US 6,274,486 B1Granted

Metal contact and process

AssigneeMicron Technology, Inc.

InventorsHoward E. Rhodes, Sanh Tang

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Abstract

Structures and processes are disclosed for reducing electrical contact resistance between two metal layers. Specifically, a resistive aluminum oxide layer forms spontaneously on metal lines including aluminum, within a V-shaped contact via which is opened in an insulating layer through a mask. The mask includes an opening with a width of less than about 0.75 μm. After removing the mask, the via is treated with an RF etch. The resultant contact has a width at the bottom of less than 0.9 μm. A titanium layer of 300 Å to 400 Å is deposited into the via, with about 60 Å to 300 Å reaching the via bottom and reacted with the underlying aluminum. The reaction produces a titanium-aluminum complex (TiAlx) with a thickness of about 150 Å to 900 Å. Advantageously, this composite layer provides a low resistivity contact between the aluminum-containing layer and a subsequently deposited metal layer.

Claims8

Dependent claims

A method of forming an integrated circuit including a low resistivity intermetal contact through an insulating layer, comprising:

forming a first conductive layer comprising aluminum over a semiconductor substrate, said first conductive layer having an upper surface;
forming an insulating layer on the upper surface;
etching a contact via with a selected size and shape in the insulating layer, thereby exposing a contact region of the upper surface, said first conductive layer including an aluminum oxide layer at least within the contact region of the upper surface;
determining an amount of titanium to deposit over the insulating layer to form between 60 Å and 300 Å of titanium over the contact region of the contact via with the selected size and shape;
depositing the determined amount of titanium over the insulating layer and into the contact via;
reacting said titanium with the aluminum of said first conductive layer to form a composite material within said contact region;
and
depositing a second conductive layer into the contact opening.

5 more elements

Dependencies are inferred from the claim text.