Degradation of metal-oxide-semiconductor devices caused by iron impurities on the silicon wafer surface

Takizawa, Ritsuo; Nakanishi, Takafumi; Ohsawa, Akira

doi:10.1063/1.339822

Cited by 45 publications

(24 citation statements)

References 2 publications

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“…The aqueous RCA process results in Mg and Ca REAs which are significantly lower than the initial unprocessed wafers. Removing the oxide is necessary because metal ions bond to the native o.xide forming metal-oxide complexes (49). Exposing the unprocessed wafers to HF(g) or HF~g)-UV/ozone had no influence on the REAs of the elements monitored.…”

Section: Discussionmentioning

confidence: 99%

XPS and SIMS Study of Anhydrous HF and UV/Ozone‐Modified Silicon (100) Surfaces

Zazzera

Moulder

1989

J. Electrochem. Soc.

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X-ray photoelectron spectroscopy and secondary ion mass spectrometry are used to study the surface chemistry of silicon single-crystal wafers. Anhydrous HF and UV/ozone processes modify the surface chemistry by altering the concentration and bonding environments of the most abundant surface atoms: Si, O, C, H, and F. Anhydrous HF in conjunction with water vapor [HF(g)] removes the silicon native oxide. Native oxides with initial thicknesses of 1 lfi~, four monolayers, are exposed to a HF(g)-H~O rinse, HF~g), and an aqueous HF-H20 rinse and are reduced to 0.4, 0.2, and 0.1 monolayers, respectively. The carbon concentration exhibits an inverse relationship with the submonolayer oxide coverage. The HF(g) process results in less than a monolayer of silicon fluorides. The silicon fluoride species decrease with air exposure resulting in mostly oxyfluorides after lh. Rinsing the fluorinated surface with H20 reduces the fluorine concentration, removes trace metal impurities initially bonded to the native oxide, and promotes initial S iO2 formation. UV/ozone exposure reduces the hydrocarbon concentration on the HF-etched surface while producing 8A, three monolayers, of SiO2. Exposing the HF(g)-treated surface to UV/ozone removes the silicon fluoride species; only oxyfluorides are observed with the ozoneinduced SiO2. The cleanest silicon surface with respect to metallic and hydrocarbon impurities was achieved with a HF etch-H20 rinse-UV/ozone oxidation process.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 169.230.243.252 ABSTRACT Crystallographic faceting of unmasked monocrystalline SiC (100) thin film surfaces during plasma etching in SF6 has been observed using scanning electron microscopy. Although the faceting produced a rough surface, Auger electron spectroscopy showed it to be very chemically clean, having less native oxide than unetched SiC. The facets were determined to be {210} planes using a combination of selected area channeling and small angle tilt measurements. The facet nucleation appears to be surface sensitive and is caused by either crystal defects or compounds formed by reaction of SF6 with adsorbed gases on the sample and chamber wall. It is proposed that the subsequent facet growth is due to a surface reconstruction that causes the {210} planes to etch slower.

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Section: Discussionmentioning

confidence: 99%

XPS and SIMS Study of Anhydrous HF and UV/Ozone‐Modified Silicon (100) Surfaces

Zazzera

Moulder

1989

J. Electrochem. Soc.

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“…1. 2Cu [2] [Overall: Si + 6HF + 2Cut2 -SiF2 + 6Ht + 2Cu] [3] Figure 2a and b show the Tafel plots obtained for silicon samples polarized in HF solutions containing different levels of copper both in the absence and presence of a surfactant. From the diagram for the Si-HF-water system (indicated by dotted lines), it may be seen that SiF2 is the most stable species at potential values more positive than -1.0 V in the pH range 0 to 7.0.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Investigation of Copper Contamination on Silicon Wafers from HF Solutions

Jeon

Raghavan

Parks

et al. 1996

J. Electrochem. Soc.

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Copper contamination of silicon wafers from 50:1 HF solutions containing 0 to 100 ppb Cu was studied using dc electrochemical techniques. As the level of copper concentration in HF solutions increased, the corrosion current density and corrosion potential of silicon as well as the amount of copper deposition were increased. Upon addition of a nonionic surfactant, the corrosion potential, corrosion current density, and the extent of copper deposition were decreased. However, the levels of deposited copper and surface roughness were dependent on sufactant concentration. When H202 was added to copper-spiked HF solutions, the open-circuit potential of silicon recovered to a value that is characteristic for silicon immersed in a mixture of H,02 and HF indicating the removal of deposited copper on silicon. InfroductionMetallic contamination of silicon wafer surfaces is an important issue because of its harmful impact on the performance of semiconductor devices. The deleterious effects ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.113.111.210 Downloaded on 2015-06-30 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.113.111.210 Downloaded on 2015-06-30 to IP

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“…3. Eventually, a quantitative correlation between the Fe concentration and the density of gate oxide defects in large area test capacitors has been established [33]. a) TEM image of plan view specimen displaying several n p diode structures.…”

Section: Iron Precipitatesmentioning

confidence: 98%