Measurement of submicrometric intrinsic spatial resolution for active pixel sensors

To measure the intrinsic spatial resolution of silicon pixel sensor is usually a non-trivial task, particularly for small pixel sizes where the multiple scattering may be the limiting factor. In this work, we present a new measurement technique to obtain the intrinsic spatial resolution of silicon active pixel sensors. The method relies on the capability of the device to record the passage of a charged particle, incoming at a grazing angle, over several tens or hundreds of pixels, acting as a solid state ionization chamber and thus defining a track. The track will then be fitted by a line and the intrinsic spatial resolution will be obtained using two methods: i) extracted by the sigma of the fit; ii) defining a telescope-on-chip configuration to find a residual distribution. Comparison with a more traditional measurement ( telescope configuration) and a discussion on the limit of this technique, when the pixel size shrinks, will also be presented.