Thermal degradation of Au/Ni2Si/n-SiC ohmic contacts under different conditions

High-Temperature Electrical and Thermal Aging Performance and Application Considerations for SiC Power DMOSFETs

“…This non-linear or rectifying type output characteristic has been demonstrated before for nickel silicide based 4H-SiC ohmic contacts aged in air for 150 h at 400 °C [6]. In that case, the author attributed this to degradation of the ohmic contact itself.…”

“…The degradation mechanisms of ohmic contacts for SiC at high temperatures was shown by [4], and can be summarized as voiding due to dissimilar diffusion rates of adjacent metal layers. In the case of operation in air or oxygen containing environments, various metal stack and ceramic oxygen diffusion barriers have been demonstrated on top of the ohmic contacts to have high performance at extremely high temperatures from 450 °C to 750 °C [5][6][7][8][9][10]. It is not known whether such features have been incorporated into commercially-available devices, as such detail is generally retained as commercial secrets by the device manufacturers.…”

Amorphous Ni–Zr layer applied for microstructure improvement of Ni-based ohmic contacts to SiC

“…Aiming to improve the microstructure of nickel-based ohmic contacts, an initial multilayer structure containing nickel and silicon can be used [17][18][19][20][21]. In such a case, Ni atoms react mainly with deposited Si instead of SiC substrate.…”

Characteristics and aging of SiC MOSFETs operated at very high temperatures

“…Such complex interactions have been demonstrated at above 450°C, and barrier layer solutions have been proposed both for the gate structures, to slow down the exchange of Si and Al atoms, and the voiding and delamination of ohmic contacts [6]. Thermal aging of n-type ohmic contact structures has also been demonstrated recently, and shown to produce a rectifying type response in the forward I-V characteristic after hundreds of hours at 400°C in air [7]. Operation of SiC devices in air is of interest because encapsulation and molding compounds suitable for long term operation above 250°C do not exist currently [8,9].…”