Potential of air gap technology by selective ozone/TEOS deposition: Effects of air gap geometry on the dielectric constant

Air gaps offer an interesting alternative to low-k or ultra-low-k materials in order to reduce the line-to-line capacitance in a metallization system. A possible approach for air gap fabrication is based upon selective ozone/TEOS deposition. Feasibility of this method will be shown and capacitance reductions by almost 50% will be demonstrated. The potential for further reduction can be scanned by theoretical modelling of the line-to-line capacitance. The results indicate that effective k values below 2 are reachable by air gaps even if conventional materials like oxide and nitride are used in the process.