Method of manufacturing array substrate and method of manufacturing display device

A method of manufacturing an array substrate, comprising steps of:

• forming a planarization layer above a base substrate;
• forming an electrode layer above the planarization layer;
• forming a metal functional layer above the electrode layer;
• patterning the metal functional layer by using a multi-greyscale mask layer as a mask;
• forming an insulating protection layer on a portion of the electrode layer not being covered by the patterned metal functional layer;
• performing an ashing process on the multi-greyscale mask layer;
• patterning the electrode layer by using the metal functional layer as a mask;
• and
• further patterning the metal functional layer by using the multi-greyscale mask layer subjected to the ashing process as a mask,
• wherein the step of forming the insulating protection layer further comprises:
• forming a metal layer on the electrode layer;
• and
• performing an oxidation process on the metal layer to obtain a transparent and insulating metal oxide layer serving as the insulating protection layer.