A Study of Silicon Oxide Growth Mechanisms for the Purpose of Identifying Hardness Assurance Total Dose Screens.
AIR FORCE WEAPONS LAB KIRTLAND AFB N MEX
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Processes exist today which will produce oxide layers on silicon semiconductor devices with total ionizing surface effects sufficiently suppressed to satisfy military needs. There remains the problem of assuring that the devices produced by these processes on a production line are indeed hard to surface effects, i.e., an unintended variation in processing has not reduced hardness. Some sort of acceptance test, called a hardness assurance screen, is needed. To identify possibilities for these tests, the literature was searched, analyses were performed, and special wooden ball molecular models were studied. The current model of oxide layer growth and the relations of such growth to total dose susceptibility were gleaned from the literature. This model was extended by the study as follows Qss is caused by an oxygen atom which is bonded to three interface silicon atoms. This produces an interface donor state whose energy is above the silicon conduction band. Nss is primarily caused by a Si-0-Si bond in which the oxygen has been removed leaving a stretched Si-Si bond. This produces two interface states a donor level near the valence band and an acceptor level near the conduction band.
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