• Korean Journal of Materials Research
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• v.16 no.2
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• pp.80-84
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• 2006

The removal efficiency of Cu and Fe contaminants on the silicon wafer surface was examined to investigate the effect of cleaning solutions on the behavior of metallic impurities. Silicon wafers were intentionally contaminated with Cu and Fe solutions by spin coating and cleaned in different types of cleaning solutions based on $NH_4OH/H_2O_2/H_2O\;(SC1),\;H_2O_2/HCl/H_2O$ (SC2), and/or HCl/$H_2O$ (m-SC2) mixtures. The concentration of metallic contaminants on the silicon wafer surface before and after cleaning was analyzed by vapor phase decomposition/inductively coupled plasma-mass spectrometry (VPD/ICP-MS). Cu ions were effectively removed both in alkali (SC1) and in acid (SC2) based solutions. When $H_2O_2$ was not added to SC2 solution like m-SC2, the removal efficiency of Cu impurities was decreased drastically. The efficiency of Cu ions in SC1 was not changed by increasing cleaning temperature. Fe ions were soluble only in acid solution like SC2 or m-SC2 solution. The removal efficiencies of Fe ions in acid solutions were enhanced by increasing cleaning temperature. It is found that the behavior of metallic contaminants as Cu and Fe from silicon surfaces in cleaning solutions could be explained in terms of Pourbaix diagram.

• Journal of the Semiconductor & Display Technology
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• v.10 no.1
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• pp.51-55
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• 2011

The surface passivation is one of the important methods that can improve the efficiency of solar cells and can be classified into two methods: wet-chemical passivation and film passivation. In this paper, chemical HF treatment were employed for the passivation of n-type silicon wafers and their effects were studied. To investigate film passivation effects, the silicon nitride films were also deposited by PECVD (plasma-enhanced chemical vapor deposition) on n-type silicon wafers treated with chemical HF. The minority carrier lifetime measurements were used for evaluation of the passivation characteristics in the all experiments steps. We confirmed that the minority carrier lifetime was improved with chemical HF treatment due to passivation effects by H-termination.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.05a
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• pp.128-133
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• 1999

In recent years, LSI devices have become more powerful and lower-priced, caused by a development of various wafer materials and an increase in the diameter of wafers. On the other hand, these have created some serious problems in manufacturing of wafers because materials used as semiconductor substrate are very brittle. In view of this fact, there are some trials to apply shear-mode(or ductile-mode) grinding for efficient manufacturing of semiconductor wafers instead of conventional lapping process. In fact grinding process that has not only more excellent degree of accuracy but also more adaptable to fully automated manufacturing than lapping, is already used in Si machining field. This paper described the elementary studies to establish the grinding technology of wafers. First, we investigated the variation of grinding force and the transition of grinding mode as various grinding conditions. Then, it was inspected that the change of grinding force affected the integrity such as the topography and the roughness of ground surfaces, and led to the chemical defects generation and distribution in damaged layer. The degree of defects was estimated by FT-IR(Fourier Transformed Infrared) Spectroscopy and Auger Electron Spectroscopy

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.185-186
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• 2005

Intrinsic gettering is usually used to improve wafer quality which is an important factor for reliable ULSI devices. The two-step annealing method was adopted in order to investigate interactions between oxygens and secondary defects during oxygen precipitation process in lightly and heavily boron doped silicon wafers with high energy $^{11}B^+$ ion implantation. Secondary defects were inspected nearby the projected range by high resolution transmission electron microscopy. Oxygen pileup was measured in the vicinity of the projected range by secondary ion mass spectrometry for heavily boron doped silicon wafers.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.101-104
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• 2011

Many studies in crystalline silicon solar cell fabrication have been focused on high efficiency and low cost. In this paper, we carried out the doping procedure by varying the silicon wafer thicknesses and sheet resistance. The silicon wafers with various thicknesses were obtained by shiny etching and texturing. The thicknesses of wafers were 100, 120, 150, and $180{\mu}m$. The emitter layer formed by $POCl_3$ doping process had sheet resistance with 40 and $80{\Omega}/sq$ for selective emitter application. This experiment indicated wafer thickness did not influence sheet resistance but lifetime was strongly effected.

• Journal of Korea Foundry Society
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• v.33 no.4
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• pp.157-161
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• 2013

A ribbon-type polycrystalline silicon wafer was directly fabricated from liquid silicon via a novel technique for both a fast growth rate and large grain size by exploiting gas pressure. Effects of processing parameters such as moving speed of a dummy bar and the length of the solidification zone on continuous casting of the silicon wafer were investigated. Silicon melt extruded from the growth region in the case of a solidification zone with a length of 1cm due to incomplete solidification. In case of a solidification zone wieh a length of 2 cm, on the other hand, continuous casting of the wafer was impossible due to the volume expansion of silicon derived from the liquid-solid transformation in solidification zone. Consequently, the optimal length of the solidification zone was 1.5 cm for maintaining the position of the solid-liquid interface in the solidification zone. The silicon wafer could be continuously casted when the moving speed of the dummy bar was 6 cm/min, but liquid silicon extruded from the growth region without solidification when the moving speed of the dummy bar was ${\geq}$ 9 cm/min. This was due to a shift of the position of the solid-liquid interface from the solidification zone to the moving area. The present study reports experimental findings on a new direct growth system for obtaining silicon wafers with both high quality and productivity, as a candidate for an alternate route for the fabrication of ribbon-type silicon wafers.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.6
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• pp.479-485
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• 2002

We have investigated the effects of various wafers cleaning on glass/Si bonding using 4 inch Pyrex glass wafers and 4 inch silicon wafers. The various wafer cleaning methods were examined; SPM(sulfuric-peroxide mixture, $H_2SO_4:H_2O_2$ = 4 : 1, $120^{\circ}C$), RCA(company name, $NH_4OH:H_2O_2:H_2O$ = 1 : 1 : 5, $80^{\circ}C$), and combinations of those. The best room temperature bonding result was achieved when wafers were cleaned by SPM followed by RCA cleaning. The minimum increase in surface roughness measured by AFM(atomic force microscope) confirmed such results. During successive heat treatments, the bonding strength was improved with increased annealing temperatures up to $400^{\circ}C$, but debonding was observed at $450^{\circ}C$. The difference in thermal expansion coefficients between glass and Si wafer led debonding. When annealed at fixed temperatures(300 and $400^{\circ}C$), bonding strength was enhanced until 28 hours, but then decreased for further anneal. To find the cause of decrease in bonding strength in excessively long annealing time, the ion distribution at Si surface was investigated using SIMS(secondary ion mass spectrometry). tons such as sodium, which had been existed only in glass before annealing, were found at Si surface for long annealed samples. Decrease in bonding strength can be caused by the diffused sodium ions to pass the glass/si interface. Therefore, maximum bonding strength can be achieved when the cleaning procedure and the ion concentrations at interface are optimized in glass/Si wafer direct bonding.

• Journal of the Korean Society for Nondestructive Testing
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• v.37 no.1
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• pp.1-6
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• 2017

In this study, a terahertz time domain spectroscopy (THz-TDS) imaging technique was used to measure doping concentration and physical properties (such as refractive index and permittivity) of the doped silicon (Si) wafers. The transmission and reflection modes with an incidence angle of $30^{\circ}$ were employed to determine the physical properties of the doped Si wafers. The doping concentrations of the prepared Si wafers were varied from $10^{14}$ to $10^{18}$ in both N-type and P-type cases. Finally, the correlation between the doping concentration and the power of the THz wave was determined by measuring the powers of the transmitted and reflected THz waves of the doped Si wafers. Additionally, the doped thickness, the refractive index, and permittivity of each doped Si wafer were calculated using the THz time domain waveform. The results indicate that the THz-TDS imaging technique is potentially a promising technique to measure the doping concentration as well as other optical properties (such as the refractive index and permittivity) of the doped Si wafer.

• Proceedings of the Korean Society of Laser Processing Conference
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• 2002.05a
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• pp.21-24
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• 2002

• Proceedings of the Korean Vacuum Society Conference
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• 1992.02a
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• pp.97-97
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• 1992