Microwave or UHF plasma improved apparatus

• US 4,630,566 A
• Filed: 11/15/1985
• Issued: 12/23/1986
• Est. Priority Date: 08/16/1984
• Status: Expired due to Term

• Current Assignee: The Board of Trustees of Michigan State University (Michigan State University)
• Original Assignee: The Board of Trustees of Michigan State University (Michigan State University)
• Inventors: Asmussen, Jes, Reinhard, Donnie K.
• Primary Examiner(s): Page, Thurman K.
• Application Number:
  US06/798,309
• Time in Patent Office: 403 Days
• Field of Search: 118/50.1, 118/723, 118/620, 118/729, 118/730, 118/621, 118/623, 118/503, 315/111.41, 315/111.81
• US Class Current: 118/50.1
• CPC Class Codes: H01J 27/16 using high-frequency excitation, e.g. microwave excitation
• CPC Class Codes: H01J 37/32192 Microwave generated discharge H01J37/32357, H01J37/32366, H01J37/32394, H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32256 Tuning means
• CPC Class Codes: H01J 37/32284 Means for controlling or selecting resonance mode
• CPC Class Codes: H01J 37/32678 Electron cyclotron resonance

Abstract

A method for etching or chemically treating a surface of an article utilizing a radio frequency wave ion generating apparatus which provides a thin disk shaped plasma is described. The plasma disks can have a relatively large diameter (on the order of magnitude 50 centimeters). The plasma disks can be created without using a static magnetic field. The radio frequency waves are preferably microwaves or UHF. The method is particularly useful for ion or free radical irradiation of the surface provided in the plasma or for irradiation of the surface by ions accelerated outside a cavity containing the plasma. Disk plasmas are created over a wide pressure range (10^-4 Torr to 1 atmosphere) and are highly ionized at low pressures. An apparatus adapted for treating a surface of an article with ions from a plasma is also described. The method and apparatus are preferably used for treating a surface forming part of an integrated circuit.

Claims

1. An ion generating apparatus for treating a surface which comprises:

(a) a plasma source employing a radio frequency, including UHF or microwave, wave coupler which is metallic and in the shape of a hollow cavity and which is excited in one or more of its TE or TM modes of resonance and optionally including a static magnetic field surrounding the plasma source which aids in coupling a electron cyclotron resonance and aids in confining the ions in the coupler, wherein the plasma is maintained at a reduced pressure in operation and wherein the ion source apparatus includes an electrically insulated chamber having a central longitudinal axis mounted in closely spaced relationship to an area of the coupler;

(b) gas supply means for providing a gas which is ionized to form the plasma in the insulated chamber, wherein the radio frequency wave applied to the coupler creates and maintains the plasma in the shape of an elongate plasma disk perpendicular to and surrounding the central longitudinal axis in the chamber;

(c) movable metal plate means in the cavity mounted perpendicular to the axis and movable towards and away from the chamber;

(d) a movable probe connected to and extending inside the coupler for coupling the radio frequency waves to the coupler, wherein movement of the plate means and the probe in the coupler achieves the selected TE or TM mode of resonance of the radio frequency wave in the coupler and varies the resonance of the mode;

(e) ion attracting means for attachment to the surface to be treated for attracting ions from the plasma to the surface by means of a suitable voltage potential; and

(f) a platform supporting the surface to be treated and electrically insulated from the ion attracting means.

2. The apparatus of claim 1 wherein the platform is mounted on a hollow tube through which a wire is inserted and electrically connected to the surface, wherein the wire provides the voltage potential, wherein holding brackets are attached to the tube and wherein releasable means are provided on the holding brackets for clamping the tube and thus positioning the platform relative to the plasma.

3. The apparatus of claim 2 wherein the platform is a conductive metal and wherein an insulator is provided between the platform and the article to be treated.

4. The apparatus of claim 1 wherein the platform is movable into and out of the plasma.