Thin film transistor and manufacturing method, array substrate and display device thereof

The invention provides a thin film transistor and a manufacturing method, an array substrate and a display device thereof and belongs to the technical field of thin film transistors. The manufacturing method of the thin film transistor comprises the steps that after a semi-conductor layer of the thin film transistor is formed, and a conductive layer not capable of reacting with acid solutions is adopted to form protective layers on the semi-conductor layer; a source electrode and a leakage electrode of the thin film transistor are formed in the protective layer; dry etching is used for removing the protective layers on a gap between the source electrode and the leakage electrode and an area corresponding to the semi-conductor layer, and the semi-conductor layer of the area is exposed. According to the technical scheme of the thin film transistor and the manufacturing method, the array substrate and the display device thereof, an oxide semi-conductor of the Oxide thin film transistor can be well protected, and the picture composition technology is reduced by one time than an existing ESL method; compared with an existing Oxide thin film transistor of an ESL structure, the channel size can be smaller, and the improvement of the aperture ratio of the array substrate of the Oxide thin film transistor and application in high PPI products are facilitated.