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US 5,149,976 AGranted
Charged particle beam pattern generation apparatus and method
AssigneeHughes Aircraft Company
InventorDale M. Sipma
Life of this patent
Estimating the term…
Abstract
A pattern control system and method for a charged particle beam such as a focused ion beam (FIB) (20) or electron beam writes beam patterns on a pixel-by-pixel (56) basis. Respective dwell times and beam blanking states are specified for each separate pixel location (56), enabling the creation of arbitrary patterns and various implantation gradients. Pixel commands are generated by a central processing unit (CPU) (104), which can be relieved by hardware pattern generators (FIG. 10) for frequently used patterns. The system also includes improvements in stigmation control, fiducial mark recognition and the reconciliation of the beam and target coordinate systems.
Claims32
A charged particle beam system comprising:
- means for generating a charged particle beam;
- beam deflecting means for deflecting the beam across a target;
- a control system for the beam which includes means for controlling the beam deflecting means to deflect the beam through a sequence of successive pixel locations, and to dwell at each of said pixel locations for controlled dwell times, and
- means for adjusting the beam dwell time for different pixel locations,
- wherein said means for controlling the beam dwell time includes means for establishing an initial dwell time for the first pixel in a sequence of pixels, and for adjusting the beam dwell time by a set of predetermined increments for successive pixels in said sequence to establish a predetermined dwell time gradient over said sequence.
2 more elements
A charged particle beam system comprising:
- means for generating a charged particle beam;
- beam deflecting means for deflecting the beam across a target;
- a control system for the beam which includes means for controlling the beam deflecting means to deflect the beam through a sequence of successive pixel locations, and to dwell at each of said pixel locations for controlled dwell times, said means for controlling the beam deflecting means including means for adjusting the amount of beam deflection between successive pixel locations in a sequence of pixels and means for establishing an initial beam deflection between initial pixels in a sequence of pixels, and for adjusting the beam deflection by a set of predetermined increments for successive pixels in said sequence to establish a predetermined beam deflection gradient over said sequence.
A charged particle beam system comprising:
- means for generating a charged particle beam;
- beam deflecting means for deflecting the beam across a target;
- a control system for the beam which includes means for controlling the beam deflecting means to deflect the beam through a sequence of successive pixel locations, and to dwell at each of said pixel locations for controlled dwell times,
- said beam deflecting means comprising an octopole deflector having eight deflection plates distributed generally symmetrically around the beam, with two opposed plates on an x-axis, two opposed plates on a y-axis perpendicular to the x-axis, two opposed plates on a +x,y-axis approximately 45.degree. to one side of the x-axis, and two opposed plates on a -x,y-axis approximately 45.degree. to the other side of the x-axis, further comprising stigmation control means for rounding elliptically shaped beams, said stigmation control means comprising means for applying voltage signals in the form of Acos2.theta., -Acos2.theta., Asin2.theta. and -Asin2.theta. to the x-axis, y-axis, +x,y-axis and -x,y-axis plates, respectively, where A is a constant representing the degree of beam ellipticity, and .theta. is the angle of the beam's major elliptical axis with respect to the x-axis.
1 more element
A charged particle beam system comprising:
- means for generating a charged particle beam;
- means for deflecting the beam across a target, and
- a control system for the beam which includes:
- means for controlling the beam deflecting means to perform pattern scanning through an arbitrary sequence of pixel locations, and to dwell at each of said pixel locations for controlled dwell times,
- fiducial mark recognition means for controlling said beam deflection means to execute multiple scans in pixelized patterns across a fiducial mark having opposed edges on a target in opposed directions,
- means for monitoring emissions from the target to detect the crossing of the fiducial mark edges during each scan and to generate signals in response thereto,
- means for compiling the locations of the detected crossings for opposed scans to derive a fiducial mark location which is generally independent of detection delays associated with scanning the fiducial mark in a single direction, and
- processing means for averaging said signals.
5 more elements
A method of exposing a surface to a charged particle beam comprising:
- generating a charged particle beam;
- generating a pattern of sequential pixel locations along the surface;
- directing the beam along the surface in accordance with said pattern of sequential pixel locations, and
- causing the beam to dwell at each of said pixel locations for controlled dwell times, wherein said beam dwell times are controlled by generating a pattern of beam dwell times corresponding to said pixel locations, and applying a dwell time to the beam at each pixel location in accordance with said pattern of beam dwell times, and wherein the beam dwell time is adjusted by a set of predetermined increments for successive pixels in a sequence of pixels to establish a predetermined dwell time gradient over said sequence.
1 more element
A method of exposing a surface to a charged particle beam, comprising:
- generating a charged particle beam;
- generating a pattern of sequential pixel locations along the surface;
- directing the beam along the surface in accordance with said pattern of sequential pixel locations, and
- causing the beam to dwell at each of said pixel locations for controlled dwell times,
- wherein an octopole deflector is used to direct the beam across the surface, the octopole deflector having eight deflection plates distributed generally symmetrically around the beam, with two opposed plates on an x-axis, two opposed plates on a y-axis perpendicular to the x-axis, two opposed plates on a +x,y-axis approximately 45.degree. to one side of the x-axis, and two opposed plates on a -x,y-axis approximately 45.degree. to the other side of the x-axis, further comprising the step of reducing the beam stigmation for elliptical beams by applying voltage signals in the form of Acos2.theta., -Acos2.theta., Asin2.theta. and -Asin2.theta. to the x-axis, y-axis, +x,y-axis and -x,y-axis plates, respectively, where A is a constant representing the degree of beam ellipticity, and .theta. is the angle of the beam's major elliptical axis with respect to the x-axis.
2 more elements
A method of exposing a surface to a charged particle beam, comprising
- generating a charged particle beam;
- generating a pattern of sequential pixel locations along the surface;
- pattern scanning with the beam along the surface in accordance with said pattern of pixel locations in arbitrary sequence, and
- causing the beam to dwell at each of said pixel locations for controlled dwell times, wherein said pattern of pixel locations is generated to direct the beam in multiple scans in pixelized patterns across a fiducial mark having opposed edges on the surface in opposed directions, further comprising the steps of monitoring emissions from the surface to detect the crossing the fiducial mark edges during each scan and generating signals in response thereto, and deriving the fiducial mark location from said opposed scans so that it is generally independent of detection delays associated with scanning the fiducial mark in a single direction, said step of deriving including averaging said signals.
1 more element
A method of exposing a surface to a charged particle beam, comprising:
- generating a charged particle beam;
- generating a pattern of sequential pixel locations along the surface;
- directing the beam along the surface in accordance with said pattern of sequential pixel locations, and
- causing the beam to dwell at each of said pixel locations for controlled dwell times, and
- further comprising the step of controlling the beam blanking state at each of said pixel locations,
- wherein the initial pixel location in said pattern is repeated at least once to provide sufficient time for the beam to move to said initial location, and the beam is blanked for all but the final repetition of said initial pixel location.
3 more elements
A method of exposing a surface to a charged particle beam, comprising:
- generating a charged particle beam;
- generating a pattern of sequential pixel locations along the surface;
- directing the beam along the surface in accordance with said pattern of sequential pixel locations, and
- causing the beam to dwell at each of said pixel locations for controlled dwell times, and
- further comprising the step of controlling the beam blanking state at each of said pixel locations,
- wherein the beam dwell time at the initial pixel location in said pattern is extended by a time sufficient to compensate for the beam transit time, and the beam is blanked a corresponding time prior to the end of its dwell time at the last pixel location in said pattern.
3 more elements
An ion implantation method comprising:
- moving a focused ion beam (FIB) between successive pixel locations on a substrate into which implantation is desired,
- allowing the FIB to dwell at said pixel locations for predetermined dwell times, and
- varying the spacing on the substrate between at least some of said successive pixel locations, wherein the spacing between successive pixel locations is progressively incremented to develop an implantation gradient along said locations.
An ion implantation method, comprising:
- moving a focused ion beam (FIB) between successive pixel locations on a substrate into which implantation is desired,
- controlling the FIB dwell time at each of said pixel locations, and
- varying the FIB dwell time among at least some of said pixel locations.
A method of reducing elliptical distortion of a charged particle beam traversing an octopole deflector having eight deflection plates distributed generally symmetrically around the beam with two opposed plates on an x-axis, two opposed plates on a y-axis perpendicular to the x-axis, two opposed plates on a +x,y-axis approximately 45.degree. to one side of the x-axis, and two opposed plates on a -x,y-axis approximately 45.degree. to the other side of the x-axis, comprising applying voltage signals in the form of Acos2.theta., -Acos2.theta., Asin2.theta. and -Asin2.theta. to the x-axis, the y-axis, the +x,y-axis and the -x,y-axis plates, respectively, where A is a constant representing the degree of beam ellipticity, and .theta. is the angle of the beam's major elliptical axis with respect to the x-axis.
A method of detecting the position of a fiducial mark having opposed edges on the surface of a substrate, comprising:
- directing a beam in multiple scans in pixelized patterns across the fiducial mark in opposed directions,
- monitoring emissions from the surface to detect the crossing of the fiducial mark edges during each scan and to generate signals in response thereto, and
- deriving the fiducial mark location from said opposed scans so that the location is generally independent of detection delays associated with scanning the fiducial mark in a single direction, said step of deriving including:
- averaging said signals using processing means to locate the center of the mark.
1 more element
Dependencies are inferred from the claim text.