The AuGe-alloy source and drain (S/D) formed on SiO₂/Si(100) by the lithography process was investigated for the scaling of the organic field-effect transistors (OFETs) with bottom-contact geometry. The S/D was fabricated by the lift-off process utilizing the resist of OFPR. The OFETs with minimum channel length of 2.4 µm was successfully fabricated by the lift-off process. The fabrication yield of Au S/D was 57%, while it was increased to 93% and 100% in case of the Au-1%Ge and Au-7.4%Ge S/D, respectively. Although the mobility of the OFETs with Au-7.4%Ge S/D was decreased to 1.1×10^-3 cm²/(Vs), it was able to be increased to 5.5×10^-2 cm²/(Vs) by the surface cleaning utilizing H₂SO₄/H₂O₂ mixture solution (SPM) and post metallization annealing (PMA) after lift-off process, which was higher than that of OFET with Au S/D.