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

Vorrichtung und Verfahren zur Bestimmung der Permeationsrate mindestens eines Permeaten, durch ein eine Diffusionssperre bildendes Element

DE 102007026073 A1 UPAB: 20081222 NOVELTY - The device has a permeation barrier forming element (1) e.g. foil, sectionally forming a partition between a permeate chamber (2.1) and a detection chamber (2.2) or a connection (10) to the detection chamber for supplying liquid or gaseous permeate contained in the permeate chamber. A laser light source (4) e.g. laser diode, directs a laser beam (3) at a wavelength on an optical detector (5) for determination of a permeation rate with an absorption wavelength of the permeate. The wavelength of the beam corresponds to an absorption wavelength of the permeate. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for determination of permeation rate of permeate. USE - Device for determining permeation rate of liquid or gaseous permeate for determining permeability of a polymer material for development phase of the polymer material with a barrier layer, for quality control, for packing food and oxidation/moisture-sensitive product, for encapsulation, and for an organic LED and a LCD display. ADVANTAGE - The device determines very small permeation rates with higher measuring sensitivity and measuring accuracy, and at reduced time

Quantitative-analysis of the in-situ fourier-transform infrared-absorption And emission-spectrum of gas-phase SiO (delta-v=1 and 2) produced in Si-N-O fiber growth

The in situ Fourier transform infrared (FT-IR) spectrum of gas-phase SiO produced in silicon oxynitride fiber growth has been quantitatively analyzed. Both absorption and emission FT-IR spectra at a spectral resolution of 0.5 cm(-1) were produced from the reaction zone at 1450 degreesC. The fundamental and hot bands were observed with vibrational levels up to v = 7. For the purposes of quantitative analysis the individual vibration-rotation integrated line strengths for the three main isotopes, (SiO)-Si-28, (SiO)-Si-29, and (SiO)-Si-30, were calculated based on ab initio quantum chemical calculations of the electric dipole moment function and the transition moment. Vibrational anharmonicity and Hermann-Wallis correction factors were also incorporated. From the line strengths at specific temperatures and the known Dunham coefficients, the absorbance spectrum was simulated with best fits giving the averaged SiO concentration in the 400 mm reaction zone of 1.0 x 10(17) molecules/cm(3). Such quantitative measurements demonstrate the power of in situ infrared (IR) spectroscopy combined with quantum chemical calculations. The rapid determination of synthetic calibration datasets for chemometric analysis can thus lead to correlation of gas-phase species concentrations with fiber growth properties and subsequently to real-time process control

Prototype reactor for scale-up of Si-N-O fibre production

A mat of amorphous silicon oxynitride (Si-N-0) can be grown at 1723 K under flowing ammonia on a precursor powder mixture consisting of fine silica, silicon carbide and titanium particles spread on a SiC substrate plate. Single fibers sampled from the mat surface were found to possess outstanding high- performance properties with respect to chemical, mechanical as well as structural stability. The fibers are therefore promising candidates for use as reinforcement in CMC's for high-temperature applications. In the laboratory reactor, however, the production rate is a mere 3 g of fibers per batch run. In order to allow the manufacture of preforms and test bodies, an increase in the production rate to 50g of fibers per batch run was desired. This aim has been achieved by the scale-up of the laboratory furnace to a high-temperature prototype reactor

CVD process for Si-N-O fibre growth controlled by in-situ FTIR spectroscopic monitoring

High strength and high temperature composite materials such as CMCs represent a very promising family of future materials. A high temperature CVD-process has been developed to produce a new type of high-performance amorphous silicon-oxynitride (Si-N-O) fibres. The fibres were grown on a SiC substrate at 1450°C exposing a stoichiometric precursor powder mixture of SiO2 + SiC, doped with 10 wt% Ti powder to flowing NH3. To improve CVD process control an in-situ FTIR monitoring system is in development. For application of a FTIR based monitoring to the fibre growth process a specific optical adaptation has been designed onto the growth reactor. The optical set-up allows an almost simultaneous in-situ measurement of the transmission and emission of the hot gas atmosphere just above the precursor powder mixture. In addition to the decomposition of NH3, different reaction products have been identified, such as CO, HCN and CH4. Gaseous Si-O species could be detected which are responsible for the silicon transport in the gas phase from the solid SiO2 precursor powder to the fibre growth position. The assessment of the SiO bands has been supported by additional experiments which promote the formation of gaseous SiO

NIR diode laser based process control for industrial CVD reactors

The proposed new technical approach for CVD process control is characterised by a "chemistry based" feedback system with in-situ optical data as input information. The selected optical sensors continuously analyse 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 a data basis for process control. Diode laser spectroscopy in the near infra red (NIR-DLS) has been successfully applied for monitoring industrial CVD reactors. This technology has some notable potential advantages for production process applications. For example, the technology is robust and simple to operate, interference between species detection can be reduced, and simultaneous multi-point monitoring is readily achieved. The new process control approach is currently being verified on different industrialised CVD coaters. The paper will present some results of recent process monitoring studies on deposition of SnO2 layers on glass, based on the oxidation of (CH3)2SnCl2, which is used in high volume production for low-E glazings. Kinetic investigations support the empirically determined stiff correlation between gas phase composition and deposition rate

NIR Diode Laser Based Process Control for Industrial CVD Reactors

The proposed new technical approach for CVD process control is characterised by a chemistry based feedback system with in-situ optical data as input information. The selected optical sensors continuously analyse 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 a data basis for process control. Diode laser spectroscopy in the near infra red (NIR-DLS) has been successfully applied for monitoring industrial CVD reactors. This technology has some notable potential advantages for production process applications. For example, the technology is robust and simple to operate, interference between species detection can be reduced, and simultaneous multi-point monitoring is readily achieved . The new process control approach is currently being verified on different industrialised CVD coaters. The paper will present some results of recent process monitoring studies on dep osition of SnO2 layers on glass, based on the oxidation of (CH3)2SnCl2, which is used in high volume production for low-E glazings. Kinetic investigations support the empirically determined stiff correlation between gas phase composition and deposition rate

NIR diode laser based process control for industrial CVD reactors

The proposed new technical approach for CVD process control is characterised by a "chemistry based" feedback system with in-situ optical data as input information. The selected optical sensors continuously analyse 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 a data basis for process control. Diode laser spectroscopy in the near infra red (NIR-DLS) has been successfully applied for monitoring industrial CVD reactors. This technology has some notable potential advantages for production process applications. For example, the technology is robust and simple to operate, interference between species detection can be reduced, and simultaneous multi-point monitoring is readily achieved. The new process control approach is currently being verified on different industrialised CVD coaters. The paper will present some results of recent process monitoring studies on deposition of SnO2 layers on glass, based on the oxidation of (CH3)2SnCl2, which is used in high volume production for low-E glazings. Kinetic investigations support the empirically determined stiff correlation between gas phase composition and deposition rate