Methods and systems for precisely relatively positioning a waist of a pulsed laser beam and method for controlling energy delivered to a target structure

Abstract

A method and system for locally processing a predetermined microstructure formed on a substrate without causing undesirable changes in electrical or physical characteristics of the substrate or other structures formed on the substrate are provided. The method includes providing information based on a model of laser pulse interactions with the predetermined microstructure, the substrate and the other structures. At least one characteristic of at least one pulse is determined based on the information. A pulsed laser beam is generated including the at least one pulse. The method further includes irradiating the at least one pulse having the at least one determined characteristic into a spot on the predetermined microstructure. The at least one determined characteristic and other characteristics of the at least one pulse are sufficient to locally process the predetermined microstructure without causing the undesirable changes.

1 . A method for precisely relatively positioning a waist of at least one pulsed laser beam to compensate for microscopic positional variations of one or more predetermined target structures to be laser processed, the method comprising: 
 measuring a position of at least one alignment target formed at a predetermined measurement location to obtain at least one measurement;    predicting a relative location of one or more predetermined target structures and the at least one laser beam based at least in part on the at least one measurement to obtain one or more predicted relative locations;    generating at least one laser beam including at least one pulse;    inducing relative motion between the one or more predetermined target structures and the at least one laser beam based on the predicted relative location;    updating the predicted relative location during relative motion based at least in part on updated position information, the updated position information being obtained during the relative motion; and    irradiating the at least one pulse onto a spot on the one or more predetermined target structures to process the one or more predetermined target structures based at least in part on the updated position information.    
     
     
         2 . The method of  claim 1 , comprising processing multiple target structures with multiple laser beams.  
     
     
         3 . The method of  claim 2 , comprising: 
 updating the predicted relative location of multiple laser beams and multiple target structures during relative motion based at least in part on updated position information, the updated position information being obtained during the relative motion; and    irradiating the at least one pulse onto multiple spots on the multiple target structures to process multiple target structures based at least in part on the updated position information.    
     
     
         4 . The method of  claim 1 , comprising obtaining three-dimensional information at a plurality of predetermined locations about the target material, the locations being a combination of at least one predetermined location at which an alignment target is formed and at least one other predetermined location at which an alignment target is not formed and which is suitable for an optical measurement; predicting the location of the target material relative to a laser beam waist position based on the three-dimensional information including three-dimensional information obtained at the at least one other predetermined location to obtain a three-dimensional location prediction; inducing motion of the target material relative to a laser beam waist position based on the prediction; generating a laser beam including at least one pulse; and irradiating the at least one pulse into a spot on the target material to process the target material.  
     
     
         5 . A system for precisely relatively positioning a waist of at least one pulsed laser beam to compensate for microscopic positional variations of one or more predetermined targets to be laser processed, the method comprising: 
 means for measuring a position of at least one alignment target formed at a predetermined measurement location to obtain at least one measurement;    means for predicting a relative location of one or more predetermined targets and the at least one laser beam based at least in part on the at least one measurement to obtain one or more predicted relative locations;    means for generating at least one laser beam including at least one pulse;    means for inducing relative motion between the one or more predetermined targets and the at least one laser beam based on the predicted relative location;    means for updating the predicted relative location during relative motion based at least in part on updated position information, the updated position information being obtained during the relative motion; and    means for irradiating the at least one pulse onto a spot on the one or more predetermined targets to process the one or more predetermined targets based at least in part on the updated position information.    
     
     
         6 . The system of  claim 5 , wherein the means for updating comprises a position encoder.  
     
     
         7 . The system of  claim 5 , wherein the means for updating comprises an optical sensor.  
     
     
         8 . A method for laser processing a multi-material device including a substrate and at least one microstructure designated for removal within a 1D or 2D array of microstructures, the microstructures of the array being disposed at a pre-determined spacing, the positioning subsystem inducing relative motion between the device and laser beam waists, the processing to remove at least one microstructure designated for removal within the array without causing undesirable damage to the substrate, adjacent microstructures, or any layer disposed between a microstructure and the substrate, the method comprising: 
 obtaining information to identify microstructures designated for removal within a row or column of the array of microstructures, and to identify alignment targets about the microstructures, each target having a predetermined location relative to the microstructures;    scanning at least one measurement beam relative to an alignment target to obtain at least one signal representative of the alignment target location, and processing the at least one signal to determine a target location estimate;    predicting a location of at least one designated microstructure based on the estimate;    planning and generating a trajectory to position one or more pulsed laser beams relative to one or more designated microstructures so that the microstructures and pulsed laser beam waists substantially coincide at a location along a laser beam centerline;    generating a single laser pulse;    forming at least two spatially separated pulses from the first pulse wherein the step of forming includes spatially splitting the single pulse to selectively direct the separated pulses along multiple directions, and wherein the step of forming includes utilizing pre-determined spacing information, and at least one of an alignment target estimate and a predicted location to adjust the separation between the spatially split pulses so as to cause a waist of each spatially split pulse to coincide with a designated microstructure;    irradiating at least one microstructure with the spatially separated pulses wherein a beam waist of each spatially separated pulse and a microstructure substantially coincide;    wherein the processing of the at least one microstructure with the at least two spatially separated pulses during relative motion of the at least one microstructure and the beam waists precisely positioned relative to the at least one microstructure, whereby throughput of the processing system is substantially improved.    
     
     
         9 . The method of  claim 8 , wherein the processing occurs in a single pass operation controlled with a positioning subsystem of a laser processing system.  
     
     
         10 . The method of  claim 8 , wherein said trajectory defines trajectories of a plurality of pulsed laser beams.  
     
     
         11 . The method of  claim 8 , wherein the trajectory is based on three dimensional information.  
     
     
         12 . The method of  claim 8  wherein the step of planning and generating comprises: producing a first motion profile corresponding to a first trajectory segment, the profile representative of approximately constant velocity of relative motion of the at least one microstructure and corresponding waist locations generally along a row or column of the 1D or 2D array, the motion occurring during a first specified time interval, or over a first specified distance, at which one or more microstructures are to be processed with the at least one laser pulse, and producing a second motion profile corresponding to a second trajectory segment, the second motion profile representative of an acceleration or deceleration during a second specified time interval, or over a second specified distance, at which the microstructures and corresponding waists are accelerated to achieve a predetermined velocity for processing with at least one laser pulse; and moving the microstructures relative to a laser beam axis in accordance with the trajectory plan.  
     
     
         13 . The method of  claim 8  wherein the step of splitting simultaneously produces the separated pulses.  
     
     
         14 . The method of  claim 8  wherein exactly two spatially separated pulses are formed, and wherein the two pulses irradiate one or two microstructures, or none, with the two spatially separated pulses.  
     
     
         15 . A method for use in processing structures on or within a semiconductor substrate using N series of laser pulses to obtain a throughput benefit, wherein N≧2, the structures being arranged in a plurality of substantially parallel rows extending in a generally lengthwise direction, the N series of laser pulses propagating along N respective beam axes, the method comprising planning at least one trajectory for simultaneously moving in the lengthwise direction the N laser beam axes substantially in unison relative to the semiconductor substrate so as to process structures on or within the semiconductor substrate with the respective N series of laser pulses, whereby the trajectory is such that the throughput benefit is achieved while ensuring that the trajectory represents feasible velocities for each of the N series of laser pulses and for each of the respective structures processed with the N series of laser pulses.  
     
     
         16 . The method of  claim 12 , wherein said trajectory comprises one or more acceleration and velocity profiles.  
     
     
         17 . A method for use in processing structures on or within a semiconductor substrate using N series of laser pulses to obtain a throughput benefit, wherein N≧2, the structures being arranged in a plurality of substantially parallel rows extending in a generally lengthwise direction, the N series of laser pulses propagating along N respective beam axes until incident upon selected structures in N respective distinct rows, the method comprising: determining a joint velocity profile for simultaneously moving in the lengthwise direction the N laser beam axes substantially in unison relative to the semiconductor substrate so as to process structures in the N rows with the respective N series of laser pulses, whereby the joint velocity profile is such that the throughput benefit is achieved while ensuring that the joint velocity profile represents feasible velocities for each of the N series of laser pulses and for each of the respective N rows of structures processed with the N series of laser pulses.  
     
     
         18 . The method of  claim 17 , wherein the determining step comprises: determining for each of the N rows a velocity profile for moving in the lengthwise direction the respective laser beam axis relative to the semiconductor substrate so as to process structures with the respective series of laser pulses, thereby resulting in N individual velocity profiles.  
     
     
         19 . The method of  claim 18 , wherein the joint velocity profile does not exceed the minimum value of the N individual velocity profiles while a structure is processed with a laser pulse.  
     
     
         20 . The method of  claim 17 , wherein the joint velocity profile includes one or more sections of constant velocity.  
     
     
         21 . The method of  claim 17 , wherein N=2.  
     
     
         22 . The method of  claim 17 , wherein the first and second series of laser pulses have respective first and second sets of optical properties, and wherein the first and second sets are different from one another.  
     
     
         23 . The method of  claim 17 , wherein the first laser beam axis is offset from the second laser beam axis by some amount in a direction parallel to the lengthwise direction of the rows.  
     
     
         24 . The method of  claim 17 , further comprising: generating the N series of laser pulses; and moving in the lengthwise direction the N laser beam axes in unison relative to the semiconductor substrate, in accordance with the joint velocity profile, so as to selectively irradiate structures in the N rows with the respective N series of laser pulses.  
     
     
         25 . The method of  claim 24 , wherein the generating step comprises: generating the N laser beams from N respective lasers.  
     
     
         26 . The method of  claim 24 , wherein the generating step comprises: generating a single laser beam from a single laser; and splitting the single laser beam to form the N laser beams.  
     
     
         27 . The method of  claim 24 , wherein the generating step is commenced based upon a trigger signal.  
     
     
         28 . The method of  claim 27 , wherein the trigger signal is generated based upon a timing signal.  
     
     
         29 . The method of  claim 27 , wherein the trigger signal is generated based upon a comparison of one or more desired target locations and one or more locations at which the laser beam axes intersect the semiconductor substrate.  
     
     
         30 . The method of  claim 24 , further comprising: during the moving step, dynamically adjusting the relative spacing among two or more of the N laser beam axes.  
     
     
         31 . The method of  claim 30 , wherein: the adjustment of the relative spacing is in a direction substantially perpendicular to the lengthwise direction of the rows.  
     
     
         32 . The method of  claim 24 , wherein the moving step comprises: moving the N laser beam axes.  
     
     
         33 . The method of  claim 24 , wherein the moving step comprises: moving the semiconductor substrate.  
     
     
         34 . The method of  claim 24 , further comprising: selectively blocking one or more of the N laser beams from reaching the semiconductor substrate.  
     
     
         35 . The method of  claim 24 , wherein the N laser beams reach the workpiece at a substantially simultaneous time.  
     
     
         36 . The method of  claim 17 , wherein the determining step comprises: generating a set of master coordinates; determining for each structure in the N rows to be laser irradiated a relative offset coordinate from a master coordinate; and determining a joint velocity profile for the N rows based on the set of master coordinates.  
     
     
         37 . The method of  claim 17 , wherein the structures comprise electrically conductive links and the irradiation of a link results in severing that link.  
     
     
         38 . The method of  claim 21 , wherein the first laser beam axis is offset from the second laser beam axis by some amount in a direction parallel to the lengthwise direction of the rows.  
     
     
         39 . A link processing system comprising: 
 one or more lasers producing a first laser beam;    a splitter receiving said first laser beam as an input and generating a separated plurality of laser beams;    an orientation controller receiving said separated plurality of laser beams and controlling a relative orientation of said separated plurality of laser beams;    optics configured to focus said separated and oriented plurality of laser outputs onto a corresponding plurality of links of an array of links; and    a trajectory planner configured to produce one or more acceleration and/or velocity profiles for positioning beam waists of said separated and oriented plurality of laser outputs at link locations coincident with pulses of said separated plurality of laser beams.    
     
     
         40 . A method of laser processing one or more links on an electronic device, said method comprising: 
 forming N spatially separated laser beams along N different beam paths, wherein N≧2;    planning one or more trajectories of said N spatially separated laser beams along a scan beam path;    forming one or more beam spots on said electronic device with said N spatially separated laser beams;    moving said one or more beam spots relative to said electronic device in accordance with said one or more trajectories; wherein multiple spatially separated laser beam spots process locations on said electronic device during a pass of said beam spots over said electronic device.    
     
     
         41 . A system for laser processing a multi-material device including a substrate and at least one microstructure designated for removal within a 1D or 2D array of microstructures, the microstructures of the array being disposed at a pre-determined spacing, the positioning subsystem inducing relative motion between the device and laser beam waists, the processing to remove at least one microstructure designated for removal within the array without causing undesirable damage to the substrate, adjacent microstructures, or any layer disposed between a microstructure and the substrate, the system comprising: 
 means for obtaining information to identify microstructures designated for removal within a row or column of the array of microstructures, and to identify alignment targets about the microstructures, each target having a predetermined location relative to the microstructures;    means for scanning at least one measurement beam relative to an alignment target to obtain at least one signal representative of the alignment target location, and processing the at least one signal to determine a target location estimate;    means for predicting a location of at least one designated microstructure based on the estimate;    means for planning and generating a trajectory to position one or more pulsed laser beams relative to one or more designated microstructures so that the microstructures and pulsed laser beam waists substantially coincide at a location along a laser beam centerline;    means for generating a single laser pulse;    means for forming at least two spatially separated pulses from the first pulse wherein the step of forming includes spatially splitting the single pulse to selectively direct the separated pulses along multiple directions, and wherein the step of forming includes utilizing pre-determined spacing information, and at least one of an alignment target estimate and a predicted location to adjust the separation between the spatially split pulses so as to cause a waist of each spatially split pulse to coincide with a designated microstructure;    means for irradiating at least one microstructure with the spatially separated pulses wherein a beam waist of each spatially separated pulse and a microstructure substantially coincide;    wherein the processing of the at least one microstructure with the at least two spatially separated pulses during relative motion of the at least one microstructure and the beam waists precisely positioned relative to the at least one microstructure, whereby throughput of the processing system is substantially improved.