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Replacement of Forming Gas Anneal by an Applied Voltage

IP.com Disclosure Number: IPCOM000013328D
Original Publication Date: 2001-Apr-14
Included in the Prior Art Database: 2003-Jun-18
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Abstract

The further scaling of MOSFETs is endangered by the early breakdown of smaller devices, when the gate oxide reaches a thickness of 1-2 nm. In the production process, gate oxides are exposed to a forming gas anneal (H 2 ,N 2 ), which saturates any dangling bonds near the interface. The hydrogen introduced however is responsible for the dielectric breakdown. Thus it would be desirable to saturate dangling bonds and limit the extent of the oxygen defi- cient suboxide near the Si/SiO 2 interface without introducing hydrogen. It is proposed to remove the dangling bonds by applying a voltage to the oxide after oxygen in a hydrogen- and oxygen-free ambient. The polarity of the voltage needs to be such that the substrate is positive Si/SiO 2 and the surface is at the near the anode.

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Replacement of Forming Gas Anneal by an Applied Voltage

  The further scaling of MOSFETs is endangered by the early
breakdown of smaller devices, when the gate oxide reaches a
thickness of 1-2 nm. In the production process, gate oxides are
exposed to a forming gas anneal (H2 ,N2 ), which saturates any
dangling bonds near the interface. The hydrogen introduced however
is responsible for the dielectric breakdown. Thus it would be
desirable to saturate dangling bonds and limit the extent of the
oxygen defi- cient suboxide near the Si/SiO2 interface without
introducing hydrogen. It is proposed to remove the dangling bonds
by applying a voltage to the oxide after oxygen in a hydrogen- and
oxygen-free ambient. The polarity of the voltage needs to be such
that the substrate is positive Si/SiO2 and the surface is at the
near the anode.

Dangling bonds can be attributed to the oxygen deficiency
expressed as suboxide and to open bonds near the interface. Every
dangling bond is considered as a defect. These defects are
charged and their diffusive motion can be controlled by a
magnetic field. In particular the defects are such that positive
defects correspond to silicon excess defects and negative defects
are oxygen excess defects. By applying a voltage across the
structure silicon rich defects can be guided to the interface
where they accumulate and form silicon, thus shifting the phase
boundary. Thus the oxide will become thinner, but less
oxygen-deficient. Thus the same effect is obtained as with...