Showing papers by "Gerald Lucovsky published in 1989"

Effects of thermal history on stress‐related properties of very thin films of thermally grown silicon dioxide

Abstract: This paper presents studies of the infrared (IR) absorbance and the intrinsic stress in thermally grown very thin films (60 to 700 A) of SiO2. These data are combined with previously obtained data for thicker thermally grown films (∼1300 A) to study the variation in intrinsic growth stress close to the Si/SiO2 interface. The combined data indicate that the intrinsic stress at Si/SiO2 interfaces extrapolates to the same relatively high values for oxides grown at 700 and 1000 °C, and that the distribution of Si–O–Si bond angles close to the Si/SiO2 interface, as deduced from the IR data, is quantitatively different than in the bulk of the oxide film. These two observations are explained in terms of a model based on a temperature dependent viscoelastic relaxation of the oxide stress. This model emphasizes differences in the thermal history of the SiO2 near the Si/SiO2 interface, as compared to the SiO2 that is well removed from that interface and is in the bulk of the film and/or close to the ‘‘top’’ surface of the film. The observed differences between the 700 and 1000 °C bulk oxides, and the associated Si/SiO2 interfaces are explained in terms of a renormalized time scale that is defined by the ratio of the growth time to the viscoelastic relaxation time at the growth temperature.

Ultrafast recombination and trapping in amorphous silicon

Abstract: We have studied time-resolved reflectivity changes induced by femtosecond laser pulses in a-Si and a-Si:H thin-films. By varying pump-power, we have identified a non-radiative recombination process which controls the free-carrier density, N, on a picosecond time scale for N>5 ×1018cm−3 in a-Si:H and >5×1019 cm−3 in a-Si. At lower carrier densities, transients are controlled by trapping of free-carriers.

Multichamber Integrated Deposition System For Silicon Based Dielectric Films

Abstract: This paper discusses the design and operation of a multichamber integrated processing system with in situ surface analysis capabilities. The system has been designed specifically for the deposition of silicon based dielectric thin films by the process of remote plasma-enhanced chemical-vapor deposition (Remote PECVD), and for the formation of microelectronic device heterostructures. In order to achieve these objectives the system includes the following: (1) two substrate-introduction load-lock chambers; (2) a semiconductor substrate processing chamber; (3) a dielectric deposition chamber, specifically configured for the remote PECVD process; (4) a surface analysis chamber including Reflection High Energy Electron Diffraction (RHEED) and Auger Electron Spectroscopy (AES); and (5) inter-chamber substrate transfer in a UHV compatible environment. We will discuss the deposition chamber in some detail and describe the way in which it is designed to meet the requirements for the Remote PECVD process reactions. We also describe an auxiliary deposition/analysis system, which provides both deposition process diagnostics, Mass Spectrometry (MS) and Optical Emission Spectroscopy (OES), and thin film deposition by Remote PECVD. These two systems taken together have provided a research capability for: (1) identifying the deposition process reactions; and (2) fabricating elementary microelectronic device structures, such as MOS and/or MIS capacitors.