Adsorption Species of Transition Metal Ions on Silicon Wafer in SC‐1 Solution

Mori, Yoshihiro; Uemura, Kenichi; Shimanoe, Kengo; Sakon, Tadashi

doi:10.1149/1.2048696

Cited by 41 publications

(51 citation statements)

References 2 publications

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“…It has been reported that hydrolyzed iron species are formed in alkaline solutions and are highly active in the decomposition of hydrogen peroxide. At the pH of APM solution ($10.6 at 25°C), hydrolyzed iron species begin to form at the critical iron concentration of 5 Â 10 À8 mol L À1 (0.5 ppb) [22]. In previous studies aimed at determining the effect of iron concentration on hydrogen peroxide decomposition, iron was added in the Fe 3+ form to APM solutions.…”

Section: Introductionmentioning

confidence: 99%

A study of hydrogen peroxide decomposition in ammonia-peroxide mixtures (APM)

Siddiqui

Keswani

Brooks

et al. 2013

Microelectronic Engineering

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Section: Introductionmentioning

confidence: 99%

A study of hydrogen peroxide decomposition in ammonia-peroxide mixtures (APM)

Siddiqui

Keswani

Brooks

et al. 2013

Microelectronic Engineering

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“…Assuming that all the particles are cubic, with a side length of 120 nm, it is found that the surface metal concentration before precipitation would be 3.2•10 Ϫ8 mol cm Ϫ2 or 2•10 16 atom cm Ϫ2 . This is 1000 times more than the saturation point found by Mori et al 10 This fact indicates that, if there is a saturation point in the case of etching of Si in KOH, it is at least 1000 times higher than in the case of SC-1. The low contamination level of the silicon oxide due to saturation makes it difficult to characterize the contamination using SEM.…”

Section: Discussionmentioning

confidence: 58%

“…These results were found for pH 11 and at a temperature of 80°C. Mori et al 10 have also performed calculations that compare the free energy change of adsorption for Fe(OH) x (x ϭ 0 to 4͒ as a function of pH ͑0-14͒. 10 has been reached.…”

Section: Discussionmentioning

confidence: 99%

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Particle Precipitation in Connection with KOH Etching of Silicon

Nielsen

Christensen

Pedersen

et al. 2004

J. Electrochem. Soc.

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This paper considers the precipitation of iron oxide particles in connection with the KOH etching of cavities in silicon wafers. The findings presented in this paper suggest that the source to the particles is the KOH pellets used for making the etching solution. Experiments show that the precipitation is independent of KOH etching time, but that the amount of deposited material varies with dopant type and dopant concentration. The experiments also suggest that the precipitation occurs when the silicon wafers are removed from the KOH etching solution and not during the etching procedure. When not removed, the iron oxide particles cause etch pits on the Si surface when later processed and exposed to phosphoric acid. It has been found that the particles can be removed in an HCl solution, but not completely in an H 2 SO 4 -H 2 O 2 solution. The paper discusses the involved precipitation mechanism in terms of the change in free energy of adsorption, the Pourbaix diagram, the electrochemical double-layer thickness and silicon dopant type, and concentration.

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“…The metal ions adsorb on the surface silicon dioxide layer. Since the metal adsorption is controlled by a natural equilibrium, 4 the IAP wafers that are prepared in a single solution have high wafer-to-wafer uniformity.…”

Section: Introductionmentioning

confidence: 99%

Multi-batch Preparation of Standard Samples from a Single Doped Solution for Cross-checking in Surface Metal Analyses of Silicon Wafers

Mori

Uemura

2000

ANAL. SCI.

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Metallic impurities on semiconductor surfaces degrade the electrical properties of large-scale integrated circuits (LSIs). To determine such impurities, total reflection X-ray fluorescence spectrometry (TXRF) is widely used. 1 TXRF requires reference standard samples for quantification. We have proposed a method for preparing standard samples for this purpose using immersion in an alkaline hydrogen peroxide solution (IAP). 2,3 In the IAP method, base silicon wafers are immersed in an alkaline hydrogen peroxide solution in which known amounts of metal ions are doped. The metal ions adsorb on the surface silicon dioxide layer. Since the metal adsorption is controlled by a natural equilibrium, 4 the IAP wafers that are prepared in a single solution have high wafer-to-wafer uniformity.2 Because of this characteristic, the IAP wafers can also be used for crosschecking. 5,6 However, the concentrations of the surface metal are not precisely the same between different production batches, even if the concentration of added metal is the same. This situation limits the maximum number of available identical wafers to 25, which is the typical capacity of a wafer cassette. While the reason for such inconsistency is not clear, more than 25 identical samples are often required for large-scale crosscheck experiments. The aim of this paper is to propose an improved method of production that provides more than 25 identical IAP wafers. ExperimentalThe silicon wafers used in the present work were CZ n-type single crystals with polished (1 0 0) faces. The wafers were cleaned with a 0.5% hydrofluoric acid solution (r.t., 2 min), followed by a mixture of hydrochloric acid and hydrogen peroxide (standard cleaning solution-2: SC-2 7 ) before the IAP process.The baths for the IAP and rinse were made of high-purity quartz glass. That for the IAP was equipped with a circulation system. All apparatus that came into contact with either the wafers and/or the solutions were made of high-purity quartz glass or fluorocarbon polymer.All chemicals, except for the metal solutions, were of semiconductor industry grade. The metal solutions were diluted standard solutions for chemical analysis.The solution used for IAP was a 1:1:5 (volume ratio) mixture of 29% NH3, 31% H2O2, and H2O (standard cleaning solution-1: SC-1 7 ). A certain amount of Fe and Ni solution was added to the solution. After all the chemicals were poured into the bath, the solution was circulated for 5 min to become homogeneous. The pre-cleaned wafers were then immersed for 120 s at 60˚C, followed by a quick dump rinse bath (QDR, 180 s), and then an overflow bath (OFR, 270 s). The wafers were finally dried with a spindrier (SPD, 600 rpm, 270 s). The timetable is shown in Fig. 1.The NH3 and H2O2 concentrations were monitored with a continuous-flow spectrophotometric analyzer (CS-220, COS Ltd. ) every 5 min.The adsorbed metal concentration was measured with TXRF (TXRF300, Rigaku corp.). The excitation X-ray was Au-Lβ

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Adsorption Species of Transition Metal Ions on Silicon Wafer in SC‐1 Solution

Cited by 41 publications

References 2 publications

A study of hydrogen peroxide decomposition in ammonia-peroxide mixtures (APM)

A study of hydrogen peroxide decomposition in ammonia-peroxide mixtures (APM)

Particle Precipitation in Connection with KOH Etching of Silicon

Multi-batch Preparation of Standard Samples from a Single Doped Solution for Cross-checking in Surface Metal Analyses of Silicon Wafers

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