Standard Operation Procedure EP4

z-stage/z-lift alignment focus calibration (objective) align sensor focus scanner Sample handling stage

Getting started

Turn on the electronic control unit and active antivibration controller Turn on the Spectroscopic box if needed (SE box) Double click on “Accurion Server” icon on desktop to open Accurion server Right click in “session explorer” to choose a session or create a new session (a session corresponds to a folder on hard disk)

When you select “new/open session” an explorer window will pop up where you may create a new folder, e.g. “project 1” After creating a new folder, double click on it and select “choose directory”. You will be asked if you want to convert the current directory to a session folder, click “yes”. The new session will be displayed then in Accurion Server. All following images, measurement results etc. will be saved in this session folder

Double click on “EP4 Control” icon, “Accurion image” icon and “EP4 Model” icon on desktop to open all software components Place your sample on the stage and move the sample under the red alignment spot Open the shutter and adjust exposure time clicking on “camera settings” (50.000 is a good value for exposure time, 20 fps) to see any image. You might need to move the z-lift up or down to find the spot.

Z-Stage / lift control

moving the goniometer down is needed low moving the goniometer down is needed spot is not centered (too low) and ROI signal is low use the z-lift control arrows to move the z-lift and get the spot to the center

spot is centered and ROI signal has its highest value Now z is correctly adjusted high center low

Alignment

Click Align button to open the align control The sample surface might be not perfectly planar. So the complete instrument can be tilted over the sample in order to have the sample surface completely planar. Click Align button to open the align control

or press the auto align button (automatic stage) align sensor If alignment spot is not centered manually change tilt angles and z position by clicking green arrows or press the auto align button (automatic stage) Alpha rotation

align sensor When the 3 angle indicator boxes become green, the surface of the sample is at right angle with the align beam The alignment spot is now centered

Focus Calibration

Click on “focus”, move the red line on a focused part and click 1. 3. 2. focus position close move to an area of the sample containing structures (e.g. dust particles or scratches) Use the slider or double click on number to change the objective position Click on “focus”, move the red line on a focused part and click The focus is now calibrated

Single measuerement

In the main controls, select the objective which is inserted Then set the following settings: AOV: 55° AOI: 55° Polarizer: 50° Compensator: 45° Analyzer: 30°

draw a region of interest (ROI) in the live window draw a region of interest (ROI) in the live window. You have a selection of different forms for ROI. Then make sure that “Default measurement” is selected in the measure slider. 1. 1.

2. Select the desired variables for the measurement, specially the “zones” , “P_range” and “A_range”(ranges should be as small as possible). Activating the “auto” button will allow the program to exceed this rage limit to find the best nulling. 2. 3. 3. Enable the desired measurement in the corresponding tab, “Map” for a sample mapping, “Lambda” for a measurement with wavelength variation, “AOI” for a measurement with angle of incidence variation, and “Timer” for repeating the measurement with a defined timing.

4. For most of them you have to chose new ranges values (angle, wavelength…). You can do this by clicking in the corresponding tab.

5. Press “Start”. The software will measure a four zone nulling and display the results in the graph

You may save the Delta and Psi data directly or send them to EP4Model for further modelling.

Modelling

Open EP4Model window. Your result is already transferred from EP4 Control If the appropriate sample definition is available from a former measurement, you may directly start a “fit”. All results will be displayed in the results section. For a new sample follow the procedure in following pages.

To define all materials in your sample right click in section “Materials” Select Materials from database or create new materials. You need to define all materials in your sample in the Materials definition section.

To create a new material you may right click on the created material and rename it. Afterwards you need to add a dispersion term to it. For measurement at one wavelength you may add a fixed n and k (without dependency on wavelength). Please refer to the manual “dispersions” for further information. After creating the new material you may change dispersion variables and see the effect on resulting n and k.

To define the sample right click in section “Samples” and select „create sample“. A new sample will be created with ambient, layerstack and substrate. By right click on each of them you may select a material from the Material definition section.

Click on “SIO2” in the “layerstack” and type the estimated thickness as well as a lower and upper limit for the fit. On the right graph the curves of delta and psi will already appear. By varying the thickness with the slider you may simulate how the curve would change by changing the thickness.

Go to section “Data & Fit”, right click on “fit for:” and select fit parameters like “thickness” from list. Press the green button to enter.

Press “start fit”. The result together with the error and MSE will be displayed. If any parameter for the fit is wrong an error will be displayed. In that case you may need to change iteration limit to 8000 or tolerance to 1E-8.

To save the results select File/Save Model and select a destination To save the results select File/Save Model and select a destination. All Results as well as Material and Sample definitions, data, fit parameters and screenshots will be saved in the selected destination.

Lambda and AOI variation, Timer, Mapping

Besides of a single measurement you may also measure a wavelength spectrum. For this purpose change to the “Lambda” control tab, select first wavelength, last wavelength and increment. click „enable“ to enable measurement at different wavelengths.

Switch back to Measurement tab Switch back to Measurement tab. Lambda tab will appear green to show that it is activated. Select P_range, A_range and auto and press „start“. The results Delta and Psi vs. Wavelength will be displayed in the graph and can be saved or sent to EP4Model. You may save complete measurement methods and select whole methods from the slider. Total measurement time will be displayed during measurement.

You may also measure a Angle of incidence spectrum (AOI) You may also measure a Angle of incidence spectrum (AOI). For this purpose change to the “AOI” control tab, select first AOI, last AOI and increment. Click „enable“ to enable measurement at different AOI. Switch back to Measurement tab. AOI tab will appear green to show that it is activated. The results Delta and Psi vs. AOI will be displayed in the graph.

For kinetics measurement you may activate the Timer For kinetics measurement you may activate the Timer. This option will repeat all defined measurements in a defined time intervals. Click „enable“ to enable Timer function. Switch back to Measurement tab. Timer tab will appear green to show that it is activated. The results Delta and Psi vs. time will be displayed in the graph.

Besides of a measurement on a ROI you may also do mapping to see a 3D profile of the whole field of view. For this purpose you may select “Mapping” tab and press “calculate map”. This will calculate a Delta and PSI map from last measurement (without focus scan). To have an overall focused map you need to activate “scan” to null with scans and repeat the measurement. It is recommended to select “max speed” for the quality to reduce measurement time.