Development of Large Diameter High-Purity Semi-Insulating 4H-SiC Wafers for Microwave Devices

Abstract

The next generation of wireless infrastructure will rely heavily upon wide band gap semiconductors owing to their unique materials properties, including: their large bandgap, high thermal conductivity, and high breakdown field. To facilitate implementation of this next generation, a significant effort is required to make SiC MESFET and GaN HEMT microwave devices more suitable for widespread application. Currently, the interest in high-purity semiinsulating (HPSI) 4H-SiC is critically tied to its influence on microwave devices, whether performance or affordability. To address these issues, we have developed high-purity 3-inch and 100 mm 4H-SiC substrates with low micropipe densities (as low as 1.4 cm -2 in 3-inch and <60 cm -2 in 100 mm) and uniform semi-insulating properties (>10 9 Ωcm) over the full wafer diameter. These wafers possess typical residual shallow level contamination less than 1x10 16 cm -3 (5x10 15 nitrogen and 3x10 15 boron) with best nitrogen values of 3x10 14 . In this paper, we will report on the development of our HPSI growth process focusing on the specific areas of the assessment of semiinsulating character and device applicability.

Bulk and epitaxial growth of silicon carbide

“…More recently, use of intrinsic point defects, which create deep levels, has been investigated, and "highpurity semi-insulating" (HPSI) wafers have been obtained [76,77]. Intrinsic point defects can be introduced by adjusting the growth conditions or by high-energy particle irradiation after growth [78].…”

Vanadium doping using VCl4 source during the chloro-carbon epitaxial growth of 4H-SiC

“…In the high-purity semiinsulating (HPSI) SiC materials grown by high-temperature chemical vapor deposition (HTCVD) [10,11] and PVT [12,13], the compensation of shallow donor and acceptor levels was achieved by intrinsic deep-level defects. However, the exact nature of the intrinsic defects involved in the compensation mechanisms is still under investigation [5,17].…”

“…Main approaches to achieving SI properties in SiC include (1) intentional vanadium (V) doping [3][4][5][6][7] and (2) use of deep levels caused by intrinsic defects [8][9][10][11][12][13]. Other transition metals such as iron (Fe) have also been investigated for producing resistive SiC substrates and epitaxial layers [14,15].…”

EPR andab initiocalculation study on the EI4 center in4H- and6H-SiC

“…In HPSI SiC substrates grown by hightemperature chemical vapor deposition ͑HTCVD͒ ͑Refs. 4-6͒ or by physical vapor deposition 7,8 semi-insulating ͑SI͒ properties have been achieved using intrinsic defects. In those materials, deep acceptor levels of vacancy-related defects can compensate the residual N shallow donors to pin the Fermi level to one of the deep levels and highly resistive materials with typical resistivity in the range of 10 6 -10 10 ⍀ cm can be achieved.…”

“…In those materials, deep acceptor levels of vacancy-related defects can compensate the residual N shallow donors to pin the Fermi level to one of the deep levels and highly resistive materials with typical resistivity in the range of 10 6 -10 10 ⍀ cm can be achieved. [4][5][6][7][8] There are different types of HPSI SiC materials characterized by different activation energies ranging from ϳ0.6 to ϳ1.6 eV. [4][5][6][7][8] It has been shown that carrier compensation processes in HPSI 4H-SiC materials are complicated, involving different defects of which the silicon vacancy ͑V Si ͒, the carbon vacancy ͑V C ͒, the carbon antisite-vacancy pairs ͑C Si V C ͒, and the divacancy ͑V C V Si ͒ are the most prominent ones.…”