Method and system for focusing and registration in electron beam projection microfabrication

Claim 3

In a method for focusing and registration of an electron beam projection system including a source of an electron beam, a projection mask having a unique pattern of registration electron beam windows therein, an adjustable focal length condenser lens system located between said electron source and said projection mask including electron lenses for collecting said electron beam from said source and directing said beam onto said projection mask, a target wafer having a unique registration marks on the surface thereof, a projection lens system located between said projection mask and said target wafer for collecting electron beams passing through said projection mask and directing them onto said target wafer, a deflection system located between said source and said mask for scanning said electron beam across said mask, said deflection system cooperating with said condenser lens system to scan the focus of said electron beam across the plane of said projection mask at one of said registration windows and said projection lens system operating to focus the portion of said electron beam passing through a said window in said mask onto the surface of said target wafer, and electronic detection means for sensing the image projected through said mask onto said wafer, the improvement comprising, focusing said electron beam into a pencil point beam upon a point upon said projection mask, scanning said pencil point beam to hit a registration window in said mask, viewing said detection means to determine whether said electron beam is directed towards said registration mark on the surface of said target wafer, and adjusting the position until said beam is directed towards said mark, and then changing the focus of said condenser lens system to adjust said beam to flood said projection mask and to project through all of the windows therein upon said target wafer.

Claim 4

In a method for focusing and registration of an electron beam projection system including a source of an electron beam, a projection mask having a unique pattern of registration electron beam windows therein, an adjustable focal length condenser lens system located between said electron source and said projection mask including electron lenses for collecting said electron beam from said source and directing said beam onto said projection mask, a target wafer having a unique registration marks on the surface thereof, a projection lens system located between said projection mask and said target wafer for collecting electron beams passing through said projection mask and directing them onto said target wafer, a deflection system located between said source and said mask for scanning said electron beam across said mask, said deflection system cooperating with said condenser lens system to scan the focus of said electron beam across the plane of said projection mask at one of said registration windows and said projection lens system operating to focus the portion of said electron beam passing through a said window in said mask onto the surface of said target wafer, and electronic detection means for sensing the image projected through said mask onto said wafer, the improvement comprising, focusing said electron beam into a pencil point beam upon a point upon said projection mask, scanning said pencil point beam to hit a registration window in said mask, viewing said detection means to determine whether said electron beam is directed towards said registration mark on the surface of said target wafer, and adjusting the position until said beam is directed towards said mark, and then changing the focus of said condenser lens system to adjust said beam to flood said projection mask and to project through all of the windows therein upon said target wafer.

Claim 7

A method in accordance with claim 3 wherein said first means is adjusted to focus said beam upon said mask by adjusting the control of said first means to yield a focused image of the scanned portion of said mask upon said display, and adjusting said means for projection to focus said beam passing through said mask upon said target, prior to adjusting scale and alignment of said projection.

Claim 8

A focusing and registration system for an electron beam projection system comprising: a source of an electron beam, a projection mask having a unique pattern of registration electron beam windows therein, a condenser lens system located between said electron source and said projection mask including electron lenses for collecting said electron beam from said source and focusing said beam onto a point on said projection mask, a target wafer having a unique registration mark on the surface thereof, a projection lens system located between said projection mask and said target wafer for collecting electron beams passing through said projection mask and directing them onto said target wafer, a deflection system located between said source and said mask for scanning said electron beam across said mask, said deflection system cooperating with said condenser lens system to scan the focus of said electron beam across the plane of said projection mask at one of said registration windows and said projection lens system operating to focus the portion of said electron beam passing through a registration window in said mask onto the surface of said target wafer, and electronic detection means for sensing the image projected through said mask onto said wafer.

Claim 9

A focusing and registration system for an electron beam projection system comprising: a source of an electron beam, a projection mask having a unique pattern of registration electron beam windows therein, a condenser lens system located between said electron source and said projection mask including electron lenses for collecting said electron beam from said source and focusing said beam onto a point on said projection mask, a target wafer having a unique registration mark on the surface thereof, a projection lens system located between said projection mask and said target wafer for collecting electron beams passing through said projection mask and directing them onto said target wafer, a deflection system located between said source and said mask for scanning said electron beam across said mask, said deflection system cooperating with said condenser lens system to scan the focus of said electron beam across the plane of said projection mask at one of said registration windows and said projection lens system operating to focus the portion of said electron beam passing through a registration window in said mask onto the surface of said target wafer, and electronic detection means for sensing the image projected through said mask onto said wafer.

Claim 10

A focusing and registration system according to claim 5 wherein said projection mask has holes therein in a predetermined pattern, one of said holes being a unique registration hole.

Claim 11

A focusing and registration system according to claim 5 further including a projection aperture located in said projection lens system and where a first and second pair of deflection elements are located in said condenser lens system in a plane conjugate to the plane of said projection aperture through all projection lenses between said aperture and said mask and at least one condenser lens.

Claim 12

A focusing and registration system according to claim 5 wherein said detection means is an electron detector responsive to electrons scattered from the surface of or collected by said target wafer.

Claim 13

A focusing and registration system according to claim 5 wherein said condenser lens system includes a first magnetic condenser lens, a second condenser lens and a final condenser lens and wherein said deflection system is located between said second condenser lens and said final condenser lens.

Claim 14

A focusing and registration system according to claim 5 wherein said projection lens system includes a first magnetic projection lens and a final magnetic projection lens, said aperture being located between said first and final projection lenses and said projection mask being located between said condenser lens system and said first projection lens.

Claim 15

A focusing and registration system according to claim 5 wherein said first and second pair of deflection elements are first and second deflection coils arranged orthogonally with respect to each other.

Claim 16

A focusing and registration system according to claim 6 wherein said registration hole in said projection mask and said registration mark on said target wafer have the same geometrical shapes.

Claim 17

A focusing and registration system according to claim 6 wherein said registration hole in said projection mask and said registration mark on said target wafer are dissimilar in geometric shape.

Claim 18

A focusing and registration system according to claim 8 wherein said electron detection means includes an electron detector responsive to electrons from the surface of said target wafer and a video display means connected to said electron detector for visually displaying the projected image of said registration window in said projection mask on said target wafer and the image of said registration mark on the surface of said target wafer.

Claim 19

A focusing system for an electron beam projection system comprising: a source of an electron beam, a projection mask having a unique pattern of windows therein, a condenser lens system located between said electron source and said projection mask including an electron lens for collecting said electron beam from said source and focusing said beam onto a point on said projection mask, a target, a projection lens system including at least one lens and an aperture located between said projection mask and said target for collecting the portion of said electron beam passing through said projection mask and directing it onto said target, a deflection system for scanning said electron beam across said mask, including deflection elements located between said source and said projection mask, said deflection system cooperating with said condenser lens system to scan the focus of said electron beam across the plane of said projection mask across at least one of said windows and said projection lens system operating to focus said electron beam passing through said window in said mask onto a point on the surface of said target.

Claim 20

A focusing system for an electron beam projection system comprising: a source of an electron beam, a projection mask having a unique pattern of windows therein, a condenser lens system located between said electron source and said projection mask including an electron lens for collecting said electron beam from said source and focusing said beam onto a point on said projection mask, a target, a projection lens system including at least one lens and an aperture located between said projection mask and said target for collecting the portion of said electron beam passing through said projection mask and directing it onto said target, a deflection system for scanning said electron beam across said mask, including deflection elements located between said source and said projection mask, said deflection system cooperating with said condenser lens system to scan the focus of said electron beam across the plane of said projection mask across at least one of said windows and said projection lens system operating to focus said electron beam passing through said window in said mask onto a point on the surface of said target.

Claim 21

A focusing and registration system for an electron beam electrical circuit manufacturing system comprising: a source of an electron beam, a projection mask having a unique registration pattern of windows therein, a condenser lens system located between said electron source and said projection mask including electron lenses for collecting said electron beam from said source and focusing said beam onto a point on said projection mask, a target electrical circuit material, a projection lens system including at least one lens and an aperture located between said projection mask and said target wafer for collecting said electron beam passing through said projection mask and directing said beam onto said target material, a deflection system for scanning said electron beam across said mask located in said condenser lens system in a plane conjugate to the plane of said aperture through all projection lenses between said aperture and said mask and at least one condenser lens, said deflection system cooperating with said condenser lens system to focus and scan said electron beam in the plane of said projection mask across at least one of said registration windows and operating with said projection lens system to focus the portion of said electron beam passing through said window in said mask onto a point on the surface of said target material.

Claim 22

A focusing and registration system for an electron beam electrical circuit manufacturing system comprising: a source of an electron beam, a projection mask having a unique registration pattern of windows therein, a condenser lens system located between said electron source and said projection mask including electron lenses for collecting said electron beam from said source and focusing said beam onto a point on said projection mask, a target electrical circuit material, a projection lens system including at least one lens and an aperture located between said projection mask and said target wafer for collecting said electron beam passing through said projection mask and directing said beam onto said target material, a deflection system for scanning said electron beam across said mask located in said condenser lens system in a plane conjugate to the plane of said aperture through all projection lenses between said aperture and said mask and at least one condenser lens, said deflection system cooperating with said condenser lens system to focus and scan said electron beam in the plane of said projection mask across at least one of said registration windows and operating with said projection lens system to focus the portion of said electron beam passing through said window in said mask onto a point on the surface of said target material.

Claim 23

An electron beam wafer exposure system including, a target, a source of an electron beam, a projection mask for said target, means for focusing said beam on said mask, means for scanning said focused beam across said mask, means for projecting radiation from said beam in the image formed by said mask onto said target, means for sensing beam radiation projected onto said target, means for displaying a scanned input having a radiation input connected to receive the output of said means for sensing for display and having position inputs for receiving scanning signals, means for providing scanning signals having outputs connected to drive said means for scanning and said position inputs of said means for displaying in synchronism, whereby radiation projected onto said target through said mask is displayed upon said display.

Claim 24

An electron beam wafer exposure system including, a target, a source of an electron beam, a projection mask for said target, means for focusing said beam on said mask, means for scanning said focused beam across said mask, means for projecting radiation from said beam in the image formed by said mask onto said target, means for sensing beam radiation projected onto said target, means for displaying a scanned input having a radiation input connected to receive the output of said means for sensing for display and having position inputs for receiving scanning signals, means for providing scanning signals having outputs connected to drive said means for scanning and said position inputs of said means for displaying in synchronism, whereby radiation projected onto said target through said mask is displayed upon said display.

Claim 25

In a method for focusing and registration of an electron beam projection system including a source of an electron beam, a projection mask having a unique pattern of registration electron beam windows therein, an adjustable focal length condenser lens system located between said electron source and said projection mask including electron lenses for collecting said electron beam from said source and directing said beam onto said projection mask, a target wafer having a unique registration mark on the surface thereof, a projection lens system located between said projection mask and said target wafer for collecting electron beams passing through said projection mask and directing them onto said target wafer, a deflection system located between said source and said mask for scanning said electron beam across said mask, said deflection system cooperating with said condenser lens system to scan the focus of said electron beam across the plane of said projection mask at one of said registration windows and said projection lens system operating to focus the portion of said electron beam passing through a said window in said mask onto the surface of said target wafer, and electronic detection means for sensing the image projected through said mask onto said wafer, the improvement comprising, focusing said electron beam into a pencil point beam upon a point upon said projection mask, scanning said pencil point beam to hit a registration window in said mask, viewing said detection means to determine whether said electron beam is directed towards said registration mark on the surface of said target wafer, and adjusting the deflection of the beam until said beam is directed through said window towards said mark, adjusting power to said condenser lens system to focus said mask as presented upon said display; adjusting power to said projection lens system to focus the image of said target wafer upon said display; adjusting the scale of the projection of said mask shown upon said display to match the spacing of the images of said registration windows with corresponding registration marks upon said target as shown upon said display; adjusting the alignment of the projection through of said windows upon said marks; and then changing the focus of said condenser lens system to adjust said beam to flood said projection mask and to project through all of the windows therein upon said target wafer.

Claim 26

In a method for focusing and registration of an electron beam projection system including a source of an electron beam, a projection mask having a unique pattern of registration electron beam windows therein, an adjustable focal length condenser lens system located between said electron source and said projection mask including electron lenses for collecting said electron beam from said source and directing said beam onto said projection mask, a target wafer having a unique registration mark on the surface thereof, a projection lens system located between said projection mask and said target wafer for collecting electron beams passing through said projection mask and directing them onto said target wafer, a deflection system located between said source and said mask for scanning said electron beam across said mask, said deflection system cooperating with said condenser lens system to scan the focus of said electron beam across the plane of said projection mask at one of said registration windows and said projection lens system operating to focus the portion of said electron beam passing through a said window in said mask onto the surface of said target wafer, and electronic detection means for sensing the image projected through said mask onto said wafer, the improvement comprising, focusing said electron beam into a pencil point beam upon a point upon said projection mask, scanning said pencil point beam to hit a registration window in said mask, viewing said detection means to determine whether said electron beam is directed towards said registration mark on the surface of said target wafer, and adjusting the deflection of the beam until said beam is directed through said window towards said mark, adjusting power to said condenser lens system to focus said mask as presented upon said display; adjusting power to said projection lens system to focus the image of said target wafer upon said display; adjusting the scale of the projection of said mask shown upon said display to match the spacing of the images of said registration windows with corresponding registration marks upon said target as shown upon said display; adjusting the alignment of the projection through of said windows upon said marks; and then changing the focus of said condenser lens system to adjust said beam to flood said projection mask and to project through all of the windows therein upon said target wafer.