Effects of HCl and Cl2 additions on silicon oxidation kinetics

Meulen, Y. J. van der; Cahill, J. G.

doi:10.1007/bf02652948

Cited by 28 publications

(31 citation statements)

References 11 publications

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“…To facilitate the analysis we define an effective position x' (x') 2 = (dox -x) 2 + A(dox -x) [14] The final form of the expression is in Cf = -kd(x') 2 + In Ci [15] where as previously defined…”

Section: Discussionmentioning

confidence: 99%

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

Sheu¹,

Butler²,

Feigl³

et al. 1986

J. Electrochem. Soc.

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C1 was introduced into SiO2 films by thermally oxidizing (100) Si in either OJHC1 or O2/C12 gas mixtures at llO0~ C1 concentration vs. depth profiles in these oxide films were determined by SIMS (secondary ion mass spectrometry). Analysis of the C1 distributions shows that, after incorporation into the SiO2 network at the interface, in the bulk of the growing oxide the bonded C1 is removed from the network. This process is analyzed quantitatively as a chemical reaction in which H20 reacts to replace C1 with OH. The kinetics of this replacement reaction and of the oxide film growth determine the C1 concentration vs. depth profiles in the grown films. The replacement reaction kinetics are faster when H20 is present than when only O2 is present. This accounts for the significantly different CI profiles in HCI oxides and Cl2 oxides. These observations are consistent with previous studies of the redistribution of implanted CI in oxide films during a second oxidation step.Oxidation of Si in chlorine-containing ambients is a widely used process in preparing gate oxide films for Si devices (1). In this process C1 is incorporated into the SIO2, and is found to be segregated primarily near the Si/SiO2 interface (2-4). Recent C1 concentration vs. depth profiles determined by secondary ion mass spectrometry (SIMS) show a significant amount of C1 distributed in the oxide with increasing concentration toward the Si/SiO2 interface (5-9). One interpretation of these profiles was that the measured C1 was determined by the high temperature distribution of a mobile, diffusing C1 species (7). The authors suggested that the C1 transport was by a "field-aided" diffusion process, against the concentration gradient. However, the origin of such a field was not established. In contrast, the C1 profile was suggested to be determined by a reaction-controlled process (9, 10). This difference has not been resolved. The question will be addressed in this paper.In a previous paper, we presented a semiquantitative analysis of C1 concentration profiles measured by SIMS (11). The profiles were obtained in the course of high temperature (900~ reoxidation of thermal oxide films implanted with C1; the analysis indicated that redistribution of the implanted C1 during the reoxidation step can be controlled by either reaction or diffusion. Which process dominates depends on the concentration of mobile molecular species (H~O or O2) capable of displacing chlorine species bonded into the SiO2 network (=-Si-C1) and on the relative magnitude of forward and reverse reaction rates in the displacement reaction. In fact, the redistribution process is slow and reaction limited in dry reoxidizing ambients (of order 1 ppm H20). It is fast and possibly diffusion limited in wet ambients (more than 1% H20).Similar processes should determine the distribution of chlorine within oxide films fabricated by thermal oxidation of silicon in ambients containing HC1. Because of the gas-phase reaction of HC1 and O2, the molecular species HC1, C12, 02, and H20 will be present in ...

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Section: Discussionmentioning

confidence: 99%

“…The chemical composition of these layers has been extensively investigated by Habraken et al (14,15). Their analyses show that the layers have the stoichiometric compositions (Si/N = 0.75) and that they contain 0.15 atomic percent (a/o) chlorine and 3 a/o hydrogen.…”

Section: Methodsmentioning

confidence: 99%

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

Sheu¹,

Butler²,

Feigl³

et al. 1986

J. Electrochem. Soc.

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“…These and other studies have indicated that such chlorine additions provide certain benefits to the resulting device structures, such as alkali ion passivation, higher and more uniform oxide dielectric strength, and improved junction properties due to lower leakage (5)(6)(7)(8). Coincidentally increased oxidation rates have been observed with increasing chlorine concentration in the oxygen ambient (1)(2)(3)(4). The reported improvements in device properties are probably due in part to actual incorporation of a chlorine species in the silicon oxide and reaction of this species with impurities (8,9).…”

mentioning

confidence: 95%

“…Recent investigations concerning the oxidation kinetics of silicon in dry oxygen containing small additions of HC1 or C12 have been reported (1)(2)(3)(4). These and other studies have indicated that such chlorine additions provide certain benefits to the resulting device structures, such as alkali ion passivation, higher and more uniform oxide dielectric strength, and improved junction properties due to lower leakage (5)(6)(7)(8).…”

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confidence: 99%

Thermal Oxidation Kinetics of Silicon in Pyrogenic H 2 O and 5% HCl / H 2 O Mixtures

Deal

1978

J. Electrochem. Soc.

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The kinetics of the thermal oxidation of silicon in H20 and in 5 volume percent (v/o) HCI in H20 using a pyrogenic system have been investigated over the temperature range 900~Oxide thickness-oxidation time data, rate constants, and activation energies have been obtained for (111) and (100) oriented, 1 • 10 I~ cm -~, n-type silicon. Results obtained for oxidation in H20 are very similar to those reported previously for water bubbler systems. The addition of HCI to H20 does not increase the silicon oxidation rate as with dry O2, but the rate actually decreases apparently because of the reduced llzO vapor pressure. The HC1 also appears to reduce impurity contributions from the oxidation system.

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“…Other impurities added to the oxidizing ambient have been considered such as HCl, CIl and organic chlorine containing compounds (71)(72)(73). The literature attests to the fact that oxide charge levels are reduced and oxide reliability is enhanced through these additions.…”

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confidence: 99%

Models for the oxidation of silicon

Lewis

Irene

1986

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Since the 1960’s many adaptations to the linear parabolic model for silicon oxidation have been proposed. For the purposes of process engineering, curve fitting procedures which are sometimes devoid of physical content but numerically precise are employed. However, a truly unified physical model which is in quantitative accord with all known facts is still lacking. In this review we will discuss the ‘‘facts’’ and newer models.

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Effects of HCl and Cl2 additions on silicon oxidation kinetics

Cited by 28 publications

References 11 publications

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

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

Thermal Oxidation Kinetics of Silicon in Pyrogenic H 2 O and 5% HCl / H 2 O Mixtures

Models for the oxidation of silicon

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