Oxidation, Impurity Diffusion, and Defect Growth in Silicon—An Overview

Abstract

As a result of a large body of literature on oxidation, impurity diffusion, and defect growth in silicon, a consistent picture has emerged of oxidationenhanced diffusion (OED) and oxidation-induced stacking fault growth (OISF). It is believed that silicon self-interstitials can be generated at an oxidizing Si/SiO2 interface as a result of an incomplete half-cell reaction involving silicon and oxygen. Those interstitials that do not participate in surface regrowth participate in raising the steady-state concentration of selfinterstitials in the surface region. OED can be explained in terms of a partial interstitialcy mechanism involving the surface-generated self-interstitials. The growth of OISF will occur if the relative steady-state self-interstitial concentration around the fault exceeds the emitted concentration of interstitiais from the fault line. It is shown that this model predicts that OISF growth is limited by the production rate of self-interstitials at the Si/SiO~ interface. The retrogrowth, of OISF and the reduction of OED both occur when the concentration of generated self-interstitials decreases. The introduction of chlorine-bearing compounds into the oxidation tube can also cause retrogrowth. The reaction of chlorine with silicon at the interface creates vacancies which can recombine with generated self-interstitials and reduce their concentration. Calculations show that the chlorine compound formed at the inter= face is SIC1.Thermal oxidation of silicon is known to promote the growth of stacking faults (1-18) and dislocations (19). The stacking faults may be extrinsic or intrinsic. Extrinsic faults are formed by the insertion of an additional layer of atoms in the atom plane stacking sequence and are the type normally observed in oxidized silicon (6, 8). Stacking fault nuclei lie in the wafer prior to oxidation. Several causes of the nuclei have been observed, including mechanical damage, impurity centers, crystal growth defects, and ion implantation damage. During oxidation the stacking faults grow as two-dimensional structures lying on inclined (111) planes bounded by partial dislocations.Also occurring during oxidation is the enhanced diffusion of dopant impurities in silicon (20-25). The growth of stacking faults and the enhancement of impurity diffusion during oxidation have some similarities:1. Both the growth of oxidation-induced stacking faults (OISF) and oxidation-enhanced diffusion (OED) depend upon crystal orientation of surface planes. The rates of these effects increase in the order of (111), (110), and (100) (7, 20, 23, 26).2. Both phenomena occur more rapidly in steam than in dry oxygen (5,9,23). This correlates with the higher oxidation rate in steam.3. Both phenomena are the consequences of a longrange process. The density of bulk OISF decreases with increasing depth from the Si/SiO2 interface (27). The effect of OED has been observed to reach ~10 ~m below the interface (23).4. Both OED and OISF phenomena are suppressed in the presence of HC1 gas during oxidation (28).5. Mechanic...

Oxidation Enhanced Diffusion of Phosphorus over a Wide Range of Oxidation Rates

“…The observed power exponent, about 0.2, is much smaller than that expected in previous studies (11)(12)(13)(14)(15)(16). The observed power exponent, about 0.2, is much smaller than that expected in previous studies (11)(12)(13)(14)(15)(16).…”

“…Previous self-interstitial generation models (11)(12)(13)(14)(15) paid much attention to the interstitial flux into bulk silicon. In a previous paper (34), however, we reported that an OSF growth experiment and simulation had established that the interstitial flux into the substrate is too small to perturb the concentration at the interface.…”

“…Due to its electrical stability as an insulator, thin SiO., film is widely used as the gate material of field effect transistors (MOSFETs) and thick SiOz film used to isolate the active device region is still popular (LOCOS isolation) in state-ofthe-art integrated circuits. Also, it is widely accepted that excess self-interstitials are generated at the Si/SiO2 interface during thermal oxidation, which causes OED of dopants diffusing by the interstitialcy mechanism and the growth of oxidation-induced stacking faults (OSF) (10,11 Although several models have been proposed for the generation of self-interstitials and the OED effect (11)(12)(13)(14)(15)(16), the kinetics at the Si/SiO2 interface are still controversial. It is well known that the diffusion of phosphorus and boron is enhanced in an oxidizing ambient--so-called oxidation enhanced diffusion (OED) (1-7)--while the diffusion of antimony is retarded (ORD) (8,9).…”

Nucleation, growth and retrogrowth of oxidation induced stacking faults in thin silicon-on-insulator

“…[25][26][27] Although there are some differences in the approach taken by different authors, the most accepted one is that retrogrowth of OISFs occurs at high temperatures (1240°C) or long oxidation times (> 10 h) because the self-interstitial supersaturation (S I ) is suppressed by point defect recombination. [25][26][27] Although there are some differences in the approach taken by different authors, the most accepted one is that retrogrowth of OISFs occurs at high temperatures (1240°C) or long oxidation times (> 10 h) because the self-interstitial supersaturation (S I ) is suppressed by point defect recombination.…”

A Model for Boron Deposition in Silicon Using a BBr3 Source

“…The glass transition temper-Key words: positive electron resist, methacrylonitrile, trichloroethyl, methacrylate, copolymer. ature (Tg) of PMCN is 120~ (2), which is higher than the Tg of PMMA, which is I00~ Further, it has been shown that PMCN is one of the few aliphatic vinyl polymers that has high plasma etch resistance (3).…”