Investigation of the Copper Gettering Mechanism of Oxide Precipitates in Silicon

Kissinger, G.; Kot, Dawid; Klingsporn, Max; Schubert, Markus Andreas; Sattler, Andreas; Müller, Timo

doi:10.1149/2.0151509jss

Cited by 26 publications

(35 citation statements)

References 35 publications

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“…By this technique, a lateral resolution of better than 1.5 nm has been already demonstrated. 40 The silicon plasmon ratio mappings obtained by this technique display the silicon nanostructure in the nc-SiO x :H layers as shown in The HRTEM examinations of the nanostructure of ncSiO x :H layers validate the presence of silicon nanocrystals. An HRTEM image of a cross-sectioned nc-SiO x :H type B layer deposited at 1067 Pa is presented in Fig.…”

Section: Nanostructurementioning

confidence: 78%

Resolving the nanostructure of plasma-enhanced chemical vapor deposited nanocrystalline SiOx layers for application in solar cells

Klingsporn

Kirner

Villringer

et al. 2016

Journal of Applied Physics

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Nanocrystalline silicon suboxides (nc-SiO x ) have attracted attention during the past years for the use in thin-film silicon solar cells. We investigated the relationships between the nanostructure as well as the chemical, electrical, and optical properties of phosphorous, doped, nc-SiO 0.8 :H fabricated by plasma-enhanced chemical vapor deposition. The nanostructure was varied through the sample series by changing the deposition pressure from 533 to 1067 Pa. The samples were then characterized by X-ray photoelectron spectroscopy, spectroscopic ellipsometry, Raman spectroscopy, aberration-corrected high-resolution transmission electron microscopy, selected-area electron diffraction, and a specialized plasmon imaging method. We found that the material changed with increasing pressure from predominantly amorphous silicon monoxide to silicon dioxide containing nanocrystalline silicon. The nanostructure changed from amorphous silicon filaments to nanocrystalline silicon filaments, which were found to cause anisotropic electron transport. Published by AIP Publishing. [http://dx

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Section: Nanostructurementioning

confidence: 78%

Resolving the nanostructure of plasma-enhanced chemical vapor deposited nanocrystalline SiOx layers for application in solar cells

Klingsporn

Kirner

Villringer

et al. 2016

Journal of Applied Physics

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“…1 In both cases, between SiO 2 existing in the center of the precipitate and in the oxide layer and Si of the matrix and the substrate a suboxide region of 2-3 nm was found. These results were obtained by electron energy loss spectrometry (EELS) carried out by scanning transmission electron microscopy (STEM).…”

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confidence: 90%

Investigation of the Composition of the Si/SiO₂Interface in Oxide Precipitates and Oxide Layers on Silicon by STEM/EELS

Kissinger

Schubert

Kot

et al. 2017

ECS J. Solid State Sci. Technol.

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We investigated thermal oxide layers of different thickness on (100) and (111) silicon substrates by STEM/EELS to determine the stoichiometry profiles and compared these with stoichiometry profiles of plate-like and octahedral oxide precipitates in silicon. It was found that the stoichiometry of SiO x (x = 2) cannot be reached if the oxide layer thickness is lower than 10 nm for thermal oxides grown at 900 • C. This is due to an interface layer of equal maximum slope of x for all oxide layers. The slope of x is the change in stoichiometry with position and was obtained from fitting by sigmoid functions. Similar results were found for the oxide precipitates in silicon. However, there are arguments which question the slope determined via the low loss EEL spectra and the maximum x value could be closer to 2 in reality. On a sample with an oxide layer of 13.9 nm thickness we compared stoichiometry profiles obtained from the plasmon region and the Si-K 2,3 and O-K ionization edges. The width of the interface measured on stoichiometry profiles decreases with increasing energy loss and is lowest for the O-K ionization edge with a width of 1. In a previous work, we found that both the interface between an oxide precipitate and the surrounding silicon matrix and the interface between a silicon substrate and a thermal oxide layer are of the same nature.1 In both cases, between SiO 2 existing in the center of the precipitate and in the oxide layer and Si of the matrix and the substrate a suboxide region of 2-3 nm was found. These results were obtained by electron energy loss spectrometry (EELS) carried out by scanning transmission electron microscopy (STEM). In the low loss region, it is possible to distinguish between Si, SiO, and SiO 2 which all exhibit different maxima of the plasmon loss energy. By deconvolution, the local composition of the phase can be determined with the help of reference spectra of the three components.The stoichiometry of the oxide precipitates (SiO x ) was debated for a long time and application of different methods on different samples containing oxygen precipitates resulted in different values for x ranging from 1 to 2. Recently, it was demonstrated by applying several direct and indirect methods that the oxide precipitates consist of SiO 2 .2 Inspired by the results in Ref. 1 and 2, a layer model was proposed explaining the different experimental values for x for oxide precipitates of different geometry.3 Especially, for plate-like precipitates with a small aspect ratio the lower x values could be explained assuming that they consist of SiO 2 surrounded by a 2 nm SiO shell. However, neither is it known until now if all oxide precipitates consist of SiO 2 in the center nor is it known how thick the suboxide region for oxide precipitates grown at different temperature and time is. It needs to be mentioned that the suboxide region is not a layer of SiO composition but a profile of x increasing from the silicon matrix to the SiO 2 core. The impression of a layer just stems from the analysis of ele...

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“…[2][3][4] It was also demonstrated that metallic impurities can be effectively trapped at oxygen precipitates in the process of gettering. [5][6][7][8][9] All these features of the oxygen precipitates require the control of precipitation in the production process of silicon devices. However, this cannot be optimally executed if the features of oxygen precipitates like their composition are not fully known.…”

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confidence: 99%

Current Stage of the Investigation of the Composition of Oxygen Precipitates in Czochralski Silicon Wafers

Kot

Kissinger

Schubert

et al. 2017

ECS J. Solid State Sci. Technol.

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In this work, we look on the current stage of the investigation of the composition of oxygen precipitates obtained with the help of different techniques. Moreover, we present our recent and new investigation of the composition of oxygen precipitates carried out by means of energy dispersive X-ray spectroscopy, electron energy loss spectroscopy, and Fourier transform infrared spectroscopy. The FTIR spectra measured at liquid helium temperature are compared with the spectra simulated on the basis of experimental results obtained by scanning transmission electron microscopy. Oxygen precipitates formed in Czochralski (CZ) silicon wafers in consequence of the thermal treatment were investigated since many decades (see e.g. Ref. 1). The main reason why so much effort was directed toward these defects was the impact which they have on integrated circuits and the properties of the silicon wafer itself. Oxygen precipitates can increase the resistivity of CZ silicon, change the wafer strength and cause warpage of the wafers. [2][3][4] It was also demonstrated that metallic impurities can be effectively trapped at oxygen precipitates in the process of gettering. [5][6][7][8][9] All these features of the oxygen precipitates require the control of precipitation in the production process of silicon devices. However, this cannot be optimally executed if the features of oxygen precipitates like their composition are not fully known. In spite of the wide knowledge about oxygen precipitation, the composition of oxygen precipitates SiO x still remains under ongoing discussion. This is due to the different x values varying from x = 1 to x = 2 which can be found in the literature. [10][11][12][13][14][15][16][17][18][19][20] In 1986, Skiff et al. investigated plate-like precipitates by electron energy loss spectroscopy (EELS) in the near-edge and ionization edge range. 10 The composition which they found was SiO 0.95 . At the beginning of the 90ies, Borghesi et al. modeled Fourier transform infrared spectroscopy (FTIR) spectra by an effective medium approach and concluded that the absorption band of precipitates at 1230 cm −1 can be well reproduced if SiO 1.8 is used.11 However, in 1995 Vanhellemont investigated the growth kinetics of oxygen precipitates based on the solubility and diffusivity of oxygen in silicon using precipitate sizes determined by transmission electron microscopy (TEM). He demonstrated that the precipitated phase is closer to SiO than to SiO 2 .12 The later works, exploiting again FTIR spectroscopy and effective medium theory for the determination of the composition of the oxygen precipitates and carried out by De Gryse et al., confirmed the thesis of Vanhellemont. In the beginning the authors obtained SiO x with x = 1.1-1.2 but in their more recent work they modified the algorithm and concluded that the precipitated phase behaves optically as a mixture of amorphous silicon and amorphous SiO 2 .13,14 Meduňa et al. investigated the composition of oxygen precipitates in silicon wafers characterized by different th...

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Investigation of the Copper Gettering Mechanism of Oxide Precipitates in Silicon

Cited by 26 publications

References 35 publications

Resolving the nanostructure of plasma-enhanced chemical vapor deposited nanocrystalline SiOx layers for application in solar cells

Resolving the nanostructure of plasma-enhanced chemical vapor deposited nanocrystalline SiOx layers for application in solar cells

Investigation of the Composition of the Si/SiO₂Interface in Oxide Precipitates and Oxide Layers on Silicon by STEM/EELS

Current Stage of the Investigation of the Composition of Oxygen Precipitates in Czochralski Silicon Wafers

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Investigation of the Copper Gettering Mechanism of Oxide Precipitates in Silicon

Cited by 26 publications

References 35 publications

Resolving the nanostructure of plasma-enhanced chemical vapor deposited nanocrystalline SiOx layers for application in solar cells

Resolving the nanostructure of plasma-enhanced chemical vapor deposited nanocrystalline SiOx layers for application in solar cells

Investigation of the Composition of the Si/SiO2Interface in Oxide Precipitates and Oxide Layers on Silicon by STEM/EELS

Current Stage of the Investigation of the Composition of Oxygen Precipitates in Czochralski Silicon Wafers

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Investigation of the Composition of the Si/SiO₂Interface in Oxide Precipitates and Oxide Layers on Silicon by STEM/EELS