Apparatus and method for manufacturing multi-component oxide heterostructures
Certain embodiments disclosed herein relate to the formation of multi-component oxide heterostructures (MCOH) using surface nucleation to pattern the atomic layer deposition (ALD) of perovskite material followed by patterned etch and metallization to produce ultra-high density MCOH nano-electronic devices. Applications include ultra-high density MCOH memory and logic, as well as electronic functionality based on single electrons, for example a novel flash memory cell Floating-Gate (FG) transistor with LaAlO 3 as a gate tunneling dielectric. Other types of memory devices (DIMMS, DRAM, and DDR) made with patterned ALD of LaAlO 3 as a gate dielectric are also possible.
1. A method of forming an array of multi-component oxide heterostructures, the method comprising:
exposing a substrate comprising a SrTiO 3 top layer to a digital beam in a first chamber, the first chamber comprising a focused ion beam to introduce site specific surface nucleation and to generate a density of oxygen vacancies;
moving the exposed substrate into a second chamber to induce thermal activation of said substrate;
moving the thermally activated substrate into a third chamber;
introducing a lanthanum containing precursor into the third chamber;
introducing an aluminum containing precursor into the third chamber; and
controlling the introducing of the lanthanum containing precursor and the introducing of the aluminum containing precursor to form by patterned atomic layer deposition a dielectric layer comprising LaAlO 3 having a thickness of 2 to 4 unit cells to form a well-defined high density array of multi-component oxide heterostructures.
2. The method of claim 1 , wherein, after introducing the lanthanum containing precursor into the third chamber, introducing a first oxygen containing precursor into the third chamber.
3. The method of claim 2 , wherein, after introducing the aluminum containing precursor into the third chamber, introducing a second oxygen containing precursor into the third chamber.
4. The method of claim 1 , further comprising repeating for a number of cycles the introducing of the lanthanum containing precursor and the aluminum containing precursor to achieve a thickness.
5. A method of forming a multi-component oxide heterostructure, the method comprising:
forming nucleation sites on a SrTiO 3 surface of a substrate with a focused ion beam by chemically modifying portions of the surface of the substrate;
depositing at least one layer of LaAlO 3 at the nucleation sites.
6. The method of claim 5 , wherein the depositing at least one layer comprises atomic layer deposition.
7. The method of claim 5 , further comprising thermally activating the substrate after forming the nucleation sites.
8. The method of claim 5 , wherein the depositing the at least one layer comprises reacting a gas with the nucleation sites.
9. The method of claim 5 , wherein the focused ion beam is a digital beam.
10. The method of claim 9 , wherein the digital beam comprises:
forming a stream of particles;
collimating the stream of particles along an axis of propagation to form the focused ion beam; and
digitizing the focused ion beam.
11. The method of claim 9 , wherein the digitizing the focused ion beam comprises creating temporally and spatially resolved digital flashes comprising at least one particle per digital flash.
12. The method of claim 9 , further comprising deflecting the digital beam with a series of deflectors disposed longitudinally along an axis of the digital beam.
13. The method of claim 5 , further comprising forming a conformal mask on the substrate before forming the nucleation sites.
14. The method of claim 13 , wherein the forming a conformal mask comprises:
depositing a mask layer on the surface of the substrate;
etching portions of the mask layer to expose portions of the surface of the substrate.
15. The method of claim 5 , wherein the at least one layer comprises a thickness of two to four unit cells.
16. The method of claim 15 , wherein the at least layer has a thickness of three unit cells.
17. The method of claim 15 , wherein the at least one layer comprises a layer of La 3+ O 2− .
18. The method of claim 17 , wherein the at least one layer comprises a layer of Al 3+ O 2 4− .
19. A method of forming an array of multi-component oxide heterostructures, the method comprising:
exposing a substrate comprising a LaAlO 3 top layer to a digital beam in a first chamber comprising a focused ion beam to introduce site specific surface nucleation;
moving the exposed substrate into a second chamber to induce thermal activation of said substrate;
moving the thermally activated substrate into a third chamber;
introducing a lanthanum containing precursor into the third chamber;
introducing a vanadium containing precursor into the third chamber;
introducing a second lanthanum precursor into the third chamber;
introducing an aluminum precursor into the third chamber;
controlling the introducing of the lanthanum containing precursor and the introducing of the vanadium containing precursor to form by patterned atomic layer deposition a dielectric layer comprising LaVO 3 having a dielectric layer thickness of 5 to 20 unit cells to form a well-defined high density array of multi-component oxide heterostructures; and
controlling the introducing of the second lanthanum containing precursor and the introducing of the aluminum containing precursor to form by patterned atomic layer deposition a thin dielectric capping layer comprising LaAlO 3 having a capping layer thickness of 2 to 4.5 unit cells.
20. The method of claim 19 , further comprising repeating for a number of cycles the introducing of the lanthanum containing precursor and the vanadium containing precursor to achieve the dielectric layer thickness; and further comprising repeating for a number of cycles the introducing of the second lanthanum containing precursor and the aluminum containing precursor to achieve the capping layer thickness.
21. The method of claim 19 , wherein the dielectric layer forms quantum wells.
22. The method of claim 21 , wherein, the capping layer dopes electrons into the LaVO 3 quantum wells.
23. The method of claim 21 , wherein, the capping layer dopes holes into the LaVO 3 quantum wells.
24. The method of claim 19 , wherein, at least one of the multi-component oxide heterostructures is n-type and the capping layer thickness is between 2.5 and 4.5 unit cells.
25. The method of claim 19 , wherein, at least one of the multi-component oxide heterostructures is p-type and the capping layer thickness is between 2 and 4 unit cells.
26. The method of claim 19 , wherein, at least one of the multi-component oxide heterostructures is a NMOS device comprising a n-type MCOH material.
27. The method of claim 19 , wherein, at least one of the multi-component oxide heterostructures is a PMOS device comprising a p-type MCOH material.
28. The method of claim 19 , further comprising pattern etching the capping layer and the dielectric layer with a digital beam to form sites for ohmic contacts; exposing the sites for ohmic contacts to a digital beam to introduce ohmic contact surface nucleation sites; and depositing an electrical conductor onto the ohmic contact surface nucleation sites.
29. The method of claim 19 , wherein, both p-type and n-type MCOH materials are grown side-by-side on the same substrate by patterned nucleation and then fabricated into MCOH CMOS devices by patterned metallization, etch, and implant to form ohmic contacts, interconnects, refractory metal gate lines, and electrical isolation barriers.
30. The method of claim 19 , further comprising forming a PMOS device comprising at least one of the multi-component oxide heterostructures; forming a NMOS device comprising at least one of the multi-component oxide heterostructures, wherein the PMOS device neighbors the NMOS device and the PMOS device is electrically isolated from the NMOS device by at least one electrical isolation barrier.
31. The method of claim 30 , wherein forming the NMOS device and forming the PMOS device comprise pattern etching the capping layer and the dielectric layer with a digital beam to form sites for ohmic contacts; exposing the sites for ohmic contacts to a digital beam to introduce ohmic contact surface nucleation sites; and depositing an electrical conductor onto the ohmic contact surface nucleation sites.