Contents I. Introduction
Theoretically, SiC power MOSFETs have lower specific on-resistance than silicon devices of the same blocking voltage due to its higher breakdown field. This has been demonstrated in a number of vertical SiC MOSFETs. Though vertical structures (DMOS, UMOS) are expected to be used for discrete devices for their lower specific on-resistance, lateral power MOSFETs are more attractive for integration in power ICs. 4H-SiC has been recognized as the polytype of choice for making SiC power devices due to its high and isotropic bulk mobility. First, 4H-SiC LDMOSFET demonstrated a high blocking voltage of 2.6 kV and high on-resistance. [1] While a 1000–V 130- lateral reduced surface field (RESURF) MOSFET has been successfully demonstrated in 6H-SiC [2], its 4H-SiC counterpart is more inferior due to low inversion layer mobility [3]. A 730-V 71- 4H-SiC buried-channel lateral MOSFET has also been recently reported [4]. With the significant improvement of the interface of 4H-SiC– by nitric–oxide annealing [5], [6], it is promising to incorporate it into the fabrication of 4H-SiC lateral RESURF MOSFET. (a) Schematic cross section of a lateral two-zone RESURF MOSFET. (b) Photos of fabricated small, circular MOSFET and large, multifinger MOSFET.
