High thermal budget compatible punch through stop integration using doped glass
A method of forming a punch through stop region in a fin structure is disclosed. The method may include forming a doped glass layer on a fin structure and forming a masking layer on the doped glass layer. The method may further include removing a portion of the masking layer from an active portion of the fin structure, and removing an exposed portion the doped glass layer that is present on the active portion of the fin structure. A remaining portion of the doped glass layer is present on the isolation portion of the fin structure. Dopant from the doped glass layer may then be diffused into the isolation portion of the fin structure to form the punch through stop region between the active portion of the fin structure and a supporting substrate.
1. A method of forming a punch through stop region in a fin structure comprising:
forming a doped glass layer on a fin structure;
forming a masking layer on the doped glass layer;
removing a portion of the masking layer that is present over an active portion of the fin structure, wherein a remaining portion of the masking layer is present on the doped glass layer that is present on an isolation portion of the fin structure;
removing an exposed vertically orientated portion of the doped glass layer that is present on the active portion of the fin structure and removing horizontal portions of the doped glass layer that are not in direct contact with a sidewall of the fin structure, the horizontal portions of the doped glass layer being removed extending over an underlying supporting substrate for the fin structure, wherein a remaining portion of the doped glass layer is present on the isolation portion of the fin structure; and
diffusing dopant from the doped glass layer into the isolation portion of the fin structure to form the punch through stop region of dopant extending from the active portion of the fin structure to the underlying supporting substrate.
2. The method of claim 1 , wherein the fin structure is formed from a bulk semiconductor substrate, a surface of the bulk semiconductor substrate being etched to form the fin structure, wherein a remaining portion of the bulk semiconductor substrate provide the supporting substrate.
3. The method of claim 2 , wherein etching the bulk semiconductor substrate to form the fin structure comprises:
forming a hard mask layer on a surface of the bulk semiconductor substrate;
patterning the hard mask layer to provide a hard mask; and
etching the bulk semiconductor substrate selectively to the hard mask.
4. The method of claim 1 , wherein forming the doped glass layer comprises depositing a conformal layer on sidewalls and an upper surface of the fin structure.
5. The method of claim 4 , wherein the doped glass layer comprises an n-type or p-type doped silicate glass.
6. The method of claim 4 , wherein forming the masking layer comprises depositing a conformal layer, the masking layer comprises a composition that is etched selectively to at least the hard mask.
7. The method of claim 6 , wherein said removing the masking layer from an active portion of the fin structure comprises:
applying an anisotropic etch to remove the laterally orientated surfaces of the masking layer and to recess the vertically orientated surfaces of the masking layer to provide said exposed portion of the doped glass layer that is present on the active portion of the fin structure; and
removing the exposed portion of the doped glass layer with an isotropic etch.
8. The method of claim 7 , wherein diffusing dopant from the doped glass layer into the isolation portion of the fin structure to form the punch through stop region comprises annealing.