3. Dielectric breakdown field

A capability to sustain a high electric field without any failure is known a dielectric strength. The dielectric breakdown (EBRdz%/z0\$!z)4%)1)z(%)%0z+"z!(!0.%z"%!( z0\$0z %!(!0.%z\*z0+(!.¥ ate under the influence of high supply voltage. In general dielectric field can be defined as

$$E\_{\rm BR} = \frac{V\_{\rm BR}}{d} \tag{1}$$

been implemented such as dry oxidation, wet oxidation, chemical vapour deposition (CVD), and pyrogenic oxidation in order to achieve the most suitable process to realize the SiC-

plementation of SiO2/SiC interface, in the fabrication of MOS transistor. The intricacy of SiO2/SiC interface, in comparison to the Si based structure, causes severe problems even 0\$+1#\$z0\$!z)+%(%05z%/z.! 1! z5zHMz+"z0\$!z0\$!+.!0%(z2(1!^z\$!z!/0z+4% !z-1(%05z%/z+¥ tained by the means of dry oxidation process performed at temperatures more than 1100 °C. The growth mechanism of oxide on Si substrate is limited by the diffusion of oxygen at SiO2u%z%\*0!."!^z+3!2!.\_z%\*z/!z+"z%z/5/0!)z 0\$%/z %""1/%+\*z,.+!//z+1\*0!\*\*!/z %""%¥ 1(0%!/z!1/!z+"z 0\$!z,.!/!\*!z+"zz0+)/\_z3\$%\$z.!z,.!/!\*0z(+\*#z3%0\$z%z0+)/^z\$!z¥ tual growth mechanism of SiO2 on SiC surface is not well understood yet. Hypotheses ,.+,+/!z)%#.0%+\*z+"z".!!zz0+)/z%\*z()+/0z!2!.5z %.!0%+\*^z\$!z)+/0z,.+(!z%/z+10w %""1¥ sion of CO2 or CO through the grown silicon oxide but also formation of carbon clusters at the SiO2/SiC interface and even diffusion of C into bulk SiC are possible. (Song Y., 2004) and his team have proposed a model of the thermal oxide growth on hexagonal SiC in the frame of deal and grove model. The work assumes two competitive processes influencing SiO2z"+.¥ mation, one is the in-diffusion of oxygen towards the interface and the other one is the outdiffusion of CO. However, by experimental data one cannot prove that some of the carbon atoms do not stay at the interface and form very stable carbon cluster (Kobayashi H. 2003 and Wang S., 2001). Further investigation was also carried out by of thermal oxidation and re-oxidation with different by using different oxygen isotopes, which seems to confirm that unknown carbon structures exist at the interface (Cantin, J.L.2004). Atomic layer deposition (ALD) has proved a potential method for materials deposition (Leskela M., 2002). Using this technique very well controlled growth is possible, almost atomic layer by atomic layer, of 0\$!z !/%.! z /,!%!/z ".+)z #/!+1/z ,.!1./+./^z \*(1'%(5\_z 2!.5z "!3z ,1(%0%+\*/z .!,+.0z !""%¥ cient SiO2 deposition using ALD technique on 4H-SiC substrate (Perez I., 2000). (Amy F., 1999dz\* z\$%/z+z3+.'!.z\$/z !,+/%0! z0\$%\*z%z(5!.z+\*z%z/1."!z\* z(0!.z0\$!.)(z+4% ¥ 0%+\*z+"z0\$!z%z(5!.z3/z,!."+.)! ^zw.5z,\$+0+!(!0.+\*z/,!0.+/+,5zcdz3/z"1.0\$!.z!)¥ ployed to study of such an attempt on 6H-SiC and the material formed by overplayed +4% 0%+\*z/\$+3/z(!//z%z\* zz.!(0! z/,!%!/z%\*z+),.%/+\*z3%0\$z 0\$!.)((5z+4% %6! z/)¥ ples. This method shows a less complex oxidation mechanism by comparing the case. (2¥ nas'ev V.V., 1997) and his team has performed verity of experiment to characterize the interface properties of SiO2/SiC. Finally, this research group was investigated the basic mechanism of interface states distribution for SiC system. In such a system the interface traps density may arise from three main sources i.e. graphite-like carbon, carbon clusters and oxide traps. However, a similar type of paper was again presented by the same author in 2005 (Avanas'ev V.V., 1997). He concluded that that during 8 years of intensive studies this complex problem of oxidation and interface properties is still unsolved. At present time also Si and SiO2 are very useful system, but electric field strength in SiC can reach the values 10 times higher than those observed in case of Si. In case of SiC as base material the potential barrier height between SiO2 and SiC is even smaller, indicates toward a serious problem. Moreover, SiC based structures can operate at much more higher temperature than that of Si

d^z\$%/z+\* %0%+\*z,.+ 1! zz(+0z+"z!""+.0z%\*0+z0\$!z%)¥

http://dx.doi.org/10.5772/52553

211

Materials and Processing for Gate Dielectrics on Silicon Carbide (SiC) Surface

based MOS structures (Gupta S.K, 2011a

Where VBR is the breakdown voltage and d is the dielectric thickness. Dielectric strength is 0\$!z%\*\$!.!\*0z,\$!\*+)!\*+\*z+"z %!(!0.%z)0!.%(z\* z%0z)%\*(5z !,!\* /z+\*z/0.101.(z,.+,!.¥ ties. In the development of dielectric material, growth condition (material thickness, voltage .),z /,!! \_z .%0%(z 211)\_z #.+30\$u !,+/%0%+\*z .0!dz \* z !\*2%.+\*)!\*0(z +\* %0%+\*z c!)¥ perature, humidity) are very important.
