Pil-Ju Ko

Chemical mechanical planarization characteristics of WO3 thin film for gas sensing

It is important to control the microstructure and surface of films to use them in gas sensors. Chemical mechanical polishing (CMP) processing is one of the most useful methods for improving the surface roughness of films. The effects of CMP on the surface morphology of WO3 thin films prepared by the rf sputtering system were investigated in this article. The removal rate of the films increased, and the rms surface roughness decreased with the addition of an oxidizer to the tungsten slurry. Within-wafer nonuniformity was improved to below 5% when oxidizers of 5.0 and 2.5vol%, respectively, were added to the tungsten slurry. The optimized oxidizer concentration, reflected by both the rms roughness values and a hillock-free surface with the good uniformity, was 5.0vol% as shown with atomic force microscopy analysis of thin film topographies. Our CMP results will be a useful reference for advanced technology of thin films for gas sensor applications in the near future.

Improvement of the surface roughness and sensing properties of cerium dioxide thin film by chemical mechanical polishing

Cerium dioxide (CeO2) is one of the most widely used materials for oxygen gas sensors. The surface roughness of CeO2 thin films must be improved because the electrical and sensing properties of CeO2 thin films are determined by these characteristics. The authors selected chemical mechanical polishing (CMP) processing for improving the surface roughness of CeO2 thin films. The authors examined the removal rate and surface roughness of spin coated CeO2 thin films with a change of CMP process parameters such as pressure (down force) and velocity (table speed). An optimized process condition, reflected by not only the surface roughness with a hillock-free surface but also an excellent removal rate with good uniformity, was obtained. The effects of the improved surface roughness on the sensing property of CeO2 thin films were also confirmed. The authors obtained improved sensitivity of CeO2 thin films for oxygen sensors after the CMP process by the improved surface morphology. Therefore, the authors concluded that the sensing property of CeO2 thin film was strongly dependent on the surface roughness of CeO2 thin films by using a CMP process.Cerium dioxide (CeO2) is one of the most widely used materials for oxygen gas sensors. The surface roughness of CeO2 thin films must be improved because the electrical and sensing properties of CeO2 thin films are determined by these characteristics. The authors selected chemical mechanical polishing (CMP) processing for improving the surface roughness of CeO2 thin films. The authors examined the removal rate and surface roughness of spin coated CeO2 thin films with a change of CMP process parameters such as pressure (down force) and velocity (table speed). An optimized process condition, reflected by not only the surface roughness with a hillock-free surface but also an excellent removal rate with good uniformity, was obtained. The effects of the improved surface roughness on the sensing property of CeO2 thin films were also confirmed. The authors obtained improved sensitivity of CeO2 thin films for oxygen sensors after the CMP process by the improved surface morphology. Therefore, the authors concluded ...

Electrical properties of Pb(Zr,Ti)O3/CeO2/Si MFIS structure fabricated by chemical mechanical polishing (CMP) damascene process

Metal-ferroelectric-insulator-silicon field-effect-transistors (MFISFETs) of Au/PZT/CeO2/Si were fabricated by the novel method of chemical mechanical polishing (CMP) damascene process. The vertical sidewall without the surface and/or plasma damage could be easily fabricated by it. The typical ferroelectric characteristics were sucessfully obtained although the remanent polarization value was low.

Polishing damages to electrical properties of BLT thin film capacitors fabricated by damascene process of chemical mechanical polishing

BLT thin film capacitor was fabricated by the novel method of chemical mechanical polishing (CMP) process. The electrical characteristics including P-V and I-V of BLT capacitor were damaged by the polishing pressure which is one of the main factors to improve the CMP performance for BLT thin film; therefore, the lower polishing pressure must be selected for the good electrical characteristics although the removal rate was lower.

Influence of a post–chemical mechanical polishing cleaning process on the ferroelectric properties of a Pb(Zr,Ti)O3 thin film capacitor fabricated by the damascene process

The author first applied a chemical mechanical polishing (CMP) process to fabricate a ferroelectric Pb(Zr,Ti)O3 (PZT) capacitor instead of using a plasma etching process for the vertical profile without plasma damage in their previous study. The post-CMP cleaning process was very important in this CMP process. In this study, they investigated the effects of the post-CMP cleaning process on the ferroelectric properties of a PZT thin film capacitor. They proposed an optimized post-CMP cleaning process that uses a SC-1 chemical, diluted HF treatment, and an ultrasonic cleaning process. The slurry residues on the surface of the PZT thin films were removed. The polarization-voltage (P-V) characteristics showed the typical hysteresis loop of PZT thin films after a post-CMP cleaning process with the optimized conditions, while the ferroelectric characteristics could not be observed in the specimen without the post-CMP cleaning process. The remanent polarization (Pr) and coercive voltage (Vc) of the PZT thin film...

Polishing Mechanism of TEOS-CMP with High-temperature Slurry by Surface Analysis

Effects of high-temperature slurry were investigated on the chemical mechanical polishing (CMP) performance of tetra-ethyl ortho-silicate (TEOS) film with silica and ceria slurries by the surface analysis of X-ray photoelectron spectroscopy (XPS). The pH showed a slight tendency to decrease with increasing slurry temperature, which means that the hydroxyl groups increased in slurry as the slurry temperature increased and then they diffused into the TEOS film. The surface of TEOS film became hydro-carbonated by the diffused hydroxyl groups. The hydro-carbonated surface of TEOS film could be removed more easily. Consequently, the removal rate of TEOS film improved dramatically with increasing slurry temperature.

Polishing Properties by Change of Slurry Temperature in Oxide CMP

To investigate the effects of slurry temperature on the chemical mechanical polishing(CMP) performance of oxide film with silica and ceria slurries, we have studied slurry properties as a function of different slurry temperature. Also, the effects of each input parameter of slurry on the oxide CMP characteristics were investigated. The pH showed a slight tendency of decrease, the conductivity in slurries showed an increased tendency, the mean particle size in slurry decreased, and the zeta potential of slurry decreased with temperature. The removal rates significantly increased and maintained at the specific levels over 4. The better surface morphology of oxide films could be obtained at 40 of silica slurry and at 90 of ceria slurry. It is found that the CMP performance of oxide film could be significantly improved or controlled by change of slurry temperature.

Planarization Characteristics of CMP for WO 3 Film with an Addition of Oxidizers

Chemical mechanical polishing (CMP) process is one of the most useful methods for improving the surface roughness of films. The effects of CMP on the surface morphology of WO films prepared by RF sputtering system were investigated in this paper. A removal rate of films increased, and the uniformity performance of surface decreased with the addition of an oxidizer to the tungsten slurry. Non-uniformity performance of surface was superior as its value was below 5 % when oxidizers of 5.0 vol% and 2.5 vol%, respectively, were added to the tungsten slurry. The optimized oxidizer concentration, reflected both the improved roughness values and hillock-free surface with the good uniformity performance, was 5.0 vol% as an atomic force microscopy(AFM) analysis of thin film topographies. Our CMP results will be a useful reference for advanced technology of thin films for gas sensor applications in the near future.