JP2011077475A - Contact forming method and method for manufacturing semiconductor device - Google Patents

Abstract

A contact forming method and a semiconductor device manufacturing method capable of forming a contact with good controllability using a self-organizing material are provided.
A method of forming a contact formed on a substrate and electrically connecting different layers, wherein an interlayer insulating film formed on the first layer is etched, and a part of the first layer is etched Forming a contact hole exposing the polymer, forming a polymer film containing a conductive polymer block copolymer in the contact hole, phase-separating the polymer film, and exposing the contact hole Forming a contact having a conductive arrangement structure on the first layer, and forming a second layer on the contact.
[Selection] Figure 2

Description

  The present invention relates to a method for forming a contact for electrically connecting different layers in a semiconductor device and a method for manufacturing the semiconductor device.

  As is well known, it is well known that the opening of contact holes and further the formation of contacts have become difficult as the design rules become finer. In forming a resist pattern for forming a contact hole, a complicated illumination system is provided in an ArF immersion exposure machine, and a complicatedly designed mask is used, or a pattern is formed by multiple exposure.

  The time required for mask design becomes enormous as miniaturization progresses, and further, when multiple exposure is used, the number of processes increases, which causes a significant increase in time and manufacturing cost in the lithography process. In order to form a fine resist pattern, it is expected that the resist film thickness will be reduced as the miniaturization proceeds from the resolution performance of the resist. However, even if miniaturization progresses, the film thickness of the processed film is not reduced, and due to insufficient resistance to etching of the resist, a multilayer resist or a hard mask is used, which complicates the etching process and further takes an etching process. Time and cost are also increasing.

  In addition to the above problem, in order to form a contact by a filling process, it is difficult to form a seed layer uniformly in a fine contact hole or to form a metal layer. Currently, a metal film is used for the contact between the layers. However, as the contact hole becomes finer and the aspect ratio of the contact hole is improved, it is difficult to form a conductive layer in the contact hole with good embeddability. It has become.

  On the other hand, as a method for forming a fine pattern, a method that utilizes a phenomenon in which a material is phase-separated in a self-organized manner to form a specific regular array pattern has attracted attention. For example, in Patent Document 1, a block copolymer as a self-organizing material is dissolved in a solvent, and the solution is applied to the substrate surface by a spin coat method, a dip coat method, a solvent cast method, or the like. It is disclosed.

  In Patent Document 1, only one type of block copolymer film is formed on a substrate. In this case, a technique using a pattern obtained by phase separation of a block copolymer is disclosed.

JP 2007-125699 A

  A contact forming method and a semiconductor device manufacturing method capable of forming a contact with good controllability using a self-organizing material are provided.

  A contact formation method according to an aspect of the present invention is a contact formation method for electrically connecting different layers formed on a substrate, the interlayer insulating film formed on the first layer being etched, Forming a contact hole exposing a part of the first layer; forming a polymer film containing a conductive polymer block copolymer in the contact hole; and phase-separating the polymer film. And a step of forming a contact having a conductive array structure on the exposed first layer in the contact hole, and a step of forming a second layer on the contact. .

  A method for manufacturing a semiconductor device according to one embodiment of the present invention is a method for forming a contact formed on a semiconductor substrate and electrically connecting different layers, the interlayer insulating film formed on the first layer Forming a contact hole exposing a part of the first layer, forming a polymer film containing a conductive polymer block copolymer in the contact hole, and the polymer Forming a contact made of a conductive array structure on the exposed first layer in the contact hole, and forming a second layer on the contact. It is characterized by that.

  A contact forming method and a semiconductor device manufacturing method capable of forming a contact with good controllability using a self-organizing material are provided.

It is sectional drawing which showed typically the contact formation method which concerns on Example 1 of this invention. It is sectional drawing which showed typically the contact formation method which concerns on Example 1 of this invention. It is sectional drawing which showed typically the contact formation method which concerns on Example 2 of this invention. It is sectional drawing which showed typically the contact formation method which concerns on Example 2 of this invention. It is sectional drawing which showed typically the contact formation method which concerns on Example 2 of this invention. It is sectional drawing which showed typically the contact formation method which concerns on Example 2 of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 and 2 are cross-sectional views schematically showing a contact pattern forming method according to Embodiment 1 of the present invention. A contact pattern forming method according to Embodiment 1 of the present invention will be described with reference to FIGS. As shown in FIG. 1A, a wiring layer 1 is formed on a semiconductor substrate (not shown), and an interlayer insulating film 2 is formed around the wiring layer 1 and on the wiring layer 1. . Here, the wiring layer 1 is made of, for example, Cu, Cu alloy, Al, Al alloy, or the like. The interlayer insulating film 2 is made of, for example, a silicon oxide film. In this embodiment, the case where the contact for connecting the lower wiring layer and the upper wiring layer is formed will be described. However, the present invention is not limited to this, and the case for forming the contact for connecting the diffusion layer and the wiring layer is described. It is also applicable to.

  A resist pattern 3 for contact opening is formed on the interlayer insulating film 2 by a known lithography technique. A hard mask made of a silicon nitride film or the like may be used instead of the resist pattern 3. At this time, the size of the opening of the formed resist pattern 3 can be, for example, 1.5 to 2 times the desired contact hole size.

  Subsequently, as shown in FIG. 1B, the surface of the wiring layer 1 is exposed by etching the interlayer insulating film 2 using the resist pattern 3 as a mask by, for example, RIE (Reactive Ion Etching) or the like. After the interlayer insulating film 2 is etched to expose the surface of the wiring layer 1, the resist pattern 3 is removed to form a contact hole 4.

  Next, as shown in FIG. 1C, a polymer film 5 containing a conductive polymer block copolymer is formed inside the contact hole 4 and on the interlayer insulating film 2. This conductive polymer block copolymer has a structure in which a plurality of types of polymer chains are bonded. Each polymer chain has a single monomer chain structure. When this conductive polymer block copolymer is dissolved in an appropriate solvent at an appropriate concentration, the same kind of polymer chains are aggregated to form a block (phase) composed of the same kind of polymer chains. At this time, the heterogeneous phases are not sufficiently mixed with each other and develop a structure in which the heterogeneous phases are regularly arranged.

  In many cases, the conductive polymer block copolymer usually has a phase separation structure with low regularity because phase separation does not proceed sufficiently in the state as it is. Therefore, in this embodiment, for example, heat treatment is performed in order to sufficiently advance the phase separation and obtain a structure with higher regularity. For example, in order to prevent oxidation, heat treatment is performed for 30 hours at 210 ° C. above the glass transition temperature of each polymer chain in a hydrogen reduction atmosphere. Thereby, the conductive polymer block copolymer in the contact hole 4 is phase-separated in block units having a size corresponding to the molecular weight.

  By dissolving the conductive polymer block copolymer in a solvent, it is possible to easily embed the polymer film 5 in a fine contact hole. Therefore, by separating the polymer film 5 in the contact hole 4 into the conductive phase 6 and the insulating phase 7, a contact structure can be formed with good filling properties as shown in FIG. Here, the polymer film 5 on the interlayer insulating film 2 may or may not be phase separated.

  The solvent in which the conductive polymer block copolymer is dissolved may be applied to the entire surface of the wafer by spin coating, dip coating, solvent casting, or the like, and droplets are injected through an inkjet method and a fine needle tip tube. Alternatively, it may be applied selectively to a predetermined region, such as a microdispenser method, a method of dropping a microdroplet on a needle tip, or the like.

  Thereafter, as shown in FIG. 2B, the polymer film 5 on the interlayer insulating film 2 is removed and planarized to form a contact structure. Next, as shown in FIG. 2C, an upper wiring layer 8 that is electrically connected to the wiring layer 1 through a contact is formed.

  As described above, by using the contact pattern forming method according to the first embodiment of the present invention, it is possible to easily embed a conductive material selectively in a predetermined region in the contact hole. Moreover, since it is only necessary to form an opening having a size 1.5 to 2 times the desired contact hole size, the opening can be easily formed with good controllability.

  3 and 4 are cross-sectional views schematically showing a contact pattern forming method according to Embodiment 2 of the present invention. A contact pattern forming method according to the second embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 3A, a wiring layer 11 is formed on a semiconductor substrate (not shown), and an interlayer insulating film 12 is formed around and on the wiring layer 11. . Here, the wiring layer 11 is made of, for example, Cu, Cu alloy, Al, Al alloy, or the like. The interlayer insulating film 12 is made of, for example, a silicon oxide film. In this embodiment, the case where the contact for connecting the lower wiring layer and the upper wiring layer is formed will be described. However, the present invention is not limited to this, and the case for forming the contact for connecting the diffusion layer and the wiring layer is described. It is also applicable to.

  Further, an etching stopper film 13 made of, for example, a silicon nitride film may be formed below the interlayer insulating film 12 and on the wiring layer 11. The etching stopper film 13 is formed of a material having an etching selectivity with respect to the interlayer insulating film 12. In this embodiment, the case where the etching stopper film 13 is formed will be described.

  A resist pattern 14 for contact opening is formed on the interlayer insulating film 12 by a known lithography technique. A hard mask made of a silicon nitride film or the like may be used instead of the resist pattern 14. At this time, the size of the opening of the formed resist pattern 14 can be, for example, 1.5 to 2 times the desired contact hole size.

  Subsequently, as shown in FIG. 3B, the surface of the wiring layer 11 is exposed by etching the interlayer insulating film 12 and the etching stopper film 13 using the resist pattern 14 as a mask by, for example, RIE (Reactive Ion Etching) or the like. Let After the interlayer insulating film 12 and the etching stopper film 13 are etched to expose the surface of the wiring layer 12, the resist pattern 14 is removed to form a contact hole 15.

The etching process of the interlayer insulating film 12 and the etching stopper film 13 is performed by, for example, etching the interlayer insulating film 12 with a C ₄ F ₈ / Ar-based gas, and then CH ₂ F ₂ / O ₂ / CF ₄ -based or CH ₃ F. The contact hole 15 can be formed with high controllability by etching the etching stopper film 13 with a gas of / O ₂ / CF ₄ system.

  Next, as shown in FIG. 3C, a polymer film 16 containing a conductive polymer block copolymer having polarity is formed in the contact hole 15 and on the interlayer insulating film 12. This example differs from Example 1 described above in that a polymer film 16 including a conductive polymer block copolymer having polarity is formed.

  Also in the present embodiment, for example, heat treatment is performed in order to sufficiently advance the phase separation and obtain a structure with higher regularity. For example, in order to prevent oxidation, heat treatment is performed for 30 hours at 210 ° C. above the glass transition temperature of each polymer chain in a hydrogen reduction atmosphere. Thereby, the block copolymer inside the contact hole 15 is phase-separated.

  Here, since the conductive polymer block copolymer of this example has polarity, the conductive phase 17 having polarity is selectively formed on the wiring layer 11 as shown in FIG. It is formed. This conductive polymer block copolymer has a structure in which a plurality of types of polymer chains are bonded. Each polymer chain has a chain structure of one kind of monomer, and a metal is contained in a part of at least one kind of monomer. A polymer chain including a monomer containing a metal and having a polarity also has a polarity. When this conductive polymer block copolymer is dissolved in an appropriate solvent at an appropriate concentration, the same kind of polymer chains are aggregated to form a block (phase) composed of the same kind of polymer chains. At this time, the different phases are not sufficiently mixed with each other, and a structure in which the different phases are regularly arranged is expressed, and polymer chains made of polar monomers are aggregated on the wiring layer 11.

  The solvent in which the conductive polymer block copolymer is dissolved may be applied to the entire surface of the wafer by spin coating, dip coating, solvent casting, or the like, and droplets are injected through an inkjet method and a fine needle tip tube. Alternatively, it may be applied selectively to a predetermined region, such as a microdispenser method, a method of dropping a microdroplet on a needle tip, or the like.

  Thereafter, as shown in FIG. 4B, a contact structure can be formed by removing the polymer film 16 on the interlayer insulating film 12 and performing planarization. Next, as shown in FIG. 4C, an upper wiring layer 18 that is electrically connected to the wiring layer 1 through a contact is formed.

  The following effects can be obtained by using the conductive polymer block copolymer having the polarity shown in this example. As shown in FIG. 5A, when the opening of the resist pattern 14 is displaced with respect to the wiring layer 11 due to misalignment of the mask, for example, the contact hole 15 formed by etching using the resist pattern 14 as a mask is also formed in the wiring layer. 11 is displaced (FIG. 5B).

  With respect to such a structure, as shown in FIG. 5C, a polymer film 16 containing a conductive polymer block copolymer having polarity is formed inside the contact hole 15 and on the interlayer insulating film 12. Subsequently, when the polymer film 16 is phase-separated, the conductive phase is selectively formed on the wiring layer 11, so that the conductive phase 17 is formed on the wiring layer 11 as shown in FIG. A contact is formed. Therefore, even when the opening of the resist pattern 14 is shifted with respect to the wiring layer 11, the contact area between the contact structure and the wiring layer 11 can be reliably ensured, thereby suppressing the occurrence of product defects. Can do.

  As described above, by using the contact pattern forming method according to the second embodiment of the present invention, it is possible to easily embed a conductive material selectively in a predetermined region in the contact hole. Moreover, since it is only necessary to form an opening having a size 1.5 to 2 times the desired contact hole size, the opening can be easily formed with good controllability. In addition, even if misalignment between the contact hole and the wiring layer occurs, the contact area between the contact and the wiring layer can be reliably ensured.

DESCRIPTION OF SYMBOLS 1, 11 Wiring layer 2, 12 Interlayer insulation film 3, 14 Resist pattern 4, 15 Contact hole 5, 16 Polymer film 6, 17 Conductive phase 7 Insulating phase 8, 18 Upper wiring layer 13 Etching stopper film

Claims (5)

A method of forming a contact formed on a substrate and electrically connecting different layers,
Etching the interlayer insulating film formed on the first layer to form a contact hole exposing a part of the first layer;
Forming a polymer film containing a conductive polymer block copolymer in the contact hole;
Phase-separating the polymer film and forming a contact having a conductive arrangement structure on the exposed first layer in the contact hole;
Forming a second layer on the contact;
A contact forming method comprising:   The contact forming method according to claim 1, wherein a cross-sectional area of the contact hole is larger than a cross-sectional area of the contact.   The contact forming method according to claim 1, wherein the conductive polymer block copolymer has polarity.   The contact forming method according to claim 3, wherein the contact is selectively formed on the exposed first layer. A method of forming a contact formed on a semiconductor substrate and electrically connecting different layers,
Etching the interlayer insulating film formed on the first layer to form a contact hole exposing a part of the first layer;
Forming a polymer film containing a conductive polymer block copolymer in the contact hole;
Phase-separating the polymer film and forming a contact having a conductive arrangement structure on the exposed first layer in the contact hole;
Forming a second layer on the contact;
A method for manufacturing a semiconductor device, comprising:

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