Method and structure for shallow trench isolation to mitigate active shorts
A shallow trench isolation region is provided in which void formation is substantially or totally eliminated therefrom. The shallow trench isolation mitigates active shorts between two active regions of a semiconductor substrate. The shallow trench isolation region includes a bilayer liner which is present on sidewalls and a bottom wall of a trench that is formed in a semiconductor substrate. The bilayer liner of the present disclosure includes, from bottom to top, a shallow trench isolation liner, e.g., a semiconductor oxide and/or nitride, and a high k liner, e.g., a dielectric material having a dielectric constant that is greater than silicon oxide.
1. A method of forming a shallow trench isolation region, said method comprising:
forming a pad stack on an uppermost surface of a semiconductor substrate, wherein said pad stack includes, from bottom to top, a semiconductor oxide and a semiconductor nitride;
forming a trench into both said pad stack and said semiconductor substrate, said trench is defined by sidewalls and a bottom wall;
forming a shallow trench isolation liner directly on said sidewalls and said bottom wall of said trench, but not on any portion of the pad stack;
forming a high-k liner selected from at least one of a dielectric metal oxide, a dielectric metal nitride, a dielectric metal oxynitride, a dielectric metal silicate, and a dielectric nitrided metal silicate directly on exposed surfaces of said shallow trench isolation liner, and on exposed sidewall surfaces of said pad stack and a topmost surface of said pad stack;
forming a trench dielectric material in direct physical contact with exposed surfaces of the high-k liner, completely filling said trench, and having an uppermost surface that is coplanar with said topmost surface of said pad stack;
removing remaining portions of said semiconductor nitride to expose a topmost surface of remaining portions of said semiconductor oxide and to provide a protruding portion of the shallow trench isolation region which extends above said topmost surface of said remaining portions of said semiconductor oxide;
removing exposed portions of the high-k liner from said protruding portion of the shallow trench isolation region; and
removing a remaining protruding portion of said shallow trench isolation region and said remaining portions of said semiconductor oxide.
2. The method of claim 1 wherein said forming the trench comprises lithography and etching.
3. The method of claim 1 wherein said high-k liner is selected from HfO 2 , ZrO 2 , La 2 O 3 , Al 2 O 3 , TiO 2 , SrTiO 3 , LaAlO 3 , Y 2 O 3 , HfO x N y , ZrO x N y , La 2 O x N y , Al 2 O x N y , TiO x N y , SrTiO x N y , LaAlO x N y , Y 2 O x N y , a silicate thereof, an alloy thereof or a multilayered stack thereof, wherein x is independently from 0.5 to 3 and y is independently from 0 to 2.
4. The method of claim 1 wherein said high-k liner is HfO 2 , hafnium silicate or hafnium silicon oxynitride.
5. The method of claim 1 further comprising forming a first semiconductor device on a first active region of said semiconductor substrate and forming a second semiconductor device on a second active region of said semiconductor substrate, wherein said shallow trench isolation region separates the first active region from said second active region.
6. A method of forming a shallow trench isolation region, said method comprising:
forming a pad stack on an uppermost surface of a semiconductor substrate, wherein said pad stack includes, from bottom to top, a semiconductor oxide and a semiconductor nitride;
forming a trench into both said pad stack and said semiconductor substrate, said trench is defined by sidewalls and a bottom wall;
forming a shallow trench isolation liner directly on said sidewalls and said bottom wall of said trench, but not on any portion of the pad stack;
forming a high-k liner selected from at least one of a dielectric metal oxide, a dielectric metal nitride, a dielectric metal oxynitride, a dielectric metal silicate, and a dielectric nitrided metal silicate directly on exposed surfaces of said shallow trench isolation liner; and
forming a trench dielectric material in direct physical contact with exposed surfaces of the high-k liner, completely filling said trench, wherein no surface of the trench dielectric material directly contacts any portion of the semiconductor substrate, and wherein said forming the trench dielectric material includes depositing the trench dielectric material, annealing the trench dielectric material, planarizing and adjusting a height of the trench dielectric material such that the height of the trench dielectric material after said adjusting is coplanar with an upper surface of remaining portions of said semiconductor oxide, and removing said remaining portions of said semiconductor oxide and a portion of said high-k liner and a portion of said trench dielectric material.
7. The method of claim 6 wherein said forming the trench comprises lithography and etching.
8. The method of claim 6 wherein said high-k liner is selected from HfO 2 , ZrO 2 , La 2 O 3 , Al 2 O 3 , TiO 2 , SrTiO 3 , LaAlO 3 , Y 2 O 3 , HfO x N y , ZrO x N y , La 2 O x N y , Al 2 O x N y , TiO x N y , SrTiO x N y , LaAlO x N y , Y 2 O x N y , a silicate thereof, an alloy thereof or a multilayered stack thereof, wherein x is independently from 0.5 to 3 and y is independently from 0 to 2.
9. The method of claim 6 wherein said high-k liner is HfO 2 , hafnium silicate or hafnium silicon oxynitride.
10. The method of claim 6 further comprising forming a first semiconductor device on a first active region of said semiconductor substrate and forming a second semiconductor device on a second active region of said semiconductor substrate, wherein said shallow trench isolation region separates the first active region from said second active region.