Process to manufacture thin film transistors by photolithography based of chalcogenide semiconductors deposited by CBD

Abstract

Chalcogenide semiconductors and transition metal oxides present a wide and interesting range of physical and chemical properties were the magnetic, electrical, optical, catalytic and energy harvesting ones stand out. These materials have been used in the development of devices such as flat screen TVs, smart gaseous windows, optical write-read-erase devices, sensors (gas, humidity and temperature) and for field emission and solar cells and Thin Film Transistors. This study reports the optimization of the gate dielectric etching process and the active semiconductor layer for the manufacture of a P-type thin film transistor (TFT) by photolithography. The manufacture of TFT uses Hafnium Oxide (HfO2) as gate dielectric deposited by Atomic Layer Deposition (ALD), Copper Sulfide (CuS) as P-type active layer deposited by Chemical Bath Deposition (CBD) and Chromium (Cr) as gate metal (G), source metal (S) and drain metal (D) deposited by sputtering in a gate-bottom, top-contact (BGTC) structure. Hydrochloric acid (HCl) was used as an attacker of active layer of CuS. The etching of the dielectric layer was performed with optimized photolithography and negative photoresin was deposited before depositing the HfO2, avoiding the use of Buffered Oxide Etch (BOE). The electrical characterization of p-type TFT shows that the optimized manufacturing process is successful and scalable to any chalcogenide as active layer.