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Sic Thin Film Materials In High Temperature Sensor Applications

Posted on:2001-01-07Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y M LeiFull Text:PDF
GTID:1118360002450790Subject:Microelectronics and Solid State Electronics
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YOngming Lei (MicroeIeCtronics and Solid State EIeCtronics)Advisort Prof6ssor S.C. Zou & Professor YH. YuMonocrystalline silicon is the most important material for manufacturing ofmicroelectronic devices. However silicon has several disadvantages as a maorelectronic material f (i) relatively small bandgaP of about only l. leV (ii) bandgaP ofsilicon is indirect; (iii) bandgap of silicon is not adjustable by alloying, (iv) chemicalstability is rather poor Thus the aPplication of silicon devices to such areas is limited fhigh temPerature, oPtoelectronic applications, and corrosive environments.Silicon Carbide has attraCted intensive research effbrts since its exce1lentphysical properties fOr aPplication in high temPerature, high powee high frequency,high erosive, and high irradiative conditions. Compared with Si's sma1l band gaP ofl. l eV SiC has a much wider band gaP of 2.3eV~3.4eV depending on the variation ofpolytypes. This make SiC become intrinsic only after reaching temPeratures as highas l200'C, while Si (with a doping concentration of l0"cm-') becomes intrinsic atonly about 550'C. As a result, silicon based devices can only operate at junctiontemPeratres up to about l50'C, and SiC devices can operae to temPeratUres of atleast 600~700'C.In this thesis, we stUdied the SiC fi1ms deposited on silicon and SOI substrates byreactive DC magnetron sputtering. A four-inches silicon target was sputtered in aAICH. mixed atmosphere to dePOsit films onto a substrate of tWo inches heated totemPeratures up to 900'C. Compositional studies, including AES, rrS, RBS andNBS studies show that under appropriate conditions, the prepared SiC films arestoichiometric Wth uniform comPositional distribution throughout the film thickness.Magnified AES peaks of C KW and Si LW also show similar peak shapes as thoseof SiC reported in literature, indicating the fOrmation of Si-C bond. Non-RutherfordBackscattering stUdied were carried out to analysis the concentration of oxygen andcarbon in the fiIms, which is difficult to deteCt using RBS. The results of N'BS werequite close to those of AES studies, agreeing on that the films were uniform incomposition and that Stoichiometric SiC films were successful]y prepared.The crystalline structure of the dePosited fiIms was characterized using ro,GA-W, cross sectional TEM, and planar TEM. ro patterns show only one SiCpeak near 35.6', corresponding to 3C-SiC(l11) crystalline p1ane diffiaction. Therealso exists a PcH4 range in Which the ro peak strength of the films was highest. Inaddition, fi1ms prepared in this range were near stoichiometric. Glancing angle rorevealed more 3C-SiC peaks in the diffraCtion patterns. In these patterns one can find3C-SiC (ll l) (220) (3ll) peaks, indicating the crystal1ine phase in the films werecomposed of 3C-SiC, not any other polytypes of SiC. ro studies also lead to theconclusion that higher temPerature (900'C vs. 850'C) could result in better crystallinequalities (larger crystallites).Infrared refleCtance speetra in the range of 400cm-'-000cof' were emPloyed toinvestigate the crystalline stnJctur, strUrmral dimension, stnJCtUral defects of theSiC/Si and SiCOI structures, wt the help of effective medium aPproaches androutine transfer matrix method. The saS of SiC were featured by a restsrahlen peakaround 800cm-'~l000cm-'. The exPerimental spectra can be best fitted by adjustingthe struCtural parameters and the volume fraction of crystalline phases. The resultsshow that nyS is a suitable method for deteCtion of the quaIity of the SiC/Si andSiCOI materials systems.NirSiC contact and its anneaJing behavior were studied by RutheffordBackscattering. The result shows tha 300'C 30min annealing caused no obviousdiffesion, while 500'C 30min annealing caused the formation of a diffose profile withan outer layer richer in nickeI folloWed by an inner layer richer in silicon.We've also studied the ion beam etching of the SiC films p...
Keywords/Search Tags:Applications
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