FABRICATION OF ON-CHIP BARIUM STRONTIUM-TITANATE CAPACITORS BY METALLOORGANIC DECOMPOSITION

Metallo-organic thin film decomposition (MOD) was used in forming bari um strontium titanate (BST) thin film capacitors on phosphorus doped p olysilicon films deposited on 4 in. silicon wafers, A single step depo sition process yielded highly uniform, crack-free BST films ranging up to 0.25 mu m in thickness and having various step heights and dimensi onal area. Scanning electron microscopy (SEM) showed very good step co verage and planarization of the BST, The capacitors had capacitance de nsities above 200 nF/cm(2), leakage current densities less than 1.55 m u A/cm(2) at a bias voltage of 10 V, and a dielectric breakdown field above 1 MV/cm, Small temperature coefficients of capacitance and dissi pation (tan delta) were also observed, Frequency response measurements were made using the BST capacitors and on-chip resistors in low pass and high pass circuit configurations. A plot of relative gain and phas e angle versus frequency showed excellent agreement with predicted res ults.