MOSFET device
A method of fabricating a MOSFET device with a multiple T-shaped gate has the following steps. A substrate with an active region and a non-active region is provided, wherein the active region has a plurality of trenches, and the non-active region has a plurality shallow trench isolation structures. A thin insulating layer and a conducting layer are formed in the trenches. The conducting layer is defined to form a gate. The device is implanted with first ions. Then, the device is further implanted with second ions by using a mask, wherein the mask expose the trenches of the active region, and the opening of the mask is wider than the trench. The MOSFET device has at least the following structures. There is a substrate with an active region and a non-active region, wherein the active region has a plurality of trenches and the non-active region has a plurality of shallow trench isolation structures. There is a multiple T-shaped gate with a first part and a second part, wherein the first part is formed between two trenches on the substrate and the second part is formed in the trenches of the active region. There is a source/drain region with a shallow doped region and a deep doped region. The multiple T-shaped gate increases the channel width of the MOSFET device and decreases the short channel effect of the high integrity ICs.
1. A semiconductor structure comprising a substrate having an active region of a first conductive type including a channel region and a non-channel region surrounding the channel region, at least a first trench and a second trench disposed in the active region, the structure comprising:
a thin insulating layer disposed over said first and second trenches partially filling said first and second trenches and being conformal to said first and second trenches;
a gate electrode comprising a first conductive vertical portion, a second conductive vertical portion and a horizontal conductive portion, wherein the conductive first vertical portion is embedded inside the first trench over said thin insulating layer such that said insulating layer and said first conductive vertical portion within the first trench completely fills the first trench, the second conductive vertical portion is embedded inside the second trench over said thin insulating layer such that said insulating layer and said second conductive vertical portion within the second trench completely fills the second trench, and the horizontal conductive portion is disposed over the substrate and connects said first and second conductive vertical portions together; and
a pair of shallow doped regions within the substrate disposed adjacent to and on two opposite sides of each of the first and second conductive vertical portions and the conductive horizontal portion; and a pair of deep doped regions extending respectively from the first pair of shallow doped regions to regions within the substrate deeper than the first and second trenches,
wherein the pair of shallow doped regions form shallow source/drain regions with a shallow channel region therebetween below the conductive horizontal portion; and,
wherein the pair of deep doped regions form deep source/drain regions with two deep channel regions therebetween below the first and second trenches, respectively.
2. The structure according to claim 1 , wherein the thin insulating layer is formed by thermal oxidation.
3. The structure according to claim 1 , wherein a thickness of the thin insulating layer is about 0.1 μm.