Improved thermal management of low voltage power devices with optimized bond wire positions

Köck, Helmut; Djelassi, Christian; Filippis, Stefano de; Illing, Robert; Nelhiebel, Michael; Ladurner, Markus; Glavanovics, Michael; Pogány, D.

doi:10.1016/j.microrel.2011.06.052

Cited by 8 publications

(4 citation statements)

References 11 publications

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“…The thermomechanical stress, induced by the temperature cycles, weakens this interface and can lead to catastrophic events, such as bond wire lift off. Several studies focus on the bond wire failure mechanisms [2,4,[12][13][14]. Bond wire heel crack failures [15] observed by experiments are found to be strongly dependent on the geometry and the thermal management of power devices.…”

Section: Introductionmentioning

confidence: 99%

Aluminum metallization and wire bonding aging in power MOSFET modules

Ruffilli

Berkani

Dupuy³

et al. 2018

Materials Today: Proceedings

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A limiting factor for the long-term reliability of power MOSFET-based devices is the electro-thermal and/or thermo-mechanical aging of the metallic parts. In this paper we assess the bonding wire and source metallization degradation of power devices, designed for applications in the automotive industry. Our approach consists in characterizing the metal microstructure before and after accelerated aging tests, by scanning electron microscopy, ion milling and microscopy, focused ion beam tomography, transmission electron microscopy and grain structure mapping. To focus on the wire-metallization bonding interface, we have set up a dedicated sample preparation that allows us to disclose the metallization under the bonding wires. This critical location is significantly different from the naked metallization, as the bonding process induces plastic deformation prior to aging. The main mechanism behind the device failure is the generation and propagation of fatigue cracks in the aluminum metallization. Away and under the wire bonds, they run perpendicularly from the surface down to the silicon substrate following the grain boundaries, due to an enhanced self-diffusion of aluminum atoms. Moreover, initial imperfections in the wire-metallization bonding (small cavities and aluminum oxide residues) are the starting point for harmful cracks that propagate along the wire-metallization interface and can eventually cause the wire lift-off. These phenomena can explain the local increase in the device resistance occurring at failure.

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Section: Introductionmentioning

confidence: 99%

Aluminum metallization and wire bonding aging in power MOSFET modules

Ruffilli

Berkani

Dupuy³

et al. 2018

Materials Today: Proceedings

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“…A calibration process is required to correlate the target temperature to the corresponding IR camera raw data. Thus, focus images and a pixel-by-pixel overlap in the image sequence are required [1].…”

Section: Introductionmentioning

confidence: 99%

“…In microscopy, focusing is an important but also a critical step because the focus position has to be adjusted when the microscopic target system starts moving in the optical axis. A system stays in focus if the distance between the focal plane and the camera (d f ) and the distance between the camera and the image plane (d i ) satisfy equation (1), where f is the focal length of the lens [2,3]. If the system is in focus, the image is clear; otherwise, it appears blurred by subjective visual inspection.…”

Section: Introductionmentioning

confidence: 99%

Auto focus and image registration techniques for infrared imaging of microelectronic devices

Florian¹,

Köck²,

Plankensteiner³

et al. 2013

Meas. Sci. Technol.

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An infrared (IR) microscope camera system is used to measure the temperature distribution of power devices during electrical stress pulses. A calibration is required to correlate the target temperature to the corresponding raw data of the IR camera. The IR microscope camera system contains a fixed lens; this means that the whole camera has to be moved to detect focus images. During the heating up or cooling down process, the thermo-mechanical expansion influences the measurement results. For the calibration of the power device, focus images and a pixel-by-pixel registration of individual images are required. In this paper, methods are discussed to prepare the images for the calibration process. The issues concerning finding the focus image and guaranteeing a pixel-by-pixel overlap in the image sequence are solved and evaluated by the proposed auto focus and the image correlation algorithms. An IR camera equipped with a fixed focus lens is used to perform the measurements; hence, no geometrical distortion occurs. To detect the focus position and corresponding focus image, the principle of passive focusing is used, where a focus curve is recorded. Different methods are discussed to compute the focus value. Image registration is applied to compute the distortion between the images and guarantee a pixel-by-pixel overlap. In our case, the most significant parameter is the displacement; hence, the SIFT algorithm of Lowe and a simple image correlation algorithm are implemented and compared.

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“…Khemka et al [9] propose the redistribution of the power dissipation density by decreasing the metal-oxide-semiconductor field-effect transistor (MOSFET) channel length and the thickness of the gate oxide in the outer device areas. Köck et al [10] suggest optimized bond wire positions to increase energy capability.…”

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confidence: 99%

An Easily Implementable Approach to Increase the Energy Capability of DMOS Transistors

Zawischka

Pfost

Costachescu

2014

IEEE Trans. Electron Devices

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DMOS transistors are often subject to high power dissipation and thus substantial self-heating. This limits their safe operating area because very high device temperatures can lead to thermal runaway and subsequent destruction. Because the peak temperature usually occurs only in a small region in the device, it is possible to redistribute part of the dissipated power from the hot region to the cooler device areas. In this way, the peak temperature is reduced, whereas the total power dissipation is still the same. Assuming that a certain temperature must not be exceeded for safe operation, the improved device is now capable of withstanding higher amounts of energy with an unchanged device area. This paper presents two simple methods to redistribute the power dissipation density and thus lower the peak device temperature. The presented methods only require layout changes. They can easily be applied to modern power technologies without the need of process modifications. Both methods are implemented in test structures and investigated by simulations and measurements.Index Terms-DMOS transistor, integrated power technologies, peak temperature, power dissipation density, power metaloxide-semiconductor field-effect transistor (MOSFET), thermal behavior, thermal runaway.

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Improved thermal management of low voltage power devices with optimized bond wire positions

Cited by 8 publications

References 11 publications

Aluminum metallization and wire bonding aging in power MOSFET modules

Aluminum metallization and wire bonding aging in power MOSFET modules

Auto focus and image registration techniques for infrared imaging of microelectronic devices

An Easily Implementable Approach to Increase the Energy Capability of DMOS Transistors

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