Se-Jin Kyung

Low angle forward reflected neutral beam source and its applications

As one of the many nano-device fabrication techniques employed in the semiconductor industry, neutral beams are being examined using various methods to solve possible charge-related problems that occur during device processing. This review introduces a neutral beam generated by surface neutralization of an ion beam using a low angle forward reflection technique and explains its application to various areas such as surface treatments and etching. The neutralization efficiency of an ion beam using a low angle forward reflection technique was approximately 99.7%. When a metal-oxide-semiconductor device was etched using a reactive neutral beam, it was confirmed that charge-related problems such as aspect-ratio-dependent etching and gate oxide charging could be removed using reactive neutral beam etching instead of conventional reactive ion etching. Neutral beams can be beneficial to other devices such as the III-V device and field emission device.

Characteristics of SiO2-Like Thin Film Deposited by Atmospheric-Pressure PECVD Using HMDS ∕ O2 ∕ Ar

SiO 2 -like thin films were deposited at low temperatures ( 95% could be obtained with a deposition rate of approximately 21 nm/min.

Improvement of field emission from screen-printed carbon nanotubes by He∕(N2,Ar) atmospheric pressure plasma treatment

A screen-printed carbon nanotube (CNT) paste for applications to field emission emitters was treated with He, He∕Ar, and He∕N2 atmospheric pressure plasmas. The effect of the different plasma treatments on the field emission characteristics of the screen-printed CNTs was investigated. The atmospheric pressure plasma applied to the screen-printed CNT paste for 10s resulted in a reduction in the turn-on electric field. In particular, the application of a He∕N2 plasma treatment decreased the turn-on electric field from 3.13to1.29V∕μm and increased the field enhancement factor from 737 to 2775 after the treatment. These results suggest that an adequate atmospheric pressure plasma treatment of screen-printed CNTs can be effective in enhancing the field emission properties.

The Effect of N2 Flow Rate in He/O2/N2 on the Characteristics of Large Area Pin-to-Plate Dielectric Barrier Discharge

In this study, the effects of N2 flow rate in the He/O2/N2 gas mixture on the characteristics of a pin-to-plate dielectric barrier discharge (DBD) having the size of 100 mm ×1000 mm have been investigated for the application to flat panel display processing such as photoresist ashing. The pin-to-plate DBD showed about 70–120% higher photoresist ashing rate at the same applied voltage compared to the conventional DBD. The addition of 3 slm of N2 to He(10 slm)/O2(3 slm) showed the highest photoresist ashing rate of about 580 nm/min for the pin-to-plate DBD at 12 kV of AC voltage. The increase of N2 flow rate in He/O2 gas mixture up to 3 slm appeared to increase the density of N2+ ions and N2 metastables while the oxygen atomic density appeared to decrease continuously. The increase of photoresist ashing rate with the increase of N2 flow rate up to 3 slm was related to the increase of the substrate surface temperature by the increased collision of N2+ ions and N2 metastables with the substrate.

Characteristics of SiO x Thin Film Deposited by Atmospheric Pressure Plasma-Enhanced Chemical Vapor Deposition Using PDMS ∕ O2 ∕ He

Silicon oxide thin films were deposited using a modified, pin-to-plate, dielectric barrier discharge system with polydimethylsiloxane (PDMS), bubbled by He/O 2 gas mixtures at atmospheric pressure and a temperature of less than 50°C. Increasing PDMS flow rate in the gas mixture increased the deposition rate, but also increased the surface roughness due to the formation of particles in the gas phase as a result of increased PDMS and silanol groups, leading to incomplete decomposition or oxidation of PDMS. The increase in the ratio of oxygen flow rate to PDMS flow rate decreased the surface roughness with increasing deposition rate due to the efficient oxidation of PDMS. However, when the oxygen flow rate was raised above 1 slm, due to the increased oxidation of PDMS in the gas phase and the decreased PDMS dissociation by the decreased plasma density, the surface roughness was again increased with decreasing deposition rate. At the gas mixture of 9 slm PDMS/He and 1 slm oxygen, a smooth, SiO 2 -like thin film was obtained at a deposition rate of 12 nm/min.

Atmospheric Pressure Remote Plasma Ashing of Photoresist Using Pin-To-Plate Dielectric Barrier Discharge

Plasma ashing of photoresist (PR) was investigated with N2/O2/SF6 gas mixtures using remote-type atmospheric pressure plasma generated by a pin-to-plate type dielectric barrier discharge. When a certain amount of O2 and SF6 were added together to N2, higher PR ashing achieved at N2 (70 slm)/O2 (200 sccm)/SF6 (3 slm).

Study of selective amorphous silicon etching to silicon nitride using a pin-to-plate dielectric barrier discharge in atmospheric pressure

Remote-type atmospheric pressure plasmas were generated using a modified dielectric barrier discharge with the powered electrode consisting of multipins instead of a conventional blank planar plate. For the N2∕NF3 gas mixture, a high etch rate of a:Si close to 115nm∕s was obtained by adding 300SCCM (SCCM denotes cubic centimeter per minute at STP) of NF3 to N2 [50SLM (standard liters per minute)] at an ac rms voltage of 8.5kV (2.5kW, 30kHz). However, the selectivity of a:Si to Si3N4 was as low as 1.3. A selectivity of a:Si∕Si3N4>5.0 could be obtained while maintaining an etch rate of a:Si at 110nm∕s by adding 250SCCM CF4 to the N2 (50SLM)∕NF3 (300SCCM) mixture through the formation of a C–F polymer layer preferentially on the Si3N4 surface.

A Study of Electrical Damage to a-Si:H Thin Film Transistor during Plasma Ashing by a Pin-to-Plate Type Atmospheric Pressure Plasma

In this study, the effect of the plasma ashing of the photoresist on a-Si:H thin film transistor (TFT) devices carried out using an atmospheric pressure plasma on the electrical damage to the TFT devices was investigated. By exposing the TFT devices to the plasma with a photoresist ashing rate of about 860 nm/min for up to 120 s, their electrical characteristics were significantly degraded, possibly due to charge trapping in the SiNx of the passivation layer and gate insulator and to bond breaking in a-Si:H. The degradation of the field effect mobility, Ioff, and Ion/Ioff ratio of the devices is believed to be mostly related to the bond breaking in the a-Si:H and charge trapping caused by the UV radiation, while the change in the threshold voltage appears to be mostly related to the surface charging caused by the charged species in the plasma. The damaged TFT devices, however, could be fully repaired by conventional annealing in a furnace at 290°C in N2 for 60 min.