In-situ monitoring for CVD processes

Aiming towards process control of industrial high yield/high volume CVD reactors, the potential of optical sensors as a monitoring tool has been explored. The sensors selected are based on both Fourier transform infrared spectroscopy (FTIR) and tunable diode laser spectroscopy (NIR-DLS). The former has the advantage of wide spectral capability, and well established databases. NIR-DLS spectroscopy has potentially high sensitivity, laser spatial resolution, and the benefits of comparatively easier integration capabilities-including optical fibre compatibility. The proposed technical approach for process control is characterised by a 'chemistry based' feedback system with in-situ optical data as input information. The selected optical sensors continuously analyze the gas phase near the surface of the growing layer. The spectroscopic data has been correlated with process performance and layer properties which, in turn establish data basis for process control. The new process control approach is currently being verified on different industrialised CVD coaters. One of the selected applications deals with the deposition of SnO2 layers on glass based on the oxidation of (CH3)2SnCl2, which is used in high volume production for low-E glazing

Sol-gel coatings on large area glass sheets for electrochromic devices

The preparation of vanadium and tungsten oxide coatings is described using vanadium oxide tri-2-propoxide/2-propanol and tungsten penta-ethoxide/2-propanol solutions. These solutions are dip coated onto K-glass substrates and cured. For vanadium oxide coatings it is shown that sol-gel/dip coat processing is a feasible production technology for very homogeneous vanadium oxide coatings on large area sheets with good electrochromic properties. Homogeneous vanadium/titanium oxide coatings with a titanium contents up to 40% and charge capacities up to 45 mC/cm2 are obtained. Homogeneous tungsten oxide coatings with reasonable electrochromic properties (coloration efficiency up to 34 cm2/C and transmission changes up to 5:1) are prepared

Low Temperature Deposition of TiN Ceramic Material by Metal Organic and/or Plasma Enhanced CVD

A review is presented describing the development of TiN-CVD from the classical, high temperature TiCl4/N2 process, towards low temperature MOCVD processes. This development is presented from a chemical point of view. In addition to low pressure (LPCVD) and atmospheric pressure (APCVD) thermal processing, also plasma enhanced (PECVD) techniques are described. In the past few years production facilities for good quality TiN layers for wear resistant applications have come on the market. Production facilities for IC-technology applications of CVD-TiN are on the edge of breaking through. For both applications deposition temperatures have been reduced to 500-600°C. Research developments, have shown even lower deposition temperatures possible for TiN and Ti(C,N) layers

High-speed spatial atomic-layer deposition of aluminum oxide layers for solar cell passivation

In this Communication we show that with spatially separated ALD of Al2O3 growth rates of 1.2 nm s-1 can be achievd, showing excellent surface passivation (surface recombination velocities of <2 cm s-1). This implies a revolutionary breakthrough in industrial throughput ALD of Al2O3 passivation of silicon solar cells

Development of APCVD process for high quality TCO

For the past decade TNO has been involved in the research and development of atmospheric pressure CVD (APCVD) and plasma enhanced CVD (PECVD) processes for deposition of transparent conductive oxides (TCO), such as tin oxide and zinc oxide. The use of atmospheric deposition processes allows for large scale roll to roll manufacturing, and is therefore expected to provide a breakthrough for lowering the price of thin film PV modules. 2009 IEEE

Kinetic mechanism of the decomposition of dimethyltin dichloride

Results are reported of a study of the intrinsic kinetics of gas phase reactions. For this purpose a reactor system is designed in such a way that concentration and temperature variations throughout the reactor can be neglected enabling investigation of intrinsic reaction kinetics. The gas phase composition in the reactor is analysed by Fourier Transform Infrared spectroscopy and Mass spectrometry. Investigation of the pyrolysis of dimethyltin dichloride (DMTC) in nitrogen between 370 and 630°C with this system revealed that decomposition starts at 500°C. A linear relationship has been found between the formation of methane, ethane, ethene, and propane and the inlet concentration of DMTC. Also the overall decomposition rate is first order in inlet concentration of DMTC. Linear least squares analysis gives a rate constant with an Arrhenius constant of 9±1⋅1015 s-1 and an activation energy of 62.8±3 kcal/mol. A mechanism is proposed that describes all the observations