• Electrical & Electronic Materials
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• v.9 no.9
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• pp.918-924
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• 1996

A downstream oxygen plasma is generated by capacitively coupled RF power and applied to photoresist stripping. Stripping rate (ashing rate) is measured in terms of RF power, chamber pressure, oxygen flow rate and temperature. Ashing reaction is thermally activated and depends on oxygen radical density. The ashing process is optimized to have the high ashing rate, good uniformity and minimal plasma damage using a statistical method.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.464-464
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• 2012

본 연구에서는 DBD (Dielectric Barrier Discharge)방식을 통해 발생된 대기압 plasma를 이용한 Photoresist (PR) Ashing에 관한 연구를 하였다. 사용된 DBD 반응기는 기존의 blank planar plate 형태의 Power가 인가되는 anode 부분과 Dielectric Barrier 사이 공간을 액상의 도전체로 채워 넣은 형태의 전극이 사용 하였으며, 인가 Power는 40 kHz AC 최대 인가 전압 15 kV를 사용 하였고(본 연구에서 인가 power는 30 KHz,전압 14 KV를 고정시킴) 플라즈마를 발생시 라디칼의 활성화를 유지하기 위해 전극 온도가 $180^{\circ}C$ 정하였다. Feeding 가스는 N2, 반응가스로는 CDA(Clean Dry Air), SF6와 CF4가스를 사용 하였으며 모든 공정은 In-line type으로 시편을 처리 하였다. CDA ratio의 경우에 질소대비 0.2%때 이송속도 30 mm/sec 1회 처리 기존 PR ashing은 최대 $320{\AA}$의 ashing 두께를 얻을 수 있었다. SF6와 CDA가스를 같이 반응하는 경우 ratio는 CDA : SF6 = 0.6% : 0.6%에서 PR ashing rate이 $841{\AA}/pass$의 값을 얻을 수 있었고, CDA가스만 첨가하는 경우보다 약2.6배 증가함을 관찰할 수 있었다. CF4 가스를 사용하는 경우 ratio는 CDA : CF4 = 0.2% : 0.2%에서 PR ashing rate이 $687{\AA}/pass$의 값을 얻을 수 있으며 CDA가스만 첨가하는 경우보다 약 2.1배 증가함을 관찰할 수 있었다. 그리고 PR ashing rate가 가스첨가종류와 비율에 따라서 변화함을 관찰하였고 최적조건을 찾기 위해 연구를 진행하였다. 추후 PR ashing rate가 향상을 하기 위해 가스혼합비율 및 stage 온도등 조건을 조절하여 공정최적조건을 얻기 위해 연구를 진행하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1500-1503
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• 2009

In this paper, we studied about atmospheric pressure remote plasma ashing of photoresist(PR), by using a modified dielectric barrier discharge(DBD). The effect of various gas combinations such as $N_2/O_2$, $N_2/O_2+SF_6$ on the changes PR ashing rate was investigated as a function of power. The maximum PR ashing rate of 1850 nm/min was achieved at $N_2$ (70 slm)/ $O_2$ (200 sccm) + $SF_6$ (3 slm). We found that as the oxygen and fluorine radical peaks were increased, the ashing rate is increased, too.

• Journal of the Semiconductor & Display Technology
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• v.7 no.2
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• pp.35-38
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• 2008

This study shows the improvement of PR-Ashing rates in semi-conductor process using Atmospheric Plasma. Taguchi method is used to improve Ashing rates of photo-resist that is spread on the surface of a wafer. Improvement of Ashing rates is acquired through the decision of the effective factors and suitable combination of the factors. The results show the contribution rate of each factor and the effectiveness of Plasma for PR-Ashing process in this system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.152-155
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• 2003

Ashing of photoresist was investigated in dielectric barrier discharges in atmospheric pressure by changing applied voltage, frequency, flow rate. we analyzed the plasma by Optical Emission Spectroscopy(OES) to monitor the variation of active oxygen species. Another new peaks of oxygen radical is observed by addition of argon gas. This may explain the increase in ashing rate with argon addition. With the results of Optical Emission Spectroscopy(OES), we can find the optimized ashing conditions. MIS capacitor for monitoring charging damage by the plasma was also studied. The results suggest the dielectric barrier discharges(DBD) can be an efficient, alternative Plasma source for general surface processing.

• Transactions on Electrical and Electronic Materials
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• v.7 no.4
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• pp.204-209
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• 2006

Photo Resist (PR) ashing process was carried out with the atmospheric pressure- dielectric barrier discharge (ADBD) using $SF_6/N_2/O_2$. Ashing rate (AR) was sensitive to the mixing ratio of the oxygen and nitrogen of the blower type of ADBD asher. The maximum AR of 5000 A/min was achieved at 2% of oxygen in the $N_2$ plasma. With increasing the oxygen concentration to more than 2% in the $N_2$ plasma, the discharge becomes weak due to the high electron affinity of oxygen, resulting in the decrease of AR. When adding 0.5% of SF6 to $O_2/N_2$ mixed plasma, the PR AR increased drastically to 9000 A/min and the ashed surface of PR was smoother compared to the processed surface without $SF_6$. Carbon Fluorinated polymer may passivate the PR surface. It was also observed that the glass surface was not damaged by the fluorine.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.339-342
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• 1998

Plasma etching of photoresist needs high etch rate, good uniformity and rae, good uniformity and low damage in low cost. ICP asher is expected to satisfy these requriement for next eneration semiconductor devices. ICPsimulator has been used to design the ashing chamber to redcue the development time and cost, and its results have been verified by QMS, OES and langmuir probe measurments. Plasma characteristics are monitored in terms of RF power and chamber pressure.

• The Journal of the Korean dental association
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• v.12 no.7
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• pp.521-526
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• 1974

This observation was carried out to investigate the inorganic constituents of dental calculus of varying locations and different ages. Supragingival calculus was obtained from 540 patients with the periodontal disease. The results were as follows : 1. The weight loss rate in ashing by aging was the highest in the 2nd decade (63.7%) and followed in order by 3rd decade (60.8%), seventh decade 959.8%), fourth decade (55.9%), sixth decade (52.6%) and fifth decade (43.2%). 2. The weight loss rate by ashing was more prominent in the buccal surfaces of the upper posterior teeth (62.0%) than in the lingual surface of the lower anterior teeth (59.7%). 3. The difference in contents of the inorganic constituents by sex was not remarkable. (male, Ca:373.0 P:333.9, female, Ca: 380.2, P: 339.6 ㎍/mg dry weight) 4. In the dry calulus, contents of the inorganic constituents were as follows: Ca:325.8 P:269.10 Mg:1.21 Na:8.44 K:1.32, Zn:0.67 ㎍/mg. 5. The Ca/P ratio was the lowest in the upper anterior region (1.11) and the highest in the lower posterior region (1.29) and the average was 1.20.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.2
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• pp.95-100
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• 1998

A helical inductively coupled plasma asher, which produces low energy and high density plasma, has been built and investigated for photoresist stripping process. Oxygen ion density in the order of $10^{11}/cm^3$ is measured by Langmuir probe, and higher oxygen radical density is observed by Optical Emission Spectrometer. As RF source power is increased, the plasma density and thus photoresist stripping rate are increased. Independent RF bias power to the wafer stage provides a dc bias to the wafer and an ability to add the ion assisted reaction. At 1 KW of the source power, the coupling mechanism of the RF power to the plasma is changed from the inductive mode to the capacitive one at about 1 Torr. This change causes the plasma density and ashing rate decreases abruptly. The critical pressure of the mode change becomes larger with larger RF power.

• Analytical Science and Technology
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• v.33 no.4
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• pp.186-196
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• 2020

A simple and rapid preconcentration method of actinide from seawater using Actinide resin was developed and tested with the seawater spiked with a known U and Th. The developed method of Actinide resin based on column chromatography is less time-consuming and requires less labor compared with a typical co-precipitation technique for preconcentration of actinides. U and Th, which are relatively weak-bonded with Actinide resin among actinides, were used to determine the optimum flow rate of seawater sample and evaluate the capacity of Actinide resin to concentrate actinides from seawater. A flow rate of 50 mL min^-1 was available with Actinide resin 2 mL (BV, bed volume). When 5 or 10 L of seawater containing U were loaded on Actinide resin (2 mL, BV) at 50 mL min^-1, the recovery of U was 93 % and 86 %, respectively. For extraction of actinides bound with Actinide resin, we compared three methods: solvent extraction, ashing-acid digestion, and ashing-microwave digestion. Ashing-microwave digestion method shows the best performance of which is the recovery of 100 % for U and 81 % for Th. For the preconcentration of actinides in 200 L of seawater, a typical coprecipitation method requires 2-3 days, but the developed method in this study is achieved the high recovery of actinides within 12 h.