Latest SiC Epitaxial Layer Growth Results in a High-Throughput 6×150 mm Warm-Wall Planetary Reactor

Abstract

Latest results are presented for SiC-epitaxial growths employing a novel 6x150-mm/10x100-mm Warm-Wall Planetary Vapor-Phase Epitaxial (VPE) Reactor. The increased throughput offered by this reactor and 150-mm diameter wafers, is intended to reduce the cost per unit area for SiC epitaxial layers, increasing the market penetration of already successful commercial SiC Schottky and MOSFET devices [1]. Increased growth rates of 30-40 micron/hr and short <2 hr fixed-cycle times (including rapid heat-up and cool-down ramps), while maintaining desirable epitaxial layer quality were achieved. Increased quantities of 150-mm epitaxial wafers now allow statistical analysis of their epitaxial layer properties. Specular epitaxial layer morphology was obtained, with morphological defect densities <0.4 cm-2, consistent with projected 5x5 mm die yields averaging 93% for Si-face epitaxial layers between 10 and 30 microns thick. Intrawafer thickness and doping uniformity are good, averaging 1.7% and 5.1% respectively. Wafer-to-wafer doping variation has also been significantly reduced from ~12 [5] to <3% s/mean. Initial results for C-face growths show excellent morphology (97%) but poor doping uniformity (~16%). Wafer shape is relatively unchanged by epitaxial growth consistent with good epitaxial temperature uniformity.

Extensive 99% Killer Defect Free 4H-SiC Epitaxial Layer toward High Current Large Chip Devices

“…In this paper, we have demonstrated an extensive 99% defect free epitaxial layer having excellent doping and thickness uniformity simultaneously. BPDs can be almost completely eliminated by a highly efficient BPDs conversion process, resulting in a 99.9% BPD free epitaxial layer as previously reported [2]. In addition, by introducing an improved procedure to reduce other defects in the CVD growth process and furnace, such macro defects also can be significantly suppressed steadily and stably, demonstrating extensive defect free area (DFA) of 99% in a 5 mm x 5 mm block evaluation on a commercially available 150 mm diameter substrate.…”

“…In recent years, the expansion of the wafer size of 4H-SiC substrates has required the enhancement of precisely controlled fabrication processes for large chip dies in order to achieve higher current ratings. The epitaxial layer for the drift region in device structures which is usually grown using CVD method [2], strongly influences device performance, entailing to the elimination of epitaxial defects to produce large chip dies stably. Above all, device killer defects as typified by triangular defects and down-falls, which are considered as almost harmful defects, irrespective of device structures, should be eradicated.…”

Mechanisms of growth and defect properties of epitaxial SiC

“…A similar type of reactor which has a non-actively heated ceiling (the ceiling is heated through radiation from the susceptor) is the planetary warmwall reactor which is, nowadays, by far the most common production tool for thinner layers. 38,39 …”

99.9% BPD Free 4H-SiC Epitaxial Layer with Precisely Controlled Doping upon 3 x 150 mm Hot-Wall CVD

“…SiC power devices such as MOSFETs and SBDs are anticipated to be key devices for power conversion systems [1]. In recent years, the expansion of the wafer size of 4H-SiC substrates has increased the requirements of precisely controlled fabrication processes in terms of device performance stability [2]. Above all, the epitaxial layer for the drift region in device structures which is usually grown by CVD method, strongly influences device characteristics, entailing the excellent thickness and doping uniformity as well as the eradication of epitaxial killer defects and basal plane dislocations (BPDs).…”