CHEMICAL VAPOR DEPOSITION OF THIN FILM MATERIALS FOR ...

delay time of 2 seconds between spectrum taking was also set. The TDMAH adsorption was
monitored in the flowing mode (valve open) for the time range of 15 IR spectra (~6 min). After
that, the bubbler valve was closed, when the ATR cell was still under pumping, the automatic IR
spectra taking was still running one by one to monitor the surface desorption/reaction process
until the preset number of spectra is reached. The first 15 spectra taken in the flowing mode are
used to simulate the precursor pulse step in an practical ALD cycle, and the second 15 spectra in
the pumping mode were used to simulate the purging step in an ALD cycle. These ATR-FTIR
experiments were carried out under different crystal temperatures from room temperature to
250˚C. In each experiment, a spectrum of the bare crystal was taken before the TDMAH vapor
was introduced into the ATR cell and used for background subtraction.
The as used Si(100) ATR crystal was prepared to hydrogenated silicon surface by the
procedures below:
1. Sequentially ultra sonication by organic solvents acetone and methanol (2 min each).
2. Rinse with DI water for 2 min.
3. Cleaning with a 1:1:5 solution of NH4OH+H2O2+DI H2O at 80˚C for 10 min to remove the
organic contaminants.
4. Soaking in diluted BOE (buffered oxide etch, NH4F:HF = 10:1, BOE:DI water = 1:5) for 20 s
to remove the oxide layer.
5. Cleaning with a 1:1:6 solution of HCl+H2O2+DI H2O at 80˚C for 10 min to remove metallic
(ionic) contaminants.
6. Repeat step 4.
7. Rinse with DI water for 10 min.
52