• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.25-28
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• 2000

In this study, $Y_2$O$_3$ thin films were etched with inductively coupled plasma (ICP). The etch rate of $Y_2$O$_3$, and the selectivity of $Y_2$O$_3$ to YMnO$_3$ were investigated by varying Cl$_2$/(Cl$_2$+Ar) gas mixing ratio. The maximum etch rate of $Y_2$O$_3$, and the selectivity Of $Y_2$O$_3$ to YMnO$_3$ were 302/min, and 2.4 at Cl$_2$/(Cl$_2$+Ar) gas mixing ratio of 0.2 repectively. In x-ray photoelectron spectroscopy (XPS) analysis, $Y_2$O$_3$ thin film was dominantly etched by Ar ion bombardment, and was assisted by chemical reaction of Cl radical. These results were confirmed by secondary ion mass spectroscopy(SIMS) analysis. YCI, and YCl$_3$ existed at 126.03 a.m.u, and 192.3 a.m.u, respectively

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.21-24
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• 2000

Ferroelectric YMnO$_3$ thin films are excellent dielectric materials for high integrated ferroelectric random access memory (FRAM) with metal-ferroelectric-silicon field effect transistor (MFSFET) structure. In this study, YMnO$_3$ thin films were etched with C1$_2$/Ar gas chemistries in inductively coupled plasma (ICP). The maximum etch rate of YMnO$_3$ thin films is 285 $\AA$/min under C1$_2$/Ar of 10/0, 600 W/-200 V and 15 mTorr. The selectivities of YMnO$_3$ over CeO$_2$ and $Y_2$O$_3$ are 2.85, 1.72, respectively. The results of x-ray photoelectron spectroscopy (XPS) reflect that Y is removed dominantly by chemical reaction between Y and Cl, while Mn is removed more effective by Ar ion bombardment than chemical reaction. The results of secondary ion mass spectrometer (SIMS) were equal to these of XPS. The etch profile of the etched YMnO$_3$ film is approximately 65$^{\circ}$and free of residues at the sidewall.

• 대한전자공학회논문지SD
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• 제38권9호
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• pp.611-615
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• 2001

Y₂O₃ 박막은 MFISFET형 FRAM의 절연층으로써 응용이 기대되고 있다. 본 논문에서는 ICP에서 Cl₂/Ar 플라즈마를 이용하여 Y₂O₃ 박막을 식각하였다. Y₂O₃박막의 식각율과 YMnO₃ 에 대한 Y₂O₃ 박막의 선택비를 Cl₂/(Cl₂＋Ar) 가스혼합비에 따라 조사하였다. Cl₂/(Cl₂＋Ar) 가스 혼합비가 0.2일 때 Y₂O₃ 박막의 식각 속도는 302Å/min 으로 최대였으며, 그때 YMnO₃ 에 대한 Y₂O₃ 박막의 선택비는 2.4 이었다. Cl₂가스의 첨가량에 따라 Y₂O₃박막의 식각 속도에 어떠한 영향이 있는지 조사하기 위해 OES를 이용하였고, 식각 후 표면 반응을 알아보기 위하여 XPS 분석을 수행하였다. XPS 분석 결과 Y과 Cl과의 화학 반응이 있음을 확인하였고 그러한 분석결과는 SIMS 분석으로 확인되었다.

• 한국전기전자재료학회논문지
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• 제15권4호
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• pp.314-318
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• 2002

The etching behaviors of the ferroelectric $YMnO_3$ thin films were studied by an inductively coupled plasma (ICP). The maximum etch rate of $YMnO_3$ thin film is 300 ${\AA}/min$ at Ar/$Cl_2$of 2/8, RF power of 800W, dc bias voltage of 200V, chamber pressure of 15mTorr and substrate temperature of $30^{\circ}C$. Addition of $CF_4$ gas decrease the etch rate of $YMnO_3$ thin film. From the results of XPS analysis, nonvolatile $YF_x$ compounds were found on the surface of $YMnO_3$ thin film which is etched in Ar/$Cl_2$/CF$_4$plasma. The etch profile of YMnO$_3$film is improved by addition of $CF_4$ gas into the Ar/$Cl_2$ plasma. These results suggest that YF$_{x}$ compound acts as a sidewall passivants which reduce the sticking coefficient of chlorine on $YMnO_3$.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2004년도 제27회 학술발표회 초록집
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• pp.226-226
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• 2004

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.145-145
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• 2008

High-k materials have been paid much more attention for their characteristics with high permittivity to reduce the leakage current through the scaled gate oxide. Among the high-k materials, $ZrO_2$ is one of the most attractive ones combing such favorable properties as a high dielectric constant (k= 20 ~ 25), wide band gap (5 ~ 7 eV) as well as a close thermal expansion coefficient with Si that results in good thermal stability of the $ZrO_2$/Si structure. During the etching process, plasma etching has been widely used to define fine-line patterns, selectively remove materials over topography, planarize surfaces, and trip photoresist. About the high-k materials etching, the relation between the etch characteristics of high-k dielectric materials and plasma properties is required to be studied more to match standard processing procedure with low damaged removal process. Among several etching techniques, we chose the inductively coupled plasma (ICP) for high-density plasma, easy control of ion energy and flux, low ownership and simple structure. And the $BCl_3$ was included in the gas due to the effective extraction of oxygen in the form of $BCl_xO_y$ compounds. During the etching process, the wafer surface temperature is an important parameter, until now, there is less study on temperature parameter. In this study, the etch mechanism of $ZrO_2$ thin film was investigated in function of $Cl_2$ addition to $BCl_3$/Ar gas mixture ratio, RF power and DC-bias power based on substrate temperature increased from $10^{\circ}C$ to $80^{\circ}C$. The variations of relative volume densities for the particles were measured with optical emission spectroscopy (OES). The surface imagination was measured by scanning emission spectroscope (SEM). The chemical state of film was investigated using energy dispersive X-ray (EDX).

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.213-216
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• 2001

Etching behaviors of ferroelectric $YMnO_3$ thin films were studied by an inductively coupled plasma (ICP). Etch characteristic on ferroelectric $YMnO_3$ thin film have been investigated in terms of etch rate, selectivity and etch profile. The maximum etch rate of $YMnO_3$ thin film is $300{\AA}/min$ at $Ar/Cl_2$ of 2/8, RF power of 800W, dc bias voltage of 200V, chamber pressure of 15mTorr and substrate temperature of $30^{\circ}C$. Addition of $CF_4$ gas decrease the etch rate of $YMnO_3$ thin film. From the results of XPS analysis, YFx compounds were found on the surface of $YMnO_3$ thin film which is etched in $Ar/Cl/CF_{4}$ plasma. The etch profile of $YMnO_3$ film is improved by addition of $CF_4$ gas into the $Ar/Cl_2$ plasma. These results suggest that fluoride yttrium acts as a sidewall passivants which reduce the sticking coefficient of chlorine on $YMnO_3$.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.233-233
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• 2010

Magnetic random access memory (MRAM), based on magnetic tunnel junction (MTJ) and CMOS, is a prominent candidate among prospective semiconductor memories because it can provide nonvolatility, fast access time, unlimited read/write endurance, low operating voltage and high storage density. The etching of MTJ stack with good properties is one of a key process for the realization of high density MRAM. In order to achieve high quality MTJ stack, the use of CoFeB and IrMn magnetic films as free layers was proposed. In this study, inductively coupled plasma reactive ion etching of CoFeB and IrMn thin films masked with Ti hard mask was investigated in a $Cl_2$/Ar gas mix. The etch rate of CoFeB and IrMn films were examined on varying $Cl_2$ gas concentration. As the $Cl_2$ gas increased, the etch rate monotonously decreased. The effective of etch parameters including coil rf power, dc-bais voltage, and gas pressure on the etch profile of CoFeB and IrMn thin film was explored, At high coil rf power, high dc-bais voltage, low gas pressure, the etching of CoFeB and IrMn displayed better etch profiles. Finally, the clean and vertical etch sidewall of CoFeB and IrMn free layers can be achieved by means of thin Ti hard mask in a $Cl_2$/Ar plasma at the optimized condition.

• 한국전기전자재료학회논문지
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• 제15권4호
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• pp.319-324
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• 2002

In this study, the reduce of plasma etching damage in PZT thin film with addictive gas and re-annealing after etching have been investigated. The PZT thin films were etched as a function of $Cl_2/CF_4$ with addition of Ar and $O_2$ with inductively coupled plasma. The etch rates of PZT thin films were 1450 ${\AA}/min$ at 30% additive Ar and 1100 ${\AA}/min$ at 10% auditive $O_2$ into $Cl_2/CF_4$ gas mixing ratio of 8/2. In order to reduce plasma damage of PZT thin films after etching, the etched PZT thin films were re-annealed at various temperatures at $O_2$ atmosphere. From the hysteresis curries, the ferroelectric properties are improved by $O_2$ re-annealing process. The improvement of ferroelectric behavior at annealed PZT films is consistent wish the increase of the (100) and (200) PZT peaks revealed by x-ray diffraction (XRD). From x ray photoelectron spectroscopy (XPS) analysis, the intensity of Pb-O, Zr-O and Ti-O peak are increased and the chemical residue peak is reduced by $O_2$ re-annealing. The ferroelectric behavior consistent with the dielectric nature of $Ti_xO_y$ is recovered by $O_2$ recombination during rapid thermal annealing process.

• 한국전기전자재료학회논문지
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• 제14권7호
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• pp.551-556
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• 2001

In this work, the recovery of etching damage in the etched PZT thin film with $O_2$ annealing has been studied. The PZT thin films were etched as a function of Cl$_2$/Ar and additive CF$_4$ into Cl$_2$(80%) /Ar(20%). the etch rates of PZT thin films were 1600$\AA$/min at Cl$_2$(80%)/Ar(20%) and 1970 $\AA$/min at 30% additive Cf$_4$ into Cl$_2$(80%)/Ar(20%). In order to recover the characteristics of etched PZT thin films, the etched PZT thin films were annealed in $O_2$ atmosphere at various temperatures. From the hysteresis curves, ferroelectrical properties are improved by $O_2$ annealing process. The improvement of ferroelectric behavior is consistent with the increase of the (100) and (200) PZT phase revealed by x-ray diffraction (XRD). From x-ray photoelectron spectroscopy (XPS) analysis, intensities of Pb-O, Zr-O and Ti-O peak increase and the chemical residue peak is reduced by $O_2$ annealing. From the atomic force microscopy (AFM) images. it shows that the surface morphology of re-annealed PZT thin films after etching is improved.