Piezo-FET Stress-Sensor Arrays for Wire-Bonding Characterization

Doelle, M.; Peters, Christian; Ruther, Patrick; Oliver, Paul

doi:10.1109/jmems.2005.863702

Cited by 47 publications

(14 citation statements)

References 24 publications

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“…The stress field under the bonding pad on a microchip can be measured during bonding only with very limited resolution [10][11][12][13] or after bonding with Raman measurements. 14) Therefore, several contributions used finite element modelling to better understand wire bonding.…”

Section: -9)mentioning

confidence: 99%

Simulation of Ultrasonic Stress During Impact Phase in Wire Bonding

Mayer¹

2013

Journal of the Microelectronics and Packaging Society

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As thermosonic ball bonding is developed for more and more advanced applications in the electronic packaging industry, the control of process stresses induced on the integrated circuits becomes more important. If Cu bonding wire is used instead of Au wire, larger ultrasonic levels are common during bonding. For advanced microchips the use of Cu based wire is risky because the ultrasonic stresses can cause chip damage. This risk needs to be managed by e.g. the use of ultrasound during the impact stage of the ball on the pad ("pre-bleed") as it can reduce the strain hardening effect, which leads to a softer deformed ball that can be bonded with less ultrasound. To find the best profiles of ultrasound during impact, a numerical model is reported for ultrasonic bonding with capillary dynamics combined with a geometrical model describing ball deformation based on volume conservation and stress balance. This leads to an efficient procedure of ball bond modelling bypassing plasticity and contact pairs. The ultrasonic force and average stress at the bond zone are extracted from the numerical experiments for a 50 µm diameter free air ball deformed by a capillary with a hole diameter of 35 µm at the tip, a chamfer diameter of 51 µm, a chamfer angle of 90 o , and a face angle of 1 o . An upper limit of the ultrasonic amplitude during impact is derived below which the ultrasonic shear stress at the interface is not higher than 120 MPa, which can be recommended for low stress bonding.

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Section: -9)mentioning

confidence: 99%

Simulation of Ultrasonic Stress During Impact Phase in Wire Bonding

Mayer¹

2013

Journal of the Microelectronics and Packaging Society

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“…Two prominent examples are packaging processes [4] and microelectronic wire bonding [5]. The knowledge of the stress distributions in these cases helps to increase the yield and thus leads to significant cost savings.…”

Section: Introductionmentioning

confidence: 99%

Novel method to operate piezo-FET-based stress sensor offers tenfold increase in sensitivity

et al. 2015

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This paper presents a novel method to operate Wheatstone bridges of piezoresistive field effect transistors (FETs) as stress sensors. Such structures consist of a square arrangement of four FETs connected by the source/drain diffusion in each corner. When the FETs are on and the bridge is operated with an input voltage between a pair of opposite contacts, the bridge output voltage appearing between the perpendicular contact pair is proportional to the difference of in-plane normal stress components. In the new method the resistivity of one of the four FETs is individually tuned by varying its gate voltage by ΔV from the common gate voltage of the other three gates, in order to rebalance the bridge. We find that the corresponding sensitivity normalized to the input voltage reaches 4.5 mV/(V MPa). It is thus a factor of about 10 higher than the conventional sensitivity based on the bridge output voltage, which reaches 490 μV/(V MPa).

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“…CMOS-based piezoresistive tactile sensors apply stress sensing elements of two types: first, implanted resistors making use of CMOS diffusions and often implemented as Wheatstone bridges; second, field effect transistors [17,18]. Both types of sensing elements exploit the piezoresistive effect in p-doped or n-doped silicon.…”

Section: Introductionmentioning

confidence: 99%

“…Their stress sensitivity is described by an expression similar to Eq. (1) where the piezoresistive coefficients π ij are replaced by Π ij [17]. Compared to piezoresistors, the main advantage of piezo-FETs is that these sensing elements comprise an inherent switch, namely the gate electrode.…”

Section: Introductionmentioning

confidence: 99%

CMOS tactile sensor systems

et al. 2013

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Tactile sensor systems based on complementary metal-oxide-semiconductor (CMOS) technologies have found a wide variety of applications covering various types of manmachine interfaces as well as industrial applications. These sensor systems are realized using commercially available CMOS processes combined with appropriate assembly technologies for advanced system packages, and dedicated micromachining processes to realize membranes or beam structures to improve the sensor sensitivity. Piezoresistive CMOS-based tactile sensor systems make use of implanted resistors and field-effect transistors (FETs) exploiting the piezoresistive effect in silicon. The applied CMOS chips extract the mechanical stress distribution in the chip surface which is characteristic for the corresponding mechanical loading of the CMOS chip or its package. This paper describes a three-dimensional force sensor used in metrology to extract the 3D geometry of precision machined parts, and the Smart Tooth, an innovative tool for orthodontic research and education.

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Piezo-FET Stress-Sensor Arrays for Wire-Bonding Characterization

Cited by 47 publications

References 24 publications

Simulation of Ultrasonic Stress During Impact Phase in Wire Bonding

Simulation of Ultrasonic Stress During Impact Phase in Wire Bonding

Novel method to operate piezo-FET-based stress sensor offers tenfold increase in sensitivity

CMOS tactile sensor systems

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