The Filmetrics F20 Thin Film Measurement System measures thickness and optical constants quickly. Analysis of the reflectance from the top and bottom of the film to be measured shows the thickness, the extinction coefficient and the index of refraction in about a second. Any smooth, transparent or thin film with minimal light absorption can be measured.
For example: SiO2, Photoresists, Polyimides, DLC, Polymer layers, SiNx, Polysilicon, Silicon, Amorphous Silicon.
For thickness measurements, most cases require just a smooth, reflective substrate. For optical constant measurements, a flat specularly reflecting substrate is required. If the substrate is transparent, the substrate back must be prepared so that it is not reflective.
Examples: Silicon Glass Aluminum GaAs Steel Polycarbonate Polymer films
The Filmetrics F20 System will measure according to the following table.
|Thickness only||150Å to 50μm|
|Thickness with n and k||1000Å to 5μm|
|Wavelength Range||400 to 1000nm|
|Accuracy||Greater of 10Å or .4%|
1. Turn on the light by flipping the green switch on the left of the filmetrics box. Wait a few minutes for the lamp to warm up.
2. On the computer desktop double click on the FILMmeasure icon.
3. Select the structure to be measured from the drop down menu on the right of the screen.
4. Click on 'edit structure' below the drop down menu. Under the menus 'layer' and 'material' make sure the correct material for substrate, 1, and medium are selected.
5. Enter in a rough estimate for the thickness (in nanometers) of the film and click 'OK'.
6. Click on 'baseline' and select the reference material which is usually Si.
7. Put the Si reference wafer on the stage. It is under the computer desk in the top left box in a bag.
8. Click 'OK' and then remove the reference wafer and click 'OK'.
9. There is a Sio2 on Si reference wafer in the bag as well. If you want to check the accuracy of the equipment place the wafer under the light source and make sure the light is hitting the dot on the wafer. Click measure to get the thickness. Compare it with the measurement stated on the case.
10. Place the sample to be measured on the stage and click measure. The goodness of fit should be pretty close to one for it to be an accurate measurement. The thickness, goodness of fit, n, k and roughness are given on the left in a white box.