KR960015566B1 - Contact hole forming method - Google Patents

Abstract

depositing an oxide film(1) on a junction layer(3) to insulate the junction layer(3), and depositing a first protective film(2) protecting the oxide film(1) from over-etching; forming a natural oxide film(4) by etching the first protective film(2) and the insulator(1) on top of the junction layer(3) to form a contact or a via hole; forming a second protective film spacer(5') by blanket etching of a second protective film(5); and etching the natural oxide film(4) exposed by forming the second protecting film spacer(5').

Description

Contact hole formation method of semiconductor device with easy removal of natural oxide film

1 is a cross-sectional view of a contact hole cleaning process according to an embodiment of the present invention;

2 is a contact plug formation by selective tungsten deposition after cleaning according to the present invention.

The present invention relates to a method for forming a contact hole of a semiconductor device, which facilitates removal of a native oxide film generated when forming a contact hole or via hole. In general, a plug forming technique using tungsten chemical vapor deposition is widely used to completely fill a contact hole in a semiconductor device. Tungsten chemical vapor deposition can be classified into a blanket tungsten deposition method (blanket-W) and a selective tungsten deposition method (selective-W) according to a deposition apparatus and a deposition method. Selective tungsten deposition is a method of depositing tungsten only in a selected area of a substrate, that is, a contact hole, and has the advantage that the process is simple without the need for a bonding layer and a post-etching process. Because it is very sensitive to the conditions, it is difficult to maintain and control process characteristics such as selective deposition and contact resistance.

However, after the contact hole is formed, there are many natural oxide films and foreign substances at the base of the hole, which prevents selective tungsten deposition. Therefore, in order to achieve uniform and stable selective tungsten deposition, it is necessary to completely remove these native oxide films and foreign substances present in the contact base.

Conventional methods for removing the natural oxide film and foreign matter is a method of pre-cleaning with a buffered oxide etchant (BOE) dip or NF ₃ plasma prior to selective tungsten deposition.

However, in the case of dip (Dip) in BOE of the conventional method is of a contact base by, the plasma during the pre-cleaning following the imperfection problem of penetration and cleaning, due to the NF ₃ plasma by Cami curl solution to the contact hole bottom portion Damage, polymer formation, and silicon consumption at the bottom of the contact hole are generated, and the silicon consumption by NF ₃ plasma is lowered during selective tungsten deposition.

2WF ₆ (g) + 3Si (s) → 2W (s) + 3SiF ₄ (g)

Combined with the silicon consumption by WF ₆ , such as to cause the consumption of the bonding layer of 500 to 1000 Å, followed by problems in the selective tungsten process.

Another conventional method is to preclean using HF vapor to minimize silicon consumption when removing the native oxide film.

However, when pre-cleaning using HF steam, not only a natural oxide film but also an IPO film (BPSG, TEOS), which is an insulating layer, is simultaneously etched, causing many problems.

The present invention has been made in order to solve the above problems is to provide a method for forming a contact hole of a semiconductor device is easy to remove the natural oxide film for implementing a stabilized selective tungsten deposition.

In order to achieve the above object, the present invention provides a method for forming a contact hole of a semiconductor device which can easily remove a natural oxide film generated at a base of a contact hole or a via hole. A first step of depositing an oxide film and a first passivation layer that protects the excessive etching of the oxide layer, a second step of forming a natural oxide film by selectively etching the first passivation layer and the insulating layer on the junction layer in order to form a contact or via hole, A third step of forming a second passivation layer spacer by a blanket etching process after depositing a second passivation layer on the entire structure, and a fourth step of selectively etching the natural oxide layer exposed by the formation of the second passivation layer spacer. Characterized in that.

Hereinafter, the present invention will be described in detail with reference to FIGS. 1 and 2.

FIG. 1 is a contact hole cleaning process according to an embodiment of the present invention, and FIG. 2 is a view showing a state in which tungsten is selectively deposited after cleaning according to the present invention, and FIG. 3 is a bonding layer.

First, before forming the contact hole, a first nitride film is deposited on the oxide film 1 as shown in FIG. 1A to form a first passivation film 2.

Next, the first protective film 2 and the oxide film 1 are selectively etched to form contact holes. At this time, the native oxide film 4 is formed on the exposed silicon substrate at the bottom of the contact hole.

Next, as shown in FIG. 1 (b), the second nitride film is deposited on the entire structure to form the second protective film 5, and then the natural oxide film 4 is formed by the blanket etching process in FIG. And a second passivation layer on the first passivation layer 1 are removed to form a second passivation layer spacer 5 'on the sidewalls of the oxide layer 1 and the first passivation layer 2 so that the natural oxide layer 4 remains. All portions of the oxide film 1 except for the base of the hole are capped by the first passivation layer and the second passivation layer spacer 5 '.

In this state, when the cleaning process is performed using hydrogen fluoride vapor having an etching rate difference between the nitride film forming the protective film and the natural oxide film as shown in FIG. 1 (d), the natural oxide film at the base of the contact hole not protected by the protective film is hydrogen fluoride. Will react with the steam. The scheme is as follows.

HF (g) + SiO ₂ (s) → SiF ₄ (g) + H ₂ O (g)

Therefore, due to the difference in etching rate due to hydrogen fluoride vapor between the protective film and the oxide film, the natural oxide film at the base of the contact hole can be removed without damaging the IPO film, which is an insulating layer, and the silicon consumption generated during cleaning by NF ₃ plasma is suppressed. .

After removal of the natural oxide film as described above, selective deposition of the tungsten plug 6 is as shown in FIG.

In addition, the present invention is not limited to the above embodiment and can be generally used in the manufacturing process of semiconductor devices such as metal contacts through general contact holes and via holes.

According to the present invention made as described above it is possible to remove the natural oxide film and the natural oxide film growth inhibition of the base of the contact hole can obtain the effect of the stabilized selective tungsten deposition.

Claims (3)

In the method of forming a contact hole of a semiconductor device, which is easy to remove the natural oxide film generated at the base of the contact hole or via hole, the over-etching of the oxide film and the oxide film which insulates the junction layer on the junction layer forming a contact is protected. A first step of depositing a first passivation layer, a second step of forming a natural oxide film by sequentially etching the first passivation layer and the insulating layer on the junction layer in order to form a contact or via hole, and depositing a second passivation layer on the entire structure And then, forming a second protective film spacer by a blanket etching process, and removing the natural oxide film by a fourth step of selectively etching the natural oxide film exposed due to the formation of the second protective film spacer. A method for forming a contact hole in a semiconductor device that is easy. The method of claim 1, wherein the first and second passivation layers are nitride layers. The method of claim 1, wherein the selective etching of the exposed natural oxide layer during the etching of the blanket for forming the second passivation layer spacer is performed using hydrogen fluoride vapor. .