• Macromolecular Research
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• 제12권6호
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• pp.608-614
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• 2004

Isotactic polypropylene (PP) surfaces were modified with argon and oxygen plasmas using a radio­frequency (RF) glow discharge at 240 mTorr and 40 W. The changes in topography and surface structure were investigated by atomic force microscopy (AFM) in conjunction with specular reflectance of infrared (IR) microspectroscopy. Under our operating conditions, the AFM image analysis revealed that longer plasma treatment resulted in significant ablation on the PP surface, regardless of the kind of plasma employed, but the topography was dependent on the nature of the gases. Specular reflectance IR spectroscopic analysis indicated that the constant removal of surface material was an important ablative aspect when using either plasma, but the nature of the ablative behavior and the resultant aging effects were clearly dependent on the choice of plasma. The use of argon plasma resulted in a negligible aging effect; in contrast, the use of oxygen plasma caused a noticeable aging effect, which was due to reactions of trapped or isolated radicals with oxygen in air, and was partly responsible for the increased surface area caused by ablation. The use of oxygen plasma is believed to be an advantageous approach to modifying polymeric materials with functionalized surfaces, e.g., for surface grafting of unsaturated monomers and incorporating oxygen-containing groups onto PP.

• Macromolecular Research
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• 제12권1호
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• pp.134-140
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• 2004

Semi-crystalline poly(ethylene terephthalate) (PET) film surfaces were modified with argon and oxygen plasmas by radio-frequency (RF) glow discharge at 240 mTorr/40 W; the changes in topography and surface structure were investigated by atomic force microscopy (AFM) in conjunction with specular reflectance of infrared microspectroscopy (IMS). Under our operating conditions, analysis of the AFM images revealed that longer plasma treatment results in significant ablation on the film surface with increasing roughness, regardless of the kind of plasma used. The basic topographies, however, were different depending upon the kind of gas used. The specular reflectance analysis showed that the ablative mechanisms of the argon and oxygen plasma treatments are entirely different with one another. For the Ar-plasma-treated PET surface, no observable difference in the chemical structure was observed before and after plasma treatment. On the other hand, the oxygen-plasma-treated PET surface displays a significant decrease in the number of aliphatic C-H groups. We conclude that a constant removal of material from the PET surface occurs when using the Ar-plasma, whereas preferential etching of aliphatic C-H groups, with respect to, e.g. , carbonyl and ether groups, occurs upon oxygen plasma.

• 반도체디스플레이기술학회지
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• 제8권3호
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• pp.31-37
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• 2009

This paper presents one and two dimensional simulation results with discontinuous features (shocks) of capacitively coupled rf plasmas. The model consists of the first two and three moments of the Boltzmann equation for the ion and electron fluids respectively, coupled to Poisson's equation for the self-consistent electric field. The local field and drift-diffusion approximations are not employed, and as a result the charged species conservation equations are hyperbolic in nature. Hyperbolic equations may develop discontinuous solutions even if their initial conditions are smooth. Indeed, in this work, secondary electron emission is shown to produce transient electron shock waves. These shocks form at the boundary between the cathodic sheath (CS) and the quasi-neutral (QN) bulk region. In the CS, the electrons emitted from the electrode are accelerated to supersonic velocities due to the large electric field. On the other hand, in the QN the electric field is not significant and electrons have small directed velocities. Therefore, at the transition between these regions, the electron fluid decelerates from a supersonic to a subsonic velocity in the direction of flow and a jump in the electron velocity develops. The presented numerical results are consistent with both experimental observations and kinetic simulations.

• 한국진공학회지
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• 제10권1호
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• pp.112-118
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• 2001

본 논문에서는 축 방향으로 자화된 용량결합형 13.65 MHz/40 KHz RF 방전에서 Langmuir Probe, Emissive Probe를 통해 이온 전류 밀도, 전자 온도, 플라즈마 전위의 자장 의존성 및 자기 바이어스 전위를 조사하였다. 자장을 인가함으로서 실험변수 범위 내에서 최대 3배의 이온 전류밀도증가를 얻었고 점화가능한 기체 압력의 최저값을 줄일 수 있었다. 플라즈마가 자화된 경우 공간 전위는 평균적으로 감소하였고 RF 전압의 한주기 동안 시 변동폭이 크게 증가하였다. 플라즈마 전위의 자장 의존성은 Particle-in-Cell Simulation을 수행하여 실험 결과와 비교하였다. 대표적 실험 조건에서 전자 온도는 자장에 따라 약 4 eV에서 5 eV로 약간 증가하는 경향을 보였으나 방전 주파수를 40 KHz로 줄인 경우 1.8 eV에서 0.8 eV로 감소하였다. 실험 장치의 응용 예로서 플루오로 카본 가스에 의한 식각실험이 수행되었다. 자화 플라즈마의 산화막 식각속도 증가를 확인함으로서 축방향 자장이 실제 공정에 긍정정인 영향을 미침을 확인 할 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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• pp.1066-1068
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• 1999

Magnetic field is commonly used in low temperature processing plasmas in order to obtain high density. E $\times$ B magnetron or surface multipole configuration were most popular. However, the properties of capacitively coupled rf plasma confined by axially applied static magnetic fields have rarely been studied. In this paper, the effects of magnetic field on the characteristics of 13.56MHz/40KHz argon plasma will be reported. Ion saturation current, electron temperature and plasma potential were measured by Langmuir probe and omissive probe. At low pressure region ($\sim$10mTorr), ion current was increased by a factor of 3 - 4 due to reduction of diffusion loss of charged particles to the wall. It was observed that magnetic field induces large time variation of the plasma potential. The experimental result was compared with particle-in-cell simulation. It was also observed that electron temperature tend to decrease with increasing magnetic induction level for 40KHz discharge.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.214-215
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• 2007

Etch rates and surface chemistry of phenol formaldehyde-based photoresist after short time $O_2\;and\;N_2O$ radio frequency (RF) plasma treatment depending on exposure time were investigated. It was found that the etch rate of photoresist sharply increased after discharge turn on and reached a limit with increase in plasma exposure time in both gases. X-ray photoelectron spectroscopy (XPS) analysis showed that the surface chemical structure become nearly constant after the treatment of 15 sec. Concentration of surface oxygen-containing groups after processing both in oxygen and in $N_2O$ plasmas is similar.

• 한국염색가공학회지
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• 제16권5호
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• pp.28-34
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• 2004

The polarizing film application exploits the unique physicochemical properties between PVA(Poly vinyl alcohol) film and CTA(Cellulose triacetate) film. However, hardly any research was aimed at improving the adhesion characteristics of the CTA film by radio frequency(RF) plasma treatment at argon(Ar) gaseous state. In this report, we deal with surface treatment technology for protective CTA film developed specifically for high adhesion applications. After Ar plasma, surface of the films is analyzed by atomic force microscopy(AFM), roughness parameter and peel strength. Furthermore, the wetting properties of the CTA film were studied by contact angle analysis. Results obtained for CTA films treated with a glow discharge showed that this technique is sensitive to newly created physical functions. The roughness and peel strength value increased with an increase in treatment time for initial treatment, but showed decreasing trend for continuous treatment time. The result of contact angle measurement refer that the hydrophilicity of surface was increased. AFM studies indicated that no considerable change of surface morphology occurred up to 3 minutes of treatment time, but a considerable uneven of surface structure resulted from treating time after 5 minutes.