Method for forming metal interconnection of semiconductor device

#This application claims the benefit of Korean Patent Application No. 10-2004-0114635, filed on Dec. 29, 2004, which is hereby incorporated by reference for all purposes as if fully set forth herein.

#1. Field of the Invention

#The present invention relates to metal interconnection formation in semiconductor devices, and more particularly, to a method for forming a metal interconnection of a semiconductor device, in which, in a single damascene process using lower and upper inter-metal dielectric (IMD) films, a nitridation layer is thinly deposited and annealed before forming a trench in the upper IMD film. This obtains a constant trench depth by avoiding over-etching or under-etching when forming the trench, thereby preventing the occurrence of openings and voids in a copper interconnection.

#The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:

#FIG. 1A is a cross-sectional view of a metal interconnection of a semiconductor device formed according to a related art method, illustrating an under-etching condition;

#FIG. 1B is a cross-sectional view of a metal interconnection of a semiconductor device formed according to a related art method, illustrating an over-etching condition; and

#Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, like reference designations will be used throughout the drawings to refer to the same or similar parts.

#Referring to FIG. 2, illustrating a method for forming a metal interconnection of a semiconductor device according to the present invention, a contact hole is formed in a first IMD film 201 formed of silicon on a semiconductor substrate (not shown), and the contact hole is filled with a tungsten plug 202. A nitridation layer is formed on the first IMD film 201 by primary annealing under an ambient of nitrogen, thereby forming nitride films 203 and 204. Namely, a silicon nitride film 203 is formed on the surface of the first IMD film 201 and a tungsten nitride film 204 is formed on the surface of the tungsten plug 202.

#During an etching of an trench, the nitride films 203 and 204 serve as a “self-stop” layer but, due to their high dielectric constants, slow the operating speed of the device. Therefore, it is preferable that the nitride films 203 and 204 are thinly formed by annealing or primary annealing to minimize their dielectric constants. In an embodiment, the primary annealing is performed at a temperature between 200° C. and 700° C. using a rapid thermal process or a furnace. Nitrogen (N2), anhydrous ammonia (NH3), or a material that can be nitrified with a lower layer may be used as the nitridation layer.