D1 Film Thickness Monitor

Detlef Smilgies, CHESS

Film thickness monitor

The in-situ sample chamber at D1 can be equipped with a FilMetrics F30 spectroscopic reflectometer. Thickness between 10 nm and several microns can be detected and monitored during data acquisition. Film spectra can by synchronized with X-ray images.

Starting the monitor

The thickness monitor and the Windows controll computer are inside the hutch with a remote terminal, mouse and keyboard. Double-click "scroll lock" switch, if the monitor does not show the usual XP desktop. The FilMetrics controller has to be powered on and connected to the computer, before the data acquisition software can be started.

Double-click the FilMetrics icon to start the Acquisition program FilMeasure. In this mode single spectra can be acquired and fit ted at arbitrary times, or the software can be set-up in permanent monitring mode including automated fitting of spectra.

Quick Start:

First step is calibration of the spectrometer using the "Baseline" button. For this a clean silicon wafer piece is placed in the beam and the reflectance is measured (first click). Afterwards the wafer is removed and replaced by a mirror to measure the background (second click)
Using the "Measure" button, a reflectance curve is measured and fitted.
Using "Edit structure" the fitting model can be defined / redefined (number of layers, start initial thickness, n,k, roughness, free or fixed parameter).
Using "ReAnalyze" the measured spectrum is refitted.
Using "Acquire > Start continuous measure" from the menu contibuous acquisition is started. Note that the computer will be very busy now and should be left alone. Moving the mouse back to "Acquire > Stop continuous measure", acquisition can be stopped. Please be patient to wait for the menu to drop and the computer to react, otherwise you risk crashing the program and loosing data.
After continuous aquisition data can be viewed using the "show statistics" button. Film thickness versus time is the primary information. Goodness of fit (GoF) can be used to diagnose whether the film was stable (reflectance > 30%) or dewetted (<10%). Any jump in GoF indicates something is going on. Individual spectra are stored in memory, and can be recalled by clicking the corresponding row in the table.
Individual spectra can be saved using File > Save Measured Spectrum and File > Save calculated Spectrum. For automatic saving of spectro see next section.

For more detail please consult the FilMetrics manual.

Synchronizing spectra with images

In synchronized mode the VB6 script "Data Acquirer" (start as Dline.exe on Marvin's directory) by Marvin Paik can be started, when monitor and FilMeasure are already running. The script will look for a command file generated by spec and collect and save a spectrum in the FilMetrics directory on the station computer, whenever the command file appears. The spectrum will have the same filename as the associated image.

Program inputs:

Input directory (omit final '\') > H:\FilMetrics
Input filename (incluse ext.) > fmnames
Delay (secs) > 1
> Start / Stop

Notes:

Delay controls, how often the program looks for a new file. 1 sec is typical for synchronizing with the MedOptics detector (3-4 sec read-out). Minimum is about 0.1 sec.
Start/Stop enable/disable the synchronize spectrum acqusition and saving.