The present disclosure concerns a method for making complementary p and n MOSFET transistors, with metal source and drain Schottky electrodes arranged on a semiconductor substrate, the source and drain electrodes of each transistor being connected by a channel controlled by a gate electrode.
The disclosure also concerns an electronic device, of the type comprising at least one p transistor and at least one n transistor, each of the transistors including a metal source and drain Schottky electrode, formed from a silicide arranged on a semiconductor substrate, the source and drain electrodes of each transistor being connected by a channel controlled by a gate electrode.
The disclosure also concerns a processor including such an electronic device, as illustrated in FIG. 15.
U.S. Pat. No. 7,052,945 B2 describes a method for making complementary p and n MOSFET transistors, with metal source and drain Schottky electrodes arranged on a semiconductor substrate. The production of the source and drain electrodes for each p transistor is done from a platinum silicide, palladium silicide or iridium silicide. The production of the source and drain electrodes for each n transistor is done from a rare earth-based silicide, such as erbium. The source and drain electrodes of each transistor are connected by a channel. The channel of each p transistor is doped with an element from the group consisting of: arsenic, phosphorous and antimony. The channel of each n transistor is doped with an element from the group consisting of: boron, indium and gallium. This method makes it possible to obtain, for each p and n transistor, a channel with a length smaller than 100 nanometers, the length of the channel being the distance separating the source and drain electrodes, connected by said channel.
According to the ITRS (International Technology Roadmap for Semiconductors) 2005 roadmap published by the Semiconductor Industries Association in 2005, the bottlenecks for the technological node corresponding to a gate length of 18 nm are in particular the following:                I: high solubility of the dopant and very low depth of the extensions of the source and drain electrodes at their junction with the channel (xj=5.1 nm),        II: an abrupt concentration gradient at the junctions between the channel and the source and drain electrodes (less than 1 nm/decade),        III: a very small silicide thickness (10 nm),        IV: a reduced silicon consumption during the silicide formation (less than 8.4 nm),        V: a very low resistance per silicide square (15.8 Ω/□ for a silicide thickness of 10 nm),        VI: a very low specific contact resistance of the source electrode and drain electrode at the interface between the silicide and the channel (less than 5.4×10−9 Ω×cm2), and        VII: a low total contact resistance (from 60 to 80 Ω×μm).        
The complementary p and n MOSFET transistors described in U.S. Pat. No. 7,052,945 B2 make it possible to guard against bottlenecks I and II, the junctions between the source and drain Schottky electrons and the channel not being doped, and to guard against bottlenecks III to V, the thickness of silicide not being limited for the source and drain Schottky electrodes.
However, the complementary p and n MOSFET transistors described in U.S. Pat. No. 7,052,945 B2 have Schottky barrier heights in the vicinity of 0.2 eV. For the source and drain electrodes of the p transistor, produced from a platinum silicide, the Schottky barrier height is substantially equal to 0.15 eV. For the source and drain electrodes of the n transistor, produced from a rare earth-based silicide such as ytterbium, erbium, respectively, the Schottky barrier height is substantially equal to 0.2 eV, 0.25 eV, respectively. These relatively high Schottky barrier heights do not make it possible to resolve technological bottlenecks VI and VII described above. They also do not make it possible to obtain performance comparable to the performance obtained with MOSFET transistors made using a traditional approach, i.e. MOSFET transistors with strongly doped junctions between the channel and the source and drain electrodes. Indeed, a high barrier height prevents one from obtaining a satisfactory specific contact resistance for the source and drain electrodes.
Moreover, the method for making complementary p and n MOSFET transistors, described in U.S. Pat. No. 7,052,945 B2 is relatively complex, since it involves integrating rare earth-based silicide to made source and drain electrodes of n transistors. The integration of rare earths is very sensitive to oxygen and must be done in an ultrahigh vacuum, this term being used to designate very high vacuums.