Chemical vapor deposition of titanium from titanium tetrachloride and hydrocarbon reactants

• US 7,268,078 B2
• Filed: 12/09/2005
• Issued: 09/11/2007
• Est. Priority Date: 01/02/1996
• Status: Expired due to Fees

• Current Assignee: Conversant Intellectual Property Management Inc (MOSAID Technologies Inc. (f/k/a Conversant Intellectual Property Management))
• Original Assignee: Micron Technology, Inc.
• Inventors: Iyer, Ravi, Sharan, Sujit
• Primary Examiner(s): Everhart; Caridad
• Application Number:
  US11/298,978
• Publication Number:
  US 20060134912A1
• Time in Patent Office: 641 Days
• Field of Search: 257/E21.168, 438/685, 438/681, 438/909
• US Class Current: 438/685
• CPC Class Codes: C23C 16/08 from metal halides
• CPC Class Codes: H01L 21/28556 by chemical means, e.g. CVD, LPCVD, PECVD, laser CVD H01L21/28518 - H01L21/28537 and H01L21/28568 take precedence
• CPC Class Codes: H01L 21/28568 the conductive layers comprising transition metals H01L21/28518 takes precedence
• CPC Class Codes: Y10S 438/909 Controlled atmosphere

Abstract

A process for depositing titanium metal layers via chemical vapor deposition is disclosed. The process provides deposited titanium layers having a high degree of conformality, even in trenches and contact openings having aspect ratios greater than 1:5.

Claims

1. A plasma enhanced chemical vapor deposition process comprising:

admitting a hydrocarbon gas and a titanium gas into a chamber;

forming a plasma in the chamber having a power level substantially greater than a first ionization energy but less than a second ionization energy of the hydrocarbon gas for forming hydrocarbon radicals therein; and

reacting a material adsorbed on the surface of a substrate with some of the radicals formed from the hydrocarbon gas to react with some chlorine atoms from the titanium gas for depositing titanium metal on a portion of a surface of the substrate.

2. The process of claim 1, wherein the hydrocarbon gas is selected from a group of compounds comprising C_nH_2n+2, C_nH_2n and C_nH_2n−

2.

3. The process of claim 1, further comprising:

mounting the substrate on a susceptor;

heating the susceptor; and

heating the substrate using the susceptor.

4. The process of claim 1, wherein the hydrocarbon gas includes a hydrocarbon gas mixed with a carrier gas selected from a group consisting of helium and argon.

5. The process of claim 1, wherein the chamber comprises a hot wall chamber.

6. The process of claim 1, wherein the chamber comprises a deposition chamber for maintaining a pressure within a range of about 2 torr to about 100 torr.

7. The process of claim 1, wherein the chamber comprises a chamber for maintaining a pressure within a preferred range of about 2 torr to about 5 torr.

8. The process of claim 1, wherein the substrate comprises a semiconductor wafer.

9. The process of claim 1, wherein the hydrocarbon gas comprises an alkane having fewer than five carbon atoms per molecule.

10. The process of claim 9, wherein the hydrocarbon gas includes methane.

11. The process of claim 1, further comprising:

removing reaction products from the chamber during the process.

12. The process of claim 11, wherein an alkyl chloride gas comprises a reaction product.

13. The process of claim 1, wherein the titanium gas includes a titanium tetrachioride gas mixed with a carrier gas selected from a group consisting of helium, argon and hydrogen.

14. The process of claim 13, wherein the titanium gas includes titanium tetrachioride gas introduced into the carrier gas using a bubbler apparatus.

15. The process of claim 13, wherein a liquid injector sprays the titanium tetrachloride gas and passes the titanium tetrachloride gas through a vaporizer.

16. The process of claim 1, wherein the plasma comprises a plasma produced with a radio frequency source.

17. The process of claim 16, wherein the radio frequency source comprises a radio frequency source having a power setting within a range of about 20 watts to about 100 watts.

18. The process of claim 16, wherein the radio frequency source comprises a radio frequency source having a frequency greater than about 10 KHz.

19. The process of claim 1, further comprising:

premixing the titanium gas and the hydrocarbon gas before being admitted to the chamber.

20. The process of claim 19, wherein a ratio of the hydrocarbon gas to the titanium gas comprising the premixture thereof comprises a ratio of between about four and about one thousand to one.

21. A plasma enhanced chemical vapor deposition process comprising:

admitting hydrocarbon gas and titanium tetrachioride into a chamber;

forming a plasma within the chamber of the hydrocarbon gas for forming hydrocarbon radicals;

maintaining the plasma at a power level substantially greater than a first ionization energy, but less than a second ionization energy, of the hydrocarbon gas for forming the hydrocarbon radicals; and

reacting a material adsorbed on a surface of a semiconductor wafer with some of the hydrocarbon radicals to react with some chlorine atoms from the titanium tetrachioride for forming chlorinated hydrocarbon molecules for depositing titanium metal on a portion of the surface of the semiconductor wafer.

22. The process of claim 21, further comprising:

maintaining the chamber at a pressure within a range of about 2 torr to about 10 torr.

23. The process of claim 21, wherein the power level comprises a radio frequency source operating at a power setting within a range of about 20 watts to about 100 watts and at a frequency greater than about 10 KHz.

24. The process of claim 21, further comprising:

premixing the titanium tetrachloride and the hydrocarbon gas for their admission to the chamber in a ratio of hydrocarbon gas to the titanium tetrachloride being between about four and about one thousand to one.

25. The process of claim 21, wherein the hydrocarbon gas includes methane.

26. The process of claim 21, wherein the hydrocarbon gas includes a hydrocarbon gas selected from a group consisting of compounds C_nH_2n+2, C_nH_2n and C_nH_2n−

2.