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Thermal characterization of nano-featured devices is a critical challenge for the development of high performance devices. Although far-field thermoreflectance imaging is limited in spatial resolution by the optical diffraction limit, it is more amenable to absolute temperature calibration of plasmonic devices than existing near-field scanning probe tip methods. We have built an advanced thermoreflectance...
This paper presents a novel method for obtaining optimized, accurate, and fully calibrated images of the thermal behavior of complex semiconductor devices with submicron features. To thermally analyze the growing number of high power devices, such as microwave amplifiers for wireless mobile applications, a technique is required for high speed transient and high spatial resolution thermal characterization...
Transient thermal characterization by thermal imaging in our earlier work demonstrated its ability to extract key information about the thermal response of transistors under operating conditions. We investigate a non-equilibrium response to a short time pulse for very high frequency devices, e.g. hetero-junction bipolar transistors (HBTs). Characterizing high speed thermal signals from devices with...
Shrinking features and growing device complexity with today's advanced devices has led to increased challenges of gaining a full understanding of device thermal behavior. At the same time, with higher power densities having a full understanding of the device static and dynamic thermal behavior is essential for ensuring optimal tradeoffs between performance and device reliability. Thermal imaging based...
Shrinking features and growing device complexity with today's advanced devices has led to increased challenges of gaining a full understanding of device thermal behavior. At the same time, with higher power densities having a full understanding of the device static and dynamic thermal behavior is essential for ensuring optimal tradeoffs between performance and device reliability. Thermal imaging based...
To achieve the required performance with high speed switching transistors, the gate feature length in communication devices is as small as a few tens of nanometers in multi finger configurations and transistors are arrayed in a Monolithic Microwave Integrated Circuit (MMIC). The technology therefore, makes thermal characterization more and more difficult. We employ a transient thermal imaging technique...
Transient thermal response provides rich information about the thermal behavior of advanced transistors and devices. We present the transient thermal modeling and analysis based on an instantaneous thermal imaging technology with transistor level spatial resolution for a high power GaN HEMT. The time responses show the clear separations of sources in temperature rises. At the transistor level or die...
Thermoreflectance thermal imaging microscopy is based on very small change in the surface reflection as a function of temperature. Image shift and instrument drift are limiting factors to obtain accurate and reproducible thermal images. Under large magnification and for devices with sizes on the order of hundreds of nanometers, image registration could significantly encumber accurate thermoreflectance...
Thermoreflectance imaging provides sub-micron spatial resolution with transient capability for thermal imaging of advanced semiconductor devices. Today's RF transistors and microwave devices, however, have presented significant optical challenges. This paper describes the equipment for achieving sub-micron resolution and includes thermal imaging examples for GaN HEMT devices and MMICs, followed by...
Discrete high power RF varactors based on bariumstrontium-titanate are presented in this paper. They are targeting high power applications up to 3 GHz and feature power handling capabilities up to 50 W as well as promising tunability, due to the novel metal-insulator-metal configuration. The varactors are fabricated on Al2O3 in screen-print thick-film technology and mounted in RF-power transistor...
Decreased feature sizes with today's advanced microwave devices has led to increased functionality and decreasing chip sizes. Not only higher power density but also localized hotspots have become a significant concern for transistor performance and long term reliability. Arrhenius's law in chemical reaction dominates the reliability of highly doped semiconductors designed for higher switching speeds...
We present the high resolution thermal characterization of a GaAs MMIC. The thermal imaging technique provides sub-microsecond temporal and sub-micron spatial resolutions. The results show that the gate area heats up in less than 3 us, much faster than the other area of the transistor. Also, the thermal cross talk between transistor arrays takes place in 100s us. This imaging method revealed unique...
We present the thermoreflectance thermal imaging method and the equipment for transient thermal characterization with a time resolution of 100 ns and a sub-micron spatial resolution for high speed RF and communication devices. Thermoreflectance is a non-invasive and non-contact imaging method. Our unique approach interlocks the timing of image acquisition and the device biasing such that a high speed...
Akin to any experimental system, thermoreflectance thermal imaging is not immune to different sources of noise. Although averaging the thermal images over long times can minimize the impact of the noise on the measurement, electrical, thermal and optical noises can still exist that can, subsequently, affect the accuracy of the temperature measurement. The goal of this work is to systematically look...
Thermal characterization of high-speed switching power transistors, such as high electron mobility transistors (HEMT), is critical for the evaluation of their performance as well as their long-term reliability. Unlike IR thermal imaging, thermoreflectance thermal imaging (TRI) uses LED lights in the visible range and therefore can be used to measure thermal response of these nanoscale devices under...
Self-heating in gallium nitride based high frequency, high electron mobility power transistors (GaN HEMTs) is inspected using micro-Raman thermography and 800 picosecond transient thermoreflectance imaging. The two methods provide complementary temperature information inside the semiconductor and on top metal layers of the GaN HEMT. Self heating is measured under both steady-state and ultra-fast pulsed...
Precise temperature knowledge is a key parameter to estimate the performances and predict the reliability of semiconductor devices. As a direct temperature measurement within a channel is most of the time not achievable, a common approach is to measure the device surface temperature and then to use simulations to estimate the channel temperature. In this paper, we propose to evaluate the interests...
Hetero junction Bipolar Transistor (HBT) and High Electron Mobility Transistor (HEMT) arrays are commonly used for RF and microwave high speed and high power applications. Thermoreflectance imaging can be utilized to understand the transient thermal characteristics of a GaN HEMT device. A time resolution of 50 ns clearly shows the thermal location-dependent time constants for the device, which could...
Packaging of optoelectronic devices becomes more and more challenging due to higher heat generation per unit volume. We experimentally investigated the packaging thermal resistance for a semiconductor laser device and compared results for two material alternatives for the electrical passivation layer. We used the time-resolved thermoreflectance technique to obtain the time response for the thermal...
Electrostatic discharge (ESD) protection devices are critical in preventing static charge from damaging integrated circuit (IC) chips. Due to the high speed nature of the ESD event, however, thermal characteristics have been hard to capture or characterize. We investigated the use of the transient thermoreflectance imaging method to characterize the temperature distribution in a time series of thermal...
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