The Use of 1.1.1.‐Trichloroethane as an Optimized Additive to Improve the Silicon Thermal Oxidation Technology

Abstract

Based on the pyrolysis of trichloroethene (C~HC13), also referred to as TCE, and the thermodynamic analysis of its reaction products a substitute for TCE is found. It is characterized by better physical and chemical properties and behaves as an additive during silicon oxidation identical to HC1. This chlorinated hydrocarbon, 1.1.1.-trichloroethane (referred to as C33) is used for fabrication of MOS capacitors on n-type silicon to study the properties of oxides grown with this additive. Special attention is paid to the properties influencing the performance of charge coupled devices. Storage times of 500 sec, oxide defect density of 10/cm ~, and surface-state densities lower than 5 X 109/cm 2 eV are achieved. The cleaning effect on the furnace tube yields a mobile ion density lower than 2 X 109/cm 2. The fixed oxide charge on (100) material is 5 )< 1020 cm -2. Fabrication of CCD's with this technology proves its suitability in silicon device processing.

The Distribution of Cl Impurities in SiO2 Films Produced by Thermal Oxidation of Si in Cl‐Containing Ambients

“…[12] We remind the reader that this integration describes the development of the oxide film beyond the depth x in the film. Thus Cj is the -=Si-C1 concentration at the SiO2-Si interface when this interface is at the position x. Ci is obtained via Eq.…”

“…Thus Cj is the -=Si-C1 concentration at the SiO2-Si interface when this interface is at the position x. Ci is obtained via Eq. [12]. Correspondingly, Cf is the ~Si-C1 concentration at the position x when the oxide has grown to the final thickness dox.…”

“…[12] is linear, with slope and intercept equal to kd and log C~, respectively. Figure 4 is such a replot of the data for one sample in the region close to the SiO2-Si interface (do• -x = 0-50 nm), On this plot, the reduction in measured C1 concentration over a range of two orders of magnitude is linear in the variable (x') 2.…”

“…ents was carried out by flowing a controlled amount of 02 through a bubbler containing either liquid TCA [C2H3C13] for HCl-type oxidations (12) or CC14 for C12-type oxidations (13). The oxidation procedure was similar to that previously described (9).…”

Denuded Zones in Czochralski Silicon Wafers

“…He also pointed out that if the ambient contained more than II HCl, corrosion pits would form on the wafer surface. Because of the corrosivity of HCl, some possible substitutes for HCl have been suggested, for example, trichloroethylene (TCE, C2HCI2) (Clark, 1979), and 1,1,1-trichloroethane (TCA, C2H2CI2) (Janssens and Declerck, 1978). Craven and Korb (1981), on the other hand, reported the opposite effect of an HCl-containing ambient on the formation of denuded zones.…”