Effects of Rapid Thermal Annealing on Ar Inductively Coupled Plasma-Treated n-Type 4H-SiC Schottky and Ohmic Contacts

The effects of Ar inductively coupled plasma (ICP) treatment followed by a 600 °C-1000 °C rapid thermal annealing (RTA) on the n-type 4H-silicon carbide (SiC) Schottky-barrier diodes and n
⁺
-implanted ohmic contacts were investigated. The ICP treatment created a 3-nm-thick, sp
²
-C-rich, and amorphous layer at the SiC surface. The RTA repaired the bombardment-induced damages before metal deposition to avoid current degradation. This ICP + RTA-treated surface strongly pinned the Schottky-barrier height (SBH) at a minimum of 0.88 eV. In theory, the low SBH is beneficial to decrease the specific contact resistance (ρ
_C
). ρ
_C
of the ICP + RTA-treated Ti ohmic contacts decreased to lower than 10
^-5
Ω·cm
²
after 400 °C post-metal deposition annealing (PMDA). However, the additional O atoms, fixed in the amorphous layer by RTA, affected the ρ
_C
reduction. Fortunately, due to the chemical affinity for O of Ti, the in-diffused Ti could contend for the O atoms against the Si-O bonds during the PMDA. Therefore, the oxidized barricade was decomposed gradually, leading to the lowest ρ
_C
, 1.3×10
^-6
Ω·cm
²
, after 600 °C PMDA. The lowest ρ
_C
is 25× and 8× lower than that of the Ni silicide and the nontreated Ti contacts, respectively, at the same doping concentration.