Active solid-state devices (e.g. – transistors – solid-state diode – Non-single crystal – or recrystallized – semiconductor... – Field effect device in non-single crystal – or...
Reexamination Certificate
2002-12-12
2003-09-30
Nelms, David (Department: 2818)
Active solid-state devices (e.g., transistors, solid-state diode
Non-single crystal, or recrystallized, semiconductor...
Field effect device in non-single crystal, or...
C257S051000, C257S052000, C257S064000, C257S065000, C257S066000, C257S067000, C257S068000, C257S069000, C257S347000
Reexamination Certificate
active
06627919
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a nickel germanosilicide on SiGe integrated circuit device, and a method of making the same and, more particularly, to a thermally stable nickel germanosilicide on SiGe integrated circuit device, and a method of making the same, wherein during fabrication iridium or cobalt is added at the Ni/SiGe interface to decrease the sheet resistance of the device.
BACKGROUND OF THE INVENTION
The development of Si-Ge based integrated circuit devices has created the need for stable, low thermal budget, low resistivity metal-silicide contacts to SiGe alloys. Metal/SiGe systems based on titanium, cobalt, zirconium, nickel, palladium and platinum have been studied. However, these systems show poor phase segregation. In particular, during the thermal anneal, in the Ti/SiGe system, excess germanium combines with silicon and nucleates as SiGe precipitates along the grain boundaries. In the Co/SiGe system, excess Ge diffuses to the grain boundary to form Ge-enriched clusters. Due to this multi-phase formation, application of these materials to devices with small feature sizes is difficult unless a silicon buffer layer is used.
Recently, nickel has been applied to poly-silicon germanium (poly-SiGe) to form nickel germanosilicide poly-silicon germanium (Ni(Si
x
Ge
1−x
)/poly-Si
0.8
Ge
0.2
) gate structures without a polysilicon buffer layer. Use of this structure has been demonstrated to result in a ten percent increase of the saturated drain current (Idsat) in 0.15 &mgr;m pMOSFET. However, the thermal stability of this nickel germanosilicide is very poor. A sharp increase in the sheet resistance is observed at about 600° C. Accordingly, there is a need to improve the thermal stability of nickel germanosilicides.
SUMMARY OF THE INVENTION
The system of the present invention provides a thermally stable nickel germanosilicide on SiGe integrated circuit device, and a method of making the same, wherein during fabrication iridium or cobalt is added at the Ni/SiGe interface to decrease the sheet resistance of the device. The device comprising nickel silicide with iridium on SiGe shows thermal stability at temperatures up to 800° C. The device comprising nickel silicide with cobalt on SiGe shows a decrease in the sheet resistance with temperature, i.e., the resistance remains low when annealing temperatures extend up to and beyond 800° C.
Accordingly, an object of the invention is to provide a thermally stable nickel germanosilicide on SiGe integrated circuit device, and a method of making the same.
Another object of the invention is to provide a thermally stable nickel germanosilicide on SiGe integrated circuit device, and a method of making the same, wherein during fabrication iridium or cobalt is added at the Ni/SiGe interface.
Still another object of the invention is to provide a thermally stable nickel germanosilicide on SiGe integrated circuit device that has a low sheet resistance at temperatures up to 800° C. or more.
REFERENCES:
patent: 6242779 (2001-06-01), Maekawa
Hsu Sheng Teng
Maa Jer-shen
Tweet Douglas James
Krieger Scott C.
Rabdau Matthew D.
Ripma David C.
Sharp Laboratories of America Inc.
Tran Mai-Huong
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