Semiconductor device with bulb-type recessed channel and method for fabricating the same
View Patent ↗A method for fabricating a semiconductor device includes providing a substrate having a bulb-type recessed region, forming a gate insulating layer over the bulb-type recessed region and the substrate, and forming a gate conductive layer over the gate insulating layer. The gate conductive layer fills the bulb-type recessed region. The gate conductive layer includes two or more conductive layers and a discontinuous interface between the conductive layers.
1. A semiconductor device comprising:
a substrate;
a bulb-type recessed region formed in the substrate;
a gate insulating layer formed over the bulb-type recessed region and the substrate;
a vacancy-removed first gate conductive layer formed over the gate insulating layer, wherein vacancies melted in equilibrium inside the vacancy-removed first gate conductive layer are diffused out by a thermal treatment;
a second gate conductive layer formed over the vacancy-removed first gate conductive layer to fill in the bulb-type recessed region, and
a discontinuous interface between the vacancy-removed first gate conductive layer and the second gate conductive layer.
2. The semiconductor device of claim 1 , wherein a first thickness of the vacancy-removed first gate conductive layer is smaller than half of a width of an opening of the bulb-type recessed region.
3. The semiconductor device of claim 1 , wherein the vacancy-removed first gate conductive layer and the second gate conductive layer comprise a silicon layer.
4. The semiconductor device of claim 3 , wherein the silicon layer is doped with impurities.
5. The semiconductor device of claim 1 , wherein the vacancy-removed first gate conductive layer comprises a silicon layer on which the thermal treatment is performed.