A method of fabricating an image sensor on a semiconductor substrate having a sensor array region is described. A first planar layer is formed on a semiconductor substrate. Then, a color filter array (CFA) is formed on the first planar layer. A second planar layer is formed on the color filter array. Thereafter, a plurality of U-lenses is formed on the second planar layer. A passivation is formed over the second planar layer and the U-lenses by performing a plasma-enhanced chemical vapor deposition (PECVD) process using TEOS gas. The passivation layer is formed under the conditions that include applying radio frequency power at a rating between 250W.about.450W and supplying TEOS gas at a mass flow rate of about 150.about.500 mg/m.