Gyu Hyun Kim

Effect of Drying Liquid on Stiction of High Aspect Ratio Structures

In this paper, we studied stiction behavior of HAR pattern (line and space pattern) dependence on adhesion force with surface tension of drying liquid and surface contact angle. Surface tension effect was evaluated with various drying liquids such as IPA, ethanol and HFE (hydrofluoroether) chemical. Patterns treated by dHF, APM and surface modifier were introduced to investigate dependence of pattern collapse on contact angle. The high temperature D.I. water rinse followed by high temperatures drying using liquid with low surface tension was a most effective. Furthermore, surface modification method using HMDS (hexamethyldisilazane) chemical was also effective.

Effect of nitrogen doping on the performance of Ge2Sb2Te5 films in chemical mechanical polishing

The effects of nitrogen doping on Ge2Sb2Te5 (GST) films for chemical mechanical polishing (CMP) and their performance were investigated. Nitrogen doping was controlled using a rapid thermal annealing system with nitrogen gas flow rates that varied from 0 to 20 sccm at 300 °C. The material removal rate, surface characteristics and crystal structure of the nitrogen doped GST films after CMP were examined by X-ray diffraction (XRD), scanning electron microscopy, and atomic force microscopy. XRD patterns revealed that the intensities of crystalline diffraction peaks decreased with increasing nitrogen flow rate. With increasing flow rate, the material removal rate and surface roughness of GST films reduced owing to nitrogen doping effects. Current–voltage (I–V) characteristics of the nitrogen doped GST films after CMP showed changes in the threshold voltage owing to changes in crystallization and surface roughness. Further, Nitrogen doped GST films in CMP showed a strong correlation with material removal rate, surface roughness, and crystallization.

Evaluation of wafer drying methods for GIGA-LEVEL device fabrication

This study deals with drying induced water marks dependency on the last cleaning methods, substrate conditions, and drying pre-step delaying times, which are supposed to become a big issue with down scaling of device geometry. The data show that water marks induced by drying failure increase with increasing contact angle on the various surfaces. They are mainly composed of either silicon oxide only or silicon oxide with organic compounds. The former is removed by a dilute HF and/or hot SC-1 treatment and the latter is removed by organic removal cleaning followed by dilute HF etching.

Effect of Wet Treatment on Stability of Spin-On Dielectrics for STI Gap-Filling in Nanoscale Memory

As a design rule of memory devices is scaled down to sub-100 nm, shallow trench isolation (STI) technology is faced with gap-filling problem in case of CVD oxide and O3-TEOS oxide processes. To overcome the gap-filling problem, a perhydropolysilazane (PHPS) based spin-on dielectric (SOD) has been implemented for nanoscale devices because of self-planarization and excellent gap-filling property [1]. However, the stability of the SOD has been concerned about because it has relatively softer and more porous than conventional HDP oxide. In this paper, we report the effect of wet oxidant treatment on the stability of the SOD for STI gap-filling.

Elimination of Watermark on Extremely High-Doped Poly-Silicon Surfaces Using HF-Vapor Cleaning

Introduction Advanced mobile and high performance device manufacturing requires the development of low power, high density and high speed DRAM devices that operate at low voltages. However, as threshold voltage (Vt) decreases, the potential for Short Channel Effect (SCE) increases within the buried channel (BC) pMOSFET. This issue has led to development of the dual-gate surface channel (SC) pMOSFET to increase the SCE margin. During the Dual Poly Gate (DPG) process, highly doped P+ polysilicon and N+ polysilicon surfaces are exposed in the clean process, which may cause watermark problems. To overcome the water-mark generation problem during wafer drying due to differences of wetting characteristics and contact angles between N+ polysilicon and P+ polysilicon surfaces following the clean prior to WSix deposition, we altered the conventional wet clean to an SC-1 last clean and dry followed by a single-wafer HF vapor clean.