US5136171A — Charge neutralization apparatus for ion implantat…

Claim 1

Independent Claim 139 words

Apparatus for neutralization of a workpiece in a system wherein a beam of positive ions is applied to the workpiece, comprising: an electron source for generating an electron beam having a relatively large cross-sectional area; and p1 means for transporting said electron beam from said electron source to said workpiece so as to provide substantially uniform distribution of said electron beam over said workpiece, said means for transporting comprising magnetic means for generating a magnetic field along a prescribed electron beam path between said electron source and said workpiece for guiding said electron beam to said workpiece, said magnetic field having an axial component parallel to said electron beam path along substantially the entire length of said electron beam path, and a supply of positive ions along said electron beam path for space charge neutralization of said electron beam.

Claim 2

Dependent Claim 139 words

Apparatus for neutralization of a workpiece in a system wherein a beam of positive ions is applied to the workpiece, comprising: an electron source for generating an electron beam having a relatively large cross-sectional area; and p1 means for transporting said electron beam from said electron source to said workpiece so as to provide substantially uniform distribution of said electron beam over said workpiece, said means for transporting comprising magnetic means for generating a magnetic field along a prescribed electron beam path between said electron source and said workpiece for guiding said electron beam to said workpiece, said magnetic field having an axial component parallel to said electron beam path along substantially the entire length of said electron beam path, and a supply of positive ions along said electron beam path for space charge neutralization of said electron beam.

Claim 3

Dependent Claim 31 words

Apparatus as defined in claim 1 wherein said magnetic means includes a steering coil extending generally between said electron source and said workpiece for generating said axial component of magnetic field.

Claim 4

Dependent Claim 49 words

Apparatus as defined in claim 1 wherein said magnetic means comprises a steering coil including a generally helical conductor surrounding said electron beam and means for providing an electrical current through said steering coil for generating an axial component of said magnetic field generally parallel to said beam path.

Claim 5

Dependent Claim 48 words

Apparatus as defined in claim 3 wherein said steering coil includes a first section and a second section, said steering coil having an opening between said first and second sections for receiving said ion beam, said electron beam and said ion beam being coincident in said second section.

Claim 6

Dependent Claim 26 words

Apparatus as defined in claim 4 wherein said steering coil extends from a region adjacent to said electron source to a region adjacent to said workpiece.

Claim 7

Dependent Claim 39 words

Apparatus as defined in claim 4 wherein said magnetic means further includes means for generating a transverse component of said magnetic field in an elbow region between said first and second sections that is perpendicular to said electron beam.

Claim 8

Dependent Claim 28 words

Apparatus as defined in claim 6 wherein said means for generating a tranverse components of said magnetic field comprises coil means positioned above and below said elbow region.

Claim 9

Dependent Claim 61 words

Apparatus as defined in claim 7 wherein said magnetic means further includes first and second trim coils in said elbow region between said first and second sections for modifying the axial component of said magnetic field, said first trim coil having a plane perpendicular to said ion beam and said second trim coil having a plane parallel to said ion beam.

Claim 10

Dependent Claim 32 words

Apparatus as defined in claim 7 wherein said magnetic means further includes a magnetically permeable element between said workpiece and said electron source for completing a magnetic circuit with said steering coil.

Claim 11

Dependent Claim 21 words

Apparatus as defined in claim 1 wherein the electrons in said electron beam have energies of 30 electron volts or less.

Claim 12

Dependent Claim 25 words

Apparatus as defined in claim 1 wherein said electron source comprises a large area cathode and means for extracting low energy electrons from said cathode.

Claim 13

Dependent Claim 12 words

Apparatus as defined in claim 11 wherein said cathode comprises lanthanum hexaboride.

Claim 14

Dependent Claim 25 words

Apparatus as defined in claim 10 wherein said magnetic field has an axial component in the direction of said electron beam less than 100 gauss.

Claim 15

Dependent Claim 22 words

Apparatus as defined in claim 12 wherein said cathode has an area that is approximately equal to the area of the workpiece.

Claim 16

Independent Claim 143 words

A method for neutralization of a workpiece in a system wherein a beam of positive ions is applied to the workpiece, said method comprising the steps of: generating an electron beam having a relatively large cross-sectional area with an electron source; and transporting said electron beam from said electron source to said workpiece so as to provide substantially uniform distribution of said electron beam over said workpiece, the step of transporting said electron beam including generating a magnetic field along a prescribed electron beam path between said electron source and said workpiece for guiding said electron beam to said workpiece, said magnetic field having an axial component parallel to said electron beam path along substantially the entire length of said electron beam path, and providing a supply of positive ions along said electron beam path for space charge neutralization of said electron beam.

Claim 17

Independent Claim 143 words

A method for neutralization of a workpiece in a system wherein a beam of positive ions is applied to the workpiece, said method comprising the steps of: generating an electron beam having a relatively large cross-sectional area with an electron source; and transporting said electron beam from said electron source to said workpiece so as to provide substantially uniform distribution of said electron beam over said workpiece, the step of transporting said electron beam including generating a magnetic field along a prescribed electron beam path between said electron source and said workpiece for guiding said electron beam to said workpiece, said magnetic field having an axial component parallel to said electron beam path along substantially the entire length of said electron beam path, and providing a supply of positive ions along said electron beam path for space charge neutralization of said electron beam.

Claim 18

Dependent Claim 37 words

A method as defined in claim 15 wherein the step of generating a magnetic field includes providing a steering coil extending generally between said electron source and said workpiece for generating said axial component of magnetic field.

Claim 19

Dependent Claim 69 words

A method as defined in claim 16 wherein said electron beam path includes a first section and a second section that are generally perpendicular to each other, said first and second sections intersecting in an elbow region, and wherein the step of generating a magnetic field further includes the step of generating a transverse component of said magnetic field perpendicular to said electron beam path in said elbow region.

Claim 20

Dependent Claim 38 words

A method as defined in claim 15 wherein the step of generating an electron beam includes extracting low energy electrons from a large area lanthanum hexaboride cathode with an extraction grid positioned in close proximity to said cathode.

Claim 21

Dependent Claim 139 words

Ion implantation apparatus comprising: means for generating a beam of positive ions for treatment of a semiconductor wafer; an electron source for generating an electron beam having a relatively large cross-sectional area; and means for transporting said electron beam from said electron source to said semiconductor wafer so as to provide substantially uniform distribution of said electron beam over said semiconductor wafer, said means for transporting comprising magnetic means for generating a magnetic field along a prescribed electron beam path between said electron source and said semiconductor wafer for guiding said electron beam to said semiconductor wafer, said magnetic field having an axial component parallel to said electron beam path along substantially the entire length of said electron beam path, and a supply of positive ions along said electron beam path for space charge neutralization of said electron beam.

Claim 22

Dependent Claim 139 words

Ion implantation apparatus comprising: means for generating a beam of positive ions for treatment of a semiconductor wafer; an electron source for generating an electron beam having a relatively large cross-sectional area; and means for transporting said electron beam from said electron source to said semiconductor wafer so as to provide substantially uniform distribution of said electron beam over said semiconductor wafer, said means for transporting comprising magnetic means for generating a magnetic field along a prescribed electron beam path between said electron source and said semiconductor wafer for guiding said electron beam to said semiconductor wafer, said magnetic field having an axial component parallel to said electron beam path along substantially the entire length of said electron beam path, and a supply of positive ions along said electron beam path for space charge neutralization of said electron beam.

Claim 23

Dependent Claim 51 words

Ion implantation apparatus as defined in claim 19 wherein said magnetic means comprises a steering coil including a generally helical conductor surrounding said electron beam and means for providing an electrical current through said steering coil for generating said axial component of said magnetic field generally parallel to said beam path.

Claim 24

Dependent Claim 50 words

Ion implantation apparatus as defined in claim 20 wherein said steering coil includes a first section and a second section, said steering coil having an opening between said first and second sections for receiving said ion beam, said electron beam and said ion beam being coincident in said second section.

Claim 25

Dependent Claim 28 words

Ion implantation apparatus as defined in claim 21 wherein said steering coil extends from a region adjacent to said electron source to a region adjacent to said workpiece.

Claim 26

Dependent Claim 41 words

Ion implantation apparatus as defined in claim 21 wherein said magnetic means further includes means for generating a transverse component of said magnetic field in an elbow region between said first and second sections that is perpendicular to said electron beam.

Claim 27

Dependent Claim 30 words

Ion implantation apparatus as defined in claim 23 wherein said means for generating a transverse component of said magnetic field comprises coil means positioned above and below said elbow region.

Claim 28

Dependent Claim 27 words

Ion implantation apparatus as defined in claim 19 wherein said electron source comprises a large area cathode and means for extracting low energy electrons from said cathode.

Claim 29

Dependent Claim 14 words

Ion implantation apparatus as defined in claim 25 wherein said cathode comprises lanthanum hexaboride.

Claim 30

Dependent Claim 181 words

Ion implantation apparatus comprising: means for generating an ion beam of positive ions and for directing the ion beam along an ion beam path to a semiconductor wafer; an electron source for generating an electron beam having a relatively large cross-sectional area; means for transporting said electron beam from said electron source to said semiconductor wafer so as to provide substantially uniform distribution of said electron beam over said semiconductor wafer, said means for transporting comprising magnetic means for generating a magnetic field along a prescribed electron beam path between said electron source and said semiconductor wafer for guiding said electron beam to said semiconductor wafer, said magnetic field having an axial component parallel to said electron beam path along substantially the entire length of said electron beam path, and a supply of positive ions along said electron beam path for space charge neutralization of said electron beam, a vacuum chamber enclosing said ion beam path, said electron beam path and said semiconductor wafer, said vacuum chamber defining a high vacuum region; and means for vacuum pumping of said vacuum chamber.

Claim 31

Dependent Claim 181 words

Ion implantation apparatus comprising: means for generating an ion beam of positive ions and for directing the ion beam along an ion beam path to a semiconductor wafer; an electron source for generating an electron beam having a relatively large cross-sectional area; means for transporting said electron beam from said electron source to said semiconductor wafer so as to provide substantially uniform distribution of said electron beam over said semiconductor wafer, said means for transporting comprising magnetic means for generating a magnetic field along a prescribed electron beam path between said electron source and said semiconductor wafer for guiding said electron beam to said semiconductor wafer, said magnetic field having an axial component parallel to said electron beam path along substantially the entire length of said electron beam path, and a supply of positive ions along said electron beam path for space charge neutralization of said electron beam, a vacuum chamber enclosing said ion beam path, said electron beam path and said semiconductor wafer, said vacuum chamber defining a high vacuum region; and means for vacuum pumping of said vacuum chamber.

Claim 32

Dependent Claim 35 words

Ion implantation apparatus as defined in claim 27 wherein said electron source is remotely located from said ion beam path, and further including means for selectively isolating said electron source from said high vacuum region.

Claim 33

Dependent Claim 31 words

Ion implantation apparatus as defined in claim 28 wherein said means for selectively isolating said electron source includes vacuum valve means positioned between said electron source and said high vacuum region.

Claim 34

Dependent Claim 36 words

Ion implantation apparatus as defined in claim 29 wherein said magnetic means comprises a steering coil including a generally helical conductor surrounding said electron beam and means for providing an electrical current through said steering coil.

Claim 35

Dependent Claim 33 words

Ion implantation apparatus as defined in claim 27 wherein said ion beam and said electron beam intersect at an angle in a range from slightly greater than 0° to slightly less than 180°.

Claim 36

Dependent Claim 31 words

Ion implantation apparatus as defined in claim 27 wherein said ion beam and said electron beam intersect at an angle in a range from about 90° to slightly less than 180°.

Claim 37

Dependent Claim 159 words

Ion implantation apparatus comprising: means for generating an ion beam of positive ions and for directing the ion beam along an ion beam path to a semiconductor wafer; an electron source for generating an electron beam; magnetic means for generating a magnetic field along a prescribed electron beam path between said electron source and said semiconductor wafer for guiding said electron beam to said semiconductor wafer, said magnetic field having an axial component parallel to said electron beam path along substantially the entire length of said electron beam path; a vacuum chamber enclosing said ion beam path, said electron beam path and said semiconductor wafer, said vacuum chamber defining a high vacuum region; and means for vacuum pumping of said vacuum chamber, said ion beam and said electron beam intersecting at an angle in a range from greater than 90° to slightly less than 180° such that contaminants from the electron source are directed away from the semiconductor wafer.

Claim 38

Dependent Claim 159 words

Ion implantation apparatus comprising: means for generating an ion beam of positive ions and for directing the ion beam along an ion beam path to a semiconductor wafer; an electron source for generating an electron beam; magnetic means for generating a magnetic field along a prescribed electron beam path between said electron source and said semiconductor wafer for guiding said electron beam to said semiconductor wafer, said magnetic field having an axial component parallel to said electron beam path along substantially the entire length of said electron beam path; a vacuum chamber enclosing said ion beam path, said electron beam path and said semiconductor wafer, said vacuum chamber defining a high vacuum region; and means for vacuum pumping of said vacuum chamber, said ion beam and said electron beam intersecting at an angle in a range from greater than 90° to slightly less than 180° such that contaminants from the electron source are directed away from the semiconductor wafer.

Claim 39

Dependent Claim 36 words

Ion implantation apparatus as defined in claim 27 further including cooling means disposed along said electron beam path for removing thermal energy generated by said electron source and for condensing materials emitted by said electron source.

Claim 40

Dependent Claim 36 words

Ion implantation apparatus as defined in claim 34 wherein said magnetic means comprises a steering coil including a generally helical conductor surrounding said electron beam and means for providing an electrical current through said steering coil.

Claim 41

Dependent Claim 32 words

Ion implantation apparatus as defined in claim 35 wherein said steering coil comprises a tubular conductor and wherein said cooling means comprises means for circulating a cooling fluid through said tubular conductor.

Claim 42

Dependent Claim 28 words

Ion implantation apparatus as defined in claim 36 wherein cooling means further comprises a nonmagnetic tube located within said steering coil and thermally connected to said steering coil.

Claim 43

Dependent Claim 39 words

Ion implantation apparatus as defined in claim 27 further including a Faraday charge measurement system positioned between said means for generating an ion beam and said semiconductor wafer, said electron beam being guided into said Faraday charge measurement system.

Claim 44

Dependent Claim 36 words

Ion implantation apparatus as defined in claim 38 wherein said magnetic means comprises a steering coil including a generally helical conductor surrounding said electron beam and means for providing an electrical current through said steering coil.

Claim 45

Dependent Claim 36 words

Ion implantation apparatus as defined in claim 39 further including cooling means disposed along said electron beam path for removing thermal energy generated by said electron source and for condensing materials emitted by said electron source.

Claim 46

Dependent Claim 49 words

Ion implantation apparatus as defined in claim 40 wherein said cooling means comprises a nonmagnetic, thermally conductive tube located within said steering coil and thermally connected to said steering coil, said thermally conductive tube extending from a region adjacent to said electron source to said Faraday charge measurement system.

Claim 47

Dependent Claim 32 words

Ion implantation apparatus as defined in claim 41 wherein said steering coil comprises a tubular conductor and wherein said cooling means comprises means for circulating a cooling fluid through said tubular conductor.

Claim 48

Dependent Claim 27 words

Ion implantation apparatus as defined in claim 27 wherein said electron source comprises a large area cathode and means for extracting low energy electrons from said cathode.

Claim 49

Dependent Claim 14 words

Ion implantation apparatus as defined in claim 43 wherein said cathode comprises lanthanum hexaboride.

Claim 50

Dependent Claim 49 words

Ion implantation apparatus as defined in claim 27 wherein said magnetic means further includes means for generating a tranverse component of said magnetic field in an elbow region where said electron beam intersects said ion beam, said transverse component being perpendicular to said electron beam and said ion beam.

Claim 51

Dependent Claim 31 words

Ion implantation apparatus as defined in claim 45 wherein said means for generating a transverse component of said magnetic field comprises Helmholtz coils positioned on opposite sides of said ion beam.

Claim 52

Dependent Claim 27 words

Ion implantation apparatus as defined in claim 43 wherein said large area cathode has an area that is approximately equal to the area of the semiconductor wafer.

Claim 53

Dependent Claim 24 words

Ion implantation apparatus as defined in claim 27 wherein said electron source generates an electron beam having a current of up to 100 milliamps.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1995-08-04	1996-02-03	1996-08-04	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1999-08-04	2000-02-03	2000-08-04	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2003-08-04	2004-02-03	2004-08-04	$7700.00	Window Closed / Lapsed

Charge neutralization apparatus for ion implantation system

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