Kinetics and Mechanism of Carbon Incorporation in Ultrathin Silicon-Based Dielectric Films

Abstract

The effect of various processing conditions on the extent of adsorption of organics and incorporation of carbon in normalSi/SiO2 during thermal oxidation is investigated. The key parameters studied are preoxidation cleaning, temperature-ramp rate and ambient, gas-phase impurity concentration, and the presence of moisture. A novel method based on the catalytic oxidation of organics is developed to monitor and characterize the outgassing of organics. Results show that SC1-last surfaces adsorb more polar organics than do HF-last surfaces; this results in a higher amount of carbon incorporation. HF-last surfaces, however, retain a larger fraction of the adsorbed organics. Addition of oxygen to the temperature-ramp ambient reduces the extent of carbon incorporation. The kinetics and mechanisms of carbon incorporation in normalSi/SiO2 substrates are investigated. A reaction model based on the competitive processes of desorption, readsorption, decomposition, oxidation, and chemisorption of the adsorbed organics is developed. This model provides a better understanding of one of the key aspects of defect formation in silicon-based dielectric thin films. © 2002 The Electrochemical Society. All rights reserved.

Quantitative analysis of supported membrane composition using the NanoSIMS

“…The secondary ion signal of another isotope of the same element is commonly employed as the internal standard reference, for example, 12 Although surface contamination is also expected to produce 12 C -secondary ions, 12 C -was experimentally determined to be an appropriate internal standard (see below). Carbon is a common contaminant in silicon wafers introduced throughout the substrate fabrication process [41]. Although there may be wafer-to-wafer variations, the level is expected to be quite constant across the surface of our 5 x 5 mm chips, and this provides a standard.…”

Susceptibility of SiO2, ZrO2, and HfO2 dielectrics to moisture contamination

“…It results in an apparent increase in the film thickness, thereby deteriorating the precision performance of ellipsometers. Rana et al (2002) assert that moisture also aggravates organic contamination of these surfaces. Therefore, moisture contamination of wafer surfaces during critical processing steps such as gate stack formation can be detrimental.…”

Mechanistic Study of Surface Contamination of Dielectric Oxides Using Isotope Labeling

“…[1][2][3][4][5] The most detrimental impact of organic contamination in semiconductor processing is gate oxide deterioration. [6][7][8][9] The performance of metal oxide semiconductor field effect transistors (MOSFETs) is adversely affected by moisture and organic contamination. The presence of moisture and organics in the ambient during the formation of gate stacks can increase the likelihood of dielectric breakdown and leakage current.…”

“…Organics are also found in significant amounts in a cleanroom atmosphere. − A variety of organic molecules outgas from paints, bottles, containers, chemicals, particle filters, and polymeric wafer carriers. They can change wetting properties of surfaces, cause hazing of wafers, assist particle formation, and induce unintentional doping of surfaces. − The most detrimental impact of organic contamination in semiconductor processing is gate oxide deterioration. − The performance of metal oxide semiconductor field effect transistors (MOSFETs) is adversely affected by moisture and organic contamination. The presence of moisture and organics in the ambient during the formation of gate stacks can increase the likelihood of dielectric breakdown and leakage current.…”

“…As the gate dielectric shrinks, the effects of molecular contaminants become even more significant. It is well-known that organic contamination of Si surfaces can lead to the formation of silicon carbide during subsequent thermal processing, eventually resulting in degradation of the gate oxide quality. − Moisture contamination causes the formation of electron traps in ultrathin gate oxides . Molecular contamination can also adversely affect the adhesion of films for gate stack formation.…”