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Silicon wafer etching by pulsed high-power inductively coupled Ar/CF <sub/>4</sub> plasma with 150 kHz band frequency
摘要： A silicon wafer etching using a burst pulse high-power inductively coupled plasma (ICP) is investigated. A 200 μs wide burst of a 157 kHz power supply is employed to generate ICP with a repetition rate of 50 Hz. A rectangular pulsed voltage synchronized with the burst power supply is applied upto 1 kV at the wafer. Mixed gas of argon (Ar) and tetrafluoromethane (CF4) is supplied into the vacuum chamber. The plasma density and electron temperature are 1019 m?3 and 2.8 eV where the wafer is, respectively. In the case of Ar plasma, the silicon etching rate is 0.01 μm min?1 with 1000 V negative bias. The etching rate increases to 0.23 μm min?1 by adding CF4 into Ar and increases linearly with increasing the bias voltage. The target current and emission intensity of Ar+ and F* are depended on bias voltage from ?300 to ?1000 V. The etching rate sharply increases by increasing CF4 content from 0% to 10%, and it becomes almost constant at 10%. The dependency of emission intensity of F* on CF4 content is similar to the dependency the etching rate.
关键词： Ar/CF4 plasma,high-power inductively coupled plasma,silicon wafer etching,150 kHz band frequency
更新于2025-09-23 15:21:01
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Recent advancements in micro-crack inspection of crystalline silicon wafers and solar cells
摘要： The move towards in-line instrumentation quality assurance in photovoltaic industry has triggered new interest in development of novel methods and instruments for defect detection. Among the many tests that need to be carried out on silicon wafers and solar cells during the manufacturing process is the detection of micro-cracks. To date, the optical transmission method and luminescence technologies like electroluminescence and photoluminescence are popularly used by silicon wafer and solar cell manufacturers primarily due to their practicality and speed advantages. However, the increase in production throughput speeds and the recent change in the wafer sawing process where slurry-based sawing is gradually being replaced with diamond-wire sawing presents new challenges to the industries. This short perspective presents these new challenges and highlights breakthrough inventions in response to recent development. This article concludes by identifying some research opportunities that has emerged as a result of these recent developments.
关键词： Image Processing,Micro-crack,Solar Cell,Silicon Wafer,Machine Vision
更新于2025-09-23 15:19:57
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Laser-based Thickness Control in a Double-Side Polishing System for Silicon Wafers
摘要： Thickness control is a critical process of automated polishing of large and thin Si wafers in the semiconductor industry. In this paper, an elaborate double-side polishing (DSP) system is demonstrated, which has a polishing unit with feedback control of wafer thickness based on the scan data of a laser probe. Firstly, the mechanical structure, as well as the signal transmission and control of the DSP system, are discussed, in which the thickness feedback control is emphasized. Then, the precise positioning of the laser probe is explored to obtain the continuous and valid scan data of the wafer thickness. After that, a B-spline model is applied for the characterization of the wafer thickness function to provide the thickness control system with credible thickness deviation information. Finally, experiments of wafer-thickness evaluation and control are conducted on the presented DSP system. With the advisable number of control points in B-spline fitting, the thickness variation can be effectively controlled in wafer polishing with the DSP system, according to the experimental results of curve fitting and the statistical analysis of the experimental data.
关键词： silicon wafer,B-spline fitting,double-side polishing system,laser probe,thickness control
更新于2025-09-23 15:19:57
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Numerical-experimental study on polishing of silicon wafer using magnetic abrasive finishing process
摘要： Silicon wafer as a brittle material is extensively used in semiconductors. The surface quality of this material significantly affects the quality and efficiency of related components. In this study, the coupled algorithm of SPH/FEM is used to simulate the surface polishing of silicon wafers with Magnetic Abrasive Finishing process. The effects of rotational speed and machining gap on percent change in surface roughness (%?Ra) and material removal (MR) are comprehensively analyzed with simulations and experiments. Furthermore, the material removal mechanism in wafers was investigated by using AFM. Our observations showed that both micro-fracture and micro-cutting mechanisms might happen and it highly depends on polishing parameters. Results of the simulations and experimental data showed that MR and %?Ra value increase with increasing rotational speed and decreasing machining gap. According to our experimental findings, maximum %?Ra and MR are 65% and 39.09 mg, respectively.
关键词： Material removal,Surface Roughness,Magnetic Abrasive Finishing,Al2O3,FEM/SPH,Silicon Wafer,Nano-finishing
更新于2025-09-19 17:15:36
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Surface Roughening of Silicon Wafer Solar Cell by Using ECDM Method
摘要： This research proposes surface roughening of silicon wafer solar cell by electrochemical discharge machining (ECDM). The stainless steel was used as negative electrode. The graphite was used as the positive electrode acting as the auxiliary electrode. The potassium hydroxide was used as the electrolyte. The processing parameters include the machining voltage, the processing time, the machining gap, the electrolyte concentration, the additive agent concentration, pulse frequency and duty factor, etc. The result of experiments reveals that appropriate concentrations of ethanol can expand the size of the pores and enhance surface roughening effect. The appropriate processing parameters are a machining gap of 200μm, voltage of 48V, concentration of potassium hydroxide of 3M, concentration of ethanol of 4%. The electrochemical discharge machined surface roughness was increased from 0.417μm to 0.915μm using one minute processing time. The average reflectance rate of the textured surface was decreased from 29.6% to 12.7%. This study reveals that ECDM method has the advantage of short processing time and can generate a higher surface roughness and the porous structure.
关键词： Electrical chemical discharge machining,Reflectance rate,Surface roughening,Silicon wafer solar cell
更新于2025-09-16 10:30:52
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Surface Refining by Laser Scanning on Silicon Wafers
摘要： A YAG continue-wave laser has been used to refine the surface of silicon wafers in this study. During laser scanning, the irradiated region of the surface of the wafer experienced melting and subsequent recrystallization, which results in a redistribution of metal impurities in the molten pool along the depth direction. Cross-sectional micrographs of irradiated wafers have a clear boundary, which confirms the process of recrystallization, and the depth of molten region depends on the scanning parameters and the size of wafer. Secondary ion mass spectrometry measurements have been carried out to characterize the concentration of metal impurities. After redistribution of metal impurities, a final relative purity region was formed close to the surface. SIMS measurements demonstrate that the metal impurity concentration of the purity region has significantly reduced. The mechanism of the redistribution process of metal impurities in the molten pool has been qualitatively analyzed. All of the experimental results support that the CW laser scanning technology can effectively refine the specific surfaces of silicon wafers, and this technology has a great potential in the field of solar cells.
关键词： Silicon wafer,Laser scanning,Refining,Metal impurities,Recrystallization
更新于2025-09-16 10:30:52
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Device Parameter Extraction for Loss Analysis of Silicon Solar Cells Based on Intelligent Model Fitting
摘要： A fully automated and rigorous loss analysis routine that provides a breakdown of the loss components occurring in silicon solar cells is presented in this work. The routine combines large-area two-dimensional modeling and smart auto-fitting routines with luminescence imaging. This allows the spatially resolved information in luminescence images to be analyzed to extract recombination parameters partitioned by regions (e.g. wafer edge, under metal contacts, over passivated areas), as well as the spatial distribution of contact resistance. After these cell parameters have been extracted, a loss analysis of open-circuit voltage can be performed by simulating the open-circuit condition and examining the various recombination currents, and a loss analysis of fill factor can be performed by successively turning off the effects of factors that degrade it in simulation. The technique is demonstrated on a multicrystalline silicon PERC solar cell.
关键词： Silicon wafer solar cells,model fitting,loss analysis,multivariate regression,luminescence imaging
更新于2025-09-12 10:27:22
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Light transmission and internal scattering in pulsed laser-etched partially-transparent silicon wafers
摘要： Continuing trend in silicon wafer thickness directed at cost reduction approaches basic boundaries created by: (a) mismatch between Al paste and Si wafer thermal expansion and (b) incomplete optical absorption. With its symmetrical front and back electrical contacts, the bifacial solar cell setup reduces stress due to mismatch thermal expansion, decreases metal use and increases high temperature efficiency. Efficiency improvement is accomplished in bifacial solar cells by capturing light from the back surface. Partially transparent wafers provide an option to improve near-infrared radiation absorption within Si wafer. To fully absorb optical radiation, three-dimensional texture of these kinds of wafers is essential. Pulsed laser interactions, thermal oxidation, and wet chemical etching are included in this research. A feature of its energy and pattern setup is the interaction of pulsed laser with Si, running at 1.064 μm wavelength and micro-second length. Two experimental settings were explored: (a) post-laser chemical etching with potassium hydro-oxide etching with thermal oxide as etching mask and (b) post-laser heat Si surface oxidation. Due to fast melting and recrystallization, laser pulsed processing inherently produces its own texture. Some of these spherically-shaped, randomly focused characteristics improve inner scattering and boost near-infrared absorption within the wafer. These characteristics are separated during chemical etching with the thermally-grown oxide layer as an etch mask. Comparison of optical absorption in both surfaces shows almost a rise in the magnitude of absorption in non-etched surfaces. Detailed optical (optical microscope and IR absorption), morphological (field emission scanning electron microscope) and heat imaging (far IR camera) analyses were performed to comprehend physical processes that contribute to near-IR absorption improvement. Such kinds of partially-transparent, three-dimensional textured Si wafers are anticipated to discover applications for bifacial solar cells as substrates.
关键词： Thru-holes,Optics,Silicon wafer,Materials physics,Thermal image,Partial transparent,Nanotechnology,Trench,Energy,IR transmission,Materials characterization
更新于2025-09-11 14:15:04
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Effects of HEC Concentration on Silicon Polishing
摘要： Hydroxyethyl cellulose (HEC) is believed to effectively reduce haze level in silicon final polishing. We find that the removal rate(RR) and roughness of the polishing are very sensitive to the concentration of HEC, which can be divided into two concentration ranges. Its machanism is not only absorption occurence on silicon surface but also related to HEC colloid properties. Evidence has shown that HEC covers on the surface of silica sol, and there are three forms of coverage depending on the concentration, which have different effects on the interface between silicon and abrasive during polishing. Combined with steric hindrance, a possible polishing model is discussed based on the existence of HEC which is verifed by coeffiecient of friction force(CoF) according to HEC concentration. The results not only provide guidance for effective silicon polishing, but also imply that colloidal properties of additives with surface activity should be considered in other polishing systems.
关键词： Silicon wafer,Hydroxyethyl cellulose(HEC),Chemical-mechanical polishing(CMP)
更新于2025-09-10 09:29:36
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Approaching 23% with large‐area monoPoly cells using screen‐printed and fired rear passivating contacts fabricated by inline PECVD
摘要： We present n‐type bifacial solar cells with a rear interfacial SiOx/n+:poly‐Si passivating contact (‘monoPoly’ cells) where the interfacial oxide and n+:poly‐Si layers are fabricated using an industrial inline plasma‐enhanced chemical vapor deposition (PECVD) tool. We demonstrate outstanding passivation quality with dark saturation current density (J0) values of approximately 3 fA/cm2 and implied open‐circuit voltage (iVoc) of 730 mV at 1‐sun conditions after firing in an industrial belt furnace. Using a simple solar cell process flow that can be easily adapted for mass production, a peak cell efficiency of 22.8% with a cell open circuit voltage (Voc) of 696 mV is achieved on large‐area, screen‐printed, Czochralski‐silicon (Cz‐Si) solar cells using commercial fire‐through metal pastes.
关键词： silicon wafer,screen‐printed,industrial process,passivated contacts,industrial firing,PECVD,solar cells,large‐area
更新于2025-09-04 15:30:14