Reduction of interface-state density in 4H–SiC n-type metal–oxide–semiconductor structures using high-temperature hydrogen annealing

Abstract

The effects of hydrogen annealing on capacitance–voltage (C–V) characteristics and interface-state density (Dit) of 4H–SiC metal–oxide–semiconductor (MOS) structures have been investigated. The Dit was reduced to as low as 1×1011 eV−1 cm−2 at Ec−E=0.6 eV using hydrogen annealing above 800 °C, where Ec−E is the energy level from the conduction-band edge. Secondary ion mass spectroscopy and Dit analysis revealed that Dit decreased with the increase of hydrogen concentration accumulated at the SiO2/4H–SiC interface. The interface states at SiO2/4H–SiC are thought to be originated from the dangling bonds of C atoms as well as Si atoms, because Dit decreases as the hydrogen annealing temperature increases and saturates around 800 °C. This high-temperature hydrogen annealing is useful for accumulation-type SiC metal–oxide–semiconductor field-effect transistors, which have n-type MOS structures to reduce the Dit.

Hydrogen Incorporation Dependence on the Thermal Growth Route in Dielectric/SiC Structures

“…• C. 12,13,18 On the other hand, the quality of the Pt electrode degrades at anneal temperatures greater than 600…”

“…Silicon oxynitride film growth in NO (NO-route) or NOannealing of Si 18 O 2 /SiC (O 2 /NO-route) were performed at 1250 o C for 2 h at a NO flow rate of 0.1 SLM. Concerning H 2 annealing temperature, previous works reported improvement in D it and channel mobility for 4H-SiC (0001) MOSFETs using POA in hydrogen at temperatures ≥ 800• C. 12,13,18 On the other hand, the quality of the Pt electrode degrades at anneal temperatures greater than 600• C. …”

“…4,8 The effect of the incorporation of N was related to both the removal and the passivation of residual C in the dielectric/SiC interface region. [9][10][11] The use of POA in H 2 also led to reduction in D it below the conduction band for n-type 4H-SiC (0001) MOS structures 12 and improve the channel mobility of 4H-SiC (0001) MOSFETs. 13 Moreover, combining POAs in NO and in H 2 using platinum (Pt) as the electrode metal caused a complementary reduction in D it 10,14 and enhanced field-effect mobility in 4H-SiC (0001) MOSFETs 15 compared with only NO or only H 2 annealings.…”

Characterization and physical modeling of MOS capacitors in epitaxial graphene monolayers and bilayers on 6H-SiC

“…39,40 From Fig. 2, the monolayer material exhibits the larger swing in Fermi energy with ϵ f ∈ [−0.32, 0.28eV] over the applied bias range.…”

Comment on “Reduction of interface-state density in 4H–SiC n-type metal–oxide–semiconductor structures using high-temperature hydrogen annealing” [Appl. Phys. Lett. 76, 1585 (2000)]

“…Phys. Lett In a recent letter, Fukuda et al 1 reported the interface state density reduction in n-type 4H-SiC/SiO 2 structures subsequent to annealing in H 2 at temperatures TϾ400°C. This led the authors to the conclusion that the observed interface defects ''...originated from the dangling-bonds of C atoms as well as Si atoms...''.…”