JPH043923A - Manufacturing method of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a semiconductor device, in which no etching residue is left behind by the irregularities of a foundation insulating film, by a method wherein a contact hole is bored, a tungsten film is deposited on the whole surface of a substrate, a section except the inside of the contact hole is removed, and aluminum or an aluminum alloy film is taken out. CONSTITUTION:A BPSG film as an insulating film 2 is deposited on a silicon substrate 1, and an aluminum alloy 3 is deposited on the BPSG film. A contact hole 5 is bored through dry etching by using a photo-resist 4, and tapered, and the photo-resist 4 is removed. Titanium 6 is deposited on the whole surface through dip-etching, and a titanium nitride 7 is deposited. Tungsten 3 is deposited on the whole surface, and tungsten is left only in the contact hole 5, but the contact hole 5 is over-etched until height reaches the same height as the insulating film 2, the aluminum alloy 3 is taken out, and desired metallic wiring is executed. Accordingly, a semiconductor device, in which the irregularities of the surface of tungsten are not transferred to a foundation insulating film and the etching residue of tungsten is also removed simultaneously, is acquired.

Description

[Detailed description of the invention] Industrial application field of the present invention Ct Regarding a method for manufacturing a semiconductor device To the process of opening a contact hole on an insulating film and forming a metal wiring
This provides an improved method.

Conventional technology In the conventional method for manufacturing semiconductor devices, a contact hole is formed on an insulating film, tungsten is formed on the entire surface, and then the entire surface is etched back to remove tungsten other than the contact hole, thereby forming tungsten only in the contact hole. Although it is known that stable contact characteristics can be obtained by performing metal wiring after formation, such a method is effective, for example.
VMIC Conference p 129-1351
989. However, this method has the problem that when tungsten is etched back, the unevenness on the tungsten surface is simply transferred onto the underlying insulating film, making it difficult to perform subsequent photolithography. A method of forming silicon nitride as a sacrificial film in a detailed manner is described in the above-mentioned literature. In addition, as means 2, there is a method of multi-layering barrier metal with aluminum alloy.
EE VMIC Conference p357-36
However, method 1 has the problem of increasing the stress generated by silicon nitride and the process of removing silicon nitride. Atsushi has the problem of poor alloy coverage, which causes voids in the contact hole area when depositing tungsten, but also has the problem that when etching back tungsten, the etching rate largely depends on the surface area of the tungsten. Although there is a problem in that it is difficult to detect the end point when etching back tungsten, there is also a problem in that when etching back tungsten, etching remains due to unevenness in the underlying insulating film. It is an object of the present invention to provide a method for manufacturing a semiconductor device in which surface irregularities are not directly transferred to an underlying insulating film and etching residues are not generated due to irregularities in the underlying insulating film.

Means for Solving the Problems Present Invention (1) 11 After opening a contact hole that penetrates an insulating film and an aluminum or aluminum alloy film formed on a substrate and depositing a tungsten film on the entire surface of the substrate,
This method of manufacturing a semiconductor device is characterized in that it includes a step of removing the tungsten film except inside the contact hole using a dry etching method, and then removing the aluminum or aluminum alloy film.

In addition, the present invention (2) f; L After opening a contact hole on the insulating film formed on the substrate using a photoresist as a mask, depositing a tungsten film on the entire surface of the substrate with the photoresist remaining, and then forming the contact hole. This method of manufacturing a semiconductor device is characterized by including a step of removing a tungsten film other than the inside, and then removing a photoresist.

According to the above structure (1), the present invention forms an aluminum or aluminum alloy film on the insulating film, thereby preventing the unevenness of the tungsten surface from being transferred directly to the underlying insulating film. Furthermore, by using an aluminum alloy, it is easy to remove etching residue.

In addition, with configuration (2) above, after opening the contact characteristics, the tungsten film is deposited over the entire surface of the substrate with the photoresist remaining, thereby shortening the process and transferring the unevenness of the tungsten surface directly to the underlying insulating film. Therefore, no etching residue is generated due to unevenness of the underlying insulating film.

Example (Example 1) An example will be described in detail below with reference to the drawings. FIG. 1 is a schematic manufacturing process diagram of a method for manufacturing a semiconductor device in Embodiment 1 of the present invention. For example, a BPSG film is deposited to a thickness of 800 nm as an insulating film 2 on a substrate 1 by the CVD method, and an aluminum alloy 3 is deposited to a thickness of 50 nm on it. It is also possible to taper the contact hole 5 by about 5 degrees.
After that, the photoresist 4 is removed.

In the same figure (B), after deep etching using a mixed solution of hydrofluoric acid (HF) and ammonium fluoride (NH4F), a barrier metal such as titanium 6
After that, tungsten hexafluoride (WF6) and hydrogen (
Tungsten 8 is deposited on the entire surface by cX and CVD using a mixed gas containing H2) and silane (S i H4). At this time, the deposition conditions for tungsten 8 are used so that voids of tungsten 8 do not occur in the contact hole 5 as much as possible.
By etching the entire surface using F6), tungsten other than the contact hole 5 is removed, leaving tungsten only in the contact hole 5. At this time, aluminum alloy 3 was used as an etching stopper.1. X.

Overetching is performed until the height of the tungsten 8 left in the contact hole 5 becomes the same height as the insulating film 2.

In the same figure (D), aluminum alloy 3 is then heated using hot phosphoric acid.
After removing, desired metal wiring is performed.

As explained above, by using the aluminum alloy 3 in this example, the surface irregularities of the tungsten 8 are not transferred to the base insulating film 2, and the subsequent removal of the aluminum alloy 3 is easy. There is a possibility that this may occur due to the unevenness of film 2.Aluminum alloy 3
There is no aluminum alloy with poor coverage in the contact hole 5, and no voids are generated in the tungsten 8.
The tungsten 8 formed only in the contact hole 5 in this way facilitates the subsequent metal wiring step 9 and provides good contact characteristics with high reliability. HF) and ammonium fluoride (NH4F). Other etching solutions may be used, and carbon tetrafluoride (CF4) or sulfur hexafluoride (S
A similar effect to L can be obtained by dry etching using F6) or the like. Force using a silicon substrate as the substrate (
Other semiconductor substrates may be used, or other insulating films may be used, such as a BPSG film as the insulating film (~ Also, as a barrier metal, a double layer film of titanium and titanium nitride, titanium tungsten, or a high melting point metal) may be used. A similar effect can be obtained by using silicide, etc., or it is not necessary to use a barrier metal.Also, when depositing tungsten, a mixed gas containing tungsten hexafluoride, hydrogen, and silane is used as a reactive gas. strength using metal fluoride and hydrogen silane, dichlorosilane,
Any mixed gas containing at least one of trichlorosilane is sufficient, and other high melting point metals may be used in place of tungsten. Similar effects can be obtained by using other reactive gases such as chlorine compounds (Example 2
) FIG. 2 is a schematic manufacturing process diagram of a method for manufacturing a semiconductor device in Example 2 of the present invention. In this example, a method may be used in which a tungsten film is deposited over the entire surface of the substrate with the photoresist remaining. The following explanation will be given sequentially along the same figures (A) to (C).
deposited to a thickness of 0 nm using photoresist 4, e.g.
．． A 7 μm square contact hole 5 is opened by dry etching.It is preferable to taper the contact hole 5 by about 5 degrees.
After deep etching using the mixed solution of F), as a barrier metal, for example, titanium 6 is deposited on the entire surface by a 5 nm sputtering method, and titanium nitride 7 is deposited by a 1100 nm sputtering method. ) and hydrogen (H2) and silane (SiH4)
Using a mixed gas containing 1. X, tungsten 8 is deposited on the entire surface by the CVD method. SF6)
By etching the entire surface using
Leave tungsten only in. Kono Taku Photoresist 4
Using t,L as an etching stopper, over-etch until the height of the tungsten 8 left in the contact hole 5 is the same as that of the insulating film 2. After that, after removing the photoresist 4, as shown in FIG. 1(D). Perform the desired metal wiring as shown.

As explained above, in this example, the number of steps is reduced by depositing a tungsten film over the entire surface of the substrate with the photoresist remaining, and by using the photoresist 4, the surface irregularities of the tungsten 8 are smoothed. There is no transfer to the base insulating film 2, and the subsequent removal of the photoresist 4 is easy.However, there is also no etching residue during etching back of the tungsten 8, which may occur due to the unevenness of the base insulating film 2. The tungsten 8 formed only in the contact hole 5 in this way facilitates the subsequent metal wiring 9 and provides good contact characteristics with high reliability.

In this example, a silicon substrate was used as the substrate, but other semiconductor substrates may be used, and BPS was used as the insulating film.
Strength using G film Other insulating films may also be used. Further, similar effects can be obtained by using a double layer film of titanium and titanium nitride, titanium tungsten, or silicide of a high melting point metal as the barrier metal. Alternatively, it is not necessary to use a barrier metal.Also, when depositing tungsten, a mixed gas containing tungsten hexafluoride, hydrogen and silane (metal heptadide, hydrogen silane, Any mixed gas containing at least one of dichlorosilane and trichlorosilane is sufficient, and other high melting point metals may also be used instead of tungsten.
Although the same effect can be obtained by using other reactive gases such as chlorine compounds, in the present invention (1), as described in detail of the invention, the entire surface is etched back. By forming an aluminum alloy, the surface unevenness of the tungsten is not transferred to the underlying insulating film, and the aluminum alloy can be easily removed afterwards. The etching residue during etching is also removed at the same time.Furthermore, there is no aluminum alloy with poor coverage in the contact hole, and no voids are generated in the tungsten (- Furthermore, the present invention (
2) By depositing a tungsten film over the entire surface of the substrate while leaving the photoresist, the number of steps can be reduced.
By using a photoresist, the surface irregularities of tungsten are not transferred to the underlying insulating film, and the photoresist can be easily removed afterwards. However, the etching residue that may occur due to the unevenness of the underlying insulating film during etching of tungsten is also removed at the same time. In this way, the tungsten formed only in the contact hole facilitates subsequent metal wiring and provides good, reliable contact characteristics.
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[Brief explanation of drawings]

FIG. 1 is a schematic process sectional view of a method for manufacturing a semiconductor device according to an embodiment of the present invention. FIG. 2 is a schematic process sectional view of a method for manufacturing a semiconductor device according to yet another embodiment of the invention.・Silicon substrate, 2... Insulation WL 3... Aluminum alloy ff14-... Photoresist, 5... Contact hole, 6... Titanium, 7... Titanium nitride, 8... Tungsten, 9...Name of metal power distribution agent Patent attorney Shigetaka Awano and 1 other person Fig.

Claims (4)

[Claims] (1) A step of forming an insulating film and an aluminum or aluminum alloy film on the substrate, a step of opening a contact hole penetrating the insulating film and the aluminum or aluminum alloy film, and depositing a tungsten film on the entire surface of the substrate. a step of removing the tungsten film other than the inside of the contact hole by dry etching using a fluorine compound or a chlorine compound, and then removing the aluminum or aluminum alloy film. (2) A method for manufacturing a semiconductor device, wherein the step of depositing tungsten on the entire surface according to claim 1 comprises depositing tungsten on the entire surface after depositing a barrier metal on the entire surface. (3) forming an insulating film on the substrate; opening a contact hole on the insulating film using a photoresist as a mask; and depositing a tungsten film over the entire surface of the substrate with the photoresist remaining. a step of removing the tungsten film other than inside the contact hole and then removing the photoresist. (4) A method for manufacturing a semiconductor device, wherein the step of depositing a tungsten film on the entire surface according to claim 3 comprises depositing tungsten on the entire surface after depositing a barrier metal film on the entire surface.