Papers by Keyword: CMP

Abstract: Laser scattering characteristics of typical CMP-induced defects such as particles and microscratches with the size of sub-micron order are investigated using a developed automated scattered light measurement system. The measurement system has an ability to detect three-dimensional distribution of scattered light from the defects with high sensitivity. The angular distributions of scattered light from the standard PSL (Polystyrene latex) spheres and microscratches reveal that scattering characteristics of microscratches are quite different from those of Particles. The scattered light from the PSL sphere is detected mainly ahead. In contrast, the scattered light from the microscratches only exists in the direction perpendicular to its length dimension at an oblique incidence maintaining the sheet-shaped pattern, even if its orientation relative to the incident direction is changed. Optical arrangement for defect detection and classification is suggested based on the experimental results.

Abstract: The miniaturization of semiconductor devices is advancing rapidly. The requirement for wafer flatness is becoming increasingly stringent as the use of shorter wavelengths in the latest laser lithography results in a smaller focusing depth of field. In our research, a flatness of 0.1 µm has been achieved over an entire 12" wafer surface by planarization with oscillation speed control type polishing. However, in addition it is necessary to increase the removal rate in order to reduce the polishing time. Although high rotational speed polishing is a solution to meet this requirement, the polishing characteristics change with the rotational conditions. Using a simulation program, we calculated that the stock removal saturates as the rotational speeds of the wafer and polishing pad are increased beyond a certain point. Also, experimental results showed that at high rotational speeds actual stock removal is significantly less than that indicated by the simulation, and that too much slurry causes unnecessary etching.

Abstract: The slurry of Copper chemical mechanical planarization for ultra large-scale integrate circuit (ULSI) usually contains oxidizer, etchant, complexing reagent and corrosive inhibitor. In planarization process, the corrosive inhibitor has an important effect on the planarization. Only if the concave surface of the wafer is properly protected from corrosion by the inhibitor, the process can obtain perfect surface planarity. In this paper, with Fe(NO3)3 as an oxidant and several corrosive inhibitors selected, the corrosive efficiency of slurries are investigated. The static etching rate and the polishing material removal rate of wafer are obtained. The electrochemical behavior of the slurry is investigated by the potentiodynamic polarization studies. And the inhibitive efficiency of the related corrosive inhibitors is calculated from the polarization data. X-ray diffraction is applied to analyze the composition modification of the copper surface. Atom force microscopy is applied to measure the surface topography of corrosive copper wafer and the value of surface roughness is measured by ZYGO surface analysis system. The result shows that the benzotriazole (BTA) is a perfect corrosive inhibitor. With addition of 0.1wt% BTA into 1.5wt% Fe(NO3)3 solution, the inhibitive efficiency can reach 99.1%. The polishing test shows that if only 1.5wt% Fe(NO3)3 is added as an oxidizer without any other additive, the surface roughness of the polished wafer is 26.9Å, while with 0.1wt%BTA added in the meantime, 5.2 Å of surface roughness can be obtained.

Abstract: The GaAs wafer is widely applied to semiconductor element related to telecommunication and semiconductor laser. In this research, novel fine polishing technology of GaAs wafer was investigated using TiO2-H2O2-H2O slurry system instead of NaOCl which is conventionally used as polishing slurry. And then the ultraviolet ray was applied in order to investigate the effect of TiO2 photocatalyst. The polishing characteristics were estimated by optical microscope and WYKO optical profiler. It was found that the slurry system was available for GaAs wafer polishing although the polishing rate was lower than NaOCl. Moreover, the effect of the photocatalyst of TiO2 including in slurry was investigated. In this polishing system, the effect of the photocatalyst on GaAs wafer CMP mechanism has not been confirmed yet.

Abstract: A microtibological study of the effect of the CMP machining surface damages (SD) on the micromechanical properties of AlN electro-static chuck (ESC) for silicon plasma etching is presented. AFM and SEM examinations of the AlN ESC, which were CMP finished to a surface roughness, Ra = 20 nm, have revealed machining geometry errors and chemical mechanical SD caused by the CMP slurry. The elastic modulus (E) and hardness (H) of AlN and those of yttrium (Y) particles were discretely clarified using localized nanoindentation technique. The results showed that the CMP machining SD fatally affected the AlN/Y boundary strength and resulted to errors in the first contact points between the indenter and the sample. In addition to SD, the micro scale viscoelasticity phenomena of AlN in indentation caused peculiarities at peak loads in the load vs. depth plots. Under these circumstances, the values of E and H measured using Oliver and Pharr's method are in fact underestimated; E = 400 GPa and H = 20 GPa for AlN particles, 300 GPa and 17 GPa for Y particles and 500 GPa and 16 GPa for AlN/Y interface, respectively.

Abstract: Nano-crystalline CeO2 was synthesized by the mechanical milling and subsequent heat-treatment from the mixture of Ce(OH)4 as precursor, and NaCl as diluent. The diluent provided diffusion barrier during milling and heat-treatment, which was easily dissolved out by deionized water. The size of crystallite and the strain variance of CeO2 were depended on the temperature and heat-treatment time: increased with the temperature (400~700oC) and time (1~24 hours) increasing, and saturated near at 20nm in size owing to the densification of diluent. The synthesized nano-crystalline CeO2 powder was applied as an abrasive in CMP (Chemical Mechanical Planarization) slurry. When blanket-type SiO2 and Si3N4 wafers were polished with the slurries, the removal rates (RR) of SiO2 and Si3N4 wafers and selectivities (RRSiO2/RRSi3N4) were influenced by synthetic condition of abrasive, the suspension stability and the pHs of slurries.