Application of Arsenic Plasma Doping in Three-Dimensional MOS Transistors and the Doping Profile Evaluation

Abstract

The application of plasma doping in three-dimensional (3-D) metal oxide semiconductor (MOS) transistors is proposed. One of the key steps in for fabricating 3-D MOS transistors with high-aspect-ratio channels is 3-D doping. Thus, plasma doping is analyzed and its profile is evaluated. Since conventional evaluation methods are not very effective for impurity concentration profiling along the sidewall of a vertical structure, a new method utilizing impurity-enhanced oxidation is proposed. By this method, an arsenic-doped layer of approximately 1 Â 10 20 cm À3 in concentration has been formed uniformly for a beam of 1 mm height and 0:2 À 1 mm width.

Formation, nature, and stability of the arsenic-silicon-oxygen alloy for plasma doping of non-planar silicon structures

“…Post ion implant anneal studies in which annealing has been performed in oxygen environments show that activation and profile results strongly depend on oxygen exposure. 16,17 Work by Kobayashi et al 9 and a more recent paper by Steen et al…”

“…Saturation is coincident with segregation. [9][10][11] Plasma doping is performed near room temperature; annealing activates infused dopants and evaporates excess protective material. Details of the plasma doping process are summarized by Ueda et al…”

Ultrashallow Arsenic n+/p Junction Formed by AsH3 Plasma Doping

“…Plasma doping (PLAD) was proposed as an alternative to ion implantation to form an ultrashallow junction in a twodimensional (2-D) or three-dimensional (3-D) transistor structure. [1][2][3][4] Conventional ion implantation can not be applied to the doping of 3-D transistor structures due to the non-uniformity of the area to be doped, such as the edge pattern and the complex shape of the total area. However, unlike conventional ion implantation methods, the PLAD technique can achieve a uniformly doped area.…”

“…For these reasons, PLAD is a useful process technology for 2-D and 3-D complementary metal-oxidesemiconductor (CMOS) technology. [4][5][6] Generally speaking, there are two kinds of PLAD sources: dopant source gas, such as B 2 H 6 , PH 3 , and AsH 3; and balance gas, which is used to dilute dopant source gas, such as hydrogen or helium. However, these sources incorporate ions that cause various problems in junction characteristics.…”