A high performance pyroelectric infrared sensor array based on epitaxially grown Pt and La-modified PbTiO3(PLT) thin films is fabricated by RF magnetron sputtering and micromachining technology. A single detector element forms a ferroelectric thin film capacitor epitaxially grown on a single crystal MgO substrate. The heat loss and the noise level are minimized by etching the substrate that leads to reduced thermal mass. Micromachining technology is used to support the fragile MgO substrate membrane by coating polyimide on top of the detector elements. The sensor array is mounted on a dip-type package sealed by a Silicon filter with anti-reflection coating to transmit 8–10 μm wavelength infrared radiation from a human body. It shows a very high detectivity of 8.5 ×108cm·√Hz/W and it is primarily due to the highly c-axis oriented epitaxially grown PLT thin film capacitor with the minimized thermal mass.