High-performance vertical-power DMOSFETs with selectively silicidedgate and source regions

A power FET (field-effect transistor) structure with selectively silicided gate and source region is described. This structure simultaneously lowers the gate sheet-resistance and the source contact resistance. The gate-source isolation was provided by plasma etching conformally deposited chemical vapor deposition (CVD) oxide using a photoresist mask. This structure has resulted in an order of magnitude improvement in the gate sheet resistance and about 25% improvements in the device's on-resistance (the resistance when conducting in the on-state) compared to previously reported nonsilicided conventional power FETs. Extremely low-resistance Al-TiW-TiSi₂ metallurgy with in situ sputter etching of the silicide surface prior to TiW deposition contributed to the reduction in the on-state resistance. Vertical-power DMOSFETs (double-diffused MOSFET) fabricated using this technology have a specific on-resistance of 0.53 Ω cm² for devices capable of blocking 50 V in the off state