EVALUATING THE MINIMUM THICKNESS OF GATE OXIDE ON SILICON USING FIRST-PRINCIPLES METHOD

The continuing reduction in integrated circuit element size results in contemplating physical structures with dimensions in which an atomist ic picture becomes important. So far, an essential element responsible for the ever-shrinking device is the feasibility of reducing the SiO2 gate insulator thickness from one technology generation to another. U sing a first-principles pseudopotential approach, we made such an atte mpt to evaluate the minimum thickness of SiO2 on Si substrate at which a proper barrier height between SiO2 and Si holds. This was done by s tudying the band offset between SiO2 and Si as a function of SiO2 thic kness. The SiO2/Si(100) interface structure is constructed between bet a-cristobalite SiO2 layer and Si(001), Three superlattices containing two, four and eight layers of SiO2 are considered. Based on the fact t hat the band offsets reach a saturation value after approximately 7 An gstrom of SiO2 thickness, we estimate that the minimum gate oxide thic kness is 7 Angstrom. (C) 1998 Elsevier Science B.V. All rights reserve d.