MOS P-N JUNCTION SCHOTTKY DIODE DEVICE AND METHOD FOR MANUFACTURING THE SAME

摘要

A MOS P-N junction Schottky diode device includes a substrate having a first conductivity type, a field oxide structure defining a trench structure, a gate structure formed in the trench structure and a doped region having a second conductivity type adjacent to the gate structure in the substrate. An ohmic contact and a Schottky contact are formed at different sides of the gate structure. The method for manufacturing such diode device includes several ion-implanting steps to form several doped sub-regions with different implantation depths to constitute the doped regions. The formed MOS P-N junction Schottky diode device has low forward voltage drop, low reverse leakage current, fast reverse recovery time and high reverse voltage tolerance.

主权项

1. A method for fabricating a metal-oxide-semiconductor (MOS) P-N junction Schottky diode device, comprising steps of:
providing a substrate having a first conductivity type; forming a field oxide structure defining a trench structure on the substrate; sequentially forming a conductive semiconductor layer, a first mask layer and a first patterned photo-resist layer defining the conductive semiconductor layer in the trench structure; performing an isotropic etching step on the first mask layer by using the first patterned photo-resist layer as a mask to have the remaining first mask layer shorter than the first patterned photo-resist layer; doping the substrate with ions having a second conductivity type using the first patterned photo-resist layer as a mask to form a first doped sub-region in the substrate; removing the first patterned photo-resist layer; doping the substrate with ions having the second conductivity type by using the remaining first mask layer as a mask to form a second doped sub-region in the substrate shallower than the first doped sub-region, wherein a doped region having the second conductivity type includes the first doped sub-region and the second doped sub-region; removing the remaining first mask layer; partially removing the conductive semiconductor layer to form a gate structure; and forming a top electrode on the trench structure and the field oxide structure, and forming a bottom electrode on a surface of the substrate opposite to the top electrode; wherein an ohmic contact is formed between the top electrode and the second conductivity type of the doped region and a Schottky contact is formed between the top electrode and the first conductivity type of the substrate, and a first side of the gate structure is only adjacent to the second conductivity type of the doped region to form the ohmic contact, and a second side of the gate structure is only adjacent to the first conductivity type of the substrate to form the Schottky contact.