Method of forming pad and fuse in semiconductor device

1. A method of forming a pad and a fuse in a semiconductor device, the method comprising:

forming first, second and third copper layers in a dielectric layer, the first copper layer being located in a pad region, the second and third copper layers being located in a fuse region, wherein the first, second and third copper layers are respectively connected to metal lines provided on a semiconductor substrate;

forming a first insulating layer on the dielectric layer to cover the copper layers;

selectively etching the first insulating layer to expose the second and third copper layers in the fuse region;

forming a fuse pattern including first and second aluminum fuses on the first insulating layer in the fuse region,

wherein the first aluminum fuse is connected to the exposed second copper layer, the second aluminum fuse is connected to the exposed third copper layer, and the first and second aluminum fuses are disconnected from each other mutually;

forming a second insulating layer on the first and second aluminum fuses and the first insulating layer;

selectively etching the first and second insulating layers to expose the underlying first copper layer in the pad region;

forming an aluminum pad on the second insulating layer in the pad region, the aluminum pad being connected to the exposed first copper layer in the pad region;

forming at least one third insulating layer on both the aluminum pad and the second insulating layer;

forming a photoresist pattern on the third insulating layer, the photoresist pattern being formed to define a pad opening in the pad region and a fuse opening in the fuse region; and

forming the pad and fuse openings by selectively etching the third insulating layer using the photoresist pattern, wherein

the aluminum pad is exposed through the pad opening; and

the first and second aluminum fuses are unexposed through the fuse opening.

2. The method of claim 1 , wherein the third insulating layer includes a third insulating layer, a fourth insulating layer and a fifth insulating layer.

3. The method of claim 1 , wherein the second and third copper layers respectively comprise disconnected separate patterns in the fuse region.

4. The method of claim 1 , wherein the second insulating layer is eight to ten times as thick as the third insulating layer.

5. The method of claim 1 , wherein the thickness of the second insulating layer is 700˜1000 Å.

6. The method of claim 1 , wherein an upper surface of the aluminum pad on the first copper layer in the pad region and an upper surface of the first and second aluminum fuses on the second and third copper layers in the fuse region are on different horizontal planes.

7. The method of claim 1 , wherein the pad opening and the fuse opening are formed simultaneously.

8. The method of claim 1 , wherein the step of forming the aluminum pad is performed after the step of forming the first and second aluminum fuses.

9. The method of claim 2 , wherein the third, the fourth and the fifth insulating layers are made of silicon nitride, silicon oxide and silicon nitride, respectively.

10. The method of claim 9 , wherein the etching of the fourth insulating layer use an etchant gas with a high selectivity of oxide-to-nitride.