Micro-cleavage method for specimen preparation

Abstract

A micro-cleavage method for preparing a semiconductor specimen for examination by an optical or electron microscopic is disclosed. The method can be carried out by hand and thus no expensive equipment such as a polishing machine is necessary. In the method, at least two bird's beak marks are cut in a top surface of a silicon wafer that contains a target, i.e., a defect or a circuit to be examined. The bird's beak marks are formed by a wide scribe line and a narrow scribe line overlapped together. The wide scribe line of the bird's beak mark is used for visual alignment with the edge of a rigid substrate, while the fine scribe line is utilized for initiating a crack when a bending stress is applied on the bird's beak mark. The bird's beak mark can be made by using a laser cutter after a wafer slice which contains the target area is first cleaved by mechanical means such as a diamond knife. A first bird's beak mark is formed at the cleaved edge of the slice and a second bird's beak mark is formed with its fine scribe line oriented toward the target. When a bending stress is applied on the top surface of the silicon slice, stress concentrates on the bird's beak marks and creates a fine crack to propagate along a crystallographic plane in the wafer toward the target thus exposing the target in a fractured surface.