• 한국세라믹학회:학술대회논문집
• /
• 한국세라믹학회 2003년도 추계총회 및 연구발표회 초록집
• /
• pp.145.1-145
• /
• 2003

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
• /
• pp.408-408
• /
• 2012

It is well known that magnetic random access memory (MRAM) is nonvolatile memory devices using ferromagnetic materials. MRAM has the merits such as fast access time, unlimited read/write endurance and nonvolatility. Although DRAM has many advantages containing high storage density, fast access time and low power consumption, it becomes volatile when the power is turned off. Owing to the attractive advantages of MRAM, MRAM is being spotlighted as an alternative device in the future. MRAM consists of magnetic tunnel junction (MTJ) stack and complementary metal- oxide semiconductor (CMOS). MTJ stacks are composed of various magnetic materials. FePt thin films are used as a pinned layer of MTJ stack. Up to date, an inductively coupled plasma reactive ion etching (ICPRIE) method of MTJ stacks showed better results in terms of etch rate and etch profile than any other methods such as ion milling, chemical assisted ion etching (CAIE), reactive ion etching (RIE). In order to improve etch profiles without redepositon, a better etching process of MTJ stack needs to be developed by using different etch gases and etch parameters. In this research, influences of $O_2$ gas on the etching characteristics of FePt thin films were investigated. FePt thin films were etched using ICPRIE in $CH_4/O_2/Ar$ gas mix. The etch rate and the etch selectivity were investigated in various $O_2$ concentrations. The etch profiles were studied in varying etch parameters such as coil rf power, dc-bias voltage, and gas pressure. TiN was employed as a hard mask. For observation etch profiles, field emission scanning electron microscopy (FESEM) was used.

• 한국세라믹학회지
• /
• 제42권4호
• /
• pp.232-236
• /
• 2005

$LiNbO_{3}$ optical waveguide 구조를 neutral loop discharge plasma 방법으로 식각시 As과 $C\_{3}F_{8}$가 혼합된 가스 유량에 따른 식각속도와 표면조도 값의 특성을 관찰하였다. 식각 후 식각속도와 식각단면은 scanning electron microscopy로 비교 분석하였으며, 표면조도는 atomic force microscopy로 측정하였다. Ar과 $C_{3}F_{8}$가 혼합된 가스 유량비를 각각 0.1-0.5로 증가시킴에 따라 식각속도와 표면조도는 0.2에서 가장 높게 나타났으며, bias power를 증가함에 따라 300W에서 가장 우수한 식각속도와 가장 평탄한 표면 형상을 얻을 수 있었다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
• /
• pp.168-168
• /
• 2008

Dimension of a transistor has rapidly shrunk to increase the speed of device and to reduce the power consumption. However, it is accompanied with several problems like direct tunneling through the gate dioxide layer and low conductivity characteristic of poly-Si gate in nano-region. To cover these faults, study of new materials is urgently needed. Recently, high dielectric materials like $Al_2O_3$, $ZrO_2$, and $HfO_2$ are being studied for equivalent oxide thickness (EOT). However, poly-Si gate is not compatible with high-k materials for gate-insulator. Poly Si gate with high-k material has some problems such as gate depletion and dopant penetration problems. Therefore, new gate structure or materials that are compatible with high-k materials are also needed. TiN for metal/high-k gate stack is conductive enough to allow a good electrical connection and compatible with high-k materials. According to this trend, the study on dry etching of TiN for metal/high-k gate stack is needed. In this study, the investigations of the TiN etching characteristics were carried out using the inductively coupled $BCl_3$-based plasma system and adding $Cl_2$ gas. Dry etching of the TiN was studied by varying the etching parameters including $BCl_3$/Ar gas mixing ratio, RF power, DC-bias voltage to substrate, and $Cl_2$ gas addition. The plasmas were characterized by optical emission spectroscopy analysis. Scanning electron microscopy was used to investigate the etching profile.

• 대한기계학회논문집A
• /
• 제25권12호
• /
• pp.1911-1918
• /
• 2001

Recently the non-destructive test technique which uses the grain boundary etching characteristics owing to the variation of material structures has been proposed. However, during in-serviced GEM test there are a lot of variables such as the changes of temperature and concentration of etching solution, the roughness condition of surface polished etc.. The purpose of this paper is to investigate the influences of these test variables on GEM test results in order to establish a reliable and sensitive of GEM evaluation technique. The experiments are conducted in various solution temperatures, 10$\^{C}$, 15$\^{C}$, 20$\^{C}$, and 25$\^{C}$ and in 70% and 100% concentrations of that, and in various surface roughnesses polished by #800, #2000, and 0.3㎛ alumina powder. Through the test with variables, it is verified that the decrease of temperature and concentration of etching solution and the coarsened surface roughness by not using polishing cloth and powder induce some badly and/or greatly influences on GEM test results like grain boundary etching width(W$\_$GB) and intersecting point ratio(N$\_$i/N$\_$0/). Therefore, to get reliable and good GEM test results, it must be prepared the surface of specimen polished by polishing cloth and 0.3㎛ alumina powder and the saturated picric acid solution having 25$\^{C}$ and be maintained the constant temperature(25$\^{C}$) during GEM test.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2000년도 전력전자학술대회 논문집
• /
• pp.400-403
• /
• 2000

This paper deals with the active clamp ZVS flyback converter for semiconductor plasma etching system. The proposed converter has the characteristics of the good power facter low switching noise and efficiency improvement. The characteristics are verified through simulation results. Furthermore the ringing effect due to output capacitance of the main switch can be eliminated by use of active clamp circuit.

• E2M - 전기 전자와 첨단 소재
• /
• 제9권2호
• /
• pp.188-195
• /
• 1996

The AlSi etching process using the MERIE type reactor carried out with different process parameters such as C1$_{2}$ and N$_{2}$ gas flow rate, RF power and chamber pressure. The etching characteristics were evaluated in terms of etch rate, selectivity, uniformity and etched profile. As the N2 gas flow rate is increased, the AlSi etch rate is decreased and uniformity has remained constant within .+-.5%. The etch rate is increased and uniformity is decreased, according to increment of the C1$_{2}$ gas flow rate, RF power and chamber pressure. Selective etching of TEOS with respect to AlSi is decreased as the RF power is increased while it is increased by increment of the C1$_{2}$ gas flow rate and chamber pressure, on the other hand, selective etching of photoresist with respect to AlSi is increased by increment of the C1$_{2}$ gas flow rate and chamber pressure, it is decreased as the N$_{2}$ gas flow rate is increased.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 하계학술대회 논문집
• /
• pp.644-647
• /
• 2001

Amorphous As-Ge-Se-S thin films have been studied with the aim of identifying optimum etching condition which can be used to produce holographic grating structure for use as diffractive optical elements. In this study, holographic gratings have been formed using He-Ne laser(632.8nm), and fabricated by the method of wet etching using NaOH etchant with various concentration(0.26N, 0.33N, 0.40N). The diffraction efficiency was obtained by +1st order intensity of the diffracted beam. The formed grating profiles were observed by atomic force microscope and showed that the expected grating profile could be achieved by controlling the etching time. Over-etching resulted in under-cutting of the grating lines. The highest 1st order diffraction efficiency for these gratings was about 5.05%.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2010년도 하계학술대회 논문집
• /
• pp.339-339
• /
• 2010

Photo-assisted wet chemical etching of GaN thin film was studied using KOH based solutions. A $2{\mu}m-2{\mu}m$ titanium line-and-space pattern was used as a etching mask. It is found that the etching characteristics of the GaN thin film is strongly dependent on the pattern direction by unisotropic property of KOH based solution. When the pattern was aligned to the [$11\bar{2}0$] directions, ($10\bar{1}n$)-facet is revealed constructing V-shaped sidewalls.

• 제어로봇시스템학회논문지
• /
• 제4권4호
• /
• pp.506-516
• /
• 1998

In this paper, an algorithm is proposed to detect the malfunction of plasma-etching characteristics using EPD signal trajectories. EPD signal trajectories offer many information on plasma-etching process state, so they must be considered as the most important data sets to predict the wafer states in plasma-etching process. A recent work has shown that EPD signal trajectories were successfully incorporated into process modeling through critical parameter extraction, but this method consumes much effort and time. So Principal component analysis(PCA) can be applied. PCA is the linear transformation algorithm which converts correlated high-dimensional data sets to uncorrelated low-dimensional data sets. Based on this reason neural network model can improve its performance and convergence speed when it uses the features which are extracted from raw EPD signals by PCA. Wafer-state variables, Critical Dimension(CD) and uniformity can be estimated by simulation using neural network model into which EPD signals are incorporated. After CD and uniformity values are predicted, proposed algorithm determines whether malfunction values are produced or not. If malfunction values arise, the etching process is stopped immediately. As a result, through simulation, we can keep the abnormal state of etching process from propagating into the next run. All the procedures of this algorithm can be performed on-line, i.e. wafer to wafer.