US4751393A — Dose measurement and uniformity monitoring system…

Claim 1

Independent Claim 110 words

Apparatus for determining ion dose and ion dose uniformity of an ion beam scanned over a target plane in response to a scanning signal, comprising: means for sensing the ion beam received at a plurality of different sensing locations and providing a single beam signal representative of the total ion beam current received at all of the sensing locations; means for integrating said single beam signal with respect to time to determine ion dose; and uniformity monitoring means responsive to said scanning signal and said single beam signal for determining the component of said beam current received at each of said different sensing locations and determining ion dose uniformity therefrom.

Claim 2

Dependent Claim 110 words

Apparatus for determining ion dose and ion dose uniformity of an ion beam scanned over a target plane in response to a scanning signal, comprising: means for sensing the ion beam received at a plurality of different sensing locations and providing a single beam signal representative of the total ion beam current received at all of the sensing locations; means for integrating said single beam signal with respect to time to determine ion dose; and uniformity monitoring means responsive to said scanning signal and said single beam signal for determining the component of said beam current received at each of said different sensing locations and determining ion dose uniformity therefrom.

Claim 3

Dependent Claim 35 words

Apparatus as defined in claim 1 wherein said sensing means comprises a Faraday cup at each of the different sensing locations, said Faraday cups having a common electrical connection which carries said single beam signal.

Claim 4

Dependent Claim 26 words

Apparatus as defined in claim 2 including four Faraday cups equally spaced about a beam axis in a sensing plane substantially perpendicular to the beam axis.

Claim 5

Dependent Claim 104 words

Apparatus as defined in claim 1 wherein said sensing means includes a mask assembly positioned in the path of said ion beam in a plane substantially perpendicular to the beam, said mask assembly including a mask plate having a first aperture for passage of the ion beam to the target plane and a plurality of beam sensing apertures positioned at each of said sensing locations around said first aperture, and an annular Faraday cup positioned behind said mask plate in alignment with said sensing apertures for sensing the total beam current received through all of said sensing apertures and providing said single beam signal.

Claim 6

Dependent Claim 39 words

Apparatus as defined in claim 4 wherein said first aperture in said mask plate is circular and coaxial with the beam axis and wherein said plurality comprises four sensing apertures equally spaced around the periphery of said first aperture.

Claim 7

Dependent Claim 38 words

Apparatus as defined in claim 4 wherein said annular Faraday cup has a diameter larger than said first aperture and is coaxial with said first aperture, said Faraday cup having beam collection holes aligned with said sensing apertures.

Claim 8

Dependent Claim 61 words

Apparatus as defined in claim 4 further including a graphite aperture plate mounted between said mask plate and said annular Faraday cup, said aperture plate including accurately dimensioned apertures aligned with the sensing apertures in said mask plate, and at least one bias electrode mounted between each aperture in said aperture plate and said annular Faraday cup to suppress secondary electrons.

Claim 9

Dependent Claim 40 words

Apparatus as defined in claim 1 wherein said uniformity monitoring means includes demultiplexing means responsive to said scanning signal for identifying the sensing location of each beam current component and for switching said beam signal in response to said determination.

Claim 10

Dependent Claim 40 words

Apparatus as defined in claim 8 when said ion beam is scanned in a two-dimensional raster scan pattern by x-scan and y-scan signals and said demultiplexing means includes means for identifying the quadrant of each component of said beam current.

Claim 11

Dependent Claim 99 words

Apparatus as defined in claim 9 wherein said demultiplexing means includes averaging means for determining the average value of said x-scan signal and said y-scan signal, comparator means for comparing average values of said x-scan and y-scan signals with the respective instantaneous values thereof, decoder means responsive to the outputs of said comparator means for determining the quadrant in which the ion beam is located at any instant of time, and switching means responsive to the outputs of said decoder means for switching said beam signal to prescribed outputs depending on the sensing location at which it was received.

Claim 12

Dependent Claim 50 words

Apparatus is defined in claim 10 wherein said uniformity monitoring means further includes means responsive to the outputs of said demultiplexer means for determining the deviation of the beam signal at each of said different sensing locations from a reference value, said deviation providing a measure of ion dose uniformity.

Claim 13

Dependent Claim 137 words

Apparatus for determining ion dose and ion dose uniformity of a scanned ion beam comprising: means for generating and directing an ion beam along an axis; means for scanning said ion beam in two dimensions perpendicualr to said axis over a target plane in response to x-scan and y-scan beam scanning signals; means for sensing the ion beam received at a plurality of different sensing locations and providing a single beam signal representative of the total ion beam current received at all of the sensing locations; means for integrating said single beam signal with respect to time to determine ion dose; and uniformity monitoring means responsive to said scanning signals and said single beam signal for determining the component of said beam current received at each of said different sensing locations and determining ion dose uniformity therefrom.

Claim 14

Dependent Claim 137 words

Apparatus for determining ion dose and ion dose uniformity of a scanned ion beam comprising: means for generating and directing an ion beam along an axis; means for scanning said ion beam in two dimensions perpendicualr to said axis over a target plane in response to x-scan and y-scan beam scanning signals; means for sensing the ion beam received at a plurality of different sensing locations and providing a single beam signal representative of the total ion beam current received at all of the sensing locations; means for integrating said single beam signal with respect to time to determine ion dose; and uniformity monitoring means responsive to said scanning signals and said single beam signal for determining the component of said beam current received at each of said different sensing locations and determining ion dose uniformity therefrom.

Claim 15

Dependent Claim 98 words

Apparatus as defined in claim 12 wherein said means for sensing includes a mask assembly positioned between said means for generating and said target plane, said mask assembly comprising a mask plate having a relatively large first aperture therethrough for passage of the ion beam to said target plane and a plurality of smaller sensing apertures positioned around said target aperture, and an annular Faraday cup positioned behind said mask plate around said first aperture in alignment with said sensing apertures for sensing the beam current passing through all of said sensing apertures and providing said beam signal.

Claim 16

Dependent Claim 39 words

Apparatus as defined in claim 13 wherein said first aperture in said mask plate is circular and coaxial with the beam axis and wherein said plurality comprises four sensing apertures equally spaced around the periphery of said first aperture.

Claim 17

Dependent Claim 38 words

Apparatus as defined in claim 13 wherein said annular Faraday cup has a diameter larger than said first aperture and is coaxial with said first aperture, said Faraday cup having beam collection holes aligned with said sensing apertures.

Claim 18

Dependent Claim 61 words

Apparatus as defined in claim 13 further including a graphite aperture plate mounted between said mask plate and said annular Faraday cup, said aperture plate including accurately dimensioned apertures aligned with the sensing apertures in said mask plate, and at least one bias electrode mounted between each aperture in said aperture plate and said annular Faraday cup to suppress secondary electrons.

Claim 19

Dependent Claim 42 words

Apparatus as defined in claim 12 wherein said uniformity monitoring means includes demultiplexing means responsive to said scanning signal for identifying the sensing location of each component of said beam current and for switching said beam signal in response to said determination.

Claim 20

Dependent Claim 40 words

Apparatus as defined in claim 17 wherein said ion beam is scanned in a two-dimensional raster scan pattern by x-scan and y-scan signals and said demultiplexing means including means for identifying the quadrant of each component of said beam current.

Claim 21

Dependent Claim 99 words

Apparatus as defined in claim 18 wherein said demultiplexing means includes averaging means for determining the average value of said x-scan signal and said y-scan signal, comparator means for comparing average values of said x-scan and y-scan signals with the respective instantaneous values thereof, decoder means responsive to the outputs of said comparator means for determining the quadrant in which the ion beam is located at any instant of time, and switching means responsive to the outputs of said decoder means for switching said beam signal to prescribed outputs depending on the sensing location at which it was received.

Claim 22

Independent Claim 107 words

A method for determining ion dose and ion dose uniformity of an ion beam scanned over a target plane in response to a scanning signal, said method comprising the steps of: sensing the ion beam received at a plurality of different sensing locations and providing a single beam signal representative of the total ion beam current received at all of the sensing locations; integrating said beam signal with respect to time to determine ion dose; and utilizing said scanning signal and said single beam signal for determining the component of said beam current received at each of said different sensing locations and determining ion dose uniformity therefrom.

Claim 23

Independent Claim 107 words

A method for determining ion dose and ion dose uniformity of an ion beam scanned over a target plane in response to a scanning signal, said method comprising the steps of: sensing the ion beam received at a plurality of different sensing locations and providing a single beam signal representative of the total ion beam current received at all of the sensing locations; integrating said beam signal with respect to time to determine ion dose; and utilizing said scanning signal and said single beam signal for determining the component of said beam current received at each of said different sensing locations and determining ion dose uniformity therefrom.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1991-06-14	1991-12-14	1992-06-14	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1995-06-14	1995-12-14	1996-06-14	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1999-06-14	1999-12-14	2000-06-14	$7700.00	Window Closed / Lapsed

Dose measurement and uniformity monitoring system for ion implantation

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