KR19980055903A - Via hole formation method of semiconductor device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a via hole in a semiconductor device, and to forming a protective film on a sidewall of a via hole in order to prevent loss of the SOG film generated when the photoresist film is removed. A method of forming a via hole is provided.

Description

Via hole formation method of semiconductor device

The present invention relates to a method of forming a via hole of a semiconductor device, and more particularly, to a method of forming a via hole of a semiconductor device to improve a step coverage of a metal.

In general, in the process of manufacturing a semiconductor device, the metal layer is formed in a double or multiple structure. In addition, an intermetallic insulating film is formed between the metal layers to insulate and planarize, and a connection between the metal layers is made through a via hole formed in the intermetallic insulating film. However, as the semiconductor device is highly integrated, the size of the via hole is reduced, so that the process of embedding the metal in the via hole becomes difficult, and the contact resistance between the metal layers is increased. The via hole forming method of the conventional semiconductor device will now be described with reference to FIGS. 1A to 1C.

1A to 1C are cross-sectional views illustrating a method of forming a via hole of a conventional semiconductor device, and FIG. 1A is a top view of an entire upper surface after a metal wiring 3 is formed on a silicon substrate 1 on which an insulating film 2 is formed. On the metal interlayer insulating film 7 is formed a metal interlayer insulating film 7 in which a first oxide film 4, a spin-on-glass film 5, and a second oxide film 6 are sequentially stacked. It is sectional drawing of the state which patterned the said photosensitive film 8 after forming the photosensitive film 8.

FIG. 1B illustrates wet etching the metal interlayer insulating film 7 in an exposed portion by using the patterned photoresist 8 as a mask, and then dry etching the metal interlayer insulating film 7 having the remaining thickness. It is sectional drawing of the state which the via hole 9 was formed so that the wiring 3 might be exposed.

FIG. 1C is a cross-sectional view of the photoresist layer 8 removed using an oxygen (O ₂ ) plasma, wherein the exposed SOG film 5 of the sidewall (part A) of the via hole 9 is formed of the oxygen (O) plasma plasma. O ₂ ) Bowing phenomenon that is lost by the plasma is generated. In this bowing phenomenon, the volume of the SOG film 5 increases as carbon dioxide (CO ₂ ) generated by the reaction of carbon contained in the SOG film 5 and oxygen (O ₂ ) is discharged to the outside. This is caused by a decrease, which leads to a poor shape of the sidewalls of the via hole 9, resulting in an increase in the level of the metal layer in the via hole 9.

Accordingly, an object of the present invention is to provide a method of forming a via hole in a semiconductor device which can solve the above-mentioned disadvantages by removing the photosensitive film after forming a protective film on the sidewall of the via hole.

According to an aspect of the present invention, a method of forming a via hole of a semiconductor device for exposing a predetermined portion of a metal wiring after forming an interlayer insulating film on a silicon substrate on which a metal wiring is formed, is provided on the interlayer insulating film. Forming a photoresist film and then patterning the photoresist; forming a via hole to expose the metal wiring by etching the interlayer insulating film by an etching process using the photosensitive film patterned from the step as a mask; And forming a protective film on the sidewalls of the via holes, and then sequentially removing the photoresist film and the protective film. The protective film is formed by a sputtering method using plasma, and the metal wiring is a target when the sputtering method is used. It is used as do.

1A to 1C are cross-sectional views of a device for explaining a method of forming a via hole in a conventional semiconductor device.

2A to 2E are cross-sectional views of devices for explaining a method of forming via holes in a semiconductor device according to the present invention.

Explanation of symbols on the main parts of the drawings

1 and 11: silicon substrate 2 and 12: insulating film

3 and 13: metal wiring 4 and 14: first oxide film

5 and 15: SOG film 6 and 16: Second oxide film

7 and 17: interlayer insulating film 8 and 18: photosensitive film

9 and 19: via hole 20: protective film

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

2A to 2E are cross-sectional views of a device for explaining a method of forming a via hole in a semiconductor device according to the present invention;

2A shows that after forming the metal wiring 13 on the silicon substrate 11 on which the insulating film 12 is formed, the first oxide film 14, the SOG film 15, and the second oxide film 16 are sequentially formed on the entire upper surface thereof. A cross-sectional view of a state in which a metal interlayer insulating film 17 is formed, a photosensitive film 18 is formed on the intermetallic insulating film 17, and then the photosensitive film 18 is patterned.

FIG. 2B illustrates a wet etching of the exposed metal interlayer insulating layer 17 at a predetermined depth by using the patterned Guam film 18 as a mask, followed by dry etching the metal interlayer insulating layer 17 having the remaining thickness. It is sectional drawing of the state which the via hole 19 was formed so that the wiring 13 might be exposed.

FIG. 2C is a cross-sectional view of the protective film 20 formed on the sidewall of the via hole 19 by a sputtering method using plasma. In this case, when the metal wire 13 is used as a target, the metal film 13 has a high energy. A metal, such as aluminum (Al) or tungsten (W), is sputtered by the collision of plasma ions to form a metallic protective film 20 on the sidewalls of the via hole 19. In this case, the plasma is generated using a gas in which argon (Ar) gas, CF ₄ , CHF ₃ and Ar are mixed, or a gas in which C ₂ F ₆ and Ar are mixed.

FIG. 2D is a cross-sectional view of the photoresist layer 18 removed using an oxygen (O ₂ ) plasma, where the loss of the SOG film 15 exposed to the sidewall of the via hole 19 by the protective layer 20 is prevented. do.

FIG. 2E is a cross-sectional view of the photoresist film residue and the protective film 20 completely removed by a cleaning process using a solvent. The sidewall of the via hole 19 is well formed to form a metal layer to be connected to the metal wiring 13. The layer covering of the metal becomes good.

As described above, according to the present invention, since the protective film is formed on the sidewalls of the via holes, the photoresist film is removed, so that the SOG film is prevented from being removed when the photoresist film is removed. Therefore, the layer covering of the metal is improved, thereby improving the electrical characteristics and reliability of the device. In addition, since the shape of the via hole sidewalls can be well maintained without using a separate device, there is an excellent effect that the yield of the device can be improved.

Claims (6)

A method of forming a via hole in a semiconductor device for exposing a predetermined portion of a metal wiring after forming an interlayer insulating film on a silicon substrate on which a metal wiring is formed, Forming a photoresist film on the interlayer insulating film, and then patterning the photoresist film; Forming a via hole to expose the metal wiring by etching the interlayer insulating film by an etching process using the photosensitive film patterned from the step as a mask; And forming a protective film on the sidewalls of the via holes from the step, and then sequentially removing the photoresist film and the protective film. The method of claim 1, The protective film is a via hole forming method of a semiconductor device, characterized in that formed by a sputtering method using a plasma. The method of claim 2, When the sputtering method is used, the metal wiring is used as a target. The method of claim 2, Wherein the plasma is generated by any one of Ar gas, CF ₄ , CHF ₃ and Ar mixed gas or C ₂ F ₆ and Ar mixed gas. The method of claim 1, And the photosensitive film is removed by an oxygen plasma. The method of claim 1, The protective film is a method of forming a via hole in a semiconductor device, characterized in that by removing the solvent.