1. A method of detecting a buried defect in a target microscopic metal feature, the method comprising: configuring an imaging apparatus to impinge charged particles with a landing energy such that the charged particles, on average, reach a depth within the target microscopic metal feature; configuring the imaging apparatus to filter out secondary electrons and detect backscattered electrons; operating the imaging apparatus to collect the backscattered electrons emitted from the target microscopic metal feature due to impingement of the charged particles; and comparing a backscattered electron (BSE) image of the target microscopic metal feature with the BSE image of a reference microscopic metal feature to detect and classify the buried defect.