Papers by Author: Susumu Sugiyama

Abstract: In this paper, a nanofabrication technology of alumina self-organization method for deep and self-arranged nanometer holes on high purity aluminum is presented. Deep and self-arranged nanometer holes can be used as antireflection structures, polarizing elements, guided-mode resonance filters and high efficiency diffraction optical elements. The fabrication technology provided an effective method for low-cost, large-scale manufacturing high aspect ratio nanoholes.The deep nanoholes structure is fabricated by two anodizing processes on aluminum. The theoretical calculation of reflectivity for the fabricated deep holes G-solver sofeware while the measurement setup for the reflectivity of the deep nanoholes is self-made optical parameter test system.The results show that the calculated reflectivity of the deep holes is below 8.0% within the visible wavelength range, while the measured reflectivity of the fabricated nanometer holes is under 8.30% within the wavelength range of 400-760nm and it agrees well with the theoretical analysis result.

Abstract: Two methods for fabricating hollow micro needle arrays have been described. One method is that fabricating hollow micro needle array based on double X-ray exposures-----one exposure is normal X-ray exposure with X-ray mask and the other is X-ray exposure without X-ray mask. The other method is based on moving mask X-ray exposures plus an alignment X-ray exposure. The feasibilities for the hollow micro needle arrays were demonstrated by fabricating 25 micro needles in a 5x5 mm2 polymer chip.

Abstract: The PZT is used for piezoelectric actuators that have high area efficiency but no good machinability. A direct writing micro structures on PZT wafer by excimer laser micromaching method has been proposed and confirmed. PZT nano-needle structures have also been fabricated by the direct writing method only by changing the laser micromachiong process parameters. The fabricated nano-needle structures can be very useful because of the need for studies on ferroelectric size effects as well as for potential applications such as ultra-high density memory devices.The relationship of process depth with the excimer laser parameters has been tested.

Abstract: Piezoelectric energy harvester with high output and low resonant frequency is required in wireless sensors and portable devices. It can be fabricated by bonding of the bulk PZT ceramics with excellent piezoelectric properties to the Si wafer. Firstly, the basic design principles of piezoelectric energy harvester were analyzed. Then, the novel process flow to manufacture piezoelectric energy harvester using bulk PZT was explored. Using 2µm Au layer as the bonding layer, the bulk PZT was bonded to Si wafer at the temperature of 5500C for 2 hours. With the lapping technique, the thickness of bulk PZT is reduced from 300µm to 60µm. KOH was used to etch the backside of Si from 500µm to 20µm as the supporting layer of the piezoelectric beam. The last procedure was to dice the wafer into many cantilevers with different length or width. One of PZT piezoelectric cantilevers was tested using a mechanical shaker, by applying a sinusoidal oscillation at different frequencies. The resonant frequency is 815 Hz, and the voltage output is around 632 mV at 0.5g. The result shows that the sample has excellent ability to harvest energy of vibration and the novel bonding technology is quite feasible.

Abstract: The paper reports on the PZT thick films preparation method by bonding bulk PZT on Si and then lapping PZT to suitable thicknesses. Epoxy resins with preferable thermostability were used as the intermediate adhesive layer in bonding process. A tight bonding of more than 10MPa was attained at suitable gradient bonding temperatures in an oven which were from 30 oC up to 105 oC according to 15 oC per thirty minutes and holding for more than 3h at 105 oC, and a pressure of more than 0.05MPa. Some properties of the prepared PZT thick films were tested. Finally, a piezoelectric MEMS power generator was fabricated by using the described techniques of PZT thick films preparation on silicon. The maximum output voltage under the resonant operation was measured.

Abstract: Poly(methyl methacrylate)(PMMA) and Poly L-lactic acid (PLLA) are transparent and they are suitable for optical purposes. The multi-layer polymer microfabrication can be applied for a large displacement actuator and precision sensors. A new method is intruduced to generate the multi-layer polymers microstructures by X-ray lithography with alignment. The function of X-ray on polymer materials are breaking the polymer main chain and generating intermediates which can be degraded further and finally dissolved by the solvent interaction. The method for polymer micromachining by using X-ray lithography with alignment for fabrication multi-layer micro polymer structures is confirmed experimentatively.

Abstract: Piezoelectric sensor can produce voltage when deflected (function as an energy harvester) while piezoelectric actuator can deflect when a voltage is applied. Different device applications have different requirements on the thickness and in-plane geometry of the Lead Zirconate Titanate(PZT) piezoelectric layers and thus have their own processing difficulties. In this paper, PZT-Au-Si cantilever is fabricated by eutectic bonding and dicing process.The properties of lapped PZT ceramics and silicon cantilever is also evaluated. The PZT-Au-Si cantilever applications for both piezoelectric actuators and energy harvesters have been confirmed.

Abstract: As an energy conversion material, piezoelectric ceramic lead zirconate titanate (PZT) has been used in a wide range of areas. And a PZT wafer bonding with a silicon wafer technology is a promising method to fabricate micro-sensors and micro-actuators using well-established silicon machining techniques. In order to obtain the excellent piezoelectricity and suitable thickness from the bulk PZT, a method is presented. It is to bond a bulk PZT onto a silicon wafer via an intermediate layer. In this paper, two bonding methods are presented. One is to bond a bulk PZT with a silicon wafer by anodic bonding technique using a thin glass film as the intermediate layer. The other is to bond a bulk PZT with a silicon wafer by eutectic bonding using a thin gold film as the intermediate layer. The glass film is 2µm in thickness, deposited by sputtered method. Anodic bonding conditions are: 0.8MPa in pressure, 500 oC in temperature, 250V in voltage and different bonding time. The bonding strength test shows that the maximum bond strength is 13.93 MPa when the bonding time was 60 min. It is void-free structure in the interface of the PZT-Glass-Si structure. The gold film is 1.6µm in thickness, deposited by evaporation method. The eutectic bonding conditions are: 0.8MPa in pressure, 500 oC in temperature, and different bonding time. The bond strength of the PZT-Au-Si structure was tested and the maximum value was 13.19 MPa when the bonding time was 60 min.