In the case of the semi-insulating polycrystalline silicon ͑SIPOS͒ SiO x low-pressure chemical vapor deposition ͑LPCVD͒ process, the influence of the two most important operating parameters, gas inlet composition and process temperature, on the evolutions of the deposition rate and of the film oxygen content along the reactor load and on-wafer, has been experimentally studied. This set of experimental results was then used as a database to develop a new kinetic model, using a local numerical simulation code for LPCVD reactors, named CVD2. This new kinetic model certainly summarizes numerous poorly known gas phase and surface reactions involved in SIPOS deposition. Its validation has been successfully performed by comparison with specific experimental data, both along the load and on-wafer. An efficient mathematical tool is then available to better control and optimize the performances of SIPOS low-pressure deposition processes.The acronym SIPOS, for semi-insulating polycrystalline silicon, is used to refer to silicon thin films doped with oxygen. These layers are characterized by a global average composition SiO x with x varying between 0 ͑polycrystalline silicon layer͒ and 2 ͑stoichiometric oxide͒. Because of its efficiency in improving the breakdown characteristics of high-voltage bipolar transistors when used as a passivating layer, 1,2 SIPOS has been dealt with in many studies during the last several years. This material has a complex internal nanometer-scale organization and is composed of several phases. There are reports of silicon both in the amorphous form 3-6 and as small microcrystallites 3,7,8 of silica 3 and substoichiometric oxide SiO x . Many compositions have been experimentally obtained such as SiO, 9 Si 2 O 3 , 9 SiO 0.86 , 3 or SiO 1,4 , 7 depending on the operating conditions. The quantity of oxygen atoms incorporated into the layer during the deposition mainly determines the physicochemical 10 and electrical properties of the layer, 3,8,11,12 and, consequently, any variation of this oxygen content can decrease the entire component reliability. This is why a strict control of the oxygen content incorporated during deposition must be exerted. The most widely used process in the microelectronic industry for SIPOS elaboration is chemical vapor deposition under low-pressure conditions ͑LPCVD͒, because it can process conveniently several tens of wafers by run. The SIPOS process deposits results from the reactions of two gaseous sources, usually silane (SiH 4 ) and nitrous oxide (N 2 O). It is well known that the oxygen concentration can be varied by modifying the entrance gas composition 8,10 and that it is a nonlinear function 10 of the molar fraction ␥ ϭ N 2 O/SiH 4 . The process temperature has also been found to exert an important influence on the layer composition. 10 In addition, heterogeneities on any of the wafers and from wafer to wafer all along the load have been observed 13 which limits the number of wafers per run and, hence, the reactor productivity. For instance, a SIPOS layer grown ...