US5399871A — Plasma flood system for the reduction of charging…

Claim 1

Independent Claim 141 words

An electron flood system for neutralizing positive charge buildup on a substrate during implantation of ions in the substrate, comprising: an electron confinement tube axially receiving and passing an ion beam to a substrate; a plasma generation chamber containing a gas for forming a plasma containing low energy electrons and having an exit aperture in communication with an open of the electron confinement tube to pass the low energy electrons into the tube to join the ion beam passing therethrough; and means for negatively biasing the electron confinement tube relative to the substrate to negatively shield the chamber, to control the passage of the low energy electrons into the electron confinement tube, and to contain and intensify the flow of the low energy electrons within and along the ion beam to the substrate to thereby neutralize positive charges on the substrate.

Claim 2

Dependent Claim 141 words

An electron flood system for neutralizing positive charge buildup on a substrate during implantation of ions in the substrate, comprising: an electron confinement tube axially receiving and passing an ion beam to a substrate; a plasma generation chamber containing a gas for forming a plasma containing low energy electrons and having an exit aperture in communication with an open of the electron confinement tube to pass the low energy electrons into the tube to join the ion beam passing therethrough; and means for negatively biasing the electron confinement tube relative to the substrate to negatively shield the chamber, to control the passage of the low energy electrons into the electron confinement tube, and to contain and intensify the flow of the low energy electrons within and along the ion beam to the substrate to thereby neutralize positive charges on the substrate.

Claim 3

Dependent Claim 39 words

The system of claim 1 further comprising first magnetic means adjacent to the chamber for generating a magnetic field to enhance a generation of the low energy electrons in the plasma and their passage into the electron containment tube.

Claim 4

Dependent Claim 39 words

The system of claim 2 wherein the first magnetic means includes a plurality of magnets around the chamber for generating magnetic fields sufficient to promote production of the low energy electrons and their passage into the electron containment tube.

Claim 5

Dependent Claim 28 words

The system of claim 2 further comprising second magnetic means comprises one or more axially extending arrays of magnets of alternating polarity spaced around the electron containment tube.

Claim 6

Dependent Claim 21 words

The system of claim 1 wherein the exit aperture comprises a nozzle extending from the chamber into the electron containment tube.

Claim 7

Dependent Claim 41 words

The system of claim 1, wherein said electron confinement tube is negatively biased with respect to said chamber and wherein a portion of said chamber surrounding said exit aperture is shielded from said ion by said negatively biased electron confinement tube.

Claim 8

Dependent Claim 25 words

The system of claim 1, wherein said low energy electrons passed into said confinement tube have a median energy level of less than 5 eV.

Claim 9

Dependent Claim 20 words

The system of claim 1, wherein said plasma generation chamber further comprises a filament thermionically emitting said low energy electrons.

Claim 10

Dependent Claim 16 words

The system of claim 8, wherein said confinement tube is negatively biased relative to said filament.

Claim 11

Dependent Claim 71 words

An electron flood system for use in the implantation of ions in a semiconductor substrate, comprising: a low energy electron source; and an electron confinement tube for receiving and passing an ion beam to a semiconductor substrate and including an inlet for receiving electrons from the low energy electron source, a portion of said electron confinement tube adjacent said electron source being negatively biased relative to said low energy electron source.

Claim 12

Dependent Claim 71 words

An electron flood system for use in the implantation of ions in a semiconductor substrate, comprising: a low energy electron source; and an electron confinement tube for receiving and passing an ion beam to a semiconductor substrate and including an inlet for receiving electrons from the low energy electron source, a portion of said electron confinement tube adjacent said electron source being negatively biased relative to said low energy electron source.

Claim 13

Dependent Claim 29 words

The system of claim 10, wherein said low energy electron source comprises a filament thermionically emitting said electrons and said confinement tube is negatively biased relative to said filament.

Claim 14

Dependent Claim 25 words

The system of claim 11, wherein said electrons emitted from the low energy electron source have a median energy level of less than 5 eV.

Claim 15

Dependent Claim 63 words

The system of claim 10, wherein said low energy electron source contains a plasma and further comprising first magnetic means for enhancing production of the low energy electrons within and passage thereof through the inlet with the plasma into the electron containment tube to flow with the ion beam to the semiconductor substrate to affect a neutralization of positive charge on the substrate.

Claim 16

Dependent Claim 63 words

The system of claim 10, wherein said low energy electron source is included within a chamber positively biased relative to said electron confinement tube and having a nozzle penetrating through said inlet of said electron confinement tube, said portion of said negatively biased electron confinement tube surrounding said nozzle and overlying a portion of said positively biased chamber facing said electron confinement tube.

Claim 17

Dependent Claim 16 words

The system of claim 14, wherein said chamber contains a plasma containing said low energy electrons.

Claim 18

Dependent Claim 63 words

The system of claim 10, wherein the low energy electron source contains a plasma and further comprising first magnetic means for enhancing production of the low energy electrons within and passage thereof through the inlet with the plasma into the electron confinement tube to flow with the ion beam to the semiconductor substrate to affect a neutralization of positive charge on the substrate.

Claim 19

Dependent Claim 130 words

A plasma flood system for use in the implantation of ions in a semiconductor substrate, comprising: a plasma source for forming a plasma containing low energy electrons; an electron confinement tube is negatively biased relative to said semiconductor substrate for receiving and passing an ion beam to the semiconductor substrate and including an inlet for receiving the plasma from the plasma source; first magnetic means for enhancing production of the low energy electrons within and passage thereof through the inlet with the plasma into the electron confinement tube to flow with the ion beam to the semiconductor substrate to affect a neutralization of positive charge on the substrate; and second magnetic means along the tube for generating magnetic fields which enhance electron confinement along the tube to the semiconductor substrate.

Claim 20

Dependent Claim 130 words

A plasma flood system for use in the implantation of ions in a semiconductor substrate, comprising: a plasma source for forming a plasma containing low energy electrons; an electron confinement tube is negatively biased relative to said semiconductor substrate for receiving and passing an ion beam to the semiconductor substrate and including an inlet for receiving the plasma from the plasma source; first magnetic means for enhancing production of the low energy electrons within and passage thereof through the inlet with the plasma into the electron confinement tube to flow with the ion beam to the semiconductor substrate to affect a neutralization of positive charge on the substrate; and second magnetic means along the tube for generating magnetic fields which enhance electron confinement along the tube to the semiconductor substrate.

Claim 21

Dependent Claim 26 words

The system of claim 17 wherein the second magnetic means comprises one or more axially extending arrays of magnets of alternating polarity spaced around the tube.

Claim 22

Dependent Claim 101 words

An electron flood system used in an ion implantation system for implanting ions from an ion beam into a substrate, comprising: a guide tube extending along an axis, receiving said ion beam along said axis, and delivering along said axis said ion beam to said substrate and said guide tube is negatively biased relative to said substrate; an electron generator generating electrons and delivering said electrons to said ion beam obliquely to said axis; and first magnetic means along said guide tube adjacent to said electron generator for generating magnetic fields confining said electrons to a vicinity of said ion beam.

Claim 23

Dependent Claim 101 words

An electron flood system used in an ion implantation system for implanting ions from an ion beam into a substrate, comprising: a guide tube extending along an axis, receiving said ion beam along said axis, and delivering along said axis said ion beam to said substrate and said guide tube is negatively biased relative to said substrate; an electron generator generating electrons and delivering said electrons to said ion beam obliquely to said axis; and first magnetic means along said guide tube adjacent to said electron generator for generating magnetic fields confining said electrons to a vicinity of said ion beam.

Claim 24

Dependent Claim 48 words

The system of claim 19, wherein said electron generator comprises a plasma generator chamber including a gas forming a plasma therewithin and a filament thermionically emitting electrons into said plasma, said chamber having a nozzle smaller than a cross section of said chamber communicating with said guide tube.

Claim 25

Dependent Claim 23 words

The system of claim 20, further comprising second magnetic means along walls of said chamber for generating magnetic fields parallel to said walls.

Claim 26

Dependent Claim 63 words

An electron flood system used in an ion beam system processing a substrate, comprising: a holder of a substrate; a tube axially passing an ion beam therethrough and negatively biased relative to said holder; and an electron source communicating through a first aperture in a side wall of said tube to supply electrons emitted from said electron source therethrough to said ion beam.

Claim 27

Dependent Claim 63 words

An electron flood system used in an ion beam system processing a substrate, comprising: a holder of a substrate; a tube axially passing an ion beam therethrough and negatively biased relative to said holder; and an electron source communicating through a first aperture in a side wall of said tube to supply electrons emitted from said electron source therethrough to said ion beam.

Claim 28

Dependent Claim 47 words

An electron flood system of claim 22, wherein said electron source comprises a plasma source having a wall including a second aperture communicating with said first aperture and a filament contained therein, and wherein said wall of the plasma source is positively biased relative to said filament.

Claim 29

Dependent Claim 17 words

An electron flood system of claim 23, wherein said tube is negatively biased relative to said filament.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1998-03-20	1998-09-19	1999-03-21	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2002-03-20	2002-09-19	2003-03-21	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2006-03-20	2006-09-19	2007-03-21	$7700.00	Window Closed / Lapsed

Plasma flood system for the reduction of charging of wafers during ion implantation

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag