Utilization of disappearing silicon hard mask for fabrication of semiconductor structures

Abstract

A method of forming structures in semiconductor devices through a buffer or insulator layer comprising the use of a silicon hard mask between a patterned resist layer for etching the structures and an underlying barrier layer. The silicon hard mask acts as a backup to the resist layer, preventing the potential etching of the barrier layer which is protected by the resist layer by acting as an etch stop if the first resist layer is ablated away during the etching of the openings for the structures. This allows for a thinner layer of resist material to be used because no additional resist is required to provide a “margin of error” during the etching to assure the integrity of the barrier layer. After etching, a layer of silicidable material is deposited over the silicon hard mask and the resulting structure is annealed to turn the silicon hard mask into a silicide material. The silicide material is removed by an abrasive method, such as by CMP. A silicon hard mask is difficult to remove by such an abrasive method. However, a silicide material is conducive to abrasive removal. The deposition and annealing of the silicidable material can be a part of the formation of a contact silicide layer at the bottom of a contact opening during the formation of a bitline contact or a capacitor contact.