Invited Paper EL+AS+EN+PS+SS+TF-ThM5
Expanded Beam Spectroscopic Ellipsometry for In-line Monitoring of Thin Film Process

Thursday, October 31, 2013, 9:20 am, Room 101 A

Non-destructive analysing tools are needed at all stages of thin film process-development, especially photovoltaic (PV) development, and on production lines. In the case of thin films, layer thicknesses, micro-structure, composition, layer optical properties, and their uniformity are important parameters. An important focus is to express the dielectric functions of each component material in terms of a handful of wavelength independent parameters whose variation can cover all process variants of that material. With the resulting database, spectroscopic ellipsometry coupled with multilayer analysis can be developed for on-line point-by-point mapping and on-line line-by-line imaging.

This talk will try to review the investigations of different types of PV-layers (anti-reflective coating, transparent-conductive oxide (TCO), multi-diode-structure, absorber and window layers, backreflector) showing the existing dielectric function databases for the thin film components of CdTe, CIGS, thin Si, and TCO layers.

Off-line point-by-point mapping can be effective for characterization of non-uniformities in full scale PV panels in developing labs but it is slow in the on-line mode when only 15 points can be obtained (within 1 min) as a 120 cm long panel moves by the mapping station. Last years [1, 2], a new instrumentation was developed that provides a line image of spectroscopic ellipsometry (wl=350-1000 nm) data. Upto now a single 30 point line image can be collected in 10 s over a 15 cm width of PV material [3, 4]. This year we are building a 30 and a 60 cm width expanded beam ellipsometer which speed will be increased by 10 X. Then 1800 points could be mapped in a 1 min traverse of a 60*120 cm PV panel or flexible roll-to-roll substrate. Another enhancement is the switch-over to rotating compensator measuring principle.

[This work was supported by the ENIAC E450EDL and KMR_12_1_2012_0225 projects]

[1] C. Major, G. Juhasz, Z. Horvath, O. Polgar, M. Fried, PSS (c), 5, 5 (2008).

[2] G. Juhász, Z. Horváth, C. Major, P. Petrik, O. Polgar and M. Fried, PSS(c), 5, 5 (2008).

[3] M. Fried, G. Juhász, C. Major, P. Petrik, O. Polgár, Z. Horváth, A. Nutsch, Thin Solid Films519, 2730 (2011).

[4] M. Fried, G. Juhasz, C. Major, A. Nemeth, P. Petrik, O. Polgar, C. Salupo, Lila R. Dahal, R. W. Collins, Mater. Res. Soc. Symp. Proc.Vol. 1323, DOI: 10.1557/opl.2011.820. (2011).