Laser pattern generating system
AssigneeTRE Semiconductor Equipment Corporation
InventorTheodore R. Whitney
Life of this patent
Estimating the term…
Abstract
In this laser pattern generator, plural laser beams are arranged in a closely spaced, noninterfering array. The beams are concurrently deflected across a region of the target surface by an acousto-optic deflector driven by a swept frequency drive signal. The target is moved perpendicular to the direction of deflection to reposition it for exposure during the next stroke of the beams. The extent of target offset in the direction of deflection is measured and used to control initiation of modulation during each deflection stroke, so that each portion of the generated pattern begins from a uniform reference line on the target. Pattern data is supplied to the beam modulators in accordance with data clock pulses the repetition rate of which is established by the rate of change of frequency of the deflector drive signal.
Claims43
In a laser pattern generating system, the improvement comprising:
- laser source means for providing a plurality of coaligned laser beams impinging in noninterfering, mutually closely spaced relationship on the surface of a target;
- deflector means for simultaneously deflecting said plurality of coaligned laser beams through a controllable range of angles across a portion of said surface while maintaining said closely spaced relationship;
- and
- modulation means, independent of said providing means for selectively, independently modulating said beams during said deflection so that said modulated, deflected beams form an image on said surface.
A method for generating a pattern on a target surface, said target being movable, said target surface havlng a photosensitive material thereon for exposure by laser radiation, comprising:
- storing information indicative of the pattern to be generated;
- generating a plurality of laser beams propagating in the same direction toward said target surface;
- modulating the intensity of each laser beam in accordance with said stored pattern information;
- simultaneously deflecting all of said modulated laser beams at a controlled rate, utilizing a single acousto-optic deflector, to expose selectively portions of said photosensitive material on said substrate, said deflecting and modulating steps being coordinated to generate a portion of said pattern;
- and
- moving said target relative to said laser beams and repeating said modulating and deflecting steps in coordination with said moving to generate additional contiguous portions of said pattern.
A system for generating integrated circuit or other patterns on a target surface having photosensitive material thereon, said target surface being located on a movable support, comprising:
- means for producing a plurality of laser beams for exposing said photosensitive material, said laser beams being aligned to propagate in the same direction towards said target surface and to impinge thereon in noninterfering mutually closely spaced relationship;
- deflecting means for repetitively angularly deflecting said plurality of laser beams through a controlled angular range;
- modulating means for concurrently modulating said laser beams during said deflection with information relating to a portion of said pattern, thereby to expose a corresponding region of said target surface to said portion of said pattern;
- positioning means for moving said support;
- and
- control means, coordinating operation of said deflecting, modulating and positioning means, for moving said support and enabling said modulation to expose contiguous regions of said target surface to correspondingly contiguous portions of said pattern during sequential deflections of said plural beams.
A control system for a laser pattern generator comprising:
- first means for repetitively sweeping a plurality of noninterfering, coaligned, mutually closely spaced modulated laser beams through a certain distance along a first direction on the surface of a target,
- second means for moving the target in a direction lateral to said first direction through a distance corresponding to the overall width of said plural beams in the time taken to complete each sweep, and for starting the next sequential sweep when said lateral movement is completed,
- third means for measuring the extent of positional offset of said target in the direction of said sweep introduced during said lateral movement, and
- modulation initiation means for advancing or delaying the initiation of modulation of said plural beams with pattern data by an amount corresponding to said measured positional offset,
- whereby contiguous sections of the pattern being generated begin along a uniform reference line on said target surface.
In a laser pattern generator in which one or more coaligned laser beams are used to expose a pattern onto a target surface, said beams being modulated with pattern data to form said pattern, the improvement comprising:
- deflector means for deflecting all of said beams through an angle determined by the frequency of a drive signal supplied thereto,
- a voltage controlled oscillator ramped to produce an output which sweeps repetitively over a controlled range of frequencies, said output being supplied to said deflector means as the drive signal therefor, and
- data clock means for deriving from said oscillator output a data clock signal for enabling the supply of pattern data for beam modulation during said beam deflection.
A laser pattern generator in which plural coaligned laser means are used to expose a pattern onto a target surface, said beams being modulated with pattern data to form said pattern, the improvement comprising:
- deflector means for deflecting all of said beams through an angle determined by the frequency of a drive signal supplied thereto,
- said plural coaligned laser beams being arrayed with each adjacent pair of beams having a spacing in the direction perpendicular to beam deflection which is less than the spacing at which interference between said pair of beams would occur, but being spaced apart in the direction of beam deflection by a sufficient offset distance so that such interference does not occur, and
- individual beam delay means for delaying the supply of modulating pattern data to individual beams by an amount corresponding to the offset distance of that beam in the direction of deflection.
A system for generating integrated circuit or other patterns on a target surface having photosensitive material thereon, said target surface being located on a movable supoport, comprising:
- means for producing a plurality of laser beams for exposing said photosensitive material, said laser beams being aligned to propagate in the same direction towards said target surface and to impinge thereon in noninterfering mutually closely spaced relationship,
- deflecting means for repetitively angularly deflecting said plurality of laser beams through a controlled angular range,
- modulating means for concurrently modulating said laser beams during said deflection with information relating to a portion of said pattern, thereby to expose a corresponding region of said target surface to said portion of said pattern;
- positioning means for moving said support;
- and
- control means, coordinating operation of said deflecting, modulating and positioning means, for moving said support and enabling said modulation to expose contiguous regions of said target surface to correspondingly contiguous portions of said pattern during sequential deflections of said plural beams, said control means including:
- a first means for sensing the position of said support along the direction perpendicular to the angular deflection of said laser beams, said first means providing a signal to said deflecting means to initiate an angular deflection of said laser beams when said support is appropriately positioned in said perpendicular direction for exposure of a portion of said pattern, and
- a second means for sensing the position of said support along the direction parallel to the angular deflection of said laser beams, said second means providing a signal indicative of the position of said support along said parallel direction, said signal causing modulation data representative of said portion of said pattern to be supplied to said modulating means when the angular deflection of said laser beams reaches a reference position so that contiguous regions of sensitive material are selectively exposed beginning along a common reference line.
A modulation data buffer system for use in a laser pattern generator in which a laser beam is modulated as it sweeps linearly across a target surface, the time for said beam to sweep from one pattern element position to the next adjacent position being t, comprising:
- a source of clock pulses at a rate n/t where n is a small integer,
- a buffer memory means for storing the modulation data for a plurality of consecutive pattern element positions,
- buffer address counter means for addressing and reading out from said memory means the modulation data for said consecutive positions at a rate t for delivery to said modulator, said counter means being incremented by increment pulses applied thereto, and
- data initiation means for beginning the supply of said increment pulses to said counter means when said laser beam passes a reference location on said target surface, increment pulses thereafter being supplied to said counter means at each nth clock pulse occurrence from said source.
A method for controlling the delivery of modulation data to a laser pattern generator of the type ln which at least one laser beam is swept over a target surface at a uniform linear sweep rate, comprising:
- providing a data clock signal at an integral multiple n of the rate at which modulation data for consecutive pattern elements must be delivered to each beam modulator,
- initiating the delivery of modulation data to said beam modulator upon occurrence of the next data clock signal which occurs after said at least one laser beam sweeps past a reference position on said target surface, and thereafter;
- timing the flow of modulation data to each beam modulator at each nth data clock signal.
A system for introducing a selectable delay into the path of pattern data being supplied to an optical beam modulator in a laser pattern generator, comprising:
- a shift register having an input to which said pattern data is serially supplied and having a plurality of positions from any of which the shifted data can be outputted, said shift register being shifted in response to clock pulses applied to a clock pulse input thereof,
- phased data clock generator means for providing plural data clock pulse trains, the clock pulses in each of said trains occurring at uniformly spaced time intervals corresponding to the requisite data delivery rate to said optical beam modulator, the pulses in said plural trains being mutually separated with respect to the pulses in the other trains so as to provide a fixed but different relative phase relationship between one pulse train and each of the other pulse trains,
- first selector means for applying a selected one of said clock pulse trains to said shift register clock pulse input, and
- second selector means for delivering the shifted data outputted from a selected one of said shift register positions to said optical beam modulator.
In a laser pattern generator in which one or more coaligned laser beams are used to expose a pattern onto a target surface, said beams being modulated with pattern data to form said pattern, the improvement comprising:
- deflector means for deflecting all of said beams repetitively across said target surface at a constant rate;
- data clock means producing data clock pulses for enabling the supply of pattern data at a uniform data rate for modulation during said beam deflection;
- time counting means, initiated at a fixed time with respect to the beginning of the deflection of said beam in the absence of positional error of said target surface in the direction of beam deflection, for counting a fixed number of data clock pulses and, upon the completion of said counting, for producing a signal to permit said data clock pulses to enable the supply of pattern data for beam modulation;
- and
- correcting means for measuring positional error of said target surface in the direction of beam deflection and for varying, in response to said measured positional error, the number of data clock pulses counted by said time counting means before said time counting means produces a signal to permit said data clock pulses to enable the supply of pattern data for beam modulation, so that said pattern data is exposed on said target surface at a predetermined location regardless of any positional error of the target surface in the direction of beam deflection.
Dependencies are inferred from the claim text.