Calibrated Contamination Spiking Method for Silicon Wafers in the 1010 – 1012   Atom / cm2 Range

Hölzl, R.; Range, K.‐J.; Fabry, L.; Huber, D.

doi:10.1149/1.1391922

Cited by 24 publications

(6 citation statements)

References 31 publications

(35 reference statements)

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“…It could be used to more precisely engineer the level of contaminants intentionally spun onto doped test wafers. 23,24 It could be used to estimate the translation of contaminants in bulk chemical onto the surface of wafers during spin coating. Or, it could be used along with surface spectroscopic techniques, such as total reflection X-ray fluorescence (TXRF), [25][26][27] to estimate low levels of contaminants present in bulk chemicals.…”

Section: Resultsmentioning

confidence: 99%

Translation of Dilute Soluble Contaminants to Wafers during Spin Coating

Extrand

Moon

Monson

2014

ECS J. Solid State Sci. Technol.

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In this work, we developed a mathematical model to quantify the translation of soluble contaminants from bulk liquid chemicals to the surface of wafers during spin coating. We tested various kinds of liquids, including those used in application of photo-resist as well as wafer cleaning and surface preparation. To validate the model, dilute polymer solutions with different concentrations were deposited onto spinning wafers, where they flowed outward and then evaporated. We used ellipsometry to determine the mass of contaminant left behind on the wafers. The levels of deposited contaminants increased with concentration in the bulk liquid and decreased with spin speed. The model well predicted the experimental data and thus allows for estimation of contaminant translation during spin coating.As the quest for smaller, faster and less expensive electronic devices marches on, circuitry in those devices is also shrinking and becoming more sensitive to particles, metals and other forms of contamination. While the semiconductor industry generally has done an excellent job of understanding the purity of the materials and chemicals used in fabricating electronic devices, how impurities translate from equipment, components and chemicals through fabrication processes and onto wafers is less clear.Spin coating is a common process that brings liquid chemicals into direct contact with wafers. It is used to apply photo-resist, to clean, etch and dry wafers, as well as to evaluate the cleanliness of liquid filters, fluid handling components and systems. Application of photoresist by spin coating has been carefully studied. 1-17 Previous work describes experiments and modeling of relatively concentrated polymer solutions where the solvent is an organic liquid with low surface tension and high boiling point. 2-7,10,11 However, liquids with a much broader range of properties are used in semiconductor processes and contaminants in those liquids are typically present at very low levels. Therefore, the aim of this work is to develop a mathematical model for quantifying the translation of low levels of soluble contaminants from liquids to wafers during spin coating and validate with experiments. TheoryTo quantify the translation of more dilute concentrations of soluble contaminants from bulk chemicals to the surface of wafers, a working model is needed. Consider the following scenario. A volatile liquid containing soluble, non-volatile contaminant is dispensed onto a wafer that is spinning at a constant rotational velocity of ω. Excess liquid is immediately flung from the spinning wafer. The remaining liquid layer flows outward under centrifugal force. We assume the contaminants simply move along with the liquid. Once outward flow of the spinning liquid layer slows and evaporation takes over, the contaminant is deposited onto the surface of the wafer.To construct our working equation, we begin with the classic analysis of liquid on a spinning disk by Emslie, Bonner and Peck. 1 Assume that the process is isothermal, the liquid is Newtonia...

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Section: Resultsmentioning

confidence: 99%

Translation of Dilute Soluble Contaminants to Wafers during Spin Coating

Extrand

Moon

Monson

2014

ECS J. Solid State Sci. Technol.

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“…Ample evidence exists in the literature showing that the quantification by TXRF is very dependent on the sample microcrystallinity. [35][36][37] For the two particular cases reported in the present paper, the salt residues obtained by both techniques are inherently of a different nature. Tests where a film of KCl solution is evaporated horizontally result in a continuous residue containing on the order of 10 15 atoms/cm 2 K, while tests where a small droplet of a Ni͑NO 3 ͒ 2 is dried result in noncontinuous residues containing on the order of 2 ϫ 10 13 atoms/cm 2 Ni.…”

Section: G448mentioning

confidence: 92%

Study of the Carry-over Layer and Its Importance for Wet Processing of Semiconductor Substrates

Fyen

Mertens

2006

J. Electrochem. Soc.

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In this paper we investigate the entrainment of a liquid film by a solid as the latter is removed from a bath ͑referred to as the carry-over layer͒. This is done theoretically as well as experimentally with emphasis on its role in immersion-based processing of flat substrates such as semiconductor wafers. Existing models calculating liquid withdrawal by infinite substrates are modified to take gravitational drainage into account. The latter is important when substrates of a finite size ͑such as semiconductor wafers͒ are considered. Experiments using metal salts as tracer elements are performed to evaluate the thickness of the carry-over layer as a function of withdrawal speed and postwithdrawal drainage time. A good agreement with the drainage models is obtained, leading us to draw some qualitative conclusions concerning liquid carry-over during semiconductor wafer processing.

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“…The standard solution was composed of nitric acid solving metal (Fe, Cr, Ni, Cu, or W) z E-mail: Koichiro.Saga@jp.sony.com and their solutions were mixed and diluted to 10 ppm by ultrapure water. 9,10 The target of average metal concentration on the wafers was 2 × 10 13 atoms/cm 2 much enough to detect metals penetrating in silicon with chemical analysis and secondary ion mass spectrometry (SIMS). Fig.…”

Section: Methodsmentioning

confidence: 99%

Behavior of Transition Metals Penetrating Silicon Substrate through SiO₂and Si₃N₄Films by Arsenic Ion Implantation and Annealing

Saga¹,

Ohno²,

Shibata

et al. 2015

ECS J. Solid State Sci. Technol.

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The behavior of metals penetrating the silicon substrate through a screen SiO 2 or Si 3 N 4 film by the collision of arsenic ion and surface metals are quantitatively demonstrated. We have found using silicon step etching followed by ICP-MS and SIMS that 0.1∼8% of surface metals (Fe, Cr, Ni, Cu, and W) penetrate silicon even when implanted through screen SiO 2 film, depending on metal species and the film thickness. The surface metals on a CVD Si 3 N 4 film can also penetrate into the silicon during ion implantation and/or subsequent annealing. W is most difficult to penetrate the thermally-grown SiO 2 film, while W and Cr can easily penetrate a CVD Si 3 N 4 films. We have also found using microwave photoconductive decay measurements that recombination centers are generated in silicon by low level metal penetration even when implanted through screen Metallic contamination on silicon surfaces has a detrimental impact on the performance and yield of ULSI devices. Surface metal impurities degrade the gate oxide integrity while metal impurities dissolved in silicon cause recombination centers and these result in junction leakage, degrade retention characteristics in DRAMs, and cause dark currents in image sensors. Surface metal impurities often penetrate the silicon by thermal diffusion in ULSI processing. The diffusion behavior of these metal impurities in silicon is well-known. [1][2][3] Most metallic contamination occurs during wafer processing, particularly reactive ion etching and ion implantation 4-6 and here it has been reported that metals transported with dopant ion from an ion source or acceleration tube in ion implantation equipment can be deposited on silicon surfaces. 5,6 On the other hand, the behavior of surface metal impurities penetrating by the collision with a dopant ion has not been known. The ion implantation may assist surface metal impurities penetrating the screen films and silicon. The collided metal atoms' penetrating silicon can be prevented by screen films such as SiO 2 or Si 3 N 4 films, 7 in which the diffusion coefficients of metal impurities such as Ni and Cu are smaller than in Si. 8 In this paper, the behavior of metals penetrating the silicon substrate through a thermally grown SiO 2 or CVD Si 3 N 4 film by the collision of dopant ion and surface metals and subsequent annealing are quantitatively demonstrated. The generation of recombination centers due to the metal penetrating silicon is also discussed. ExperimentalCzochralski (CZ) Si (100), (p-type, 8-12 cm), 200 mm diam. wafers were used in this study. A group of wafers was oxidized to form silicon oxides on the surface. The thickness of the silicon oxide was 5 nm, 20 nm, 80 nm, 120 nm, and 160 nm. A Si 3 N 4 film was deposited on the surface of another group of wafers at 700• C by low pressure CVD. The thickness of the Si 3 N 4 film was 20 nm.Next, the silicon wafers were cleaned with NH 4 OH/H 2 O 2 /H 2 O mixture and HCl/H 2 O 2 /H 2 O mixture. The surfaces of the SiO 2 and Si 3 N 4 films of the wafers were hydrophilic. ...

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Calibrated Contamination Spiking Method for Silicon Wafers in the 1010 – 1012 Atom / cm2 Range

Cited by 24 publications

References 31 publications

Translation of Dilute Soluble Contaminants to Wafers during Spin Coating

Translation of Dilute Soluble Contaminants to Wafers during Spin Coating

Study of the Carry-over Layer and Its Importance for Wet Processing of Semiconductor Substrates

Behavior of Transition Metals Penetrating Silicon Substrate through SiO₂and Si₃N₄Films by Arsenic Ion Implantation and Annealing

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Calibrated Contamination Spiking Method for Silicon Wafers in the 1010 – 1012 Atom / cm2 Range

Cited by 24 publications

References 31 publications

Translation of Dilute Soluble Contaminants to Wafers during Spin Coating

Translation of Dilute Soluble Contaminants to Wafers during Spin Coating

Study of the Carry-over Layer and Its Importance for Wet Processing of Semiconductor Substrates

Behavior of Transition Metals Penetrating Silicon Substrate through SiO2and Si3N4Films by Arsenic Ion Implantation and Annealing

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Behavior of Transition Metals Penetrating Silicon Substrate through SiO₂and Si₃N₄Films by Arsenic Ion Implantation and Annealing