A NEW APPROACH FOR DIRECT OBSERVATION OF BASE WIDTH MODULATION IN VERTICAL BIPOLAR-TRANSISTORS

A new de measurement technique that allows direct observation of the f orward and reverse Early effects is described. The technique employs a special test structure and is used to accurately determine the Early voltage parameters in the Gummel-Poon model, The improvements provided by this method over existing parameter extraction techniques are real ized by using a direct measurement of the normalized base charge as a function of the emitter and collector junction biases, The new techniq ue described here allows the Early voltage parameters to be extracted as a function of applied bias in a straightforward manner and is suita ble for high volume measurements for statistical characterization and for process monitoring in an industrial setting.