High mobility bottom gate InGaZnO thin film transistors with Si O x etch stopper

The authors report on the fabrication of thin film transistors (TFTs), which use an amorphous indium gallium zinc oxide ( a - IGZO ) channel, by rf sputtering at room temperature and for which the channel length and width are patterned by photolithography and dry etching. To prevent plasma damage to the active channel, a 100 - nm -thick Si O x layer deposited by plasma enhanced chemical vapor deposition was adopted as an etch stopper structure. The a - IGZO TFT ( W ∕ L = 10 μ m ∕ 50 μ m ) fabricated on glass exhibited a high field-effect mobility of 35.8 cm 2 ∕ V s , a subthreshold gate swing value of 0.59 V ∕ decade , a thrseshold voltage of 5.9 V , and an I on ∕ off ratio of 4.9 × 10 6 , which is acceptable for use as the switching transistor of an active-matrix TFT backplane.