Method for making a semiconductor device including band-engineered superlattice having 3/1-5/1 germanium layer structure

• US 7,071,119 B2
• Filed: 11/18/2004
• Issued: 07/04/2006
• Est. Priority Date: 06/26/2003
• Status: Active Grant

• Current Assignee: Atomera Incorporated
• Original Assignee: RJ Mears LLC (Atomera Incorporated)
• Inventors: Dukovski, Ilija, Hytha, Marek, Mears, Robert J., Yiptong, Jean Augustin Chan Sow Fook, Kreps, Scott A.
• Primary Examiner(s): Nelms, David
• Assistant Examiner(s): Nguyen, Thinh T
• Application Number:
  US10/992,422
• Publication Number:
  US 20050087738A1
• Time in Patent Office: 593 Days
• Field of Search: 438/761, 438/162, 438/763, 438/479
• US Class Current: 438/761
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: H01L 21/823807 with a particular manufacturing method of the channel structures, e.g. channel implants, halo or pocket implants, or channel materials
• CPC Class Codes: H01L 29/1054 with a variation of the composition, e.g. channel with strained layer for increasing the mobility
• CPC Class Codes: H01L 29/152 with quantum effects only in vertical direction, i.e. layered structures with quantum effects solely resulting from vertical potential variation
• CPC Class Codes: H01L 29/155 Comprising only semiconductor materials H01L29/154 takes precedence
• CPC Class Codes: H01L 29/7833 with lightly doped drain or source extension, e.g. LDD MOSFET's; DDD MOSFET's for thin film transistors H01L29/78618

Abstract

A semiconductor device includes a superlattice that, in turn, includes a plurality of stacked groups of layers. The device may also include regions for causing transport of charge carriers through the superlattice in a parallel direction relative to the stacked groups of layers. Each group of the superlattice may include a plurality of stacked base semiconductor monolayers defining a base semiconductor portion and an energy band-modifying layer thereon. Moreover, the energy-band modifying layer may include at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions. Accordingly, the superlattice may have a higher charge carrier mobility in the parallel direction than would otherwise be present.

Claims

1. A method for making a semiconductor device comprising:

forming a superlattice comprising a plurality of stacked groups of layers;

each group of layers of the superlattice comprising a plurality of stacked base germanium monolayers defining a base germanium portion and an energy band-modifying layer thereon;

the groups of layers arranged in an alternating pattern of first and second groups of layers, with each first group of layers comprising three base germanium monolayers, and each second group of layers comprising five base germanium monolayers;

the energy-band modifying layer comprising at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base germanium portions.

2. The method of claim 1 wherein the superlattice has a common energy band structure therein.

3. The method of claim 1 wherein the superlattice has a higher charge carrier mobility in at least one direction than would otherwise be present.

4. The method of claim 3 wherein the higher charge carrier mobility results from a lower conductivity effective mass for the charge carriers in a parallel direction than would otherwise be present.

5. The method of claim 4 wherein the lower conductivity effective mass is less than two-thirds the conductivity effective mass that would otherwise occur.

6. The method of claim 3 wherein the charge carriers having the higher mobility comprise at least one of electrons and holes.

7. The method of claim 1 wherein each energy band-modifying layer comprises oxygen.

8. The method of claim 1 wherein each energy band-modifying layer is a single monolayer thick.

9. The method of claim 1 wherein forming the superlattice comprises forming a base germanium cap layer on an uppermost group of layers.

10. The method of claim 1 wherein each non-semiconductor monolayer is thermally stable through deposition of a next layer.

11. The method of claim 1 wherein each energy band-modifying layer comprises a non-semiconductor selected from the group consisting of oxygen, nitrogen, fluorine, and carbon-oxygen.

12. The method of claim 1 wherein forming the superlattice comprises forming the superlattice adjacent a substrate.

13. The method of claim 1 further comprising implanting at least one type of conductivity dopant in the superlatice.

14. The method of claim 1 wherein the superlattice defines a channel of a transistor.

15. A method for making a semiconductor device comprising:

providing a substrate; and

forming a superlattice comprising a plurality of stacked groups of layers adjacent the substrate;

each group of layers of the superlattice comprising a plurality of stacked base germanium monolayers defining a base germanium portion and an energy band-modifying layer thereon;

the groups of layers arranged in an alternating pattern of first and second groups of layers, with each first group of layers comprising three base germanium monolayers, and each second group of layers comprising five base germanium monolayers;

the energy-band modifying layer comprising at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base germanium portions, the superlattice thereby having a higher charge carrier mobility in at least one direction than would otherwise be present.

16. The method of claim 15 wherein the superlattice has a common energy band structure therein.

17. The method of claim 15 wherein the higher charge carrier mobility results from a lower conductivity effective mass for the charge carriers in a parallel direction than would otherwise be present.

18. The method of claim 17 wherein the lower conductivity effective mass is less than two-thirds the conductivity effective mass that would otherwise occur.

19. The method of claim 15 wherein the charge carriers having the higher mobility comprise at least one of electrons and holes.

20. The method of claim 15 wherein each energy band-modifying layer comprises oxygen.

21. The method of claim 15 wherein each energy band-modifying layer is a single monolayer thick.

22. The method of claim 15 wherein forming the superlattice further comprises forming a base germanium cap layer on an uppermost group of layers.

23. The method of claim 15 wherein each non-semiconductor monolayer is thermally stable through deposition of a next layer.

24. The method of claim 15 wherein each energy band-modifying layer comprises a non-semiconductor selected from the group consisting of oxygen, nitrogen, fluorine, and carbon-oxygen.

25. The method of claim 15 further comprising implanting at least one type of conductivity dopant in the superlattice.

26. The method of claim 15 wherein the superlattice defines a channel of a transistor.