A partially absorbing film on Si wafer

Contents 

1 Point-by-Point Fitting

1.1 Si_jaw and cauchy.mat

1.2 Change the spectral range to the transparent region

1.3 Fitting the raw data in the transparent region with calculation

1.4 Change the spectral range back to the whole region

1.5 Fitting

2 Global Fitting

1. Point-by-Point Fitting

• This is a fitting method appropriate for the sample showing an partial absorption in the wavelength range measured.
• The substrate is assumed to be a Si wafer.
• Assume that an organic film on Si wafer was measured, and saved as organic_si.dat.
• Assume that organic_si.dat is loaded in the Experimental window.

1.1 Si_jaw and cauchy.mat

1. Repeat the Si_jaw and cauchy.mat processes in the previous section of the transparent film on Si.

2. As can be seen in the Graph window, the interference peak heights are not the same, suggesting the optical absorption.

1.2 Change the spectral range to the transparent region

1. Right-click on the "Experimental Data" window to popup the menu.

2. Choose the "Range Select".

3. The "Select Experimental Data Range" window appears.

4. Change the wavelength range to the transparent region, and click "OK".

• In this example, the start wavelength of 600 nm is input.

5. The spectral range of the graph is changed.

1.3 Fitting the raw data in the transparent region with calculation

1. Repeat the "Adjust the thickness manually" and "Normal Fit" processes in the previous section of the transparent film on Si.

1.4 Change the spectral range back to the whole region

1. Right-click on the "Experimental Data" window to popup the menu.

2. Choose the "Range Select".

3. The "Select Experimental Data Range" window appears.

4. Change the wavelength range to the original region, and click "OK".

• In this example, the start wavelength of 240 nm is input.

5. The spectral range of the graph is changed.

1.5 Fitting

1. Click on the "Fit" window to popup the menu.

2. Choose "Edit Parms".

3. The "Edit Fit Parameters" window appears.

4. Click "Delete All Parms" to check off Thickness, An, Bn, and Cn in the Cauchy model window.

• You can also check off them in the Cauchy model window manually.

5. Click "OK".

6. Open the Cauchy model window.

7. Check n and k in the "Opt Const Fit" box.

8. Click "OK".

9. Right-click on the "Fit" window to popup the menu.

10. Choose "Pt by Pt".

11. The following dialog box appears.

12. Click "OK".

13. The fitting result is shown in the "Fit" window.

• If you want to know the optical constants at a particular wavelength, go to the Cauchy model window, and click the "Optical Constants >>" button in the Cauchy model window.