Threshold optimization for SOI transistors through use of negative charge in the gate oxide.

摘要

Threshold optimization for SOI transistors is achieved through the formation of a layer of charge (21) within the gate oxide (14), which layer has a polarity corresponding to that of the ion implantation (22) for threshold voltage control. A negative charge layer (21) is formed by furnishing trace amounts of aluminum on the substrate before growth of an oxide to form a portion of the gate oxide. The aluminum will form a charge layer (21) on the surface of the oxide (19) and an additional oxide (18) is then deposited on the same to form the gate oxide as a sandwich with the charge layer in the same.