[9p-W631-1~11] 3.7 Laser processing

△ [9p-W631-2] Electrode formation at Ni/SiC interface by the introduction of femtosecond-laser-induced modifications

〇(B)Yusaku Mizuo¹, Yuki Fuchikami², Takuro Tomita³, Hiromu Hisazawa³, Tatsuya Okada³ (1.Undergrad. Student, 2.Graduate Student, 3.Tokushima Univ.)

Keywords:silicon carbide, femtosecond laser, I-V characteristic

The objective of the present study was to lower the annealing temperature to form ohmic contacts at the Ni/SiC interface with the aid of femtosecond-laser-induced modifications. Femtosecond laser pulses were irradiated in two areas on the (0001) surface of 4H-SiC. The pulses of 30 nJ were irradiated along lines. A 100-nm-thick Ni film was deposited on the laser-irradiated area by electron beam evaporation. The current-voltage (I-V) characteristics between the Ni electrodes were measured by a 2-probe method. The I-V curves of the present samples were completely different from the Schottky type. And the I-V characteristic was improved with the annealing time to become almost linear (ohmic) after annealing for 18 minutes. The annealing temperature of 773 K in the present study is lower than that of the conventional annealing process for achieving ohmic contacts at the Ni/SiC system by approximately 500 K. This improvement is accounted for by the introduction of femtosecond-laser-induced modifications on the SiC surface which acted to enhance the formation of Ni-silicide at the Ni/SiC interface followed by the diffusion of C atoms towards the surface.