Angled XPS Analysis of Low-k Dielectric Surfaces after Cleaning

[1] An example of chemical nature of stripper A and stripper B: W.A. Wojtczak, G. Guan, D.N. Fine, S.A. Fine, U.S. Patent No. 6224785, 1 May 2001. Acknowledgements This work is sponsored partly by Agency for Science, technology and Research (A*STAR) in the form of a financial grant (Graduate Research Fellowship). The authors acknowledge Tong Qing and Samantha Fam for their help. Figure 1: SEM micrographs of simulated patterned Cu trenches at a magnification of 3,750 X and 40,000 X.Table 1: Relative atomic percentage concentrations of the Cu and C contaminants on post-etch trenches after subjected to different cleaning treatment, analyzed at a takeoff angle q = 900and 300 (Numbers in brackets refer to changes in relative atomic percentage with respect to post-etch values after different cleaning treatment). Species (%) After Etch N2/H2 plasma Stripper A Stripper B N2/H2 + DHF N2/H2 + Stripper A N2/H2 + Stripper B @900 49 58 53 51 74 72 59 Cu [Cu, Cu2O] @300 42 56 54 48 81 68 63 @900 51 42 (-9) 47 (-4) 49 (-2) 26 (-25) 28 (-23) 41 (-10) Cu(+2) [CuO, Cu(OH)2, CuF2] @300 58 44 (-14) 46 (-12) 52(-6) 19 (-39) 32 (-26) 37 (-21) @900 37 53 65 70 66 70 72 C [CH] @300 61 62 25 66 52 80 69 @900 37 26 (-11) 26 (-11) 21 (-16) 23 (-14) 30 (-7) 28 (-9) C [C-O-C, Si-O-C] @300 27 23 (-4) 46 (+19) 18 (-9) 31 (+4) 13 (-14) 23 (-4) @900 26 20 (-6) 9 (-17) 9 (-17) 12 (-14) - C [CO-C, CO-O-C] @300 12 15 (+3) 29 (+17) 15 (+3) 17 (+5) 7 (-5) 8 (-4) @900 1960 1902 179 1042 136 - 744 F [CuF2] - peak area @300 1192 826 - - - - -970 960 950 940 930 920 (a) Binding energy (eV) (b) (c) (d) (e) (f) Normalized Intensity (1)

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