Abstract:
The present invention is related to a method for forming a hydrogen barrier layer capable of protecting a bottom structure from damages occurring due to hydrogen produced during a semiconductor device fabrication. The method includes the steps of: forming a hafnium vanadium oxide (HfVO x ) layer on a substrate structure providing a predetermined semiconductor device structure, the HfVO x  layer being used as a hydrogen diffusion barrier layer; and forming an insulation layer on the HfVO x  layer.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a method for fabricating a semiconductor device; and, more particularly, to a method for forming a hydrogen diffusion barrier layer in a semiconductor device. 
     DESCRIPTION OF RELATED ARTS 
     In a semiconductor device, an insulation layer for insulating a bottom structure and a top structure can be classified into an inter-layer insulation layer, an inter-metal insulation layer and a passivation layer. 
     In an insulation layer formation process, plasma and source gas including hydrogen are typically used. Thus, hydrogen atoms, ions and molecules are diffused into a previously formed bottom structure, particularly into a dielectric thin layer of a capacitor, and this diffusion results in degradation of dielectric material properties. Accordingly, a diffusion barrier layer against hydrogen produced when forming an insulation layer is formed prior to forming the insulation layer. 
     FIG. 1 is a cross-sectional view showing a conventional method for fabricating a semiconductor device. 
     As shown, a first inter-layer insulation layer  4  is formed on a substrate  22  providing a first and a second active regions  2 A and  2 B, a device isolation layer  1  and a gate pattern  3 . Then, the first inter-layer insulation layer  4  is selectively removed to form a bit line  5  connected to the second active region  2 B formed on one side of the gate pattern  3 . 
     A second inter-layer insulation layer  6  is formed on the first inter-layer insulation layer  4 , and an insulation layer  7  for passivation is formed thereon. 
     Subsequent to the second inter-layer insulation layer  6  formation, an adhesion layer  8  for adhering a lower electrode  9  to the second inter-layer insulation layer  6  is formed on a region where a capacitor will be formed. On top of the adhesion layer  8 , the capacitor including the lower electrode  9 , a dielectric thin layer  10  and an upper electrode  11  is formed. After forming the capacitor, a first diffusion barrier layer  12  for preventing diffusions of hydrogen produced during a subsequent insulation layer formation process is formed in such a manner that it encompasses the capacitor. 
     Next, a third inter-layer insulation layer  13  is formed, and a contact hole exposing the upper electrode  11  and another contact hole exposing the first active region  2 A formed on the other side of the gate pattern  3  are formed thereafter. 
     Afterwards, a ferroelectric passivation layer  14  for protecting the upper electrode  11  of the capacitor and a barrier metal layer  15  are formed. A first metal line  16  connecting the upper electrode  11  to the first active region  2 A is formed thereon. A second diffusion barrier layer  17  for preventing diffusions of hydrogen is formed on an entire surface of the substrate  22  so as to encompass the previously formed structure. 
     A third diffusion barrier layer  18  is formed on the second diffusion barrier layer  17 , and a second metal line  19  is formed thereon. On top of the second metal line  19 , a forth diffusion barrier layer  20  and a passivation layer  21  are sequentially formed. 
     The above first to third diffusion barrier layers  12 ,  17  and  20  are the diffusion barrier layer against hydrogen and usually use Al 2 O 3  or TiO 2  insulation layer. However, this type of insulation layer cannot completely prevent the hydrogen diffusion. 
     Also, hydrogen in an atom, molecule or plasma state used during the insulation formation process shocks the bottom structure, and this shock effect becomes a critical factor affecting a functional decrease of a semiconductor device. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to provide a hydrogen diffusion barrier layer capable of preventing a bottom structure from damage occurring due to hydrogen produced during a semiconductor device fabrication process. 
     In accordance with an aspect of the present invention, there is provided a method for fabricating a semiconductor device including the steps of: forming a hafnium vanadium oxide (HfVO x ) layer on a substrate providing a predetermined structure, the HfVO x  layer being used as a hydrogen diffusion barrier layer; and forming an insulation layer on the HfVO x  layer. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING(S) 
     The above and other objects and features of the present invention will become apparent from the following description of the preferred embodiments given in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a cross-sectional view showing a conventional method for fabricating a semiconductor device; and 
     FIG. 2 is a cross-sectional view showing a method for forming a capacitor of a semiconductor device in accordance with a preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 2 is a cross-sectional view showing a method for forming a capacitor of a semiconductor device in accordance with a preferred embodiment of the present invention. 
     Referring to FIG. 2, a first inter-layer insulation layer  34  is formed on a substrate  30  providing a first and a second active regions  32 A and  32 B, a device isolation layer  31  and a gate pattern  33 . Then, the first inter-layer insulation layer  34  is selectively removed to form a bit line  35  connected to the second active region  32 B formed on one side of the gate pattern  33 . 
     A second inter-layer insulation layer  36  is formed on the first inter-layer insulation layer  34 , and a passivation layer  37  is formed thereon by using silicon oxide. 
     Subsequent to the passivation layer  37  formation, an adhesion layer  38  for adhering a lower electrode  39  to the second inter-layer insulation layer  36  is formed on a region where a capacitor will be formed. On top of the adhesion layer  38 , the capacitor including the lower electrode  39 , a dielectric thin layer  40  and an upper electrode  41  is formed. After forming the capacitor, a first diffusion barrier layer  42  for preventing diffusions of hydrogen produced during a subsequent insulation layer formation process is formed in such a manner that it encompasses the capacitor. 
     Herein, the first diffusion barrier layer  42  uses a hafnium vanadium oxide (HfVO x ) layer and is deposited through the use of a physical vapor deposition (CVD) technique. The HfVO x  layer is a highly densified layer formed by adding vanadium to a basis material, hafnium oxide, which is denser than alumina and titanium oxide. 
     As well known, hydrogen has a very high diffusion rate. Thus, it is necessary to have a micronized structure, which is dense, and a capability to store hydrogen in order to suppress diffusions of hydrogen. The HfVO x  layer has an excellent property of suppressing the hydrogen diffusion because it is capable of storing hydrogen at a relatively high temperature, e.g., at about 500° C. 
     Next, a third inter-layer insulation layer  43  is formed, and a contact hole exposing the upper electrode  41  and another contact hole exposing the first active region  32 A formed on the other side of the gate pattern  33  are formed. 
     Afterwards, a ferroelectric passivation layer  44  for protecting the upper electrode  41  of the capacitor and a barrier metal layer  45  are formed. A first metal line  46  connecting the upper electrode  41  to the first active region  32 A is formed thereon. A second diffusion barrier layer  47  for preventing the hydrogen diffusion is formed on an entire surface of the substrate  30  so as to encompass the previously formed structure. 
     A third diffusion barrier layer  48  is formed on the second diffusion barrier layer  47 , and a second metal line  49  is formed thereon. On top of the second metal line  49 , a forth diffusion barrier layer  50  and a passivation layer  51  are sequentially formed. 
     In accordance with the preferred embodiment of the present invention, it is possible to form a hydrogen diffusion barrier layer capable of effectively preventing diffusions of hydrogen produced during an insulation layer formation process after forming a capacitor. As a result of this effective prevention of the hydrogen diffusion, reliability and electric properties of a semiconductor device have been improved. 
     A deposition process and a densification process of the HfVO x  layer used as the hydrogen diffusion barrier layer will be explained in more detail in the following. 
     The HfVO x  layer is deposited through a PVD technique carried out at a temperature ranging from about 100° C. to about 900° C. by using a reaction gas produced from the reaction between Hf and V targets. The deposition thickness ranges from about 200 Å to about 1000 Å. Also, the Hf, V and O have composition ratios of about 50 to 90 at %, about 10 to 50 at % and about 1 to 80 at %, respectively. 
     In order to densify the HfVO x  layer, oxygen can be additionally filled up. At this time, the oxygen filling-up procedure is proceeded through a rapid thermal annealing process carried out at a temperature ranging from about 100° C. to about 650° C. for about 1 to 5 minutes in an atmosphere of oxygen. 
     Also, it is still possible to carry out a rapid thermal annealing process at a temperature ranging from about 100° C. to about 650° C. for about 1 to 5 minutes in an atmosphere of Ar and O 2  or N 2  and O 2 . 
     In order to densify the diffusion barrier layer and obtain a uniform surface filling-up of the diffusion barrier layer, it is further possible to use ionized oxygen, which is accelerated at the same temperature above for about 1 to 5 minutes by an electric field generated around the substrate  30 . 
     In addition, Ar presents within a chamber is ionized or Ar and oxygen are simultaneously ionized and this ionized Ar or Ar and Oxygen gets to hit the deposited diffusion barrier layer for densification. Afterwards, a uniform oxide layer is formed with use of oxygen ions. At this time, this process is proceeded also at a temperature of about 100° C. to about 650° C. for about 1 to 5 minutes. 
     It is also possible to ionize nitrogen within a chamber or ionize nitrogen and oxygen simultaneously, and then, this ionized nitrogen or nitrogen and oxygen gets to hit the diffusion barrier layer for densification. Thereafter, oxygen ions are used to form a uniform oxide layer. Also, this process is carried out under the same condition of the above temperature and duration time. 
     It is further possible to perform a heat treatment with NH 4  or with NH 4  plasma so that a uniform oxide layer is formed under the same condition of the above temperature and duration time. 
     NH 4  plasma, Oxygen plasma or UV ozone can be used in addition to the aforementioned ones. Furthermore, it is possible to reform the surface of the diffusion barrier layer through combinations of the above methods. 
     By following the preferred embodiment of the present invention, there is provided an effect of improving reliability by preventing hydrogen diffusions into a bottom structure during a semiconductor device fabrication process. 
     While the present invention has been described with respect to certain preferred embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.