Inverted-pyramid silicon nanopore arrays are realized with a well-controlled, three-step, anisotropic wet etching process with different KOH bath temperatures. The influence of etchant concentration and temperature on the etching rate is investigated. Nanopore arrays with an average size of 100 nm and individual nanopores with feature sizes as small as 30 nm were successfully fabricated at low cost using this method. This study paves the way toward the controllable, large-scale production of arrays of inverted-pyramid nanopores with desired size.