Chemical vapor deposition of Si in a lamp-heated single-wafer reactor is studied by monitoring the growth rate of films deposited on bare Si, silicon-on-insulator ͑SOI͒, and oxidized Si wafers. The growth rate is consistently higher for deposition of polycrystalline Si than for epitaxy of Si, due to different kinetics dictating the two depositions. Epitaxy of Si on SOI shows a higher overall growth rate than on bare Si. Likewise, deposition of polycrystalline Si on oxidized Si wafer with a 4000 Å thick oxide has a higher growth rate than on that with 15 Å oxide. These are attributed to surface emissivity variation during Si deposition. The difference in kinetics plays a more dominant role than the surface emissivity variation in affecting the growth rate for the depositions studied.Chemical vapor deposition ͑CVD͒ of epitaxial Si ͑epi-Si͒ and that of polycrystalline Si ͑poly-Si͒ are characterized with different apparent activation energies in the surface reaction limited regime. 1-5 In our recent study of CVD Si at 600-750°C and 20-80 Torr in a lamp-heated single-wafer reactor, 5 the apparent activation energy for epi-Si is 2.1 eV and that for poly-Si 1.6 eV, in agreement with earlier published results. 1,3,6 Under these deposition conditions, first-order reaction kinetics was found for the ͑average͒ growth rate of epi-Si as well as for poly-Si with respect to the partial pressures of SiH 4 . However, the ͑average͒ growth rate depended more strongly on the partial pressure of H 2 for epi-Si compared to poly-Si. These differences in growth kinetics were attributed to a higher H surface coverage for epi-Si than for poly-Si. Hence the growth rate of epi-Si is limited by H 2 desorption whereas the growth rate of poly-Si is limited by the balance between the SiH 4 adsorption and the H 2 desorption. 5 As a result, an appreciable difference in thickness of the two types of Si layers is observed under identical deposition conditions. 5 Since the susceptor for bedding the Si wafer is heated by lamp radiation, variation of wafer surface emissivity during Si deposition leading to wafer temperature alternation could also result in different growth rates for epi-Si on bare Si substrates and poly-Si on oxidized Si wafers. [7][8][9] The purpose of the present study is to identify the dominant effect on growth rate, i.e., deposition kinetics vs. wafer surface emissivity.The single-wafer reactor used in this study was a commercial ASM Epsilon-2000 system whose cross section is shown schematically in Fig. 1. The whole graphite susceptor of 240 ϫ 280 mm size is coated with SiC to prevent contamination. It is heated by two tungsten-halogen lamp-banks above and below together with four lamps ͑not shown͒ located under the susceptor and centered around the rotating axis. A part of the susceptor is set to rotation to improve thickness uniformity over a wafer. The susceptor temperature is measured with three thermocouples placed in the surrounding fixed part ͑front, rear, and side͒ and one encapsulated in the middle of the rotating part. ...
In this paper we present the design, fabrication and characterization of arrays of boron doped polycrystalline silicon bolometers. The bolometer arrays have been fabricated using CMOS compatible wafer-level transfer bonding. The transfer bonding technique allows the bolometer materials to be deposited and optimized on a separate substrate and then, in a subsequent integration step to be transferred to the read-out integrated circuit (ROIC) wafer. Transfer bonding allows thermal infrared detectors with crystalline and/or high temperature deposited, high performance temperature sensing materials to be integrated on CMOS based ROICs. Uncooled infrared bolometer arrays with 18x18 pixels and with 320x240 pixels have been fabricated on silicon substrates. Individual pixels of the arrays can be addressed for characterization purposes. The resistance of the bolometers has been measured to be in the 50 kW range and the temperature coefficient of resistance (TCR) of the bolometer has been measured to be -0.52 %/K. The pixel structure is designed as a resonant absorbing cavity, with expected absorbance above 90%, in the wavelength interval of 8 to 12 mm. The measured results are in good agreement with the predicted absorbance values.
Articles you may be interested inPhysics and chemistry of hot-wire chemical vapor deposition from silane: Measuring and modeling the silicon epitaxy deposition rate
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.