FILMETRICS F20 STANDARD OPERATION PROCEDURE

Transcription

1 Arizona State University NanoFab FILMETRICS F20 STANDARD OPERATION PROCEDURE Rev C

2 Table of Contents Contents Table of Contents Purpose / Scope Reference Documents Equipment / Supplies / Material Safety Set Up Procedures Operation Procedures Process Data Revision History...5 Page 1

3 1. Purpose / Scope The Filmetrics F20 uses spectroscopic reflectometry to measure film thickness. Single layer or multilayer films on substrates can be measured and analyzed. Typically, the F20 will measure thickness values between 150A and 100um. The large spot size is about 1.5 mm in diameter. 2. Reference Documents Information about this technique is available on the vendor s web site, 3. Equipment / Supplies / Material Reference Si wafer Reference SiO2/Si wafer Tweezers to handle wafers 4. Safety No unique safety requirements 5. Set Up Procedures 1. Turn on the light switch is on the front of system. Allow the light to warm-up for 5-10 minutes. 2. Log into the computer using your ASURITE or ASUAD user name and password. 3. Open the software FILMeasure by double clicking on the icon. 4. The graph will show the reflectance versus wavelength; Initial set-up and model building are done with buttons in the right column. 5. Baseline Reference Measurement. a. Put a clean Si sample, face up, above the mark on the sample stage. i. Select [Baseline] right side and a dialog box opens entitled Take Reflectance Reference ii. Step 1: Ensure Reflectance Material box displays [Si], Check box [X] next to Autoscale Integration iii. Step 2: Take Reference Reading, click [OK]; data is displayed on graph. b. The next dialog box is entitled Take Reflectance Dark i. Tilt the Si reference wafer to about 45 degrees, so the beam is reflected away from the fiber optic detector. ii. Click [OK] and the results are displayed on the screen; generally it is nearly a straight line with occasional small peaks. c. Next, place a reference SiO2/Si wafer on the sample stage. d. In the [Structure box ], use the pull-down arrow and review the list of recent film/substrate combinations; select SiO2/Si if available; otherwise select [Edit structure]. e. Select the [Edit Structure] box, The screen displays the optical model: i. Air, ii. Layer 1, [SiO2 ], [Thickness estimate], [ x ] d [ ] n, [ ] k iii. Substrate [ Si ] Page 2

4 f. Enter the thickness estimate (18000A for this test wafer), check the box next to d (to fit for thickness). Select [Measure]. g. The calculated (red) and measured (blue) reflectance versus wavelength plots should have the Peaks and Valleys aligned. If the thickness and GOF values (box in right column) are close to the expected thickness and GOF is high ( ), the system is working properly. Otherwise, contact Nanofab staff. 6. Operation Procedures 1. Put your wafer on the sample stage under the fiber optic beam. 2. Select the [Film Structure ] button and find a recent film/substrate combination in the list that is has the same layers as your sample. If there is no match then [cancel] and go to step Otherwise, Open the [Edit Structure Box] and the model window opens. It will show the substrate, Film 1, and Medium Air. Note the insert layer boxes on the left side and pulldown arrows for each layer ID. 4. First, select the substrate; the pull down arrow opens the data base of substrate material; select the substrate material for your sample. 5. Select [Film 1]; use the down arrow to obtain a list of material categories: a. Air b. Photo Resist (includes common resists AZ3312 and AZ1518) c. Dielectrics d. Semiconductors e. Metals (must be semi-transparent metal films) f. Others (CoSi2, Fe2O3, ITO, NiP, PZT, TiN, TiN-Palik, ZnSe) Within each category there is a list of materials; choose the material for the 1 st layer. 6. Enter the approximate thickness for your Film 1 and check the Fit box [X] next to d. 7. Add films and select materials using the insert arrows and pull-down arrows. Enter the approximate thickness for each layer and check the Fit box next to d if the software will fit for the thickness of this layer. 8. Select the [Measure] button and evaluate the thickness value(s) and MSE parameters. Also check the plots to see if the measured (Blue) and calculated (Red) reflectances match. If the match is not good, re-do the optical model and/or the initial thickness estimate. 9. Position the curser over the curves on the graph and read out the corresponding wavelength and reflectance values in the boxes at the top of the graph. Save the data if desired. 10. Finished? Close the software; Generally, do not save the program unless it s unique to your project. 7. Process Data There are several options to modify the analysis of the reflectance data. 1. The [Edit Structure] menu contains the optical model. In addition, a tab labeled Solver Options has 2 possibilities, a. analyzer data with displayed data ; b. Fixed range From [xxx] nm to [yyy] nm, allowing fitting over limited wavelength ranges; this can be useful for PR films with large k-values at short wavelengths. Try an initial fit at longer wavelengths such as 500nm to 800nm or from 550nm to 800nm. Page 3

5 2. On the right column is a button labeled [Show Statistics]; select this box to open a window containing: a. Mean b. Medium c. Std. Dev. d. Min e. Max f. Range Followed by a table of values with headings, Measure #, Layer 1 d(a), GOF Commands at the bottom are [save], [copy] [clear] or select rows to [delete] If you select [clear], and then take a series of measurements, the statistics for your sample will be displayed in this box. 3. Another button in the right column is labeled [Show Table]; select this box opens a data table with headings of Wavelength and Reflectance. Commands include Select all, Copy selected data, Save data This allows you to save the table of data to your shared drive; text data can be open using Excel. Page 4

6 8. Revision History Effective Date Originator DESCRIPTION OF REVISION Issue 5/5/09 Name Initial Release A 4/21/15 staff Rev B B Wayne Paulson Rev C update & fit new SOP format C D E F G H Page 5