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sputtering from a metallic In/Sn target using an oxygen-rich sputtering gas feed, 53<br />

spin- or dip-co<strong>at</strong>ing a solution <strong>of</strong> indium and tin compounds followed by thermal<br />

activ<strong>at</strong>ion, 54,55 or by UV-photolysis <strong>of</strong> an ITO polymeric film. 56 <strong>The</strong> first method is<br />

most common. Studies <strong>of</strong> deposited films reveal a strong dependence <strong>of</strong> optical and<br />

electrical properties on prepar<strong>at</strong>ion conditions, particularly rel<strong>at</strong>ed to oxid<strong>at</strong>ion and<br />

Sn incorpor<strong>at</strong>ion. 57-60<br />

2.2.3 Experimental Method 61<br />

Early in process development round quartz wafers were used in place <strong>of</strong> the<br />

square photomask substr<strong>at</strong>es because the chucks designed to hold photomask<br />

substr<strong>at</strong>es had not yet been delivered. For the Cr process flow experiments, quartz<br />

wafers were co<strong>at</strong>ed with 100 Å Cr using a MRC 603 DC magnetron load-locked<br />

sputtering system <strong>at</strong> 1200 W and 35 mTorr process run in a single pass mode. <strong>The</strong><br />

samples were co<strong>at</strong>ed with 180 nm NEB-22 resist, and were exposed on a Leica VB6<br />

system oper<strong>at</strong>ing <strong>at</strong> 100 kV with an e-beam dose ranging from 25 to 65 µC/cm 2 .<br />

Early in the SFIL ITO-templ<strong>at</strong>e development process ITO films were<br />

obtained from Silicon Quest (SQ), and were DC sputtered <strong>at</strong> 1 kW in 100% Ar <strong>at</strong> a<br />

pressure <strong>of</strong> 8 mTorr. Subsequent development was done internally in a customized<br />

RF sputter system oper<strong>at</strong>ing <strong>at</strong> a power <strong>of</strong> 100 W and an Ar/O2 pressure <strong>of</strong> 6 mTorr<br />

using an In2O3/SnO2 (90:10) target. Some films were annealed <strong>at</strong> various<br />

temper<strong>at</strong>ures in an oven containing ambient <strong>at</strong>mosphere. Resistivity measurements<br />

were made using a Magnetron 4-point probe instrument. Ultraviolet/visible<br />

(UV/Vis) transmission spectra were obtained using a Perkin Elmer Lambda 18<br />

UV/Vis spectrometer. For this analysis, ITO samples were prepared on smooth<br />

29

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