Han-Byul Kang

Morphology, Thermal Stability, And Solderability Of Electroless Nickel–Phosphorus Plating Layer

We studied the growth kinetics and characteristics of electroless nickel–phosphorus (EN–P) deposition layer on Cu substrate in an acid plating bath with sodium hypophosphite as the reducing agent. The individual nodules of the EN–P layer increased in size but decreased in number with increasing plating time and pH, i.e. the root-mean-square (RMS) roughness of the EN deposit decreased. In addition, the plating rate of the EN layer increased with increasing plating bath pH. X-ray diffraction (XRD) analyses revealed that the as-plated deposit was in an amorphous phase, while the heat-treated layer was composed of crystallized Ni and Ni3P compound. The solderability of the EN layer increased with decreasing P content. In addition, the wetting force increased with increasing surface roughness. The present study clearly showed that the solderability behavior of the EN layer is affected by both surface composition (P content) and morphology.

Characteristics of high-k gate dielectric formed by the oxidation of sputtered Hf'Zr'Hf thin films on the Si substrate

We have investigated the effects of high temperature annealing on the physical and electrical properties of multilayered high-k gate oxide [HfSixOy/HfO2/intermixed-layer(IL)/ZrO2/intermixed-layer(IL)/HfO2] in metal-oxide-semiconductor device. The multilayered high-k films were formed after oxidizing the Hf/Zr/Hf films deposited directly on the Si substrate. The subsequent N2 annealing at high temperature (⩾ 700 °C) not only results in the polycrystallization of the multilayered high-k films, but also causes the diffusion of Zr. The latter transforms the HfSixOy/HfO2/IL/ZrO2/IL/HfO2 film into the Zr-doped HfO2 film, and improves electrical properties in general. However, the thin SiOx interfacial layer starts to form if annealing temperature increases over 700 °C, deteriorating the equivalent oxide thickness.

Microstructural evolution of nickel-germanide in the Ni1−xTax/Ge systems during in situ annealing

The formation and morphological evolution of the germanides formed in the Ni1−xTax/Ge (x=0 and 0.1) systems were examined using ex situ and in situ annealing experiments. It was observed that the Ni-germanide in the Ni0.9Ta0.1/Ge system remained stable at temperatures up to 550 °C whereas the Ni-germanide in the Ni/Ge system agglomerated and was unstable. Microstructural and chemical analyses of the Ni0.9Ta0.1/Ge system during and after in situ annealing in a transmission electron microscope confirmed that the Ta-rich layer was formed by the accumulation of Ta atoms on the interface between the Ni0.9Ta0.1 alloy film and the Ge substrate during the diffusion reaction, and a small amount of residual Ta was found in the Ni-germanide grains. Ultimately, the Ta-rich layer helps reduce the level of agglomeration in the Ni-germanide film and improves the thermal stability of Ni-germanide.

A study of organic contamination control on photomask surface for 65nm tech node

In recent years, organic compounds have been clarified as one of major root causes of the haze, and carbon and amine components are major of them to organize. Therefore, both two should be controlled simultaneously for preventing haze defects on photomask. It is well known that UV/O3 treatment has a strong efficiency of removing organic matters1. For that reason, we have inserted it into our cleaning process, especially for EA.PSMS. And the surface variation of mask, after UV/O3 treatment, has been confirmed by the change of surface free energy on it. And organic matters remaining on mask surface have been identified by Gas Chromatography Mass Spectrometry (GC MS) with two different sample preparation methods: Thermal Desorption (TD) and direct extraction. As a result of UV/O3 treatment, we confirmed that it has an excellent removing efficiency of aromatic compounds and semi-volatile organics on mask surface. Finally, through the haze accelerating tests, we have known that conventional SPM/SC-1 cleaning with UV/ O3 treatment has been having a much higher threshold energy value in terms of causing haze defects on masks about 20 times higher than that of the cleaning with just SPM/SC-1.

TEM study on the interfacial reaction between electroless plated Ni−P/Au UBM and Sn−3.5Ag solder

This study examined the interfacial reaction between electroless plated Ni−P/Au under bump metallization (UBM) and a eutectic Sn−3.5Ag solder using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The chemical and crystallographic analysis using TEM provided important information on the microstructural evolution at the interface. In this study, UBM was prepared by the electroless plating of Au (0.15 μm)/Ni-15 at %P (5 μm) on a bare Cu substrate and was then reacted with a Sn−3.5Ag eutectic solder at 260°C for various amounts of time to examine the different sequential stages of the interfacial reaction TEM analyses confirmed that beside the Ni3Sn4 layer, there were three more IMC layers at the interface: the Ni−Sn−P ternary layer, Ni3P layer, and the layer of phase mixture of the Ni3P and Ni2SnP ternary phases.

Control of chemical residue on photomasks using thermal treatment

We choose thermal treatment as part of a methodology to remove chemical residue on the surface of a mask. This new step of thermal treatment is inserted into our standard cleaning process for embedded attenuate phase shift masks (EAPSMs). The treatment is carried out in a modified hot plate system at various temperatures and times. After thermal treatment, ion chromatography measures the residual ions on a given surface. The thermal treatment is found to considerably reduce residual sulfate ions on the mask surface. The remaining sulfate ions on the mask are <0.18 ng/cm2 using thermal treatment.