Reactive ion etching of Al alloy and silicon dioxide films in a rotating magnetic field

Abstract

ABSTRACTA diode type magnetically enhanced reactive ion etching system was used for Al alloy films anda triode type magnetically enhanced reactive ion etching system was used for Si02 films. A same rotational permanent magnet was used for the diode and triode reactors. Excellent etching characteristics of TiN/Al.-l%Si-O.5%Cu/TiN and Si02 films were obtained at low pressure of about iPa.Simulations were also performed for drift motions of secondary electrons in the cathode sheath. With these results, we can easily understand etching characteristics and the charge build-up phenomena. 1.Introduction As gate channel width of DRAM FET is scaled down below O.5um, highly selective anisotropic dry etching without damage is required, and high rate etching with excellent uniformity is also neededto obtain high through-put in a single wafer system. Further, we have to etch the films in lowerpressure than 2OmTorr to avoide microloading effect. However, the plasma density decreases withlowering of the gas pressure, so that the etching rate also decreases. Addition of a magnetic field isusually used to retain the high plasma density in lower gas pressure. Several reactive ion etchingmethods applied the magnetic field have been examined1 -6) for the etching of 5i02, polysilicon