A 2500 Ω / □ tantalum thin film resistor for silicon integrated circuits

The ability to utilize very high sheet resistivities is one of the advantages of using thin film resistors on silicon integrated circuits. This paper discusses a process which produces a film having a sheet resistivity of 2500 Ω/□. an order of magnitude higher than current typical thin films. Five-megohm resistors have been fabricated on 12 × 20 mil areas. These resistors have TCR´s of -250 to -350 ppm and exhibit elevated temperature aging stability comparable to that reported for tantalum films having much lower resistivities. This stability is obtained without the addition of a further protective coating.