• 한국가스학회:학술대회논문집
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• 2003.05a
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• pp.69-74
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• 2003

• Bulletin of the Korean Chemical Society
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• v.15 no.6
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• pp.428-432
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• 1994

The crystals of ${\beta}-and\;{\beta}'-(ET)_2ICl_2$ have a modified structure of organic superconductor ${\beta}(ET)_2I_3$. These salts possess strictly different physical properties : the ${\beta}$ phase is a metal but the ${\beta}'$ phase is a semiconductor. Our band electronic structure calculations show that the ${\beta}$ phase is somewhat anisotropic 2D metal and the ${\beta}'$ phase with the 1D character in electronic structure is magnetic insulating, in good agreement with experimental indications.

• Bulletin of the Korean Chemical Society
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• v.11 no.5
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• pp.464-466
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• 1990

A ternary Zintl phase material of the formula $K_2Ga_2Sb_4$ has been prepared directly from reaction of the elements following a high temperature procedure. The compound consists of potassium ions and planar ribbons of $(Ga_2Sb_4^{-2})_{\infty}$ consisting of five membered $[Ga_2Sb_3]$ rings bridged by Sb atoms. The variable temperature specific resistivity measurements show the material to be an intrinsic semiconductor.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.1
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• pp.5-14
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• 2023

In this study, LiDAR-reflective black hollow-structured silica/titania(B-HST) materials are successfully synthesized by employing the NaBH₄ reduction and etching method on silica/titania core/shell(STCS) materials, which also effectively enhance near-infrared(NIR) reflectance. Moreover, core-etched supernatant solutions are collected and recycled for the synthesis of extracted silica(e-SiO₂) process, which successfully applies as filler materials for semiconductor epoxy molding compound(EMC). In detail, B-HST materials, fabricated by the sequential experimental steps of sol-gel, reduction, and sonication-mediated etching method, manifest blackness(L^*) of 13.2 similar to black paint and excellent NIR reflectance(31.1%). Consequently, B-HST materials are successfully prepared as LiDAR-reflective black materials. Additionally, core-etched supernatant solution with silanol precursors are employed for synthesis of homogeneous silica filler materials via sol-gel method. As-synthesized silica fillers are incorporated with epoxy resin and carbon black for the preparation of semiconductor EMC. Experimentally synthesized EMC exhibits comparable mechanical-chemical properties to commercial EMC. Conclusively, this study successfully proposes designing procedure and practical experimental method for simultaneously synthesizing the NIR-reflective black materials for self-driving vehicles and EMC materials for semiconductors, which are materials suitable for the industrial 4.0 era, and presented their applicability in future industries.

• Journal of the Korean Chemical Society
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• v.54 no.5
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• pp.594-602
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• 2010

Since the requirement of the high density integration and thin package technique of semiconductor have been increasing, the main package type of semiconductor will be a chip scale package (CSP). The changes of diffusion coefficient and moisture content ratio of epoxy resin systems according to the change of liquid type epoxy resin and fillers for CSP applications were investigated. The epoxy resins used in this study are RE-304S, RE310S, and HP-4032D, and Kayahard MCD as hardener and 2-methylimidazole as catalyst were used in these epoxy resin systems. The micro-sized and nano-sized spherical type fused silica as filler were used in order to study the moisture absorption properties of these epoxy molding compound (EMC) according to the change of filler size. The temperature of glass transition (Tg) of these EMC was measured using Dynamic Scanning Calorimeter (DSC), and the moisture absorption properties of these EMC according to the change of time were observed at $85^{\circ}C$ and 85% relative humidity condition using a thermo-hygrostat. The diffusion coefficients in these EMC were calculated in terms of modified Crank equation based on Ficks' law. An increase of diffusion coefficient and maximum moisture absorption ratio with Tg in these systems without filler can be observed, which are attributed to the increase of free volume with Tg. In the EMC with filler, the changes of Tg and maximum moisture absorption ratio with the filler content can be hardly observed, however, the diffusion coefficients of these systems with filler content show the outstanding changes according to the filler size. The diffusion via free volume is dominant in the EMC with micro-sized filler; however, the diffusion with the interaction of absorption according the increase of the filler surface area is dominant in the EMC with nano-sized filler.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.1 no.2
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• pp.33-40
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• 2000

The present invention relates to a absorption rotor for removed VOC(volatile organic compound) and humidity in semiconductor clean room system. A absorption rotor medium is made by NaX zeolite and TS-1 zeolite formed on a honeycomb matrix of ceramic papers. The crystallization of NaX zeolite was hydrothermal reaction, and NaX zeolite crystals of a uniform particle size of 5$\mu$m were synthesized that NaX zeolite seed crystals (2~3$\mu$m) added in a batch composition at levels of 3~15 wt$\%$. The seeding resulted in an increase in the fraction of large crystals compared with unseeded batches and successfully led to a uniform NaX zeolite crystal. The microporous zeolite-type titanosilicate(TS-1) was synthesized by different of the reactant solution pH. The pH range of reactant solution has been changed from 10.0 to 11.5 TS-1 zeolite (ETS-10), having a large pore(8~10 $\AA$), was synthesized at 10.4 of pH, since TS-1 zeolite (ETS-4), having a small pore(3~5$\AA$), was synthesized at 11.5 of pH.

• Korean Journal of Materials Research
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• v.13 no.7
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• pp.465-472
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• 2003

Pd/Ge/Ti/Pt and Pd/Ge/Pd/Ti/Au ohmic contacts to n-type InGaAs were investigated for applications to AlGaAs/GaAs HBT emitter ohmic contacts. In the Pd/Ge/Ti/Pt ohmic contact minimum specific contact resistivity of $3.7${\times}$10^{-6}$ $\Omega$$\textrm{cm}^2$ was achieved by rapid thermal annealing at $^400{\circ}C$/10 sec. In the Pd/Ge/Ti/Au ohmic contact, minimum specific contact resistivity of $1.1${\times}$10^{-6}$ $\Omega$$\textrm{cm}^2$ was achieved by annealing at 40$0^{\circ}C$/10 sec but the ohmic performance was degraded with increasing annealing temperature due to the reaction between the ohmic contact materials and the InGaAs substrate. However, non-spiking planar interface and relatively good ohmic contact (high-$10^{-6}$ /$\Omega$$\textrm{cm}^2$) were maintained after annealing at $450^{\circ}C$/10 sec. Therefore, these thermally stable ohmic contact systems are promising candidates for compound semiconductor devices. RF performance of the AlGaAs/GaAs HBT was also examined by employing the Pd/Ge/Ti/Pt and Pd/Ge/Pd/Ti/Au systems as emitter ohmic contacts. Cutoff frequencies were 63.5 ㎓ and 65.0 ㎓, respectively, and maximum oscillation frequencies were 50.5 ㎓ and 51.3 ㎓, respectively, indicating very successful high frequency operations.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.3
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• pp.1-10
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• 2023

Recently, as the demand for high-performance computers and mobile products increases, semiconductor packages are becoming high-integration and high-density. Therefore, in order to transmit a large amount of data at once, micro bumps such as flip-chip and Cu pillar that can reduce bump size and pitch and increase I/O density are used. However, when the size of the bumps is smaller than 70 ㎛, the brittleness increases and electrical properties decrease due to the rapid increase of the IMC volume fraction in the solder joint, which deteriorates the reliability of the solder joint. Therefore, in order to improve these issues, a layer that serves to prevent diffusion is inserted between the UBM (Under Bump Metallization) or pillar and the solder cap. In this review paper, various studies to improve bonding properties by suppressing excessive IMC growth of micro-bumps through additional layer insertion were compared and analyzed.

• Journal of the Semiconductor & Display Technology
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• v.17 no.4
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• pp.42-45
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• 2018

As The semiconductor decrease from 10 nanometer to 7 nanometer, It is suggested that "More than Moore" is needed to follow Moore's Law, which has been a guide for the semiconductor industry. Fan-Out Wafer Level Package(FOWLP) is considered as the key to "More than Moore" to lead the next generation in semiconductors, and the reasons are as follows. the fan-out WLP does not require a substrate, unlike conventional wire bonding and flip-chip bonding packages. As a result, the thickness of the package reduces, and the interconnection becomes shorter. It is easy to increase the number of I / Os and apply it to the multi-layered 3D package. However, FOWLP has many issues that need to be resolved in order for mass production to become feasible. One of the most critical problem is the warpage problem in a process. Due to the nature of the FOWLP structure, the RDL is wired to multiple layers. The warpage problem arises when a new RDL layer is created. It occurs because the solder ball reflow process is exposed to high temperatures for long periods of time, which may cause cracks inside the package. For this reason, we have studied warpage in the FOWLP structure using commercial simulation software through the implementation of the reflow process. Simulation was performed to reproduce the experiment of products of molding compound company. Young's modulus and poisson's ratio were found to be influenced by the order of influence of the factors affecting the distortion. We confirmed that the lower young's modulus and poisson's ratio, the lower warpage.

• Journal of the Korea Organic Resources Recycling Association
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• v.32 no.1
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• pp.21-29
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• 2024

In this study, EMC(Epoxy molding compound) waste from the semiconductor molding process is recycled and synthesized into silica nanoparticles, which are then applied as abrasive materials contains CMP(Chemical mechanical polishing) slurry. Specifically, silanol precursor is extracted from EMC waste according to the ultra-sonication method, which provides heat and energy, using ammonia solution as an etchant. By employing as-extracted silanol via a facile sol-gel process, uniform silica nanoparticles(e-SiO₂, experimentally synthesized SiO₂) with a size of ca. 100nm are successfully synthesized. Through physical and chemical analysis, it was confirmed that e-SiO₂ has similar properties compared to commercially available SiO₂(c-SiO₂, commercially SiO₂). For practical CMP applications, CMP slurry is prepared using e-SiO₂ as an abrasive and tested by polishing a semiconductor chip. As a result, the scratches that are roughly on the surface of the chip are successfully removed and turned into a smooth surface. Hence, the results present a recycling method of EMC waste into silica nanoparticles and the application to high-quality CMP slurry for the polishing process in semiconductor packaging.