• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.5
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• pp.393-397
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• 2002

Polyimide (PI) films have been studied widely as the interlayer dielectric materials due to a low dielectric constant, low water absorption, high gap-fill and planarization capability. The polyimide film was etched using inductively coupled plasma system. The etcying characteristics such as etch rate and selectivity were evaluated at different $CF_4/(CF_4+O_2)$chemistry. The maximum etch rate was 8300 ${\AA}/min$ and the selectivity of polyimide to SiO$_2$was 5.9 at $CF_4/(CF_4+O_2)$ of 0.2. Etch profile of polyimide film with an aluminum pattern was measured by a scanning electron microscopy. The vertical profile was approximately $90^{\circ}$ at $CF_4/(CF_4+O_2)$ of 0.2. As 20% $CF_4$ were added into $O_2$ plasma from the results of the optical emission spectroscopy, the radical densities of fluorine and oxygen increased with increasing $CF_4$ concentration in $CF_4/O_2$ from 0 to 20%, resulting in the increased etch rate. The surface reaction of etched PI films was investigated using x-ray photoelectron spectroscopy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.137-140
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• 2003

Cu+ ions drift diffusion in different dielectric materials is evaluated. The diffusion is investigated by measuring shift in the flatband voltage of capacitance/voltage measurements on Cu gate capacitors after bias temperature stressing. At a field of 1.lMV/cm and temperature $200^{\circ}C$, $250^{\circ}C$, $300^{\circ}C$ for 1H, 2H, 5H. The Cu+ ions drift rate of polyimide$(2.8{\leq}k{\leq}3.2)$ is considerably lower than thermal oxide. Also Cu+ drift rate of polyimide is similar to PECVD oxide. But, polyimide film is even more resistant to Cu drift diffusion and thermal effect than Thermal oxide, PECVD oxide: This results got a comparative reference. The important conclusion is that polyimide film is strongly dielectric material by thermal effect and Cu drift diffusion.

• Macromolecular Research
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• v.17 no.8
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• pp.568-574
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• 2009

We investigated the sintering and consolidation phenomena of silver nanoparticles under various thermal treatment conditions when they were patterned by a contact printing technique on polyimide substrate films. The sintering of metastable silver nanoparticles commenced at 180 $^{\circ}C$, where the point necks were formed at the contact points of the nanoparticles to reduce the overall surface area and the overall surface energy. As the temperature was increased up to 250 $^{\circ}C$, silver atoms diffused from the grain boundaries at the intersections and continued to deposit on the interior surface of the pores, thereby filling up the remaining space. When the consolidation temperature exceeded 270 $^{\circ}C$, the capillary force between the spherical silver particles and polyimide flat surface induced the permanent deformation of the polyimide films, leaving crater-shaped indentation marks. The bonding force between the patterned silver metal and polyimide substrate was greatly increased by the heat treatment temperature and the mechanical interlocking by the metal particle indentation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.6
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• pp.594-597
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• 2023

We have proposed and demonstrated a fiber optic RH (relative humidity) sensor based on fiber Bragg grating covered with a polyimide film. As the polyimide film absolves the moisture in the air, its volume expands. As a result, the grating period of the FBG (fiber Bragg grating) covered with a polyimide film becomes wide and the Bragg wavelength is shifted. The sensor is implemented by fixing a 30 ㎛ thickness polyimide film on the surface of an optical fiber grating using an adhesive, and the characteristics of the device according to humidity are analyzed. The fabricated FBG RH sensor showed a high sensitivity of 0.0186 nm/RH% and a wide measurement range from 30% to 90%. The influence of environmental temperature on the characteristics of the RH sensor was also measured and analyzed. The feasibility of commercialization is presented.

• Polymer(Korea)
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• v.24 no.2
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• pp.228-236
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• 2000

The preparation of organophilic clay from Na$^{+}$-MMT was achieved by intercalation of alkylammonium bromide. The dispersed organophilic clay in NMP was then added to the solution of polyamic acids (BPDA-PPD, BTDA-ODA/ MPD) in NMP. After curing at 30$0^{\circ}C$, thin films of the polyimide/clay nanocomposite were prepared. The results of X-ray diffraction (XRD) shelved that the d-spacings of dried polyamic acid (PAA)-clay complexes increased in proportion to the chain length of the onium ion and patterns of two kinds of PAA-clay complexes were similar. The d-spacings of approximately 13.2 $\AA$ for the polyimide/clay nanocomposites were independent of the initial onium ion chain length and the species of PAA. From the study of XRD and transmission electron microscopy (TEM), we found layered silicates were dispersed in polyimide matrix and the resultants were intercalated nanocomposites. TGA result showed thermal stability of polyimide nanocomposite improved a little more than the pure polyimide. From the result of dynamic mechanical property, we found that the storage modulus of the nanocomposites had increased by 1.2-1.8 times of the pure polyimides.s.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.3 s.36
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• pp.207-212
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• 2005

Al, Ti, Ta, and Cr thin films were deposited on a polyimide substrate using DC magnetron sputter to study the adhesion characteristics of metal films on polyimide substrates, while RF bias of 0 - 400 W was applied to the substrate during DC sputtering. The adhesion strength was evaluated using a 90-degree peel test. The peel tests showed that the adhesion strength was enhanced by applying the RF bias to the substrate in all specimens. Scanning electron microscopy and Auger depth profile of the fractured surfaces indicate that the polyimide underwent cohesive failure during peeling and heavy deformation was also observed in the metal films peeled from the polyimide substrate when the RF bias applied during the deposition. Cross-sectional transmission electron microscopy revealed that the metal/polyimide interface was not clear and complicated. This complicated interface, likely formed due to the RF bias applied to the substrate, was attributed to the adhesion enhancement observed during the bias sputtering.

• Polymer(Korea)
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• v.27 no.5
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• pp.484-492
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• 2003

How the characteristics and stability of the rubbing-induced alignment of nematic liquid crystals (LCs) relate to the interfacial characteristics of LC-polyimide has been studied. The characteristics of the LC alignment (such as the LC texture, the pretilt angle, and the anchoring energy) and their thermal stability have been investigated for 5 polyimides synthesized for this work. The work showed that the rubbed polyimide alignment layer induces the strong LC anchoring and that the characteristics and stability of LC alignment are determined by the short-ranged interactions between LC and polyimide molecules at the alignment layer surface. The increased flexibility of the polyimide accelerates thermal imidization, increases the pretilt angle, and improves the alignment stability. It also turned out that fluorination of the polyimide tends to deteriorate the alignment uniformity and stability. No distinct differences in the alignment characteristics were shown for the aromatic- and alicyclic-dianhydride polyimides.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.162-163
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• 2008

이 논문에서는 Polyimide 기판의 $O_2$ 플라즈마 처리효과에 따른 GZO 박막의 구조적, 전기적, 광학적인 특성을 고찰하였다. ICP-RIE 방법을 이용하여 Polyimide 기판의 $O_2$ 플라즈마 처리의 변수로 RF power와 처리시간을 각 100 ~ 400 W, 120 ~ 600 초까지 조절하였다. RF 스퍼터링 방법으로 $O_2$ 플라즈마 처리효과에 따른 Polyimide 기판을 4인치의 GZO(ZnO : 95 wt%, $Ga_2O_3$ 5 wt%) 타겟을 사용하여 RF power 90 W, 공정압력 5 mTorr, Ar gas 20 sccm, 기판거리 5 cm, 박막두께 500nm, 상온의 조건으로 GZO 박막을 증착 하였다. Polyimide 기판에 $O_2$ 플라즈마 처리를 하지 않고 증착한 GZO 박막의 비저황은 $1.02\times10^{-2}\Omega$-cm 이었고 RF power 100W, 처리시간 120 초로 $O_2$ 플라즈마 처리 후에 증착한 GZO 박막의 비저항이 $1.89\times10^{-3}\Omega$-cm인 최적의 값이 측정되었으며 RF power가 증가할수록 투과도는 감소하였지만 처리시간의 변화에 따라서는 투과도 변화가 거의 없었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.170-170
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• 2000

Synthetic polymers such as polyimide, polycarbonate, and poly(methyl methacrylate) are long chain molecules which consist of carbon, hydrogen, and heteroatom linked together chemically. Recently, polymer surface can be modified by using a high energy ion beam process. High energy ions are introduced into polymer structure with high velocity and provide a high degree of chemical bonding between molecular chains. In high energy beam process the modified polymers have the highly crosslinked three-dimensionally connected rigid network structure and they showed significant improvements in electrical conductivity, in hardness and in resistance to wear and chemicals. Polyimide films (Kapton, types HN) with thickness of 50~100${\mu}{\textrm}{m}$ were used for investigations. They were treated with two different surface modification techniques: Plasma Source Ion Implantation (PSII) and conventional Ion Implantation. Polyimide films were implanted with different ion species such as Ar+, N+, C+, He+, and O+ with dose from 1 x 1015 to 1 x 1017 ions/cm2. Ion energy was varied from 10keV to 60keV for PSII experiment. Polyimide samples were also implanted with 1 MeV hydrogen, oxygen, nitrogen ions with a dose of 1x1015ions/cm2. This work provides the possibility for inducing conductivity in polyimide films by ion beam bombardment in the keloelectronvolt to megaelectronvolt energy range. The electrical properties of implanted polyimide were determined by four-point probe measurement. Depending on ion energy, doses, and ion type, the surface resistivity of the film is reduced by several orders of magnitude. Ion bombarded layers were characterized by Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS), XPS, and SEM.

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.05a
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• pp.19-19
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• 1999