Physicochemical Properties of Chemical Vapor‐Deposited Silicon Oxynitride from a SiH4 ‐  CO 2 ‐  NH 3 ‐  H 2 System

Abstract

The physicochemical properties of amorphous silicon oxynitride (SilOmND) films deposited from a SiH4-CO.2-NH~-H2 system have been investigated. The properties of CVD Si3N4 and SiO2 deposited from SiH4-NH3-H2 and SiH4-CO2-H2, respectively, were also investigated, wherever appropriate, to determine the end points of the SilO~No series. The film stress is a continuous, approximately parabolic function of silicon oxynitride composition. The SilOmN D composition also determines its resistance to oxidation in steam (950~ It is shown that a ,-~500k thick film with the composition of Si2ON2 is an adequate barrier to steam oxidation for 6 hr at 1000~ The etch rate of SilOmN, films is a function of composition in 7:1 BHF. In refluxing I4_~PO4, a peak in etch rate exists at a film composition of ~64% equivalent Si3N4. SilOmNo films deposited between 900 ~ and 1000~C densify 2-3% after "heat-treatment" at 1000~ for 2 hr and their etch rates decrease by ~50%; whereas the stress increases (more tensile) as a result of heat-treatment.Silicon oxynitride (SilOmNp) films have been chemical vapor deposited from various chemical systems (1-6), and the resulting properties have been reported(1-8). It was shown earlier by Gaind et al. (9) that the SiH4-CO2-NHs-H2 chemical system results in better process control, especially in forming Si3N4-rich oxynitride films; e.g., SilOmNp films with refractive index ~1.73 can be formed with NH3:CO2 ratio of ~6 at 900~C, whereas for other chemical systems, the NH3:oxidant ratio must be at least 50, usually ~5000 depending upon the oxidant (1-5).It is our purpose to show the similarity between the silicon oxynitrides produced by the above system and those reported in the literature. This is done by comparing physicochemical properties wherever possible with the existing data in the literature, we will at the same time be filling in gaps in the knowledge of physicochemical properties of silicon oxynitride, especially those which are important in the processing of devices (bipolar, I~'ET, etc.) which require wet etching, e.g., the oxidation barrier of oxynitrides to steam and the etch rate in refluxing phosphoric acid. There are no available data in the literature regarding these physicochemical properties.From a device-processing point of view, the importance of the effect of postdeposition "heat-treatment" (which simulates processes like diffusion or oxidation) on physicochemical properties of these dielectric films cannot be overemphasized. Thus we have investigated the effect of heat-treatment on SilOmNp film stress, etch rate, and changes in density (thickness). We have also investigated the effect of the deposition temperature on SitOmNp physicochemical properties by investigating these at two deposition temperatures, 900 ~ and 1000~ Experimental

Role of Hydrogen and Nitrogen on the Surface Chemical Structure of Bioactive Amorphous Silicon Oxynitride Films

“…Figure a shows representative XRD spectra from the highest-nitrogen- and highest-oxygen-content samples. Although X-ray spectra do not show the two broad 2θ peaks typical to amorphous Si–O–N films (i.e., 20–30 and 60–80°), it can be assumed that the SiO x sublayer dominates the spectra, resulting in one amorphous silica peak. All collected XRD spectra were found to have a similar broad peak between 20 and 40°.…”

Deposition and Chemical Composition of Silicon Oxynitride from Methylsilazane in Ammonia and Nitrous Oxide

“…The apparent reaction order of two to five with respect to the nitrous oxide may be attributed to the fact that, at kinetic limited regime, the actual partial pressure of nitrous oxide at substrate is significantly different from the initial gas composition in the bulk. k725' [2] where -C?25C(measured) X (k75 -k700) [3] 0.18 try with respect to the center of the band envelop was previously attributed to the presence of four different stretching modes of Si-N bond appearing at 838, 947, 1021, and 800 cm' with FWHM's of 146, 113, 253, and 61 cm1, respectively!8 A shoulder, at around 1160 cm' near the baseline, is due to the N-H bending mode whose stretching vibration also gave rise to a band at 3450 to 3237 cm' (not shown in Fig. 5).…”

Mechanical Stress and Electrical Properties of MNOS Devices as a Function of the Nitride Deposition Temperature

“…The dependence of the film stress upon deposition temperature in the temperature region from 600 ~ to 900~ was investigated by several authors [Ref. (10,(12)(13)(14)]. In all cases, different deposition parameters and nitride layers much thicker (2000-5000A) than the ones actually applied in memory structures were used for the investigations.…”