The physics aims of future lepton colliders such as CLIC pose challenging demands on the performance of the detector system. In particular, the vertex and tracking detectors have to combine a spatial resolution of a few micrometres and a low material budget with a few nanoseconds time-stamping accuracy. To address these requirements a broad R&D programme on silicon detector technologies is pursued within various collaborative frameworks such as the CERN EP R&D program, AIDAinnova and the CLICdp collaboration. For the vertex detector, fine-pitch hybrid pixel detectors with dedicated 65nm readout ASICs as well as hybridisation techniques using solder bumps or anisotropic conductive films are explored. Fully-integrated monolithic CMOS sensors are under investigation for the large-surface CLIC tracker. This seminar gives an overview of the CLIC vertex and tracking detector R&D, focussing on recent results from test-beam campaigns and simulation-based sensor optimisation studies.