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Static magnetron triode reactive ion etching (SMTRIE) has been developed as a new method that achieves high-rate and high-uniformity etching with low metal oxide semiconductor (MOS) damage. An overview of the method is provided together with an application to Al-Cu etching. Four axisymmetric coils produce radial magnetic flux near and parallel to the etching cathode, and cylindrical magnetic flux parallel to the surrounding side cathode. This field creates a magnetron-type discharge near both cathodes, thus producing high plasma density that is both axisymmetrically and radially uniform. Al-Cu etching results demonstrate the excellent uniformity of SMTRIE. In addition, no gate damage was observed even at high power or under relatively poor uniformity. SMTRIE is one of the most promising etching methods for application to deep submicron geometries where precise and low-damage etching are indispensable.

We describe a new Al-Cu alloy etching system that uses aluminum chloride formed in the reactor to build deep-submicron Al-Cu laminated interconnections. The etching residue containing copper chloride after Al-Cu etching can be removed by a flow of aluminum chloride at a relatively low temperature of 120°C. This is because copper chloride reacts with aluminum chloride to form volatile chloroaluminate copper. In the new etching system aluminum chloride is formed through the use of a second cathode covered with aluminum targets in static magnetron triode reactive ion etching (SMTRIE). With this configuration, aluminum chloride flow can be precisely controlled and highly selective deep-submicron etching of Al-Cu laminated interconnections without any residue can be achieved. It is also shown that the aluminum chloride flow suppresses after-corrosion.