Shankar Dutta

This paper presents etching optimization of comb structure formation in small silicon substrates mounted on a large silicon wafer (150 mm diameter) using the S1818 photoresist adhesive layer. A series of deep reactive ion etching (DRIE) experiments are done by varying the etching conditions and tweaking the baking schedule of the photoresist adhesi...

This paper discusses the design and fabrication of MEMS differential capacitive accelerometer (z-axis sensitive) structure. The accelerometer structure consists of one each movable and reference capacitors in the single accelerometer die fabricated using highly conductive (p-type, resistivity: 0.001 Ω cm) SOI substrate. Resonant frequencies of the...

This paper discusses the evaluation and testing of MEMS capacitive accelerometer (z-axis sensitive) fabricated using silicon-on-insulator (SOI) wafer. The accelerometer structure consists of highly conductive (p-type, resistivity: 0.001 Ω-cm) silicon proof mass (1000 μm × 1000 μm × 30 μm) suspended by four crab-like L-shaped beams (1150 μm × 30 μm...

Precise investigational model of a capacitive micromachined ultrasonic transducer (CMUT) is offered for assessing membrane displacement along with the impact of the top electrode. Silicon nitride (Si3N4) selected as membrane material is operated under a DC bias. The top electrode's size and material characteristics are varied in this study to inspe...

The study of a micro-electro-mechanical-system (MEMS) based capacitive micromachined ultrasonic transducer (CMUT) is considered. The characteristics and behavioral studies of circular, hexagonal and square designed membranes are achieved. The circular CMUT provided better performance regarding membrane displacement, frequency and capacitance profil...

MEMS based inertial switches have important applications in defense, automobile, and aviation sectors. The materials for these inertial switches are either metals or low-resistivity silicon. This paper discussed about the amalgamation of metal and silicon in the MEMS inertial switch (500 g) structure to achieve high performance and high current han...

An immersion based Capacitive Micromachined Ultrasonic Transducer (CMUT) is modelled and investigated. Analysis on the displacement and output pressure is done using Finite Element Method (FEM) for different parameters of membrane thickness, gap thickness, width of the membrane, liquid material and bias voltage applied. With effectively optimizing...

Functional flexible piezo-resonators are of vital interest for designing micro-electrometrical system (MEMS) based high-frequency wearable devices. The magnetoelectric (ME) heterostructure comprising highly magnetostrictive Ni–Mn–In and piezoelectric AlN films was fabricated over flexible substrates to develop the bulk acoustic wave (BAW) resonator...

This paper presents the capacitive behaviour of a Capacitive Micromachined Ultrasound Transducer (CMUT). A Finite Element Method (FEM)-based simulation is proposed to characterize the capacitance of CMUT with different geometrical parameters. The structure of the CMUT under scrutiny consists of an aluminum top electrode on a thin movable membrane o...

Nanostructures or microstructure-patterned based metamaterials are fabricated on semiconductors’ surface to reduce the reflection and enhance the absorption of light. There is a particular interest to develop the infrared (IR) absorbers’ materials that will improve the absorption in IR detector. This paper discusses about the mechanism of broadband...

This paper investigates the dielectric properties of ultrathin TiOx-SiOx nanocomposite films (~20 nm) for futuristic electronic and MEMS sensor applications. The nanocomposite films are prepared by thermal annealing of sputtered TiO2 films on p-type Si (100) substrates. The annealing process is done at 700 °C for 10–45 min. Post-annealing, the film...

Nanostructures and microstructures are fabricated on silicon surfaces to reduce the reflection and enhance the absorption of light. It can be used to improve infrared (IR) absorption-based MEMS bolometer applications. The cost-effective metal-assisted chemical etching (MACE) method is used to synthesize the silicon nanowires arrays for surface roug...

High quality capacitive accelerometers with appreciable operation bandwidth are being employed in different high-end defence applications. This paper discusses a novel concept of introducing microchannels in the push-pull capacitive accelerometer structure to control the damping arising due to squeeze film effect. The width and depth of the microch...

In this work, the response of the z-axis differential capacitive MEMS accelerometer structure is studied under mechanical shock. The resonant frequency of the accelerometer is 9.12 kHz, and the corresponding time-period (Tn) is 0.11 ms. Simulation of the accelerometer structure under 30 g half-sine acceleration shocks of different durations (0.1–4...

This paper reports two specific aspects of Si implantation in the molecular beam epitaxy grown p-type GaSb epilayer, namely the evolution of nanoporosity and doping characteristics. The implantation is done with 100 keV Si ions at four different fluences, i.e, 5x1013, 1x1014, 5x1014 and 1x1015ions/ cm2 . Field emission scanning electron microscope...

Aluminium nitride-based MEMS resonators are one of the interesting recent research topics for its tremendous potential in a wide variety of applications. This paper focuses on the detrimental effect of residual stress on the AlN-based MEMS resonator design for acoustic applications. The residual stress in the sputtered c-axis (< 001 >) preferred or...

Micro-electro-mechanical system (MEMS) technology has radically changed the scale, performance, and cost of a wide variety of sensors and actuators by taking advantage of batch fabrication. The multidisciplinary nature of MEMS employs knowledge of diverse technical areas to realize improved and novel transducer systems. This also brings various ass...

Aluminum nitride-based MEMS resonators are one of the interesting recent research topics for its tremendous potential in a wide variety of applications. This paper focuses on the detrimental effect of residual stress on the AlN based MEMS resonator design for acoustic applications. The residual stress in the sputtered c axis (<001>) preferred orien...

X-ray diffraction (XRD) techniques are powerful, non-destructive characterization tool with minimal sample preparation. XRD provides the first information about the materials phases, crystalline structure, average crystallite size, micro and macro strain, orientation parameter, texture coefficient, degree of crystallinity, crystal defects etc. XRD...

Abstract This paper presents the structural, optical, and electrical characteristics of AlN thin films on Si (111) substrate grown by DC magnetron sputtering technique for MEMS applications. The grown AlN thin films (thickness: 680, 900, and 1200 nm) exhibited polycrystalline wurtzite structure with preferred orientations along <001> directions. Th...

In this work, the tunable resistive switching (RS) functionality of a Cu/MoS2/AlN/ITO nanostructured device is systematically investigated in dark and white light illumination. The device exhibits bi-state RS behavior in the dark ambient, whereas light illumination induces an extra intermediate resistance state and provides controllable tri-state R...

Molybdenum Trioxide (MoO3) films are grown on Si(100) substrates by reactive RF magnetron sputtering in plasma containing a mixture of Argon and Oxygen, using a pure Molybdenum target. In this paper, we report the deposition of (MoO3) films on Si(100) substrates under varying gas flow (O2 + Ar gas) (20 sccm to 30 sccm with the duration of depositio...

This paper discusses the growth and evolution of residual stresses in (0002) preferentially oriented aluminum nitride (AlN) layers on Si (111) wafers by sputtering technique for the development of micro-electro-mechanical system (MEMS) accelerometer. The microstructure of the deposited films exhibited vertical columnar structures. Residual stresses...

In this report, the ferromagnetic shape memory alloy (Ni50Mn35In15) and Pb0.96La0.04Zr0.52Ti0.48O3 based bilayer (Ni-Mn-In/PLZT (260 nm/300 nm)), trilayer (Ni-Mn-In/PLZT/Ni-Mn-In (130 nm/300 nm/130 nm)) and four-layer (Ni-Mn-In/PLZT/Ni-Mn-In/PLZT (130 nm/150 nm/130 nm/150 nm)) multiferroic heterostructures with equal thickness ratios have been fabr...

This paper presents the feasibility of non-stoichiometric TiOx thin films as an active material for bolometer application. The TiOx films have been deposited on glass substrate by DC sputtering with oxygen flow rate of 0.1–0.7 sccm at room temperature and their electrical properties have been studied. The TiOx films were found to be amorphous with...

The presence of residual stress is inevitable and major constraint for MEMS devices as they induce deformation, fracture, fatigue and micro structural changes in the structure. This paper presents the influence of residual stresses (up to − 2100 MPa) on the performance of AlN based piezoelectric MEMS accelerometer structure. The MEMS structure cons...

This paper discusses about the fabrication of comb-structure with vertical sidewall profile by wet chemical etching of Si (110) substrate in boiling KOH solution. Etch rate of the Si (110) substrate in boiling KOH solution is 9 times higher with a 40X reduction of average surface roughness than the etch rate at 75 °C. An etch selectivity of 48:1 fo...

This paper presents improved W-band (75–110 GHz) radio frequency characteristics of micro-electromechanical switches in T and π-matched configurations. The switch structures consist of Au metallic bridge (s) suspended over the coplanar waveguide (CPW) signal line drawn on quartz substrate. Here, a high impedance transmission line is introduced on b...

The paper reports on process design for fabrication of a navigational grade ±30 g MEMS capacitive push-pull accelerometer based on SOI (Silicon-On-Insulator) technology using Pyrex Glass-Silicon-Pyrex Glass multi-stack. The accelerometer structure is fabricated by DWP (Dissolve Wafer Process) technique. The complete fabrication process and released...

This paper presents the effect of residual stress on the response of the capacitive push pull accelerometer structure. The effect of residual stresses on the structure was simulated by using finite element method (FEM) based software. A simple model is proposed to trim the offset of the accelerometer deflection due to the residual stress associated...

To employ the MEMS device for navigational purpose; temperature stability, bias stability and linearity are the key parameters. In present paper, the effect of temperature variation on the output of z-axis capacitive accelerometer is discussed. In absence of any temperature compensation (TC) circuit, the accelerometer exhibited an out-put variation...

This paper presents the effect of vacuum packaging on the band-width of push–pull type capacitive accelerometer structure. The accelerometer structure (for ± 30 g application) consists of silicon proof mass (1000 μm × 1000 μm × 30 μm) suspended by four L-shaped beams over 1 μm deep cavity. The fixed electrodes (Au) are on Pyrex glass substrates whi...

This paper discussed about the morphological and electrical properties of c-axis oriented aluminium nitride (AlN) thin films grown on Si (100) and Si (110) substrates by direct current (DC) reactive sputtering technique. Both the films showed intense (002) peak with the texture coefficient (γ) of 3.1 and 2.8 corresponding to Si (100) and (110) subs...

The present study reports the effect of bottom electrodes (Al, Pt & Ti) on the texture, piezoelectric characteristics, dielectric properties and leakage current behavior of reactive DC magnetron sputtered AlN thin films. X-ray diffraction results revealed that the lattice structure and texture of bottom electrode plays a vital role in c-axis wurtzi...

Aluminum nitride (AlN) films were grown on Si substrates by dc magnetron sputtering in plasma containing a mixture of argon and nitrogen, using a pure aluminum target. In this paper, we studied the growth of AlN films on Si(100) substrates under varying gas ratio (N2 to Ar gas ratio) by DC reactive magnetron sputtering at moderate deposition temper...

This paper presents the effect of incorporation of Ni-substitution (0–20 at %) on structural, morphological and mechanical properties of BiFeO3 films. The films are found to be in polycrystalline perovskite phase with no additional NiO phase. The (012) and (110) x-ray diffraction peaks of the films are found to be gradually shifting towards the low...

This paper discussed about the integration issues of Pb (Zr0.52Ti0.48) O3 – BiFeO3 (PZT - BFO) multilayer thin film deposited on silicon substrate for possible application in future micro-electro-mechanical system (MEMS) devices. The PZT - BFO multilayer thin film is deposited on silicon wafer by sol-gel technique. The multilayer film is annealed a...

This paper discussed about the progressive microplasma generation in planar spiral inter-digitated terminal (IDT) structure. The IDT structures (with separation between two adjacent spiral electrodes varied progressively from 30 to 33 µm) are fabricated on quartz wafer by 5 µm thick gold electroplating. The onset of microplasma is witnessed around...

This paper reports growth of Co0.6Zn0.4Mn0.3Fe1.7O4 (CZFMO) ultrathin films (thickness: 23–30 nm) by spin coating technique on silicon (100), (110) and (111) substrates. The deposited films were annealed at 700 °C for 1 h in the oxygen environment. All the films were found to be polycrystalline in nature. The CZFMO films were found to have minimal...

This work presents optical properties of Zn and Mn co-doped CFO (Co0.6Zn0.4Mn0.3Fe1.7O4) films deposited on Si and Pt coated Si substrates by spin coating technique. X-ray diffraction pattern of the films exhibited spinel cubic structure with polycrystalline phase. Optical characteristics of the CZFMO films are studied using photoluminscence and UV...

This paper reports about the effect of fabrication process induced changes on scattering parameters of RF MEMS switch structure with meander geometry for 18–40 GHz (Ka-band) application. The designed structure showed a return loss better than 15 dB with a maximum isolation of 43 dB at 35 GHz. From the parametric analysis, both the return loss and i...

This paper reports on the comparison of residual stresses in AlN thin films sputter-deposited in identical conditions on Si (100) (110) and (111) substrates. The deposited films are of polycrystalline wurtzite structure with preferred orientation along the (002) direction. AlN film on the Si (111) substrate showed a vertical columnar structure, whe...

Integration of ferrite thin films of CoFe2O4 with silicon was an essential step for the development of magnetic and microwave micro-electro-mechanical system (MEMS) devices. This paper reports about the integration of Zn and Mn co-doped CoFe2O4 (Co0.6Zn0.4Fe1.7Mn0.3O4) thin films on silicon wafer surface. The films were deposited by spin coating te...

This paper presents growth and optical properties of nano-textured (110) Pb (Zr0.52Ti0.48)O3/(001) ZnO hetero-structure deposited on oxidized silicon substrate by RF sputtering technique. The X-ray diffraction analysis confirms the textured growth of the ZnO and PZT thin films. The grain sizes of ZnO and PZT films are found to be around 80 and 30 n...

This paper discusses about improved design for microplasma generation using a planar interdigitated terminal (IDT) structure. The IDT structure is fabricated by Au electroplating (5 µm) using a single mask process on quartz wafer. The gap between the subsequent IDT fingers is kept at 30 µm. The IDT structure showed microplasma generation at 570–580...

Metal oxide based hetero-structures (like Pb (ZrxTi1-x) O3 - ZnO) can be used for wide variety of future sensors and electronic devices. This paper presents growth and electrical properties of nano-textured (110) Pb (Zr0.52Ti0.48) O3/ (001) ZnO hetrostructure on oxidized silicon substrate by RF sputtering technique. The grain sizes of ZnO and PZT f...

This paper presents growth of TiO2-Cr2O3 nanocomposite ultrathin films (∼30 nm thick) by sputtering technique for gas sensor applications. The deposited films were annealed to grow rutile TiO2 and eskolaite Cr2O3 phases. Grain sizes of the pristine Cr2O3 and TiO2 films (45–50 nm) were found to be larger compared to the nano-composite (7.1–69.5% Cr2...

This paper reports about single phase Ni-substituted (0-20 at%) BiFeO3 (BFO) thin films for future optoelectronic device applications. The effect of Ni substitution on the microstructure, ferroelectric and optical properties of spin-coated BFO thin films were investigated. The x-ray diffractionpeaks corresponding to the (012) and (110) planes were...

Aluminium nitride (AlN) thin films are being extensively used for diverse applications. However, its use significantly depends on the minimization residual stress generated during the deposition process. This paper reports the evolution of residual stress in sputter deposited AlN thin films on Si (100) substrates with varying thickness. The deposit...

MEMS based accelerometers have already penetrated defense programs including navigation control in addition to their usual deployment in automotive, consumer and industrial markets because of their improved reliability, accuracy and excellent price performance. This paper discussed about the fabrication and testing of single axis capacitive acceler...

Molybdenum-di-sulfide (MoS2) is being considered as an alternative 2-D material to graphene. Deposition of ultrathin MoS2 layer from bulk MoS2 sample is an important criterion in determining the viability of its application. This paper discusses about growth and characterization of bulk MoS2 pellet from MoS2 powder and exfoliation of MoS2 layer fro...

Deep boron diffusion often induces residual stress in bulk micromachined MEMS structures, which may affect the MEMS devices operation. In this study, we studied the modal patterns of MEMS vibratory gyroscope under the residual stress (100 – 1000 MPa). Modal patterns and modal frequencies of the gyro are found to be dependent on the residual stress...

MEMS based vector hydrophone is being one of the key device in the underwater communications. In this paper, we presented a bio-inspired MEMS vector hydrophone. The hydrophone structure consists of a proof mass suspended by four meander type beams with reduced cross-section. Modal patterns of the structure were studied. First three modal frequencie...

Deep boron diffusion often induces residual stress in bulk micromachined MEMS structures, which may affect the MEMS devices operation. In this study, we studied the modal patterns of MEMS vibratory gyroscope under the residual stress (100 – 1000 MPa). Modal patterns and modal frequencies of the gyro are found to be dependent on the residual stress...

This paper presents deep boron diffusion induced damages in silicon (100), (110) and (111) surfaces. The silicon (100) and (110) samples showed a broad hump at the higher angle (ω) side during x-ray Rocking curve measurement; whereas, the (111) sample shows an additional broad peak at higher angle side. All the diffused samples showed two distinct...

This paper reports magnetic and magneto-optical properties of Co0.6Zn0.4Fe1.7Mn0.3O4 nanocrystalline thin films (thickness ∼140–200 nm) deposited on Pt (1 1 1)/Ti/SiO2/Si substrates by spin coating technique. Deposited films are then annealed at 600 °C and 700 °C for 60 min (significant reduction in film thickness from 200 nm to 140 nm was noted wi...

This paper discussed about radio frequency design of coplanar-waveguide (CPW) based π-matched shunt switch for broad-band (18-40 GHz) application. The effects of variation in membrane width (50 – 80 μm) of the switch and high-impedance transmission line length (200 – 600 μm) between the switch structures on scattering parameters are studied. The va...

Benzocyclobutene (BCB) is widely used for wafer level packaging of radio frequency micro-electro-mechanical system (RF MEMS) devices. Although BCB is spin-coated at room temperature, its prebaking, post baking and subsequent processing may induce residual stresses. This work intends to investigate the stress–temperature behaviour of BCB films. In t...