JPH0529471A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve a controllability of an etching for forming a plug by a method wherein gas containing some one of at least F, Cl, Br and I is used as an etching means in the formation process of a buried conductor film. CONSTITUTION:Gas containing some one of at least F, Cl, Br and I is used as an etching means in the formation process of a buried conductor film. In the case an insulator film 2 is an oxide film like an SiO2 film, 0 atoms are eliminated from the SiO2 film by etching. Accordingly, as an etching using gas obtainable by adding a trace amount of O2 of 5% or thereabouts to HBr gas, for example, is reduced at a point of time when a polycrystalline silicon film 4a located at a part other than a contact hole 3 disappears by performing the etching, a possibility that even a plug 4 formed as the buried conductor film in the hole 3 is removed up by the etching as the etching rate is equal as the rate of that performed on the film 4a is dissolved and the control of the etching for forming the plug is facilitated.

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 an intermediate conductive layer called a plug between the upper and lower conductive layers through contact holes formed in the insulating layer. The present invention relates to an improvement in an etching method for partially etching the intermediate conductor film in the process of forming the intermediate conductor film when the conductive connection is made by the body film.

[0002]

2. Description of the Related Art Conventionally, in manufacturing a semiconductor device, after a lower conductor film is formed, the lower conductor film is covered with an insulating film (interlayer insulating film), and a contact hole is formed in the corresponding portion. An opening is made and the inside of the contact hole is filled with an intermediate conductor film called a plug, and then an upper conductor film is formed on an insulator film including this intermediate conductor film (hereinafter referred to as an embedded plug). Thus, a wiring forming means, that is, a so-called multi-layer wiring structure forming means for electrically connecting the upper and lower conductive films to each other is employed.

2 (a), (b) and (c) schematically show, in the order of main steps, an outline of means for forming a multi-layer wiring structure of this type which has been conventionally generally performed.

That is, in this general method for forming a multilayer wiring structure, after the lower conductor film 1 is selectively formed on a semiconductor substrate or the like, the lower conductor film 1 is covered with the insulator film 2. In a state in which the contact hole 3 is covered with a contact hole 3 in a corresponding portion, that is, a required portion including a connection portion for the lower conductor film 1, the contact hole 3 is first filled with a conductive material having a good filling property, for example, It is filled with a polycrystalline silicon film 4a formed by the CVD method (see FIG. 2 (a)).

Then, in the conventional case, the buried polycrystalline silicon film 4a is dry-etched by using plasma, usually by a fluorine-based gas such as SF ₆ , for example. Etching back is performed so as to leave the polycrystalline silicon film 4a only in the contact hole 3 to form a buried plug 4 as an intermediate conductor film (see FIG. 2 (b)).

After that, the upper conductor film 5 is selectively formed on the insulator film 2 including the buried plug 4 in the contact hole 3 (see FIG. 2 (c)). By electrically connecting the upper and lower conductor films 5 and 1 to each other with the interposition of the embedded plug 4, a desired multilayer wiring structure is formed.

Therefore, in the conventional multi-layer wiring structure formed through the above steps, even when a conductive material having a poor filling property such as a sputtered film is used as the upper conductor film 5, a contact is formed. Since the buried plug 4 is formed in the hole 3 in advance, the conductive portion in the contact hole 3 is well covered, the connection resistance is reduced, and there is no fear that a connection failure will occur.

By the way, in FIG. 3, the contact plugs 3 are not directly formed with the embedded plugs 4 in advance, but the contact holes 3 are directly embedded with a conductive material having a poor embedding property such as a sputtered film. Although the case where the required upper conductor film 5 is formed is shown, as is clear from FIG. 3, in this case, a thin film portion is formed on the inner wall portion and the bottom portion in the contact hole 3, The connection resistance will increase, or a connection failure such as disconnection will occur.

[0009]

However, in the above-mentioned conventional method of forming a multi-layer wiring, the contact hole 3 is formed.
In etching back the polycrystalline silicon film 4a embedded in the inside, since strong isotropic etching using a fluorine-based gas such as SF ₆ is performed, the following problems occur. .

That is, in the etching with the fluorine-based gas, generally, the smaller the etching area is, the higher the etching rate is. However, for this reason, the film to be etched is removed in a portion other than the contact hole. If it is lost, the etching rate increases, making control difficult, and sometimes even the portion corresponding to the plug is completely removed.

The present invention has been made in order to solve such a conventional problem, and an object thereof is that the etching rate for the film to be etched does not depend on the etching area and the etching area is narrow. To provide a method for manufacturing a semiconductor device of this kind, in which the etching speed is slowed down so that etching can be easily controlled, and a method for forming a multilayer wiring structure in the manufacture of a semiconductor device. Is.

[0012]

In order to achieve the above object, a method of forming a multi-layer wiring structure in the manufacture of a semiconductor device according to the present invention is characterized in that an insulating film is formed in an etching process during plug formation. If it contains atoms, at least
A gas-based etching means containing any of F, Cl, Br, and I is used, and if the insulator film contains O atoms or does not contain O atoms, at least one of F, Cl, Br, and I is used. A gas-based etching means in which a required amount of O ₂ is added to a gas containing such is used.

That is, according to the first aspect of the present invention, in the state in which a contact hole is opened in an insulating film containing O atoms on a lower conductive film, first, the insulating film including the inside of the contact hole is formed. While covering the intermediate conductor film, at least only the intermediate conductor film on the insulator film is removed by etching to leave the buried conductor film in the contact hole, and then the buried conductor film in the contact hole is removed. In the method of forming a multilayer wiring structure, an upper conductor film is formed on an insulating film including the upper conductor film and the upper conductor film and the lower conductor film are electrically connected by an embedded conductor film. In the method of manufacturing a semiconductor device, a gas system containing at least one of F, Cl, Br, and I is used as an etching means in the process of forming the buried conductor film.

According to a second aspect of the present invention, the contact hole is opened in the insulator film on the lower conductor film, and the intermediate conductor film is first formed on the insulator film including the inside of the contact hole. And at least only the intermediate conductor film on the insulator film is removed by etching to leave the buried conductor film in the contact hole, and then the insulator film including the buried conductor film in the contact hole. A method of forming a multilayer wiring structure, wherein an upper conductor film is formed on the upper conductor film and the upper conductor film and the lower conductor film are electrically connected to each other by the buried conductor film. A method for manufacturing a semiconductor device, characterized in that a gas system in which a required amount of O ₂ is added to a gas containing at least one of F, Cl, Br, and I is used as an etching means in the formation process of Is the law.

[0015]

Therefore, in the first aspect of the present invention, when the insulator film containing oxygen atoms is exposed as the etching progresses, the etching gas containing at least one of F, Cl, Br and I O atoms discharged from the exposed insulator film can be added to reduce the etching rate of the intermediate conductor film, and the buried conductor film can be formed with good controllability.

Further, in the second aspect of the present invention, a gas system in which a required amount of O ₂ is added to a gas containing at least one of F, Cl, Br and I is used as the etching means. In the case of an insulating film containing, when the insulating film is exposed, the discharged O atom is further added to the etching gas to reduce the etching rate of the intermediate conductor film and to contain the O atom. In the case of a non-insulating film, the embedded conductive film can be formed with good controllability since the etching rate of the intermediate conductive film is reduced from the beginning of etching as well.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a semiconductor device according to the present invention, hereunder, an embodiment of a method of forming a multi-layer wiring structure in the manufacture of a semiconductor device will be described in detail with reference to FIGS. .

In the method of one embodiment of the present invention, the polycrystalline silicon film 4a is formed by using a gas system in which O ₂ is added to HBr gas during the etching in the step (b) after the step in FIG. 2 (a). Then, the multilayer wiring structure is similarly formed through the step (c) of etching back.

FIG. 1 shows the etching rate in polycrystalline silicon when a gas-based etching means in which O ₂ is added to HBr gas is used as a method of one embodiment of the present invention.
The graph shows the dependence of O ₂ addition amount.

That is, as is apparent from FIG. 1, when O ₂ is added to HBr gas in an amount of 5% or more, the etching rate sharply decreases. It turns out that it hardly progresses.

Here, the insulator film 2 in the step of FIG. 2 (b) is used.
Is, for example, an oxide film such as a SiO ₂ film,
O atoms are discharged from the SiO ₂ film during etching. And, for this reason, as described above, HBr gas is added.
When the polycrystalline silicon film 4a is etched back using a gas system to which about 5% O ₂ is added, the polycrystalline silicon film 4a other than the contact holes 3 is removed and disappears as the etching progresses. And Si as the insulator film 2
At the time when the O ₂ film is exposed, O atoms are ejected from the SiO ₂ film, and as a result, the subsequent polycrystalline silicon film 4a is removed.
The etching rate is reduced.

Therefore, by performing the etching using the gas system in which the trace amount of O ₂ is added to the HBr gas as described above, when the polycrystalline silicon film 4a other than the contact hole 3 disappears. Since the etching rate is reduced, there is no fear that the plug 4 as the embedded conductor film in the contact hole 3 is etched and removed at the same speed as in the conventional method. This facilitates the etching control.

In the method of the above embodiment, HBr is used as the etching gas for forming the buried plug.
Although the case where the gas system in which O ₂ is added to the gas is used has been described, substantially the same action and effect are obtained when the gas system in which O ₂ is added to the gas containing F, Cl, Br, I is used. can get.

In the method of the above-described embodiment, the case where the conductor film forming the plug is a polycrystalline silicon film has been described. However, it may be a metal film of W, Ti or the like, or WSi _x , TiSi. Of course, it may be a metal silicon compound such as _x .

Further, depending on the etching conditions in the case of having an oxide-based insulating film, even if the amount of O ₂ added is reduced, or even if O ₂ is not added, the oxide-based insulating film By supplying O atoms from the body membrane, the required actions and effects can be obtained.

[0026]

As described above in detail with reference to the embodiments,
According to the first invention method of the present invention, on the lower conductor film
A contact hole is opened in the insulator film containing O atoms, the intermediate conductor film is covered on the insulator film including the inside of the contact hole, and at least only the intermediate conductor film on the insulator film is removed by etching. The buried conductor film is left in the contact hole, and an upper conductor film is formed on the insulator film including the buried conductor film in the contact hole. In a method of forming a multi-layer wiring structure in which mutual conduction is made by a buried conductor film, at least as an etching means in the process of forming the buried conductor film,
Since a gas system containing any of F, Cl, Br, and I was used, when the insulator film containing O atoms was exposed as the etching progressed, the insulator film was exposed to the etching gas. The discharged O atoms are added, and as a result, the etching rate of the intermediate conductor film is reduced, and the required buried conductor film can be formed extremely easily and with good controllability.

Further, according to the second invention of the present invention, in the above-mentioned method for forming a multilayer wiring structure, a gas containing at least any one of F, Cl, Br and I is used as the etching means, and a required amount of O _{2 is used.} In the case of an insulator film containing O atoms, since a gas system added with is used, when this insulator film is exposed,
The discharged O atoms are further added to the etching gas to reduce the etching rate of the intermediate conductor film, and
In the case of an insulator film that does not contain atoms, the etching rate of the intermediate conductor film is reduced from the beginning of etching, and similarly, the required embedded conductor film can be formed very easily and with good controllability. To get.

[Brief description of drawings]

FIG. 1 is a graph showing the dependence of the etching rate of polycrystalline silicon on the amount of added O ₂ when a gas-based etching means in which O ₂ is added to HBr gas according to an embodiment method of the present invention is used.

2A to 2D are cross-sectional views schematically showing an outline of a general method of forming a multilayer wiring structure including an embodiment method of the present invention and a conventional method in the order of main steps.

FIG. 3 is a cross-sectional view schematically showing a schematic configuration of a multilayer wiring structure formed by a conventional method without filling a contact hole with a plug.

[Explanation of symbols]

1 Lower conductor film 2 Insulator film 3 contact holes 4a Polycrystalline silicon film 4 Embedded plug (embedded intermediate conductor film) 5 Upper conductor film

Claims (2)

[Claims] 1. In a state in which a contact hole is opened in an insulating film containing O atoms on a lower conductive film, first, an intermediate conductive film is coated on the insulating film including the inside of the contact hole, and At least only the intermediate conductor film on the insulator film is removed by etching to leave the buried conductor film in the contact hole, and then the upper conductor on the insulator film including the buried conductor film in the contact hole. In a method of forming a multilayer wiring structure in which a film is formed so that the upper and lower conductor films are electrically connected to each other by a buried conductor film, the etching in the process of forming the buried conductor film is performed. A method of manufacturing a semiconductor device, characterized in that a gas system containing at least one of F, Cl, Br, and I is used as a means. 2. In a state where a contact hole is opened in an insulating film on a lower conductive film, first, an insulating film including the inside of the contact hole is covered with an intermediate conductive film, and at least the insulating film is formed. Only the intermediate conductor film on the film is removed by etching to leave the buried conductor film in the contact hole, and then the upper conductor film is formed on the insulator film including the buried conductor film in the contact hole. In the method of forming a multi-layer wiring structure in which the upper and lower conductor films are electrically connected to each other by the buried conductor film, at least as an etching means in the process of forming the buried conductor film, A method for manufacturing a semiconductor device, which uses a gas system in which a required amount of O ₂ is added to a gas containing any one of F, Cl, Br, and I.