A near-infrared confocal scanner

Lee, Seung-Woo; Yoo, Hongki

doi:10.1088/0957-0233/25/6/065403

Cited by 4 publications

(11 citation statements)

References 14 publications

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“…To characterize the MCLs, AbFM has been frequently used as the method for measuring mechanical properties and testing the functions of devices under loading. This method is not appropriate for mass production, considering the requirements for low cost and fast procedure of testing [38]. The main application of AbFM is to generate the force on MCLs and mechanical parts of the sensor.…”

Section: Methodsmentioning

confidence: 99%

“…Laser-Doppler Vibrometer [33] Out of plan motion scanning laser microscope [34] abnormal vertical displacements scanning electron microscopy [35] Imaging defects computed tomography (CT) [36] Visualizing 3D structure transition electron microscopy [37] Thin-film deposited on MEMS energy-dispersive X-ray spectroscopy (EDS) [38] Chemical composition of surface wavelength X-ray spectroscopy (WDS) [39] Chemical composition of surface In retrospect, the 2000s witnessed a severe lack of universal MEMS standards for all MEMS vendors, while during this time offshoots from IC ATE providers began to emerge. In the middle of the 2000s, some regulations were established for MEMS standardization in design for standard testing.…”

Section: Destructive Non-destructivementioning

confidence: 99%

“…Computed Tomography (CT) is another solution for taking internal photos, but simplicity and high throughput is the main drawback in front of this technology [36]. Transmission Electron Microscopy (TEM), Energy-Dispersive X-ray Spectroscopy (EDS) [38], Wavelength-Dispersive X-ray Spectroscopy (WDS) [39], Infrared Microscopy [40], and Thermally Induced Voltage Alteration (TIVA) [41] are some of the methods for MEMS material testing and chemical composition evaluation that are non-destructive. These methods are also not too cheap to be used in highly parallel sensor and actuator testing, while the AbFM is a cheap solution that can be adopted to test MEMS devices at wafer-level scale.…”

Section: Destructive Non-destructivementioning

confidence: 99%

“…The last decade has witnessed an admirable surge for the introduction of diverse general characterizing and testing methods for MEMS devices, some of which are shown in Table 1 [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41]. These methods are categorized into two main groups: destructive and non-destructive testing approaches.…”

Section: Introductionmentioning

confidence: 99%

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A New Non-Invasive Air-Based Actuator for Characterizing and Testing MEMS Devices

2020

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This research explores a new ATE (Automatic Testing Equipment) method for Micro Electro Mechanical Systems (MEMS) devices. In this method, microscale aerodynamic drag force is generated on a movable part of a MEMS sensor from a micronozzle hole located a specific distance above the chip that will result in a measurable change in output. This approach has the potential to be generalized for the characterization of every MEMS device in mass production lines to test the functionality of devices rapidly and characterize important mechanical properties. The most important testing properties include the simultaneous application of controllable and non-invasive manipulative force, a single handler for multi-sensor, and non-contact characterization, which are relatively difficult to find with other contemporary approaches. Here we propose a custom-made sensing platform consisting of a microcantilever array interconnected to a data acquisition device to read the capacitive effects of each cantilever’s deflection caused by air drag force. This platform allows us to empirically prove the functionality and applicability of the proposed characterization method using airflow force stimuli. The results, stimulatingly, exhibited that air force from a hole of 5 µm radii located 25 µm above a 200 × 200 µm2 surface could be focused on a circular spot with radii of approximately 5 µm with surface sweep accuracy of <8 µm. This micro-size airflow jet can be specifically designed to apply airflow force on the MEMS movable component surface. Furthermore, it was shown that the generated air force range could be controlled from 20 nN to 60 nN, approximately, with a linear dependency on airflow ranging from 5 m/s to 20 m/s, which is from a 5 µm radius microhole air jet placed 400 µm above the chip. In this case-study chip, for a microcantilever with a length of 400 µm, the capacitance curve increased linearly from 28.2 pF to 30.5 pF with airflow variation from 5 m/s to 21 m/s from a hole. The resultant curve is representative of a standard curve for testing of the further similar die. Based on these results, this paper paves the way towards the development of a new non-contact, non-invasive, easy-to-operate, reliable, and relatively cheap air-based method for characterizing and testing MEMS sensors.

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Section: Methodsmentioning

confidence: 99%

Section: Destructive Non-destructivementioning

confidence: 99%

Section: Destructive Non-destructivementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A New Non-Invasive Air-Based Actuator for Characterizing and Testing MEMS Devices

2020

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“…To construct thermal images based on the infrared radiance emitted from the structures [67]. Nondestructive…”

Section: Infrared Microscopymentioning

confidence: 99%

A Review on Key Issues and Challenges in Devices Level MEMS Testing

et al. 2016

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The present review provides information relevant to issues and challenges in MEMS testing techniques that are implemented to analyze the microelectromechanical systems (MEMS) behavior for specific application and operating conditions. MEMS devices are more complex and extremely diverse due to the immersion of multidomains. Their failure modes are distinctive under different circumstances. Therefore, testing of these systems at device level as well as at mass production level, that is, parallel testing, is becoming very challenging as compared to the IC test, because MEMS respond to electrical, physical, chemical, and optical stimuli. Currently, test systems developed for MEMS devices have to be customized due to their nondeterministic behavior and complexity. The accurate measurement of test systems for MEMS is difficult to quantify in the production phase. The complexity of the device to be tested required maturity in the test technique which increases the cost of test development; this practice is directly imposed on the device cost. This factor causes a delay in time-to-market.

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Three-dimensional confocal reflectance microscopy for surface metrology

Kim

Yoo

2021

Meas. Sci. Technol.

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Confocal microscopy uses a confocal aperture in front of a detector to eliminate out-of-focus blur, providing optical sectioning, high spatial resolution, and high contrast. It enables precise three-dimensional (3D) reconstruction of a sample surface. Using objective lenses with high numerical aperture and short wavelength illumination, confocal microscopy offers high spatial resolution in both lateral and axial directions in a non-destructive and non-contact manner. These qualities make confocal microscopy an ideal tool for the inspection and measurement of microscopic samples. One of the limitations of confocal microscopy for 3D surface metrology, however, is its speed. Both lateral and axial scanning is needed to produce a stack of two-dimensional images along the height, and this takes more time. While high-end confocal laser scanning microscopy can acquire a 3D sample surface within a few seconds, an even faster imaging speed is required in some applications, such as in in-line inspection. Various techniques have been proposed to speed up 3D confocal measurements, such as chromatic confocal microscopy, differential confocal microscopy, dual-detection confocal microscopy, and direct-view confocal microscopy. Here, we review the basic principles, theories, scanning methods, and progress of confocal microscopy for surface metrology, and we discuss the latest progress in the field of ultrafast 3D surface measurement. We anticipate that confocal microscopy, which has become one of the standard metrology tools, will continue to evolve for 3D surface measurement.

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A near-infrared confocal scanner

Cited by 4 publications

References 14 publications

A New Non-Invasive Air-Based Actuator for Characterizing and Testing MEMS Devices

A New Non-Invasive Air-Based Actuator for Characterizing and Testing MEMS Devices

A Review on Key Issues and Challenges in Devices Level MEMS Testing

Three-dimensional confocal reflectance microscopy for surface metrology

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