Junkou Takagi

PREPARATION OF SELF-ASSEMBLED MERCAPTOALKANOIC ACID MULTILAYERS ON GAAS (110) SURFACES

Mono- and double layer films have been formed by the self-assembly of 16-mercapto-hexadecanoic acid, (MHDA), HS(CH2)15COOH, via selective ionic interaction. To understand the formation process in the nanometer length scale, atomic force microscopy (AFM) studies have been conducted in combination with micro X-ray photoelectron spectroscopy (µ-XPS), Auger electron spectroscopy (AES) and micro-fourier transform infrared spectroscopy with the attenuated total reflection method (µ-FTIR ATR). After the formation of a self-assembled monolayer (SAM) was completed, the surface treated with copper ions was immersed in a solution of MHDA. By this method, an atomically smooth double layer was successfully formed on cleaved GaAs (110) surfaces. The formation speed of the second layer was faster than that of the SAM, indicating stronger interaction of thiol functional groups with Cu2+ ions than with GaAs surfaces.

Novel Oxygen Free Titanium Silicidation (OFS) Processing for Low Resistance and Thermally Stable SALICIDE (Self-Aligned Silicide) in Deep Submicron Dual Gate CMOS (Complementary Metal-Oxide Semiconductors)

A low resistance and thermally stable TiSi 2 self aligned silicide (SALICIDE) for deep submicron p + and n + dual gate complementary metal-oxide semiconductors (CMOS) has been developed. This was achieved through the use of a novel oxygen free silicidation (OFS) process using a reaction between a titanium included nitrogen (Ti x N y ) and an oxygen free poly-Si-gate. The oxygen free poly-Si was realized using low pressure chemical vapor deposition (LPCVD) system with nitrogen flow Load-Lock chamber. The OFS TiSi 2 film did not agglomerate after the treatment of the RTA at 1050°C for 20 s in a N 2 atmosphere and the additional furnace annealing at 900°C for 30 min. in a N 2 atmosphere. For both n + and p + gates, low sheet resistances (about 2.8 Ω/square.) were achieved under the 0.2 μm size

Elevated Polycide Source/Drain Shallow Junctions with Advanced Silicidation Processing and Al Plug/Collimated PVD (Physical Vapor Deposition)-Ti/TiN/Ti/Polycide Contact for Deep-Submicron Complementary Metal-Oxide Semiconductors

Low-resistivity shallow junctions and completely filled contact technologies have been developed. These were realized by forming the elevated polycide source/drain junction structure and Al plug/collimated PVD-Ti/TiN/Ti/Ti-polycide (APPOCIDE) contact structure through the use of advanced silicidation processes called AAS and BAS (arsenic ions doped into the polycide layer after silicidation and boron ions doped into the polycide layer after silicidation). About 2.0–2.1 Ω /square sheet resistances of n+-Ti-polycide and p+-Ti-polycide were reached at the same level as that of undoped Ti-polycide. Contact resistivities were 2–3×10-9 Ω cm2 for a 0.35-µm-diameter contact on both n+ and p+. These contact resistivities were two orders of magnitude lower than that of the conventional Al/TiN/Ti/n+ or p+-silicon structure. Furthermore, we proposed a unique consideration for the reasons for the relative difficulty in achieving silicidation with low sheet resistance of TiSi2 layer on n+- polysilicon as compared to that on undoped- polysilicon.