Method for improved metal fill by treatment of mobility layers

Abstract

A recess having a height-to-width aspect ratio from about 6:1 to about 10:1 in a semiconductor structure is taught with a method of forming the same. In a first embodiment, a refractory metal layer is formed in the recess, which can be a trench, a contact hole, or a combination thereof. A refractory metal nitride layer is then formed on the refractory metal layer. A heat treatment, preferably RTP, is used to form a metal silicide contact at the bottom of the contact hole upon semiconductor material. In a first alternative method, an ammonia high-temperature treatment is conducted to remove undesirable impurities within the refractory metal nitride layer lining the contact hole and to replace the impurities with more nitrogen. In a second alternative method, a second refractory metal nitride layer is formed by PVD upon the first refractory metal nitride layer. In either alternative, metallization layer is deposited with the recess. High pressure and temperature are used to substantially fill the recess with the metallization layer. In a preferred embodiment, deposition of the first refractory metal nitride layer is accomplished using trimethylethylenediamine tris (dimethylamino) titanium (TMEDT). The aspect ratio of a recess that can be substantially filled can exceed 8:1 when using a TMEDT-deposited refractory metal nitride layer and a subsequent deposition of a second refractory metal nitride layer by PVD. Following the substantially filling of the recess, residual surface metallization may be at least partially removed by such techniques as etch back or CMP.