Optimization of Differential Lock-in Detection for Five-fold Enhancement in the Spatial Resolution of a BOCDA system

2012 ◽  
Author(s):  
Ji Ho Jeong ◽  
Kwanil Lee ◽  
Kwang Yong Song ◽  
Je-Myung Jeong ◽  
Sang Bae Lee
Keyword(s):  
Spatial Resolution ◽  
Differential Lock ◽  
Lock In

Fault Localization and Functional Testing of ICs by Lock-in Thermography

2002 ◽  
Author(s):  
O. Breitenstein ◽  
J.P. Rakotoniaina ◽  
F. Altmann ◽  
J. Schulz ◽  
G. Linse
Keyword(s):  
Spatial Resolution ◽  
Electronic Device ◽  
Imaging Techniques ◽  
Heat Diffusion ◽  
Acquisition Time ◽  
Temperature Modulation ◽  
Heat Sources ◽  
Ir Camera ◽  
Free Running ◽  
Lock In

Abstract In this paper new thermographic techniques with significant improved temperature and/or spatial resolution are presented and compared with existing techniques. In infrared (IR) lock-in thermography heat sources in an electronic device are periodically activated electrically, and the surface is imaged by a free-running IR camera. By computer processing and averaging the images over a certain acquisition time, a surface temperature modulation below 100 µK can be resolved. Moreover, the effective spatial resolution is considerably improved compared to stead-state thermal imaging techniques, since the lateral heat diffusion is suppressed in this a.c. technique. However, a serious limitation is that the spatial resolution is limited to about 5 microns due to the IR wavelength range of 3 -5 µm used by the IR camera. Nevertheless, we demonstrate that lock-in thermography reliably allows the detection of defects in ICs if their power exceeds some 10 µW. The imaging can be performed also through the silicon substrate from the backside of the chip. Also the well-known fluorescent microthermal imaging (FMI) technique can be be used in lock-in mode, leading to a temperature resolution in the mK range, but a spatial resolution below 1 micron.

Cross-plane Thermoreflectance Imaging of Thermoelectric Elements

2005 ◽  
Vol 886 ◽  
Author(s):  
Peter M. Mayer ◽  
Rajeev J. Ram
Keyword(s):  
Temperature Distribution ◽  
Spatial Resolution ◽  
Quasi Equilibrium ◽  
Thermal Impedance ◽  
Thermal Measurements ◽  
Systems Identification ◽  
Lock In ◽  
Operational Device

ABSTRACTThis paper presents the first cross-plane thermoreflectance image of the temperature distribution in a thermoelectric (TE) element under bias. Using the technique of lock-in CCD thermoreflectance imaging, we can map the temperature distribution of an operational device with submicron spatial resolution and a temperature resolution of 10 mK. As such it offers a complete picture of the quasi-equilibrium transport within the device. The submicron resolution of the thermoreflectance image enables clear determination of localized heating due at interfaces - for example to due contact resistance - and thermal impedance mismatch within samples. The high spatial resolution is ideal for the characterization of thin-film thermoelectric materials where data from conventional techniques (such as the transient Harman method) are difficult to interpret. This paper also presents the first thermoreflectance data we are aware of for BiTe-based material systems. Identification and separation of the Peltier and Joule components of the heating are possible, and finite difference simulations of the devices are presented for comparison with experiment. In this way it is possible to simultaneously acquire information about the Seebeck coefficient, electrical conductivity, and thermal conductivity of the thermoelectric material. The measurements demonstrate the feasibility of non-contact thermal measurements at the sub-micron scale.

Microscale and Nanoscale Thermal Characterization Techniques

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
J. Christofferson ◽  
K. Maize ◽  
Y. Ezzahri ◽  
J. Shabani ◽  
X. Wang ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Thermal Emission ◽  
Background Radiation ◽  
Hot Spot ◽  
Single Point ◽  
Thermal Characterization ◽  
Temperature Resolution ◽  
Characterization Techniques ◽  
Resolution Limits ◽  
Lock In

Miniaturization of electronic and optoelectronic devices and circuits and increased switching speeds have exasperated localized heating problems. Steady-state and transient characterization of temperature distribution in devices and interconnects is important for performance and reliability analysis. Novel devices based on nanowires, carbon nanotubes, and single molecules have feature sizes in 1–100 nm range, and precise temperature measurement and calibration are particularly challenging. In this paper we review various microscale and nanoscale thermal characterization techniques that could be applied to active and passive devices. Solid-state microrefrigerators on a chip can provide a uniform and localized temperature profile and they are used as a test vehicle in order to compare the resolution limits of various microscale techniques. After a brief introduction to conventional microthermocouples and thermistor sensors, various contact and contactless techniques will be reviewed. Infrared microscopy is based on thermal emission and it is a convenient technique that could be used with features tens of microns in size. Resolution limits due to low emissivity and transparency of various materials and issues related to background radiation will be discussed. Liquid crystals that change color due to phase transition have been widely used for hot spot identification in integrated circuit chips. The main problems are related to calibration and aging of the material. Micro-Raman is an optical method that can be used to measure absolute temperature. Micron spatial resolution with several degrees of temperature resolution has been achieved. Thermoreflectance technique is based on the change of the sample reflection coefficient as a function of temperature. This small change in 10−4–10−5 range per degree is typically detected using lock-in technique when the temperature of the device is cycled. Use of visible and near IR wavelength allows both top surface and through the substrate measurement. Both single point measurements using a scanning laser and imaging with charge coupled device or specialized lock-in cameras have been demonstrated. For ultrafast thermal decay measurement, pump-probe technique using nanosecond or femtosecond lasers has been demonstrated. This is typically used to measure thin film thermal diffusivity and thermal interface resistance. The spatial resolution of various optical techniques can be improved with the use of tapered fibers and near field scanning microscopy. While subdiffraction limit structures have been detected, strong attenuation of the signal reduces the temperature resolution significantly. Scanning thermal microscopy, which is based on nanoscale thermocouples at the tip of atomic force microscope, has had success in ultrahigh spatial resolution thermal mapping. Issues related to thermal resistance between the tip and the sample and parasitic heat transfer paths will be discussed.

scholarly journals New Developments in IR Lock-In Thermography

2004 ◽  
Author(s):  
O. Breitenstein ◽  
J.P. Rakotoniaina ◽  
M. Hejjo Al Rifai ◽  
M. Gradhand ◽  
F. Altmann ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Spatial Resolution ◽  
Infrared Camera ◽  
Detection Sensitivity ◽  
New Developments ◽  
Technical Developments ◽  
Corrected Image ◽  
Lock In ◽  
Blurring Effect ◽  
Colloidal Bismuth

Abstract Lock-in thermography based on an infrared camera has proven to be a useful tool for failure analysis of integrated circuits (ICs). This article discusses four novel technical developments of lock-in thermography. These developments are blackening the IC surface with colloidal bismuth, the synchronous undersampling technique allowing the use of higher lock-in frequencies, displaying the 0deg/-90deg signal as a novel high resolution emissivity corrected image type, and removing the thermal blurring effect by mathematically deconvoluting the 0deg/-90deg; signal. The effect of these techniques is demonstrated by using a regularly working operational amplifier (pA 741) and a damaged capacitor as test devices. It is shown that blackening the IC surface improves the detection sensitivity in metallized regions by up to a factor of 10, whereas the other methods allow improvement of the effective spatial resolution. The article also discusses which of the spatial resolution improvement techniques is most appropriate in different situations.

Use of a Solid Immersion Lens for Thermal IR Imaging

2006 ◽  
Author(s):  
O. Breitenstein ◽  
F. Altmann ◽  
T. Riediger ◽  
D. Karg ◽  
V. Gottschalk
Keyword(s):  
Detection Limit ◽  
Spatial Resolution ◽  
Wavelength Range ◽  
Scattered Light ◽  
Operation Mode ◽  
Solid Immersion Lens ◽  
Front Side ◽  
Ir Camera ◽  
Ir Imaging ◽  
Lock In

Abstract A hemispherical silicon solid immersion lens (SIL) was used to improve the spatial resolution of front-side thermal IR imaging in lock-in mode. The bottom of the SIL was coneshaped to reduce the footprint of the SIL to the size of the imaged region. Caused by the lock-in operation mode, the detection limit improves by 2-3 orders of magnitude, and scattered light does not limit the image contrast. By using this SIL in combination with an IR camera working in the 3-5 μm wavelength range, a spatial resolution of 1.4 μm was obtained for thermal IR imaging. An automatic SIL positioning facility was constructed to place the SIL exactly in the center of the imaged region and to easily remove it after the detailed investigation.

Four-Channel Differential Lock-in Amplifiers With Autobalancing Network for Stimulated Raman Spectroscopy

2021 ◽  
pp. 1-1
Author(s):  
Giuseppe Sciortino ◽  
Andrea Ragni ◽  
Alejandro De la Cadena ◽  
Marco Sampietro ◽  
Giulio Cerullo ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Differential Lock ◽  
Lock In ◽  
Stimulated Raman

scholarly journals Ultrafast chemical imaging by widefield photothermal sensing of infrared absorption

2019 ◽  
Vol 5 (7) ◽  
pp. eaav7127 ◽  
Author(s):  
Yeran Bai ◽  
Delong Zhang ◽  
Lu Lan ◽  
Yimin Huang ◽  
Kerry Maize ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
High Throughput ◽  
Chemical Imaging ◽  
Photothermal Effect ◽  
Nanometer Scale ◽  
Light Pulses ◽  
Spectral Fidelity ◽  
Speed Up ◽  
Lock In

Infrared (IR) imaging has become a viable tool for visualizing various chemical bonds in a specimen. The performance, however, is limited in terms of spatial resolution and imaging speed. Here, instead of measuring the loss of the IR beam, we use a pulsed visible light for high-throughput, widefield sensing of the transient photothermal effect induced by absorption of single mid-IR pulses. To extract these transient signals, we built a virtual lock-in camera synchronized to the visible probe and IR light pulses with precisely controlled delays, allowing submicrosecond temporal resolution determined by the probe pulse width. Our widefield photothermal sensing microscope enabled chemical imaging at a speed up to 1250 frames/s, with high spectral fidelity, while offering submicrometer spatial resolution. With the capability of imaging living cells and nanometer-scale polymer films, widefield photothermal microscopy opens a new way for high-throughput characterization of biological and material specimens.

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