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유도결합 플라즈마 스퍼터링 장치에서 MgO의 반응성 증착 시 공정 진단
주정훈(Junghoon Joo) 한국표면공학회 2012 한국표면공학회지 Vol.45 No.5
Process analysis was carried out during deposition of MgO by inductively coupled plasma assisted reactive magnetron sputtering in Ar and O₂ ambient. At the initiation of Mg sputtering with bipolar pulsed dc power in Ar ambient, total pressure showed sharp increase and then slow fall. To analyse partial pressure change, QMS was used in downstream region, where the total pressure was maintained as low as 10<SUP>?5</SUP> Torr during plasma processing, good for ion source and quadrupole operation. At base pressure, the major impurity was H₂O and the second major impurity was CO/N₂ about 10%. During sputtering of Mg in Ar, H₂ soared up to 10.7% of Ar and remained as the major impurity during all the later process time. When O₂ was mixed with Ar, the partial pressure of Ar decreased in proportion to O₂ flow rate and that of H₂ dropped down to 2%. It was understood as Mg target surface was oxidized to stop H2 emission by Ar ion sputtering. With ICP turned on, the major impurity H2 was converted into H₂O consuming O₂and C was also oxidized to evolve CO and CO₂.
유도결합 플라즈마 시스템의 수치 모델링에서 가스 분배 특성 해석
주정훈(Junghoon Joo) 한국표면공학회 2013 한국표면공학회지 Vol.46 No.3
We have developed a 2D axi-symmetric numerical model for an inductively coupled plasma system in order to analyze gas mixing effect through a narrow gap shower head. For frictional flow, holes of 0.5 mm diameter and 2 mm length are approximately modeled in 2D. Gas velocity distribution 10 mm below the shower head showed 2 times difference between the center and the edge at 10 mTorr. At 10 mm above the wafer, it was increased to 6 times difference due to the pumping duct effect. The model with a 5 mm height buffer region of a shower head showed reasonable behavior of Ar discharge. The density of Ar metastable showed additional peak inside the buffer region around the edge holes.
[표면 기술의 응용] 사각형 유도 결합 플라즈마 시스템의 수치 모델링
주정훈(Junghoon Joo) 한국표면공학회 2012 한국표면공학회지 Vol.45 No.4
Low pressure inductively coupled plasma characteristics of argon and oxygen are numerically simulated for a 400 mm rectangular type system with a plasma fluid model. The results showed lower power absorption profile at the corner than a circular one in a 13.56 MHz driven 1.5 turn antenna system with a drift-diffusion and quasi-neutrality assumption. Ions controlled by electric field are more non-uniform than metastables and the power absorption profile of oxygen plasma is affected by horizontal gas flow pattern to show 25% lower power absorption at the pumping flange side. Oxygen negative ions which are generated in electron collisional dissociation of oxygen molecules was calculated as 0.1% of oxygen atoms with similar spatial profile.
MgO 증착을 위한 유도결합 플라즈마 마그네트론 스퍼터링에서 실시간 공정 진단
주정훈(Junghoon Joo) 한국표면공학회 2005 한국표면공학회지 Vol.38 No.2
A real-time monitoring of ICP(inductively coupled plasma) assisted magnetron sputtering of MgO was carried out using a QMS(quadrupole mass spectrometer), an OES(optical emission spectrometer), and a digital oscilloscope with a high voltage probe and a current monitor. At the time of ICP ignition, the most distinct impurity was OH emission (308.9 nm) which was dissociated from water molecules. For reactive deposition, oxygen was added to Ar and the OH emission intensity was reduced abruptly. When the discharge voltage was regulated by a PID controller from 240V(metallic mode) to 120V(oxide mode), the emission intensity from Mg (285.2 ㎚) changed proportionally to the discharge voltage, but the intensity of Ar 1(811.6 ㎚) was constant. At 100V of discharge voltage, Mg sputtering was almost stopped. Emissions from Ar 1(420.1 ㎚) and Mg I were dropped down to 1/10, but Ar 1(811.6 ㎚) didn't change. And the emission from atomic oxygen (O I, 777.3 ㎚) was increased to 10 times. These results are compatible with those from QMS study.
[표면 기술의 응용] 반응성 증착용 펄스 플라즈마 공정의 진단
주정훈(Junghoon Joo) 한국표면공학회 2012 한국표면공학회지 Vol.45 No.4
A real-time monitoring of an immersed antenna type inductively coupled plasma (ICP) was done with optical emission spectroscopy (OES) to check the reports that sputtered atom density is decreasing as the ICP power is increased1,2). At 10 mTorr pressure of Ar, Mg was sputtered by a bipolar pulsed power supply into 2 MHz ICP which has an insulator covered 2.5 turn antenna. Emitted light was collected in two different positions: above the target and inside the ICP region. With 100 W of Mg sputtering power, the intensities of Mg I (285.06 nm), Mg II (279.48 nm), Ar I (420.1 nm) were increased constantly with ICP power from 100 W to 600 W. At 500 W, the intensity of Mg+ exceeded that of Mg under PID controlled discharge voltage of 180 V. The ratio of Mg II/Mg I was increased from 0.45 to 2.71 approximately 6 times.
2D-ICP(inductively coupled plasma)에서 정전 탐침 삽입 시의 플라즈마 수치 계산
주정훈(Junghoon Joo) 한국표면공학회 2011 한국표면공학회지 Vol.44 No.1
Numerical modeling is used to investigate the perturbation of a single Langmuir probe (0.2 ㎜ diameter shielded with 6 ㎜ insulator) inserted along the center axis of a cylindrical inductively coupled plasma chamber filled with Ar at 10 mTorr and driven by 13 ㎒. The probe was driven by a sine wave. When the probe tip is close to a substrate by 24.5 ㎜, the probe characteristics was unperturbed. At 10 ㎜ above the substrate, the time averaged electric potential distribution around the tip was severly distorted making a normal probe analysis impossible.
수치모델을 이용한 pulsed dc bias ICP장치의 플라즈마 특성 해석
주정훈(Junghoon Joo) 한국표면공학회 2010 한국표면공학회지 Vol.43 No.3
Numerical analysis is done to investigate the effects of pulse bias on the plasma processing characteristics like ion doping and ion nitriding by using fluid dynamic code with a 2D axi-symmetric model. For 10 mTorr of Ar plasma, -1 ㎸ of pulse bias was simulated. Maximum sheath thickness was around 20 ㎜ based on the electric potential profile. The peak electron temperature was about 20 eV, but did not affect the averaged plasma characteristics of the whole chamber. Maximum ion current density incident on the substrate was 200 A/㎡ at the center, but was decreased down to 1/10th at radius 100 ㎜, giving poor radial uniformity.
주정훈(Junghoon Joo) 한국표면공학회 2019 한국표면공학회지 Vol.52 No.3
We have developed a numerical model to analyze flow dynamics and heat transfer characteristics of the cooling water in a circular rotating magnetron cathode by a moving boundary grid method realized in a commercial multiphysics package, CFD-ACE+. The numerical model is composed of a target, dual mass rotating cathode and cooling water connections. When the inlet and outlet of the cooling water are offset by the same distance from the rotation axis, the temperature at the center is higher by 50oC at maximum. At 5 mm away from the target surface, the temperature profile showed typical center high characteristic. At heat input of 30 kW, the maximum temperature change of the cooling water hits 6oC within 0.5 sec under 60 rpm. With a cooling water configuration of center in/edge out, the temperature of the center region of the target gets lowered. Within 100 seconds of plasma operation time, the cooling water temperature keeps getting higher.