JPH0737834A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide the improvement of a method of removing defective layers generated on the bottom of a contact hole in a dry etching process at the time of the formation of the contact hole. CONSTITUTION:A method of manufacturing a semiconductor device consists of a constitution having a process, wherein an insulating film 12 is formed on a silicon substrate 11, a prescribed resist pattern 13 is formed, the film 12 is subjected to dry etching using the pattern 13 as a mask and an opening 15 is formed to expose the substrate 11, a process, wherein defect layers 14 generated in the surface of the substrate 11 at the time of the dry etching process are oxidized to form a selective oxide layer 14A, and a process for removing the layer 14A by wet etching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more specifically, an object of the invention is to improve a method of removing a defective layer at the bottom of a contact hole in dry etching when forming a contact hole.

[0002]

2. Description of the Related Art A conventional method of manufacturing a semiconductor device will be described below with reference to FIGS. The semiconductor device manufacturing method according to the conventional example is a method of forming a contact hole for making a contact between a wiring and a substrate. First, on the silicon substrate (1), BPSG [Boro-Pho
spo Silicate Glass] film (2) is formed, and a photoresist is applied on the upper surface of the film to form a resist film, which is exposed through a mask having a desired pattern and then developed to form a resist pattern (3) To form RIE (Reac
By using the resist pattern (3) as a mask, BPS is performed by reactive ion etching.
The G film (2) is dry-etched to form openings (5) to expose the silicon substrate (1) (FIG. 1).

At this time, an opening (5) is formed during etching.
On the surface of the silicon substrate (1) exposed from the above, a defect layer (4) generated by collision of ions used for etching occurs. This causes contact failure and other problems and must be removed. Therefore, CF ₄
The defect layer (4) was lightly dry-etched and removed using + O ₂ gas to form a contact hole.

[0004]

However, according to the above-mentioned conventional method, during the dry etching for removing the defect layer (4), the accurate thickness of the defect layer (4) (about 20) is obtained.
It is estimated to be 0 to 300Å), but it is slightly overetched because it is not possible to confirm. For this reason, the silicon substrate (1) is over-etched and the contact hole is formed deeper than necessary. Therefore, as miniaturization progresses, the resistance value of the wiring formed in the contact hole increases. As a result, there arise problems such as variations in product characteristics.

Further, since dry etching is performed to remove the defect layer (4), new defects are generated due to ion collision of the dry etching, and there is a problem that the defects are not completely removed.

[0006]

The present invention has been made in view of the above-mentioned conventional drawbacks, and as shown in FIGS. 1 to 5, an insulating film (12) is formed on a silicon substrate (11), A predetermined resist pattern (13) is formed to form the insulating film (1
2) is dry-etched to form an opening (15) to expose the silicon substrate (11); and a defect layer () formed on the surface of the silicon substrate (11) during the dry-etching step. A step of selectively oxidizing the selective oxidation layer (14A) to form a selective oxidation layer (14A);
By providing the step of removing A) by wet etching, it is possible to provide a method for manufacturing a semiconductor device in which over-etching at the time of removing a defect layer can be suppressed as much as possible and defects can be completely removed. is there.

[0007]

[Operation] According to the method for manufacturing a semiconductor device of the present invention, as shown in FIGS. 1 to 4, an insulating film (12) is formed on a silicon substrate (11) and a predetermined resist pattern (13) is formed. Then, the insulating film (12) is dry-etched to form an opening (15) to expose the silicon substrate (11), and then the defect layer (14) generated on the surface of the silicon substrate (11) is oxidized. is doing.

In this oxidation step, there is a difference in oxidation rate of about one digit between the defect layer (14) generated on the silicon substrate by ion collision and the defect-free silicon substrate (11). Since (14) is oxidized at a rate of about 10 times that of the defect-free silicon substrate (11), even if the defect layer (14) is completely oxidized to become the selective oxidation layer (14A), The substrate (11) is hardly oxidized, and as a result, only the defect layer (14) is selectively oxidized.

After that, a selective oxidation layer (14) which was once a defect layer (14) was formed by using a hydrofluoric acid-based etching solution.
A) is removed by wet etching. At this time, since the silicon substrate (11) having no defect is hardly oxidized, it is hardly removed by etching.
Thereby, almost only the defect layer (14) is selectively selected,
In addition, it is possible to remove the defect layer without excess or deficiency, and it is possible to remove the defect layer without overetching as in the conventional case. Furthermore, at this time, since the etching is performed by wet etching, it is possible to prevent a new defect from occurring when removing the defect layer.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a semiconductor device according to an embodiment of the present invention will be described below with reference to the drawings. 1 to 4 are
FIG. 6 is a cross-sectional view showing the method of manufacturing the semiconductor device according to the example of the invention. First, a BPSG film (12) is formed on a silicon substrate (11), a photoresist is applied on the upper surface of the BPSG film (12) to form a resist film, which is exposed through a mask having a desired pattern and then developed. Forming a resist pattern (13), using the resist pattern (13) as a mask, Ar gas with a flow rate of 1000 SCCM, and a flow rate of 60 SCCM
RI under the conditions of pressure 1.8 Torr and RF power 650 W using CHF ₃ gas of CF and CF ₄ gas of flow rate 60 SCCM
The E is used to etch the BPSG film (12) to form openings (15) (FIG. 1).

At this time, a defect layer (14) is formed on the surface of the silicon substrate (11) exposed at the bottom of the opening (15) due to ion collision during dry etching. next,
The resist pattern (13) is removed using plasma ashing and sulfuric acid (FIG. 2), and the defect-free silicon substrate (11) is thermally oxidized for about 30 minutes at a temperature of 800 ° C., that is, about 20 to 30 Å. (Figure 3).

Then, a defect-free silicon substrate (11)
And the defect layer (14) has an oxidation rate ratio of 1
Since it is about 0: 1, the defect layer (1
4) is oxidized to about 200 to 300Å, most of the defect layer (14) is oxidized, the selective oxidation layer (14A) is formed, and the silicon substrate (11) in the defect-free portion is hardly oxidized.

After that, wet etching is performed for about 5 minutes using 200: 1 hydrofluoric acid to etch and remove the selective oxidation layer (14A) (FIG. 4). As a result, the selective oxidation layer (14A), that is, the defect layer (14) is removed, and the defect-free silicon substrate (11) is hardly removed. As a result, the defect layer (14) is selectively removed. .

Therefore, it is possible to remove the defect layer (14) without excess or deficiency, and it is possible to remove the defect layer (14) without overetching as in the conventional case.
Furthermore, because it is etched by wet etching,
It is also possible to prevent a new defect from occurring when removing the defect layer (14).

[0015]

As described above, according to the method of manufacturing a semiconductor device of the present invention, the insulating film (12) is formed on the silicon substrate (11) and the predetermined resist pattern (1) is formed.
3) is formed and the insulating film (12) is dry-etched,
An opening (15) is formed to expose the silicon substrate (11), and the silicon substrate (1
1) The defect layer (14) generated on the surface is oxidized to form a selective oxidation layer (14A), and the selective oxidation layer (14A) is removed by wet etching.

Therefore, it becomes possible to remove the defect layer (14) without excess or deficiency, and it becomes possible to remove the defect layer without overetching as in the conventional case, and etching is performed by wet etching. Therefore, it is possible to prevent a new defect from occurring when removing the defect layer.

[Brief description of drawings]

FIG. 1 is a first cross-sectional view illustrating a method of manufacturing a semiconductor device according to an embodiment of the invention.

FIG. 2 is a second cross-sectional view illustrating the method for manufacturing the semiconductor device according to the embodiment of the invention.

FIG. 3 is a third cross-sectional view illustrating the method for manufacturing the semiconductor device according to the embodiment of the invention.

FIG. 4 is a fourth sectional view illustrating the method for manufacturing the semiconductor device according to the embodiment of the invention.

FIG. 5 is a first cross-sectional view illustrating the method of manufacturing the semiconductor device according to the conventional example.

FIG. 6 is a second cross-sectional view illustrating the method for manufacturing the semiconductor device according to the conventional example.

FIG. 7 is a third cross-sectional view explaining the method for manufacturing the semiconductor device according to the conventional example.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01L 21/306

Claims (2)

[Claims] 1. An insulating film (1) is formed on a silicon substrate (11).
2) is formed, a predetermined resist pattern (13) is formed, the insulating film (12) is dry-etched using the resist pattern (13) as a mask, and an opening (15) is formed to form the silicon substrate. Exposing (11); forming a selective oxidation layer (14A) by oxidizing the defect layer (14) generated on the surface of the silicon substrate (11) during the dry etching step; And a step of removing the oxide layer (14A) by wet etching. 2. An insulating film (12) made of a BPSG film is formed on a silicon substrate (11), a predetermined resist pattern (13) is formed, and the insulating film (13) is used as a mask. 12) dry etching
In the step of forming the opening (15) to expose the silicon substrate (11) and the step of the dry etching, the defect layer (14) generated on the surface of the silicon substrate (11) is oxidized and selected. A method of manufacturing a semiconductor device, comprising: a step of forming an oxide layer (14A); and a step of removing the selective oxidation layer (14A) by wet etching using a hydrofluoric acid-based etching solution.