The present application is based on Japanese Priority Patent Application No. 2005-327878, filed on Nov. 11, 2005, the entire contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates generally to methods of manufacturing a semiconductor device, and more particularly to a method of manufacturing a semiconductor device which method forms an interconnection structure by a dual damascene process.
2. Description of the Related Art
In recent years, as semiconductor devices have been provided with more functions and become more sophisticated, there has been pursued high integration in which a significant increase in the number of transistors mounted on a single chip and a reduction in chip size progress simultaneously. With this high integration of semiconductor devices, it is required to increase the number of interconnections with a reduced chip size, so that interconnection structures with higher density have been pursued.
As interconnection structures are provided with higher density, interconnection delay due to a so-called “RC product,” the product of an increase in interconnection capacitance C because of reduction in the distance between interconnections and an increase in interconnection resistance R because of reduction in interconnection width, increases.
In order to solve this problem and to reduce interconnection capacitance, a film of low dielectric constant material, a so-called “low-k” film, has been used for an interlayer insulating film. The low-k film has a lower dielectric constant than a silicon oxide film (SiO2, a relative dielectric constant of approximately 4.3), conventionally used as an interlayer insulating film. As low-k films, inorganic insulating films of SiOC or porous silica and polyimide-based or Teflon (registered trademark)-based organic insulating films have been proposed.
Further, in order to reduce interconnection delay and to reduce interconnection resistance R, interconnection structures formed by the dual damascene process using Cu interconnections have been employed. In the dual damascene process, a via that is a vertical interconnection and the interconnection of an interconnection layer are formed at the same time. According to the dual damascene process, a via hole and an interconnection trench are formed and, thereafter, filled with Cu. The surface of Cu is flattened by chemical mechanical polishing (CMP). As one dual damascene method, a so-called “via-first” method, first forming a via hole and then forming an interconnection trench, is employed.
In this respect, reference may be made to Japanese Laid-Open Patent Application No. 2003-229481.
The low-k film used for each of the interlayer insulating films 103 and 104 has not only a lower relative dielectric constant but also a lower density than the silicon oxide film. Accordingly, the low-k film has the property of being likely to absorb a process gas and an etching gas used in its formation, and retaining an extremely greater amount of gas than the silicon oxide film.
Referring to
Accordingly, it is a general object of the present invention to provide a method of manufacturing a semiconductor device in which the above-described disadvantage is eliminated.
A more specific object of the present invention is to provide a method of manufacturing a semiconductor device which method is capable of preventing resist poisoning and forming a fine interconnection structure.
The above objects of the present invention are achieved by a method of manufacturing a semiconductor device, the method forming an interconnection structure by a dual damascene process, the method including the steps of: (a) forming a first interlayer insulating film and a second interlayer insulating film successively over an interconnection layer, at least one of the first interlayer insulating film and the second interlayer insulating film being formed of a low dielectric constant material; (b) forming a via hole through the first interlayer insulating film and the second interlayer insulating film; (c) filling the via hole with a burying material formed of a material including an acid generator; (d) causing an acid substance to be generated in the burying material; (e) forming a chemically amplified resist film covering the second interlayer insulating film and the burying material; (f) forming a pattern of an interconnection trench in an area including the via hole over the chemically amplified resist film; (g) forming the interconnection trench by etching the second interlayer insulating film using the chemically amplified resist film as a mask; and (h) filling the via hole and the interconnection trench with a conductive material.
The above objects of the present invention are also achieved by a method of manufacturing a semiconductor device, the method forming an interconnection structure by a dual damascene process, the method including the steps of: (a) forming a cap layer, a first interlayer insulating film of a low dielectric constant material, an etching stopper layer, a second interlayer insulating film of a low dielectric constant material, and a hard mask layer successively over an interconnection layer; (b) forming a via hole exposing a surface of the cap layer by etching the first interlayer insulating film, the etching stopper layer, the second interlayer insulating film, and the hard mask layer; (c) forming a burying material of a material including an acid generator so that the via hole is filled and a surface of the hard mask layer is covered with the burying material; (d) causing an acid substance to be generated in the burying material by irradiating a substantially entire surface of the burying material with energy lines; (e) heating the burying material, the first interlayer insulating film, and the second interlayer insulating film; (f) forming a chemically amplified resist film covering the hard mask layer and the burying material; (g) forming a pattern of an interconnection trench in an area including the via hole over the chemically amplified resist film; (h) forming the interconnection trench by etching the second interlayer insulating film using the chemically amplified resist film as a mask; and (i) filling the via hole and the interconnection trench with a conductive material.
According to one aspect of the present invention, by using a material including an acid generator generating an acid substance as a burying material with which a via hole is filled, it is possible to neutralize a basic substance occluded in an interlayer insulating film of a low dielectric constant material, and to prevent the basic substance from acting on an acid substance generated by exposure of a chemically amplified resist film. As a result, it is possible to prevent occurrence of resist poisoning and thus form a fine interconnection structure.
That is, according to one aspect of the present invention, by using a material generating an acid substance as a burying material to fill in a via hole, it is possible to provide a semiconductor device manufacturing method capable of forming a fine interconnection structure by preventing occurrence of resist poisoning.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings, in which:
The inventors of the present invention have analyzed the cause of poisoning and made the present invention as follows. That is, for example, in a resist film formed of a positive chemically amplified resist material, an acid substance is generated in the area illuminated with exposure light by an acid generator included in the resist material. Next, when the resist film is heated (for example, prebaked), the acid substance decomposes a dissolution inhibitor so as to convert the resist film into a structure soluble in alkaline development liquid. At the time of this exposure or heating, as shown in
The inventors of the present invention have found that it is possible to prevent resist poisoning by employing a burying material that generates a substance to neutralize the basic substance so as to prevent the basic substance from reaching the resist film 110.
In the specification of the present application, a low dielectric constant material (also referred to as “low-k material”) refers to a material having a lower dielectric constant than a silicon oxide film (SiO2, with a relative dielectric constant of approximately 4.3). Further, a low-k film refers to a film formed of a low-k material.
A description is given below, with reference to the accompanying drawings, of embodiments of the present invention.
First, in the process of
As the first interlayer insulating film 13 and the second interlayer insulating film 15, in addition to a SiOC film, also employable are such low-k films as: inorganic insulting films such as SiOF and BSG (SiO2—B2O3) films with relative dielectric constants of 3.5-3.7; porous silica such as Nano Clustering Silica (NCS, the name of a Catalysts & Chemicals Industries Co., Ltd. product) and Porous SiLK (registered trademark) Y (the name of a Dow Chemical Company product) with a relative dielectric constant of 2.4; and organic siloxane such as porous Black Diamond (the name of an Applied Materials Inc. product), CORAL (registered trademark, a Novellus Systems Inc. product) with a relative dielectric constant of 3.2, and HOSP (registered trademark, a Honeywell Electronic Materials product) with a relative dielectric constant of 2.5.
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Further, as the protection film 22, for example, an antireflection film of a SiN film formed with a plasma CVD apparatus using a mixture of SiH4 gas, NH3 gas, and N2 gas is used. By suitably selecting the flow rate of each gas and heating temperature, it is possible to prevent reflection of exposure light from the underlayer at the time of exposing the resist film 23, so that finer patterning is performable. The protection film 22 further flattens the surface of the burying material 21, so that it is possible to further flatten the surface of the resist film 23.
The protection film 22 may be a layered body of a resin material film and an inorganic material film stacked in this order. The resin material film is, for example, a resist film of a type other than the chemically amplified type. The inorganic material film is, for example, a silicon oxide film or a spin-on-glass (SOG) film. As a result of this, the same effect as that of the above-described antireflection film is produced.
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According to the first embodiment, the burying material 21 generates an acid substance so as to neutralize the basic substance occluded in the low-k films. Accordingly, the basic substance is prevented from affecting the acid substance of the resist film 23 for forming the pattern of the interconnection trench 15a. Accordingly, it is possible to prevent occurrence of resist poisoning, thus making it possible to form a minute interconnection structure.
In the above-described first embodiment, each of the first and second interlayer insulating films 13 and 15 is formed of a low-k material. Alternatively, however, one of the first and second interlayer insulating films 13 and 15 may be formed of a low-k material, and the other may be formed of an insulating film material other than the low-k material, such as a TEOS film.
Next, a description is given of an example according to the first embodiment.
In this example, as a material for the burying material (21a or 21) of the first embodiment, a negative resist material formed of PVP resin as a base resin, a melamine compound as a crosslinker, and an onium salt as an acid generator was used. In this negative resist material, the acid generator is caused to generate an acid substance by irradiation of KrF rays.
On the other hand, in a comparative example, novolac resin was used as a material for the burying material of the first embodiment. Irradiation of light or heating does not cause this material (novolac resin) to generate an acid substance. Further, the comparative example was formed by the same process as the example except that a different burying material was employed.
Using the burying materials of the above-described example and comparative example, irradiation of KrF rays was performed with an exposure of 700 J/m2, and then heating was performed at 130° C. for 90 seconds in the above-described process of
Further, in each of the example and the comparative example, in the above-described structure shown in
In the comparative example shown in
A method of manufacturing a semiconductor device according to a second embodiment of the present invention is equal to that of the first embodiment except that a negative chemically amplified resist material is used as the burying material 21a or 21. In the drawing, the same elements as those described above are referred to by the same numerals, and a description thereof is omitted.
In the process of manufacturing a semiconductor device according to the second embodiment, first, the same processes as those of
Next, in the process of
According to the second embodiment, as a result of using a negative chemically amplified resist material as a material for the burying material 21b, the burying material 21b is converted into a structure insoluble in development liquid. Therefore, there is no need to provide a protection film protecting the burying material 21b from development liquid. Further, the number of processes can be less than that of the manufacturing method of the first embodiment, so that it is possible to simplify the manufacturing process. The manufacturing method according to the second embodiment produces the same effect as that of the manufacturing method of the first embodiment.
According to one aspect of the present invention, by using a material including an acid generator generating an acid substance as a burying material with which a via hole is filled, it is possible to neutralize a basic substance occluded in an interlayer insulating film of a low dielectric constant material, and to prevent the basic substance from acting on an acid substance generated by exposure of a chemically amplified resist film. As a result, it is possible to prevent occurrence of resist poisoning and thus form a fine interconnection structure.
That is, according to one aspect of the present invention, by using a material generating an acid substance as a burying material to fill in a via hole, it is possible to provide a semiconductor device manufacturing method capable of forming a fine interconnection structure by preventing occurrence of resist poisoning.
The present invention is not limited to the specifically disclosed embodiments, and variations and modifications may be made without departing from the scope of the present invention.
Number | Date | Country | Kind |
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2005-327878 | Nov 2005 | JP | national |