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Effect of Retaining Ring Slot Design on Slurry Flow during Chemical ...

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Internati<strong>on</strong>al C<strong>on</strong>ference <strong>on</strong> Planarizati<strong>on</strong>/CMP Technology 2008November 10~12, 2008, Taiwan<str<strong>on</strong>g>Effect</str<strong>on</strong>g> <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>Retaining</str<strong>on</strong>g> <str<strong>on</strong>g>Ring</str<strong>on</strong>g> <str<strong>on</strong>g>Slot</str<strong>on</strong>g> <str<strong>on</strong>g>Design</str<strong>on</strong>g> <strong>on</strong> <strong>Slurry</strong> <strong>Flow</strong> <strong>during</strong><strong>Chemical</strong> Mechanical Planarizati<strong>on</strong>Yun Zhuang 1&2,a , Xiaomin Wei 2,b , Roy Dittler 2,c , Jiang Cheng 2,d ,Christopher Wargo 3,e , Ralph Stankowski 3,f and Ara Philipossian 1&2,g1 Araca, Inc., 6655 North Cany<strong>on</strong> Crest Drive, Suite 1205, Tucs<strong>on</strong>, Ariz<strong>on</strong>a 85750, USA2 University <str<strong>on</strong>g>of</str<strong>on</strong>g> Ariz<strong>on</strong>a, 1133 James E. Rogers Way, Tucs<strong>on</strong>, Ariz<strong>on</strong>a 85721, USA3 Entegris, Inc., 129 C<strong>on</strong>cord Road, Billerica, Massachusetts 01821, USAa yunzhuang@aracainc.com , b weix1@email.ariz<strong>on</strong>a.edu , c dittler@email.ariz<strong>on</strong>a.edud jcheng@email.ariz<strong>on</strong>a.edu , e christopher_wargo@entegris.com , f ralph_stankowski@entegris.comg aphilipossian@aracainc.comKeywords: retaining ring slot design, slurry flow, dual emissi<strong>on</strong> UV enhanced fluorescence,chemical mechanical planarizati<strong>on</strong>.Abstract. The effect <str<strong>on</strong>g>of</str<strong>on</strong>g> retaining ring slot design <strong>on</strong> slurry flow <strong>during</strong> chemical mechanicalplanarizati<strong>on</strong> (CMP) was investigated. Two PEEK retaining rings with “Standard” and“Alternative” slot designs were attached to a 200-mm quartz wafer and the thickness <str<strong>on</strong>g>of</str<strong>on</strong>g> the slurryfilm between the land area <str<strong>on</strong>g>of</str<strong>on</strong>g> the pad and wafer was measured using dual emissi<strong>on</strong> UV enhancedfluorescence (DEUVEF) technique at different slurry flow rates (150 and 220 ml/min), pad/waferrotati<strong>on</strong>al rates (80 and 120 RPM) and retaining ring/wafer pressures (1.8 and 3.6 PSI). On average,the “Alternative” ring achieved approximately 40 percent higher slurry film thickness comparedwith the “Standard” ring, indicating that its slot design further facilitated slurry flow into thepad/wafer interface regi<strong>on</strong> <strong>during</strong> polishing. In general, for both retaining rings, the slurry filmthickness increased with higher flow rate, lower pad/wafer rotati<strong>on</strong>al rate, and lower retainingring/wafer pressure. A high-resoluti<strong>on</strong> video camera was used to record slurry flow <strong>on</strong> the pad15


Internati<strong>on</strong>al C<strong>on</strong>ference <strong>on</strong> Planarizati<strong>on</strong>/CMP Technology 2008November 10~12, 2008, Taiwansurface <strong>during</strong> the tests. Video images c<strong>on</strong>firmed the DEUVEF results that the “Alternative” ringallowed more slurry to flow into the pad/wafer interface regi<strong>on</strong> compared with its “Standard”counterpart. During the tests, shear force generated am<strong>on</strong>g the retaining ring and wafer assembly,the slurry abrasives, and pad surface was also measured. Results indicated that there was nosignificant difference in shear force associated with the two ring designs.16

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