JPH06302564A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To reduce a contact leakage generated between a conductive film formed in a contact hole and a silicon substrate. CONSTITUTION:In a manufacturing method for semiconductor devices, on a silicon substrate 1, an insulation film 2 is formed, and on the insulation film 2, a photoresist pattern 3 is formed. Further, using the photoresist pattern 3 as a mask, fluorine 5 is injected into the insulation film 2 under the condition wherein its acceleration energy is 20keV and its dose is 1X10<15>cm<-2>, and it is so injected thereinto that its flying range is present in the insulation film 2. Thereafter, a contact hole is formed by the dry-etching through a fluorine based gas. Subsequently, after the removal of the photoresist pattern 3, a conductive film 4 is formed on the insulation film 2, and a heat treatment is so performed that the conductive film 4 is made into an alloy. Since by virtue of the introduction of fluorine 5 alloy spikes can be suppressed from being formed between the silicon substrate and the conductive film 4, the contact leakage generated between them can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a contact leak that occurs when a contact hole is formed for contact between a silicon substrate and a conductive film formed on the silicon substrate. The present invention relates to a method for manufacturing a semiconductor device that can reduce

[0002]

2. Description of the Related Art A conventional method of manufacturing a semiconductor device will be described below.

FIG. 2 is a schematic sectional view showing each manufacturing step of a conventional semiconductor device manufacturing method. In FIG. 2, 1 is a silicon substrate, 2 is an insulating film formed on the silicon substrate 1, and 3 is an insulating film. Photoresist patterns 4 formed on the insulating film 2 are conductive films formed after forming contact holes in the insulating film 2.

First, as shown in FIG. 2A, after forming an insulating film 2 on a silicon substrate 1, a photoresist is applied on the insulating film 2 in a continuous process of forming an insulating film. Then, the photoresist is patterned to form a photoresist pattern 3 on the insulating film 2.

Next, as shown in FIG. 2B, the insulating film 2
On the other hand, a contact hole is formed in the insulating film 2 by performing dry etching using a fluorine-based reaction gas with the photoresist pattern 3 as a mask.

Next, as shown in FIG. 2C, after removing the photoresist pattern 3, a conductive film 4 is formed on the insulating film 2 by a sputtering method. After that, the conductive film 4
The conductive film 4 is alloyed by performing heat treatment on.

[0007]

However, in the above configuration, when the contact hole is formed in the insulating film 2 by dry etching, the etching residue caused by the variation in the film thickness of the insulating film 2 is removed. Therefore, it is necessary to extend the overetching time. The damage caused by the overetching for a long time promotes the formation of alloy spikes between the conductive film 4 and the silicon substrate 1, resulting in a problem that contact leak increases.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a method of manufacturing a semiconductor device capable of reducing a contact leak between a conductive film and a silicon substrate in a contact hole. .

[0009]

In order to achieve the above object, the present invention uses a fluorine-based gas for the insulating film by previously injecting fluorine into a portion of the insulating film where a contact hole is formed. It promotes dry etching.

Specifically, the solution means taken by the present invention is to form an insulating film on a silicon substrate, to form a photoresist pattern on the insulating film, and to form the photoresist pattern on the insulating film. A step of injecting fluorine as a mask under the condition that a range exists in the insulating film,
A step of forming a contact hole in the insulating film by performing dry etching using a fluorine-based gas on the insulating film using the photoresist pattern as a mask; and after removing the photoresist pattern, conducting on the insulating film. This is a configuration including a step of forming a conductive film and a step of heat-treating the conductive film to alloy the conductive film.

[0011]

With the above structure, since the portion of the insulating film where the contact hole is formed is previously filled with fluorine, the etching rate when the contact hole is formed in the insulating film by dry etching using a fluorine-based gas is improved. Since it is improved, the over-etching time required to remove the etching residue can be shortened. Therefore, the roughness caused on the surface of the silicon substrate due to overetching is
This is reduced as compared with the conventional semiconductor device manufacturing method.

Of the fluorine injected into the insulating film, the fluorine that reaches the silicon substrate is piled up at the interface between the silicon substrate and the conductive film by heat treatment after the conductive film is formed, and the interface is electrically inactivated. To do.

Therefore, according to this embodiment, damage to the silicon substrate due to dry etching when forming the contact hole can be reduced, and formation of alloy spikes between the conductive film and the silicon substrate due to the damage can be suppressed. Therefore, contact leak can be reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view showing each manufacturing step of a method of manufacturing a semiconductor device according to an embodiment of the present invention.

In the figure, 1 is a silicon substrate, 2 is an insulating film formed on the silicon substrate 1, 3 is a photoresist pattern formed on the insulating film 2, and 4 is a contact hole formed in the insulating film. The formed conductive film 5 is fluorine injected into the insulating film 2 using the photoresist pattern 3 as a mask.

First, as shown in FIG. 1A, after an insulating film 2 having a thickness of 100 nm is formed on a semiconductor silicon substrate 1, a photoresist is formed on the insulating film 2 continuously in the insulating film forming step. Apply. Then, this photoresist is patterned to form a photoresist pattern 3.

Then, the photoresist pattern 3 is formed.
Is used as a mask, and fluorine 5 is implanted under the conditions of an acceleration energy of 10 to 40 keV and a dose amount of 1 × 10 ¹⁵ cm ⁻² using an ion implantation device. Since the range of fluorine 5 with this acceleration energy is 16 to 67 nm, a range exists in the insulating film 2. In this case, by setting the acceleration energy to 10 keV or more, it is possible to introduce the effect of fluorine implantation into the lower portion of the insulating film 2 without the implanted fluorine 5 being concentrated near the surface of the insulating film 2. Also, the acceleration energy is 4
By setting it to 0 keV or less, damage to the semiconductor silicon substrate 1 due to fluorine implantation can be suppressed.

Next, as shown in FIG. 1B, the insulating film 2
By using the photoresist pattern 3 as a mask and performing dry etching using a fluorine-based gas, the insulating film 2
A 2 μm square contact hole is formed in the substrate.

Next, as shown in FIG. 1 (c), after removing the photoresist pattern 3, the insulating film 2 has a thickness of 100 nm formed by sputtering and is made of aluminum (hereinafter abbreviated as Al). ) / Silicon (hereinafter abbreviated as Si), Al / Si / copper (hereinafter abbreviated as Cu), tungsten (hereinafter abbreviated as W), and Cu conductive film 4 for wiring. To form.

Then, in a hydrogen atmosphere, 350-
By conducting a heat treatment for 30 minutes at a temperature of 450 ° C., the conductive film 4 is alloyed.

Fluorine 5 used in this embodiment was used.
The acceleration energy and the dose amount of the
It is determined by 0 nm, and the acceleration energy and dose amount of fluorine 5 change depending on the film thickness of the insulating film 2.

The operation of the method of manufacturing the semiconductor device of this embodiment having the above structure will be described below.

In dry etching of the insulating film 2 using a fluorine-based gas, fluorine-based ions are incident on the surface of the insulating film 2 to form Si-F bonds, and the Si-F bonds are converted to volatile SiF ₄ . It progresses by becoming. Therefore,
By injecting fluorine 5 into the etched portion of the insulating film 2 before dry etching with fluorine gas for forming the contact hole, a Si—F bond is formed in the portion of the insulating film 2 into which the fluorine 5 is injected. Therefore, the etching rate of the portion into which the fluorine 5 is injected increases.

When the above conditions are adopted as the conditions for implanting the fluorine 5, the etching rate of the insulating film 2 is doubled as compared with the conventional one, so that the overetching time required to remove the etching residue is increased. It can be shortened. Therefore, the roughness caused on the surface of the silicon substrate 1 due to overetching can be reduced as compared with the conventional semiconductor device manufacturing method.

In the above embodiment, the acceleration energy of the fluorine 5 is set under the condition that the range is in the insulating film 2, but some fluorine 5 reaches the silicon substrate 1.
However, the fluorine 5 reaching the silicon substrate 1 is
By heat treatment after forming the conductive film 4, the interface between the silicon substrate 1 and the conductive film 4 is piled up to electrically inactivate the interface.

Therefore, according to this embodiment, it is possible to reduce the damage of dry etching when forming the contact hole and to suppress the formation of alloy spikes between the conductive film 4 and the silicon substrate 1 due to the damage. Therefore, contact leak can be reduced.

[0028]

As described above, according to the method of manufacturing a semiconductor device of the present invention, the portion of the insulating film to be etched before the dry etching step using the fluorine-based gas for forming the contact hole. Since fluorine is injected into the substrate, the etching rate during the dry etching process using a fluorine-based gas is improved, so the overetching time required to remove the etching residue can be shortened. Roughness caused on the surface of the silicon substrate due to is reduced as compared with the conventional semiconductor device manufacturing method.

Therefore, according to the present invention, it is possible to realize an excellent method for manufacturing a semiconductor device capable of reducing the contact leak between the silicon substrate and the conductive film formed on the silicon substrate.

[Brief description of drawings]

1A, 1B, and 1C are schematic sectional views showing respective manufacturing steps of a method for manufacturing a semiconductor device according to an embodiment of the present invention.

2A, 2B, and 2C are schematic cross-sectional views showing respective manufacturing steps of a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

 1 Silicon substrate 2 Insulating film 3 Photoresist pattern 4 Conductive film 5 Fluorine

Claims (1)

[Claims] 1. A step of forming an insulating film on a silicon substrate, a step of forming a photoresist pattern on the insulating film, and a step in the insulating film using the photoresist pattern as a mask. A step of injecting fluorine under existing conditions; a step of forming a contact hole in the insulating film by performing dry etching using a fluorine-based gas on the insulating film using the photoresist pattern as a mask; A semiconductor device comprising: a step of forming a conductive film on the insulating film after removing the pattern; and a step of alloying the conductive film by heat-treating the conductive film. Production method.