Method of fabricating a MOS transistor having a gate insulation layer with a lateral portion and a vertical portion
A MOS transistor suppressing a short channel effect includes a substrate, a first diffusion region and a second diffusion region separated from each other by a channel region in an upper portion of the substrate, a gate insulating layer including a first gate insulating layer disposed on a surface of the substrate in the channel region and a second gate insulating layer having a specified depth from the surface of the substrate to be disposed between the first diffusion region and the channel region, and a gate electrode disposed on the first gate insulating layer.
1. A method for fabricating a MOS transistor, the MOS transistor having an inversion layer between a first diffusion region and a second diffusion region, the method comprising:
forming a groove of a specified depth in a substrate, wherein the groove is positioned between the first diffusion region and the inversion layer;
in a single act, forming an insulating layer on the substrate so as to form both (1) a first gate insulating layer that is disposed over the substrate and (2) a second gate insulating layer that fully fills in the groove, wherein the second gate insulating layer is provided with a thickness that is sufficient to block carriers from moving along a surface of the substrate through the second gate insulating layer such that the carriers move around the second gate insulating layer from the first diffusion region to the inversion layer; and
forming a gate electrode over the first gate insulating layer.
2. The method according to claim 1 , wherein the depth of the groove is about 30 nm to 100 nm.
3. The method according to claim 1 , wherein the groove is formed by employing a wet etching method or a dry etching method using plasma.
4. The method according to claim 1 , wherein the insulating layer is formed of a silicon oxide layer.
5. The method according to claim 4 , wherein the first gate insulating layer and the second gate insulating layer of the silicon oxide layer are formed by using a wet oxidation method or a dry oxidation method.
6. The method according to claim 1 , further comprising:
performing channel ion implantation in a region adjacent to the second gate insulating layer.
7. A method for fabricating a semiconductor device, the semiconductor device having an inversion layer between a source region and a drain region, the method comprising:
forming a first groove adjacent to the source region and a second groove adjacent to the drain region, wherein the first groove is positioned between the source region and the inversion layer, and the second groove is positioned between the drain region and the inversion layer;
in a single act, forming an insulating layer over the substrate to form a gate insulating layer that is disposed over the inversion layer and fills the first and second grooves, wherein the gate insulating layer in the first and second grooves is provided with a sufficient thickness to block carriers from moving along a surface of the substrate through the gate insulating layer such that the carriers move around the gate insulating layer from the source region to the drain region through the inversion layer; and
forming a gate electrode over the gate insulating layer,
wherein the source region, the drain region, and the gate electrode together define a MOS transistor.
8. The method according to claim 7 , wherein a depth of the first groove is equal to that of the second groove.
9. The method according to claim 7 , wherein a depth of the first groove is different from that of the second groove.