• Proceedings of the KSME Conference
• /
• 2008.11b
• /
• pp.2369-2374
• /
• 2008

In the precision hot plate for wafer processing, the temperature uniformity of upper plate surface is one of the key factors affecting the quality of wafers. Precision hot plates require temperature variations less than ${\pm}1.5%$ during heating to $120^{\circ}C$. In this study, we have manufactured the flat plate heat pipe hot chuck of circle type(300mm) and investigated the operating characteristics of flat plate heat pipe hot chuck experimentally. Various liquids(aceton, FC-40, water) were used as the working fluid and charging ratio was changed($14{\sim}36\;vol.%$). Several cases were tested to improve temperature uniformity. Major working fluid to be investigated was water. Using water, various parameters such as charging ratio, wafer operation on-off time, different working fluids. In case of water, the temperature uniformity was ${\pm}1.5%$, response time of wafer were investigated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.15 no.6
• /
• pp.479-485
• /
• 2002

We have investigated the effects of various wafers cleaning on glass/Si bonding using 4 inch Pyrex glass wafers and 4 inch silicon wafers. The various wafer cleaning methods were examined; SPM(sulfuric-peroxide mixture, $H_2SO_4:H_2O_2$ = 4 : 1, $120^{\circ}C$), RCA(company name, $NH_4OH:H_2O_2:H_2O$ = 1 : 1 : 5, $80^{\circ}C$), and combinations of those. The best room temperature bonding result was achieved when wafers were cleaned by SPM followed by RCA cleaning. The minimum increase in surface roughness measured by AFM(atomic force microscope) confirmed such results. During successive heat treatments, the bonding strength was improved with increased annealing temperatures up to $400^{\circ}C$, but debonding was observed at $450^{\circ}C$. The difference in thermal expansion coefficients between glass and Si wafer led debonding. When annealed at fixed temperatures(300 and $400^{\circ}C$), bonding strength was enhanced until 28 hours, but then decreased for further anneal. To find the cause of decrease in bonding strength in excessively long annealing time, the ion distribution at Si surface was investigated using SIMS(secondary ion mass spectrometry). tons such as sodium, which had been existed only in glass before annealing, were found at Si surface for long annealed samples. Decrease in bonding strength can be caused by the diffused sodium ions to pass the glass/si interface. Therefore, maximum bonding strength can be achieved when the cleaning procedure and the ion concentrations at interface are optimized in glass/Si wafer direct bonding.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.11 no.6
• /
• pp.48-54
• /
• 2012

In recent years, developments in the semiconductor and electronic industries have brought a rapid increase in the use of large size silicon. However, for many companies, it is hard to produce 400mm or 450mm wafers, because of excesive funds for exchange the equipments. Therefore, it is necessary to investigate 300mm wafer to obtain a better efficiency and a good property rate. Polishing is one of the important methods in manufacturing of Si wafers and in thinning of completed device wafers. This research investigated the surface characteristics that apply variable machining conditions and Taguchi Method was used to obtain more flexible and optimal condition. In this study, the machining conditions have head speed, oscillation speed and polishing time. By using optimum condition, it achieves a ultra precision mirror like surface.

• Journal of Powder Materials
• /
• v.28 no.1
• /
• pp.25-30
• /
• 2021

The surface of silicon dummy wafers is contaminated with metallic impurities owing to the reaction with and adhesion of chemicals during the oxidation process. These metallic impurities negatively affect the device performance, reliability, and yield. To solve this problem, a wafer-cleaning process that removes metallic impurities is essential. RCA (Radio Corporation of America) cleaning is commonly used, but there are problems such as increased surface roughness and formation of metal hydroxides. Herein, we attempt to use a chelating agent (EDTA) to reduce the surface roughness, improve the stability of cleaning solutions, and prevent the re-adsorption of impurities. The bonding between the cleaning solution and metal powder is analyzed by referring to the Pourbaix diagram. The changes in the ionic conductivity, H2O2 decomposition behavior, and degree of dissolution are checked with a conductivity meter, and the changes in the absorbance and particle size before and after the reaction are confirmed by ultraviolet-visible spectroscopy (UV-vis) and dynamic light scattering (DLS) analyses. Thus, the addition of a chelating agent prevents the decomposition of H2O2 and improves the life of the silicon wafer cleaning solution, allowing it to react smoothly with metallic impurities.

• Clean Technology
• /
• v.18 no.1
• /
• pp.43-50
• /
• 2012

Cleaning procedure of solar silicon wafer, following ingot sawing process in solar cell production is studied. Types of solar silicon wafer can be divided into monocrystalline or multicrystalline, and slurry sawn wafer or diamond sawn wafer according to the ingot growing methods and the sawing methods, respectively. Wafer surface and contaminants can vary with these methods. The characterisitics of contaminants and wafer surface are investigated for each cleaning substrate, and appropriate cleaning agents are developed. Physical properties and cleaning ability of the cleaning agents are evaluated in order to verify the application in the industry. The wafers cleaned with the cleaning agents do not show any residual contaminants when analyzed by XPS and regular patterns are formed after texturization. Furthermore, the cleaning agents are applied in the production industry, which shows superior cleaning results compared to the existing cleaning agents.

• Journal of the Korean Society for Precision Engineering
• /
• v.29 no.3
• /
• pp.289-294
• /
• 2012

There are several indicators to represent characteristics of chemical mechanical planarization (CMP) such as material removal rate (MRR), surface quality and removal uniformity on a wafer surface. Especially, the removal uniformity on the wafer edge is one of the most important issues since it gives a significant impact on the yield of chip production on a wafer. Non-uniform removal rate at the wafer edge (edge effect) is mainly induced by a non-uniform pressure from nonuniform pad curvature during CMP process, resulting in edge exclusion which means the region that cannot be made to a chip. For this reason, authors tried to minimize the edge exclusion by using an edge profile control (EPC) ring. The EPC ring is equipped on the polishing head with the wafer to protect a wafer from the edge effect. Experimental results showed that the EPC ring could dramatically minimize the edge exclusion of the wafer. This study shows a possibility to improve the yield of chip production without special design changes of the CMP equipment.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.36 no.10
• /
• pp.1241-1248
• /
• 2012

The objective of this study is to evaluate the thermal damage characterization of a silicon wafer subjected to a CW laser beam. The variation in temperature and stress during laser beam irradiation has been predicted using a three-dimensional numerical model. The simulation results indicate that the specimen might crack when a 93-$W/cm^2$ laser beam is irradiated on the silicon wafer, and surface melting can occur when a 186-$W/cm^2$ laser beam is irradiated on the silicon wafer. In experiments, straight cracks in the [110] direction were observed for a laser irradiance exceeding 102 $W/cm^2$. Furthermore, surface melting was observed for a laser irradiance exceeding 140 $W/cm^2$. The irradiance for surface melting is less than that in the simulation results because multiple reflections and absorption of the laser beam might occur on the surface cracks, increasing the absorbance of the laser beam.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.3 no.2
• /
• pp.74-79
• /
• 2002

In the a rapid changes of the semiconductor manufacturing technologies for early 21st century, it may be safely said that a kernel of terms is the size increase of Si wafer and the size decrease of semiconductor devices. As the size of Si wafers increases and semiconductor device is miniaturized, the units of cleaning processes increases. A present cleaning technology is based upon RCA cleaning which consumes vast chemicals and ultra pure water (UPW) and is the high temperature process. Therefore, this technology gives rise to the environmental issue. To resolve this matter, candidates of advanced cleaning processes has been studied. One of them is to apply the electrolyzed water. In this work, Compared with surface on Si wafer with electrolyzed water cleaning and various chemicals cleaning, and analyzed Si wafer surface condition treated with elecoolyzed water by cleaning temperature and cleaning time. Especially. concentrate upon the contact angle. finally, contact angle on surface treated with cathode water cleaning is 17.28, and anode water cleaning is 34.1.

• Journal of the Korean Vacuum Society
• /
• v.6 no.1
• /
• pp.9-19
• /
• 1997

The reaction mechanisms of dry cleaning with UV-excited chlorine radical for Zn, Fe and Ti trace contaminants on the Si wafer have been studied by SEM, AFM and XPS analyses in this work. The patterned Zn, Fe and Ti films were deposited on the Si wafer surface by thermal evaporation and changes in the surface morphology after dry cleaning with $Cl_2$and UV/$Cl_2$at $200^{\circ}C$ were studied by optical microscopy and SEM. In addition, changes in the surface roughness of Si wafer with the cleaning was observed by AFM. The chemical bonding states of the Zn, Fe and Ti deposited silicon surface were observed with in-line XPS analysis. Zn and Fe were easily cleaned in the form of volatile zinc-chloride and iron-chloride as verified by the surface morphology changes. Ti which forms involatile oxides was not easily removed at room temperature but was slightly removed by UV/$Cl_2$at elevated temperature of $200^{\circ}C$. It was also found that the surface roughness of the Si wafer increased after $Cl_2$and UV/$Cl_2$cleaning. Therefore, the metallic contaminants on the Si wafer can be easily removed at lower temperature without surface damage by a continuous process using wet cleaning followed by UV/$Cl_2$dry cleaning.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.15 no.1
• /
• pp.34-38
• /
• 2005

Effects of pH level and slurry particle size on material removal rate and planarization of langasite single crystal wafer have been examined. Higher material removal rate was obtained with lower pH level slurries while the planarization was found to be determined by average particle size of colloidal silica slurries. Slurries containing 0.045 ㎛ amorphous silica particles showed the best polishing effect without any scratches on the surface. Effective particle number has a strong effect on the surface planarization and the removal rate, so that the lower effective particle numbers produced low removal rate but the better planarization results.