Process dependence and characterization of Mo, Cr, Ti and W silicon Schottky diodes

This paper reports on the process dependence and electrical characterization of Schottky diodes and ohmic contacts fabricated on p- and n-type silicon wafers. Four metals are studied: Mo, Ti, W, and Cr due to their mid-gap barriers and compatibility with microelectronics processing. For these an original investigation of the variation in Schottky barrier height and contact resistance is carried out for the following process parameters: (i) pre-deposition wafer preparation, (ii) deposition method (sputtering and e-beam evaporation). (iii) deposition temperature for the sputtered samples, and (iv) annealing. It is found that RF-etching previous to metal deposition increases the contact resistance and the barrier height for diodes on p-type silicon. This is of great importance, since RF-etching is a very common in-situ cleaning process in microelectronic and MEMS technologies. Annealing can be used to restore the values of barrier height and contact resistance on wafers exposed to RF-etching