Thin film transistor with sub-gates and schottky source/drain and a manufacturing method of the same

A manufacturing method for a thin film transistor with sub-gates and Schottky source/drain, comprising:

• providing an insulation substrate;
• forming an island-shaped semiconductor layer of silicon on the insulation substrate;
• forming a gate dielectric layer on the surface of the island-shaped semiconductor layer;
• forming an island-shaped main gate layer on the gate dielectric layer;
• forming insulation spacers on the side walls of the island-shaped main gate layer;
• removing the gate dielectric layer on the two sides of the insulation spacers to expose the island-shaped semiconductor layer;
• forming a metal layer of Ti, Co, Pt or Ni by electroless plating, on the main gate layer, exposed island-shaped semiconductor layer and insulation spacers;
• wherein a metal salt of Ni2+, Pd2+, Pt2+, Cu2+, Ag+, Au3+, or Co2+ is used as the precursor, which is dissolved in a HF, BOE, or NH4F+HF solution to become a reaction solution for electroless plating;
• the reaction solution is then reacted with the exposed portions of the semiconductor layer to obtain the replacement layer;
• thermal-processing and reacting the metal layer and the exposed island-shaped semiconductor layer in a rapid thermal reactor at a temperature range of 450-650° C.;
• or in a thermal furnace at a temperature range of 200-500° C. to form the replacement layer;
• wherein the replacement layer and the island-shaped semiconductor layer existing underneath the insulation spacers form a Schottky contact, which serves as the Schottky source/drain in the thin film transistor;
• removing the unreacted metal layer to become the metal-containing replacement layer;
• forming an insulation layer to cover the main gate layer, insulation spacers, and the Schottky source/drain;
• planarizing the insulation layer;
• and
• forming an island-shaped sub-gate layer over the top of the main gate layer, the two ends of the island-shaped sub-gate layer overlap with the Schottky source/drain respectively.

A manufacturing method for a thin film transistor with sub-gates and Schottky source/drain, comprising:

• providing an insulation substrate;
• forming an island-shaped semiconductor layer of silicon on the insulation substrate;
• forming a gate dielectric layer on the surface of the island-shaped semiconductor layer;
• forming an island-shaped main gate layer on the gate dielectric layer;
• forming insulation spacers on the side walls of the island-shaped main gate layer;
• removing the gate dielectric layer on the two sides of the insulation spacers to expose the island-shaped semiconductor layer;
• forming a metal layer using precursor containing Ni2+ by electroless plating, on the main gate layer, exposed island-shaped semiconductor layer and insulation spacers;
• the precursor is dissolved in a HF, BOE, or NH4F+HF solution to become a reaction solution for electroless plating;
• the reaction solution is then reacted with the exposed portions of the semiconductor layer to obtain the replacement layer;
• subjecting the island-shaped semiconductor layer underneath the insulation spacers and the island-shaped main gate layer to recrystallization at a temperature of 400-600° C. in a nitrogen- or inert gas-filled environment;
• thermal-processing and reacting the metal layer and the exposed island-shaped semiconductor layer in a rapid thermal reactor at a temperature range of 450-650° C.;
• or in a thermal furnace at a temperature range of 200-500° C. to form the replacement layer;
• wherein the replacement layer and the island-shaped semiconductor layer existing underneath the insulation spacers form a Schottky contact, which serves as the Schottky source/drain in the thin film transistor;
• removing the unreacted metal layer to become the metal-containing replacement layer;
• forming an insulation layer to cover the main gate layer, insulation spacers, and the Schottky source/drain;
• planarizing the insulation layer;
• and
• forming an island-shaped sub-gate layer over the top of the main gate layer, the two ends of the island-shaped sub-gate layer overlap with the Schottky source/drain respectively.