A Highly Sensitive Determination of Bulk Cu and Ni in Heavily Boron-doped Silicon Wafers

Lee, Sung-Wook; Lee, Sang-hak; Kim, Young-hoon; Kim, Jayoung; Hwang, Don-Ha; Lee, Bo-Young

doi:10.5012/bkcs.2011.32.7.2227

Cited by 4 publications

(4 citation statements)

References 17 publications

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“…Thus the probability of nickel adsorption and subsequent diffusion of the nickel in higher doped wafer is found to be greater compared to lightly boron-doped wafer. 9 Significant reduction of etch rate of heavily boron-doped wafer by caustic solutions is also reported. 4 This observation is explained by an energy band model.…”

Section: Resultsmentioning

confidence: 95%

“…The mechanism for such difference in nickel contamination behavior is explained by energy band model. 9 Furthermore, higher level of nickel adsorption is observed from NaOH solution compared to KOH solution. Possible explanation for such difference in nickel adsorption is discussed.…”

Section: Resultsmentioning

confidence: 97%

“…8 Nickel diffusivity in boron-doped silicon at the caustic etch temperature is found to be higher than etch rate which furthermore results into bulk contamination from deposited silicon. 9 Mechanism of electron transfer in precipitation of nickel is further supported by the fact that significant reduction of nickel precipitation is achieved on wafer during caustic etching process by the addition of hydrogen peroxide. As indicated above, increased reduction potential from the addition of hydrogen peroxide to KOH solution inhibits nickel deposition from the solution.…”

Section: Resistivity Of Silicon-a Correlation Exists Between Resistiv...mentioning

confidence: 94%

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Nickel Contamination from Caustic Etching of Silicon Wafers

Sinha¹

2018

ECS J. Solid State Sci. Technol.

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The behavior of nickel adsorption during caustic etching of boron-doped silicon wafer is investigated. Caustic solutions considered for investigation are sodium hydroxide (NaOH) and potassium hydroxide (KOH). In addition to the amount of nickel present in the caustic solution, the degree of nickel contamination of the wafer is also affected by the dopant concentration, temperature and nature of the caustic solutions used. Control of nickel contamination by various additives to the caustic solution is found to be effective and comparable to each other. The possible mechanism of nickel adsorption is explained by considering metal stability in specific caustic solution and the electro-chemical potential Wet etching of silicon by caustic solution is extensively used, because of its high anisotropic etch rate, in both silicon wafer manufacturing and device fabrication. Use of KOH in fabrication of microelectricalmechanical system (MEMS) is widespread.1 Strong dependence of silicon etch rate on crystal orientation (<100> vs. <111) and on silicon doping level is observed in caustic etching of silicon. This makes caustic etching a desirable candidate for manufacturing silicon structure requiring anisotropic etching. Numerous studies have been done to explain the etch rate, primarily in KOH solution, in terms of its dependence on temperature, dopant type and concentration, crystal orientation as a function of KOH concentration. 2-4In wafer manufacturing, silicon wafers are subjected to various processes such as lapping, grinding and edge profiling which generate surface defects caused by the stress induced from such processes. Subsequent caustic or acid etching is required to remove these defects. However, nickel contamination by adsorption is observed on the surface and in the bulk during the etching process. Continued reduction of overall metal contamination is proposed in technology roadmaps to improve device yield and performance.5 Deposition of metal ions during acid etching is explained based on the electrochemical potential of the ion compared to the semiconductor surface. In general, metal ions with a higher potential than the semiconductor are irreversibly adsorbed on the surface compared to one with lower electrochemical potential. 6 Higher etch rate, in addition to better flatness, back-side geometry, cost and operation safety is achieved in caustic etching of wafer compared to an acid etch process. 7Commercially available caustic solutions like sodium hydroxide and potassium hydroxide normally used as etchants typically contain a significant quantity of nickel, copper, and other metals. Some of these metals can diffuse easily into the bulk of the silicon wafer during the etching process. The caustic solutions namely NaOH and KOH are used for investigation of nickel adsorption on boron doped (<100>) silicon wafers with varying resistivity. The influence of caustic etchant type, wafer doping level and temperature on metal adsorption is discussed. A possible mechanism for nickel adsorption is discussed along wit...

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Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 97%

Section: Resistivity Of Silicon-a Correlation Exists Between Resistiv...mentioning

confidence: 94%

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Nickel Contamination from Caustic Etching of Silicon Wafers

Sinha¹

2018

ECS J. Solid State Sci. Technol.

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“…On the other hand, nickel diffusivity is found to be comparable to etch rate with lightly boron-doped silicon wafer. Thus the probability of nickel adsorption and subsequent diffusion of the nickel in higher doped wafer is found to be greater compared to lightly boron-doped wafer (10). Significant reduction of etch rate of heavily boron-doped wafer by caustic solutions is also reported (4).…”

Section: Temperature Of Caustic Solutionmentioning

confidence: 99%

Nickel Contamination from Caustic Etching of Silicon Wafers

Sinha¹

2017

ECS Trans.

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The behavior of nickel adsorption during caustic etching of borondoped silicon wafer is investigated. Caustic solutions considered for investigation are sodium hydroxide (NaOH) and potassium hydroxide (KOH). In addition to the amount of nickel present in the caustic solution, the degree of nickel contamination of the wafer is also affected by the dopant concentration, temperature and nature of the caustic solutions used. Control of nickel contamination by various additives to the caustic solution is found to be effective and comparable to each other. The possible mechanism of nickel adsorption is explained by considering metal stability in specific caustic solution and the electro-chemical potential of the silicon surface in presence of etching solution.

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Fast and Slow Stages of Lifetime Degradation by Boron–Oxygen Centers in Crystalline Silicon

Schmidt

Bothe

Voronkov³

et al. 2019

Physica Status Solidi (b)

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A conflict between previous and recently published data on the two‐stage light‐induced degradation (LID) of carrier lifetime in boron‐doped oxygen‐containing crystalline silicon is addressed. The previous experiments showed the activation of two boron–oxygen recombination centers with strongly differing recombination properties for the fast and slow stages of LID, whereas more recent studies found only a single center for both stages. To resolve this controversy, the historic silicon samples of these previous examinations are re‐examined in this study after more than one decade. It is found that, in the historic samples, the fast stage can be either described by two different centers or a mixture of the two, depending on the duration of previous dark annealing. A possible solution is suggested based on the involvement of different activating impurities in the boron–oxygen defect. In dark‐annealed samples, the defect consisting of boron, oxygen, and the activation impurity is present in two latent configurations, which reconfigure during LID at a fast and a slow stage. In the examined historic silicon samples, which did not undergo a gettering pretreatment, a significant concentration of an additional boron–oxygen defect with a different kind of activating impurity attached exists. The historic and modern results are thus reconciled.

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A Highly Sensitive Determination of Bulk Cu and Ni in Heavily Boron-doped Silicon Wafers

Cited by 4 publications

References 17 publications

Nickel Contamination from Caustic Etching of Silicon Wafers

Nickel Contamination from Caustic Etching of Silicon Wafers

Nickel Contamination from Caustic Etching of Silicon Wafers

Fast and Slow Stages of Lifetime Degradation by Boron–Oxygen Centers in Crystalline Silicon

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