Liquid crystal display having aluminum wiring

1. A liquid crystal display comprising:

a liquid crystal display substrate;

a main wiring layer made of Al or Al alloy and formed on said substrate; and

a protective layer containing refractory metal and formed on the main wiring layer,

wherein an upper surface of said main wiring layer has an average roughness of 3 nm or larger.

2. The liquid crystal display according to claim 1 , wherein said main wiring layer forms gate wiring lines and storage capacitor wiring lines, and the liquid crystal display further comprises:

a gate insulating film covering said protective layer;

a semiconductor layer formed on said gate insulating film;

an insulating layer covering a region above said semiconductor layer; and

pixel electrodes formed on said insulating layer.

3. The liquid crystal display according to claim 1 , further comprising:

an opposing substrate; and

a liquid crystal layer sandwiched between said liquid crystal display substrate and said opposing substrate.

4. The liquid crystal display according to claim 1 , wherein said main wiring layer includes grains without whiskers.

5. The liquid crystal display according to claim 1 , wherein said protective layer is a two layer structure that includes a refractory metal layer formed upon a refractory metal nitride layer.

6. The liquid crystal display according to claim 5 , wherein said refractory metal nitride layer is composed of Mo nitride and said refractory metal layer is composed of Mo.

7. The liquid crystal display according to claim 5 wherein said refractory metal nitride layer is of a thickness of approximately 100 nm and said refractory metal layer is of a thickness of approximately 10 nm.