Papers

ICMCTF2008 Session B7: PVD In-Situ Characterization and Process Modeling

Wednesday, April 30, 2008 1:30 PM in Room Sunset

Wednesday Afternoon

Start	Invited?	Item
1:30 PM		B7-1 Probing Atoms and Molecules in PVD Processes M. Hecq, S. Konstantinidis, R. Snyders (Université de Mons-Hainaut, Belgium) In order to understand and to control a deposition process, diagnostic tools are necessary. In this talk, we will discuss in situ techniques used to detect atoms and molecules in the plasma and into the growing film. Optical diagnostics are the usual methods allowing to study the plasma composition. Atomic absorption spectroscopy (AAS) is usually used to measure the absolute density of sputtered atoms. We will show that, thanks to a home made emission source, this method can also be applied to measure ions. On the other hand, optical emission spectroscopy (OES) is a well known technique for the detection of radiative plasma species. Since, these species represent only a fraction of the species found in the discharge, the measured intensities have to be interpreted in term of kinetic equations involving ground and radiative states. Mass spectrometry is a sampling method for detection of species in an electric discharge, especially because it enables the detection of molecular species. Two techniques are often used: the residual gas analysis (RGA) technique enabling to measure gas particles after ionization in the spectrometer and the glow discharge mass spectrometry (GDMS) technique used to evaluate the ions present in the plasma. Due to the high sticking coefficient of the neutral sputtered species, only a combination of these two techniques leads to a complete description of the plasma chemistry. Finally, in situ evaluation of the chemical composition of the growing film can be performed by Soft X-ray Emission Spectroscopy (SXES). X-rays are produced by bombardment of electrons coming from by a modified magnetron source or from an external source. Although this technique is not widespread, it can be easily introduced in a magnetron sputtering process. Some examples of the application of these in situ techniques will be presented in the case of "hot" PVD topics such as the highly ionized magnetron discharges and the reactive sputtering process.
2:10 PM		B7-3 Langmuir Probe Measurements in a Radio Frequency (rf) Magnetron Plasma Used for the Deposition of Amorphous Silicon and Hydrogenated Amorphous Silicon S.L. Mensah, H.H. Abu-Safe, S.K. Koirala (University of Arkansas); D.G. Bhat (National Science Foundation); M.H. Gordon (University of Arkansas) The characteristics of a low pressure radio frequency (rf) magnetron plasma have been investigated using a Langmuir probe. Measurements have been taken at conditions used for sputtering amorphous silicon and hydrogenated amorphous silicon (150W rf input power, 15 sccm argon and 15 sccm hydrogen) to better explain the growth process and the effect of varying hydrogen flow rate. Previous results indicate a sudden increase in the deposition rate when hydrogen is introduced into the Ar discharge. The content of hydrogen in the film increased with increasing electron energy and flow rate up to a maximum content of 16 at %, then decreases with further increase in hydrogen flow. The decrease in content may be attributed to the measured decrease in electron density with increasing hydrogen flow. Langmuir probe studies also indicate that, with an increase in rf power, the average electron energy increases while the electron density decreases. A more detailed description will be provided in the full manuscript.
2:30 PM		B7-5 Study of a Reliable Method for the Control of Reactive Magnetron Sputtering J. Acosta, S. Sanchez, O. Salas, J. Oseguera (ITESM-CEM, Mexico); E. Bauer-Grosse (Ecole des Mines, France) The production of thin films of consistent quality by reactive magnetron sputtering requires a close control of the deposition parameters. This situation becomes critical when the hysteresis associated to this process is considered. In the present work, the optical emision spectroscopy (OES) signal for Al was controlled during the reactive magnetron sputtering of Al in an Ar+N2 atmospheres has been linked to the resulting phase formation and microstructure of the deposited films in an attempt to provide a method for the control of this process. Four experiments were performed in which the level of the OES Al signal was kept constant at different values for each experiment by varying the N2 flow. The resulting deposits were analyzed by scanning electrón microscopy linked with energy dispersive microanálisis, conventional and glancing-angle x-ray diffraction and by x-ray photoelectron spectroscopy. The results indicate that indeed, a good correlation between processing conditions and microstructure of the films can be established using plasma diagnostics. As the OES Al signal varies, there is a clear change in the morphology, density and composition of the film produced.
2:50 PM		B7-7 Analysis of Initial Conditions in Dynamic Berg’s Model S. Faddeeva, J. Oseguera (ITESM-CEM, Mexico) In order to maintain the optimal deposition conditions, it is very important to model the dynamic behavior of the reactive sputtering process adequately. One of the wide-accepted models is the Berg’s model that in case of the dynamic process is represented by the set of ordinary equations. In this paper the dependence of the dynamic Berg’s model of the deposition process on the set of initial conditions is analyzed. The results are presented in the graphical form and the suggestions for the selection of the initial conditions are given.