Radiation-hard COS/MOS devices incorporating undoped (dry) SiO2 channel dielectric

The objective of this program is to define a 'dry oxide' process for the production of COS/MOS (CD4000 series) on bulk-silicon integrated circuits which simultaneously meets the demands of radiation hardness, producibility, and reliability. This process will use undoped (clean) SiO2 as the channel dielectric. During this study a matrix of silicon processing (6 runs of 10 wafers of the CD4023, and 6 runs of 10 wafers of the CD4049X) was completed. Seven of the runs completed under this matrix fit within the window of what will be the recommended 'Rad-Hard' pilot process. All seven of these runs exhibited radiation tolerance in excess of 1,000,000 rads total dose, with several runs operational past 3,000,000 rads. Devices so produced were tested too and found to meet both the commercial and the MIL-STD-883A 'hi-rel' specifications with good yields. Accelerated life testing was done on all twelve runs, and all exhibited excellent stability.