3 research outputs found
200-mm Si CMOS Process-Compatible Integrated Passive Device Stack for Millimeter-Wave Monolithic 3-D Integration
No full textIn this article, we have demonstrated a simple 200-mm Si CMOS process-based integrated passive device (IPD) stack for millimeter-wave (mmW) monolithic 3-D (M3D) integration. By developing a double chemical mechanical polishing (CMP) technique for the final intermetal dielectric (IMD) process, an rms value of less than 1 nm for the top-surface roughness of the IPD stack was achieved, resulting in uniform 3-D integration of a 100-nm-thick active layer of the InGaAs high-electron-mobility transistor (HEMT) on the stack. The stack included a trap-rich layer (TRL) and a buried oxide layer (BOX) with a high-resistance Si substrate (HRS) to achieve high-frequency properties. The TRL and BOX were optimized to keep wafer bowing as low as possible while minimizing the radio frequency (RF) loss. A fabricated coplanar waveguide (CPW) based on a TRL with poly-Si deposited by low-pressure chemical vapor deposition (LP-CVD) and a BOX with SiO deposited by LP-CVD exhibited an insertion loss (IL) value of 0.77 dB/mm at 40 GHz. IL values of the developed CPW were comparable to those of CMOS foundries, despite using thinner metal thickness, under a condition of the same metal width. The fabricated passive devices showed good quality factor (Q) characteristics sufficient to be utilized up to the V-band. In particular, the maximum Q values of the inductors are the best among Si lumped inductors reported in the mmW bands to date.
Implementation of Flip-Chip Microbump Bonding between InP and SiC Substrates for Millimeter-Wave Applications
No full textFlip-chip microbump (μ-bump) bonding technology between indium phosphide (InP) and silicon carbide (SiC) substrates for a millimeter-wave (mmW) wireless communication application is demonstrated. The proposed process of flip-chip μ-bump bonding to achieve high-yield performance utilizes a SiO(2)-based dielectric passivation process, a sputtering-based pad metallization process, an electroplating (EP) bump process enabling a flat-top μ-bump shape, a dicing process without the peeling of the dielectric layer, and a SnAg-to-Au solder bonding process. By using the bonding process, 10 mm long InP-to-SiC coplanar waveguide (CPW) lines with 10 daisy chains interconnected with a hundred μ-bumps are fabricated. All twelve InP-to-SiC CPW lines placed on two samples, one of which has an area of approximately 11 × 10 mm(2), show uniform performance with insertion loss deviation within ±10% along with an average insertion loss of 0.25 dB/mm, while achieving return losses of more than 15 dB at a frequency of 30 GHz, which are comparable to insertion loss values of previously reported conventional CPW lines. In addition, an InP-to-SiC resonant tunneling diode device is fabricated for the first time and its DC and RF characteristics are investigated
Demonstration of CMOS-compatible memristor-based electrochemical biosensor transducer with threshold-sensing functionality
No full textMany electrochemical biosensors operate based on a threshold-sensing (TS) method, which indicates the presence of a disease when the concentration of a biomarker exceeds a predetermined, disease-specific threshold. The TS in biosensor systems is often implemented using power-hungry signal processing (SP) modules or computers, which increases energy consumption and system complexity. Here, we propose a memristor-based bio-to-electrical transducer with built-in TS functionality, allowing TS to be performed directly within the transducer instead of relying on SP modules and computers. Fabricated resistive random-access memory-based TaOX/Ta2O5 memristors meet the transducer requirements, such as a high on/off ratio greater than 30 while maintaining a long unit pulse width exceeding 10 mu s. The intended operation of the proposed transducer was experimentally confirmed by the immediate change in resistance of the memristor (RM) from high resistance state to low resistance state. Using this proposed transducer, a complete electrochemical biosensor system was implemented by integrating a sensor electrode for pH sensing, an SP module, and a display with the proposed transducer. The memristor-based system offers flexible control of the threshold pH point through a simple design, making it well-suited for point-of-care diagnostics, where portability is highly essential.
