China
Africa
Explore chapters and articles related to this topic
MEMS Devices and Thin Film-Based Sensor Applications
Published in Suman Lata Tripathi, Parvej Ahmad Alvi, Umashankar Subramaniam, Electrical and Electronic Devices, Circuits and Materials, 2021
Ashish Tiwary, Shasanka Sekhar Rout
Once the soft baking process is done, a photomask (a glass plate) is placed with a metal film pattern on the one side aligned onto the resist surface directly. Here, UV lamp produces high-intensity UV radiations and causes the metal film pattern to transport to the exposed wafer surface. Basically, three aligners primarily used for the exposure process are mentioned in Figure 15.2, which are as follows: Contact alignerProximity alignerProjection aligner.
M
Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
mask aligner system. Also called a kernel. See convolution, impulse response function, kernel. mask aligner a tool that aligns a photomask to a resist-coated wafer and then exposes the pattern of the photomask into the resist. mask biasing the process of changing the size or shape of the mask feature in order for the printed feature size to more closely match the nominal or desired feature size. mask blank a blank mask substrate (e.g., quartz) coated with an absorber (e.g., chrome), and sometimes with resist, and used to make a mask. mask linearity the relationship of printed resist feature width to mask feature width for a given process. mask programming programming a semiconductor read-only-memory (ROM) by modifying one or more of the masks used in the semiconductor manufacturing process. mask set consists of the dozen or so (varies with process and company) individual masks that are required to complete a MMIC wafer fabrication from start to finish. Examples of masks or mask levels are "first level metal" (defines all the primary metal structure on the circuit), "capacitor top plate" (defines the pattern for the metal used to form the top plate of MIM capacitors), and "dielectric etch" (defines areas where dielectric (insulator) material will be removed after coating the entire wafer with it). maskable interrupt interrupt that can be postponed to permit a higher-priority interrupt by setting mask bits in a control register. See also nonmaskable interrupt. masking a phenomenon in human vision in which two patterns P1 and P1 + P2 cannot be discriminated even though P2 is visible when seen alone. P1 is said to mask P2 . mass storage data. a storage for large amounts of
Fabrication of BioMEMS Devices
Published in Simona Badilescu, Muthukumaran Packirisamy, BioMEMS, 2016
Simona Badilescu, Muthukumaran Packirisamy
Photolithography is one of the most well-established techniques for microfabrication used to transfer a geometric pattern onto a material (silicon, glass, etc.) by selective exposure to light. The lithographic process proceeds as shown in Figure 7.8. The pattern is first drawn with a computer program and transferred onto a photomask. The photomask is usually a glass plate with an opaque material in the desired pattern. The photosensitive material (photoresist) is deposited onto a substrate such as silicon or glass by spin coating. After the deposition in the order of a few microns thickness, the substrate is heated to 60 to 100°C in order to improve the adhesion and remove the trace of solvents. This process step is called soft baking. The photoresists are thermoset polymer resins that cross-link under exposure to ultraviolet light. In the next step, called aligning, the substrate and the mask are then brought in contact in a machine called the aligner and the photoresist is exposed to a UV source. Depending on the desired resolution, UV, EUV (extreme UV), x-ray, or e-beam sources are used. Depending upon the type of photoresist, the exposed part of the photoresist under the transparent part of the mask or the unexposed part becomes soluble in the developing solution, and it is subsequently washed off. In the next step, called developing, for a positive photoresist, the exposed area becomes more soluble in the developing solution and can be easily removed. In the case of a negative photoresist, the unexposed part is removed in subsequent developing. A negative photoresist, such as SU8 when exposed to UV light, will become cross-linked and can be developed with propylenglycol monoether acetate, ethyl acetate, etc. One of the popular negative photoresist materials is called SU8 because of its monomer that contains eight epoxy groups. SU8 has proved to be a very stable material both thermally and mechanically because of the strong cross-linking that takes place during exposure to UV light. The sections of the photoresist not covered by the opaque regions of the photomask are exposed by irradiation with UV light. Generally, shorter wavelengths are recommended for higher resolution. For nanoscale lithography, x-ray, electron beam, or EUV is used.
Temperature-dependent Electrical Characterization of Single and Dual-gate Flexible Carbon Nanotube Thin Film Transistors
Published in IETE Journal of Research, 2022
M. C. Chandrashekhar, K. C. Narasimhamurthy
The polyimide tape 5413 M with silicone adhesive coated on the bottom side of thickness 75 µm, the width of 25.4 mm and length of 40 mm was pasted on silicon (Si) wafer of 2 in.. The polyimide substrate fixed on the Si wafer was preheated at 90°C for 5 min prior to the lithography process. The photolithography was accomplished by double-sided aligner DSA EVG 620. The bottom-gate pattern was transferred on to the polyimide tape as shown in Figure 1(b). Titanium/gold (Ti/Au) bottom-gate of thickness 5/50 nm was deposited by 4 target E-beam evaporator (4-TEBE), the resulting cross-sectional view of the Ti/Au deposited is shown in Figure 1(c). The patterned Ti/Au bottom-gate using photolithography is shown in Figure 1(d). The SiO2 dielectric layer of 10 nm thickness was deposited by radio frequency (RF) sputtering and patterned using photolithography is shown in Figure 1(e).
Surface hydrogeneration of vanadium dioxide nanobeam to manipulate insulator-to-metal transition using hydrogen plasma
Published in Journal of Asian Ceramic Societies, 2021
Hyunwoo Kang, Minhwan Ko, Hyobin Choi, Wanggon Lee, Ranveer Singh, Mohit Kumar, Hyungtak Seo
To measure the electrical characteristics of the nanobeams, electrical contacts were formed by the liftoff method as follows. First, hexamethyldisilane (HDMS) and 2 μm-thick photoresist (PR) was deposited on a nanobeam-deposited sample using a spin-coater. Thereafter, using a photomask and a mask-aligner, the light of the i-line wavelength band was irradiated by 80 mJ. After soft bake, the PR in the region where the electrode pads were deposited was removed by dipping it in the developing solution. Using an electron-beam (e-beam) evaporator, 3-nm-thick titanium and 50-nm-thick gold layers were deposited on the pad for metal contacts. Finally, the remaining PR was removed using acetone. A semiconductor parameter analyzer (Keithley 4200-SCS, USA) was used to measure the electrical properties in a pressure-controllable chamber equipped with probe station. The gold/chrome electrical probe was used as a top electrode. For the temperature-dependent current–voltage measurements, a heater connected with the sample stage was used. Optical microscopy (Olympus BX51M, Japan) and field-emission scanning electron microscopy (Hitachi S-4800, Japan) were used to confirm the distribution, size, and shape of the nanobeams.
Development of a walking aid with remote electrocardiogram measurement and global positioning system function
Published in Journal of the Chinese Institute of Engineers, 2021
Hsi-Chiang Chou, Chun-Yen Huang
In this study, we used Altium Designer to draw the circuit diagram, which was transformed into a printed circuit board to complete the circuit layout (Chang 2017). After completing the circuit layout, a mask aligner (or stepper) and an etching machine were used to fabricate the circuit board. The circuit elements were soldered into their positions. The finished circuit board was then tested to ensure that no errors occurred in the production process. The GPS module was connected to the Arduino MEGA using a program, after the walking aid was moved to test whether the GPS transmission output parameters changed. After the front-end system was completed, the data acquisition and wireless transmission systems were installed. The purpose of the data acquisition system was to capture ECG signals via the Arduino MEGA and then perform ADC. The Wi-Fi module was installed to transmit data to the human–machine interface. The GPS module also transferred data to the human–machine interface through the Wi-Fi module. A judgment then could be made based on the results displayed on the arrhythmia determination interface and GPS interface. Figure 14(a) presents a photograph of this system with the brass column sensors installed in the handle and pole of the walking aid (The size and weight are W30 cm*D25 cm*H88 cm, 1.3 kg). When the user held the handle, a circuit was formed, and ECG signals were detected. The plastic box at the bottom of the walking aid contains modules including the Arduino MEGA, ECG signal sensing circuit, power circuit, GPS module, and wireless Wi-Fi module (Figure 14(b)).