This talk will explain

• definition of exposure parameter

• setting up an exposure

• details on exposure parameter

RAITH uses• Round beam with Gaussian-shaped profile• moved along line = name vector scan

step sizetime @ point = dwell time

write field

Writing strategyWriting strategy

number of electrons beam current dwell time= Tdwell Ibeam

2dwellbeam

sTI Dose Area

Unit is µAs/cm²

area step size2

= s2

Rule: To clear an area a certain number of electronshave to hit the sample within a certain area= clearing area dose

s

s

Area exposure - DoseArea exposure - Dose

sTI Dose Line dwellbeam

Unit is pAs/cm

Rule: To clear an line a certain number of electronshave to hit the sample within a certain length= clearing line dose

number of electrons beam current dwell time= Tdwell Ibeam

line step size= s

s

Line exposure - DoseLine exposure - Dose

dwellbeam TI DoseDot Unit is pAs

Rule: To clear an line a certain number of electronshave to hit the sample within a certain point= clearing dot dose

number of electrons beam current dwell time= Tdwell Ibeam

Dot exposure - DoseDot exposure - Dose

beam currentdefined by column, i.e. filament, aperture, voltage, ...

dosedefined by process, i.e. resist, developer, temperature, ...

dwell time and step sizeexposure parameters defined by your needs, e.g.accuracy, GDSII, throughput, ...

Exposure parametersExposure parameters

Parameter Area Line Dotbeam current yes yes yesdose yes yes yesdwell time yes yes yesstep size yes yes no

selectable 3 3 2determined 1 1 1under the condition to clear or equivalently fulfillthe dose equation.

Exposure parametersExposure parameters

Central window to set upall exposure parameters calculated

step size anddwel time

Calculator usingclearing dose andbeam current

Software – Exposure moduleSoftware – Exposure module

Window to perform calculation

beam current and dosestart calculation

Software – CalculatorSoftware – Calculator

Pull design intopositionlist withDrag and Drop

Software – ExposureSoftware – Exposure

Right mouse clickthen open properties

Software – PositionlistSoftware – Positionlist

calculatedparametersas inExposuremodule

choose to expand dialog

Software – PositionlistSoftware – Positionlist

to use parametersfrom Exposure moduleplace tick

Software – PositionlistSoftware – Positionlist

to use individual parameters, removeticks and pressCalculator

Software – PositionlistSoftware – Positionlist

dwell time at eachposition can be re-scaled using dosefactor

Software – PositionlistSoftware – Positionlist

opens dialog toset theseparameters

• Loops

• Line mode

• Meander mode

• Settling time

• Flyback time

• Circular mode

Software – Exposure DetailsSoftware – Exposure Details

• Loops

• Exposure raster

• Line/Meander

• Scan direction

• Settling time

• Flyback time

• Circular mode

Software – Exposure DetailsSoftware – Exposure Details

Each write field isrepeated n times.

(0 means infinitenumber of loops)

Exposure Details - LoopsExposure Details - Loops

Fixed sets basic step size to 2.0 nm

Free allows selection of basic step size for betterplacement accuracy

Exposure Details - RasterExposure Details - Raster

Line mode = element isfilled with each line fromthe same direction.

Meander mode = elementis filled with each line fromthe opposite direction.

See talk “Exposure parameters” for hints whichmode to use.

Exposure Details – Area ModeExposure Details – Area Mode

In Automatic mode,the beam is scanned

along the sideof greatest length

In Manual mode, you can select the direction of the that the beam is scanned

Exposure Details – Scan directionExposure Details – Scan direction

Settling time = waitingperiod at beginning ofeach element

Flyback time = waitingperiod between lines.

Please note, in our softwareFlyback time = settling time flyback factor

Exposure Details – Settling/Flyback timeExposure Details – Settling/Flyback time

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 modeExposure Details – Circular mode

Exposure Details – Dynamic compensationExposure Details – Dynamic compensation

Addresses theissue of thenominal and physical positionof the beam duringan exposure with respect to the sample surface