Sputtering process and apparatus

• US 4,166,018 A
• Filed: 01/31/1974
• Issued: 08/28/1979
• Est. Priority Date: 01/31/1974
• Status: Expired due to Term

• Current Assignee: BOC Group Pty Limited (Linde Plc)
• Original Assignee: Airco, Inc.
• Inventors: Chapin, John S.
• Primary Examiner(s): Vertiz, O. R.
• Assistant Examiner(s): Langel, Wayne A.
• Application Number:
  US05/438,482
• Time in Patent Office: 2,035 Days
• Field of Search: 204/192, 204/298, 204/192 R
• US Class Current: 204/192.12
• CPC Class Codes: C23C 14/35 by application of a magnetic field, e.g. magnetron sputtering C23C14/3457 takes precedence
• CPC Class Codes: H01J 37/3408 Planar magnetron sputtering
• CPC Class Codes: H01J 37/3435 Target holders (includes backing plates and endblocks)
• CPC Class Codes: H01J 37/3441 Dark space shields
• CPC Class Codes: H01J 37/3458 Electromagnets in particular for cathodic sputtering apparatus electromagnets in general H01F7/06
• CPC Class Codes: H01J 37/3497 Temperature of target

Abstract

Sputtering apparatus is described in which a magnetic field is formed adjacent a planar sputtering surface, the field comprising arching lines of flux over a closed loop erosion region on the sputtering surface.

Claims

1. Apparatus for coating a substrate by sputtering comprising a cathode defining a substantially planar sputtering surface comprised of material to be sputtered, magnet means for producing a magnetic field having lines of flux which extend in a curve from said sputtering surface and return thereto to form an endless arch over a closed loop erosion region on said sputtering surface, an anode positioned to produce an accelerating electric field adjacent said sputtering surface for producing a glow discharge confined by said magnetic field to the region adjacent said sputtering surface and within said closed loop endless arch, said anode being outside the zone of glow discharge confinement and out of the path of travel of sputtered particles moving from the sputtering surface to a substrate, and means for connecting said cathode and said anode to a source of electrical potential.

2. Sputtering apparatus according to claim 1 wherein said closed loop erosion region has at least two parallel segments.

3. Sputtering apparatus according to claim 2 wherein said parallel segments are substantially longer than the remaining segments of said closed loop erosion region.

4. Sputtering apparatus according to claim 2 wherein said closed loop erosion region is in the outline of a rectangle.

5. Sputtering apparatus according to claim 1 wherein said magnet means comprise a magnetically permeable closed loop channel having its open side adjacent said cathode and containing an electrically conductive magnetizing coil.

6. Sputtering apparatus according to claim 1 including means for maintaining said cathode at a potential below ground and for maintaining said anode at a potential above ground.

7. In electric glow discharge sputtering apparatus for coating a substrate by the progressive disintegration of a cathode by positive ion bombardment in a low pressure environment, the improvement which comprises a cathode having a substantially planar disintegration surface, a magnet structure oriented with respect to said planar cathode to cause the magnetic flux lines emanating from such magnetic structure to project into the space adjacent the disintegration surface of the planar cathode and to intercept a finite closed loop portion of said surface to confine the glow discharge plasma to a closed loop region immediately adjacent the planar disintegration surface, and an anode outside the region of plasma confinement and out of the path of travel of sputtered particles moving from the sputtering surface to a substrate.

8. A high rate sputtering apparatus for coating a substrate with material sputtered from a substantially planar sputtering surface in a low pressure environment, comprising magnet means for maintaining a magnetic field having contiguous lines of magnetic flux which emerge from the sputtering surface, arc into the space adjacent to the sputtering surface and re-enter the sputtering surface, which magnetic flux arcs extend parallel to the sputtering surface in a configuration to form an endless magnetic tunnel overlying a closed loop portion of the sputtering surface;

a first electrode underlying the entire closed loop portion of the sputtering surface;

a second electrode in proximity to said first electrode but displaced from any straight line intersecting the said closed loop portion normal to the planar surface thereof; and

means for connecting said first and second electrodes to a source of electric potential to establish an electric field therebetween and create a glow discharge plasma which is confined by the interaction of said magnetic and electric fields to the region closely adjacent said closed loop portion of the sputtering surface and spaced from said second electrode whereby ions from the plasma impinge on said closed loop portion of the sputtering surface causing sputtered material to be transferred from the sputtering surface to the substrate substantially without transfer of sputtered material to said second electrode.

9. Cathode sputtering apparatus for operation within an evacuable enclosure for coating a substrate which is also contained within said enclosure, said apparatus comprising:

a cathode having a face of material to be sputtered;

magnetic means adjacent to the cathode and at a side thereof opposite from the face, said magnetic means including a pair of magnetic poles, at least one of which is elongated, and between which there are developed magnetic lines of force, at least some of said lines of force entering and leaving said face at spaced-apart intersections therewith, and including continuously arched segments extending between said intersections which are spaced from the face, said face together with said lines of force forming a boundary of a closed area in the plane of each of the respective lines of force thereby forming a tunnel-like path within which charged particles tend to be retained, and along which they tend to move;

an anode outside the said tunnel-like path in proximity to the cathode and removed from the path of travel of sputtered particles moving to the substrate, and connector means whereby said cathode and said anode can be connected to a source of electrical potential, said tunnel-like path being closed on itself whereby to form a continuous path without beginning or end, said face opening in a direction generally opposite from said side, and said path being a closed loop lying on a plane.

10. A sputtering apparatus for coating a substrate comprising:

a cathode of material to be sputtered having a substantially planar sputtering surface;

magnetic means for producing a magnetic field having lines of flux which extend from the sputtering surface, arc into the space adjacent the sputtering surface, and return to the sputtering surface so as to form an endless arch within which ionizing electrons are confined adjacent a closed loop erosion region on the sputtering surface, said magnetic means comprising a first pole piece which extends around a closed periphery adjacent the surface of the cathode opposite the sputtering surface and a second pole piece inside the closed periphery of the first pole piece.

an anode outside the arch and out of the path of sputtered material moving from the erosion region to the substrate; and

means for connecting the anode and cathode to a source of electrical potential which, when energized, produces an electric field adjacent the sputtering surface for accelerating ionized gas towards the cathode and ejecting material from the erosion region.

11. In a process utilizing a planar disintegration cathode for sputter coating a substrate supported in the path of travel of sputtered particles moving substantially normal to the planar disintegration surface the improvement which comprises increasing the cathode disintegration rate by confining the glow discharge plasma in an endless loop magnetic tunnel immediately adjacent the cathode surface and locating the anode outside the region of glow discharge plasma confinement and out of the path of travel of the sputtered particles from the disintegration surface to the substrate.