Microwave plasma processing process and apparatus

- Fujitsu Limited

A microwave plasma processing process and apparatus useful in the fabrication of integrated circuit (IC) or similar semiconductor devices, wherein the object or material to be processed, such as a semiconductor wafer, is processed with plasma generated using microwaves transmitted through a microwave transmission window disposed perpendicular to an electric field of the progressive microwaves in the waveguide.

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Claims

1. A microwave plasma processing apparatus for processing a material, comprising:

a reaction gas source for supplying a reaction gas;
a microwave generator generating microwaves having a wavelength.lambda.;
a waveguide, connected with said microwave generator, having a rectangular prism shape with a longitudinal axis and side-walls extending in parallel to the longitudinal axis, said waveguide receiving the microwaves propagating in a first direction parallel to the side-walls and for transferring the microwaves along the longitudinal axis of said waveguide;
a dielectric window, formed of at least two rectangular elements parallel to each other, superposed over an opening in a first side-wall of said waveguide, for transmitting the microwaves therethrough to an exterior surface thereof, the distance between the two rectangular elements being.lambda.g/4, where.lambda.g is a wavelength of the microwaves in the waveguide;
a plasma processing chamber connected to said reaction gas source and formed adjacent to the first side-wall of said waveguide to entirely enclose the exterior surface of said dielectric window, said plasma processing chamber offset on the exterior of said waveguide from the first side-wall of said waveguide in a second direction perpendicular to the longitudinal axis of said waveguide, said plasma processing chamber receiving the microwaves transmitted through said dielectric window and the reaction gas supplied from said reaction gas source to generate plasma therein; and
a stage for holding the material to be processed thereon, said stage disposed in said plasma processing chamber with a top surface of said stage substantially in parallel with said dielectric window..Iadd.

2. A microwave plasma processing apparatus in which material is to be processed using microwaves received by said microwave plasma processing apparatus, comprising:

a reactor for plasma processing therein, having a stage for holding the material to be processed;
a waveguide for transferring the microwaves in a propagating direction within the waveguide; and
a dielectric window, having first and second surfaces substantially parallel with the propagating direction of the microwaves adjacent said dielectric window, said first surface formed coplanar with an inner surface of said waveguide and said second surface forming part of an inner surface of said reactor..Iaddend..Iadd.3. A microwave plasma processing apparatus according to claim 2, wherein said dielectric window comprises insulating material, selected from at least one of silica and ceramic and alumina..Iaddend..Iadd.4. A microwave plasma processing apparatus according to claim 2,
further comprising a microwave transmitter, disposed adjacent said reactor, to propagate microwaves in the direction of propagating microwaves, said microwave transmitter having a first dielectric constant,
wherein said reactor has an interior with a second dielectric constant, and
wherein said dielectric window comprises a material having a third dielectric constant with a value between the first and second dielectric

constants..Iaddend..Iadd.5. A microwave plasma processing apparatus according to claim 4, wherein said dielectric window comprises material selected from a group of silica and ceramic..Iaddend..Iadd.6. A microwave plasma processing apparatus according to claim 2, wherein said dielectric window comprises a disc-shaped element..Iaddend..Iadd.7. A microwave plasma processing apparatus according to claim 2, wherein said dielectric window comprises plural windows, each of which has a size small enough to prevent arising breakage in said plasma processing..Iaddend..Iadd.8. A microwave plasma processing apparatus according to claim 7, wherein each

of said plural windows is made of alumina..Iaddend..Iadd.9. A microwave plasma processing apparatus according to claim 2, wherein said reactor further includes a reactive gas inlet and an exhaust gas outlet..Iaddend..Iadd.10. A microwave plasma processing apparatus according to claim 2, wherein the surface of the material to be processed has dimensions smaller than said dielectric window..Iaddend..Iadd.11. A microwave plasma processing apparatus according to claim 2, wherein the microwaves have a wavelength.lambda.,

wherein said microwave plasma processing apparatus further comprises a microwave transmitter, disposed adjacent said reactor, to propagate microwaves in the direction of propagating microwaves, and
wherein said stage has a top surface supporting the material to be processed and separated from an opposing wall of said microwave transmitter opposite said dielectric window by a distance of less than.lambda./2 during processing of the material..Iaddend..Iadd.12. A microwave plasma processing apparatus according to claim 2, further comprising a microwave transmitter, disposed adjacent said reactor, propagating microwaves in the direction of propagating microwaves and having a height, measured perpendicular to said dielectric window, gradually decreasing from a first value above said dielectric window to a second value at an end wall of said microwave transmitter downstream from said dielectric window..Iaddend..Iadd.13. A microwave plasma processing apparatus according to claim 2, further comprising:
a microwave transmitter, disposed adjacent said reactor, to propagate microwaves in the direction of propagating microwaves; and
a holder, supporting said dielectric window, replaceably fitted to said microwave transmitter..Iaddend..Iadd.14. A method for processing a material by plasma, comprising:
placing the material in a chamber having a dielectric window disposed in substantially the same plane as an inner surface of a waveguide; and
introducing microwaves via the waveguide along a first direction, substantially parallel to the inner surface of the waveguide and along the dielectric window, so that the plasma is generated in the chamber..Iaddend..Iadd.15. A microwave plasma processing method according to claim 14, wherein the dielectric window comprises insulating material, selected from at least one of silica and ceramic and

alumina..Iaddend..Iadd.16. A microwave plasma processing method according to claim 14,

further comprising transmitting the microwaves within a microwave transmitter in a direction of microwave propagation,
wherein the microwave transmitter and the reactor have interiors with first and second dielectric constants, respectively, and
wherein the dielectric window comprises a material having a third dielectric constant with a value between the first and second dielectric constants..Iaddend..Iadd.17. A microwave plasma processing method according to claim 16, wherein the dielectric window comprises material selected from a group of silica and ceramic..Iaddend..Iadd.18. A microwave plasma processing method according to claim 14, wherein the dielectric window comprises disc-shaped element..Iaddend..Iadd.19. A microwave plasma processing method according to claim 14, wherein the dielectric window comprises plural windows, each of which has a size small enough to prevent arising breakage in said plasma processing..Iaddend..Iadd.20. A microwave plasma processing method according to claim 19, wherein each of the plural

windows is made of alumina..Iaddend..Iadd.21. A microwave plasma processing method according to claim 14, wherein the reactor includes a reactive gas inlet and an exhaust gas outlet..Iaddend..Iadd.22. A microwave plasma processing method according to claim 14,

further comprising the step of transmitting the microwaves within a microwave transmitter in a direction of microwave propagation, and
wherein the microwaves have a wavelength.lambda., and the stage has a top surface supporting the material to be processed and separated from an opposing wall of the microwave transmitter opposite the dielectric window by a distance of less than.lambda./2 during said generating of the plasma..Iaddend..Iadd.23. A microwave plasma processing method according to claim 14,
further comprising the step of transmitting the microwaves within a microwave transmitter in a direction of microwave propagation, and
wherein the microwave transmitter has a height, measured perpendicular to the dielectric window, gradually decreasing from a first value above the dielectric window to a second value at an end wall of the microwave

transmitter downstream from the dielectric window..Iaddend..Iadd.24. A method for fabricating an integrated circuit semiconductor device, comprising:

transmitting microwaves within a microwave transmitter having an inner surface in a plane substantially parallel to a direction of microwave propagation;
disposing on a stage inside a reactor a semiconductor wafer having a surface substantially parallel to the direction of microwave propagation, with at least one of photoresist films to be removed from and protective layers to be etched off the surface of the semiconductor wafer;
reducing pressure in the reactor sufficiently to permit generation of plasma; and
generating the plasma by transmitting the microwaves through a dielectric window, having a first surface in substantially the plane of the inner surface of the microwave transmitter and thereby, parallel to the direction of microwave propagation adjacent the dielectric window, without altering the direction of microwave propagation in the microwave transmitter..Iaddend..Iadd.25. A microwave plasma processing method according to claim 24, further comprising cooling the material to be processed on the stage using a cooler, disposed below the stage, during at least said generating of the plasma..Iaddend..Iadd.26. A microwave plasma processing apparatus for processing material therein, comprising:
a reactor for plasma processing therein, having a stage for holding the material to be processed;
a waveguide for transferring microwaves; and
a dielectric window, disposed between said reactor and said waveguide in substantially the same plane as an inner surface of said waveguide and thereby substantially parallel with a direction of propagation of the

microwaves adjacent the dielectric window..Iaddend..Iadd.27. An apparatus for processing a material by plasma comprising:

a chamber having a dielectric window and a stage for placing the material;
a generator for generating microwaves; and
a waveguide for introducing the microwaves from the generator to the chamber, wherein the dielectric window is disposed in substantially the same plane as an inner surface of said waveguide and thereby substantially parallel to a direction along which the microwaves propagate adjacent the dielectric window so that the plasma is generated in said chamber..Iaddend..Iadd.28. A method for processing a material by plasma, comprising:
placing the material in a chamber having a dielectric window; and
introducing a microwave along a waveguide in a first direction adjacent the dielectric window substantially in parallel with an outer surface of the dielectric window disposed in substantially the same plane as an inner surface of the waveguide, so that the plasma is generated in the

chamber..Iaddend..Iadd.29. A microwave plasma processing method for processing a material with microwave generated plasma, comprising:

disposing the material to be processed on a stage inside a reactor, and positioning the stage facing a dielectric window formed as a part of the reactor; and
introducing microwaves along a waveguide having an inner surface in a plane, the dielectric window being disposed with an outer surface substantially in the plane of the inner surface of the waveguide, with the microwaves thereby propagating adjacent the dielectric window in a direction parallel to the dielectric window, so as to generate plasma between the dielectric window and the stage..Iaddend..Iadd.30. A microwave plasma processing apparatus to process material therein, comprising:
a microwave transmitter to propagate microwaves in a direction of microwave propagation inside containment walls, each having an inner surface;
a reactor having a stage to hold the material to be processed with a surface of the material substantially parallel to the direction of microwave propagation; and
a dielectric window, disposed with a first surface in substantially a same plane as the inner surface of one of the containment walls of the microwave transmitter and thereby substantially parallel to the direction of microwave propagation adjacent the dielectric window, and a second surface substantially parallel to the first surface, to provide a pressure seal between said microwave transmitter and said reactor enabling

generation of a plasma inside said reactor..Iaddend..Iadd.31. A microwave plasma processing apparatus in which material is to be processed therein, comprising:

a reactor for plasma processing therein, having a stage for holding the material to be processed;
a waveguide for transferring microwaves; and
a dielectric window, disposed so as to be part of a surface of said reactor and be substantially on the same plane as an inner surface of said waveguide, and thereby substantially parallel with a direction of propagating microwaves..Iaddend.
Referenced Cited
U.S. Patent Documents
4101411 July 18, 1978 Suzuki et al.
4245154 January 13, 1981 Uehara et al.
4265730 May 5, 1981 Hirose et al.
4298419 November 3, 1981 Suzuki et al.
4316791 February 23, 1982 Taillet
4330384 May 18, 1982 Okudaira et al.
4339326 July 13, 1982 Hirose et al.
4431473 February 14, 1984 Okano et al.
4462863 July 31, 1984 Nishmatsu et al.
4512868 April 23, 1985 Fujimura
4563240 January 7, 1986 Shibata et al.
Foreign Patent Documents
2716592 October 1977 DEX
61-4177 February 1986 JPX
Other references
  • European Search Report, The Hague, Feb. 10, 1988. Kraus, John D., Electromagnetics, 1973 pp. 482-485.
Patent History
Patent number: RE36224
Type: Grant
Filed: Nov 15, 1996
Date of Patent: Jun 8, 1999
Assignee: Fujitsu Limited (Kanagawa)
Inventors: Shuzo Fujimura (Chiba), Toshimasa Kisa (Miyazaki), Yasunari Motoki (Kita-kyushu)
Primary Examiner: Nam Nguyen
Assistant Examiner: Steven H. Versteeg
Law Firm: Staas & Halsey
Application Number: 8/749,654