Deposition of thin and uniform photoresist on three-dimensional structures using fast flow in spray coating

Singh, Vijay Kumar; Sasaki, Masahide; Hane, Kazuhiro; Watanabe, Yoshihiko; Takamatsu, Hirosuke; Kawakita, M.; Hayashi, Hiroki

doi:10.1088/0960-1317/15/12/016

Cited by 33 publications

(32 citation statements)

References 24 publications

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“…These experimental results about the spraying PR film on the tube surface are generally in accordance with the previous reports [1,2]. However, considering the size of tube is very small compared to those of the spray jet and the nozzle/tube distance.…”

Section: Spray Coating System For Cylindrical Substratesupporting

confidence: 91%

Lab-on-a-Tube Surface Micromachining Technology

Yang¹,

Zhang²

2017

Thin Film Processes - Artifacts on Surface Phenomena and Technological Facets

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In this chapter, the lab-on-a-tube surface micromachining technology will be used to fabricate a flexible implantable microtemperature sensor for hyperthermia application and a three-electrode system on a polymer tube surface for glucose monitoring application. This micromachining process is based on two homemade equipments: a spray coating equipment and a programmable UV 3D projection lithography system with alignment. In the spray coating system, there is a heater nozzle next to the spray nozzle for real-time heating. Pure nitrogen is flowed through the heater nozzle, warmed up and sprayed onto the tube substrate surface. The programmable UV lithography equipment for cylindrical substrate mainly consists of four parts: a uniform illumination system, a reduced projection lithography system, a synchronized motion stage system, and a Charge-Coupled Device (CCD) multilayer alignment system which is used to observe simultaneously the projected mask's patterns and those ever fabricated on the tube. Using the developed labon-a-tube surface micromachining technology, an implantable flexible microtemperature sensor and a three-electrode microstructure are successfully fabricated on the flexible polymer tube with 330 μm outer diameter, respectively. The test temperature coefficient of resistance (TCR) of the temperature sensor is 0.0034/°C. The measured cyclic voltammetry curve shows that the three-electrode system has a good redox property.

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Section: Spray Coating System For Cylindrical Substratesupporting

confidence: 91%

Lab-on-a-Tube Surface Micromachining Technology

Yang¹,

Zhang²

2017

Thin Film Processes - Artifacts on Surface Phenomena and Technological Facets

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“…To address this problem, the spray coating method is employed in this research. This method is commonly applied to slanted surfaces, which is represented by (111) silicon surface etched by alkali etching material, and the spray conditions and results are investigated and discussed in detail (9)- (13) . However, there has been little research done in applying this method to a real vertical structure having a high aspect ratio in which the sidewall is over 100 µm in height.…”

Section: Purposementioning

confidence: 99%

Fabrication of MOSFET Capacitive Sensor using Spray Coating Method

et al. 2007

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A capacitive MOSFET sensor using a SOI wafer for detecting vertical force applied to its floating gate is proposed. This sensor detects the displacement from changes in drain current, and this current can be amplified electrically by adding the voltage to the gate, i.e., MOSFET itself serves as mechanical sensor structure as shown in Fig. 1. By using a SOI wafer having a thick active silicon layer, a thick gate structure is made possible, which increases the sensitivity in accelerometer application by weighting a proof mass.The proposed fabrication process is shown in Fig. 2. Spincoating photoresist is not applicable due to the large step height of the gate structure on wafer surface. Therefore, spray coating method is employed. This method is commonly applied to slanted surfaces: however, there has been little research done in applying this method to a real vertical structure having a high aspect ratio in which the sidewall is over 100 µm in height. Basic performance of spray coating of photoresist on such structure is investigated. Figure 3 shows the results varying the moving speed of substrate. Although the speed is limited to 99 mm/s of the apparatus' maximum performance, the effect of increasing it on the photoresist uniformity is confirmed. It may be because if the speed of substrate were fast, fluctuating photoresist particles cannot stay in the neighborhood of the concave corner. Figure 4 shows the results varying the substrate temperature. The effect of increasing it on the photoresist uniformity is confirmed. It may be because if the substrate temperature were high, the particles are rapidly dry, which may effective in preventing them from migrating to the concave corner.A practical test device of MOSFET sensor is under development by using this method, and aluminum electrodes for drain, source and gate areas are successfully patterned as shown in Fig. 5. MemberA capacitive MOSFET sensor using a SOI wafer for detecting vertical force applied to its floating gate is herein proposed. A MOSFET is fabricated on a SOI wafer, and the box oxide under the gate is removed to release the gate structure. This sensor detects the displacement of the movable gate electrode from changes in drain current, and this current can be amplified electrically by adding voltage to the gate, i.e., the MOSFET itself serves as a mechanical sensor structure. By using a SOI wafer having a thick active silicon layer, a thick gate structure is made possible, which increases the mechanical stiffness and durability, and increases the sensitivity in accelerometer application by weighting a proof mass. During the fabrication process of this sensor, it is necessary that photoresist be coated on the top-surface and sidewall of the vertical pillar structure with a high aspect ratio. To address this problem, photoresist is applied using spray coating. The uniform coating is successfully realized by adjusting the moving speed of the substrate, and the substrate temperature. A practical test device is under development using this method, and...

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“…The photoresist reflow [5], and the electrostatic force shape modulation [6] have also been reported to form the microlens of various shape. So far the available 3D lens shapes are still limited by the process technology, for example the photolithography on a highly structured substrate surface [7].…”

Section: Introductionmentioning

confidence: 99%

Formation and curvature tuning of micro lens using surface tension and hydraulic pressure assisted molding process

Hsu

Lee

Fang

2013

2013 IEEE 26th International Conference on Micro Electro Mechanical Systems (MEMS)

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This study presents a novel concept for the formation of curvature micro lens and the lens-curvature tuning using the hydraulic pressure and surface tension assisted molding process. The liquid UV-curable polymer is defined by hydraulic pressure, surface tension, and molding, and then solidified by UV-light to form the micro-lens. Merits of the process technology are: (1) initial lens curvatures defined by the polymer volume and surface tension, (2) final lens curvature is tuned by the hydraulic pressure, and (3) optical pattern (Fresnel zone) can be defined by molding. In applications, the biconvex, biconcave, and convex-concave lens, and the curved Fresnel lens are demonstrated. The lens radius of curvature R c is varying from -0.58mm to 1.5mm. The integration of micro-lens with magnet holder for actuation is also demonstrated.

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Deposition of thin and uniform photoresist on three-dimensional structures using fast flow in spray coating

Cited by 33 publications

References 24 publications

Lab-on-a-Tube Surface Micromachining Technology

Lab-on-a-Tube Surface Micromachining Technology

Fabrication of MOSFET Capacitive Sensor using Spray Coating Method

Formation and curvature tuning of micro lens using surface tension and hydraulic pressure assisted molding process

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