A transparent film on Si wafer

Contents

1 Si_jaw.mat

2 Cauchy.mat

3 Adjust the thickness manually

4 Normal Fit

1. Si_jaw.mat

1. Click on the "Model" window, and you see the menu change.

2. Click the "AddLayer" from the menu or the drop-down menu popped up by right-clicking on the window.

3. Choose "Si_jaw.mat" from the file directory, as the Si substrate.

• Note: Other materials are also available in the file directory.

4. The "Layer" dialog box appears. Click "OK".

• Thickness should be set to be 1 mm because the substrate thickness is too thick.

5. The Si substrate is shown in the "Model" window.

2. Cauchy.mat

1. Click the "AddLayer" again from the menu or the drop-down menu popped up by right-clicking on the window.

2. Open cauchy.mat, which is a model for transparent or semi-transparent film.

3. Cauchy Layer window appears.

• Note: The cauchy layer model is a function of optical constants (see Cauchy Layer).

4. Make sure that k amplitude is zero, because no absorption is assumed.

5. Check fit boxes of "Thickness", "An", and "Bn", and click "OK".

• "Cn" does not affect the result normally, but you can check it if necessary.

3. Adjust the thickness manually

1. Adjust the thickness to fit the model curve with the experimental data, using a mouse.

• As can be seen in the Graph window in the following figure, the experimental data shows an interference pattern.
• Move the cursor on the cauchy model in the Model window, and rotate the scroll wheel on the mouse, to change the thickness.
  • When holding the shift key and rotating the scroll wheel, you can make a coarse change of thickness.
  • The calculated data is shown in the "Generated Data" window, when you rotate the scroll wheel on the mouse.
• You can also change the thickness in the Cauchy model window.
• If the calculated data is not shown in the Generated Data window, right-click on the "Generated Data" window to popup the drop-down menu, and choose "Generate Data".

4. Normal Fit

1. Right-click on the "Fit" window to pop-up the menu.

2. Click the "Normal Fit" for Thickness and An.

3. As can be seen in the "Fit" window, the thickness is 698.715 nm, and MSE (Mean Squared Error) is 454.8. The number of MSE should be less than 10 for the best fitting.

• Note: The best MSE should be around 1.

4. Open the Cauchy model window by clicking the cauchy model in the Model window.

5. Check fit box of "Bn", and click "OK".

6. Right-click on the Fit window to pop-up the menu.

7. Click the "Normal Fit" for Thickness, An, and Bn.

8. The fitting thickness is 749.865 nm, and MSE is 7.293.

9. Open the Cauchy model window by clicking the cauchy model in the Model window.

10. Check fit box of "Cn", and click "OK".

11. Right-click on the Fit window to pop-up the menu.

12. Click the "Normal Fit" for Thickness, An, Bn, and Cn.

13. The fitting thickness is 750.003 nm, and MSE is 7.261.

14. If you want to have the better result, try to add a layer of "srough.mat", which is surface roughness correction.