Semiconductor device structures comprising a spacer feature having multiple spacer layers are provided. In one example, a semiconductor device includes an active area on a substrate, the active area comprising a source/drain region, a gate structure over the active area, the source/drain region being proximate the gate structure, a spacer feature having a first portion along a sidewall of the gate structure and having a second portion along the source/drain region, wherein the first portion of the spacer feature comprises a bulk spacer layer along the sidewall of the gate structure, wherein the second portion of the spacer feature comprises the bulk spacer layer and a treated seal spacer layer, the treated seal spacer layer being disposed along the source/drain region and between the bulk spacer layer and the source/drain region, and a contact etching stop layer on the spacer feature.

A fabrication method of forming a silicon carbide MOSFET is provided. The fabrication method includes the step of providing a semiconductor substrate. A P-well region is formed by implanting the semiconductor substrate through the P-well mask. A spacer is disposed on sidewall of the P-well mask and the P-well region is implanted to form a P-plus layer and an N-plus layer. A gate oxide layer, a poly gate and a first interlayer dielectric layer are formed on the semiconductor substrate. The first interlayer dielectric layer is etched to form an opening and the opening exposes the P-plus layer. A metal layer is disposed to cover the opening and the first interlayer dielectric layer.

A shielded gate trench MOSFET device structure is provided. The device structure includes MOS gate trenches and p body contact trenches formed in an n type epitaxial silicon layer overlying an n+ silicon substrate. Each MOS gate trench includes a gate trench stack having a lower n+ shield poly silicon layer separated from an upper n+ gate poly silicon layer by an inter poly dielectric layer. The upper and lower poly silicon layers are also laterally isolated at the areas where the lower poly silicon layer extends to silicon surface by selectively removing portion of the upper poly silicon and filling the gap with a dielectric material. The method is used to form both MOS gate trenches and p body contact trenches in self-aligned or non self-aligned shielded gate trench MOSFET device manufacturing.

An embodiment relates to a method comprising obtaining a SiC substrate comprising a N+ substrate and a N− drift layer; depositing a first hard mask layer on the SiC substrate and patterning the first hard mask layer; performing a p-type implant to form a p-well region; depositing a second hard mask layer on top of the first hard mask layer; performing an etch back of at least the second hard mask layer to form a sidewall spacer; implanting N type ions to form a N+ source region that is self-aligned; and forming a MOSFET.

A shielded gate trench MOSFET device structure is provided. The device structure includes MOS gate trenches and p body contact trenches formed in an n type epitaxial silicon layer overlying an n+ silicon substrate. Each MOS gate trench includes a gate trench stack having a lower n+ shield poly silicon layer separated from an upper n+ gate poly silicon layer by an inter poly dielectric layer. The upper and lower poly silicon layers are also laterally isolated at the areas where the lower poly silicon layer extends to silicon surface by selectively removing portion of the upper poly silicon and filling the gap with a dielectric material. The method is used to form both MOS gate trenches and p body contact trenches in self-aligned or non self-aligned shielded gate trench MOSFET device manufacturing.

A method of forming a vertical fin field effect device is provided. The method includes, forming a vertical fin on a substrate, forming a masking block on the vertical fin, wherein the masking block extends a distance outward from the vertical fin sidewalls and endwalls, and a portion of the substrate surrounding the masking block is exposed. The method further includes removing at least a portion of the exposed portion of the substrate to form a recess and a fin mesa below the vertical fin, removing a portion of the fin mesa to form an undercut recess below an overhanging portion of the masking block, forming a spacer layer on the masking block and in the undercut recess, and removing a portion of the spacer layer to form an undercut spacer in the undercut recess.

A semiconductor device includes a first active region defined on a substrate, a first gate electrode across the first active region, a first drain region in the first active region at a position adjacent to the first gate electrode, an undercut region between the first active region and the first gate electrode, and a first gate spacer on a side surface of the first gate electrode and extending into the undercut region.

A fabrication method of forming a silicon carbide MOSFET is provided. The fabrication method includes the step of providing a semiconductor substrate. A P-well region is formed by implanting the semiconductor substrate through the P-well mask. A spacer is disposed on sidewall of the P-well mask and the P-well region is implanted to form an N-plus layer. A P-plus mask is disposed on the semiconductor substrate and the semiconductor substrate is implanted to form a P-plus layer. A gate oxide layer, a poly gate and a first interlayer dielectric layer are formed on the semiconductor substrate. A second interlayer dielectric layer is disposed on sidewall of the poly gate and the first interlayer dielectric layer. A metal layer is disposed to cover the first interlayer dielectric layer and the second interlayer dielectric layer.

A fabrication method of forming a silicon carbide MOSFET is provided. The fabrication method includes the step of providing a semiconductor substrate. A P-well region is formed by implanting the semiconductor substrate through the P-well mask. A spacer is disposed on sidewall of the P-well mask and the P-well region is implanted to form a P-plus layer and an N-plus layer. A gate oxide layer, a poly gate and a first interlayer dielectric layer are formed on the semiconductor substrate. A second interlayer dielectric layer is disposed on sidewall of the poly gate and the first interlayer dielectric layer. The N-plus layer is etched to form an opening and the opening exposes the P-plus layer. A metal layer is disposed to cover the opening, the first interlayer dielectric layer and the second interlayer dielectric layer.

A shielded gate trench MOSFET device structure is provided. The device structure includes MOS gate trenches and p body contact trenches formed in an n type epitaxial silicon layer overlying an n+ silicon substrate. Each MOS gate trench includes a gate trench stack having a lower n+ shield poly silicon layer separated from an upper n+ gate poly silicon layer by an inter poly dielectric layer. The upper and lower poly silicon layers are also laterally isolated at the areas where the lower poly silicon layer extends to silicon surface by selectively removing portion of the upper poly silicon and filling the gap with a dielectric material. The method is used to form both MOS gate trenches and p body contact trenches in self-aligned or non self-aligned shielded gate trench MOSFET device manufacturing.