Dry etching of copper thin films is performed using high density plasma of ethylenediamine (EDA)/ hexafluoroisopropanol (HFIP)/Ar gas mixture. The etch rates, etch selectivities and etch profiles of the copper thin films are improved by adding HFIP to EDA/Ar gas. As the EDA/HFIP concentration in EDA/HFIP/Ar increases, the etch rate of copper thin films decreases, whereas the etch profile is improved. In the EDA/HFIP/Ar gas mixture, the optimal ratio of EDA to HFIP is investigated. In addition, the etch parameters including ICP source power, dc-bias voltage, process pressure are varied to examine the etch characteristics. Optical emission spectroscopy results show that among all species, [CH], [CN] and [H] are the main species in the EDA/HFIP/Ar plasma. The X-ray photoelectron spectroscopy results indicate the formation of CuCN compound and C-N-H-containing polymers during the etching process, leading to a good etch profile. Finally, anisotropic etch profiles of the copper thin films patterned with 150 nm scale are obtained in EDA/HFIP/Ar gas mixture.

Reactive Ion Etching (RIE) and wet etching are employed in existing texturing processes to fabricate solar cells. Laser etching is used for particular purposes such as selective etching for grooves. However, such processes require a higher level of cost and longer processing time and those factors affect the unit cost of each process of fabricating solar cells. As a way to reduce the unit cost of this process of making solar cells, an atmospheric plasma source will be employed in this study for the texturing of crystalline silicon wafers. In this study, we produced the atmospheric plasma source and examined its basic properties. Then, using the prepared atmospheric plasma source, we performed the texturing process of crystalline silicon wafers. The results obtained from texturing processes employing the atmospheric plasma source and employing RIE were examined and compared with each other. The average reflectance of the specimens obtained from the atmospheric plasma texturing process was 7.88 %, while that of specimens obtained from the texturing process employing RIE was 8.04 %. Surface morphologies of textured wafers were examined and measured through Scanning Electron Microscopy (SEM) and similar shapes of reactive ion etched wafers were found. The Power Conversion Efficiencies (PCE) of the solar cells manufactured through each process were 16.97 % (atmospheric plasma texturing) and 16.29% (RIE texturing).

Micro-electromechanical systems (MEMS) 구조물용 고 종횡비의 외팔보 제작을 목적으로 초임계 이산화탄 소를 사용한 건식 식각 실험을 진행하였다. 건식 식각 실험은 초임계 이산화탄소에 50% 불산 (HF) 원액과 공용매 (물, 메탄올, 에탄올, 이소프로필 알콜)를 사용하여 진행되었다. 희생 실리카 층을 식각하여 드러난 MEMS 외팔보 빔 은 주사전자현미경을 이용하여 관찰하였다. HF원액을 사용한 건식 식각 실험은 종횡비 1 : 150의 외팔보 빔까지 기 판과 접착없이 단독으로 서 있는 형태로 제작되었다. 공용매로 메탄올과 에탄올을 사용한 건식 식각의 결과에서는 종 횡비 1 : 75 까지 접착없이 제작할 수 있었고, 이소프로필 알콜을 공용매로 첨가한 실험 결과에서는 종횡비 1 : 37.5 까지 접착없이 제작할 수 있었다. 본 연구의 결과 건식 식각과정에서 알콜계 공용매의 첨가는 대체로 식각 성능을 저 하시킴을 알 수 있었다.

We report on the capacitively coupled O2 plasma etching of PMMA and polycarbonate (PC) with a diffusion pump. Plasma process variables were process pressure and CCP power at 5 sccm O2 gas flow rate. Characterization was done in order to analyze etch rate, etch selectivity, surface roughness, and morphology using stylus surface profilometry and scanning electron microscopy. Self bias decreased with increase of process pressure in the range of 25~180 mTorr. We found an important result for optimum pressure for the highest etch rate of PMMA and PC, which was 60 mTorr. PMMA and PC had etch rates of 0.46 and 0.28 μm/min under pressure conditions, respectively. More specifically, etch rates of the materials increased when the pressure changed from 25 mTorr to 60 mTorr. However, they reduced when the pressure increased further after 60 mTorr. RMS roughnesses of the etched surfaces were in the range of 2.2~2.9 nm. Etch selectivity of PMMA to a photoresist was ~1.5:1 and that of PC was ~0.9:1. Etch rate constant was about 0.04 μm/minW and 0.02 μm/minW for PMMA and PC, respectively, with the CCP power change at 5 sccm O2 and 40 mTorr process pressure. PC had more erosion on the etched sidewall than PMMA did. The OES data showed that the intensity of the oxygen atomic peak (777.196 nm) proportionally increased with the CCP power.

This study investigates GaAs dry etching in capacitively coupled BCl3/N2 plasma at a low vacuum pressure (>100 mTorr). The applied etch process parameters were a RIE chuck power ranging from 100~200W on the electrodes and a N2 composition ranging from 0~100% in BCl3/N2 plasma mixtures. After the etch process, the etch rates, RMS roughness and etch selectivity of the GaAs over a photoresist was investigated. Surface profilometry and field emission-scanning electron microscopy were used to analyze the etch characteristics of the GaAs substrate. It was found that the highest etch rate of GaAs was 0.4μm/min at a 20 % N2 composition in BCl3/N2 (i.e., 16 sccm BCl3/4 sccm N2). It was also noted that the etch rate of GaAs was 0.22μm/min at 20 sccm BCl3 (100 % BCl3). Therefore, there was a clear catalytic effect of N2 during the BCl3/N2 plasma etching process. The RMS roughness of GaAs after etching was very low (~3nm) when the percentage of N2 was 20 %. However, the surface roughness became rougher with higher percentages of N2.

O2plasma와 H(hfac)을 이용한 Cu 박막의 건식 식각을 조사하였다. 휘발성이 큰 Cu(hfac)2와 H2O를 탈착시키기 위하여 O2 Plasma를 이용한 Cu 박막의 산화와 생성된 Cu 산화막을 H(hfac)과의 반응으로 제거하는 공정으로 식각을 수행하였다. Cu 박막의 식각율은 50-700 /min의 범위를 보였으며, 기판온도, H(hfac)/O2 유량비, plasma power에 따라 변하였다. Cu 박막의 식각율은 기판온도 215˚C보다 높은 온도구간에서 RF power가 증가함에 따라 증가하였고, 산화 공정과 H (hfac)과의 반응이 균형을 이루는 최적의 H (hfac)/O2 유량비는 1:1임을 확인하였다. Ti mask를 사용한 Cu Patterning은 유량비 1 : 1, 기판온도 250˚C에서 실시하였고, 30˚외 taper slope를 갖는 등방성 etching profile을 얻을 수 있었다. Taper angle을 갖는 Cu 건식 patterning은 고해상도의 대면적 thin film transistor liquid-crystal(TFT-LCDs)를 위래 필요한 것으로써 기판온도, RF power, 유량비를 조절한 one-step 공정으로부터 성공적으로 얻을 수 있었다.

P-type의 단결정 실리콘 위에 1000a의 열산화막을 성장시킨후 5500a의 다결정 실리콘으로 증착된 시료를 가지고 HBr/Cl2/He-O2 혼합기체로 식각할 때 시료의 식각 특성에 관한 H2-O2 기체함량. RF 전력, 압력에 대한 영향을 XPS(X-ray photoelectron Spectroscopy)와 SEM(Scanning Electron Microscopy)으로 조사하였다. HBr/Cl2/He-O2 혼합기체로 식각되는 동안 형성된 다결정 실리콘 식각속도는 H2-O2 함량 증가에 따라 증가하였으며 식각잔유물은 RF 전력과 압력변화에 의해 영향은 받지 않는 것으로 나타났으며, 다결정 실리콘 측벽에서의 증착속도는 낮은 RF전력과 높은 압력에서 높게 나타났다. 다결정 실리콘 식각 잔유물의 결합에너지는 안정한 SiO2인 열산화막의 경우보다 높으므로 식각 잔유물은 SiOχ(χ>2)의 화합결합을 가지는 산화물과 같은 잔유물로 생각된다.