Insight into enhanced field-effect mobility of 4H-SiC MOSFET with Ba incorporation studied by Hall effect measurements

Abstract

Improved performance in 4H-SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) by incorporating Ba into insulator/SiC interfaces was investigated by using a combination of the Hall effect and split capacitance-voltage measurements. It was found that a moderate annealing temperature causes negligible metal-enhanced oxidation, which is rather beneficial for increments in field-effect mobility (μFE) of the FETs together with suppressed surface roughness of the gate oxides. The combined method revealed that, while severe μFE degradation in SiC-MOSFETs is caused by a reduction of effective mobile carriers due to carrier trapping at the SiO2/SiC interfaces, Ba incorporation into the interface significantly increases mobile carrier density with greater impact than the widely-used nitrided interfaces.

Defect engineering in SiC technology for high-voltage power devices

“…273) Physical analyses also have revealed that a tiny amount of Ba atoms that become segregated at the SiO 2 /SiC interface (∼10 14 cm −2 ) are responsible for the MEO reaction and that continuous and steady MEO proceeds at moderate temperatures over 800 °C. [274][275][276] Interestingly, low-temperature annealing at 750 °C reduced D it and enhanced μ FE without any oxide growth (MEO). 276) Unfortunately, despite these impressive features for modification of the SiO 2 /SiC interface, Ba incorporation has drawbacks in terms of a non-uniform Ba-MEO reaction and degraded insulating properties.…”

“…[274][275][276] Interestingly, low-temperature annealing at 750 °C reduced D it and enhanced μ FE without any oxide growth (MEO). 276) Unfortunately, despite these impressive features for modification of the SiO 2 /SiC interface, Ba incorporation has drawbacks in terms of a non-uniform Ba-MEO reaction and degraded insulating properties. 274,275) Non-uniform SiC oxidation leads to significant roughening of the oxide surface and fluctuation of the gate oxide thickness, but this harmful impact can be mitigated by using a thick SiO 2 capping layer and by optimizing the process conditions.…”

Formation of high-quality SiC(0001)/SiO2 structures by excluding oxidation process with H2 etching before SiO2 deposition and high-temperature N2 annealing

“…Various studies have been conducted to achieve high channel mobility. [20][21][22][23][24][25] Several passivation methods have achieved high channel mobility (∼70-100 cm 2 V −1 s −1 ) (e.g. sodium enhanced oxidation 26,27) and annealing in phosphoryl chloride (POCl 3 ) ambient 28,29) ).…”

Mobility improvement of 4H-SiC (0001) MOSFETs by a three-step process of H2 etching, SiO2 deposition, and interface nitridation

“…nitrogen (N), [7][8][9][10][11][12][13][14] hydrogen (H), 15,16) phosphorous (P), 17,18) and boron (B) 19) ], (2) metal-enhanced oxidation [e.g. sodium (Na) 20,21) and barium (Ba) [22][23][24] ], and (3) the use of Al-based high-k dielectrics (e.g. Al 2 O 3 , [25][26][27] and AlON 28) ).…”