Temperature, background

The minienvironment approach to contamination control has been increasing in use. A minienvironment is a localized environment created by an enclosure that isolates the product wafer from contamination and people (48). Another approach is using integrated processing, where consecutive processes are linked in a controlled environment (32). Both requite in situ sensors (qv) to measure internal chamber temperatures, background contamination, gas flow rates, pressure changes, and particularly wafer temperature (4). 

Figure 3 is the absorbance spectrum of a sample of the ambient laboratory air drawn into the cell. Here, in accord with the usual procedure, the initially determined spectrum was first corrected for radiation that had reached the detector without having passed through the sample (room temperature background radiation entering the optical path via imperfect optical components and nonoverlap of the source and detector pupils and fields), ratioed against a zero-sample spectrum, and converted to absorbance. Trace (A) shows the spectrum from 3600-600 cm l. The massive absorbances seen here truncated at 1% transmission are due to water vapor and to carbon dioxide. 

By careful optimization of the MAPLE deposition conditions (laser wavelength, repetition rate, solvent type, concentration, temperature, background gas and gas pressure), this process can occur without any significant chemical decomposition. When a substrate is positioned directly in the path of the plume, a coating starts to form from the evaporated organic molecules, while the volatile solvent molecules, which have very low sticking coefficients, are evacuated by the pump in the deposition chamber. 

Fig. 5. Energy dispersive x-ray diffraction pattern ofNO NOs measured at (a) 9.9 GPa, (b) 21.4 GPa and (c) 32.2 GPa and room temperature. Background has been subtracted. The energy calibration was obtained from a gold external standard diffraction pattern and the pattern has been background subtracted. The 20 used was 8.99°. The calculated d-spacings are indicated below each diffraction pattern. The calculated intensity profile for the energy-dispersive x-ray diffraction pattern at 21.4 GPa is shown in the inset, (from Ref. [79])...

Fig. 3.8- Performance of cooled bolometers NEP of carbon, germanium, silicon, and thallium selenide semiconducting bolometers and tin, aluminum and titanium superconducting bolometers. Details in Table 3.3, composite bolometers in Table 8.1 (p. 303), 50% absorption has been assumed for the composite bolometers. The solid line is Coron s [3.42J estimate of the best attainable performance of a Ge bolometer in the absence of higher temperature background radiation...

Test set design should generally allow the introduction of a room-temperature shutter or a chopper blade between the blackbody and the detector. This allows the test set to provide significantly more data with little additional complexity One can measure signal from a hot source (the blackbody), from the room-temperature background, or from the difference between the two. 

As indicated earlier, the performance of most IR detectors is strongly influenced by the background irradiance. For space-based detectors, background photon flux levels of 10 photons/(cm s) are not uncommon this is eight orders of magnitude below an unfiltered, unshielded, room-temperature background. 

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