Ravi Kanjolia

Atomic layer deposition of molybdenum oxide using bis(tert-butylimido)bis(dimethylamido) molybdenum

Molybdenum trioxide films have been deposited using thermal atomic layer deposition techniques with bis(tert-butylimido)bis(dimethylamido)molybdenum. Films were deposited at temperatures from 100 to 300 °C using ozone as the oxidant for the process. The Mo precursor was evaluated for thermal stability and volatility using thermogravimetric analysis and static vapor pressure measurements. Film properties were evaluated with ellipsometry, x-ray photoelectron spectroscopy, secondary ion mass spectroscopy, and secondary electron microscopy. The growth rate per cycle was determined to extend from 0.3 to 2.4 A/cycle with <4% nonuniformity (1-sigma) with-in-wafer across a 150 mm wafer for the investigated temperature range.

Correlation of reduced oxygen content in precursors with improved MOVPE layer quality

Trimethylaluminium (Me 3 Al or TMA) and trimethylindium (Me 3 In or TMI) are the key precursors in the fabrication by MOVPE of higher brightness LEDs, VCSELs and solar cells and they must be oxygen free to achieve optimum results. An improved proton nuclear magnetic resonance spectroscopy technique (NMR) has been developed to allow the detection of impurity species at ppm levels. MOVPE growth tests of material thus characterised have been performed and a correlation of SIMS and PL data for layers to NMR indicated purity is presented. A strong relationship was observed between oxygen levels in precursors and deposited layer structures. The best quality EpiPure TMA precursor, with non-detectable O levels, yielded <3 × 10 16 cm -3 oxygen by SIMS in AlAs layers. Furthermore, Al 0.8 Ga 0.2 As and (Al 0.8 Ga 0.2 ) 0.5 In 0.5 P layers deposited in a second reactor using a number of TMA and TMI samples and historical data confirmed this trend and low oxygen levels (<2 × 10 17 cm -3 ) were obtained for high-purity EpiPure sources.

Low oxygen content trimethylaluminium and trimethylindium for MOVPE of light emitting devices

The reduction in oxygen contamination levels in organometallic precursors has been established as a key requirement in the metal organic vapour-phase epitaxy (MOVPE) of high brightness light emitting diode (LED) and laser devices. A number of different volatile oxygen-containing impurity species have been identified, and both physical and chemical techniques have been developed to eliminate them from a wide range of source materials to produce the next generation grade of high-purity products. In this study conclusive growth results are presented to highlight the significantly improved quality of device structures obtained when higher purity oxygen-free precursors are employed.

Photochemical reactivity of bis-carbamate photobase generators

The extension of 193nm technology is desirable due to the magnitude of past investments. Since “optical” advances are increasingly difficult, there is a strong demand for more sophisticated “smart” resists to increase pattern density. Many studies have proven double pattering can be used for the extension of 193nm lithography. In this study, a new class of two stage photobase generators will be introduced along with the synthetic procedure. The characterizations for exposure study by NMR have shown typical characteristics of two stage decomposition under the exposure of 254nm light. GCMS was utilized to indicate the formation of photobase and major products from secondary photochemical reactions. Kinetic simulation was also taken into account to show the consistence of proposed mechanism.