Bulk Growth of SiC

In 1978, Tairov and Tsvetkov [24] reported a sublimation technique to produce SiC boules for device application. They produced an 8 mm diameter by 8 mm long boule of SiC on a seed crystal placed within a graphite crucible. In a further study, growth of SiC boules up to 14 mm diameter and 18 mm in length were obtained [15]. 

Transport mechanisms in sublimation growth are complicated. Growth rate increases with increasing source temperature, increasing source to seed distance, decreasing pressure, and decreasing crystal-source distance [19,20,27-33]. 

FIGURE 1 Sublimation growth crucibles (a) single-wall graphite type and (b) double-wall type. 

Doping is an important issue for bulk growth. For n-type doping nitrogen is used while for p-type doping A1 is used. Special care must be taken in Al-doping [34,35]. 

Most of the reports described above involve 6H-SiC bulk growth on 6H-SiC seed substrates. Yoo et al [46] used 3C-SiC(100) as the substrate for 6H-SiC bulk growth and found 6H-SiC(0114) bulk material was produced. They reported crystals with diameters of 15 mm and 6 mm long. By using different planes of 6H-SiC, polytype control will be easily achieved. 

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Y. Shishkin and O. Kordina, Bulk growth of 6H-SiC on non-basal quasi-polar surfaces,/. Cryst. Growth, 291, 317-319 (2006). 

Bulk SiC substrates made by the Acheson method or the Lely method have been used as the substrates for growth of a-SiC. Recently, SiC wafers sliced from an SiC ingot grown by the modified Lely method have been used. Usually, ((X)01) Si or ((X)01) C surfaces are used. Here, homoepitaxial growth of SiC by CVD using an SiH4-C3Hg-H2 reaction gas system is illustrated... 

S. G. Mueller, R. Eckstein, D. Hofmann, L. Kadinski, P. Kaufmann, M. Koelbl, E. Schmitt. Modelling of the PVT-SiC bulk growth process taking into account global heat transfer, mass transport and heat of crystal-Uzation and results on its experimental verification. Mater Sci Eorum 0 51, 1998. 

Thermal oxidation of the two most common forms of single-crystal silicon carbide with potential for semiconductor electronics applications is discussed 3C-SiC formed by heteroepitaxial growth by chemical vapour deposition on silicon, and 6H-SiC wafers grown in bulk by vacuum sublimation or the Lely method. SiC is also an important ceramic ana abrasive that exists in many different forms. Its oxidation has been studied under a wide variety of conditions. Thermal oxidation of SiC for semiconductor electronic applications is discussed in the following section. Insulating layers on SiC, other than thermal oxide, are discussed in Section C, and the electrical properties of the thermal oxide and metal-oxide-semiconductor capacitors formed on SiC are discussed in Section D. 

Growth from the vapor is the preferred phase transition for the production of thin epitaxial layers, while growth of bulk crystals from the vapor is rather the exception, only applied if unavoidable. An example is the growth of semiconductor-grade Sic by the so-called modified Lely method (MLM), a sublimation technique. The physical reason for the avoidance of vapor growth techniques for bulk crystals is the huge difference in the particle densities between the two states of aggregation. 

On the other hand, bulk crystals of 4H-SiC and 6H-SiC are made by a physical vapor transport (seeded sublimation growth) technique known as the modified-Lely method [32]. High-quality bulk materials (threading dislocation... 

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