Schottky barriers, silicides

Platinum-rhodium thermocouple, 24 461 Platinum silicide Schottky barrier arrays, 19 157-158... 

Scholl reaction, 12 171 Schotten-Baumann procedure, 10 485 Schotten-Baumann reaction, 19 798 Schottky barrier, 19 137, 138 Schottky barrier arrays, platinum silicide, 19 157-158... 

Finally, surface analysis has been used in the investigation of metal silicides used to form rectifying Schottky barrier contacts to semiconductors. These silicides are formed by thermal or laser sintering of the metal after deposition onto the substrate. Excess unreacted metal is removed by chemical etching. XPS has been used to show that the metal has been oxidized if the excess metal cannot be removed (52). 

Recently, RBS has been used to study the metal-silicon reactions induced by both a CW laser and an electron beam (53). Uniform, large area, single phase silicides were formed by adjusting the beam power level to induce a solid state reaction. Under certain conditions metastable mixed-phase systems were also obtained. RBS could non-destructively determine the stoichiometry of the phases formed without additional standards. AES and SIMS have also been used in the study of metal silicides. These applications and other points of interest in the fabrication, characterization and application of metal-semiconductor Schottky barrier junctions have been reviewed recently by Sharma and Gupta (54). 

Fig. 16. The J- V characteristics of a Pd/a-Si H Schottky-barrier diode before ( ) and after ISO C annealing ( ) to form a uniform silicide. The insert shows the improvement of the ideality parameter for annealing at various temperatures. [From Thompson et al. (1981).]...

Photoemissive Schottky detector (metal-silicide detector) Utilizes internal photoexcitation at a Schottky barrier, e.g., at PtSi... 

There is a continuing interest in metal silicide/silicon Schottky-barrier detectors. .. first... 

We consider the contact formed by TM silicides with silicon. The silicide layer is grown by solid state reaction of die TM and Si at high temperature. Outward diffusion removes contaminants from the interface in most cases, so that the silicide/silicon contact layer is clean and well defined, a critical aspect to obtain a reliable Schottky barrier height tkg. Metallurgical defects are the most common limitations of these junctions, as they are induced by the solid state reaction. The... 

Table 14.2 collects values of the Schottky barrier for silicide/silicon interfaces. 

Table 14.2 Schottky barrier values (eV) of metal silicides on n-silicon.

As RE metals are very reactive, the problem of oxidation of the metal before silicide formation is relevant The influence of an interfacial oxide layer on the Schottky barrier height of the Er and ErSi2 contacts on p-type silicon has been described [143], A correlation was found between the barrier height and the presence of an interfacial oxide layer. 

Metal silicides are widely used in microelectronic devices for the increase of the potential barrier height in metal-sUicon Schottky contact. Titanium silicide is favored for its low resistivity and thermal stability. IR spectroscopy is not typically used for investigation of metal silicides, because they do not have a characteristic and selective absorption in the IR range. Nevertheless, FTIR spectroscopy has been used to measure the thickness of Ti and titanium silicide films [274] as well as to monitor titanium silicide formation during the reaction of Ti films on a Si wafer [275]. 

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