Kin Cheung - Academia.edu (original) (raw)

Papers by Kin Cheung

Advanced Functional Materials, Jan 15, 2018

We report on a novel semiconductor reliability technique that merges electrically detected magnet... more We report on a novel semiconductor reliability technique that merges electrically detected magnetic resonance (EDMR) with a conventional semiconductor wafer probing station. This union with a semiconductor probing station allows EDMR measurements to be performed at the wafer level. Our measurements forgo a microwave cavity or resonator for a very small non-resonant near field microwave probe [1]. Bipolar amplification effect (BAE) [4] and spin dependent charge pumping (SDCP) [5] were demonstrated on various SiC MOSFET structures. These measurements were made via frequency-swept EDMR. The elimination of the resonance cavity, and incorporation with a wafer probing station, greatly simplifies the EDMR detection scheme and offers promise for widespread EDMR adoption in semiconductor reliability laboratories.

IEEE Electron Device Letters, 1995

Serious n-channel transistor hot-carrier life-time degradation due to plasma-charging damage duri... more Serious n-channel transistor hot-carrier life-time degradation due to plasma-charging damage during PETEOS deposition is reported for the first time. Contrary to conventional wisdom, a dielectric film thickness dependent damage is observed. A new mechanism for charging-damage during plasma deposition of dielectric is proposed. This new mechanism uses photoconduction to explain why the antennae continue to charge up after a layer of dielectric is deposited on top. Some numerical estimation is provided.

International Integrated Reliability Workshop, Feb 1, 2018

IEEE Electron Device Letters, 2011

Geometric magnetoresistance (gMR) provides a promising solution to the difficult challenges assoc... more Geometric magnetoresistance (gMR) provides a promising solution to the difficult challenges associated with channel mobility extraction in nanoscale transistors. However, this technique requires significant experimental considerations which are uncommon in most laboratories. In addition, removing the influence of series resistance on the extracted mobility introduces further difficulty. In this letter, we present a new gMR measurement methodology that not only greatly simplifies the experimental requirements but also yields mobility values which are free from series resistance effects.

2018 IEEE International Electron Devices Meeting (IEDM), 2018

We report multi-level MoTe 2-based resistive random-access memory (RRAM) devices with switching s... more We report multi-level MoTe 2-based resistive random-access memory (RRAM) devices with switching speeds of less than 5 ns due to an electric-field induced 2H to 2H d phase transition. Different from conventional RRAM devices based on ionic migration, the MoTe 2-based RRAMs offer intrinsically better reliability and control. In comparison to phase change memory (PCM)-based devices that operate based on a change between an amorphous and a crystalline structure, our MoTe 2-based RRAM devices allow faster switching due to a transition between two crystalline states. Moreover, utilization of atomically thin 2D materials allows for aggressive scaling and high-performance flexible electronics applications. Multi-level stable states and synaptic devices were realized in this work, and operation of the devices in their low-resistive, high-resistive and intrinsic states was quantitatively described by a novel model.

2010 IEEE International Reliability Physics Symposium, 2010

A popular defect depth-profiling technique, frequency-dependent charge-pumping is carefully reexa... more A popular defect depth-profiling technique, frequency-dependent charge-pumping is carefully reexamined. Without complicated math of modeling, the physics behind the technique is examined clearly. It is shown that there is no unique relationship between the measurement frequency and the probed depth. The conclusion is that frequency-dependent chargepumping is not a defect depth-profiling technique. Keywords-frequency dependent charge pumping I.

2014 12th IEEE International Conference on Solid-State and Integrated Circuit Technology (ICSICT), 2014

2013 IEEE International Integrated Reliability Workshop Final Report, 2013

Fast-CV measurements are frequently being used to study transient phenomena associated with advan... more Fast-CV measurements are frequently being used to study transient phenomena associated with advanced devices. In this study, we show that many artifacts plague this measurement and then provide a proper method to legitimize fast-CV measurements as trustworthy. We show a remarkably accurate correspondence between a complete fast CV measurement, from accumulation to inversion, and a conventional CV measurement on the same device. The results distinguish fast-CV as a powerful tool for device characterization and reliability measurements.

IEEE Electron Device Letters, 2014

Charge pumping is one of the most relied techniques used to quantify interface defects in metal-o... more Charge pumping is one of the most relied techniques used to quantify interface defects in metal-oxide-semiconductor devices. However, conventional charge pumping is easily hindered by excessive gate leakage currents, which render the technique unsuitable for advanced technology nodes. We demonstrate a new frequency-modulated charge pumping methodology in which we transform the quasi-dc charge pumping measurement into an ac measurement. The ac detection scheme is highly resistant to gate leakage currents and extends the usefulness of charge pumping as a defect monitoring tool for future technologies.

2009 IEEE International Conference on IC Design and Technology, 2009

We utilize low-frequency noise measurements to examine the sub-threshold voltage (sub-V TH) opera... more We utilize low-frequency noise measurements to examine the sub-threshold voltage (sub-V TH) operation of highly scaled devices. We find that the sub-V TH low-frequency noise is dominated by random telegraph noise (RTN). The RTN is exacerbated both by channel dimension scaling and reducing the gate overdrive into the sub-V TH regime. These large RTN fluctuations greatly impact circuit variability and represent a troubling obstacle that must be solved if sub-V TH operation is to become a viable solution for low-power applications.

2016 IEEE International Reliability Physics Symposium (IRPS), 2016

A methodology for the evaluation of ultra-fast interfacial traps, using jitter measurements as a ... more A methodology for the evaluation of ultra-fast interfacial traps, using jitter measurements as a probe, is developed. This methodology is applied to study the effect of PBTI stress on the density of ultra-fast electron traps (with 500 ps to 5 ns characteristic capture/emission times) in a high-k/Si nMOSFET. It is shown, that in spite of an observed increase of timing jitter after PBTI stress, this increase may not be correlated with an increasing density of interface traps. Rather, it is solely caused by a VT shift which simply decreases the output signal amplitude. The results indicate that ultra-fast (presumably interface) traps may not be affected by PBTI stress.

Analytical Chemistry, 2019

Electron spin resonance (ESR) spectroscopy measures paramagnetic free radicals, or electron spins... more Electron spin resonance (ESR) spectroscopy measures paramagnetic free radicals, or electron spins, in a variety of biological, chemical, and physical systems. Detection of diverse paramagnetic species is important in applications ranging from quantum computation to biomedical research. Countless efforts have been made to improve the sensitivity of ESR detection. However, the improvement comes at the cost of experimental accessibility. Thus, most ESR spectrometers are limited to specific sample geometries and compositions. Here, we present a non-resonant transmission line ESR probe (microstrip geometry) that effectively couples high frequency microwave magnetic field into a wide range of sample geometries and compositions. The non-resonant transmission line probe maintains detection sensitivity while increasing availability to a wider range of applications. The high frequency magnetic field homogeneity is greatly increased by positioning the sample between the microstrip signal line and the ground plane. Sample interfacing occurs via a universal sample holder which is compatible with both solid and liquid samples. The unavoidable loss in sensitivity due to the non-resonant nature of the transmission line probe (low Q) is recuperated by using a highly sensitive microwave interferometer-based detection circuit. The combination of our sensitive interferometer and non-resonant transmission line provides similar sensitivity to a commercially available ESR spectrometer equipped with a high-Q resonator. The non-resonant probe allows for transmission, reflection or dual-mode detection (transmission and reflection) where the dual-mode results in a √2 signal enhancement.

2010 Symposium on VLSI Technology, 2010

2009 IEEE International Integrated Reliability Workshop Final Report, 2009

Fast I d-V g measurements on very high performance devices (very low channel ON-resistance) and l... more Fast I d-V g measurements on very high performance devices (very low channel ON-resistance) and larger area devices (therefore large gate capacitance) are subject to serious distortions. Methods to minimize these distortions are introduced in this paper; thus expanding the applicable range of this important measurement technique.

IEEE Transactions on Electron Devices, 2015

Charge pumping (CP) has proved itself to be one of the most utilitarian methods to quantify defec... more Charge pumping (CP) has proved itself to be one of the most utilitarian methods to quantify defects in MOS devices. In the presence of low-to-moderate gate leakage, CP quantification is most often implemented via a series of measurements at multiple frequencies. However, this approach is ill-equipped to handle excessive leakage currents common in advanced technologies. In this paper, we transform multifrequency CP from a quasi-dc measurement into a true ac measurement. This ac detection scheme, called frequency-modulated CP, is far better equipped to deal with high levels of leakage currents and thereby extends the usefulness of CP to current and future device technologies where excessive leakage is the norm. Additionally, we show that multifrequency CP has a long overlooked error that becomes significant in high-leakage situations. We discuss the origins of this error in detail and outline mitigation methodologies. Finally, we explore timing and voltage limitations of waveform generators and how these experimental boundary conditions impact on both frequency-dependent and FMCP.

IEEE Transactions on Electron Devices, 2012

Frequency-dependent charge pumping (CP) (FD-CP) has emerged as a popular technique for studying t... more Frequency-dependent charge pumping (CP) (FD-CP) has emerged as a popular technique for studying the spatial and energetic distribution of defect centers in advanced high-k gate stacks. However, conflicting interpretations of the CP frequency-defect depth relationship has led to controversial and inconsistent findings between various groups. A key assumption is that most, if not all, bulk defect trapping/detrapping contributes to the CP current. In this paper, we show, experimentally using two independent measurements, that there is a large discrepancy between the total amount of bulk defect trapping/detrapping that occurs and the actual CP contribution due to these defects. We argue that the CP current due to bulk defects depends heavily upon the specific device geometry/technology, the minority-carrier lifetime, and FD-CP's general inability to function as a defect profiling tool. Index Terms-Bulk defects, charge pumping (CP), charge trapping, high-k dielectrics.

IEEE Transactions on Electron Devices, 2014

Accurate reliability predictions of real-world digital logic circuits rely heavily on the relevan... more Accurate reliability predictions of real-world digital logic circuits rely heavily on the relevancy of device-level testing. In the case of bias temperature instability (BTI), where recovery plays a significant role, a leap of faith is taken to translate device-level reliability data into a practical information for the real-world circuit implications. In this paper, we develop a methodology to bridge this gap by employing an eye diagram approach, which allows us to monitor, at circuit speed, device-level random jitter degradation in response to stress. By employing a variety of positive BTI gate voltage stress and sense bit sequences (including dc, ring oscillator (RO), and pseudorandom), we are able to compare the effectiveness of these approaches at capturing random timing jitter. We find that conventional RO-type measurements are unable to capture the random jitter degradation. This calls into question the effectiveness of using RO structures as a proxy for real-random logic circuits. Only when a pseudorandom bit sequence is employed does the true extent of jitter degradation become observable. This is an important development and serves as an accurate means to translate device-level reliability data to predict real-world digital logic circuit degradation.

Applied Physics Letters, 2008