Formation of PtSi-contacted p+n shallow junctions by BF+2 implantation and low-temperature furnace annealing

Abstract

This work investigates the characteristics of PtSi-silicided p+n shallow junctions fabricated by implanting BF+2 ions into either the Pt/Si (ITM scheme) or the PtSi/Si (ITS scheme) structure followed by annealing in N2 furnace at temperatures from 650 to 800 °C. For a structure with Pt film of 30 nm thickness or PtSi film of 60 nm thickness, the implantation energy ranges from 40 to 80 keV with a dose ranging from 1×1015 to 1×1016 cm−2. For the ITS samples with BF+2 implantation at 40 keV, all ions are confined in the PtSi layer; therefore, only a modified Schottky junction is formed by the diffusion of boron atoms from the PtSi film during the annealing. The junction depth may be as shallow as 30 nm from the PtSi/Si interface. A complete p+n junction is formed for the ITM samples with implantation at 40 keV as well as all the samples implanted at 80 keV. The junction thus obtained has a forward ideality factor lower than 1.02 and a reverse current density less than 0.2 nA/cm2 at −5 V. Activation energy measurement indicates that most of the implantation damages have been recovered after annealing at a temperature as low as 700 °C. The reverse area and peripheral leakage current density are separated by measuring diodes of different perimeter/area ratio. For good samples, the reverse peripheral current comes from the surface generation current within the depletion region underneath the field oxide. All of the experimental results reveal that either Pt or PtSi film can be employed as an efficient barrier film in the ITM/ITS technique to form excellent and ultrashallow junctions with a low thermal budget.

High-Speed Programming Not-OR Flash Memory Cells With Titanium Disilicide Drain

“…Among the metal silicides utilized in SB NOR flash memories, titanium disilicide (TiSi 2 ) and cobalt disilicide layers have been the most extensively used silicide materials in the industry because of their good thermal stability and low electrical resistivity. [8][9][10][11] Unique structures of NOR flash memories with high reading and programming speeds have been extensively designed. Although some studies of the decrease in leakage current in asymmetric Schottky MOSFETs with a SB source junction and a p-n drain junction have been performed, 12) studies of NOR flash memory cells with high speed programming and high driving current density utilizing an asymmetric SB formed using a TiSi 2 drain have not yet been carried out.…”

Formation of NiSi-Silicided p+n Shallow Junctions by BF2 + Implantation into/through Silicide and Rapid Thermal Annealing

“…Low-temperature processing, shallow-junction formation, and low contact resistance are the major advantages of the SADS process. [1][2][3][4][5][6][7] Among the metal silicides, titanium disilicide (TiSi 2 ) and cobalt disilicide (CoSi 2 ) have been widely used in salicide processes throughout the industry because of their good thermal stability and low electrical resistivity. However, some critical drawbacks limit their applications to future CMOS technology.…”

Effect of fluorine incorporation on the thermal stability of PtSi/Si structure

“…peratures lower than 750°C [3], [4]. All of these indicate that PtSi should be a choice for application to very large scale bipolar and MOS integrated circuits.…”