A novel atomic doping technology for ultra-shallow junction of SOI-MOSFETs

Vapor Phase Doping with N-type Dopant into Silicon by Atmospheric Pressure Chemical Vapor Deposition

“…Subsequently, the wafer was cooled down to the dopant gas exposure temperature in H 2 ambient. The VPD was performed at 400~600 o C at atmospheric pressure by using PH 3 and AsH 3 0.1% diluted in H 2 . The PH 3 or AsH 3 flow was 50 ~ 200 standard cubic centimeters per minutes (sccm) during 0.1~100 minutes.…”

“…Subsequently, they are diffused into the substrate by a drive-in anneal [3] or by epitaxial incorporation under one or more successive monolayers (MLs) of epitaxial Si for the dopant activation. Because the deposition follows the device topography [1,2], these ALD techniques are expected to lead in a natural way to fully conformal junctions, precisely controlled doping process and sharp doping profile without any damages.…”

“…In these ALD approaches, the dopant atoms are deposited on the Si surface through the thermal decomposition of gaseous precursors such as diborane (B 2 H 6 ), phosphine (PH 3 ) and arsine (AsH 3 ) in a standard chemical vapor deposition (CVD) reactor or gas source molecular beam epitaxy system. Subsequently, they are diffused into the substrate by a drive-in anneal [3] or by epitaxial incorporation under one or more successive monolayers (MLs) of epitaxial Si for the dopant activation. Because the deposition follows the device topography [1,2], these ALD techniques are expected to lead in a natural way to fully conformal junctions, precisely controlled doping process and sharp doping profile without any damages.…”

A simple two-step phosphorus doping process for shallow junctions by applying a controlled adsorption and a diffusion in an oxidising ambient

“…Similar methods were described in [9,10] for the doping of silicon with boron and arsenic, respectively. However, a cover layer of silicon oxide was necessary in order to prevent the desorption and the outdiffusion of the dopants.…”

“…The deposition of an additional capping layer is a method to prevent such a desorption. New doping processes sometimes referred to as atomic-layer doping (ALD) were presented for boron doping [9] and arsenic doping [10], applying an oxide capping layer in order to avoid dopant loss from the surface. In this report a similar low pressure doping process is presented, which is composed of the adsorption of phosphorus on the silicon surface and a rapid thermal diffusion in an oxidising ambient without the deposition of an oxide capping layer.…”