In-line voltage contrast determination of tunnel oxide weakness in integrated circuit technology development

摘要

A method for determination of tunnel oxide weakness is provided. A tunnel oxide layer is formed on a semiconductor wafer. At least one poly gate is formed on the tunnel oxide layer in a flash memory region of the semiconductor wafer. At least one poly island, which is substantially larger than the poly gate, is formed on the tunnel oxide layer in a voltage contrast cell region of the semiconductor wafer. The poly island and the tunnel oxide layer therebeneath form a voltage contrast tunnel oxide cell. A voltage contrast measurement is performed on the voltage contrast tunnel oxide cell. The voltage contrast measurement is then compared with prior such voltage contrast measurements on other such voltage contrast tunnel oxide cells. The tunnel oxide weakness of the tunnel oxide layer is then determined from the voltage contrast measurement comparisons.