Controlled composition using plasma-enhanced atomic layer deposition

• US 7,727,864 B2
• Filed: 11/01/2006
• Issued: 06/01/2010
• Est. Priority Date: 11/01/2006
• Status: Active Grant

• Current Assignee: ASM IP Holding B.V. (ASM International NV)
• Original Assignee: ASM America Incorporated (ASM International NV)
• Inventors: Elers, Kai-Erik
• Primary Examiner(s): Smith; Zandra
• Assistant Examiner(s): Perkins; Pamela E
• Application Number:
  US11/591,927
• Publication Number:
  US 20080102613A1
• Time in Patent Office: 1,308 Days
• Field of Search: None
• US Class Current: 438/485
• CPC Class Codes: C23C 16/45525 Atomic layer deposition [ALD]
• CPC Class Codes: C23C 16/4554 Plasma being used non-continuously in between ALD reactions C23C16/56 takes precedence
• CPC Class Codes: C23C 16/50 using electric discharges generation and control of plasma in discharge tubes for surface treatment H01J37/32, H01J37/34
• CPC Class Codes: H01L 21/28088 the final conductor layer next to the insulator being a composite, e.g. TiN
• CPC Class Codes: H01L 29/4966 the conductor material next to the insulator being a composite material, e.g. organic material, TiN, MoSi2 H01L29/4908, H01L29/4983 take precedence
• CPC Class Codes: H01L 29/517 the insulating material comprising a metallic compound, e.g. metal oxide, metal silicate H01L29/518 takes precedence

Abstract

Metallic-compound films are formed by plasma-enhanced atomic layer deposition (PEALD). According to preferred methods, film or thin film composition is controlled by selecting plasma parameters to tune the oxidation state of a metal (or plurality of metals) in the film. In some embodiments, plasma parameters are selected to achieve metal-rich metallic-compound films. The metallic-compound films can be components of gate stacks, such as gate electrodes. Plasma parameters can be selected to achieve a gate stack with a predetermined work function.

Claims

1. A method of depositing a metallic-compound film in a plasma-enhanced atomic layer deposition (PEALD) process, comprising:

alternately and sequentially contacting a substrate in a reaction space with spatially and temporally separated vapor phase pulses of at least three different reactants, the at least three different reactants comprising;

a metal source chemical;

a plasma-excited species; and

a source chemical of a non-metal species desired in the metallic-compound film,

wherein plasma parameters for generating the plasma-excited species are selected to reduce the oxidation state of the metal in the metallic-compound film relative to its oxidation state in the metal source chemical and achieve the metallic-compound film with a predetermined composition.

2. The method of claim 1, wherein alternately and sequentially contacting comprises the steps of:

a) selecting plasma parameters;

b) feeding a vapor-phase pulse of the metal source chemical into the reaction space;

c) feeding into the reaction space a vapor-phase pulse of one of the plasma-excited species and the source chemical of the non-metal species desired in the metallic-compound film;

d) feeding into the reaction space a vapor-phase pulse of the other of the plasma-excited species and the source chemical of the non-metal species desired in the metallic-compound film; and

e) repeating steps a) through d) in a plurality of cycles to form the metallic-compound film over the substrate.

3. The method of claim 2, wherein the species desired in the metallic-compound film is carbon.

4. The method of claim 3, wherein the source chemical of the species desired in the metallic-compound film is selected from the group consisting of alkanes, alkenes and alkynes.

5. The method of claim 2, wherein the species desired in the metallic-compound film is oxygen.

6. The method of claim 5, wherein the source chemical of the species desired in the metallic-compound film is selected from the group consisting of water (H₂O) and oxygen (O₂).

7. The method of claim 2, wherein the species desired in the metallic-compound film is selected from the group consisting of carbon, nitrogen, oxygen and combinations thereof.

8. The method of claim 2, further comprising removing reactants and any reaction by-products from the reaction space after each of the vapor phase pulses.

9. The method of claim 8, wherein removing comprises purging the reaction space with the aid of an inert gas.

10. The method of claim 8, wherein removing comprises pumping the reaction space.

11. The method of claim 2, wherein the species desired in the metallic-compound film is nitrogen.

12. The method of claim 11, wherein the source chemical of the species desired in the metallic-compound film is selected from the group consisting of ammonia (NH₃), hydrazine (N₂H₄), and mixtures thereof.

13. The method of claim 1, wherein the metallic-compound film includes metal selected from the group consisting of titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), rhenium (Re), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), silver (Ag), gold (Au), palladium (Pd), platinum (Pt), rhodium (Rh), iridium (Ir), ruthenium (Ru), osmium (Os) and combinations thereof.

14. The method of claim 1, wherein the metallic-compound film is metal-rich.

15. The method of claim 1, wherein plasma-excited species is selected from the group consisting of excited species of hydrogen (H₂), nitrogen (N₂), ammonia (NH₃) and combinations thereof.

16. The method of claim 1, wherein the metal source chemical is selected from the group consisting of metal halides and metal organic compounds.

17. The method of claim 16, wherein the metal source chemical is selected from the group consisting of metal bromides, metal chlorides, metal fluorides and metal iodides.

18. The method of claim 16, wherein the metal source chemical is selected from the group consisting of metal dialkylamido and metal cyclopentadienyl compounds.

19. The method of claim 1, wherein the species desired in the metallic-compound film is selected from the group consisting of carbon (C), nitrogen (N), oxygen (O) and combinations thereof.

20. The method of claim 1, wherein the plasma parameters are selected from the group consisting of plasma generator power, gas pressure, gas flow rate, plasma generation time and plasma pulse duration.

21. The method of claim 1, wherein plasma-excited species includes excited species of hydrogen (H₂).

22. The method of claim 1, wherein plasma-excited species includes excited species of nitrogen (N₂).

23. The method of claim 1, wherein plasma-excited species includes excited species of hydrogen (H₂) and nitrogen (N₂).

24. The method of claim 1, wherein plasma-excited species includes excited species of ammonia (NH₃).

25. A reaction system comprising the reaction space and a controller configured to perform the method of claim 1.

26. An atomic layer deposition (ALD) process for growing a thin metallic-compound film, comprising alternately and sequentially contacting a substrate in a reaction space with spatially and temporally separated vapor phase pulses of:

a precursor of a metal that forms no more than about one monolayer of adsorbed species on an exposed surface of the substrate, the adsorbed species comprising at least one type of metal;

a plasma-excited species reacting with the metal; and

a source chemical of a species to be incorporated in the thin metallic-compound film,

wherein plasma parameters for generating the plasma-excited species are selected such that the stoichiometric ratio between the metal and the species in the thin metallic-compound film is greater than one.

27. The process of claim 26, wherein the thin metallic-compound film comprises a gate electrode.

28. The process of claim 27, wherein the plasma parameters are selected to achieve a predetermined gate electrode work function.

29. The process of claim 26, wherein the plasma parameters are selected from the group consisting of plasma generator power, gas pressure, gas flow rate, plasma generation time and plasma pulse duration.

30. The process of claim 26, wherein plasma-excited species is selected from the group consisting of excited species of hydrogen (H₂), nitrogen (N₂), ammonia (NH₃), hydrazine (N₂H₄) and combinations thereof.

31. The process of claim 26, wherein the thin metallic-compound film is metal-rich.

32. The process of claim 26, wherein the source chemical is selected from the group consisting of nitrogen-containing compounds, carbon-containing compounds, oxygen-containing compounds and combinations thereof.