Metal filament based organic memory device has unique advantages of long retention time and thermal stability. However, it has suffered from a large variation in the switching delay time (similar to 100 ms), in spite of the fast real switching time of hundreds nanoseconds. Among many possible reasons for the broad delay time, the effect of structural nonuniformity, in active area was mainly considered in this work. To solve this problem, we introduced an embossed structure into previous organic memory device, which significantly narrowed the distribution of the delay time. With this device, we could directly observe that the switching preferentially occurs at the summits of the embossed structure through optical microscope image. (c) 2007 Elsevier B.V All rights reserved.