Method for forming a via plug in a semiconductor device

Abstract

A method of forming a via plug in a semiconductor device is disclosed. Metal nuclei are formed on the surface of the metal layer underlying the via hole. The metal layer, which is partially exposed between metal nuclei, is etched by means of a wet etching method, and accordingly, a plurality of etching grooves is formed on the partially exposed surface of the metal layer. As a result, the formation of such grooves has the effect of increasing the bottom surface area of the via hall, thereby increasing the adhesive strength to a contact surface of the via hall and decreasing the via resistance.

Description

Similar reference characters refer to similar parts throughout the several views of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1A through 1E are cross sectional views illustrating steps forming a via hole in a semiconductor device according to the present invention.

Referring to FIG. 1A, a first metal layers 2 are initially formed on the substrate 1 in such a way so as to be isolated from each other. The first, second and third insulating layers 3, 4 and 5 are sequentially formed on the resulting substrate and then the third insulating layer 5 is planarized.

Referring to FIG. 1B, a desired portion of the first, second and third insulating layers 3, 4 and 5 situated on top of the first metal layers 2 are sequentially etched using the wet etching or dry etching method in order to connect to a second metal layer which will be formed in a later process, and thereby forming via holes 6 the aspect ratios of which are different from each other.

Referring to FIG. 1C, the via holes 6 are pretreated by the dry etching method in the RIE (Reactive Ion Etch) reactor during approximately one (1) minute using a NF₃, SF₆ or Ar sputter. Metal such as a tungsten(W), aluminum(Al), copper(Cu), molybdenum(Mo), titanium(Ti), cobalt(Co), or chromium(Cr) is then selectively deposited on the surface of the first metal layer 2 underlying the via holes 6 for a duration of approximately one (1) minute in the metal depositing reactor, thereby forming metal nuclei 7. The magnitude of the metal nuclei diameter is approximately 500 to 1000 Å. When the via holes 6 are pretreated, a fluorine particle compound and a native oxide layer is generated.

Referring to FIG. 1D, the first metal layer partially exposed between the metal nuclei 7 is etched by the wet etchant such as BOE (Buffered Oxide Etchant) in such a way that the metal nuclei 7 remains, and thereby forming a plurality of etching grooves 8 on the surface of the first metal layer 2. The wet etchant's etching selectivity is greater for the first metal layer 2 than it is for the metal nuclei 7.

As the wet etching method forms etching grooves 8 on the surface of the partially exposed metal layer, the contact area is increased and a fluorine particle compound, and native oxide layer are removed. As a result, when the via plug is formed on the via hole, the adhesive strength is increased while the via resistance is decreased.

Referring to FIG. 1E, a via plug 9 is formed on the via holes 6 using a LPCVD reactor, and then a second metal layer 10 is formed to connect with the via plug 9.

As described above, according to the present invention, metal nuclei are formed on the via hole and then etching grooves are formed on the partially exposed metal layer under the via hole to increase the area of contact for connection with the via plug. Accordingly, the removal of particles which contribute to the increased via resistance results in a decrease of via resistance and improves the adhesive strength thereof. As a result, the electrical connection characteristic of the semiconductor device is improved.

Although this invention has been described in its preferred embodiment with a certain degree of particularity, one skilled in the art would know that the preferred embodiment disclosed here is only an example and that the construction, combination and arrangement of its parts may be varied without departing from the spirit and the scope of the invention.