Boong-Joo Lee

Carbon Nanotube Interconnection and Its Electrical Properties for Semiconductor Applications

In this work, the integration and its electrical properties of a carbon nanotube (CNT) interconnect for semiconductor applications are presented. A series array of 1000 vias made of vertically grown CNTs was achieved with uniform electrical resistance within the wafer. The integration of CNT interconnection was implemented with conventional semiconductor processes by following sequential steps: bottom electrode and via hole patterning, CNT growth and planarization, and top electrode patterning on the wafer. Multi walled CNTs (MWCNTs) as the interconnection, titanium nitride as the bottom electrode, and aluminum with a titanium contact layer as the top electrode were used. We demonstrated well-defined CNT via interconnect with 700 nm via holes on a full-sized wafer. A via resistance of 350 kΩ and a CNT density of 2.7×1010/cm2 were achieved with a small resistance variation within the wafer, which also corresponded to 51.3 kΩ per MWCNT 10 nm in diameter. Possible approaches to further decrease of electrical resistance are suggested.

Fabrication and Characterization of Ni-Cr Alloy Thin Films for Application to Precision Thin Film Resistors

Ni(75 wt.%)-Cr(20 wt.%)-Al(3 wt.%)-Mn(4 wt.%)-Si(1 wt.%) alloy thin films were prepared using the DC magnetron sputtering process by varying the sputtering conditions such as power, pressure, substrate temperature, and post-deposition annealing temperature in order to fabricate a precision thin film resistor. For all the thin film resistors, sheet resistance, temperature coefficient of resistance (TCR), and crystallinity were analyzed and the effects of sputtering conditions on their properties were also investigated. The oxygen content and TCR of Ni-Cr-Al-Mn-Si resistors were decreased by increasing the sputtering pressure. Their sheet resistance, TCR, and crystallinity were enhanced by elevating the substrate temperature. In addition, the annealing of the resistor thin films in air at a temperature higher than 300℃ lead to a remarkable rise in their sheet resistance and TCR. This may be attributed to the improved formation of NiO layer on the surface of the resistor thin film at an elevated temperature.

Floating-gate type organic memory device with organic insulator film of plasma polymerized styrene

Plasma polymerized styrene (ppS) thin films were prepared and used as gate insulator and tunneling layer in a floating-gate type organic memory device. To investigate feasibility of the ppS thin film for application in non-volatile organic memory, an organic thin film transistor (OTFT) and a floating-gate type organic memory device were fabricated. Current–voltage (I–V) characteristics of the OTFT and floating-gate type organic memory device were comparatively investigated, and hysteresis in the I–V characteristics of both devices was studied. A pseudo-charge-storage phenomenon was found for the ppS insulator thin film in the OTFT and floating-gate type organic memory device. The floating-gate type organic memory device revealed a reasonable hysteresis voltage of 27 V. It was confirmed that the ppS could be applied to fabricate an alternative floating-gate type organic memory device with promising memory function.

Process Condition Considered Preparation and Characterization of Plasma Polymerized Methyl Methacrylate Thin Films for Organic Thin Film Transistor Application

Plasma polymerized methyl methaclylate (ppMMA) thin films were prepared with various process conditions such as inductively coupled plasma (ICP) power, substrate bias power, working pressure, substrate heating temperature, substrate position, and monomer flow rate. Thickness, surface morphology, dielectric constant, and leakage current of the ppMMA thin films were investigated for application to organic thin film transistor as gate dielectric. Deposition rate of over 8.6 nm/min, dielectric constant of 3.4, and leakage current density of 8.9 ×10-9 A/cm-2 at electric field of 1 MV/cm were achieved for the ppMMA thin film prepared at the optimized process condition: plasma power of RF 100 W; Ar flow rate of 20 sccm; working pressure of 5 mTorr; substrate temperature of 100 °C; substrate position of 100 mm. The ppMMA thin film was then applied to pentacene based organic thin film transistor (OTFT) device fabrication. The OTFT device with 80 nm thick pentacene semiconductor layer showed field effect mobility of 0.144 cm2 V-1 s-1 and threshold voltage of -1.72 V.

Floating-Gate Type Organic Memory with Organic Insulator Thin Film of Plasma Polymerized Methyl Methacrylate

To fabricate organic memory device by entirely dry process, plasma polymerized methyl methacrylate (ppMMA) thin films were prepared and they were used as both tunneling layer and gate insulator layer in a floating-gate type organic memory device. The ppMMA thin films were prepared with inductively coupled plasma (ICP) source combined with stabilized monomer vapor control. The ppMMA gate insulator thin film revealed dielectric constant of 3.75 and low leakage current of smaller than 10-9 A/cm. The floating-gate type organic memory device showed promising memory characteristics such as memory window value of 12 V and retention time of over 2 h, where 60 V of writing voltage and -30 V of erasing voltage were applied, respectively.

Polymer thin film organic transistor characteristics with plasma treatment of interlayers

In this paper, we fabricated insulator thin films by plasma polymerization method for organic thin film transistors insulator layer. For improving the electrical characteristics of organic transistor, we treated the semiconductor thin film with plasma. As results, the surface energy of organic transistor was increased from to and the mobility of organic transistor was increased , that is increased 29% average ratio. Therefore, we have known that oragnic transistors mobility can improve with plasma treatment of semiconductor thin films surface.

Organic Transistor Characteristics with Electrode Structures

In this paper, We have fabricated PMMA thin films by plasma polymerization method for organic thin film transistors insulator layer. For improving the characteristics of organic transistor, we tested transistors mobility and output values with organic transistors electrode structures. As a results, the mobility of top contact was 8×10 -3 (cm

Operating characteristics of Floating Gate Organic Memory

Abstract Organic memory devices were made using the plasma polymerization method. The memory device consistedof ppMMA(plasma polymerization MMA) thin films as the tunneling and insulating layer, and a Au thin film as the memory layer, which was deposited by thermal evaporation. The organic memory operation theory was developed according to the charging and discharging characteristics of floating gate type memory, which would be measuredby the hysteresis voltage and memory voltage with the gate voltage values. The I-V characteristics of the fabricatedmemory device showed a hysteresis voltage of 26 [V] at 60 ∼ -60 [V] double sweep measuring conditions. The programming voltage was applied to the gate electrode in accordance with the result of this theory. A programmingvoltage of 60[V] equated to a memory voltage of 13[V], and 80[V] equated to a memory voltage of 18[V]. The memory voltage of approximately 40 [%]increased with increasing programming voltage. The charge memory layer charging or discharging according to the theory of the memory was verified experimentally.

The Long Last Sustain Method for Improving High-Temperature Misdischarge in an AC-PDP

This paper proposes a long last sustain waveform to improve the high-temperature misdischarge in an AC-PDP. We have confirmed that, when applying the interval time during which the X electrode and the Y electrode are grounded before the reset period in the next subfield after the sustain period at high temperature, the VA minimum voltage is reduced. The interval time reduces the probability of exoelectron emission at high temperatures. Therefore, the interval time can improve the high-temperature misdischarge. However, due to the nature of the ADS driving method, there are limitations when increasing the driving time. Thus, we proposed the long last sustain waveform, in which either the X electrode or the Y electrode is applied to VS voltage, instead of the interval time. The VA minimum voltage is significantly decreased, when the long last sustain waveform was applied within the same interval time, rather than grounding the X and Y electrodes. In particular, the effect of the X long last sustain waveform showed the best results. We also proposed the ascending X long last sustain waveform to optimize the length of the long last sustain waveform according to each subfield. The ascending X long last sustain waveform further reduced the VA minimum voltage. In this paper, the VA minimum voltage can be decreased to approximately 12 V, by applying the proposed ascending X long last sustain waveform, in comparison with the existing drive method, at higher temperatures.

XPS Investigation and Field Emission Property of the Ar Plasma Processed Carbon Nanotube Films

Carbon nanotube films were fabricated by the catalytic CVD method. Plasma processed time effects on the field emission property were studied. The atomic structure was observed by using X-ray photoelectron spectroscopy (XPS). The surface composition changes were observed on the plasma processed CNT films. The O1s/C1s signal ratio and the Fls/Cls signal ratio changed from 1.1 % to 24.65 % and from 0 % to 3.1 % with plasma process time, respectively. We could guess it from these results that the Ar plasma process could change the surface composition effectively. In the case of the original-CNT film, no carbon shift was observed. In the case of the Ar plasma processed CNT films, however the oxygen related carbon shifts were observed. This oxygen related carbon shift at higher binding energy implies the increment of amount of the oxygen. It`s possible that the increment of these bonds between carbon and oxygen results in the improvement of field emission performance.