Sacrificial oxygen sources to prevent reduction of oxygen containing materials

Abstract

Abstract Some VLSI fabrication steps can cause degradation of the useful properties of many high dielectric constant materials that will likely be used in future high density integrated circuit devices. The presence of hydrogen, for example, can readily reduce (i.e. remove oxygen from) oxygen-containing dielectric materials. In general, there exists a critical oxygen activity value below which an oxygen-containing dielectric material will become conductive or otherwise unacceptable. Reduction of the oxygen-containing material during VLSI processing is prevented by providing a nearby sacrificial source of oxygen. Generally, the oxygen source is reduced to a lower oxidation state (i.e. the material loses oxygen) at an oxygen activity level that is larger than the critical oxygen activity value. The required placement of the oxygen source material relative to the oxygen-containing dielectric material is in general determined by the requirement that the oxygen partial pressure over the entire volume of the oxygen-containing dielectric material not fall below the critical value during subsequent VLSI processing steps. The presence of these sacrificial oxygen source materials (e.g. 56) elevates the partial pressure of oxygen in the vicinity of the oxygen-containing dielectric material (e.g. barium strontium titanate 46) such that the oxygen partial pressure during subsequent fabrication steps does not fall below the oxygen partial pressure at which the oxygen-containing dielectric material is reduced. Structures wherein the sacrificial oxygen sources are part of capacitor electrodes (e.g. RuO2 44) are presented, as well as structures wherein volumes of sacrificial oxygen source materials 56 are formed nearby to integrated circuit capacitors.

Inventors

• 👤 Scott R. Summerfelt

Bibliographic Details