KR100390996B1 - Method for forming a metal line - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a metal wiring, and in particular, a barrier metal layer spacer is formed on an oxide sidewall defining a metal wiring, a nitride film is formed on the oxide film, and then an aluminum (Al) plug is formed in a subsequent process. Since a plug is formed, the margin of the via hole is increased by masking the nitride film, and the plug is formed of an aluminum layer having a better step coverage than tungsten (W) to form voids. It is characterized by improving the characteristics and yield of the device by reducing the via resistance, such as preventing the occurrence of void).

Description

Method for forming a metal line

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a metal wiring, and in particular, a barrier metal layer spacer is formed on an oxide film sidewall defining a metal wiring, and a nitride film is formed on the oxide film. The present invention relates to a metal wiring forming method for forming a plug to improve characteristics and yield of devices.

Semiconductor devices show an increase in the degree of integration every year, and the increase in the density is accompanied by a reduction in the area and size of each component of the device to meet various process constraints.

In the conventional metal wire forming method, as shown in FIG. 1A, a first interlayer insulating film 13 and a first photosensitive film (not shown) are sequentially formed on the semiconductor substrate 11.

And selectively exposing and developing the first photoresist layer so as to be removed only at a portion where a first plug contact is to be formed, and then selectively etching the first interlayer insulating layer 13 using the selectively exposed and developed first photoresist layer as a mask. To form a contact hole and remove the first photoresist film.

Subsequently, a first tungsten layer is formed on the first interlayer insulating layer 13 including the contact hole, and the first tungsten layer is polished by a chemical mechanical polishing method using the first interlayer insulating layer 13 as an etch stop layer. Thus, the first tungsten plug 15 is formed in the contact hole.

As shown in FIG. 1B, a first aluminum layer and a second photoresist layer (not shown) are sequentially formed on the first interlayer insulating layer 13 including the first tungsten plug 15.

And selectively exposing and developing the second photoresist film so as to remain only at a portion where the first metal wiring is to be formed, and selectively etching the first aluminum layer using the selectively exposed and developed second photoresist film as a mask to form a first metal wiring. After forming (17), the second photosensitive film was removed.

As shown in FIG. 1C, a second interlayer insulating film 19 and a third photosensitive film 20 are sequentially formed on the first interlayer insulating film 13 including the first metal wire 17.

And selectively exposing and developing the third photoresist film 20 so as to be removed only at a portion where a second plug contact is to be formed, and then using the selectively exposed and developed third photoresist film 20 as a mask for the second interlayer insulating film. Select 19 to etch to form a via hole.

At this time, a phenomenon (A) is misaligned during the via hole forming process so that the second interlayer insulating film 19 on one side of the first metal wire 17 is etched.

As shown in FIG. 1D, the third photosensitive film 20 is removed, a second tungsten layer is formed on the second interlayer insulating film 19 including the via hole, and the second interlayer insulating film 19 is used as an etch stop layer. The second tungsten layer is polished by a chemical mechanical polishing method to form a second tungsten plug 21 in the via hole.

In addition, a second aluminum layer 23 is formed on the second interlayer insulating layer 19 including the second tungsten plug 21.

Here, since the via holes are misaligned, the step coverage of the second tungsten plug 21 is poor, and voids B are generated in the second tungsten plug 21.

In the conventional metal wire forming method, a misalignment occurs during the via hole forming process on the lower metal wire, so that the interlayer insulating layer on one side of the lower metal wire is etched, and the step cover of the tungsten plug formed in the via hole is bad. As a result, voids increase and the via resistance increases, thereby deteriorating device characteristics.

The present invention has been made in order to solve the above problems, and since the barrier metal layer spacer is formed on the oxide sidewalls defining the metal wiring, the nitride layer is formed on the oxide layer, and then an aluminum plug is formed in a subsequent process, thus masking the nitride layer ( The purpose of the present invention is to provide a method for forming a metal wiring to increase the process margin (Margin), such as a via hole forming process, and to prevent the generation of voids by forming a plug into an aluminum layer having better step coverage than tungsten.

1A to 1D are cross-sectional views illustrating a method of forming a metal wiring according to the prior art.

2A through 2E are cross-sectional views illustrating a method of forming metal wirings in accordance with an embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

11 and 31: semiconductor substrate 13 and 33: 1st interlayer insulation film

15, 35: first tungsten plug 17: first metal wiring

19, 45: 2nd interlayer insulation film 20, 43: 3rd photosensitive film

21 second tungsten plug 23 second aluminum layer

37 oxide film 39 Ti / TiN layer spacer

41 nitride film 47 fourth photosensitive film

49: aluminum layer

The method of forming a metal wiring according to the present invention includes providing a lower structure including a first insulating film defining a metal wiring, forming a conductive layer spacer for metal wiring on the lower structures on both sides of the first insulating film, and the first insulating film. Forming a second insulating film, which is an etch protection film, on the first insulating film, forming a flat interlayer insulating film on the entire surface including the second insulating film, and selectively etching the interlayer insulating film to form a via hole, wherein the first insulating film is formed. And forming a plug to fill the via hole, wherein the interlayer insulating film remains only on the plug, and the plug is formed of a metal layer having better step coverage than tungsten.

When described in detail with reference to the accompanying drawings a preferred embodiment of the metal wiring forming method according to the present invention as follows.

2A through 2E are cross-sectional views illustrating a method of forming a metal wiring according to an embodiment of the present invention.

In the method for forming metal lines according to the embodiment of the present invention, as shown in FIG. 2A, the first interlayer insulating layer 33 and the first photoresist layer (not shown) are sequentially formed on the semiconductor substrate 31.

And selectively exposing and developing the first photoresist layer so as to be removed only at a portion where a first plug contact is to be formed, and then selectively etching the first interlayer insulating layer 33 using the selectively exposed and developed first photoresist layer as a mask. To form a contact hole and remove the first photoresist film.

Subsequently, a first tungsten layer is formed on the first interlayer insulating film 33 including the contact hole, and the first tungsten layer is polished by a chemical mechanical polishing method using the first interlayer insulating film 33 as an etch stop layer. Thus, the first tungsten plug 35 is formed in the contact hole.

As shown in FIG. 2B, an oxide film 37 and a second photosensitive film (not shown) are sequentially formed on the first interlayer insulating film 33 including the first tungsten plug 35.

And selectively exposing and developing the second photoresist film so as to remain only at a portion where the first metal wiring is to be formed, and selectively etching and etching the oxide film 37 using the selectively exposed and developed second photoresist film as a mask. After defining the formation site, the second photosensitive film is removed.

Subsequently, a Ti / TiN layer is formed on the first interlayer insulating film 33 including the oxide film 37, and the Ti / TiN layer is etched back to form Ti / TiN layer spacers 39 on both sides of the oxide film 37. To form.

Here, the Ti / TiN layer spacer 39 serves as a metal wiring.

As shown in FIG. 2C, the nitride film 41 and the third photosensitive film 43 are sequentially formed on the entire surface including the Ti / TiN layer spacer 39.

Then, the third photoresist layer 43 is selectively exposed and developed so as to remain only above the oxide layer 37, and the nitride layer 41 is selectively etched using the selectively exposed and developed third photoresist layer 43 as a mask. .

As shown in FIG. 2D, the third photoresist layer 43 is removed, and the second interlayer insulating layer 45 and the fourth photoresist layer 47 are sequentially formed on the entire surface including the nitride layer 41.

And selectively exposing and developing the fourth photoresist film 47 so as to be removed only at the portion where the second plug contact is to be formed, and then using the selectively exposed and developed fourth photoresist film 47 as a mask for the second interlayer insulating film. Select 45 to etch to form a via hole.

In this case, the oxide layer 37 is prevented from being etched by masking the nitride layer 41 when a misalignment occurs in the via hole forming process.

As shown in FIG. 2E, the fourth photoresist layer 47 is removed, an aluminum layer 49 is formed on the second interlayer insulating layer 45 including the via hole, and the second interlayer insulating layer 45 is etched away. The aluminum layer 49 is planarized and etched by a chemical mechanical polishing method.

Here, the aluminum layer 49 on the nitride film 41 may serve as a plug, and may be formed of a copper (Cu) layer instead of the aluminum layer 49.

In the metal wire forming method of the present invention, since the barrier metal layer spacer is formed on the oxide film sidewalls defining the metal wires, a nitride film is formed on the oxide film, and an aluminum plug is formed in a subsequent process, a via hole forming process is performed as a masking role of the nitride film. By increasing the process margin of the and forming a plug with an aluminum layer having better step coverage than tungsten to prevent voids, the via resistance is reduced, thereby improving the characteristics and yield of the device.

Claims (3)

Providing a lower structure having a first insulating film defining a metal wiring; Forming a conductive layer spacer for metal wiring on lower structures on both sides of the first insulating layer; Forming a second insulating film, which is an etch protection film of the first insulating film, on the first insulating film; Forming a flat interlayer insulating film on the entire surface including the second insulating film; Selectively etching the interlayer insulating film to form a via hole, wherein the interlayer insulating film remains only on the first insulating film; And forming a plug to fill the via hole, wherein the plug is formed of a metal layer having better step coverage than tungsten. The method of claim 1, And forming the conductive layer spacer as a Ti / TiN layer spacer. The method of claim 1, And forming the metal layer as one of an aluminum layer and a copper layer.