Mask and method of manufacturing liquid crystal display device using the same

1. A method of manufacturing a liquid crystal display device, comprising:

forming a gate electrode in a pixel unit and a pad in a pad unit on a first substrate;

depositing a gate insulating layer, a semiconductor layer, a metal layer, and a passivation layer over the first substrate;

depositing a photoresist layer over the passivation layer;

irradiating light onto the first substrate through a mask having a transmissive region, a half-transmissive region, a diffractive region and an interceptive region and developing the photoresist layer to form a photoresist pattern having at least three different thicknesses;

first etching the gate insulating layer, the semiconductor layer, the metal layer, and the passivation layer over the pad to open the pad;

first ashing the photoresist pattern and second etching the passivation layer and metal layer in the pad and pixel units;

second ashing the photoresist pattern and third etching the passivation layer over the gate electrode;

fourth etching the metal layer and a part of the semiconductor layer over the gate electrode to form source and drain electrodes; and

forming a pixel electrode.

2. The method according to claim 1 , wherein the metal layer is formed of Mo or an Mo alloy.

3. The method according to claim 2 , wherein the metal layer is etched by a dry etching.

4. The method according to claim 2 , wherein the pixel electrode is connected to a side portion of the drain electrode.

5. The method according to claim 1 , wherein the method of manufacturing a liquid crystal display device uses three photo masks.