• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.307-307
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• 2013

초고집적 회로에 적용되는 반도체 소자의critical dimension (CD)이 수 nano 사이즈로 줄어들고 있기 때문에, 다양한 물질의 식각을 할 때, 건식식각의 중요성이 더 강조되고 있다. 특히 $SiO_2$와 같은 유전체 물질을 식각할 때, plasma process induced damages (P2IDs)가 관찰되어 왔고, 이러한 P2IDs를 줄이기 위해, pulsed-time modulation plasma가 광범위하게 연구되어 왔다. Pulsed plasma는 정기적으로 radio frequency (RF) power on과 off를 반복하여 rf power가 off된 동안, 평균전자 온도를 낮춤으로써, 웨이퍼로 입사되는 전하 축적을 효과적으로 줄일 수 있다. 또한 fluorocarbon plasmas를 사용하여 $SiO_2$를 식각하기 위해 Dual-Frequency Capacitive coupled plasma (DF-CCP)도 널리 연구되어 왔는데, 이것은 기존의 방법과는 다르게 plasma 밀도와 ion bombardment energy를 독립적으로 조절 가능하다는 장점이 있어서 미세 패턴을 식각할 때 효과적이다. 본 연구에서는 Source power에는 60 MHz pulsed radio frequency (RF)를, bias power에는 2 MHz continuous wave (CW) rf power가 사용된 system에서 Ar/$C_4$ F8/$O_2$ 가스 조합으로, amorphous carbon layer (ACL)가 hard mask로 사용된 $SiO_2$를 식각했다. 그리고 source pulse의 duty ratio와 pulse frequency의 효과에 따른 $SiO_2$의 식각특성을 연구하였다. 그 결과, duty ratio의 감소에 따라 $SiO_2$, ACL의 etch rate이 감소했지만, $SiO_2$/ACL의 etch selectivity는 증가하였다. 반면에 pulse frequency의 변화에 따른 두 물질의 etch selectivity는 크게 변화가 없었다. 그 이유는 pulse 조건인 duty ratio의 감소가 전자 온도 및 전자 에너지를 낮춰 $C_2F8$가스의 분해를 감소시켰으며, 이로 인해 식각된 $SiO_2$의 surface와 sidewall에 fluorocarbon polymer의 형성이 증가하였기 때문이다. 또한 duty ratio의 감소에 따라 etch selectivity뿐만 아니라 etch profile까지 향상되는 것을 확인할 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.51-51
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• 2008

Carbon nanotubes (CNTs) have long been reported as an ideal material due to their excellent electrical conductivity and chemical and mechanical stability as well as their high aspect ratios for field emission devices. CNT emitters made by screen printing the organic binder-based CNT paste may act as a source to release gases inside a vacuum panel. These residual gases may cause a catastrophic damage by electrical arcing or ion bombardment to the vacuum microelectronic devices and may change their physical or electrical properties by adsorbing on the CNT emitter surface. In this study, we analyzed the composition of residual gases inside the vacuum-sealed panel by residual gas analyzer (RGA), investigating the effects of individual gases of different kinds at several pressures on the field emission characteristics of CNT emitters. The residual gases included $H_2$, CO, $CO_2$, $N_2$, $CH_4$, $H_2O$, $C_2H_6$, and Ar. Effect of residual gases on the field emission was studied by observing the variation of the pulse voltages with the duty ratio of3.3% to keep the constant emission current of $28{\mu}A$. Each gas species was introduced to a vacuum chamber up to three different pressures ($5\times10^{-7}$, $5\times10^{-6}$, and $5\times10^{-5}$ torr) each for 1 h while electron emission was continued. The three different pressure regions were separated by keeping a high vacuum of $\sim10^{-8}$ torr for a 1 h. The emission was terminated 6 h after the third gas exposure was completed. Field emission characteristics under residual gases will be discussed in terms of their adsorption and desorption on the surface of CNTs and the resultant change of work function.

• 한국안전학회지
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• 제33권1호
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• pp.41-46
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• 2018

Experiments were carried out the phenomenal observation on effect of corona treated hotmelt laminating film in process of manufacture by 2 kinds of rolling speed and electric power variatons. Surface treatment by corona which is exposure of film surface to electron of ion bombardment, rather than mere exposure to active species, like atomic oxygen or ozone, can enhance adhesion by removing contaminant, electret, roughening surface, and introducing reactive chemical group. Reactive neutrals, ions, electron and photons generated during the corona treatment interact simultaneously with polymers to alter surface chemical composition, wettability, and thus film adhesion. However, it is highly recommended that extensive chains scission is avoided because it can lead to side-effect by forming sticky matter, resulting in dropouts. This paper reviews principles of surface preparation of polypropylene substrate by corona discharging. In addition, the experimental section provides a description of parameter optimization on corona discharging treatment and its side-effect. Experimental results are discussed in terms of surface wetting as determined by contact angle and SEM measurements. When the rolling speed of the film decreased from 1.666 [m / sec] to 0.083 [m / sec], contact angle decreased from $80[^{\circ}]$ to $64[^{\circ}]$, and the wettability was greatly improved. As the supply power increased from 0.4 [kVA] to 2 [kVA] at the corona discharge surface treatment, the contact angle decreased from $77[^{\circ}]$ to $65[^{\circ}]$, and the wettability was greatly improved.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.190-194
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• 2002

In this study, the etching of Au thin films have been performed in an inductively coupled CF4/Cl2/Ar plasma. The etch properties were measured as the CF4 adds from 0 % to 30 % to the Cl2/(Cl2 + Ar) gas mixing ratio of 0.2. Other parameters were fixed at a rf power of 700 W, a dc bias voltage of 150 V, a chamber pressure of 15 mTorr, and a substrate temperature of $30^{\circ}C$. The highest etch rate of the Au thin film was 370 nm/min at a 10 % additive CF4 into Cl2/(Cl2 + Ar) gas mixing ratio of 0.2. The surface reaction of the etched Au thin films was investigated using x-ray photoelectron spectroscopy (XPS) analysis. From x-ray photoelectron spectroscopy (XPS) analysis, the intensities of Au peaks are changed. There is a chemical reaction between Cl and Au. Au-Cl is hard to remove on the surface because of its high melting point and the etching products can be sputtered by Ar ion bombardment. We obtained the cleaned and steep profile.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.472-472
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• 2011

The capacitive coupled plasma (CCP) has been extensively used in the semiconductor industry because it has not only good uniformity, but also low electron temperature. But CCP source has some problems, such as difficulty in varying the ion bombardment energy separately, low plasma density, and high processing pressure, etc. In this reason, dual frequency CCP has been investigated with a separate substrate biasing to control the plasma parameters and to obtain high etch rate with high etch selectivity. Especially, in this study, we studied on the etching of $SiO_2$ by using the pulse-time modulation in the dual-frequency CCP source composed of 60 MHz/ 2 MHz rf power. By using the combination of high /low rf powers, the differences in the gas dissociation, plasma density, and etch characteristics were investigated. Also, as the size of the semiconductor device is decreased to nano-scale, the etching of contact hole which has nano-scale higher aspect ratio is required. For the nano-scale contact hole etching by using continuous plasma, several etch problems such as bowing, sidewall taper, twist, mask faceting, erosion, distortions etc. occurs. To resolve these problems, etching in low process pressure, more sidewall passivation by using fluorocarbon-based plasma with high carbon ratio, low temperature processing, charge effect breaking, power modulation are needed. Therefore, in this study, to resolve these problems, we used the pulse-time modulated dual-frequency CCP system. Pulse plasma is generated by periodical turning the RF power On and Off state. We measured the etch rate, etch selectivity and etch profile by using a step profilometer and SEM. Also the X-ray photoelectron spectroscopic analysis on the surfaces etched by different duty ratio conditions correlate with the results above.

• 한국재료학회지
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• 제11권9호
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• pp.769-775
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• 2001

High quality PZT piezoelectric thin films were sputter- deposited on$ RuO_2$/$SiO_2$/Si substrates by using 2-step deposition method. As the first step, PZT seed layers were fabricated at a low temperature($475^{\circ}C$ ) to form a pure perovskite phase by reducing the volatility of Pb oxide. and then, as the second step, the PZT films were deposited at high temperatures ($530^{\circ}C$~$570^{\circ}C$) to reduce the defect density in the films. By this method, the pure perovskite phase was obtained at high deposition temperature range ($530^{\circ}C$~$570^{\circ}C$) and the superior electrical properties of PZT films were obtained on $RuO_2$substrate : 2Pr : 60$\mu$C/$\textrm{cm}^2$, $E_c: 60kV/cm, \;J_t: 10^{-6}A/cm^2\; at\; 250kV/cm$. The residual stress of PZT films fabricated by the 2-step deposition method was tensile and below 150MPa. It was attempted to control the residual stress in the PZT films by applying a negative bias to the substrate. As the amplitude of the substrate bias was increased, the residual tensile stress was slightly decreased, however, the ferroelectric properties of PZT films were degraded by ion bombardment.

• 한국전기전자재료학회논문지
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• 제16권4호
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• pp.298-303
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• 2003

Bi$_4$-$_{x}$EU$_{x}$Ti$_3$O$_{12}$ (BET) thin films were etched by inductively coupled CF$_4$/Ar plasma. We obtained the maximum etch rate of 78 nm/min at the gas mixing ratio of CF$_4$(10%)/Ar(90%). The variation of volume density for F and Ar atoms are measured by the optical emission spectroscopy. As CF$_4$increased in CF$_4$/Ar plasma, the emission intensities of F increase, but Ar atoms decrease, which confirms our suggestion that emission intensity is proportional to the volume density of atoms. From X-ray photoelectron spectroscopy, the intensities of the Bi-O, the Eu-O and the Ti-O peaks are changed. By pure Ar plasma, intensity peak of the oxygen-metal (O-M : TiO$_2$, Bi$_2$O$_3$, Eu$_2$O$_3$) bond was seemed to disappear while the intensity of pure oxygen peak showed an opposite tendency. After the BET thin films was etched by CF$_4$/Ar plasma, the peak intensity of O-M bond increase slowly, but more quickly than that of peak belonged to pure oxygen atoms due to the decrease of Ar ion bombardment. Scanning electron microscopy was used to investigate etching Profile. The Profile of etched BET thin film was over 85$^{\circ}$./TEX>.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기물성,응용부문
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• pp.202-203
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• 2006

In the AC PDP, the MgO film is used as electrode protective film. This film must provide excellent ion bombardment protection, high secondary electron emission, and should be high transparent to visible radiation. In this study, we investigated the relations between the crystal orientation and e-beam evaporation process parameters. The crystal orientation of the MgO layer depends on the conditions of deposition. The parameters are the thickness of the MgO film $1000{\AA}-6500{\AA}$, the deposition rate $200{\AA}/min{\sim}440{\AA}/min$, the temperature $150^{\circ}C{\sim}250^{\circ}C$, and the distance between crucible and substrate 11cm ${\sim}$ 14cm. The temperature of substrate and evaporation rate of source material, or deposition rate of the film, are definitely related to the crystal orientation of the MgO thin film. The crystal orientation can be changed by the distance between the target(MgO tablet) and the substrate. However, the crystal orientation is not much affected by the thickness of MgO thin film.

• 한국진공학회지
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• 제7권4호
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• pp.390-396
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• 1998

헬리콘(Helicon) 플라즈마로부터 중성입자 흐름을 생성하여 높은 에너지의 이온에 의한 기판의 물리적, 전기적 손상을 방지할 수 있는 실리콘 식각공정이 연구되었다. 기판의 하부에 영구자석을 설치하여 cusp모양의 자계를 형성하므로써 이온 및 전자를 기판으로부 터 제거되도록 하였고 이러한 방법으로 완전히 제거되지 않는 이온의 제거를 위해서 기판 하부에 양의 전압을 가하여 자계나 전계에 영향을 받지 않는 중성입자 흐름을 얻을 수 있도 록 하였다. 발생시킨 자계 및 전계의 의해 기판 상부에서의 전자밀도는 자계나 전계가 가해 지지 않은 경우에 비해 약1/1,000정도로 낮아졌으며, 이온밀도 또한 약1/10정도로 감소하였 다. 이러한 공정을 통해 얻어진 실리콘의 식각속도는 $Cl_2$와 10%의 SF6를 혼합하여 사용할 때 $8.5{\times}10^{-4}$Torr의 압력에서 약100$\AA$/min이하로 매우 낮았으며 실리콘의 식각이 비등방성 을 가지며 진행될 수 있음이 보여졌다.

• 한국전기전자재료학회논문지
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• 제16권5호
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• pp.378-384
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• 2003

Etching species in CF$_4$/Ar plasma and the behavior of etching rate of Bi$_4$-$_{x}$L$_{x}$rTi$_3$O$_2$ (BLT) films were investigated in inductively coupled plasma (ICP) reactor in terms of etch parameters. The etching rate as functions of CF$_4$ contents showed the maximum 803 $\AA$/min at 20% CF$_4$ addition in CF$_4$/Ar plasma. The increase of RF power and DC bias voltage caused to an increase of etch rate. The variation of relative volume densities for F and he atoms were measured with the optical emission spectroscopy (OES). The chemical states of BLT were investigated with using X-ray photoelectron spectroscopy (XPS). XPS narrow scan analysis shows that La-fluorides remained on the etched surface. The presence of maximum etch rate at CF$_4$(20%)/Ar(80%) may be explained by the concurrence of two etching mechanisms such as physical sputtering and chemical reaction. The roles of he ion bombardment include destruction of metal (Bi, La, Ti)-O bonds as well as assistant for chemical reaction of metals with fluorine atoms.oms.