• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07a
• /
• pp.310-313
• /
• 2002

Structures obtained with a direct boning of two FZ silicon wafers joined in such a way that a smooth surface of one wafer was attached to the grooved surface of the other were studied. A square net of grooves was made with a conventional photo lithography process. After high temperature annealing the appearance of voids and the rearrangement of structural defects were observed with X-ray diffraction topography techniques. It was shown that the formation of void free grooved boundaries was feasible. In the cases when particulate contamination was prevented, the voids appeared in the grooved structures could be eliminated with annealing. Since it was found that the flattening was accompanied with plastic deformation, this deformation was suggested to be intensively involved in the process of void removal. A model was proposed explaining the interaction between the structural defects resulted in "a dissolution" of cavities. The described processes may occur in grooved as well as in smooth structures, but there are the former that allow to manage air traps and undesirable excess of dislocation density. Grooves can be paths for air leave. According to the established mechanisms, if not outdone, the dislocations form local defect arrangements at the grooves permitting the substantial reduction in defect density over the remainder of the interfacial area.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07a
• /
• pp.32-35
• /
• 2002

The work focuses on the development of a Cu lead-frame with a single-sided adhesive tape for cost reduction and reliability improvement of LOC (lead on chip) package products, which are widely used for the plastic-encapsulation of memory chips. Most of memory chips are assembled by the LOC packaging process where the top surface of the chip is directly attached to the area of the lead-frame with a double-sided adhesive tape. However, since the lower adhesive layer of the double-sided adhesive tape reveals the disparity in the coefficient of thermal expansion from the silicon chip by more than 20 times, it often causes thermal displacement-induced damage of the IC pattern on the active chip surface during the reliability test. So, in order to solve these problems, in the resent work, the double-sided adhesive tape is replaced by a single-sided adhesive tape. The single-sided adhesive tape does net include the lower adhesive layer but instead, uses adhesive materials, which are filled in clear holes of the base film, just for the attachment of the lead-frame to the top surface of the memory chip. Since thermal expansion of the adhesive materials can be accommodated by the base film, memory product packaged using the lead-flame with the single-sided adhesive tape is shown to have much improved reliability. Author allied this invention to the Korea Patent Office for a patent (4-2000-00097-9).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.20 no.10
• /
• pp.912-917
• /
• 2007

Many electrochemical power devices such as solid state batteries and solid oxide fuel cell have been studied and developed for solving energy and environmental problems. An amperometric gas sensor usually generates sensing signal of electric current along the proportion of the concentration of target gas under the condition of limiting current. For narrow variations of gas concentration, the amperometric gas sensor can show higher precision than a potentiometric gas sensor does. In additional, cross sensitivities to interfering gases can possibly be mitigated by choosing applied voltage and electrode materials properly. In order to improve the sensitivity to $NO_2$, the device was attached with Au reference electrode to form the amperometric gas sensor device with three electrodes. With the fixed bias voltage being applied between the sensing and counter electrodes, the current between the sensing and reference electrodes was measured as a sensing signal. The response to $NO_2$ gas was obviously enhanced and suppressed with a positive bias, respectively, while the reverse current occurred with a negative bias. The way to enhance the sensitivity of $NO_2$ gas sensor was thus realized. It was shown that the response to $NO_2$ gas could be enhanced sensitivity by changing the bias voltage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.181-181
• /
• 2010

Few-walled carbon nanotubes (FWNTs)-based field emitters with long term stability are fabricated by using a spray method. Tetraethylorthosilicate (TEOS) sol as a binder was mixed with dispersed solution of FWNTs to enhance the adhesion of FWNTs on the cathode substrate. Due to the strong intermolecular interaction of TEOS to the functional groups attached on CNTs and substrate, CNTs are tightly adhered to the cathode electrode when heat treatment is performed at $150^{\circ}C$ for 1 hour, resulting in a stable electron emission of CNT emitters for long time. Excellent field emission characteristics were exhibited, with a large field enhancement factor and low turn-on voltage, comparable to those of CNT emitters fabricated by a screen printing of CNT paste. Therefore, FWNTs / TEOS hybrid films could be utilized as an alternative for the efficient and reliable field emitters.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.318-318
• /
• 2010

In this paper, we studied generating characteristic of cymbal type piezoelectric transducer according to change of cymbal cap. The transducer is composed of circular piezoelectric ceramic and two elastic bodies which are shaped as cymbal. Two elastic bodies are attached to upper and bottom of the ceramic. Principle of the transducer is to generate expanded displacement because vertical stress is transformed into horizontal stress by slope angle of elastic bodies. The transducer also has advantage of high durability by the angle of elastic bodies. In this study, each parameter was chosen, and then generating characteristics were analyzed by FEM program. The parameters were slope angle of cymbal cap (theta), cap height (h) and cap inner diameter(d). The model that had generating characteristic Of high voltage was chosen by results of the analysis. Besides, maximum vertical displacements according to change of vertical stress were analyzed by structural analysis in order to find out relation between the maximum vertical stress which can prevent from ceramic damage and conditions of each cap.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.319-319
• /
• 2010

The previous cross type USM(ultrasonic motor) has the stator of cross shape composed of 8 ceramics. However, ultrasonic motor with simple structure has the stator composed of only 4 ceramics. Principle of the motor is to apply alternative voltages which have 90 phase difference to attached ceramics, and then elliptical displacement is generated at four edges of elastic body. Characteristics of the motor were simulated by FEM(finite element method). The parameters were size of the stator and thickness of the ceramics. According to FEM results, driving frequency of motor is defined at 28 [kHz]. On the contrary, driving frequency of fabricated motor is defined at 26.8 [kHz] and then, experimental results were compared with FEM results at the frequency. As a result, elliptical displacement and speed of USM increased linearly with increasing applied voltage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.320-320
• /
• 2010

In the case of existing ultrasonic motors, they have characteristics such as outstanding response speed, speed and high efficiency. However, it's very hard to use practically them as small motors due to complicated structure and expensive cost. This paper proposed v-type ultrasonic linear motor. Stator of the motor is composed of thin elastic body and four ceramics attached to upper and bottom areas of the body. The ceramics have each direction of polarization. When two harmonic voltages which had $90^{\circ}$ phase difference were applied to the ceramics, the symmetric and anti-symmetric displacements were generated at the tip to make the elliptical motion. To find out a model that generates maximum displacement at contact tip, FEM program was used with change of leg-angle. In addition, optimal model was chosen by considering magnitude and shape of displacement according to change of frequency.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.148-148
• /
• 2008

Low-k dielectric materials are an alternative plan to improve the signal propagation delay, crosstalk, dynamic power consumption due to resistance and parasitic capacitance generated the decrease of device size. Now, various materials is studied for the next generation. Diethoxymethlysiliane (DEMS) precursor using this study has two ethoxy groups along with one methyl group attached to the silicon atoms. SiCOH thin films were deposited on p-type Si(100) substrate by Plasma Enhanced Chemical Vapor Deposition (PECVD) using DEMS. In this study, we studied the effect of oxygen($O_2$) flow rate for DEMS to characteristics of thin films. The characteristics of thin films deposited using DEMS and $O_2$ evaluated through refractive index, dielectric constant(k), surface roughness, I-V(MIM:Al / SiCOH / Ag), C-V(MIM), deposition rate.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.10
• /
• pp.1107-1113
• /
• 2004

Dry film method for large size of PDP(Plasma Display Panel) module has been actively investigated. This method for lead-free transparent dielectric formation depends on green sheet technology. By adjusting the composition of transparent dielectric powders and organics, uniformly dispersed slurry was fabricated, Viscosity of the slurry exhibited pseudoplastic behavior for tape casting, Cast green sheets were tested under tensile condition at room temperature. It was found that the increase in transparent dielectric powder and binder ratio leads to decrease in strain to failure of green sheets from 120 % to 34 % and from 255 % to 4 %, respectively. Tensile strength of green sheets decreased abruptly with increase of transparent dielectric powder ratio, with minimum at 0.13 MPa. On the other hand, tensile strength increased continuously from 0.1 MPa to 2.4 MPa with increase of binder ratio. The green sheets were attached on the glass substrate and heated by following firing schedule. As a result, the best result was obtained when fired at 580 $^{\circ}C$ for 15 min and had transmittance of 78 % in visible range 550 nm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.08a
• /
• pp.12-14
• /
• 2003

As the integrated circuit device shrinks to the smaller dimension, the chemical mechanical polishing (CMP). process was required for the global planarization of inter-metal dielectric (IMD) layer with free-defect. However, as the IMD layer gets thinner, micro-scratches are becoming as major defects. Micro-scratches are generated by agglomerated slurry, solidified and attached slurry in pipe line of slurry supply system. It is well known that the presence of hard and larger size particles in the CMP slurries increases the defect density and surface roughness of the polished wafers. In this paper, we have studied. aging effect the of CMP slurry as a function of particle size. We prepared and compared the self-developed silica slurry by adding of abrasives before and after annealing. As our preliminary experiment results, we could be obtained the relatively stable slurry characteristics comparable to original silica slurry in the slurry aging effect.