NONDESTRUCTIVE INTERNAL OBSERVATION AND DISTRIBUTION OF POTENTIAL WITH BIAS APPLICATION OF NPN SI DARLINGTON TRANSISTOR CHIP USING ELECTRON-ACOUSTIC MICROSCOPY

Study of an npn Si Darlington transistor chip under bias application w as carried out using electron-acoustic microscopy (EAM). The results w ere as follows. (1) The distribution of potential in the chip with app lied bias voltage could be determined. (2) The acceleration voltage (H V) of the irradiating electron beam was the major factor which determi ned the observable depth (t(x)) by EAM. (3) t(x) corresponded to appro ximately 60% of the range of excited electrons as a function of HV. Th us, EAM could nondestructively provide information on the internal str ucture of the device in the operating condition of the chip. The above results could not be obtained from the scanning electron microscopy ( SEM) mode images.