Semiconductor device having a multi-layer metal contact

Abstract

A wiring layer of a semiconductor device having a novel contact structure is disclosed. The semiconductor device includes a semiconductor substrate, an insulating layer having an opening (contact hole or via) and a first conductive layer formed on the insulating layer which completely fills the opening. The first conductive layer does not produce any Si precipitates in a subsequent heat-treating step for filling the opening with the first conductive layer material. The semiconductor device may further include a second conductive layer having a planarized surface on the first conductive layer. This improves subsequent photolithography. An anti-reflective layer may be formed on the second conductive layer for preventing an unwanted reflection during a photo lithography process. The semiconductor device preferably includes a diffusion barrier layer under the first conductive layer and on the semiconductor substrate, on the insulating layer, and on the inner surface of the opening which prevents a reaction between the first conductive layer and the semiconductor substrate or the insulating layer. A method for forming the wiring layer is also disclosed. Providing a semiconductor device with the wiring layer reduces the leakage current by preventing an Al spiking. Since the first conductive layer undergoes a heat-treatment step at a temperature below the melting point, while flowing into the opening and completely filling it with the first conductive layer material, no void is formed in the opening. Good semiconductor device reliability is ensured in spite of the contact hole being less than 1 .mu.m in size and having an aspect ratio greater than 1.0.