• Journal of the Korean Ceramic Society
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• v.38 no.1
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• pp.74-83
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• 2001

FHD(Flame Hydrolysis Deposition) 공정은 광통신에서 사용되는 수동형 집적광학소자를 제작하는 공정으로서, SiCl$_4$를 형성하는 방법이다. 이 FHD 공정은 화염 형성에 관여하는 장비의 조건에 따른 매우 다양한 공정인자에 의하여 박막의 조성이 결정되므로, 박막의 조성을 예측하는 것이 용이하지 않았다. 본 연구에서는 FHD 공정에서 첨가가스의 유량을 제어하여 박막의 조성 및 광학적 특성을 예측할 수 있는 공정 분석의 기초자료를 제공하기 위하여 FTIR과 ICP-AES를 이용하여 실리카 soot의 조성분석에 대한 연구를 수행하였다. FTIR 흡수스펙트럼을 통해 실리카 soot에 존재하는 Si-O, B-O, OH($H_2O$) 농도의 변화를 관찰할 수 있었으며, ICP-AES를 통해 B-O의 흡수스펙트럼의 변화를 B의 농도와 정량적으로 연관지을 수 있었다.

• Journal of the Korean Ceramic Society
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• v.37 no.6
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• pp.524-529
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• 2000

Silica slab wavegudie was fabricated on Si substrates by FHD for planar optical passive devices. The slab waveguide consists of lower clad and core layers, where core layer index is controlled by GeO2 addition. Doping of GeO2 in silica is difficult because of the low deposition density due to nonspherical particle generation in FHD process. Silica core particles deposited at various conditions such as flame temperature and substrate scanning were analyzed by SEM and TEM. As the flame temperature increased, the surface roughness of the core layer was decreased up to 3.6 nm after consolidation. Index difference and thickness of core of slab waveguide were 0.3%, 8$\mu\textrm{m}$ respectively. Measured optical loss at TE mode was <0.04 dB/cm at 1.3$\mu\textrm{m}$ and <0.06 dB/cm at 1.55$\mu\textrm{m}$.

• Journal of the Korean Ceramic Society
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• v.35 no.4
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• pp.364-370
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• 1998

Boron-phoshor-silicate glass was fabricated on Si substrates by FHD(Flame Hydrolysis Deposition) The microstructrue of silica soot deposited at various conditon such as composition and substrate temperature was analysed by SEM. After consolidation the refractive index and composition of the silica layer were in-vestigated. For refractive index control B, P and Ge were used as additive elements while B and Ge oxides are easily mixed into $SiO_2$, P oxide($B_2O_3$) doping is difficult because of the volatile property due to low melt-ing point. Boron-phosphorous-silicate glass (BPSG) layer were fabricated using bertical torch and optimized flame temperature substrate temperature and distance of torch and substrate. P concentration of BPSG lay-er measured 3.3 Wt% and the consolidation temperature was lower than $1180^{\circ}C$. The measured refractive index of BPSG silica layer in $1.55\;\mu\textrm{m}$ wavelength was $1.4480{\pm}1{\times}10^{-1}$ and the thickness was $22{\pm}1\;\mu\textrm{m}$.

• Journal of the Korean Ceramic Society
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• v.39 no.3
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• pp.278-285
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• 2002

For planar optical devices, silica film deposited by FHD was fabricated at low temperature. To prepare silica film at low temperature, we have changed B, P amounts and investigated consolidation effect with varying consolidation temperature and atmosphere on microstructural change, and also observed optical property. The optimum consolidation temperature in He was lower than that of other atmosphere, its temperature could be lowered to 1050$^{\circ}C$. As a result, the roughness of flat silica film prepared at 1050$^{\circ}C$ showed 5, 6nm.

• Journal of the Korean Ceramic Society
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• v.39 no.9
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• pp.896-901
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• 2002

Since many process parameters of FHD(Flame Hydrolysis Deposition) are involved in forming multi-component amorphous silica film ($SiO_2-B_2O_3-P_2O_5-GeO_2$), it has not been easy to predict the optical, mechanical and thermal properties of deposited film from the simple process parameters, such as source flow rate. Furthermore, the prediction of final composition of film becomes even more difficult after sintering at high temperature due to the evaporation of volatile dopants. The motivation of the study was to clarify the quantitative relationship between simple process parameters such as the flow rate of source gases and resulting chemical composition of sintered film. Hence, the compositional analysis of silica soot by FTIR(Fourier Transformation Infrared Spectroscopy) and ICP-AES(Inductively Coupled Plasma-Atomic Emission Spectrometry) under the control of the amount of dopant was carried out to obtain the quantitative composition. By measuring spectrum of absorbance from FTIR, the compositional change of B-O, Si-O, OH($H_2O$) in silica film was measured. The concentrations of these dopants were also measured by ICP-AES, which were compared with the FTIR result. The final quantitative relationship between simple process parameters and composition was deduced from the comparison between two results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.11
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• pp.1464-1469
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• 2000

The effects of SiCl$_4$addition on flame structures have been studied in flame hydrolysis deposition (FHD) processes using Coherent anti-Stokes Raman spectroscopy (CARS) and planar laser induced fluorescence (PLIF) to measure temperatures and OH concentrations, respectively. The results demonstrate that even a small amount of SiCl$_4$ addition can change thermal and chemical structures of H$_2$/O$_2$ diffusion flames. When SiCl$_4$ is added to a flame temperature decreases in non-reacting zone due to the increases in both specific heat and density of the gas mixture, while flame temperature increase in particle formation zone due to the heat release through hydrolysis and oxidation reactions of SiCl$_4$. It is also found that OH concentration decreases dramatically in particle formation zone where temperatures increase. This can be attributed to consumption of oxidative species and generation of HCl during silica formation.

• Journal of the Korean Ceramic Society
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• v.40 no.6
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• pp.589-593
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• 2003

Silica based Planar Lightwave Circuits (PLC) have been applied to various kinds of wave-guided optical passive devices. SiO$_2$ (buffer) and GeO$_2$-SiO$_2$ (core) thick films have been deposited by Flame Hydrolysis Deposition (FHD). The SiO$_2$ films were produced by the flame hydrolysis reaction of halide materials such as SiCl$_4$, POCl$_3$ and BCl$_3$ into an oxy-hydrogen torch. The P concentration increased from 2.0 to 2.8 at％ on increasing the POCl$_3$/BCl$_3$ flow ratio. The refractive index increased from 1.4584 to 1.4605 on increasing the POC1$_3$/BC1$_3$ flow ratio from 0.6 to 2.6. The refractive index of GeO$_2$-SiO$_2$ films was controlled by the GeCl$_4$ flow rate. The refractive index increased from 1.4615 to 1.4809 on increasing the GeCl$_4$ flow rate from 30 to 120 sccm.

• Journal of the Korean Ceramic Society
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• v.38 no.12
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• pp.1144-1149
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• 2001

In this research, the fabrication of Si/SiO$_2$optical waveguide amplifier by FHD(Flame Hydrolysis Deposition) and Solution Doping was carried out. It was observed that the reduction of fluorescence was prevented up to 0.14 wt% Er whn 0.48 wt% Al was doped and the FWHA of $1.5mutextrm{m}$ fluorescence band increased by 5 nm as increasing amount of Al. Therefore from these results, we could confirm depressing concentration quenching of Er ions and increasing FWHM of fluorescence spectrum by addition of Al.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.46-47
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• 2002

Flame Hydrolysis Deposition (FHD) 공정은 SiC1$_4$, GeCl$_4$, POC1$_3$, BCl$_3$ 등의 원료를 사용하여 Si wafer 및 유리기판 위에 silicate soot를 증착하는 방법이며, 증착된 soot는 고온에서 소결과정을 거쳐 B$_2$O$_3$-P$_2$O$_{5}$ -GeO$_2$-SiO$_2$(BPGS)계 유리막으로 형성된다. 유리막의 굴절률은 SiC1$_4$, GeCl$_4$, POC1$_3$, BCl$_3$ 등의 원료 유량을 조절하여 변화가능하며 이를 이용하여 광도파로를 제작할 수 있다 특히 광통신에 사용할 수 있는 광증폭기 등의 능동형 광소자 제작을 위해서는 FHD공정을 통해 형성된 soot에 Er$^{3+}$ 등의 희토류 원소를 첨가하여야 한다. (중략)

• Korean Journal of Optics and Photonics
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• v.16 no.4
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• pp.340-344
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• 2005

Microlens cells of Ge-doped BPSG (Boro-Phospho-Silicate Glass) are fabricated by dicing the film produced by FHD (Flame Hydrolysis Deposition). Microlens arrays of $53.4{\mu}m$ square unit are produced by the thermal reflow of the diced unit cells at $1200^{\circ}C$. The gap between the microlenses was about $70{\mu}m,$ and the thickness of the produced lens was about $28.4{\mu}m$. We analyzed the reflowed shape of the microlens cell by an image-process technique, and the focal length was about $62.2{\mu}m$. This method of fabricating a microlens is simple and inexpensive compared to the conventional method using the photolithographic process. Also, the control of the radius of curvature of the microlens is easier and a more precise microlens way of various types can be fabricated using this method.