Accession Number:

ADA210282

Title:

The Effects of 'Normal' Annealing Cycles During IGFET Fabrication on Initial and Radiation Induced Gate Insulator Defects

Descriptive Note:

Annual progress rept. 1 Dec 1988-7 Jul 1989

Corporate Author:

MICROELECTRONICS CENTER OF NORTH CAROLINA RESEARCH TRIANGLE PARK

Personal Author(s):

Report Date:

1989-07-13

Pagination or Media Count:

15.0

Abstract:

The influence of three typical annealing cycles normally used in IGFET processing on as-fabricated and post-irradiated gate oxide defect levels was studied. These cycles were 1 post-oxidation for 5 minutes at 1000 C in argon, 2 post-polysilicon for 30 minutes at 500 C in forming gas, and 3 post-metallization for 30 minutes at 400 C in hydrogen. Gate oxide defects were characterized using optically assisted electron injection of n-channel polysilicon-gated IGFET devices. It was found that the presence or absence of any of the three annealing cycles during the processing had no effect on measured interface state and bulk oxide defect levels in the as-fabricated devices. Following exposure to Al K alpha X-ray radiation, the increase in the number of bulk oxide defects was found to be independent also of the presence or absence of any of the cycles. The interface state density was found to increase only slightly following irradiation, with the smallest increase occuring for devices which had received either the post-oxidation or the post-metal anneal. These results may indicate that other high temperature steps which are present in IGFET processing, as well as the use of different electrode materials than were employed in the earlier studies overshadow the effects of the three annealing cycles studied, and therefore, the entire processing sequence of IGFET fabrication must be considered in determining the factors which influence gate insulator defect levels and susceptibility to ionizing radiation.

Subject Categories:

  • Solid State Physics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE