Behavior of Particles in the Growth Reactor and their Effect on Silicon Carbide Epitaxial Growth

Abstract

Formation of particles and their effect on SiC epitaxial growth in the CVD reactor is investigated. Particle induced defects in the epilayer at different gas decomposition conditions are discussed. A higher number of pits with larger diameters are observed in the epilayer for conditions where gases decompose later in the gas injector tube (i.e. nearer to the substrate). On the other hand, the number and size of these pits reduce for the condition where gas decomposes earlier in the tube. To investigate the effect of particles during the growth, various particles with different size, shape and compositions are intentionally placed on the substrate surface before epitaxial films are grown. Samples are mapped and compared at similar locations in the pre-growth, post growth and post-etch (by molten KOH) conditions. It is found that the nature of particle induced defects depends primarily on size and shape of particles.

Elimination of silicon gas phase nucleation using tetrafluorosilane (SiF4) precursor for high quality thick silicon carbide (SiC) homoepitaxy

“…A split gas delivery tube system (gas injector made of SiC coated high purity graphite) was used to visualize parasitic deposition in the tube 2. This design is an effective tool to identify the location at which the gases start decomposing in the injector tube by the observation of parasitic deposition.…”

“…Moreover, liquid aerosol particles adhere to the various reactor parts (parasitic deposition), and contribute to their severe degradation during epitaxial growth. These parasitic depositions are generally loosely bound, and can be carried to the growth surface during growth as particulates, resulting in degradation of crystal quality by introducing defects in the growing epitaxial layers 2. The aforesaid condition is specifically severe at higher precursor gas flow rates or in long duration growth required to achieve high quality thick epitaxy since parasitic deposition and related particulate formation are also increased at these growth conditions.…”

“…Silane is commonly known to cause silicon supersaturation, limiting high growth rates 3–5. Using silane, gas decomposition and parasitic deposition start very early in the gas delivery system and impede achieving good growth by impinging particulates to the growth surface 2, 6, 7. In spite of the above limitations, high growth rate (growth rates of 32 µm h −1 8, 50 µm h −1 9 and even 250 µm h −1 10), good quality (good crystallinity and surface morphology), thick epitaxy has been reported using silane.…”

Trade-Off between Parasitic Deposition and SiC Homoepitaxial Growth Rate Using Halogenated Si-Precursors

“…These parasitic particulates have the potential to come loose and deposit on the SiC growth surface, leading to defects such as pits, stacking faults and screw dislocations, in addition to severe degradation of the surface morphology. 12 ) unless CC License in place (see abstract Therefore, it appears that the strong Si-F bonds in TFS would preclude SiC epitaxial growth since reactive Si containing free radicals with dangling bonds are assumed to be absent in the gas stream. Our initial experiments have shown this to be partially true, as when a mixture consisting only of TFS and hydrogen is introduced into the growth reactor, parasitic deposition of elemental Si in the gas injector wall and on the SiC substrate is completely suppressed (Fig.…”

“…[6][7][8][9][10][11][12][13][14][15][16][17] The influence of defects on device performance is yet to be comprehensively understood, such as threading dislocations, 7-9 basal plane dislocations, 10,11 particulates, 12 in-grown stacking faults 13,14 and other morphological defects, [15][16][17] some of which may be inherited from the SiC substrate. 18 These defects constitute the major bottleneck in the reliability of systems that use SiC power devices, and thus necessitate the development of an optimized epitaxial growth process, the subject of this paper.…”