The present application claims priority to Korean patent application number 10-2007-065015, filed on Jun. 29, 2007, which is incorporated by reference in its entirety.
The present invention relates to a semiconductor device and, more particularly, to a method of forming a contact plug with improved contact resistance and process steps.
In a process of forming contact plugs connecting lower metal lines made of a metal layer (in particular, a copper (Cu) layer) and an upper metal line made of a metal layer (in particular, an aluminum (Al) layer), if a barrier metal layer having a stack structure of a tantalum (Ta) layer and a tantalum nitride (TaN) layer is formed within the contact plugs, there is a high probability that cracks can occur in the barrier metal layer due to high stress.
Further, in the case where nitrogen (N2) is flown in order to form a barrier metal layer on a surface of a contact hole when lower metal lines is opened using an etch process for forming the contact hole, a copper (Cu) layer (that is, the material of the lower metal lines) is combined with nitrogen (N2), resulting in the formation of a Cu—N material having an insulating characteristic at the bottom of the contact hole. Accordingly, resistance fail occurs.
The present invention is directed towards the improved characteristic of a barrier metal layer with respect to lower metal lines made of a copper (Cu) layer by forming the barrier metal layer using a hybrid scheme, including a process of stuffing oxygen (O2) atoms, after a stack structure of a tungsten (W) layer and a tungsten nitride (WN) layer is formed within a contact hole.
According to a method of fabricating a semiconductor device in accordance with an embodiment the present invention, an insulating layer in which contact holes are formed is formed over a semiconductor substrate in which lower metal lines are formed. A barrier metal layer, having a stack structure of a first tungsten (W) layer and a tungsten nitride (WN) layer, is formed within the contact holes. Contact plugs are formed within the contact holes.
The lower metal lines may be made of a copper (Cu) layer. A pre-cleaning process may be further performed after the contact holes are formed. The pre-cleaning process may be performed using a mixed gas of SiH4 and H2 gases and a plasma.
At the time of the formation process of the barrier metal layer, a second tungsten (W) layer may be further formed on the tungsten nitride (WN) layer. Each of the first tungsten (W) layer and the second tungsten (W) layer may be formed to a thickness of 20 to 200 angstrom. The tungsten nitride (WN) layer may be formed to a thickness of 100 to 1000 angstrom. The tungsten nitride (WN) layer may be formed in the same chamber as that in which the first tungsten (W) layer or the tungsten (W) layer is formed. The tungsten nitride (WN) layer may be formed on the first tungsten (W) by flowing an N2 or NH3 gas.
A process of stuffing the barrier metal layer with oxygen (O2) atoms may be further performed after the barrier metal layer is formed. The stuffing process may be performed using an anneal or plasma process. The pre-cleaning process and the process of forming the barrier metal layer may be performed in-situ within one chamber. The contact plugs may be made of a tungsten (W) layer.
According to a method of fabricating a semiconductor device in accordance with another embodiment the present invention, a first insulating layer in which lower metal lines are formed is formed over a semiconductor substrate. A second insulating layer in which contact holes are formed is formed over the first insulating layer and lower metal lines. A barrier metal layer is formed within the contact holes. A process of stuffing the barrier metal layer with oxygen (O2) atoms is performed. Contact plugs are formed by gap filling the contact holes with a conductive layer. Upper metal lines are formed on the contact plugs.
The lower metal lines may be made of a copper (Cu) layer. A pre-cleaning process may be further performed after the contact holes are formed. The pre-cleaning process may be performed using a mixed gas of SiH4 and H2 gases and a plasma.
The barrier metal layer may have a stack structure of a tungsten (W) layer and a tungsten nitride (WN) layer. The barrier metal layer may have a stack structure of a first tungsten (W) layer, a tungsten nitride (WN) layer and a second tungsten (W) layer. The tungsten (W) layer may be formed to a thickness of 20 to 200 angstrom. Each of the first tungsten (W) layer and the second tungsten (W) layer may be formed to a thickness of 20 to 200 angstrom. The tungsten nitride (WN) layer may be formed to a thickness of 100 to 1000 angstrom. The tungsten nitride (WN) layer may be formed in the same chamber as that in which the first tungsten (W) layer or the tungsten (W) layer is formed. The tungsten nitride (WN) layer may be formed on the first tungsten (W) by flowing an N2 or NH3 gas.
After the barrier metal layer is formed, a process of stuffing the barrier metal layer with oxygen (O2) atoms may be further performed. The stuffing process may be performed using an anneal or plasma process. The pre-cleaning process and the process of forming the barrier metal layer may be performed in-situ within one chamber. The contact plugs may be made of a tungsten (W) layer. The upper metal lines may be made of an aluminum (Al) layer.
A semiconductor device according to still another embodiment the present invention includes lower metal lines formed over a semiconductor substrate, an insulating layer including contact holes through which the lower metal lines are exposed over the semiconductor substrate including the lower metal lines, a barrier metal layer formed on sidewalls of the contact holes and the lower metal lines and including a first tungsten (W) layer and a tungsten nitride (WN) layer, and contact plugs formed on the barrier metal layer within the contact holes.
The lower metal lines may be made of a copper (Cu) layer. The insulating layer may be made of oxide. The barrier metal layer may further include a second tungsten (W) layer on the tungsten nitride (WN) layer. The first tungsten (W) layer may be formed to a thickness of 20 to 200 angstrom. The tungsten nitride (WN) layer may be formed to a thickness of 100 to 1000 angstrom. The second tungsten (W) layer may be formed to a thickness of 20 to 200 angstrom. The contact plugs may be made of a tungsten (W) layer.
Specific embodiments according to the present invention will be described with reference to the accompanying drawings.
Referring to
A damsacene pattern is formed within the first insulating layer 102 using a damascene process. The damsacene pattern is gap filled with a first conductive layer, thus forming lower metal lines 104. The first conductive layer may be made of a copper (Cu) layer.
A second insulating layer 106 is formed over the first insulating layer 102 and the lower metal lines 104. Contact holes 108 are formed by etching the second insulating layer 106 until the lower metal lines 104 are exposed using an etch process. The second insulating layer 106 may be made of oxide.
A pre-cleaning process is performed in order to minimize the loss of the lower metal lines 104. The pre-cleaning process may be performed using a mixed gas of SiH4 and H2 and a plasma in order to remove native oxide and polymer generated at the time of an etch process.
Referring to
The method of forming the barrier metal layer 110 using the hybrid scheme including the process of oxygen (O2) stuffing, after the stack structure of the tungsten (W) layer and the tungsten nitride (WN) layer is formed, is described in more detail below.
The tungsten (W) layer (as the barrier metal layer 110) is formed on a surface of the second insulating layer 106 and the contact holes 108. The tungsten (W) layer may be formed to a thickness of 20 to 200 angstrom. If the tungsten (W) layer is formed on the surface of the second insulating layer 106 and the contact holes 108 as described above, an adhesive characteristic with the contact resistance Rc can be improved.
The tungsten nitride (WN) layer is formed on the tungsten (W) layer by flowing N2 or NH3 gases into the same chamber as that in which the tungsten (W) layer has been formed. The tungsten nitride (WN) layer may be formed to a thickness of 100 to 1000 angstrom.
In order to fill the grain boundary portion of the barrier metal layer 110 (that is, the tungsten nitride (WN) layer) with oxygen (O2) atoms, an anneal or plasma process is performed on the result in which the barrier metal layer 110 is formed. The anneal process is carried out within a furnace. The purpose of stuffing the grain boundary portion of the tungsten nitride (WN) layer with oxygen (O2) atoms is to prohibit aluminum atoms of an aluminum (Al) layer, formed in a subsequent process, from being infiltrated into an active region through the tungsten nitride (WN) layer by enhancing the characteristic of the barrier metal layer 110 (that is, the tungsten nitride (WN) layer).
The pre-cleaning process and the formation process of the barrier metal layer 110 are formed in-situ within one chamber. If the barrier metal layer 110 has a stack structure including the tungsten (W) layer and the tungsten nitride (WN) layer as described above, a resistivity characteristic of about 4.4 μΩ×cm can be obtained.
Referring to
Referring to
As described above, after the stack structure including the tungsten (W) layer and the tungsten nitride (WN) layer is formed within the contact holes, the barrier metal layer is formed using a hybrid scheme including the process of oxygen (O2) stuffing. Accordingly, the characteristic of the barrier metal layer with respect to the lower metal lines made of the copper (Cu) layer can be improved.
Further, since the barrier metal layer is made of the tungsten (W) layer, a nucleation process can be omitted at the time of the tungsten (W) layer formation process for forming the contact plugs. Accordingly, the process can be simplified and therefore the contact resistance Rc can be improved.
Moreover, since a nucleation process is omitted, the contact resistance Rc can be improved.
In addition, since the tungsten (W) layer is formed on a surface of the contact holes, the contact resistance Rc and adhesive characteristic can be improved.
Incidentally, since the pre-cleaning process and the barrier metal layer (110) formation process are performed in-situ within one chamber, the process steps can be simplified.
The present invention is not limited to the disclosed embodiments, but may be implemented in various manners. The embodiments are provided to complete the disclosure of the present invention and to allow those having ordinary skill in the art to understand the scope of the present invention. The present invention is defined by the category of the claims.
Number | Date | Country | Kind |
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10-2007-0065015 | Jun 2007 | KR | national |