Kyoung-won Na

Organic-on-silicon complementary metal-oxide-semiconductor colour image sensors

Complementary metal–oxide–semiconductor (CMOS) colour image sensors are representative examples of light-detection devices. To achieve extremely high resolutions, the pixel sizes of the CMOS image sensors must be reduced to less than a micron, which in turn significantly limits the number of photons that can be captured by each pixel using silicon (Si)-based technology (i.e., this reduction in pixel size results in a loss of sensitivity). Here, we demonstrate a novel and efficient method of increasing the sensitivity and resolution of the CMOS image sensors by superposing an organic photodiode (OPD) onto a CMOS circuit with Si photodiodes, which consequently doubles the light-input surface area of each pixel. To realise this concept, we developed organic semiconductor materials with absorption properties selective to green light and successfully fabricated highly efficient green-light-sensitive OPDs without colour filters. We found that such a top light-receiving OPD, which is selective to specific green wavelengths, demonstrates great potential when combined with a newly designed Si-based CMOS circuit containing only blue and red colour filters. To demonstrate the effectiveness of this state-of-the-art hybrid colour image sensor, we acquired a real full-colour image using a camera that contained the organic-on-Si hybrid CMOS colour image sensor.

A Micromachined Monolithic Inkjet Print Head with Dome Shape Chamber

We describe a thermally driven monolithic inkjet print head, DomeJet, that consists of vertical refill channel and dome-shaped ink chambers. The vertical channel can be fabricated by anisotropic etching without photographic process and it has the same diameter with nozzle. Omega or ring type polysilicon heaters are integrated on top of each chamber. We study the performance of nozzles that are differently designed with respect to heater position and width. A 20 µm nozzle with “C type” heater shows stable ejection performance up to 20 kHz with droplet volume of 3.2 pl. Fifty-six nozzles are embedded at two columns on each chip and the pitch of nozzle is 1/150 inch. A printed image is successfully obtained using the fabricated head installed to a Samsung inkjet printer.

Microfluxgate sensor with amorphous cobalt (Co–Nb–Zr) soft magnetic core for electronic compass

A silicon based microfluxgate sensor with a cobalt based amorphous soft magnetic core for electronic compass is presented in this paper. A sputtered Co85Nb12Zr3 magnetic core having a rectangular ring shape is combined with microcopper solenoid coils for excitation and pickup, which were wound alternately around the core to increase the number of coil turns. The Co85Nb12Zr3 as a core material is adopted for improving properties of the magnetic core and easy integration with micromachining processes to achieve a small size of the sensor. The sputtered Co85Nb12Zr3 showed dc effective permeability of ∼10000 and an extremely low coercivity of ∼0.03Oe with the thickness of 1μm. The Co85Nb12Zr3 as a thin film core with high permeability and low coercivity was easily saturated by a low excitation magnetic field, enhancing the sensitivity and linearity of the microfluxgate sensor. Finally, the sensor showed excellent linearity response over the range of −300 to 300μT with sensitivity of 60V∕T at the excitation co...

Si-based optical I/O for optical memory interface

Optical interconnects may provide solutions to the capacity-bandwidth trade-off of recent memory interface systems. For cost-effective optical memory interfaces, Samsung Electronics has been developing silicon photonics platforms on memory-compatible bulk-Si 300-mm wafers. The waveguide of 0.6 dB/mm propagation loss, vertical grating coupler of 2.7 dB coupling loss, modulator of 10 Gbps speed, and Ge/Si photodiode of 12.5 Gbps bandwidth have been achieved on the bulk-Si platform. 2x6.4 Gbps electrical driver circuits have been also fabricated using a CMOS process.

Micro fluxgate sensor using solenoid driving and sensing coils

This paper describes a MEMS-based micro-fluxgate magnetic sensor composed of solenoid driving coil, sensing coil and rectangular-ring shaped magnetic core. Solenoid coils and magnetic core were separated by benzocyclobutene (BCB) having high resistivity and good planarization characteristics. To take advantage of low cost, small size and low power consumption, MEMS technology was used to fabricate micro fluxgate sensor. Copper coil with 20 /spl mu/m width and 3.5/spl mu/m thickness was electroplated on Cr (300/spl Aring/)/Au (1500/spl Aring/) films for driving and sensing coils. We designed the magnetic core into a rectangular-ring shape to reduce the magnetic flux leakage. Permalloy (NiO/sub 0.8/Fe/sub 0.2/) film with the thickness of 2 /spl mu/m was electroplated under 2000 gauss to induce magnetic anisotropy. The magnetic core had the high DC effective permeability of /spl sim/1,100 and coercivity of /spl sim/0.1 Oe. The fabricated fluxgate sensor had the sensitivity of /spl sim/650 V/T and power consumption of 40 mW at the driving frequency of 2 MHz and the driving voltage of 5 Vp-p.

A Micro-Fluxgate Magnetic Sensor Using Closely Coupled Excitation and Pick-Up Coils

This paper presents a micro-fluxgate magnetic sensor composed of a rectangular-ring shaped magnetic core and solenoid excitation and pick-up coils. In order to improve the sensitivity of sensing element, the excitation and pick-up Cu coils are formed as a closely coupled structure. This unique coil structure allows to excite the magnetic core in an optimal condition with reduced excitation current. The 11 μm thick excitation and pick-up Cu coils were electroplated using Cr (300 A) / Au (1500 A) seed layer. The 2.9 μm thick Ni 0.8 Fe 0.2 (permalloy) magnetic core layer was also electroplated with photoresist frame using sputtered Ni 0.8 Fe 0.2 seed layer. The rectangular-ring shaped core was covered by photoresist and wet etching using dilute sulfuric acid. The magnetic core has a DC permeability of ∼1100 and coercive field of 0.1 Oe. The magnetic core is easily saturated due to the low coercive field and closed magnetic path for the excitation field. The chip size of the fabricated sensing element is 1.3 × 1.0 mm 2 . Excellent linear response over the range of –100 μT to +100 μT is obtained with 14 V/T sensitivity at excitation sine wave of 3 V P-P and 150 kHz. This low magnetic field sensing element is very useful for various applications such as: portable navigation systems including north-up and map data scrolling, military research, medical research, and space research.

Performance Improvement in Dome Jet Inkjet Print Head by Measuring Temperature of Heater

This work has been done in an effort to enhance the performance and reliability of DomeJet print head. Dome Jet is a thermally driven monolithic inkjet print head that consists of dome-shaped ink chambers, thin film nozzle guides and polysilicon heaters of a omega shape integrated on the top surface of each chamber.