Pad metallization with oxide layer to reduce deformation of conductive films

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

(a) forming a multilayer wiring layer on a semiconductor substrate;

(b) forming a dielectric film so as to cover a pad electrode formed in an uppermost wiring layer of the multilayer wiring layer;

(c) forming an opening portion in the dielectric film so as to reach the pad electrode;

(d) forming a first conductive film on the pad electrode in the opening portion by a plating method;

(f) after the (d), forming a second conductive film on the first conductive film by a plating method;

(g) after the (f), forming a third conductive film on the second conductive film by a plating method; and

(e) after the (g), performing an oxidation treatment to the first conductive film and oxidizing a material contained in the first conductive film, thereby forming an oxide layer on a side surface of the first conductive film,

wherein a width of the oxide layer is 200 nm or more,

wherein Vickers hardness of the third conductive film is smaller than Vickers hardness of each of the first conductive film and the second conductive film, and

wherein a thickness of the third conductive film is thicker than a thickness of each of the first conductive film and the second conductive film.

2 . The method according to claim 1 ,

wherein the material contained in the first conductive film is copper, and

wherein the oxide layer is copper oxide.

3 . The method according to claim 2 ,

wherein the oxidation treatment is a heat treatment performed in an oxygen atmosphere and under conditions of 100° C. or higher and 450° C. or lower, or is an oxygen plasma treatment performed under conditions of 100° C. or higher and 250° C. or lower.

4 . The method according to claim 1 ,

wherein in the (c), the first conductive film is formed on the dielectric film, and

wherein the oxide layer is in contact with the dielectric film.

5 . The method according to claim 1 ,

wherein the material contained in the first conductive film is copper,

wherein a material contained in the second conductive film is nickel,

wherein a material contained in the third conductive film is gold, and

wherein the oxide layer is copper oxide.

6 . The method according to claim 1 , comprising:

(h) after the (e), connecting a wire bonding to the third conductive film.

7 . The method according to claim 1 ,

(i) after the (d) and before the (e), forming a second conductive film on the first conductive film by a plating method;

(j) after the (i) and before the (e), forming a first solder layer on the second conductive film;

(k) preparing a mounting substrate having a first wiring and a second solder layer formed on the first wiring; and

(l) after the (j) and the (k) and before the (e), bonding the first solder layer with the second solder layer.

8 . The method according to claim 7 ,

wherein the material contained in the first conductive film is copper,

wherein the oxide layer is copper oxide, and

wherein the oxidation treatment is a heat treatment performed in an oxygen atmosphere and under conditions of 100° C. or higher and 200° C. or lower, or is an oxygen plasma treatment performed under conditions of 100° C. or higher and 200° C. or lower.

9 . The method according to claim 1 ,

wherein a side surface of the oxide layer is retracted from a side surface of each of the second conductive film and the third conductive film.

10 . The method according to claim 1 , comprising:

(m) forming a barrier metal film on the dielectric film and in the opening portion,

wherein the oxide layer covers a side surface of the barrier metal film and is in contact with the dielectric film.