Fabrication method of forming silicon carbide MOSFET

A fabrication method of forming a silicon carbide MOSFET, the fabrication method comprising:

• providing a semiconductor substrate, the semiconductor substrate having a silicon carbide layer;
• providing a P-well mask on the semiconductor substrate and implanting the semiconductor substrate through the P-well mask to form a P-well region;
• disposing a spacer on sidewall of the P-well mask and implanting N-plus ions at the P-well region through the spacer to form an N-plus layer;
• removing the P-well mask and the spacer;
• disposing a P-plus mask on the semiconductor substrate and implanting P-plus ions through the P-plus mask to form a P-plus layer, the P-plus layer being disposed between the two N-plus layers;
• removing the P-plus mask and disposing a gate oxide layer on the semiconductor substrate by an oxidation process;
• disposing a polysilicon layer and a dielectric layer, the polysilicon layer being disposed on the gate oxide layer and the dielectric layer being disposed on the polysilicon layer;
• etching the polysilicon layer and the dielectric layer by using the same mask to define a poly gate and a first interlayer dielectric layer;
• disposing a second interlayer dielectric layer on sidewall of the poly gate and the first interlayer dielectric layer and the second interlayer dielectric layer being formed by dielectric material deposition, the first interlayer dielectric layer comprising oxide dielectric material and the second interlayer dielectric layer comprising nitride dielectric material;
• defining an opening between each two second interlayer dielectric layers by a dry etching process, the opening exposes the P-plus layer and a portion of the two N-plus layer adjacent to the P-plus layer;
• disposing a metal layer to fill the opening and to cover the first interlayer dielectric layer and the second interlayer dielectric layer, the poly gate being isolated from the metal layer by the first interlayer dielectric layer and the second interlayer dielectric layer, the metal layer contacts both the N-plus layer and the P-plus layer in same plane.