, Vamsi, Steffes, James, Ticknor, Adam, Khojasteh, Mahmoud, Poloju, Praneetha, Goyette, Colin, Steber, David, Tai, Leo, Molis, Steven, Zaitz, Mary, Rill, Elliott, Kennett, Michael, Economikos, Laertis, Lustig, Naftali, Bunke, Christine, Truong, Connie, Chudzik, Michael, Grunow, Stephan
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01.11.2013; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Abrasives; Applied sciences; Aqueous solutions; Brushes; Chemical-mechanical polishing; CLEANING; Copper; Cu CMP; defect reduction; Defects; Electronics; Exact sciences and technology; Microelectronic fabrication (materials and surfaces technology); Planarization; POLISHING; post clean; Reduction; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; SEMICONDUCTORS; Surface cleaning; X RAY SPECTROSCOPY; X-ray photoelectron spectroscopy; post clean; defect reduction; Cleaning; Particle suspension; Cu CMP; Implementation; Microelectronic fabrication; Back end of line technology; Oxidation; Aqueous solution; Advanced technology; Copper; Formation mechanism; Chemical mechanical polishing; Surface conditions; X-ray photoelectron spectra
• ISSN: 0894-6507; 1558-2345
• DOI: 10.1109/TSM.2013.2273124

A "hybrid" post Cu CMP cleaning process that combines acidic and basic clean in sequence is developed and implemented. The new process demonstrates the strengths of both acidic and basic cleans and achieves a more than 60% reduction in CMP defects, such as polish residues, foreign materials, slurry abrasives, scratches, and hollow metal, relative to an all-basic clean process. It also eliminates the circular ring defects that occur intermittently during roller brush cleans. TXRF scans confirm the reduction of AlO x defects when using the hybrid clean process. XPS spectra show similar Cu surface oxidation states between the basic and hybrid clean processes. As revealed by XRD analysis, surface Cu oxide is dissolved into aqueous solution by the acidic clean chemical. The formation mechanism of circular ring defects and the key to their elimination is discussed.