Method of manufacturing semiconductor device having pad region for wire-bonding

1. A method of manufacturing a semiconductor device, comprising:

providing an insulating film on a surface of a semiconductor substrate;

forming a porous metal film on a region of the insulating film, the porous metal film containing numerous voids;

providing a protective film on the porous metal film;

providing an opening portion in the protective film on the porous metal film, the opening portion defining a pad region; and

wire-bonding a wire to the porous metal film in the pad region;

wherein the forming of the porous metal film comprises:

forming a first metal film on the insulating film;

forming a trench in the first metal film;

forming a second metal film by sputtering on the first metal film including the trench; and

filling the second metal film containing the voids in the trench.

2. A method of manufacturing a semiconductor device according to claim 1 , wherein the forming of the porous metal film comprises forming a metal film under a state in which an angle between a target used in sputtering and a semiconductor substrate is set to 30° to 80°, and a gas pressure of an argon gas used in the sputtering is set to 2 Pa to 3 Pa.

3. A method of manufacturing a semiconductor device, comprising:

providing an insulating film on a surface of a semiconductor substrate;

forming a porous metal film on a region of the insulating film, the porous metal film containing numerous voids;

providing a protective film on the porous metal film;

providing an opening portion in the protective film on the porous metal film, the opening portion defining a pad region; and

wire-bonding a wire to the porous metal film in the pad region;

wherein the forming of the porous metal film comprises forming the porous metal film having a void region containing the numerous voids and a void-free region that does not contain any voids; and wherein during the providing of the opening portion in the protective film on the porous metal film the opening portion defines the pad region having a pad opening end, and an interface between the void region and the void-free region of the porous metal film is disposed at one of the pad opening end and a position outside of the pad opening end.

4. A method of manufacturing a semiconductor device, comprising:

providing an insulating film on a surface of a semiconductor substrate;

forming a first metal film on the insulating film;

forming a trench in the first metal film;

filling a second metal film containing numerous voids in the trench to form a porous metal film;

providing a protective film on the porous metal film;

forming an opening portion in the protective film to defining a pad region; and

wire-bonding a wire to the porous metal film in the pad region.

5. A method of manufacturing a semiconductor device according to claim 4 ; wherein during the wire-bonding of the wire, the voids in the porous metal film are crushed due to the impact of the wire-bonding thereby absorbing stress generated by the impact and avoiding generation of cracks in the insulating film.

6. A method of manufacturing a semiconductor device according to claim 4 ; wherein during the filling of the second metal film, the porous metal film is formed with a void region containing the numerous voids and a void-free region that does not contain any voids; and wherein during the forming of the opening portion in the protective film the pad region defined with a pad opening end, and an interface between the void region and the void-free region of the porous metal film is disposed at one of the pad opening end and a position outside of the pad opening end.

7. A method of manufacturing a semiconductor device, comprising:

providing an insulating film on a surface of a semiconductor substrate;

forming on the insulating film a porous metal film containing numerous voids;

providing a protective film on the porous metal film;

forming in the protective film an opening portion defining a pad region; and

wire-bonding a wire to the porous metal film in the pad region so that the voids in the porous metal film are crushed due to an impact of the wire-bonding on the pad region thereby absorbing stress generated by the impact and avoiding generation of cracks in the insulating film.