An Effective Emissivity Model for Rapid Thermal Processing Using the Net-Radiation Method

A reflective shield has been placed in the lower chamber of some rapid thermal processing (RTP) systems so that the temperature of the silicon wafer can be accurately measured in situ with light-pipe radiometers. Better knowledge of the effective emissivity of the wafer reduces the uncertainty in the temperature measurement. This paper describes an enclosure model based on the net-radiation method for predicting the effective emissivity of the wafer. The model treats the surfaces in the enclosure as diffuse emitters, with a reflectivity that may include a diffuse component and a specular component. Using this model, a parametric study is performed to investigate the influence of the geometric arrangement, surface temperature and properties, and wavelength on the effective emissivity. The algorithm developed in this work may serve as a tool to improve radiometric temperature measurement in RTP systems.     

Reference-free total reflection X-ray fluorescence analysis of semiconductor surfaces with synchrotron radiation

Total reflection X-ray fluorescence (TXRF) analysis is a well-established method to monitor lowest level contamination on semiconductor surfaces. Even light elements on a wafer surface can be excited effectively when using high-flux synchrotron radiation in the soft X-ray range. To meet current industrial requirements in nondestructive semiconductor analysis, the Physikalisch-Technische Bundesanstalt (PTB) operates dedicated instrumentation for analyzing light element contamination on wafer pieces as well as on 200- and 300-mm silicon wafer surfaces. This instrumentation is also suited for grazing incidence X-ray fluorescence analysis and conventional energy-dispersive X-ray fluorescence analysis of buried and surface nanolayered structures, respectively. The most prominent features are a high-vacuum load-lock combined with an equipment front end module and a UHV irradiation chamber with an electrostatic chuck mounted on an eight-axis manipulator. Here, the entire surface of a 200- or a 300-mm wafer can be scanned by monochromatized radiation provided by the plane grating monochromator beamline for undulator radiation in the PTB laboratory at the electron storage ring BESSY II. This beamline provides high spectral purity and high photon flux in the range of 0.078-1.86 keV. In addition, absolutely calibrated photodiodes and Si(Li) detectors are used to monitor the exciting radiant power respectively the fluorescence radiation. Furthermore, the footprint of the excitation radiation at the wafer surface is well-known due to beam profile recordings by a CCD during special operation conditions at BESSY II that allow for drastically reduced electron beam currents. Thus, all the requirements of completely reference-free quantitation of TXRF analysis are fulfilled and are to be presented in the present work. The perspectives to arrange for reference-free quantitation using X-ray tube-based, table-top TXRF analysis are also addressed.     

Systematic errors in the measurement of emissivity caused by directional effects

Accurate knowledge of surface emissivity is essential for applications in remote sensing (remote temperature measurement), radiative transport, and modeling of environmental energy balances. Direct measurements of surface emissivity are difficult when there is considerable background radiation at the same wavelength as the emitted radiation. This occurs, for example, when objects at temperatures near room temperature are measured in a terrestrial environment by use ofthe infrared 8-14-microm band.This problem is usually treated by assumption of a perfectly diffuse surface or of diffuse background radiation. However, real surfaces and actual background radiation are not diffuse; therefore there will be a systematic measurement error. It is demonstrated that, in some cases, the deviations from a diffuse behavior lead to large errors in the measured emissivity. Past measurements made with simplifying assumptions should therefore be reevaluated and corrected. Recommendations are presented for improving experimental procedures in emissivity measurement.     

Research of Ultra-Black Coating Emissivity Based on a Controlling the Surrounding Radiation Method

A method of controlling the surrounding radiation, proposed to measure the emissivity of the sample with high accuracy, is introduced. Two disks at different temperatures are moved alternately in front of the sample for controlling the surrounding radiation of the sample. The emissivity of the sample is obtained from the relationship between the measured value of the radiation thermometer and the radiation from the sample. There are three samples, including the Japansensor JSC-3, Tempil Pyromark 1200, and NEXTEL Velvet Coating 811-21 ultra-black coating, measured by this method. The uncertainty contributions of this method are analyzed, and the uncertainty of the emissivity measurement method is 0.54 % (k?=?1). The surface microstructure of the coatings is measured by scanning electron microscopy, and the relationship between emissivity and the surface properties is discussed.     

Measurement of surface temperature and emissivity by a multitemperature method for Fourier-transform infrared spectrometers

Surface temperatures are estimated with high precision based on a multitemperature method for Fourier-transform spectrometers. The method is based on Planck's radiation law and a nonlinear least-squares fitting algorithm applied to two or more spectra at different sample temperatures and a single measurement at a known sample temperature, for example, at ambient temperature. The temperature of the sample surface can be measured rather easily at ambient temperature. The spectrum at ambient temperature is used to eliminate background effects from spectra as measured at other surface temperatures. The temperatures of the sample are found in a single calculation from the measured spectra independently of the response function of the instrument and the emissivity of the sample. The spectral emissivity of a sample can be measured if the instrument is calibrated against a blackbody source. Temperatures of blackbody sources are estimated with an uncertainty of 0.2-2 K. The method is demonstrated for measuring the spectral emissivity of a brass specimen and an oxidized nickel specimen.     

在中低温条件下环境辐射对光谱发射率测量的影响

讨论了有效光谱发射率和有效亮度温度的概念。介绍了光谱发射率的测量方法及测量装置。在考虑到环境辐射的情况下,给出了光谱发射率的计算方程,指出中低温条件下的光谱发射率测量必须考虑环境辐射的影响,否则会出现较大的误差。     

Effect of the observation length on the two-dimensional shadowing function of the sea surface: application on infrared 3-13-microm emissivity

An analytical approach of the two-dimensional emissivity of a rough sea surface in the infrared band is presented. The emissivity characterizes the intrinsic radiation of the sea surface. Because the temperature measured by the infrared camera depends on the emissivity, the emissivity is a relevant parameter for retrieving the sea-surface temperature from remotely sensed radiometric measurements, such as from satellites. This theory is developed from the first-order geometrical-optics approximation and is based on recent research. The typical approach assumes that the slope in the upwind direction is greater than the slope in the crosswind direction, involving the use of a one-dimensional shadowing function with the observed surface assumed to be infinite. We introduce the two-dimensional shadowing function and the surface observation length parameters that are included in the modeling of the two-dimensional emissivity.     

Gold and silica-coated gold nanoparticles as thermographic labels for DNA detection

The infrared emissivity of Au and silica-coated Au nanoparticles (Au NPs) deposited on indium tin oxide substrates was investigated. NPs were irradiated with laser light at a frequency close to the Au plasmon resonance band, and the blackbody radiation emitted as a result was monitored with an IR camera equipped with an InAs array detector. The differences in temperature before and after laser irradiation were recorded (T-jumps) and were found to be directly proportional to the number of particles present on the slide and to the laser power used in the experiment. Coating Au NPs with silica increased the measured T-jumps 2-5 times, depending on the thickness of the silica shell. This was in agreement with the observation that silica has a much higher IR emissivity than Au. Both Au and silica-coated Au NPs were then tested as labels for thermographic DNA detection. Target DNA concentrations as low as 100 pM were recorded when Au NPs were used as labels and as low as 10 pM when silica-coated Au NPs were used.     

Theoretical evaluation of a four-band fiber-optic radiometer

A theoretical simulation of a four-band fiber-optic radiometric technique is presented. This is a technique for remote, noncontact temperature measurement of a sample near room temperature, under conditions of unknown emissivity and ambient temperature. A realistic setup of a broadband IR detector, a set of three filters, an IR fiber, and a MATLAB software package for the calculations, is simulated in two steps: a calibration process and a measurement process. The results of the simulation show the limitations and advantages of the four-band radiometric technique and show the expected resolution of the sample temperature and emissivity and of the ambient temperature measurement. The theoretical resolution of the sample temperature measured by the four-band radiometric setup comes close to the resolution achieved in an equivalent single-band radiometric setup. The four-band method has an additional advantage of making it possible to calculate values of emissivity and ambient temperature.     

IR Radiometry Optical System View Factor and Its Application to Emissivity Investigations of Solid and Liquid Phases

An optical system for fast IR radiometry designed for investigations of thin film thermal properties and pulsed laser melting was analyzed in this work. A methodology for determination of the view factor from calibration measurements was developed. The view factor (0.0255) of the optical system containing two paraboloid mirrors was determined experimentally from calibration measurements on pure metals and metallic alloys. The knowledge of the view factor was then applied to normal emissivity investigations at IR wavelengths. The emissivity of tungsten films prepared by magnetron sputtering was determined for different deposition conditions, varying between 0.036 and 0.071. Liquid phase emissivities of Cu, Mo, Ni, Si, Sn, Ti, and steel were also determined and were found to be higher than solid-state emissivities as predicted from the literature. A knowledge of the liquid-state emissivity of silicon enabled recalculation of the IR signal evolution to the temperature evolution, during and after a nanosecond laser pulse. This was not possible by use of the usual calibration because of silicon’s semi-transparent behavior in the IR range (1–10 μm) in the solid-state phase.     

Handheld Reflective Foil Emissometer with 0.007 Absolute Accuracy at 0.05

The development and performance of a handheld emissometer for the measurement of the emissivity of highly reflective metallic foils used for the insulation of domestic and commercial buildings are described. Reflective roofing insulation based on a thin coating of metal on a more robust substrate is very widely used in hotter climates to reduce the radiant heat transfer between the ceiling and roof in commercial and residential buildings. The required normal emissivity of these foils is generally below 0.05, so stray reflected ambient infrared radiation (IR) makes traditional reflectance-based measurements of emissivity very difficult to achieve with the required accuracy. Many manufacturers apply additional coatings onto the metallic foil to reduce visible glare during installation on a roof, and to provide protection to the thin reflective layer; however, this layer can also substantially increase the IR emissivity. The system as developed at the National Measurement Institute, Australia (NMIA) is based on the principle of measurement of the modulation in thermal infrared radiation, as the sample is thermally modulated by hot and cold air streams. A commercial infrared \(8\,\upmu \hbox {m}\) to \(14\,\upmu \hbox {m}\) band radiation thermometer with a highly specialized stray and reflected radiation shroud attachment is used as the detector system, allowing for convenient handheld field measurements. The performance and accuracy of the system have been compared with NMIA’s reference emissometer systems for a number of typical material samples, demonstrating its capability to measure the absolute thermal emissivity of these very highly reflective foils with an uncertainty of better than \(0.007, k = 2.07, 95\,\%\) .     

Asymmetrical Emissivity and Wettability in Stitching Treble Weave Metafabric for Synchronous Personal Thermal-Moisture Management

Developing textiles with passive thermal management is an effective strategy to maintain the human body healthy as well as decrease energy consumption. Personal thermal management (PTM) textiles with engineered constituent element and fabric structure have been developed, however the comfortability and robustness of these textiles remains a challenge due to the complexity of passive thermal-moisture management. Here a metafabric with asymmetrical stitching treble weave based on woven structure design and yarn functionalization is developed, in which the thermal radiation regulation and moisture-wicking can be achieved simultaneously throughout the dual-mode metafabric due to its optically regulated property, multi-branched through-porous structure and surface wetting difference. With simply flipping, the metafabric enables high solar reflectivity (87.6%) and IR emissivity (94%) in the cooling mode, and a low IR emissivity of 41.3% in the heating mode. When overheating and sweating, the cooling capacity reaches to ≈9 °C owing to the synergistic effect of radiation and evaporation. Moreover, the tensile strengths of the metafabric are 46.18 MPa (warp direction) and 37.59 MPa (weft direction), respectively. This work provides a facile strategy to fabricate multi-functional integrated metafabrics with much flexibility and thus has great potential for thermal management applications and sustainable energy.     

Estimation of emission properties for silica particles using thermal radiation spectroscopy

This paper shows that spectrally resolved thermal radiation from silica aggregate particles can be used to extract an emissivity and a temperature in the visible regime. Emissivity of silica aggregate particles at temperatures above 2000?K is measured by the analysis of emission radiation spectra from the particles. Temperature is estimated from the relation between the emission intensity and the wavenumber. Relative emissivities at temperatures from 2150 to 2919?K are presented. Proper knowledge of optical properties for silica aggregate particles will help further the understanding of thermophysics at high temperature.     

Influence of Non-ideal Blackbody Radiator Emissivity and a Method for its Correction

Demands for accurate temperature measurement and calibration are increasing along with the wider use of radiation thermometry in industry. However, the deviation of a ‘blackbody’ radiator emissivity from the emissivity of an ideal blackbody remains one of the main uncertainty contributions in the calibration of radiation thermometers, although the performance of blackbody radiators has been continually improving. Nevertheless, the influence of this deviation was often ignored due to the complexity of the correction. In this paper, general methods to evaluate the influence of the emissivity deviation of a blackbody radiator from unity for typical radiation thermometer models are described. An approximate practical method for wide-band radiation thermometers is proposed. Moreover, the concept of equivalent wavelength and the corresponding calculation method are introduced to simplify the mathematical model. The calculation result and a mathematical expression for the equivalent wavelength applicable to most popular radiation thermometers with a spectral range of 8–14 μm are given. The analysis and calculation show that the influence of blackbody radiator emissivity on longer working-wavelength radiation thermometer calibrations at mid or high temperatures cannot be ignored.     

A Summary of Lightpipe Radiation Thermometry Research at NIST

During the last 10 years, research in light-pipe radiation thermometry has significantly reduced the uncertainties for temperature measurements in semiconductor processing. The National Institute of Standards and Technology (NIST) has improved the calibration of lightpipe radiation thermometers (LPRTs), the characterization procedures for LPRTs, the in situ calibration of LPRTs using thin-film thermocouple (TFTC) test wafers, and the application of model-based corrections to improve LPRT spectral radiance temperatures. Collaboration with industry on implementing techniques and ideas established at NIST has led to improvements in temperature measurements in semiconductor processing. LPRTs have been successfully calibrated at NIST for rapid thermal processing (RTP) applications using a sodium heat-pipe blackbody between 700 °C and 900 °C with an uncertainty of about 0.3 °C (k = 1) traceable to the International Temperature Scale of 1990. Employing appropriate effective emissivity models, LPRTs have been used to determine the wafer temperature in the NIST RTP Test Bed with an uncertainty of 3.5 °C. Using a TFTC wafer for calibration, the LPRT can measure the wafer temperature in the NIST RTP Test Bed with an uncertainty of 2.3 °C. Collaborations with industry in characterizing and calibrating LPRTs will be summarized, and future directions for LPRT research will be discussed.     

All-fiber-optic infrared multispectral radiometer for measurements of temperature and emissivity of graybodies at near-room temperature

An all-fiber-optic infrared multispectral radiometer for measurements of temperature and emissivity of graybodies at near-room temperature was constructed. Different spectral regions in the radiometer were obtained by use of hollow glass waveguides (HGWs) as filters. Using HGWs instead of bulk filters was advantageous because each HGW can be used as two different spectral filters when a dual-band IR detector is used. In addition, HGWs are much cheaper than the bulk IR filters that are usually used in such applications. For one graybody with a mean emissivity of 0.71, the estimated mean errors obtained for sample temperature, ambient temperature, and sample emissivity for all measured temperatures were 0.50% (approximately 1.65 K), 0.48% (approximately 1.4 K), and 7.3% (approximately 0.052) respectively. For a second graybody with a mean emissivity of 0.8 the estimated mean errors were 0.35% (approximately 1.2 K), 0.48% (approximately 1.4 K), and 5.0% (approximately 0.04), respectively.     

Linearity Study of a Spectral Emissivity Measurement Facility

Linearity is one of the important characteristics of a spectral radiation measurement facility. Basically, it depends on the linearity of the spectral responsivity of the detector and amplifier at different wavelengths. As spectral emissivity is measured over wide wavelength and temperature ranges and the detection system has significant drift and noise, it is not easy to measure the linearity of this facility accurately using only one standard radiator. A simple double-blackbody method has been adopted to simulate reference emissivity samples and test the linearity of the spectral emissivity measurement facility developed at the National Institute of Metrology. Good linearity results were obtained from 3 μm to 15 μm. This method minimizes the influence of drift on the emissivity measurement over a wide ratio of measurement signals and wide spectral range.     

Shift scheduling for steppers in the semiconductor wafer fabrication process

In this paper, an approach is proposed for scheduling stepper machines that are acting as bottleneck machines in the semiconductor wafer fabrication process. We consider the problem of scheduling the steppers for an 8 hour shift, determining which types of wafer lots to work on each machine. The scheduling objective is to find the optimal stepper allocations such that the schedule meets target production quantities that have been derived from the given target Work-In-Process (WIP) levels. A Mixed Integer Programming (MIP) model is formulated, and three heuristic approaches are proposed and tested to approximately solve the M1P model. Numerical tests show that one of the proposed heuristics using linear programming relaxation of MIP generates, on average, schedules within 5° of the optimum values.     

排布特征对碳素纤维红外发射率性能的影响

利用自动分光辐射测量仪系统测试了3种典型碳素纤维预制体样品的法向光谱发射率和法向总发射率,研究了排布特征对碳素纤维红外发射率性能的影响。结果表明,股线型和短切毡型碳素纤维预制体的法向光谱发射率在整个测试波段内均大于编织布状样品,股线型和短切毡型碳素纤维预制体的法向总发射率分别为0.910和0.888,均高于编织布样品。根据SEM微观形貌测试及物体表面的电磁理论分析,松散的纤维排布结构有利于碳素纤维预制体红外发射率的提高。     

Measurement of Temperature Increment in Compressive Quasi-Static and Dynamic Tests Using Infrared Thermography

Abstract:  During the plastic deformation of metals, part of the mechanical energy is retained in the material as plastic deformations and the rest is converted to heat. A temperature increment is a measure of the heat energy generated in the tested specimen. This temperature can be detected by measuring the infrared (IR) radiation emitted by the specimen surface. This study describes an attempt to improve the experimental procedure using IR thermography to measure the temperature increment as a function of the plastic strain of the studied materials. Tests were carried out under quasi-static and dynamic load conditions (using a universal testing machine and a Split Hopkinson pressure bar). The method is applied on an Al alloy (Al6082), a Mg alloy (ZC71) and the same Mg alloy reinforced with ceramic particles (SiC, 12 vol%). The emissivity measurement of the studied materials is detailed, as well as the method of synchronising the IR camera with the testing machines. Finally, the influence of test conditions on the measured temperature is analysed.