STABILIZATION OF FLUORINE-CONTAINING LOW-K DIELECTRICS IN A METAL/INSULATOR WIRING STRUCTURE BY ULTRAVIOLET IRRADIATION

• US 20020033535A1
• Filed: 04/28/1998
• Published: 03/21/2002
• Est. Priority Date: 04/28/1998
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: GRILL, ALFRED, SAENGER, KATHERINE LYNN, CALLEGARI, ALESSANDRO, JAHNES, CHRISTOPHER VINCENT, BABICH, KATHERINA, PATEL, VISHNUBHAI VITTHALBHAI, COHEN, STEPHEN ALAN, PURUSHOTHAMAN, SAMPATH
• Granted Patent: US 6,448,655 B1
• Time in Patent Office: Days
• US Class Current: 257/758
• CPC Class Codes: H01L 21/0212 the material being fluoro carbon compounds, e.g.(CFx) n, (CHxFy) n or polytetrafluoroethylene
• CPC Class Codes: H01L 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/02348 treatment by exposure to UV light
• CPC Class Codes: H01L 21/31058 of organic layers
• CPC Class Codes: H01L 21/3127 Layers comprising fluoro (hydro)carbon compounds, e.g. polytetrafluoroethylene
• CPC Class Codes: H01L 21/31629 Deposition of halogen doped silicon oxide, e.g. fluorine doped silicon oxide
• CPC Class Codes: H01L 21/76814 post-treatment or after-treatment, e.g. cleaning or removal of oxides on underlying conductors
• CPC Class Codes: H01L 21/76825 by exposing the layer to particle radiation, e.g. ion implantation, irradiation with UV light or electrons etc. plasma treatment H01L21/76826
• CPC Class Codes: H01L 21/76828 thermal treatment
• CPC Class Codes: H01L 21/76829 characterised by the formation of thin functional dielectric layers, e.g. dielectric etch-stop, barrier, capping or liner layers
• CPC Class Codes: H01L 21/76831 in via holes or trenches, e.g. non-conductive sidewall liners
• CPC Class Codes: H01L 21/76832 Multiple layers
• CPC Class Codes: H01L 23/5329 Insulating materials
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A method for providing regions of substantially lower fluorine content in a fluorine containing dielectric is described incorporating exposing a region to ultraviolet radiation and annealing at an elevated temperature to remove partially disrupted fluorine from the region. The invention overcomes the problem of fluorine from a fluorine containing dielectric reacting with other materials while maintaining a bulk dielectric material of sufficiently high or original fluorine content to maintain an effective low dielectric constant in semiconductor chip wiring interconnect structures.

Claims

1. An interconnect structure comprising:

one or more layers of conductive wiring patterns electrically connected by conductive vias;

one or more layers of fluorine-containing dielectric (FCD) between at least some of said conductive wiring patterns;

said FCD modified so that at least some interfaces of said FCD with other materials in said interconnect structure are provided with a near-interface region that extends from said FCD interface into said FCD and has a substantially lower fluorine content.

2. A structure according to claim 1 wherein said FCD is selected from the group consisting of fluorinated diamond like carbon (FDLC);

FDLC with additives selected from the group consisting of H, Si, Ge, O, and N;

fluorinated silicon oxide (FSO);

fluorinated silicate glass (FSG);

organo-inorganic dielectrics containing fluorine; and

organic dielectrics containing fluorine.

3. A structure according to claim 1 wherein said near-interface region of substantially lower fluorine content has a thickness less than ½

of the respective FCD layer thickness so as to have minimal effect on the low dielectric constant of said FCD layer.

4. A structure according to claim 2 wherein the said FCD layer thickness is between 100 nm and 5000 nm.

5. A structure according to claim 4 wherein the said FCD layer thickness is more preferably between 300 nm and 1200 nm.

6. A structure according to claim 3 wherein the said near-interface region of substantially lower fluorine content is between 5 nm to 300 nm in thickness.

7. A structure according to claim 6 wherein the said near-interface region of substantially lower fluorine content is more preferably between 10 nm and 200 nm in thickness.

8. The interconnect structure of claim 1 further including an insulating cap layer.

9. A structure according to claim 8 wherein the said cap layer includes one or more films selected from the group consisting of amorphous silicon, silicon nitride, silicon oxide, silicon oxynitride, silicon carbide, silicon carbo-oxide and their hydrogen containing compounds, electrically insulating silicon-metal nitride, polyimide, diamond-like carbon, diamond-like carbon with additives selected from the group consisting of H, Si, Ge, O, and N, and combinations thereof.

10. A structure according to claim 8 wherein said conductive wiring pattern further includes a liner on at least the sidewalls and bottom of respective conductors of said conductive wiring pattern, said liner includes one or more films selected from the group comprising Cr, Ti, Ta, Nb, Zr, Mo, W, Al and electrically conductive oxides, oxynitrides, silicides, nitrides, metal silicon nitrides and combinations thereof.

11. A structure according to claim 1 further including a semiconductor integrated circuit substrate interconnected to said one or more layers of conductive wiring patterns.

12. A structure comprising a semiconductor packaging substrate with the interconnect structure of claim 1 disposed thereon to provide a means of interconnection and communication between microelectronic devices mounted thereon.

14. The method according to claim 13 wherein said ultraviolet radiation includes a wavelength in the range from 180 nm to 400 nm range to confine said disruption of the bonded fluorine to a near-interface region only.

15. The method according to claim 13 wherein the dose of said ultraviolet radiation is controlled to confine the disruption to the near-interface region only.

16. The method according to claim 13 wherein said step of exposing said region in said FCD layer to ultraviolet radiation includes providing an ambient selected from the group consisting of He, Ar, nitrogen, oxygen, nitrous oxide, forming gas, air, mixtures of said aforementioned ambients, and vacuum.

17. The method according to claim 13 wherein said elevated temperature is in the range from 200°

C. to 600°

C.

18. The method according to claim 13 wherein said elevated temperature is in the range from 300°

C. and 500°

C.

19. The method according to claim 13 wherein the said FCD layer is a blanket film.

20. The method according to claim 13 wherein the said FCD layer is prepatterned to possess trenches, vias or both prior to said step of exposing to ultraviolet radiation.

21. The method according to claim 13 wherein at least some of said step of annealing occurs concurrently with said step of exposing to ultraviolet radiation.

22. The method according to claim 20 wherein said step of exposing to ultraviolet radiation includes one or more of the steps of passing said radiation through a diffuser and rotating said substrate to vary the angle of incidence of radiation to the sidewalls and top surfaces of trenches and vias.

13. A method for providing a region of substantially lower fluorine content in a fluorine containing dielectric (FCD) layer comprising the steps of:

exposing said region in said FCD layer to ultraviolet radiation to at least partially disrupt at least some of the bonded fluorine in said region; and

annealing said FCD layer at an elevated temperature for a certain duration to liberate at least some of said at least partially disrupted fluorine thereby making said region substantially lower in fluorine concentration.