Abstract:
Methods of forming devices include forming a first electrically insulating layer having a metal interconnection therein, on a substrate and then forming a first electrically insulating barrier layer on an upper surface of the metal interconnection and on the first electrically insulating layer. The first electrically insulating barrier layer is exposed to a plasma that penetrates the first electrically insulating barrier and removes oxygen from an upper surface of the metal interconnection. The barrier layer may have a thickness in a range from about 5 Å to about 50 Å and the plasma may be a hydrogen-containing plasma that converts oxygen on the upper surface of the metal interconnection to water.

Description:
FIELD OF THE INVENTION 
   The present invention relates to semiconductor device fabrication methods and, more particularly, to methods of forming semiconductor devices with copper interconnects therein. 
   BACKGROUND OF THE INVENTION 
   Copper (Cu) has been used as an interconnection material in order to reduce the resistance of interconnections. In the case of forming a copper interconnection, a damascene process is generally used. In the damascene process, chemical mechanical polishing (CMP) may be performed, and after the CMP process is performed, a thin copper oxide film may be formed on the copper interconnection. A copper oxide film may be formed because it is difficult to completely intercept oxygen during the CMP process, and slurries used in the CMP process typically contain oxygen components. If a copper oxide film exists on the copper interconnection, the adhesion of the copper connection to a layer deposited on the copper interconnection may be degraded, and the interconnection resistance may be increased, thereby deteriorating the reliability of the semiconductor device. 
   Generally, in order to remove the copper oxide film, a plasma process may be performed with respect to a semiconductor substrate. If the plasma process is performed with respect to the semiconductor substrate, carbon components of an insulating layer may be removed by the plasma, and thus the carbon content of the insulating layer may be reduced. Also, a low dielectric material (i.e., a low-k material) that is mainly used as a material of the insulating layer may be porous and have a low mechanical solidity. Accordingly, when a plasma process is performed with respect to the insulating layer formed of a low-k material, the porosity of the insulating layer may be further increased if carbon is removed therefrom, and this increase in porosity may decrease the reliability of the semiconductor device. 
   Typically, in order to completely remove a copper oxide film, a long-time plasma process is required. However, as the plasma process is performed for a longer time, the thickness of the insulating layer being damaged by carbon removal becomes greater. Accordingly, if the plasma process is performed for a long time to completely remove the copper oxide film, the thickness of the damaged insulating layer, for example, may be about 1000 Å. 
   If the thickness of the damaged insulating layer is increased, then electron movement therein may occur and cause current leakage to neighboring interconnections. The porosity of the insulating layer may also be increased and thereby shorten the lifetime of the device. However, if the plasma process is weakly performed in order to reduce the thickness of the damaged insulating layer, the copper oxide layer may not be completely removed. Consequently, there is a need for a technique that can make the damaged insulating layer thin while completely removing the copper oxide layer. 
   SUMMARY OF THE INVENTION 
   Methods of forming an integrated circuit device according to embodiments of the present invention include forming a first electrically insulating layer having a metal interconnection therein, on a substrate, and forming a first electrically insulating barrier layer on an upper surface of the metal interconnection and on the first electrically insulating layer. The first electrically insulating barrier layer is exposed to a plasma that removes oxygen from an upper surface of the metal interconnection. According to preferred aspects of these embodiments, the first electrically insulating barrier layer has a thickness in a range from about 5 Å to about 50 Å and the plasma is a hydrogen-containing plasma that penetrates the barrier layer and converts oxygen on the upper surface of the metal interconnection to water, which out-diffuses from the barrier layer. The metal interconnection may be formed as a copper damascene pattern having a copper oxide layer thereon and the barrier layer may be at least one of SiN, SiC and SiCN. 
   Additional embodiments of the present invention include forming a first electrically insulating layer having a metal interconnection therein, on a substrate, and then removing oxygen from an upper surface of the metal interconnection by exposing the upper surface of the metal interconnection and the first electrically insulating layer to a first oxygen-removing plasma. Then, a first electrically insulating barrier layer may be formed on the upper surface of the metal interconnection and on the first electrically insulating layer. Additional oxygen may then be removed from the upper surface of the metal interconnection by exposing the first electrically insulating barrier layer to a second oxygen-removing plasma that converts oxygen on the upper surface of the metal interconnection to water, which out-diffuses through the insulating barrier layer. According to preferred aspects of these embodiments, the first oxygen-removing plasma comprises ammonia (NH 3 ) and the second oxygen-removing plasma comprises hydrogen. The step of exposing the first electrically insulating barrier layer to a second oxygen-removing plasma may be followed by forming a second electrically insulating barrier layer on the first electrically insulating barrier layer. These first and second electrically insulating barrier layers may be formed as SiN, SiC or SiCN layers. 
   According to additional embodiments of the present invention, a method of forming an integrated circuit device includes forming a first electrically insulating layer of SiCOH, on a semiconductor substrate, and then forming a metal interconnect comprising copper and a copper oxide region, within a recess in the first electrically insulating layer. A first electrically insulating barrier layer is then formed on an upper surface of the metal interconnect. At least a portion of the copper oxide region is then converted to copper metal by exposing the electrically insulating barrier layer to a hydrogen-containing plasma that transfers free hydrogen through the electrically insulating barrier layer to the copper oxide region. A second electrically insulating barrier layer is then formed on the first electrically insulating barrier layer. The first electrically insulating barrier layer may have a thickness in a range from about 5 Å to about 50 Å and the first electrically insulating layer may be a SiCOH layer. The combined thickness of the first and second electrically insulating barrier layers may also be greater than about 250 Å. In addition, the step of forming a first electrically insulating barrier layer on an upper surface of the metal interconnect may be preceded by exposing the copper oxide region to a plasma containing ammonia to thereby convert at least some of the copper oxide to copper. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and advantages of the present invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a flowchart illustrating a method of fabricating a semiconductor integrated circuit device according to an embodiment of the present invention; 
       FIGS. 2 to 9  are cross-sectional views of intermediate structures that illustrate methods of fabricating semiconductor integrated circuit devices according to the embodiments of the present invention illustrated by  FIG. 1 ; 
       FIG. 10  is a flowchart illustrating a method of fabricating a semiconductor integrated circuit device according to an additional embodiment of the present invention; and 
       FIGS. 11 to 13  are cross-sectional views of intermediate structures that illustrate methods of fabricating semiconductor integrated circuit devices according to embodiments of the present invention illustrated by  FIG. 10 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. 
   It will be understood that when an element or layer is referred to as being “on,” “connected to” or “coupled to” another element or layer (and variants thereof), it can be directly on, connected or coupled to the other element or layer or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to” or “directly coupled to” another element or layer (and variants thereof), there are no intervening elements or layers present. Like reference numerals refer to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
   It will be understood that, although the terms first, second, odd, even, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first or odd element, component, region, layer or section discussed below could be termed a second or even element, component, region, layer or section without departing from the teachings of the present invention. 
   Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper,” “top,” “bottom” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. It also will be understood that, as used herein, the terms “row” or “horizontal” and “column” or “vertical” indicate two relative non-parallel directions that may be orthogonal to one another. However, these terms also are intended to encompass different orientations. 
   The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” “including” and variants thereof, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
   Example embodiments of the present invention are described herein with reference to cross-section illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the present invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, example embodiments of the present invention should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an implanted region illustrated as a rectangle will, typically, have rounded or curved features and/or a gradient of implant concentration at its edges rather than a binary change from implanted to non-implanted region. Likewise, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation takes place. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the present invention. 
   Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
   Hereinafter, a method of fabricating a semiconductor integrated circuit device according to embodiments of the present invention will be described with reference to the accompany drawings.  FIG. 1  is a flowchart illustrating a method of fabricating a semiconductor integrated circuit device according to an embodiment of the present invention, and  FIGS. 2 to 9  are sectional views successively explaining the method of fabricating a semiconductor integrated circuit device according to an embodiment of the present invention. 
   Referring to  FIGS. 1 and 2 , an insulating layer  110   a  is formed on a semiconductor substrate  100  (Step S 110 ). The semiconductor substrate  100  may be a silicon substrate, an SOI (Silicon On Insulator) substrate, a gallium arsenide (GaAs) substrate, a silicon germanium substrate, a ceramic substrate, a quartz substrate, or a glass substrate for a display, for example. Also, a P-type substrate or an N-type substrate may be used as the semiconductor substrate, but the P-type substrate is typically used. In this case, although not illustrated in the drawings, a P-type epitaxial layer may be grown on an upper part of the semiconductor substrate  100 . And, although not illustrated in the drawings, the semiconductor substrate  100  may include a P-type well or an N-type well doped with p-type or n-type impurities. On the semiconductor substrate  100 , transistors, contact holes, lower interconnections and other device structures (not shown) may be formed. The insulating layer  110   a  may be a silicon oxide layer such as SiO 2 , and may be formed of a low dielectric (low-k) material. The low-k material may be a material having a dielectric constant k of about 3.0 or less, such as carbon containing silicon oxide (SiCOH). 
   Then, as shown in  FIGS. 1 and 3 , a recess  120  is formed in the insulating layer  110   a  (Step S 120 ). The recess  120  is formed by patterning a specified part of the insulating layer  110   a , for example, by a photolithography process. Here, although the recess is in the form of a single damascene pattern in the drawing, it may be formed as a dual damascene interconnection in alternative embodiments of the invention. 
   Then, as shown in  FIGS. 1 and 4 , a damascene interconnection layer  130   a  is formed so as to completely fill in the recess  120  (Step S 130 ). In this case, the damascene interconnection layer  130   a  may include a first metal layer  131   a  and a second metal layer  132   a . Specifically, the first metal layer  131   a  is conformally deposited on the insulating layer  110   a , which includes a lower surface and side walls of the recess  120 . The first metal layer  131   a  may be deposited, for example, by CVD (Chemical Vapor Deposition) or PVD (Physical Vapor Deposition). Also, the first metal layer  131   a  may be formed of titanium (Ti), tantalum (Ta), tungsten (W), or their nitride, such as TiN, TaN, WN. Alternatively, the first metal layer may be formed of TaSiN, WsiN or TiSiN. Here, the first metal layer  131   a  can act as a barrier layer by preventing metal atoms in the second metal layer  132   a  from being diffused into the surrounding insulating layer  110   a.    
   Thereafter, a second metal layer  132   a  is deposited so as to completely fill in the recess  120 . The second metal layer  132   a  may be made of copper or copper alloys, but is not limited thereto. The copper alloy may be obtained by mixing a very small amount of an element, for example, C, Ag, Co, Ta, In, Sn, Zn, Mn, Ti, Mg, Cr, Ge, Sr, Pt, Mg, Al, or Zr, in copper, but is not limited thereto. The second metal layer  132   a  may also be deposited by CVD or PVD. Although not illustrated in the drawing, a seed metal layer may be further formed on the first metal layer  131   a , prior to deposition of the second metal layer  132   a . The seed metal layer can increase the uniformity of the metal layer, and serve as an initial nucleation site. The seed metal may be copper, gold, silver, platinum (Pt), Palladium (Pd), but is not limited thereto. 
   Then, as shown in  FIGS. 1 and 5 , a damascene interconnection  130  is formed through a smoothing process (Step S 140 ). The damascene interconnection  130  may be formed by smoothing a damascene interconnection layer  130   a  until the upper surface of the insulating layer  110   a  is exposed. The smoothing of the damascene interconnection layer  130   a  may be performed, for example, by CMP (Chemical Mechanical Polishing). However, since it is difficult to completely shut out oxygen while performing the CMP, and oxygen components may be included in slurries for use in CMP, a thin metal oxide layer  140  may be formed on an upper surface of the damascene interconnection  130  during the step of smoothing the damascene interconnection layer  130   a . In this case, the metal oxide layer  140  may be formed to a thickness A of about 50 Å. Particularly, in the case of forming the second metal layer  132   a  with copper or its alloys, a copper oxide layer such as CuOx may be formed as the thin metal oxide layer  140 . 
   Then, as shown in  FIGS. 1 and 6 , a first plasma process  150  is performed with respect to the semiconductor substrate  100  on which the damascene interconnection  130  is formed (Step S 150 ). Specifically, the semiconductor substrate  100 , on which the damascene interconnection  130  is formed, is put in a plasma-processing device (not illustrated), and the first plasma process  150  is performed, for example, by injecting a gas including NH 3  into the device. When the first plasma process  150  is performed, a part of the metal oxide layer  140 , formed on the upper side of the damascene interconnection  130 , is deoxidized. About 50% to 90% of the metal oxide layer  140 , and preferably at least about 33% of the metal oxide layer  140 , may be deoxidized, to thereby yield an at least partially deoxidized metal oxide layer  141 . 
   In addition, since the first plasma process  150  is performed not only with respect to the metal oxide layer  140 , but is performed with respect to the entire semiconductor substrate  100 , the first plasma process  150  may affect the insulating layer  110   a  formed on the semiconductor substrate  100  as shown in  FIG. 5 . Accordingly, in order to minimize the effect of the first plasma process  150  upon the insulating layer  110   a , the first plasma process  150  is performed under weaker plasma conditions. For example, the plasma process  150  may be performed at a power of about 50 to 300 W for about 5 to 30 sec. In this case, the power and the processing time are complementary to each other. If a low power is supplied, the plasma process is performed for a relatively long time, while if a high power is supplied, the plasma process is performed for a relatively short time. For example, if a power of 50 W is supplied, the plasma is performed for about 30 sec. 
   After the completion of the first plasma process, the insulating layer  110   a  on the semiconductor substrate  100  may be divided into an upper region  111  and a lower region  112 , to yield a modified insulating layer  110   b . The upper region  111  indicates a region in which the insulating layer is damaged due to the first plasma process. Specifically, when the plasma, which is formed by using a gas including NH 3  reaches the surface of the insulating layer  110   a , carbon atoms of the insulating layer  110   a  may be removed for the case where the insulating layer  110   a  is SiCOH. That is, during the plasma process, the carbon atoms of the upper region  111  may be removed, and thus the carbon content of the upper region  111  may be reduced. The removal of the carbon atoms may cause spaces to form in the upper region  111 , and so the upper region  111  may become more porous than the lower region  112 . However, since the metal oxide layer  140  is partly deoxidized under a weaker condition by the first plasma process, a thickness B of the upper region  111  of the damaged insulating layer  110   a  may be in a range from 50 Å to about 500 Å. Accordingly, the thickness of the damaged upper region  111  may be reduced to thereby improve the reliability of the device. 
   Thereafter, as shown in  FIGS. 1 and 7 , a first barrier layer  161   a  is formed on the damascene interconnection  130  and the insulating layer  110   b  (Step S 160 ). The first barrier layer  161   a  may be formed by CVD or PECVD using a plasma deposition process. The first barrier layer  161   a  may be formed, for example, with silicon nitride (SiN), silicon carbide (SiC), or silicon carbon nitride (SiCN). The first barrier layer  161   a  may serve to provide electrical insulation to the damascene interconnection  130 , or serve as a stopper in the etching process for forming another damascene interconnection (not illustrated). Although the first barrier layer  161   a  can protect the upper region  111  of the insulating layer while a second plasma process is performed, it is necessary for ions and radicals to pass through the first barrier layer  161   a . Thus, the first barrier layer  161   a  has a thickness C, which is enough to prevent the upper region  111  of the insulating layer  110   b  from being damaged due to the second plasma process, but thin enough to allow ions and radicals to pass through the first barrier layer  161   a  during the second plasma process. The thickness C of the first barrier layer  161   a  may be about 5 to 50 Å, and be preferably about 20 Å. 
   Then, as shown in  FIGS. 1 and 8 , the second plasma process  170  is performed with respect to the semiconductor substrate  100  on which the first barrier layer  161   a  is formed (Step S 170 ). The semiconductor substrate  100 , on which the first barrier layer  161   a  is formed, is put in a plasma processing device (not illustrated), and a second plasma process  170  is performed by injecting a gas including hydrogen. The hydrogen ions and hydrogen radicals included in the plasma pass through the first barrier layer  161   a , and may completely deoxidize the metal oxide layer  141  on the damascene interconnection  130 . At this time, H2O, which is a by-product of the interaction between the metal oxide layer  141  and hydrogen radicals, is discharged from the first barrier layer  161   a . The second plasma process may be performed for about 10 to 60 sec. When the second plasma process is completed, the metal oxide layer  141  that exists between the damascene interconnection  130  and the first barrier layer  161   a  may be completely deoxidized. 
   Then, as shown in  FIGS. 1 and 9 , a second barrier layer  162  is formed on the first barrier layer  161   a  (Step S 180 ). The second barrier layer  162  may be made of substantially the same material as the first barrier layer  161 . Also, the second barrier layer  162  may be formed by CVD or PECVD in the same manner as the first barrier layer  161 . 
   In this case, if the thickness D of the barrier layer  160 , including the first barrier layer  161   a  and the second barrier layer  162 , is not sufficient, oxygen may pass through the barrier layer  160  and be injected into the damascene interconnection  130 . Accordingly, it is desirable that the thickness D of the barrier layer  160  be sufficient to intercept the transmission of oxygen through the barrier layer  160 . Accordingly, the second barrier layer  162  and the first barrier layer  161   a  are formed to a thickness of at least about 250 Å. 
   According to the method of fabricating a semiconductor integrated circuit device according to an embodiment of the present invention, the first plasma process is formed under weaker conditions, and the region in which the insulating layer is deoxidized can be reduced. Accordingly, leakage currents between adjacent interconnections can be reduced. In addition, by performing the plasma process twice, the metal oxide layer can be deoxidized so that the damage to the insulating layer is minimized. Therefore, the reliability of the semiconductor integrated circuit device can be improved. 
   Hereinafter, a semiconductor integrated circuit device according to an embodiment of the present invention will be described with reference to  FIG. 9 . Referring to  FIG. 9 , the semiconductor integrated circuit device according to an embodiment of the present invention includes a semiconductor substrate  100 , an insulating layer  110   b  formed on the semiconductor substrate  100  and including a lower region  112  and an upper region  111  having a carbon content lower than that of the lower region  112  and having a thickness in the range of 50 to 500 Å. A damascene interconnection  130  is formed in the insulating layer  110   b , and a barrier layer  160  formed on the damascene interconnection  130  and the insulating layer  110   b . The insulating layer  111   b  may be divided into the upper region  111  and the lower region  112 . As described above, the upper region  111  is a region from which carbon is removed by the first plasma process, and thus has a low carbon content and a high porosity in comparison to the lower region  112 . 
   In the case where the first plasma process is performed under a weaker condition, the upper region  111  is formed to a thickness of about 50 to 500 Å. Accordingly, the thickness of the upper region  111  is reduced in comparison to the case that the entire metal oxide layer is removed by performing the first plasma process only, and thus the reliability of the device is further improved. 
   The barrier layer  160  includes the first barrier layer  161   a  and the second barrier layer  162 , which are separately formed. Specifically, since the second plasma process for removing the metal oxide layer is performed after the first barrier layer  161   a  is formed, a discontinuous surface may exist between the first barrier layer  161   a  and the second barrier layer  162 . In this case, the first barrier layer  161   a  and the second barrier layer  162  may be formed of substantially the same material. 
   Hereinafter, a method of fabricating a semiconductor integrated circuit device according to another embodiment of the present invention will be described with reference to  FIGS. 10 to 13 .  FIG. 10  is a flowchart illustrating a method of fabricating a semiconductor integrated circuit device according to another embodiment of the present invention, and  FIGS. 11 to 13  are sectional views successively explaining the method of fabricating a semiconductor integrated circuit device of  FIG. 10 . In the following description of the present invention, the same drawing reference numerals are used for the same elements as illustrated in  FIGS. 1 to 9 , and the detailed description of the corresponding components has been omitted. 
   According to the method of fabricating a semiconductor integrated circuit device according to another embodiment of the present invention, the first barrier layer is formed without performing the first plasma process, unlike the method according to the embodiment of the present invention described by  FIGS. 1-9 . Since the steps performed before Step S 250  are the same as those in an embodiment of the present invention, only the subsequent steps will be described. 
   Referring to  FIGS. 10 and 11 , an insulating layer  110   a  is formed on a semiconductor substrate  100  (Step S 110 ). A recess  120  is formed on the insulating layer (Step S 120 ) and then a damascene interconnection layer  130   a  is formed so as to completely fill in the recess (Step S 130 ). Then, a damascene interconnection  130  is formed by performing a smoothing process (Step S 140 ) and a first barrier layer  161   a  is formed on the damascene interconnection  130  and the insulating layer  110   a  (Step S 250 ). 
   Specifically, the first barrier layer  161   a  is thinly deposited on the insulating layer  110   a  in which the damascene interconnection  130  and the metal oxide layer  140  are formed. At this time, the first barrier layer  161   a  may be formed by CVD or PECVD. The first barrier layer  161   a  may be formed, for example, of silicon nitride (SiN), silicon carbide (SiC), or silicon carbon nitride (SiCN). The first barrier layer  161   a  may serve to provide electrical insulation to the damascene interconnection  130 , or serve as a stopper in the etching process for forming another damascene interconnection (not illustrated). 
   The first barrier layer  161   a  has a thickness E sufficient to prevent the insulating layer  110   b  from being damaged due to the plasma process, and to allow ions and radicals (e.g., hydrogen radicals) to pass through the first barrier layer  161   a  during the plasma process. The thickness E of the first barrier layer  161   a  may be in the range of about 5 to 50 Å, and be preferably about 20 Å. 
   Then, as shown in  FIGS. 10 and 12 , the plasma process is performed (Step S 260 ). The semiconductor substrate  100 , on which the first barrier layer  161  is formed, is put in a plasma processing device (not illustrated), and a plasma process  270  is performed, for example, by injecting a gas including hydrogen. Hydrogen ions and hydrogen radicals created by the plasma process  270  pass through the first barrier layer  161   a , and deoxidize a metal oxide layer  142  formed on an upper part of the damascene interconnection  130 . At this time, H2O, which is a by-product of the interaction between hydrogen and the metal oxide in the metal oxide layer  142 , is discharged out of the first barrier layer  161   a . The plasma process is performed for a sufficient time, and thus the metal oxide layer  142  may be completely removed (i.e., completely deoxidized). 
   Then, as shown in  FIGS. 10 and 13 , a second barrier layer  162  is formed on the first barrier layer  161   a  (Step S 250 ). The second barrier layer  162  may be made of substantially the same material as the first barrier layer  161   a . Also, the second barrier layer  162  may be formed by CVD or PECVD in the same manner as the first barrier layer  161   a.    
   In this case, if the thickness D of the barrier layer  160  including the first barrier layer  161   a  and the second barrier layer  162  is not sufficient, oxygen may pass through the barrier layer  160  and a metal oxide layer may be formed again on the damascene interconnection  130 . Accordingly, the thickness D of the barrier layer  160  should be about 250 Å or more. Thus, the second barrier layer  162  and the first barrier layer  161   a  are formed to a combined thickness of about 250 Å or more. 
   According to the method of fabricating a semiconductor integrated circuit device according to another embodiment of the present invention, the plasma process is formed after the damascene interconnection is formed and the first barrier layer is deposited, and the first barrier layer protects the insulating layer during the plasma process. That is, the first barrier layer inhibits the damage of the insulating layer due to the plasma by intercepting the direct contact of the plasma with the insulating layer, and thus the reliability of the semiconductor integrated circuit device is improved. 
   Thus, the semiconductor integrated circuit device of  FIG. 13  includes a semiconductor substrate  100 , an insulating layer  110   a  formed on the semiconductor substrate  100 , a damascene interconnection  130  formed in the insulating layer  110   a , a first barrier layer  161   a  formed on the damascene interconnection  130  and the insulating layer  110   a , and a second barrier layer  162  discontinuously formed on the first barrier layer  161   a  using the same material as the first barrier layer  161   a . The first barrier layer  161   a  is formed to a thickness of about 5 to 50 Å. Since the plasma process is performed after the first barrier layer  161   a  is formed, a discontinuous surface may exist between the first barrier layer  161   a  and the second barrier layer  162 . In this case, the first barrier layer  161   a  and the second barrier layer  162  may be formed of substantially the same material. For example, the first barrier layer  161   a  and the second barrier layer may be formed of silicon nitride (SiN), silicon carbide (SiC), or silicon carbon nitride (SiCN). 
   Although preferred embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.