Method of reactive ion etching of a thin copper film

Abstract

Abstract The method to etch an electrically conductive film comprises the steps of: forming a metal conductor film comprising copper or copper alloy, upon a substrate; and forming a mask pattern upon the metal conductor film; and etching an exposed part of the metal conductor film by the use of the mask pattern and a reactive ion-etching (RIE) employing a plasma of a gas mixture comprising a silicon tetra-chloride (SiCl 4 ) gas, a nitrogen (N 2 ) gas and a carbon compound gas, so that the exposed part of the metal conductor film is removed so as to leave the masked part. The metal conductor film may further comprise a diffusion protection layer formed of a refractory metal or its alloy upon and/or underneath the copper/mainly-copper layer. The mask pattern may be typically formed of silicon dioxide (SiO 2 ). The substrate may further comprise an insulating layer thereon, typically formed of silicon dioxide (SiO 2 ), for contacting said metal conductor film. The carbon compound gas may typically be a carbon tetra-chloride (CCl 4 ), methane (CH 4 ), ethane (C 2 H 6 ) or propane (C 3 H 8 ) and so on. When SiCl 4 is employed the content may typically be 6.6 to 15% by volume in the gas mixture. When methane (CH 4 ) gas is employed the content may typically be 8 to 18% by volume in the gas mixture. The etching step may preferably performed at a substrate temperature higher than 250° C.

Inventors

• 👤 Takatoshi Hirota

Bibliographic Details