Semiconductor device and method of producing the same

DETAILED DESCRIPTION OF THE INVENTION (First Embodiment) Referring to FIG.
1(a) to FIG.
1(d), the following description will discuss a semiconductor device according to a first embodiment of the present invention, and a method of producing the same.
As shown in FIG.
1(a), a first silicon oxide layer 21 having a thickness of 500 nm for example is deposited, by a CVD method, on a semiconductor substrate 20 made of silicon for example, and a porous layer 22 having a thickness of 400 nm for example is deposited on the first silicon oxide layer 21.
Then, a resist pattern is formed on the porous layer 22, and using the resist pattern as a mask, the porous layer 22 is etched to form a wiring groove 22a in the porous layer 22.
As shown in FIG.
1(b), a second silicon oxide layer 23 having a thickness of 20 nm for example is deposited throughout the surface of the porous layer 22 by a CVD method.
As shown in FIG.
1(c), a resist pattern is formed on the second silicon oxide layer 23, and using the resist pattern as a mask, the first and second silicon oxide layers 21, 23 are etched to form a through-hole 21a in the first and second silicon oxide layers 21, 23.
As shown in FIG.
1(d), a conductive layer 24 is deposited throughout the surface of the substrate and those portions of the conductive layer 24 exposed onto the second silicon oxide layer 23 are subjected to CMP, thus forming a wiring layer made of the conductive layer 24.
According to the first embodiment, the second silicon oxide layer 23 is deposited on the surface of the wiring groove 22a in the porous layer 22.
Therefore, the conductive material forming the conductive layer does not enter holes in the porous layer 22.
This not only prevents the porous layer 22 from being deteriorated in insulating properties, but also prevents the wiring layer from being deteriorated in resistance to electromigration.
(Second Embodiment) The following description will discuss a semiconductor device according to a second embodiment of the present invention and a method of producing the same