Thermal Annealing Effects on the Mechanical Properties of Plasma‐Enhanced Chemical Vapor Deposited Silicon Oxide Films

Abstract

An annealing study was performed on nonstoichiometric amorphous SiO= (x < 2) films fabricated by plasmaenhanced chemical vapor deposition (PECVD) at 300~ using Sill4 and N20 chemistry. After deposition, these layers contain hydrogen and nitrogen impurities, which were found to play a major role in the explanation of the properties of annealed films. Fourier transform infrared absorption spectra of plasma enhanced vapor deposited oxide layers annealed at elevated temperatures show approximately the same features as the spectra of thermal oxide films. This similarity demonstrates the ability of PECVD oxides to form a regular network of Si-O tetrahedrals. From distinct deviations in these spectra, the participation of Si-N bonds located within the Si-O network is concluded. The participation of Si-N bonds is also confirmed by the estimation of the activation energies in wet chemical etching studies using ammonium hydroxide water solution. The mechanical stress of the PECVD oxides clearly depends on the deposition conditions and their thermal history. With increasing annealing temperature the intrinsic stress increases until a maximum film stress value is reached between 700 and 800~ Above this temperature the intrinsic stress is continuously reduced until the total stress approaches the value of the thermal film stress. This is explained mainly by hydrogen desorption, Si-N bond formation, and SiO2 bond rearrangement processes. Depending on deposition conditions and postannealing steps, it is possible to design layers with a predefined stress.

Luminescent Devices Based on Silicon-Rich Dielectric Materials

“…The shoulder from ~1100 to ~1300 cm -1 observed in both SRO ilms has been atributed to Si-O stretching out of phase [42]. It has been reported that this shoulder is less pronounced for the suboxides compared to the stoichiometric oxide [43,44]. The absorption at 610 cm -1 due to unsaturated Si-Si bonds (phonon-phonon interactions) was observed only in M20 (SRO ilm with higher proportion of silicon precursor) showing the presence of structural imperfections at the SiO 2 /silicon nanoparticles (Si-nps) interface [45].…”

“…defect centers (ODC), E' δ (SiSi=Si) and NBOHC defects, respectively [67][68][69][70][71]. The E' δ center is one of the at least four diferent E' centers [43], which comprises an unpaired spin delocalized over ive silicon atoms and suggest the presence of very small Si-nps in the ilms.…”

The Effect of Silicon Orientation on Thickness and Chemical Bonding Configuration of SiO_xN_y Thin Films

“…These differences may be due to the change in films composition, this mean that the position of the peaks depends on the composition of the films and not on the silicon wafer crystallographic orientations. The concentration of hydrogen bonds for the two samples were estimated from the following formula [15] (1) where K is the absorption cross section, 7.4·10 -18 cm 2 for the Si-H bond and 5.3·10 -18 for the N-H bond [16], A is the area in the spectrum under the absorption peak, and t is the film thickness in nm. Fig.…”

Porous silicon used as an oxide diffusion mask to produce a periodic micro doped n++/n regions

“…The band centred at 1080 cm -1 corresponding to the Si-O stretching vibration mode widens. The shoulder in the 1100-1250 cm -1 region, corresponds to the out-of-phase Si-O stretching vibration mode [14][15][16][17]. Compared with the (ox-Si) spectrum, the Si-O x related vibration bands are largely strengthened in the (ox-PS) spectra.…”