Chang Jin Kang

Enhancement of Mask Selectivity in SiO2 Etching with a Phase-Controlled Pulsed Inductively Coupled Plasma.

We developed a new method to enhace the photoresist selectivity in SiO2 etching by modulating both the source and bias powers and by controlling the phase difference between the modulation functions. Enhancement of mask selectivity was observed in the pulse plasma, especially in the out-phase condition. To understand the heavy polymerization in the out-phase pulse plasma, we analyzed the ion energy distributions of CFx+(x=1, 2, 3) ions using the energy-spectroscopic quadrupole mass spectrometer (QMS) and measured the waveforms of the bias power with a high-voltage probe which was connected directly to the wafer. Two distinct plasma potential distributions were obtained in the pulse plasma and the dc bias voltage (VDC) was maximum in the out-phase condition. The heavy polymerization in the out-phase condition was explained as a result of high VDC. We also investigated the emission intensity of the C2 (516.5 nm) line, and found that C2 species were precursors of the polymerization and contributed to the heavy polymerization in the out-phase condition.

Selective Epitaxial Growth of Silicon for Vertical Diode Application

Selectivity control in silicon selective epitaxial growth (SEG) for deep contact patterns, which is one of the key processes for silicon-based stacked devices and cell switches for next generation memories, was studied. Absolute values of selectivity loss during silicon SEG using the most popular H2/dichlorosilane (DCS)/HCl gas system were evaluated using a commercialized inspection tool in 200 mm wafers with real contact patterns. It was revealed that HCl/(DCS+HCl) ratio and the contact structure played a crucial role in suppressing selectivity loss. The number of selectivity losses in an entire wafer was less than 100 when the HCl/(DCS+HCl) ratio was larger than 0.41. The vertical pn diode prepared using the silicon SEG process with elaborate selectivity control showed more remarkable electrical abilities to accommodate current flow than polycrystalline silicon (poly-Si), including the ideality factor and swing, and reverse leakage current.

Leakage current reduction mechanism of oxide-nitride-oxide inter-poly dielectrics through the post plasma oxidation treatment

High quality oxide–nitride–oxide (ONO) inter-poly dielectrics were successfully fabricated by the optimized plasma oxidation without H2. The bottom low pressure chemical vapor deposition (LPCVD) oxides treated by the conventional N2O annealing step were subjected to the post deposition process using a plasma treatment. This process reduces both the leakage current and the stress-induced leakage current (SILC), while no thickness increase of the bottom LPCVD oxides was observed due to the plasma treatment. Based on the photo electron injection technique, it is found that the O2 plasma oxidation method significantly reduces the defect centers located at 1.67 nm away from the bottom oxide/floating gate interface.

Systematic method to optimize conditioning process through real time plasma monitoring

A systematic method to optimize conditioning processes is introduced. By using the plasma monitoring tools such as self-excited electron resonance spectroscopy (SEERS) and optical emission spectroscopy (OES), chamber conditions are analyzed in real time and a conditioning process appropriate to each chamber condition is determined quickly. Through this real time analysis and rapid action, total time to optimize the conditioning process is significantly reduced