Distinguishing Failure Modes in a Bipolar Device
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
Testing methods have been developed to distinguish the failure modes of a transistor pipe from the failure mode due to the lack of connection between the extrinsic and intrinsic base regions of a transistor. The methods are convenient and nondestructive. For the advanced transistor with extrinsic and intrinsic bases processed separately, a link-up problem can occur between these two base regions. When the lateral diffusions are insufficient or the sidewall is too wide, the two base regions 2 and 1 are separated and are not linked up or connected together, as shown in Fig. 1. The device becomes defective, and the intrinsic base 1 is inaccessible from the external land or pad. The extrinsic base 2 is connected to the external land, but it is isolated from the emitter and the collector of the transistor.