In this work we present a method for the fabrication of silicon microtips with self-aligned anodes in order to obtain field emitting devices. The method is based on the anisotropic corrosion of the silicon substrate in KOH solutions and utilizes low stress SiO x N y films obtained by PECVD as masking material. These films are also utilized as structural material for mechanical support and electrical insulation of the electrodes. For the electrodes sputtered Cr films are utilized. Optical microscopy was utilized to determine the etch rate of the different stages during the microtip formation, in order to enable us to ascertain the total development time versus the initial mask dimensions. Matrixes with different number of microtips, 52 µm height and with diameter at the vertex bellow 1 µm, were fabricated and characterized. The results also show that the low stress SiO x N y film is essential to endure the corrosion process without structural damage.