M. Mazalan

The effect of softbaking temperature on SU-8 photoresist performance

One of the steps required during the fabrication of SU-8 mold for soft lithography is softbaking, which is conducted after the deposition of the photoresist. The purpose of softbaking is to stabilize the resist film and eliminate any remaining solvent through evaporation. This ensures that the resist surface is non-sticking, hence avoiding debris when transferring the patterns later. In this paper, we investigate the effects of softbaking temperature on the polymerization of SU-8 photoresist. The significance of this work is to optimize the fabrication process involved in producing SU-8 mold structures with thickness of 30 μm. This project involves a series of experiments covering softbaking temperatures ranging from 45° to 115° C. Experiments results show that softbaking temperature of 85°C results in completely stick and crack free structures. By this, a huge improvement obtained if compared to the result of processing at the standard soft bake temperature of 95°C. The soft bake temperature should not be taken lightly while optimizing SU-8 processing because it has a big influence on the material properties and the lithographic performance of the resist.

Etch Performance of KRF Excimer Laser Micromachining Characterization on Silicon Material

Excimer laser micromachining enables us to overcome the conventional lithography-based microfabrication limitations and simplify the process of creating three dimensional (3D) microstructures.The objective of this study is to investigate the relation between the number of laser pulses, number of laser passes through the channel of ablation site and their etch performance. Parameters such as frequency, fluence and velocity were retained as constants. In this paper, we present a parametric characterization study on silicon using KrF excimer laser micromachining. From the result, the etch rate change were recorded as the two major laser parameters (Number of laser pulses and number of laser passes) were varied. Both parameters were showing declination profile however from comparing both graphs, it showed that etch rate dropped more steeply when varied number of laser passes rather than number of pulses.

Characterization of MEMS structure on silicon wafer using KrF excimer laser micromachining

This paper presents preliminary parametric studies of KrF laser micromachining ablation effects on Silicon. Four parameters are studied, namely laser energy, pulse rate, number of laser pulses, and Rectangular Variable Aperture (RVA) in X and Y direction. At present, the study is focused on the production of microchannels using laser micromachine, in which its dimension is examined and measured. We found that the number of laser pulse is non-linearly proportional with the ablated channel width, with the etching rate of approximately 1 to 5 um for 50 laser pulses. This is similar with the measured depth of the microchannel. The changes in the measured channel width are most significant when the laser energy is increased. Some debris and recast can also be observed around the edge of the microchannel particularly during the variation of the laser pulse frequency. When varying the RVA, it is observed that the surfaces of the ablated microchannels are not smooth with a lot of debris accumulated at the channel edge and a few discolorations. Finally, a microcantilever structure is fabricated with the aim of demonstrating the capability of the laser micromachine.

A design of 5.2 GHz CMOS up-conversion mixer with IF input active balun

This paper presents a high linearity and low power up-conversion mixer at 5.2 GHz for wireless applications. The design based on Gilbert-cell active double-balanced mixer with integrated on-chip input active balun. Core mixer employs additional parallel capacitors and the degeneration inductors to obtain high linearity. A designed active balun which converts single-ended input to differential signals for 100 MHz intermediate frequency (IF) is proposed. The up-conversion mixer converts an input of 100 MHz IF signal to an output of 5.2 GHz radio frequency (RF) signal with a local oscillator (LO) frequency of 5.1 GHz. The simulation results indicated that the proposed method shows the conversion gain of 6-dB, the input third order intercept point (IIP3) of 8-Bm, and 2.48-mW power consumption at 1.8-V power supply.

Consideration of Factors Towards Lowering the Natural Frequency of MEMS Based Cantilever Structure: Top Mass versus Back Etch Design

The ability to self-energize wireless sensor node promote the popularity of energy harvesting technique especially by using ambient vibration as the source of energy. In addition, the successful integration of the energy harvesting element on the same wafer as a wireless sensor node will promote the production in the MEMS scale and will reduce the overall cost of production. The usage of the cantilever structure as the transducer for converting mechanical energy (vibration) due to deflection of cantilever into the electrical energy is possible by depositing piezoelectric material on the cantilever. The usage of cantilever provide the simplest way for fabrication in the MEMS scale and also provide the ability to achieve low natural frequency. This paper present the work done on the simulation of the cantilever structure with the top end and back etch proof mass towards achieving low natural frequency in the MEMS scale by using IntelliSuite software.

Materialization of MEMS in a collaborative AMBIENCE: A UniMAP experience

Micro Electro Mechanical System (MEMS) is an emerging engineering field that owes so much to material and its processing technologies. It is proven to be capable of enhancing the performance of many devices traditionally produced using conventional microscale manufacturing methods. However, the manufacturing involves requires quite substantial investment in which is normally a major obstacle for universities. Universiti Malaysia Perlis (UniMAP), being a relative new in Malaysia, innovative and collaborative effort are explored with outside organization to overcome this obstacle. Leveraging on its close relationship with the industries, UniMAP collaborated with industries and other critical non-academic partners to plan set-up and launch the first industry driven MEMS based centre of excellent in Malaysian universities. It is named AMBIENCE (Advanced Multidisciplinary MEMS Based Integrated Electronic NCER Centre of Excellence). This paper elaborates in the collaboration history, contribution planning, physical set-up, capabilities and success stories of a new industry driven centre of excellence in UniMAP.

Development of a read-out circuitry for piezoresistive microcantilever electrical properties measurement

This paper reports on the development of a piezoresistive microcantilever sensor read-out circuitry to detect acceleration, biological or chemical activities. Laser micromachining technique is used in fabricating the piezoresistive microcantilever sensor as well as assisting in the cantilever beam and piezoresistor shape formation. In order to test the sensor performance, a Wheatstone bridge which acts as resistive sensor is integrated with three other resistors and the fabricated sensor. A set of amplifier circuit consisting of INA128 is developed to amplify and extract the electrical signal component of the bridge circuit. The resistance and output voltage characteristic of the Wheatstone bridge is investigated, where the percentages difference between the calculated and measured output voltage is very low and similar to each other. The sensor response to vibration is also studied using an electro-dynamic vibration system. The system is designed specifically to enable the accessibility of a small resistivity change due to outside reaction.

Towards improving the etch performance of KrF excimer laser micromachining on silicon material

Excimer laser micromachining enables us to overcome the conventional lithography-based microfabrication limitations and simplify the process of creating three dimensional (3D) microstructures. The objective of these study are to investigate the relation between frequency (f), number of laser pulse (P), fluence (F) and their etch performance. This paper presents a parametric characterization study on silicon using KrF excimer laser micromachining. From the result, the etch rate change were recorded as the three major laser parameters (frequency, number of pulse and fluence) were varied. From the results, we found that the fluence has the highest influence on silicon etching rate due to factors of photothermal and photochemical, while frequency and the number of laser pulses do not change the energy.

Performance Analysis of Varied Dimensions Piezoelectric Energy Harvester

Thin film piezoelectric material plays a vital role in micro-electromechanical systems (MEMS), due to its low power requirements and the availability of high energy harvesting. Zinc oxide is selected for piezoelectric material because of its high piezoelectric coupling coefficient, easy to deposit on silicon substrate and excellent adhesion. Deposited ZnO and Al improve the electrical properties, electrical conductivity and thermal stability. The design, fabrication and experimental test of fabricated MEMS piezoelectric cantilever beams operating in d33 mode were presented in this paper. PVD (Physical Vapor Deposition) was selected as the deposition method for aluminium while spincoating was chosen to deposit ZnO thin film. The piezoelectric cantilever beam is arranged with self-developed experimental setup consisting of DC motor and oscilloscope. Based on experimental result, the longer length of piezoelectric cantilever beam produce higher output voltage at oscilloscope. The piezoelectric cantilevers generated output voltages which were from 2.2 mV to 8.8 mV at 50 Hz operation frequency. One of four samples achieved in range of desired output voltage, 1-3 mV and the rest samples produced a higher output voltage. The output voltage is adequate for a very low power wireless sensing nodes as a substitute energy source to classic batteries.

Coupling Gap Analysis of Microring Photonic Wavelength Switch

Microring resonators side coupled to signal waveguides provide compact, narrow band, and large free spectral range photonic channel dropping wavelength switch. Wavelength switch with improved passband characteristics and larger out-of-band signal rejection are realized through the coupling of rings. The analysis of these devices is demonstrated by the novel method of coupling. The response of switch comprised of different coupling gap may be written down by attenuation ratio.