Spectroscopic Ellipsometry SE800

SENTECH Instruments GmbH

Authors:
Date: 2/5/2004 3:24:34 PM
File: SE800_ShortManual.doc
Version:

2003 by Sentech Instruments GmbH. All rights reserved. Address: Sentech Instruments GmbH
Carl-Scheele-Straße 16
D-12489 Berlin
Germany

Email: info@sentech.de
Web site: http://www.sentech.de

1. General Set Up

The SE 800 consists of a control rack and a ellipsometer desktop. The light source (Xe arc lamp) is located in the control rack. Also included are the documentation of the devices, the installation software and other accessoires like spare parts and mounting aids.

Ellipsometer

Main Components: Base, ACT, sender arm (left), receiver arm (right), sample stage

Options: µ-Spot, motorised x-y stage, autofocus option, automatic goniometer, camera option, liquid cell

Control Unit

Main Components: Controller electronics, spectrometer, IPC, monitor, keyboard, mouse

Options: Slot for the x-y stage controller, Separate monitor for sample monitoring, light source for sample monitoring (FOT)

Light Source

Main Components: Xe lamp, housing (delivered separately) The arc lamp must be fixed and adjusted on site → Instruction Manual: Xe lamp

Options: UV-Extension

Documentation and Installation Software

Main Components: Software description, manual of the Xe lamp, installation CD

Options: Documentation of the device options

Accessories

Set of fuses, mounting aids, spare Xe lamp

SENTECH Calibration standards

2. Set Up and Starting

Following steps should be performed when starting the SE 800:Description:

1. Fixing the Xe lamp inside the housing
   1. Remove the dummy from the housing. Insert the Xe lamp instead of the dummy and fix it by screwing the lamp into the upper and lower socket. A suitable Allen key is included in delivery (as accessory). You are requested to categorically follow the security advices
      → Instruction Manual: Xe lamp, especially the bearing of guards to protect face and hands. It is possible to adjust the lamp inside the housing by adjustment elements outside of the housing. The lamp is delivered in a pre-mounted state. Therefore the adjustment elements should not be modified at first.
2. Removing the Transport Protections
   1. Remove the respective transport protections of the x-y stage and the automatic goniometer, if available.
3. Connecting the Electrical Cabling
   1. Guide carefully the ellipsometer cabling through the cabling hole on the rear side of the control unit. The male and female connectors have identical labels. Screw the grounding cable (green/yellow) onto the grounding base plate of the control unit.
4. Connection of the Optical Fibres
   1. Please handle the optical fibres very carefully, as replacing the fibres implicates a complete re- adjustment of the whole device. Avoid twisting, crushing and bending the fibre below a radius of 10 cm. Connect the fibre of the sending arm with the Xe lamp and guide the fibre of the receiver arm through the cabling hole on the rear side of the control unit in order to connect it with the spectrometer. (see fig. 3)
5. Positioning of the Ellipsometer Arms at 70° (recommended)
   1. For starting-up it is recommended to position the ellipsometer arms of the SE 800 at a degree of 70°. If you have options like mapping, µ-spot or automatic goniometer, please take special care when starting up to avoid physical collisions of the moving mechanical parts with each other.

Please follow the following indications when performing later alterations (by the customer):

• Do not move the SE 800 until it is completely disconnected from the power supply. Please switch the SE 800 off before connecting and disconnecting any cables.
• Disconnect first the fibre from the Xe lamp and the spectrometer respectively which is accessible from the rear of the control unit. Disconnect the electrical connections between the control unit and the ellipsometer subsequently. Eventual devices must be also electrically disconnected from the control unit. Guide the cables carefully through the cabling hole on the rear side of the control unit.
• Remove the Xe lamp from the housing. Please follow the security measures, like bearing of guards to protect face and hands → Instruction Manual: Xe lamp. A dummy must be inserted.
  ATTENTION:The Xe lamp must always be carefully packed and shock mount transported.
• If you have options like mapping or automatic goniometer, please mount the appropriate transport protections. If you have µ-spots it is recommended to remove the front lenses (spot lenses). There is normally no re-adjustment of the µ-spots required.
• Avoid any kind of vibrations. Especially the ACT and its mounting, the µ- spots and their mechanical parts are very sensitive.

3. SE 800-Single Measurement

3.1. Starting and Initialization of the Components

The SE 800 can be switched on together with all components by a on/off switch (Main Power). The computer and the Xe lamp can be switched on and off separately, like other additional devices. After switching the main switcher on, the electronic control unit of the SE 800 is on and the operating system starts loading. The software of the ellipsometer (SpectraRay) can be now started by pressing the corresponding button on the desktop. The SE 800 is ready for operation if the Xe lamp and the additional devices are on. Stable measurements can be performed after an operating time of 5-10 min of the Xe lamp.

Set the position of the arms first at 70° for ellipsometers with manual goniometer and motorised stage in order to avoid collisions between stage and arms during the initialisation of the stage. For motorised goniometer the arms are automatically positioned at 70° after the initialisation of the goniometer.

3.2. Measurements

3.2.1. Sample Alignment

Place the sample you want to measure onto the tilt stage and adjust the correct height and tilt of the stage by adjusting the light beam of the Auto Collimating Telescope (ACT) to the beam of the ellipsometer.

Height adjustment: Adjust the sample in the right position of the ellipsometer beam using the height adjustment of the stage. Please check the height of the sample in the position “sample height“ of the ACT. The reticle of the ACT must be thereby clear and sharp.

Tilt adjustment: Adjust the sample perpendicularly to the ellipsometer plane using the tilt screws of the stage. In the position “tilt” of the ACT the displacement of the reticle relative to the zero point of the scale can be observed.

3.2.2. Ellipsometric Measurement

By pushing the measurement button in the task bar of the SpectraRay surface you can open the window to set up and perform an ellipsometric measurement.

In this window you can select the angles, the wavelength range, the values to be measured and the measurement mode. By pressing the “Measure” button you can start a measurement.

After leaving the measurement windows by pressing the “Quit” buttons the result of the measurement will be stored in the data area “Data” of the SpectraRay surface. The measured data can be accessed as graph or as table by double clicking the entry in the data area.

3.3. Analysis

The analysis of the measurements of the SE 800 is done by comparison of the real measurement results with the results of a model. Thereby selected parameters are varied until the best match is reached between the results of the measurement and those of the model. The layer model is generated by shifting the material data from the material library “Materials” into the model area “Model”. The buttons are denoted as following:

F7 -Load: Loads the marked material from the material library “Materials” into the “Model” window

Save: Saves the marked material in the “Model” window

Replace: Exchanges the marked material in the “Model” window with the material marked in the material library

Remove: Deletes the material marked in the “Model” window

You can open a table (spreadsheet) by clicking the symbol “Fit Parameter“ which contains a summary of all model parameters. In this table you can select the parameters to be fitted and their start values.

You can open the Fit Window by clicking the symbol “Fit”. By pressing the “Fit” button you can start a fit after which the result will be displayed tabulated. You can display the results graphically and print them subsequently using the “Plot” button.

You can save and access at any the generated experiments, models, materials and spectroscopic measurements separately and as experiments respectively time using the menu “File”. Following file extensions are used:
Experiments: *.exp
Models: *.mod
Spectra (measured values): *.spc
Materials: *.mat
ASCII: *.dat

You can access the results of mapping measurements and measurements done using prepared scripts from the SpectraRay surface. A more detailed description of the software can be found in the software manuals (→ SpectraRay-Manual → Manual: Mapping).

4. Working with Application Programs

Applications are macro programs allowing automatic measurement cycles. By pressing the “Measure“ button, automatic proceeding for data collection, loading of the correct model of the sample and fitting of the measured results will start, and the results will be subsequently displayed on the screen.
The applications can be saved in any desired folder. For later access via the “Application runner“ you must set the path in the path directory correspondingly using the “Directory“ symbol.

4.1. Accessing and Starting of Applications

You can access the different applications using the button “Application runner“. By pressing that button you open the application library (fig 12) which contains all applications listed and sorted according to their use (definition).
You can select a particular application by marking it with the mouse. Thereupon the name of the application will be marked blue. To demonstrate this, the application “SiN on Glass (50-70 nm)“ is used in the following as an example. You can start the application by pushing the “Run” button.
The application window (fig 13) contains the name of the application, the “Measure” button which starts the measurement, a yellow window containing the results of the performed measurement and the “Quit” button to terminate the application. Pressing the “Quit” button closes the current application window and the application library (fig 12) is displayed from which you can select another application. Pressing the “Quit” button on the application window closes the application library and the start window of SpectraRay becomes accessible again.

4.2. Application Library

4.3. Application Window

Besides the standard applications you can find in addition programs allowing the measurement of statistical values. The determination of the accuracy of an ellipsometric analysis is done by performing automatically several successive measurements and the subsequent determination of the mean value and the standard deviation of the measurements.

Enter the number of subsequent measurements into the description field “Number”. Note that this number must be higher than 3. You can start the measurement by pressing the “Measure” button. After the measurement is finished the mean value and the standard deviation will be displayed in the yellow field of the application window. The parameter Q indicates the quality of the fit of each single measurement.

Pressing the button “Statistics d” or “Statistics n” displays graphically the single measurement results of the layer thickness and refractive index respectively (figs 16 and 17).
By pressing the “Reset” button you can start a new accuracy analysis. You can terminate the application by pressing the “Quit” button.