Hun-jung Yi

Spatially resolvable optical emission spectrometer for analyzing density uniformity of semiconductor process plasma

We proposed a spatially resolved optical emission spectrometer (SROES) for analyzing the uniformity of plasma density for semiconductor processes. To enhance the spatial resolution of the SROES, we constructed a SROES system using a series of lenses, apertures, and pinholes. We calculated the spatial resolution of the SROES for the variation of pinhole size, and our calculated results were in good agreement with the measured spatial variation of the constructed SROES. The performance of the SROES was also verified by detecting the correlation between the distribution of a fluorine radical in inductively coupled plasma etch process and the etch rate of a SiO(2) film on a silicon wafer.

Nonoxidative Aqueous Cleaning Solutions for Tungsten Layers

Aqueous cleaning solutions were developed for postetch cleaning of tungsten layers to replace the amine-based organic strippers. They are composed of tetramethylammonium hydroxide, HF, and two additives. Even the cleaning recipes without a strong oxidant, such as hydrogen peroxide, could remove postetch residues formed by reactive ion etching and they also had the same particle removal efficiency compared to ammonium and hydrogen peroxide mixture known as RCA Standard Clean. The concentration of metal ion on the wafer surface after cleaning by them was under 1010 atoms/cm 2 . The effects of the cleaning could be explained by applying Pans double-layer model [J. Electrochem. Soc., 148, G315 (2001)]. In fact, these cleaning solutions made it possible to decrease the resistances of tungsten bit lines and metal contacts and contributed to yield enhancement.