JPH05109647A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a semiconductor device which can prevent an abnormal growth of a metal into a semiconductor substrate at the time of selective growth of the metal into an inside of a contact hole, enables coherency at a contact part, and prevents the substrate surface of a contact bottom part from being etched and hence from being damaged. CONSTITUTION:When forming a contact of a semiconductor device, a polycrystalline silicon thin film 1 is formed after forming a contact hole, a flattening film 6 is formed on it, and then its double-layer film is etched back in sequence, thus enabling a polycrystalline silicon 1a to remain only within the contact. After that, a first metal 7 is selectively deposited on the polycrystalline silicon, thus preventing an abnormal growth of a metal into a semiconductor substrate at the time of selective growth of the metal, enabling coherency of the metal to be improved, and preventing the substrate surface of a contact bottom part from being etched and damaged since the inside of the contact is coated with the polycrystalline silicon film.

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 particularly to a method of forming a contact portion.

[0002]

2. Description of the Related Art A conventional semiconductor device manufacturing method is shown in FIG.
As shown in (a), the device isolation region 3 is formed on the semiconductor substrate 5.
Then, the impurity diffusion layer 4 is formed by ion implantation or a thermal diffusion method. Next, the insulating film 2 such as an oxide film is formed on the surface of the substrate by, for example, the CVD method, and then the contact portion is formed by the photolithography technique and the etching technique. Next, as shown in FIG. 2B, the photoresist is removed, and then the first metal 7 is selectively grown on the contact portion. Then, the wiring of the second metal 8 is deposited by the sputtering method, and the photolithography is performed. , It is formed by using an etching technique. In the case of tungsten growth, for example, in the case of tungsten growth, the above-mentioned selective growth technique of metal deposits tungsten at a temperature of 200 to 300 ° C. by using WF ₆ + H ₂ gas under reduced pressure. According to this method, tungsten starts to grow only on the silicon surface of the contact portion, and then tungsten is deposited on the tungsten so as to fill the contact hole.

[0003]

In this conventional method for manufacturing a semiconductor device, during the selective growth of metal (here, the growth of tungsten will be described), the tungsten that first grows at the bottom of the contact is the same as the Si of the semiconductor substrate 5. The reaction gas causes a reaction of 2WF ₆ + 3Si → W + 3SiF ₄ ,
Grow while etching the substrate. Especially semiconductor substrate 7
The gas rapidly invades into the interface between the insulating film 2 and the insulating film 2, and unwanted lateral growth 10 of tungsten occurs. The growth of W in the lateral direction of the interface between the semiconductor substrate and the insulating film is usually 1000 to 3000 angstroms (see FIG. 2).
(B) When the tungsten 10 grows out of the impurity diffusion layer 4, the impurity diffusion layer and the substrate are short-circuited.
Therefore, the distance d between the contact and the impurity diffusion layer (see FIG.
In the case of (b), the mask overlay accuracy of photolithography and the lateral growth distance of tungsten are required in advance, which is a problem to prevent miniaturization of the semiconductor device. Furthermore, the tungsten grown as described above has poor adhesion to an insulating film such as an oxide film,
There is a problem that it is not preferable in terms of reliability.

In order to solve the above problem, as shown in FIG. 3, a polycrystalline silicon film is deposited on the surface of the substrate 5 after the contact holes are formed, and then the polycrystalline silicon is anisotropically etched to form a contact. The polycrystalline silicon 12 is left only on the side wall of the hole, and then selective growth of tungsten is performed.
Subsequently, a method of forming a second metal wiring has been proposed.

According to this method, undesired growth of tungsten at the interface between the first insulating film 2 and the semiconductor substrate 5 can be prevented, and the adhesion of tungsten can be improved. However, in this case, the anisotropic etching of polycrystalline silicon etches the semiconductor substrate at the bottom of the contact, and the damaged layer 11 remains on the substrate due to the collision of plasma ions, which causes leakage. There is.

An object of the present invention is to prevent abnormal growth of metal in a semiconductor substrate during selective growth of metal, improve adhesion at the contact portion, and damage the substrate surface at the bottom of the contact without etching. An object of the present invention is to provide a method for manufacturing a semiconductor device without a problem.

[0007]

According to a method of manufacturing a semiconductor device of the present invention, after forming a contact hole, a step of forming a thin polycrystalline silicon film, a step of forming a planarizing film,
The step of etching back the flattening film to remove the flattening film other than the contact hole portion, the step of etching back the polycrystalline silicon film to remove the polycrystalline silicon film other than the contact hole portion, and the inside of the contact hole And the step of selectively depositing the first metal on the polycrystalline silicon remaining inside the contact hole.

[0008]

The present invention will be described below with reference to the drawings. FIG. 1 is a process sectional view of an embodiment of the present invention.

First, as shown in FIG. 1 (a), an oxide film 3 for element isolation is formed on a semiconductor substrate 5, and then an impurity having a conductivity type opposite to that of the substrate is introduced by an ion implantation method.
Heat treatment is performed to form the impurity diffusion layer 4. (Formation of the gate electrode, etc. is omitted in the middle) Next, for example, CV is formed on the semiconductor substrate.
An oxide film 2 is deposited by the D method, and contact holes are formed by the photolithography technique / etching technique. Next, polycrystalline silicon is deposited on the surface of the semiconductor substrate by, for example, a low pressure CVD method to a thickness of about 100 to 300 angstroms.
After that, a film having good flatness, for example, in this case, a photoresist 6 is spin-coated to a thickness of 2 to 3 μm, and then 15
Bake at 0 to 190 ° C.

Next, as shown in FIG. 1C, a photoresist is applied to, for example, O ₂ + 10% CF ₄ , 200 W, 1 to.
Anisotropic etching is performed under the condition of rr so that the resist 6a remains only in the contact portion.

Next, polycrystalline silicon is used, for example, CF ₄ +.
Isotropic etching is performed for 10 seconds under the conditions of 20% O ₂ , 200 W and 0.4 torr to remove the polycrystalline silicon except the contact portion.

Next, the resist is removed by O ₂ plasma as shown in FIG.
A first metal, for example, tungsten 7 in this case is selectively grown on a and the contact hole is filled. At this time, the tungsten growth conditions are a pressure of 1 torr and a temperature of 250 ° C.
Then, WF ₆ + H ₂ gas is used. The deposition rate is Angstrom / min.

Next, as shown in FIG. 1E, a second metal is deposited by the sputtering method, and a wiring pattern is formed by the photolithography technique / etching technique.

According to the above method, since there is polycrystalline silicon at the bottom and side walls of the contact hole during selective growth of tungsten, it is possible to suppress abnormal growth of tungsten at the interface between the Si substrate and the insulating film, and It is also possible to prevent damage to the diffusion layer.

The above embodiment is one embodiment of the present invention.
For example, silicate glass or the like may be used for the flattening film instead of the photoresist.

[0016]

As described above, according to the present invention, after forming a contact hole, a step of forming a thin polycrystalline silicon film, a step of forming a flattening film, and a step of etching back the flattening film. And then removing the polycrystalline film on the planarization film and the insulating film by etching the polycrystalline silicon film to leave the polycrystalline silicon inside the contact hole and the first step on the polycrystalline silicon remaining inside the contact hole. (1) Since it is possible to suppress the lateral spread of tungsten from the contact opening to the outside, the overlapping margin of the contact and the impurity diffusion layer can be increased. The size of the semiconductor device can be reduced, and the semiconductor device can be miniaturized. (2) With the polycrystalline silicon on the side wall of the contact hole, the first
The adhesion of the metal is improved and the reliability can be improved. (3) Since the substrate surface at the bottom of the contact is not etched, damage to the substrate can be prevented. And so on.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a conductor element shown in the order of steps for explaining an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a semiconductor element shown in the order of steps for explaining an example of a conventional method for manufacturing a semiconductor device.

FIG. 3 is a cross-sectional view of a semiconductor element shown in the order of steps for explaining another example of the conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

 1 Polycrystalline Silicon 2 First Insulating Film 3 Element Isolation Oxide Film 4 Impurity Diffusion Layer 5 Semiconductor Substrate 6 Flattening Film 6a Flattening Film in Contact Hole 7 First Metal 8 Second Metal 9 Photoresist 10 In Semiconductor Substrate Growth region of metal on semiconductor substrate 11 Etched portion and damaged region of semiconductor substrate 12 Polycrystalline silicon

Claims (1)

[Claims] 1. A step of forming an impurity diffusion layer on a semiconductor substrate, a step of forming a first insulating film on the surface of the semiconductor substrate, and the impurity diffusion layer on a part of the first insulating film. In a method of manufacturing a semiconductor device, which comprises a step of forming a contact hole for enabling electrical connection from the outside, and a step of burying the contact hole by selective growth of metal, a thin polycrystalline film after the contact hole is formed. Forming a silicon film, forming a flattening film on the polycrystalline silicon film, etching back the flattening film, and removing the flattening film other than the contact hole portion; A step of etching the silicon to remove the polycrystalline silicon film other than the contact hole portion, a step of removing the flattening film in the contact hole, and a first step in the contact hole where the polycrystalline silicon film remains And a step of selectively depositing the metal described in (4) above.