Semiconductor device and manufacturing method thereof

1. A semiconductor device comprising:

a substrate;

a semiconductor chip provided on the substrate;

a resin covering the semiconductor chip; and

a metal film provided on the resin, wherein

the metal film includes a first metal layer provided on the resin, a second metal layer provided on the first metal layer, and a third metal layer provided on the second metal layer, and

the first metal layer and the second metal layer contain a same material, and a particle diameter of the second metal layer is smaller than a particle diameter of the first metal layer,

wherein the particle diameter of the first metal layer of at least 0.20 μm and no more than 0.5 μm, and the particle diameter of the second metal layer is 0.15 μm or less.

2. The semiconductor device according to claim 1 , wherein

the first metal layer and the second metal layer contain copper.

3. The semiconductor device according to claim 1 , wherein

the first metal layer has a film thickness of at least 1.5 μm and no more than 2.5 μm, and the second metal layer has a film thickness of at least 0.3 μm and no more than 1.5 μm.

4. The semiconductor device according to claim 1 , wherein

the first metal layer contains copper with a purity of 99.99% or more, and the second metal layer contains copper with a purity of less than 99.99%.

5. The semiconductor device according to claim 1 , wherein

the resistance of the first metal layer is less than 2.0 μΩ·cm.

6. The semiconductor device of claim 1 , wherein a resistance of the second metal layer is higher than a resistance of the first metal layer.

7. The semiconductor device of claim 1 , wherein the metal film further includes a fourth metal layer containing at least one of stainless steel, nickel and titanium.