Negative differential resistance (NDR), where the device current decreases with increasing bias voltage, is a representative phenomenon where quantum mechanics induces counterintuitive physical behavior and offers promising applications such as high-frequency oscillators, amplifiers, and multilevel logic circuits. While the NDR behavior has been extensively studied in various materials and devices, the role of surface properties in NDR, particularly in InAs-based diodes, remains underexplored. In this work, we report the observation of NDR in vertically structured InAs p+n diodes that exhibit a peak-valley current ratio of ∼6, which is suitably high for applications. Circumference-normalized current–voltage characterization revealed that the NDR originates from band-to-band tunneling between the valence band of p+-InAs and the conduction band of an n+-InAs surface, where the n+ surface is due to surface states on otherwise n−-InAs. In addition, by comparing devices with various surface passivation methods (without intentional passivation, benzocyclobutene polymer, and silicon nitride), we found that the surface termination significantly affects the NDR characteristics. We present an equivalent circuit model to explain the observed device behavior. These findings offer insights into surface-enabled NDR phenomena and present new knobs for engineering NDR devices.

This paper presents a compact on-chip multiple-input multiple-output (MIMO) antenna designed for future communication systems, featuring frequency-agile elements. The antenna achieves enhanced decoupling and reduced cross-section through the integration of a metasurface, which also introduces frequency agility. Designed for the millimeter-wave band using low-loss BenzoCycloButene (BCB) polymer, the antenna is manufactured with microelectronic processes, and the dimensions are 7.54 × 7.54 × 0.055 mm3. Simulations and measurements demonstrate excellent frequency agility around 60 GHz, with gains of 6.5 to 9 dBi. As a proof of concept, open and short circuits were used for switching, with future designs aiming to incorporate diodes for a full dynamic reconfiguration. This work highlights the potential for compact, high-performance, and frequency-reconfigurable on-chip antennas in next-generation millimeter-wave systems.

The integrated THz pattern over any MMIC appears to be a good opportunity to enclose calibration kit suitable for accurate measurements. An original technology based on polymer has been developed. Sub-millimeter single-mode conductor-backed coplanar waveguides using benzocyclobutene polymer and interconnecting via between ground planes are processed and measured up to 760 GHz. The experimental performances show good agreement with analytical and numerical modeling. A two-tier Thru-Reflect-Line correction and a square root of Thru de-embedding are applied to extract the attenuation factor of about 3 dB/mm at 600 GHz, the relative phase velocity to light of about 0.716 and the characteristic impedance around 50 Ω. The fundamental propagating mode remains unique in this wide frequency range, enabling this technological to be integrated over existing circuit for THz applications. The loss performance of the coplanar waveguide ranges in the state-of-the-art opening the road for fully integrated THz circuits.

Solar cells with undoped PCBCB:CL extraction layers exhibit higher power conversion efficiencies than their PCBM and PCBCB counterparts, as well as excellent thermal stability.

Multi-chip Module (MCM) is a technology that can be applied to silicon and alumina modules allowing advantages in the integration complexity. This paper reports a MCM-D (D for deposition) technology suitable to fabricate passive components using two metal levels and non-photosensitive polymer benzocyclobutene as dielectric. The devices are produced using thin film technology, vacuum metallization, electroless and electrolytic deposition, photolithography process and wet etching. Electrical measurements and focused ion beam (FIB) were used to evaluate the characteristics of the MCM-D structures.

Single crystalline lithium niobate (LN) thin films with a Y43-cut are fabricated by crystal-ion-slicing technique, and the B-staged benzocyclobutene (BCB) polymer is used as the bonding medium for the transferring of the LN thin film on to a homogeneous LN substrate. The thickness of the LN film is about 910 nm, and low energy ion irradiation is used to treat the surface of the film, which reduces the roughness from 12.4 nm down to 3.6 nm. Bulk acoustic wave (BAW) resonator is fabricated based on the thin LN layer, and the electromechanical coefficient (k2t) of the LN film reaches 16.3%. A 3-stage BAW filter is obtained, and the 3 dB bandwidth of the filter is 8.5%, demonstrating the single crystalline LN thin film with large k2t is promising for wide band filter.

Abstract In this paper, a copper/benzocyclotene thin film based microstrip bandpass filter featured by a thick dielectric layer is presented. For thickening dielectric layer, a 30 μm‐deep micromachined groove with embedded benzocyclotene polymer is fabricated on the surface of silicon substrate. Mechanical polishing is utilized to planarize the benzocyclotene polymer embedded in the groove. Atomic Force Microscopy is used to characterize the surface roughness of benzocyclobutene (BCB) polymer film before and after polishing. With two additional BCB layer, a total thickness of 75.4 μm dielectric layer is realized, and the insertion loss of the filter can be reduced by 1.34 dB theoretically. The measured insertion loss of fabricated filter is −2.2 dB, which can be further reduced via tighter control of device parameters.

Interfacial adhesion between metallic thin films and polymers is a critical performance metric for a number of microelectronics and packaging applications. Delamination of metal-polymer interfaces is a frequent failure mode for many multilayer structures, like those used for electronics packaging. Such a failure is even more likely when electronic packages are operated under extreme conditions like high-power, high-temperature, and/or high-humidity operation. Roughening or direct chemical modification of the few layers of atoms that make up the interface is often used to promote adhesion at these interfaces. Here, the authors investigate a new process, vapor phase infiltration, that infiltrates inorganic constituents into the bulk of the polymer, creating an interpenetrating network within the subsurface of the polymer that further enhances interfacial adhesion. For the authors’ model system of copper films on a benzocyclobutene polymer, they are able to increase the interfacial adhesion strength by as much as 3×, resulting in cohesive rather than adhesive failure. The authors attribute this increased interfacial adhesion to physicochemical interlocking of the organic and inorganic phases within the subsurface of the polymer, generating a “root system” that impedes interfacial delamination.

We present a low-temperature processing scheme for the integration of either lateral or vertical nanowire (NW) transistors with a multilayer back-end-of-line interconnect stack. The nanowire device temperature budget has been addressed, and materials for the interconnect fabrication have been selected accordingly. A benzocyclobutene (BCB) polymer is used as an interlayer dielectric, with interconnect vias formed by reactive ion etching. A study on via etching conditions for multiple interlayer dielectric thicknesses reveals that the sidewall slope can be engineered. An optimal reactive ion etch is identified at 250 mTorr chamber pressure and power of 160 W, using an SF6 to O2 gas mix of 4%. This results in a low via resistance, even for scaled structures. The BCB dielectric etch rate and dielectric-to-soft mask etch selectivity are quantified. Electrical measurements on lateral and vertical III-V NW transistors, before and after the back-end-of-line process, are presented. No performance degradation is observed, only minor differences that are attributed to contact annealing and threshold voltage shift.

In this letter, a compact self-packaged folded substrate-integrated waveguide filter with loaded stubs is presented. Transmission zeros (TZs) at the same number of filter order are designed to improve out-of-band performance. The position of each TZ is controlled independently. The first spurious resonance increases by up to 3.8 times the fundamental frequency by suppressing the original first parasitic resonance. A Ka -band filter with a benzocyclobutene (BCB) polymer as a dielectric is fabricated and measured to verify the design concept.

This study designs a micro‐machined BCB‐cavity patch antenna and two types of four‐element micro‐machined antenna arrays at 100 GHz. The patches are fabricated on Benzocyclobutene (BCB) polymer material. The silicon substrate is selective lateral etched under the patch antenna to fabricate a cavity surrounded by metal and filled with BCB material. The BCB‐cavity under patches can reduce the excitation of surface waves and enhance the radiation on performance. A single large BCB‐cavity is designed to implement the four‐element antenna arrays under the consideration of mutual coupling. The proposed single antenna has a 2.8 GHz impedance bandwidth. At 100 GHz, the simulated maximum gain is 6.7 dBi for the single antenna and 13 dBi for the four‐element antenna arrays.

A silicon-based phased-array transmitter working at 100 GHz is proposed in this study. Planar array ferroelectric film phase shifters (FPSs) are realised with patch antennas, DC bias lines, microstrip lines and power dividers on a monolithic silicon substrate. The system enables full process compatibility and avoids loss caused by multichip interconnection. The isolation layer uses benzocyclobutene polymer film with low permittivity and low loss tangent, providing large thickness physical isolation. The FPS has a compact length of 0.45 mm, and simulation results show that its phase shift degree at 100 GHz is 125.7° with 3.95 dB insertion loss and 11.4 dB reflection loss. The patch antenna shows that the maximum simulated radiation gain of the single antenna is 4 dBi and the four-element antenna array is 9.7 dBi at 100 GHz. The beam can be steered to ±10°. The proposed system lays an important foundation for the realisation of silicon-based system-on-chip radar RF front-end system.

In this paper, this research is after the process CMOS driver substrate. It is the use of A Benzocyclobutene polymer thin films planarization coating material in elements of the LED array manufacturing process. This CMOS driver circuit is a mode architecture that uses serial input data and parallel output data. It is the use of shift registers and latch circuit cell to form the overall system chip. The current density of the microcrystalline LED elements of each size is the same condition. The current density of a single 16 μm microcrystalline LED pixel driven by a 2.85 V drive circuit board is about 2.69 μA.

Covering a whole surface of a robot with tiny sensors which can measure local pressure and transmit the data through a network is an ideal solution to give an artificial skin to robots to improve a capability of action and safety. The crucial technological barrier is to package force sensor and communication function in a small volume. In this paper, we propose the novel device structure based on a wafer bonding technology to integrate and package capacitive force sensor using silicon diaphragm and an integrated circuit separately manufactured. Unique fabrication processes are developed, such as the feed-through forming using a dicing process, a planarization of the Benzocyclobutene (BCB) polymer filled in the feed-through and a wafer bonding to stack silicon diaphragm onto ASIC (application specific integrated circuit) wafer. The ASIC used in this paper has a capacitance measurement circuit and a digital communication interface mimicking a tactile receptor of a human. We successfully integrated the force sensor and the ASIC into a mm die and confirmed autonomously transmitted packets which contain digital sensing data with the linear force sensitivity of 57,640 Hz/N and 10 mN of data fluctuation. A small stray capacitance of 1.33 pF is achieved by use of 10 m thick BCB isolation layer and this minimum package structure.

A radio-frequency micro-electro-mechanical system (RF MEMS) wafer-level packaging (WLP) method using pre-patterned benzo-cyclo-butene (BCB) polymers with a high-resistivity silicon cap is proposed to achieve high bonding quality and excellent RF performance. In this process, the BCB polymer was pre-defined to form the sealing ring and bonding layer by the spin-coating and patterning of photosensitive BCB before the cavity formation. During anisotropic wet etching of the silicon wafer to generate the housing cavity, the BCB sealing ring was protected by a sputtered Cr/Au (chromium/gold) layer. The average measured thickness of the BCB layer was 5.9 μm. In contrast to the conventional methods of spin-coating BCB after fabricating cavities, the pre-patterned BCB method presented BCB bonding layers with better quality on severe topography surfaces in terms of increased uniformity of thickness and better surface flatness. The observation of the bonded layer showed that no void or gap formed on the protruding coplanar waveguide (CPW) lines. A shear strength test was experimentally implemented as a function of the BCB widths in the range of 100–400 μm. The average shear strength of the packaged device was higher than 21.58 MPa. A RF MEMS switch was successfully packaged using this process with a negligible impact on the microwave characteristics and a significant improvement in the lifetime from below 10 million to over 1 billion. The measured insertion loss of the packaged RF MEMS switch was 0.779 dB and the insertion loss deterioration caused by the package structure was less than 0.2 dB at 30 GHz.

Enhancing the magnetoelectric coupling in a strain-mediated multiferroic composite structure plays a vital role in controlling magnetism by electric fields. An enhancement of magnetoelastic coupling between ferroelectric single crystal (011)-cut [Pb(Mg1/3Nb2/3)O3](1-x)-[PbTiO3]x (PMN-PT, x≈ 0.30) and ferromagnetic polycrystalline Ni thin film through an interposed benzocyclobutene polymer thin film is reported. A nearly twofold increase in sensitivity of remanent magnetization in the Ni thin film to an applied electric field is observed. This observation suggests a viable method of improving the magnetoelectric response in these composite multiferroic systems.

This paper presents design, fabrication, and high-frequency characterization of through-silicon-vias (TSVs) with benzocyclobutene (BCB) as the dielectric liner to exploit its low dielectric constant. Fabrication processes for BCB polymer liner TSVs are developed, and BCB-liner TSVs have been successfully fabricated in both low-resistivity silicon and high-resistivity silicon substrates for comparison. A de-embedding method that enables extraction of S-parameters from cascade TSV chains is developed based on the thru-reflect-line calibration algorithm, and the S-parameters of BCB-liner TSVs have been obtained from the measured transmission properties of cascade TSV chains with frequencies up to 25 GHz. Measurement results show that the BCB liner improves transmission properties of TSVs up to 10 GHz compared with SiO2-liner TSVs, and sub-strate resistivity dominates transmission properties for frequencies higher than 10 GHz.

A large performance improvement of polymer phase modulators is reported by using buried in-plane coupled microstrip (CMS) driving electrodes, instead of standard vertical Micro-Strip electrodes. The in-plane CMS driving electrodes have both low radio frequency (RF) losses and high overlap integral between optical and RF waves compared to the vertical designs. Since the optical waveguide and CMS electrodes are located in the same plane, optical injection and microwave driving access cannot be separated perpendicularly without intersection between them. A via-less transition between grounded coplanar waveguide access and CMS driving electrodes is introduced in order to provide broadband excitation of optical phase modulators and avoid the intersection of the optical core and the electrical probe. Simulation and measurement results of the benzocyclobutene polymer as a cladding material and the PMMI-CPO1 polymer as an optical core with an electro-optic coefficient of 70 pm/V demonstrate a broadband operation of 67 GHz using travelling-wave driving electrodes with a half-wave voltage of 4.5 V, while satisfying its low RF losses and high overlap integral between optical and RF waves of in-plane CMS electrodes.

2×2 parallel fed and 3×3 serial fed patch antenna arrays on a benzocyclobutene (BCB) polymer layer are integrated with a 70 μm wide, dry etched, double metal waveguide quantum cascade laser, operating at about 1.9 THz. The BCB surrounds the quantum cascade laser ridge and is planarized to fit precisely its height. The patch antenna arrays emit a linearly polarized, highly symmetric beam perpendicular to the antenna plane. The beams have a FWHM angle of 49° (2×2) and 35° (3×3). Both measurements and simulations indicate coupling factors to a Gaussian beam of over 90%. The antenna design is strongly governed by the high thickness (h=13.6 μm) and the low dielectric constant (ϵr=2.45) of the BCB substrate. Because the patch array has a very low input reflectivity of -13 to -20 dB over the 1.7-2.1 THz operation band, the laser needs a partially transmitting reflector to maintain the Q-factor of the active medium resonator to assure lasing in the antennas operation band. By changing the dimensions of the reflector, the facet transparency can be designed in a wide range from fully transmissive to highly reflective.

Broadband transitions are presented in this paper for capacitively grounded coplanar waveguide to coupled microstrip (CMS) lines. These transitions are realized on both thick Rogers RO3003 substrate (thickness of 10 mils) and a thin benzocyclobutene (BCB) polymer film (thickness of 20 µm). A flat bandwidth of 4–20 GHz and 3.2 to over 40 GHz are measured for the RO3003 and BCB polymer substrates, respectively. These performances are obtained without making via-hole in the substrate or patterning the bottom ground plane, which makes this broadband transition easier to fabricate compared with the via-hole-based grounded CPW–CMS transitions.