Low-k Benzocyclobutene Research Articles

A Bis-Stabilized Interface Strategy for Low-k Benzocyclobutene-Based Hollow Silica Nanocomposites

A bis-stabilized interface strategy has been proposed to prepare high-performance low-dielectric (low-k) benzocyclobutene (BCB)-based nanocomposites by a rational-designed and facile-synthesized difunctional silane modifier. Hollow silica nanoparticles (HSNs) can be efficiently surface-modified with the difunctional silane to be evenly dispersed and chemically cross-linked with the BCB resin matrix during the post-thermal curing process, finally obtaining a series of HSNs-doped organic–inorganic nanocomposites. The dielectric properties of the resultant nanocomposites can be effectively adjusted by changing the doping ratios and cavity diameters of HSNs. Compared with commercial BCB resin, the dielectric constant of resultant 0.25 wt % HSNs-doped nanocomposites with a cavity diameter of 180 nm can be greatly reduced to 2.12 by 20%, maintaining the low level (10–4 at 1 kHz) of the dielectric loss, excellent thermal stability, and hydrophobicity as well. This study provides a facile and universal strategy to fabricate low-k BCB nanocomposites for future high-density advanced packaging applications.

采用BCB平整技术的高速850 nm垂直面发射激光器

Vertical-cavity surface-emitting lasers(VCSELs) are widely used in short-reached optical interconnects and data communication links because of their low energy consumption and high modulation speed. Capacitance, as the parasitic parameters, affects the modulation bandwidth. In this paper, parasitic capacitance of VCSELs is reduced by using a low-k benzocyclobutene(BCB) planarization technique. The detail BCB planarization technique has been discussed with optimal process parameters, which is useful for high-speed VCSEL fabrication. The small signal modulation bandwidth of the low-k BCB planarization VCSEL with 7 μm oxide aperture has been achieved to 15.2 GHz.

High-performance intrinsic low-k polymer via the synergistic effect of its three units: adamantyl, perfluorocyclobutylidene and benzocyclobutene

Intrinsic highly cross-linked low-k benzocyclobutene polymer functionalized with adamantyl and perfluorocyclobutylidene.

Design, Fabrication, and Characterization of a Rotary Micromotor Supported on Microball Bearings

We report the design, fabrication, and characterization of a rotary micromotor supported on microball bearings. This is the first demonstration of a rotary micromachine with a robust mechanical support provided by microball-bearing technology. A six-phase bottom-drive variable-capacitance micromotor (Phi = 14 mm) is designed and simulated using the finite-element (FE) method. The stator and the rotor are fabricated separately on silicon substrates and assembled with the microballs. Three layers of low-k benzocyclobutene polymer, two layers of gold, and a silicon microball housing are fabricated on the stator. Microball housing and salient structures (poles) are etched in the rotor and are coated with a silicon carbide film that reduces the friction without which the operation was not possible. A top angular velocity of 517 r/min, corresponding to the linear tip velocity of 324 mm/s, is measured at plusmn150-V and 800-Hz excitation. This is 44 times higher than the velocity previously demonstrated for linear micromotors supported on the microball bearings. A noncontact method is developed to extract the torque and the bearing coefficient of friction through dynamic response measurements. The torque is indirectly measured to be -5.62 plusmn 0.5 muN ldr m at plusmn150-V excitation which is comparable with the FE simulation results predicting -6.75 muN ldr m. The maximum output mechanical power at plusmn150 V and 517 r/min was calculated to be 307 muW. The bearing coefficient of friction is measured to be 0.02 plusmn 0.002 which is in good agreement with the previously reported values. The rotary micromotor developed in this paper is a platform technology for centrifugal micropumps used for fuel-delivery and cooling applications.

Hot-Electron-Induced Degradation in BCB- and SiN-Passivated $\hbox{Al}_{0.25}\hbox{Ga}_{0.75}\hbox{As/In}_{0.2}\hbox{Ga}_{0.8}\hbox{As}$ PHEMTs

In this paper, the hot-electron-induced degradation in Al0.25Ga0.75As/In0.2Ga0.8As pseudomorphic high-electron-mobility transistors passivated by low-k benzocyclobutene (BCB) has been investigated. Compared to the more commonly used silicon nitride (SiN), BCB has a lower dielectric constant and loss tangent and is becoming popular for passivation. However, its influence on the device hot-electron reliability has not been extensively studied so far. This paper examines the changes in the device dc drain-current, transconductance, and OFF-state breakdown voltages before and after hot-electron stress. For comparison purposes, the results for a device passivated using SiN have been included. The dominant mechanism that is responsible for the degradation in each technology has also been proposed and explained.

Investigation of drain current transient in BCB- and SiN-passivated Al0.25Ga0.75As∕In0.2Ga0.8As pseudomorphic high electron mobility transistors

The authors report on the drain current transient of Al0.25Ga0.75As∕In0.2Ga0.8As pseudomorphic high electron mobility transistors passivated by low-k benzocyclobutene (BCB). Compared to the more commonly used silicon nitride, BCB has a lower dielectric constant and loss tangent and is becoming popular for passivation. However, its effect on the device drain current transient has not been studied so far. In this work, the effectiveness of BCB as a passivation material was investigated in relation to the device drain current transient response. The surface trap model was also used to describe the transient behavior quantitatively.

12.5-Gbps Operation of 850-nm Vertical-Cavity Surface-Emitting Lasers With Reduced Parasitic Capacitance by BCB Planarization Technique

12.5-Gbps operation of 850-nm AlGaAs-based VCSEL fabricated using low-k benzocyclobutene (BCB) planarization technique is reported. The BCB has lowest dielectric constant of 2.65 among conventional passivation dielectrics including polyimide and thick passivation can be easily formed by simple planarization technique, resulting in very low parasitic capacitance especially at around the pad electrode. The thick BCB film buried around the epitaxial post structure reduces the parasitic capacitance down to 0.041 pF which is one third as low as that of the conventional SiN passivated VCSELs. The fabricated BCB-planarized VCSEL exhibits very high relaxation oscillation frequency of 12 GHz for the oxide aperture of 6.5 /spl mu/m, which corresponds to high modulation bandwidth f/sub 3dB/ of 16 GHz with relaxation oscillation frequency of 11 GHz for the oxide aperture of 8.5 /spl mu/m. These values are as comparably high as the reported highest values. Open eye-diagrams up to 12.5 Gbps are also confirmed implying that the presented VCSEL is applicable to the optical data network systems such as Giga-bit Ethernet at higher bit rates. Preliminary reliability test result shows stable optical output power at constant operating current at 100 /spl deg/C over 1000 h.

Grating Metal Structure with Low-K Benzocyclobutene and Electroplated Copper for High-Q Spiral Inductors

In this paper, we propose a grating metal structure with low-K benzocyclobutene (BCB) and electroplated copper to increase the Q-factor of a spiral inductor. The grating metal structure was fabricated using simple electroplated copper and showed a maximum quality factor (Qmax) of 4 nH in spiral inductors, which is 15% more than that in normal spiral inductors with the same metal thickness. From the proposed equivalent lumped element model, the enhancement in quality factor was found to result from the reduction in series resistance, which was caused by the increase in effective current area. This technique can be applied to increasing the Q-factor of a spiral inductor in a silicon-based radio-frequency-integrated circuit (RFIC).

Electrical Characterization of Benzocyclobutene Polymers for Electric Micromachines

An approach using interdigitated capacitors for electrical characterization of CYCLOTENE, a spin-on low-k benzocyclobutene (BCB)-based polymer is introduced and the effect of moisture uptake is investigated. The dielectric constant of CYCLOTENE is extracted from capacitance measurements with a systematic error less than 0.1%, giving an average value of 2.49 with a standard deviation of 1.5%. The dielectric constant increases by 1.2% after a humidity stress of 85% RH at 85/spl deg/C. The I-V characteristics of CYCLOTENE show a dependency of breakdown strength and leakage current on the geometrical dimensions of the device under test. A breakdown strength of 225V//spl mu/m and 320 V//spl mu/m for 2-/spl mu/m and 3-/spl mu/m finger spacing, respectively, and a leakage current of a few to tens of pA are measured. The I-V characteristics degrade drastically after the humidity stress, showing a breakdown strength of 100 V//spl mu/m and 180 V//spl mu/m for 2-/spl mu/m and 3-/spl mu/m finger spacing, respectively, and a maximum increase in the leakage current as large as one order of magnitude. The maximum performance and long-term reliability of an electric micromachine are adversely affected by the degradation of the breakdown voltage and the leakage current after moisture absorption. It is expected, however, that the electrical efficiency is improved using BCB-based polymers with negligible dependency on moisture absorption.

Low‐loss microwave filters on CMOS‐grade standard silicon substrate with low‐k BCB dielectric

AbstractBenzocyclobutene (BCB), a low‐k, photosensitive, easily patterned material is used as the interfacing layer that isolates the passive components from the lossy, low‐resistivity silicon. Its performance is further improved by reducing the conductive loss with an electroplated and highly‐conductive metal, namely, copper. Standard 50‐Ω microstrip lines and a microstrip‐transmission‐line‐based microwave filter, exhibiting insertion losses of 0.8 dB and 1.1 dB at 10 GHz, respectively, are demonstrated. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 9–11, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11271

0.2-μm gate-length InGaP-InGaAs DCFETs for c-band MMIC amplifier applications

A C-band In/sub 0.49/Ga/sub 0.51/P-In/sub 0.15/Ga/sub 0.85/As doped-channel FET (DCFET) monolithic power amplifier was designed and fabricated using low-k benzocyclobutene (BCB) interlayer technology. With a photosensitive low-k BCB interlayer (/spl epsiv/=2.7), not only can the circuit's passivation layer, but also the capacitor insulator, via holes, and bridge process be realized simultaneously, where the process complexity and cost can be reduced. In addition, a 0.2-/spl mu/m T-shaped gate InGaP-InGaAs doped-channel FET with a high current density and a high linearity is introduced to the amplifier using the e-beam lithography. This C-band power amplifier can achieve a linear power gain of 9.3 dB and an output power of 15.3 dBm, which proves that this novel MMIC process using low-k BCB interlayer technology is attractive for microwave and millimeter wave circuit applications.

High performance BCB-bridged AlGaAs/InGaAs power HFETs

A novel low-k benzocyclobutene (BCB) bridged and passivated layer for AlGaAs/InGaAs doped-channel power field effect transistors (FETs) with high reliability and linearity has been developed and characterized. In this study, we applied a low-k BCB-bridged interlayer to replace the conventional air-bridged process and the SiN/sub x/ passivation technology of the 1 mm-wide power device fabrication. This novel and easy technique demonstrates a low power gain degradation under a high input power swing, and exhibits an improved adjacent channel power ratio (ACPR) than those of the air-bridged one, due to its lower gate leakage current. The power gain degradation ratio of BCB-bridged devices under a high input power operation (P/sub in/ = 5 /spl sim/ 10 dBm) is 0.51 dB/dBm, and this value is 0.65 dB/dBm of the conventional air-bridged device. Furthermore, this novel technology has been qualified by using the 85-85 industrial specification (temperature = 85 C, humidity = 85%) for 500 h. These results demonstrate a robust doped-channel HFET power device with a BCB passivation and bridged technology of future power device applications.

Silicon-based high-Q inductors incorporating electroplated copper and low-K BCB dielectric

We have fabricated high-Q copper inductors using low-K benzocyclobutene (BCB) dielectric as an interface layer on standard CMOS silicon substrate. Metal ohmic loss and substrate loss, the two major factors that degrade the Q-factors of on-chip inductors, are suppressed by the employment of electroplated copper and the BCB dielectric, respectively. The inductors exhibit Q-factors as high as 25 at 2 GHz. The dependence of inductor's high-frequency performance on inductor's parameters, such as BCB and copper thickness, has been investigated in detail. The inductor fabrication process is low-cost and low-temperature, making it suitable for post-IC process for high-performance RFICs and MMICs.