Chiranut Sa-ngiamsak

Spectral imaging analysis for silkworm gender classification

We examine the effect of different wavelength spectra in the performance of our optical penetration-based silkworm pupa sex identification system. With available low-cost light emitting diodes (LEDs), each emitting different wavelength spectra at 468 nm, 565 nm, 639 nm, 940 nm, and broad white light, we find that the body of the silkworm pupa can block blue and near infrared light while allowing green and red light pass through. In particular, the red light can clearly highlight an important organ called “chitin gland” of the female, leading to high accuracy of silkworm gender identification. In our experiment with 120 silkworm pupae, measured high average 92.8% and lower average 87.5% accuracies in identifying silkworm gender are obtained under red and white light LEDs, respectively.

CONFINED-CHALCOGENIDE PHASE CHANGE MEMORY WITH THIN METAL INTERLAYER FOR LOW RESET CURRENT BY FINITE ELEMENT MODELING

This paper reports on the confined-chalcogenide phase change memory with thin metal interlayer (CCTMI) with the operating reset current of 0.6mA-30ns. This cell offers low reset current with simple architecture and fabrication. Thermal and heat flux distribution of both the normal-bottom-contact (NBC) and a proposed CCTMI PCM cells were carefully analyzed and simulated by two-dimensional finite element modeling. It is intriguingly found that the reset operation current of the CCTMI cell is 44% lower than that of the NBC. CCTMI has capability to solve an over-programming fail issue due to confined heat dissipation in active area.

Improvement of light penetration based silkworm gender identification with confined regions of interest

Based on our previous work on light penetration-based silkworm gender identification, we find that unwanted optical noises scattering from the surrounding area near the silkworm pupa and the transparent support are sometimes analyzed and misinterpreted leading to incorrect silkworm gender identification. To alleviate this issue, we place a small rectangular hole on a transparent support so that it not only helps the user precisely place the silkworm pupa but also functions as a region of interest (ROI) for blocking unwanted optical noises and for roughly locating the abdomen region in the image for ease of image processing. Apart from the external ROI, we also assign a smaller ROI inside the image in order to remove strong scattering light from all edges of the external ROI and at the same time speed up our image processing operations. With only the external ROI in function, our experiment shows a measured 86% total accuracy in identifying gender of 120 silkworm pupae with a measured average processing time of 38 ms. Combining the external ROI and the image ROI together revamps the total accuracy in identifying the silkworm gender to 95% with a measured faster 18 ms processing time.

Confined-chalcogenide phase-change memory with thin metal oxide interlayer for low reset current operation

A confined-chalcogenide phase-change memory (CC) with thin metal oxide interlayer (TMOI) aimed to lowering the reset current is proposed in this paper. This proposed structure offer a reduction of the reset current by 65%, 50% and 34.38% in comparison with a normal-bottom-contact (NBC) cell, CC cell and NBC with TMOI cell, respectively. The electrical and thermal characteristics were investigated by using finite element modeling based on electro-thermal physics. It is intriguingly found that the resent current of the proposed cell is significantly reduced by inserting a thin metal oxide (TiO2) film in the middle Ge2Sb2Te5 (GST) and in between GST and TiN heater. Furthermore, the melting shapes and effect of quench speed on the memory cell is also discussed. This implies the high-speed and low-power consumption CC with TMOI cell structure that can hold a promise as a future technology as memory devices.

Comparison of electromigration for lead-free solder joints of Cu vs. Ni UBM flip chip structure

Flip chip solder joints made with Cu and Ni underbump metallurgy (UBM) on the chip under current stressing were studied. The effects of material and various thicknesses (5, 10, 15, and 20 µm) of UBM on reliability were investigated. The solder material used was lead-free (Sn4.0Ag0.5Cu). Time to failure of both cases (Cu and Ni UBMs) was forecasted through the physical damage occurring at the bump under current stressing by using two-dimensional Finite Element Method (FEM). The simulation results conclude that thicker UBM can enhance electromigration reliability. Moreover, the comparison of the time to failure between Cu UBM structure with that of Ni UBM structure indicates that the time to failure of the flip chip solder joint with Cu UBM structure is approximately 5% longer than the case of Ni UBM structure due to the lowering current crowding effect at Cu UBM in the solder joint which is clearly shown in the simulations.

Technical program chairs' message

Welcome to the 19th IEEE International Symposium on Intelligent Signal Processing and Communication Systems (ISPACS), being held December 7–9, 2011 in Chiang Mai, Thailand. I would like to encourage you all to attend and actively participate in the symposium.

Comparison on the performance of the confined-chacogenide with thin metal interlayer and optimised lateral phase change memories

This work, for the first time, presents the performance comparison between the lately proposed vertical confined-chacogenide phase change memory with thin metal interlayer (CCTMI) and a newly proposed optimised lateral (LP) phase change random access memory structure with a 180nm feature size. High programming current has been a critical challenge to realize a high-density. Comparison of its performance aimed on the programming power during the reset state of both technologies was carefully analysed and simulated by 3-D Finite Element Method. The results revealed that the newly proposed LP cell with optimised structure can generate heat 52% more effective than that of CCTMI.

Three-dimensional numerical simulation of electrostatic discharge sensitivity for phase-change memories

The sensitivity to electrostatic discharge (ESD) events of the phase change memory was investigated by using a three-dimensional finite element modeling based on electro-thermal physics. Analytical storage elements were tested on µ-trench structure during three ESD models stress, HBM model, MM model, and CDM model. It was found that the phase-change memory cell is failure when All ESD model voltage stress lower than 5V. The phase change memory cell must then be considered as very sensitive class-0 devices for HBM model, class-M1 for MM model and class-C1 for CDM model.

Pinned layer reversal effect on tunneling magnetoresistive heads caused by dynamic fly height heater voltage

Pinned layer reversal (PLR) causes instability upon magnetic recording heads. PLR effects on giant magnetoresistive heads are well understood unlike tunneling magnetoresistive heads. Dynamic fly height (DFH) heater is used as a controller of the flying height of the head. This work presents the PLR phenomenon caused by DFH heater voltage. Experimental results reveal the threshold voltage of DFH heater inducing PLR phenomenon is 3.35Vwhich is lower than that of the oxide breakdown. Effect of direction and read biasing voltage level was also investigated.

Effects of ESD and EMI on TMR heads during bonding process of gold ball bonding machines

ESD and EMI are important issue in HDD. Ball bond machine makes a micro electrical connection; and this involves high voltage and high frequency current. Other works had only investigated ESD effect. This work newly presents the investigation of the severity of both ESD and EMI on MR heads. Discharge current was captured by a current transducer. EMI effect was monitored using finite integral. The experiments show discharge current was as high as few A. EMI simulations illustrate interference on a current transducer. The benefit of this work leads to higher accuracy in measurement at high frequency range.