Robust porous SiOCH/Cu interconnects with ultrathin sidewall protection liners

Robust porous low-k/Cu interconnects have been developed for 65-nm-node ultralarge-scale integrations (ULSIs) with 180-nm/200-nm pitched lines and 100-nm diameter vias in a single damascene architecture. A porous plasma-enhanced chemical vapor deposition (PECVD)-SiOCH film (k=2.6) with subnanometer pores is introduced into the intermetal dielectrics on the interlayer dielectrics of a rigid PECVD-SiOCH film (k=2.9). This porous-on-rigid hybrid SiOCH structure achieves a 35% reduction in interline capacitance per grid in the 65-nm-node interconnect compared to that in a 90-nm-node interconnect with a fully rigid SiOCH. A via resistance of 9.7 /spl Omega/ was obtained in 100-nm diameter vias. Interconnect reliability, such as electromigration, and stress-induced voiding were retained with interface modification technologies. One of the key breakthroughs was a special liner technique to maintain dielectric reliability between the narrow-pitched lines. The porous surface on the trench-etched sidewall was covered with an ultrathin plasma-polymerized benzocyclobuten liner (k=2.7), thus enhancing interline time-dependent dielectric breakdown reliability. The introduction of a porous material and the control of the sidewall are essential for 65-nm-node and beyond scaled-down ULSIs to ensure high levels of reliability.     

GaInNAs-GaAs long-wavelength vertical-cavity surface-emitting laserdiodes

Vertical-cavity surface-emitting laser diodes with GaInNAs-GaAs quantum-well (QW) active layers are demonstrated for the first time. GaInNAs permits the realization of a long-wavelength vertical-cavity laser grown directly on a GaAs substrate. Room-temperature (RT) pulsed operation is achieved, with an active wavelength near 1.18 μm, threshold current density of 3.1 kA/cm², slope efficiency of ~0.04 W/A, and output power above 5 mW for 45-μm-diameter devices. Laser oscillation is observed for temperatures at high as 95°C     

Highly nondegenerate four-wave mixing among subpicosecond opticalpulses in a semiconductor optical amplifier

We have demonstrated, for the first time, the highly nondegenerate four-wave mixing (FWM) among subpicosecond optical pulses in a 1.3-μm multiple-quantum-well (MQW) semiconductor optical amplifier (SOA). We could directly measure the FWM signal in the output spectrum by current pulse pumping of the device. We achieved a high conversion efficiency of over 10% at a frequency conversion range of less than 1 THz. The limitation of conversion efficiency due to the gain saturation of the SOA was effectively overcome by using the short optical pulses     

A new cobalt salicide technology for 0.15-μm CMOS devices

A new cobalt (Co) salicide technology for sub-quarter micron CMOS transistors has been developed using high-temperature sputtering and in situ vacuum annealing. Sheet resistance of 11 Ω/□ for both gate electrode and diffusion layer was obtained with 5-nm-thick Co film. No line width dependence of sheet resistance was observed down to 0.15-μm-wide gate electrode and 0.33-μm-wide diffusion layer. The high temperature sputtering process led to the growth of epitaxial CoSi ₂ layers with high thermal stability. By using this technology 0.15 μm CMOS devices which have shallow junctions were successfully fabricated     

Blue electroluminescent devices withSrGa2S4:Ce for full-color display

In order to realize full-color electroluminescent (EL) displays, which are expected as a dominant candidate for the future multimedia flat panel display, blue EL devices with SrGa₂S₄:Ce have been prepared by molecular beam epitaxy (MBE). This paper proposes a novel deposition method employing Sr metal and Ga₂S₄ compound as the source materials. A single-phase SrGa₂S₄ layer is obtained in a Ga₂S₃/Sr flux ratio of 60 and at the growth temperature of 560°C. We have obtained the well-saturated blue with CIE color coordinates of x=0.14, y=0.14 and brighter blue EL devices made by optimizing the growth conditions in MBE. The maximum luminance of 70 cd/m² in comparison with the 3 cd/m₂ of our previous EL devices, is achieved at a driving frequency of 1 kHz     

Optical filtering to reduce chirping influence in LD wavelength conversion

The use of an optical filter to reduce chirping influence in LD wavelength conversion is demonstrated. A part of broadened spectrum of wavelength-converted light is eliminated by a narrow-band optical filter, and sensitivity degradation due to frequency chirping is reduced as a result. In an experiment using a fiber Fabry-Perot filter, the sensitivity was improved by about 1.5 dB in 1.55-/spl mu/m transmissions with normal dispersion fibers when an LD converter was biased at two times the threshold current.     

Noise transfer characteristics in wavelength conversion based on cross-gain saturation in a semiconductor optical amplifier

Wavelength conversion based on cross-gain saturation in a semiconductor optical amplifier is studied from the viewpoint of how fluctuation in the input signal is transferred to the converted signal. Experiments in which a signal light with amplifier ASE noise is converted show that fluctuation in the "on"-level is suppressed while fluctuation in the "off"-level is enhanced due to the in/out relation of the converter.     

Semi-transparent PV: Thermal performance, power generation, daylight modelling and energy saving potential in a residential application

In this research, semi-transparent PV is proposed as top light material for residential application. Using the results of field measurements, essential parameters pertaining to the power generation, thermal and optical characteristics of semi-transparent PV panels are understood. Calculation models presenting the above characteristics are developed and validated. The validated models are incorporated into Energy Plus to carry out overall energy consumption analyses in five climate regions in Japan to assess the energy saving potential of the semi-transparent PV panels. With appropriate optimization measures, the semi-transparent PV top light with 50% radiation transmission rate contributes to a maximum of 5.3% reduction in heating and cooling energy consumption compared with a standard BiPV roof. The effect of daylighting in lighting energy saving is subtle as most of the residential lighting demand occur during night-time. In the aspect of total energy consumption, net energy savings in the range of 3.0–8.7% are achieved for the 50% radiation transmission semi-transparent PV top light case relative to the base case of BiPV roof, where reduction in heating and cooling energy demand contributes most to the total energy saving.     

Single-grain Si thin-film transistors SPICE model,analog and RF circuit applications

Single-grain thin-film transistors (SG-TFTs) fabricated inside location-controlled using μ-Czochralski process exhibit SOI-FETs like performance despite processing temperatures remaining below 350 °C. Thus, the SG-TFT is a potential technology for large-area highly-integrated electronic system and system-in-package, taking advantage of the system-on-flexible substrate and low manufacturing cost capabalities. The SG-TFT is modeled based on the BSIMSOI SPICE model where the mobility parameter is modified to fit the SG-TFT behavior. Therefore, analog and RF circuits can be designed and benchmarked. A two-stage telescopic cascode operational amplifier fabricated in a prototype 1.5 μm SG-TFT technology demonstrates DC gain of 55 dB and unity-gain bandwidth of 6.3 MHz. A prototype CMOS voltage reference demonstrates a power supply rejection ratio (PSRR) of 50 dB. With unity-gain frequency, f_T, in the GHz range, the SG-TFT can also enable RF circuits for wireless applications. A 12 dB gain RF cascode amplifier with integrated on-chip inductors operating in the 433 MHz ISM band is demonstrated.     

自组织InAs/GaAs量子点的表面氮化研究

用低温光荧光(PL)和透射电子显微镜(TEM)研究了表面氮化自组织InAs/GaAs量子点的光学性能和微观结构。结果表明氮化后形成薄层的InAsN薄膜作为应变缓和层覆盖在量子点的表面,使得随着氮化时间的增加,InAs量子点的位错密度提高、尺寸变大、纵横比提高、发光波长变长、强度变低。