Power SiC MOSFETs

One of the most important issues preventing commercialization of power SiC MOSFETs so far is MOS channel resistance that results from the extremely low inversion channel mobility in 4H-SiC [19]. This problem may become especially significant in the case of 4H-SiC UMOSFETs, where the oxide-semiconductor interface is severely damaged by plasma etch when the trenches are formed. In general, there are two major approaches to minimize the channel component of on-resistance ... 

In this chapter, we discussed different approaches used for the design and fabrication of power SiC MOSFETs, including a review of the various structures (UMOS, DMOS, and LDMOS) and process challenges associated with each structure. 

However, after the first years of great expectations supported by early impressive results reported by Palmour et al. in 1994 [5], it became clear that initial predictions of a revolutionary improvement in power switching by employing vertical SiC MOSFETs are difficult to accomplish due to multiple reasons. In particular, a critical analysis of performance advantages and limitations of 4H-SiC power UMOSFET structure has been made by Agarwal et al. in 1996 [6]. The main issues raised in this work were ... 

Diamond and Refractory Ceramic Semiconductors. Ceramic thin films of diamond, sihcon carbide, and other refractory semiconductors (qv), eg, cubic BN and BP and GaN and GaAlN, are of interest because of the special combination of thermal, mechanical, and electronic properties (see Refractories). The majority of the research effort has focused on SiC and diamond, because these materials have much greater figures of merit for transistor power and frequency performance than Si, GaAs, and InP (13). Compared to typical semiconductors such as Si and GaAs, these materials also offer the possibiUty of device operation at considerably higher temperatures. For example, operation of a siUcon carbide MOSFET at temperatures above 900 K has been demonstrated. These devices have not yet been commercialized, however. 

Figure 3.12 Current and voltage for MOSFETs operating in the power factor correction circuit using (a) Si diodes and snubber circuit and (b) SiC diodes only. (From [14]. 2002 Cree, Inc. Reprinted with permission.)...

Peters, D., et ah, 4H-SiC Power MOSFET Blocking 1200V with a Gate Technology Compatible with Industrial Applications, European Conference on Silicon Carbide and Related Materials, September 1-5, 2002. 

Shenoy, J. N., J. A. Cooper, Jr., and M. R. Melloch, High-Voltage Double-Implanted Power MOSFETs in 6H-SiC, IEEE Electron Device Letters, Vol. 18, Issue 3, March 1997, pp. 93-95. 

Agarwal, A., et al., Large Area 4H-SiC Power MOSFETs, Proc. of the 13th Inti. Symposium on Power Semiconductor Devices and ICs, June 4-7, 2001, pp. 183-186. 

FIGURE 10 Current-voltage characteristics of 6H-SiC n-channel vertical power MOSFET at room... 

Figure 15 The Baliga pair power switch configuration utilizing a high-voltage SiC MESFET and a low-voltage silicon MOSFET.

---