Manufacturing method of a thin film transistor

A manufacturing method of a thin film transistor, the thin film transistor comprising a gate electrode, a gate insulation layer, an active layer, an ohmic contact layer, a source electrode and a drain electrode,

• wherein the method comprises:
• forming the ohmic contact layer by an injection process;
• wherein the method comprises:
• forming a first groove and a second groove communicated with each other in the gate insulation layer;
• forming the active layer in the first groove:
• and forming the ohmic contact layer in the second groove by the injection process;
• wherein a conductivity of the ohmic contact layer is not uniform, and the method comprises:
• forming a photoresist layer on the gate insulation layer;
• performing exposing and developing processes on the photoresist layer by using a multi-tone mask plate so as to form a photoresist-completely-removed region, a first to n-th photoresist-partially-retained regions and a photoresist-completely-retained region, wherein n is an integer equal to or greater than 2, thicknesses of the photoresist in the first to n-th photoresist-partially-retained regions are gradually increased, and the photoresist-completely-removed region corresponds to a region where the active layer is to be formed, the first to n-th photoresist-partially-retained regions correspond to a region where the ohmic contact layer is to be formed, and the photoresist-completely-retained region corresponds to other region;
• etching the gate insulation layer in this photoresist-completely-removed region to form the first groove, and then forming the active layer in the first groove;
• removing the photoresist in the first photoresist-partially-retained region and etching the gate insulation layer in this region to form a first portion of the second groove, and then forming a first sub-ohmic-contact-layer in the first portion of the second groove by using the injection process;
• removing the photoresist in the second photoresist-partially-retained region and etching the gate insulation layer in this region to form a second portion of the second groove, and then forming a second sub-ohmic-contact-layer in the second portion of the second groove by using the injection process;
• in the same way as that for forming the first sub-ohmic-contact-layer and the second sub-ohmic-contact-layer, forming other sub-ohmic-contact-layers until
• removing the photoresist in the n-th photoresist-partially-retained region, etching the gate insulation layer in this region to form a n-th portion of the second groove and forming a n-th sub-ohmic-contact-layer in the n-th portion of the second groove by using the injection process;
• and
• removing the photoresist in the photoresist-completely-retained region.