Electrical Characterization of MOS Structures with Deposited Oxides Annealed in N₂O or NO

Abstract

In this work, the electrical characteristics and the reliability of 80nm thick deposited oxides annealed in NO and N2O on the 4H-SiC Si-face for gate oxide application in MOS devices is analyzed by C-V, I-V measurements and by constant current stress. Compared to thermally grown oxides, the deposited oxides annealed in N2O or NO showed improved electrical properties. Dit-values lower than 1011cm-2eV-1 have been achieved for the NO sample. The intrinsic QBD-values of deposited and annealed oxides are one order of magnitudes higher than the highest values reported for thermally grown oxides. Also MOSFETS were fabricated with a channel mobility of 20.05 cm2/Vs for the NO annealed deposited oxide. Furthermore annealing in NO is preferred to annealing in N2O regarding µFE- and QBD-values.

SiC Epi-Channel Lateral MOSFETs

“…Although this value doesn't seem too impressive, it is worth noting that this value is obtained with the gate oxide grown by thermal Materials Science Forum Vols. 778-780 oxidation in N 2 O ambient, which is not a very effective way to passivate/reduce the traps of SiC/oxide interface, and rarely showed mobilities larger than 10 cm 2 /Vs [6]. When compared with the first control sample type 1, the mobility has been greatly improved.…”

Investigation of nitridation and oxidation reactions at SiC/SiO2interfaces in NO annealing and modeling of their quantitative impacts on mobility of SiC MOSFETs

“…12) As a result, they found that the ratio of oxidation is higher in N 2 O annealing than in NO annealing, leading to the lower mobility of the N 2 O-annealed MOSFETs. 22,23) Thus, their results strongly suggest that the oxidation reaction during NO annealing or N 2 O annealing causes the degradation of the channel mobility.…”

Comparative Study of 4H-SiC DMOSFETs with N₂O Thermal Oxide and Deposit Oxide with Post Oxidation Anneal

“…Carbon clusters and interstitials are considered as electron traps and centers of Coulomb scattering [1][2][3]. One of the strategies to improve the channel mobility of SiC MOSFETs is to introduce some species, such as nitrogen of N 2 O, NO or phosphorus of POCl 3 , to passivate the problematic interfacial carbon clusters during oxidation or through post oxidation annealing [4,5]. In this work, two kinds of oxidation processes were used to fabricate gate oxides and the characteristics of DMOSFETs and the oxide reliability were studied.…”