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Published byFelix Long Modified over 9 years ago
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This talk will explain definition of exposure parameter setting up an exposure details on exposure parameter
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RAITH uses Round beam with Gaussian-shaped profile moved along line = name vector scan Writing strategy
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number of electrons beam current dwell time = T dwell I beam Unit is µAs/cm² area step size 2 = s 2 Rule: To clear an area a certain number of electrons have to hit the sample within a certain area = clearing area dose s s Area exposure - Dose
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Unit is pAs/cm Rule: To clear an line a certain number of electrons have to hit the sample within a certain length = clearing line dose number of electrons beam current dwell time = T dwell I beam line step size = s s Line exposure - Dose
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Unit is pAs Rule: To clear an line a certain number of electrons have to hit the sample within a certain point = clearing dot dose number of electrons beam current dwell time = T dwell I beam Dot exposure - Dose
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beam current defined by column, i.e. filament, aperture, voltage,... dose defined by process, i.e. resist, developer, temperature,... dwell time and step size exposure parameters defined by your needs, e.g. accuracy, GDSII, throughput,... Exposure parameters
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Parameter AreaLineDot beam currentyesyesyes doseyesyesyes dwell timeyesyesyes step sizeyesyesno selectable332 determined111 under the condition to clear or equivalently fulfill the dose equation. Exposure parameters
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Central window to set up all exposure parameters calculated step size and dwel time Calculator using clearing dose and beam current Software – Exposure module
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Window to perform calculation beam current and dose start calculation Software – Calculator
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Pull design into positionlist with Drag and Drop Software – Exposure
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Right mouse click then open properties Software – Positionlist
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calculated parameters as in Exposure module choose to expand dialog Software – Positionlist
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to use parameters from Exposure module place tick Software – Positionlist
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to use individual parameters, remove ticks and press Calculator Software – Positionlist
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dwell time at each position can be re- scaled using dose factor Software – Positionlist
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opens dialog to set these parameters Loops Line mode Meander mode Settling time Flyback time Circular mode Software – Exposure Details
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Loops Exposure raster Line/Meander Scan direction Settling time Flyback time Circular mode Software – Exposure Details
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Each write field is repeated n times. (0 means infinite number of loops) Exposure Details - Loops
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Fixed sets basic step size to 2.0 nm Free allows selection of basic step size for better placement accuracy Exposure Details - Raster
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Line mode = element is filled with each line from the same direction. Meander mode = element is filled with each line from the opposite direction. See talk “Exposure parameters” for hints which mode to use. Exposure Details – Area Mode
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In Automatic mode, the beam is scanned along the side of greatest length In Manual mode, you can select the direction of the that the beam is scanned Exposure Details – Scan direction
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Settling time = waiting period at beginning of each element Flyback time = waiting period between lines. Please note, in our software Flyback time = settling time flyback factor Exposure Details – Settling/Flyback time
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Circular mode = round elements are decomposed into dots dots are exposed in centric rings vertices are not used Exposure parameters = Uses area parameters Exposure Details – Circular mode
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Exposure Details – Dynamic compensation Addresses the issue of the nominal and physical position of the beam during an exposure with respect to the sample surface
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