What’s in Tutorial 1.Brief overview of GUI 2. Calculating filmstack parameters 3. Data simulation and sensitivity analysis 4.Error estimation analysis 5.New options in ver. 3.0rc 6.New feature build 12/21/2004
TFCompanion is a multi-threaded application – this means that there maybe several windows open and accessible at the same time. To toggle between different windows – use OS specific keyboard short-cuts: For MS Windows and Linux (KDE 2)—ALT+Tab For Linux (Gnome) –CTRL+ALT+[Fn] (F1-F8) For MAC OS X – check “man screen” for details Other OS – use OS specific keyboard shortcuts
Brief GUI overview Functionality and information is concentrated in the main screen Other data and functionality is accessed using main menu or Toolbar buttons GUI configuration and options depends on user profile Next slide shows main screen (user:Administrator)
Calculation Calculation include 4 steps: 1.Load measured data (from DB or file) 2.Create & Load filmstack model (please review Filmstack tutorial for details) 3.Select calculated parameters 4.Calculate and review the results
Calculation-Loading data TFCompanion supports data import from file in most popular formats: Beaglehole Instruments Sopra Woollam JY Rudolph Technologies Format is recognized automatically.
Calculation- selecting parameters We have loaded filmstack model – now need to select calculated parameters We are using 150A SiON/Si filmstack SiON dispersion is represented using Tauc- Lorentz approximation
Calculation- selecting parameters We are interested in Thickness and n,k @248 nm Directly calculated parameters are Tauc- Lorentz approximation coefficients – not n,k n,k @ 248nm – they will be displayed parameters we will be prompted to select TL coefficient to calculate (but not display)
Calculation We have selected parameters and are ready for calculation. We have two options: –Selecting Calculate button starts calculation directly –Selecting Calculate from toolbar or menu starts Calculation dialog and gives more control We select Calculate button.
Calculation We will now try another option – select calculation from the ToolBar We will do the same calculation but in the Calculation dialog and will “cache” (save the results) Please review Calculation tutorial for more details
Calculation-Review results We have cached results (saved to memory). Note that the cache can be saved as a part of the “project” and loaded during next session Now we will close Calculation dialog and start Compare Data center from the main menu.
Calculation- review results We can now print or save plot to a file (using menu options in the plot dialog) Please review Compare data tutorial for more details After closing this dialog we return to the main menu Now we will review the SiON layer detail
Data simulation-sensitivity We will now look at the example of sensitivity calculations. We will use the same filmstack 2um SiO2/Si We are interested in sensitivity of R (unpolarized reflectance) measurement to tilt (angle of incidence) at 70 deg. Sensitivity is dR/dA (A - angle) we will use %/deg
TFCompanion incorporates a powerful engine to estimate measurement precision. The idea is to propagate the precision of instrument measured parameters (e.g. reflectance, Delta, Psi etc.) to precision of Filmstack parameters
Error estimation Basic error estimation is available in advance version. Full capability is available in enterprise version We will discuss here only basic example
Error Estimation We will use 150 A SiON/Si filmstack and assume standard SE measurement (we will a template that describes typical SE) We will calculate the same parameters as in the calculation example (in this tutorial) We will be interested in measurement precision of parameters as a function of layer Thickness
TFC ver. 3.0rc – new options Several improvements are introduced: 1.Simulate fit option 2.Direct n,k calculation option 3.Direct measured vs. calculated review (w/o caching)
Simulate fit option Evaluate filmstack and compare results of simulation with the measured data Simulation is done directly from the main screen Simulated spectra match the structure (range and type) of the measured spectra
Simulate fit option Steps to perform: 1.Load measured data 2.Load or create model filmstack 3.Use Simulate Fit button 4.Review the results
Direct n,k calculation In most cases n,k dispersion spectra is represented by known Tabular materials or using Parameterized approximations (Tauc- Lorentz, Cauchy, etc.) However, sometimes direct n,k calculation is the only option (e.g. pseudo-dielectic function of substrate, unknown materials like organic ARC).
Direct n,k calculation(cont.) The ability of direct n,k calculation depend on amount of measured data at each wavelength The number of calculated parameters should be less or equal to number of measured values (Delta, Psi at each wavelength allows calculate n,k at each wavelength)
Direct n,k calculation steps 1.Load measured data 2.Load or create model filmstack 3.Select calculated filmstack parameters 4.Calculate 5.Review the results
Direct n,k calculation (cont) We selected all n,k parameters and thickness Because we have SE measurement at one angle – we have too many calculated parameters now. We will remove calculate flag at one of k parameters in the Vis range (next slide)
Normally calculation is very fast (<1s) but we have now ~880 calculated parameters so it will take few minutes Calculation progress dialog pops up if calculation is longer than 2 sec. User can stop the calculation at any time (latest results will be displayed)
Direct n,k calculation (review) Results of the calculation are displayed directly in the main screen (we use “full screen” option to review the fit) The fit is quite good, as expected (except for couple of points, one is where we did not calculate the k value)
Direct n,k calculation review We can see all the calculation results on the main screen but now we can click on the layer and display n,k dispersion plot (and table of values) The plot is somewhat choppy, as expected, because we calculated each point practically independent (no smoothing effect of parameterized material model)
Now we have a good approximation of n,k dispersion. There are several options: –Save this as a new material (Use as is); –Use parameterized model (e.g.Tauc-Lorentz) and fit it to current n,k dispersion (see Materials tutorials ) –Export the data and modify it
New features (build 12212004) Backside reflection correction (“incoherent layer”) Exciton oscillator material model – extension of harmonic oscillator model
Backside reflection correction Standard modeling the measurement on thick transparent substrate (e.g. glass) will produce high-frequency oscillations (backside reflection) One need to take into account “coherence length” of the light to correct this effect
Backside reflection correction Thick transparent substrate has to be set as a layer in filmstack model (substrate is “void.mat” ) When setting the thickness of the layer – software checks if it is thick enough to be “incoherent” and warns the user