• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.2
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• pp.128-131
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• 2004

In this study Bosch etching process repeating etch and deposition by STS-ICP ASEHR was evaluated. Fundamentally etch depth changes were affected by thickness of deposited PR, $SiO_2$ and depth, and pattern size on the substrate. However etch rates were observed to be changed by variable parameters such as platen power, coil power, and process pressure. Etch rate showed $1.2\mu{m}/min$ and sidewall profile showed $90\pm0.2^\circ$ with platen power 12W, coil power 500W, and etch/passivation cycle 6/7sec. It was confirmed that this result was very typical to Bosch process utilizing ICP.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.213-213
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• 2010

Magnetic random access memory (MRAM), based on magnetic tunnel junction (MTJ) and CMOS, is one of the best semiconductor memories because it can provide nonvolatility, fast access time, unlimited read/write endurance, low operating voltage and high storage density. For the realization of high density MRAM, the etching of MTJ stack with good properties is one of a key process. Recently, there has been great interest in the MTJ stack using MgO as barrier layer for its huge room temperature MR ratio. The use of MgO barrier layer will undoubtedly accelerate the development of MTJ stack for MRAM. In this study, high-density plasma reactive ion etching of MgO films was investigated in an inductively coupled plasma of $Cl_2$/Ar gas mixes. The etch rate, etch selectivity and etch profile of this magnetic film were examined on vary gas concentration. As the $Cl_2$ gas concentration increased, the etch rate of MgO monotonously decreased and etch slop was slanted. The effective of etch parameters including coil rf power, dc-bais voltage, and gas pressure on the etch profile of MgO thin film was explored, At high coil rf power, high dc-bais voltage, low gas pressure, the etching of MgO displayed better etch profiles. Finally, the clean and vertical etch sidewall of MgO films was achieved using $Cl_2$/Ar plasma at the optimized etch conditions.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.8 s.185
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• pp.47-53
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• 2006

The purpose of this study was to investigate the significant characteristics in spray of industrial etch-nozzle for the design of process. The experiment was carried out with different spray pressure and industrial nozzle in wet etch. The characteristics of liquid spray, such as axial velocity and sauter mean diameter measurements were obtained by PDA. And impact force was calculated from spray characteristics. It was found that the fluid with higher spray pressure resulted in the smaller SMD and the higher droplet velocity and impact force. The depth of etch was increased in case of high spray pressure. In the case of injection angle oscillated between $20^{\circ}$, the result indicated constant effect of etch. The correlation between the spray characteristics and etch ones were analyzed. The depth of etch had good positive correlation with axial velocity and impact force. The result clearly shows that the characteristics in wet etch are strongly related to the spray characteristics with process.

• Korean Journal of Materials Research
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• v.31 no.3
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• pp.162-171
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• 2021

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.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1305-1308
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• 2003

A new technique is presented to construct a predictive model of plasma etch process. This was accomplished by combining a backpropagation neural network (BPNN) and a genetic algorithm (GA). The predictive model constructed in this way is referred to as a GA-BPNN. The GA played a role of controlling training factors simultaneously. The training factors to be optimized are the hidden neuron, training tolerance, initial weight magnitude, and two gradients of bipolar sigmoid and linear functions. Each etch response was optimized separately. The proposed scheme was evaluated with a set of experimental plasma etch data. The etch process was characterized by a $2^3$ full factorial experiment. The etch responses modeled are aluminum (A1) etch rate, silica profile angle, A1 selectivity, and dc bias. Additional test data were prepared to evaluate model appropriateness. The GA-BPNN was compared to a conventional BPNN. Compared to the BPNN, the GA-BPNN demonstrated an improvement of more than 20% for all etch responses. The improvement was significant in the case of A1 etch rate.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.309-311
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• 2003

The effects of etch parameters on dry etching of BLT thin films were investigated with ICP etch system in $Cl_2$/Ar and $BCl_2/Cl_2$/Ar gas. The etch rate and etch selectivity of BLT films were examined as a function of gas concentration, ICP power, bias power, and pressure. The maximum etch rates of 191.1 nm/min was obtained at the mixed etch condition of $BCl_3(20%)/Cl_2$/Ar, 700 W ICP RF power, 12 mTorr pressure and 400 W substrate RF power. As ICP power and rf power increased, the etch rate of BLT increased. As pressure increased, the etch rate of BLT decreased. The changes of radicals in both $Cl_2$/Ar and $BCl_3/Cl_2$/Ar plasma were measured with using optical emission spectroscopy (OES).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.1
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• pp.1-6
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• 2004

Dry etch characteristics of polysilicon with HBr/O$_2$ inductively coupled plasma (ICP) have been investigated. We determined etch late, uniformity, etch profiles, and selectivity with analyzing the cross-sectional scanning electron microscopy images obtained from top, center, bottom, right, and left positions. The etch rate of polysilicon was about 2500 $\AA$/min, which meets with the mass production for devices. The wafer level etch uniformity was within $\pm$5 ％. Etch profile showed 90$^{\circ}$ slopes without notches. The selectivity over photoresist was between 2:1∼4.5:1, depending on $O_2$ flow rate. The HBr-ICP etching showed higher PR selectivity, and sharper profile than the conventional Cl$_2$-RIE.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.4
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• pp.315-319
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• 2007

A technique to model plasma processes was presented. This was accomplished by combining the backpropagation neural network (BPNN) and genetic algorithm (GA). Particularly, the GA was used to optimize five training factor effects by balancing the training and test errors. The technique was evaluated with the plasma etch data, characterized by a face-centered Box Wilson experiment. The etch outputs modeled include Al etch rate, AI selectivity, DC bias, and silica profile angle. Scanning electron microscope was used to quantify the etch outputs. For comparison, the etch outputs were modeled in a conventional fashion. GABPNN models demonstrated a considerable improvement of more than 25% for all etch outputs only but he DC bias. About 40% improvements were even achieved for the profile angle and AI etch rate. The improvements demonstrate that the presented technique is effective to improving BPNN prediction performance.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.6
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• pp.373-377
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• 2000

For 6H-SiC single crystals which was obtained by sublimation growth (modified Lely process), the relation between the defects and the etch pits to be formed at the site of dislocations were discussed. Typical hexagonal etch pits were formed on (0001) basal plane. The similar hexagonal etch pit shapes were formed on the site of micropipe defects and it was realized that internal planar defects was formed with the same matrix crystal structure as grown crystals, through the observation of the etching morphology at those internal defects.

• Journal of the Semiconductor & Display Technology
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• v.20 no.4
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• pp.146-150
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• 2021

Plasma information based virtual metrology (PI-VM) that predicts wafer-to-wafer etch rate variation after wet cleaning of plasma facing parts was developed. As input parameters, plasma information (PI) variables such as electron temperature, fluorine density and hydrogen density were extracted from optical emission spectroscopy (OES) data for etch plasma. The PI-VM model was trained by stepwise variable selection method and multi-linear regression method. The expected etch rate by PI-VM showed high correlation coefficient with measured etch rate from SEM image analysis. The PI-VM model revealed that the root cause of etch rate variation after the wet cleaning was desorption of hydrogen from the cleaned parts as hydrogen combined with fluorine and decreased etchant density and etch rate.