Parasitic Probe Effects in Measurements of Coplanar Waveguides with Narrow Ground Width

Phung, Gia Ngoc; Arz, Uwe

doi:10.1109/spi48784.2020.9218166

Cited by 9 publications

(7 citation statements)

References 10 publications

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“…The total width was chosen to avoid the additional 379 radiation effects at high frequencies [22]. The signal and gap 380 sizes were chosen based on the manufacturing constraints, 381 while respecting the conclusions made in [4], i.e., W gnd ≥ 382 2W gap + W sig . Finally, the pads and tapers were designed to 383 permit the use of various 50-μm pitch probes on such narrow 384 coplanar structures.…”

Section: Calibration Substrate 374mentioning

confidence: 99%

“…Since most calibration algorithms suppose that only one or two modes propagate in the transmission lines, the unshielded environment of on-wafer measurements makes such calibration sensitive to many more uncertainty sources. These include additional unexpected propagating modes [3] and evanescent modes around the probe transition [4]. In addition, any change in the probe behavior between calibration standards and device under test (DUT) will also degrade the measurement accuracy.…”

mentioning

confidence: 99%

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Compensating Probe Misplacements in On-Wafer S-Parameters Measurements

Schmidt

Clochiatti

Mutlu

et al. 2022

IEEE Trans. Microwave Theory Techn.

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As the maximum frequency of electronics is rising, 1 on-wafer measurements play an important role in modeling 2 of integrated devices. Most of the time, due to the lack of 3 measurement accuracy beyond 110 GHz, such models are usually 4 extracted at frequencies much below their working frequencies 5 and are subsequently extrapolated. The validity of such models is 6 then mostly verified after fabrication of the complete chip, with a 7 simple pass and fail test. This is stating the necessity of enhancing 8 measurement results by any means possible, i.e., to reduce the 9 overall uncertainty in such measurements. It is widely accepted 10 that one of the main sources of uncertainty in such measurements 11 is probe contact repeatability, since it is difficult to reach 12 position accuracy below a few micrometers. We are presenting 13 in this article a method to model the S-parameter variation with 14 probe position on the pads, which can then be used to either 15 estimate contact repeatability uncertainty or further enhance 16 measurement results. The approach is validated based on the 17 measurements performed at 500 GHz. 18 Index Terms-Calibration, on-wafer measurements, probe 19 contact repeatability. 20 I. INTRODUCTION 21 O N-WAFER S-parameters' measurements have the advan-22 tage to characterize on-chip devices without the need 23 for complex waveguide packaging in mm and submm-wave 24 frequencies. In addition, it is a key method for modeling such 25 integrated components, allowing for a much closer evaluation 26 of the manufacturing process, thus improving the overall 27 performance of integrated circuits at these frequencies. The 28 main reason is that the calibration plane is defined directly 29 in the substrate transmission lines. Therefore, it is much 30 closer to the integrated components, without the need to use 31 approximate connector deembedding methods.

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Section: Calibration Substrate 374mentioning

confidence: 99%

mentioning

confidence: 99%

Compensating Probe Misplacements in On-Wafer S-Parameters Measurements

Schmidt

Clochiatti

Mutlu

et al. 2022

IEEE Trans. Microwave Theory Techn.

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“…One of these challenges is an understanding of the link between the positioning of such probes and their inherent mechanical flexibility. This is particularly important in terms of the impact of positional errors on optimum electrical contact [6]; something that has been studied in rigid commercial probes [7][8][9][10][11][12][13][14]. In contrast, the micromechanical behaviour (bending and twisting) of miniature microcantilever-based probes must be taken into account for optimum probe contacting [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Tilt-related alignment issues in miniature micromechanical on-wafer electrical probes composed of multiple flexible microcantilevers

Arscott

2024

Eng. Res. Express

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Some new issues concerning the contacting and positioning of small electrical microelectromechanical systems (MEMS) probes based on multiple, flexible microcantilevers are presented here. A tilt error, associated with the lateral probe roll, means that contact touchdown occurs sequentially in different cantilevers upon increasing probe overtravel. To understand the relationship between probe overtravel, tip skate, tip planarity, tip tangency, and contact force in the different contacts, the relationship between mechanical bending and torsion of the flexible cantilevers needs to be accounted for. The study reveals the conditions for achieving contact planarity and desired contact force, as well as the identification of a new ‘differential skate error’ contact misalignment associated with such MEMS probes based on multiple, flexible microcantilevers. This misalignment leads to a ‘differential contact force error’ which has implications for electrical contact quality. An experimental scale model probe based on three cantilevers is used to test the modelling—the results agree well with the predictions of the model. Interestingly, the experiments revealed an effect not accounted for in the modelling; this ‘twist error’ resulted in the cantilever lead edge not being parallel to the touchdown plane. The findings may be useful for engineers involved with the automatic control positioning of such emerging miniature probes, especially in terms of the impact of probe positioning errors.

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“…In 2019 Zhang et al [46] demonstrated the first differential on-wafer probe with integrated balun operating in the 220-330 GHz band. It has very recently been pointed out that GSG probes can have a number of side effects during measurements [47,48].…”

Section: Introductionmentioning

confidence: 99%

A comparison of pad metallization in miniaturized microfabricated silicon microcantilever-based wafer probes for low contact force low skate on-wafer measurements

Daffe¹,

Marzouk²,

Boyaval³

et al. 2021

J. Micromech. Microeng.

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Miniaturized, microfabricated microelectromechanical systems (MEMS)-based wafer probes are used here to evaluate different contact pad metallization at low tip forces (<mN) and low skate on the on-wafer pads. The target application is low force RF probes for on-wafer measurements which cause minimal damage to both probes and pads. Low force enables the use of softer, more conductive metallisation. We have studied four different thin film contact pad metals based on their thin film electrical resistivity and micro-hardness: gold, nickel, molybdenum, and chromium. The contact pads sizes were micrometre (1.9×1.9 µm2) and sub-micrometre (0.6×0.6 µm2). The contact resistance of Au-Au, Ni-Au, Mo-Au, and Cr-Au was measured as a function of tip deflection. The tip force (loading) of the contacts was evaluated from the deflection of the cantilever. It was observed that an overtravel of 300 nm resulting in a contact force of ~400 µN was sufficient to achieve a contact resistance <1 Ω for a sub-micrometre gold contact pad. Our results are compared with an analytical model of contact resistance in loaded metal-metal contacts—a reasonable fit was found. A larger contact resistance was observed for the other metals—but their hardness may be advantageous when probing other materials. Using a combination of a rigid silicon cantilever (>1000 Nm-1) and small contact pads enabled us to show that it is the length of the pad (in contact with the surface) which determines the contact resistivity rather than the total contact pad area.

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Parasitic Probe Effects in Measurements of Coplanar Waveguides with Narrow Ground Width

Cited by 9 publications

References 10 publications

Compensating Probe Misplacements in On-Wafer S-Parameters Measurements

Compensating Probe Misplacements in On-Wafer S-Parameters Measurements

Tilt-related alignment issues in miniature micromechanical on-wafer electrical probes composed of multiple flexible microcantilevers

A comparison of pad metallization in miniaturized microfabricated silicon microcantilever-based wafer probes for low contact force low skate on-wafer measurements

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