Method for manufacturing polysilicon layer and thin film transistor including the polysilicon layer

A thin film transistor of a display device, comprising:

• a second polysilicon layer formed by a manufacturing method of a polysilicon layer, the method comprising:
• irradiating a first excimer laser beam having a first energy density to an amorphous silicon layer including an oxidation layer thereon, to form a first polysilicon layer including thereon portions of the oxidation layer at grain boundaries of the first polysilicon layer;
• removing the portions of the oxidation layer at the grain boundaries of the first polysilicon layer;
• and
• irradiating a second excimer laser beam having a second energy density of 80% to 100% of the first energy density to the first polysilicon layer from which the portions of the oxidation layer at the grain boundaries thereof are removed, to form the second polysilicon layer of the thin film transistor;
• and
• a gate electrode on the second polysilicon layer formed by the manufacturing method of the polysilicon layer,
• wherein a root mean square of surface roughness of the second polysilicon layer formed by the manufacturing method of the polysilicon layer is about 2 nanometers to about 7 nanometers.

A thin film transistor of a display device, comprising:

• a second polysilicon layer formed by a manufacturing method of a polysilicon layer, the method comprising:
• irradiating a first excimer laser beam having a first energy density to an amorphous silicon layer including an oxidation layer thereon, to form a first polysilicon layer including thereon portions of the oxidation layer at grain boundaries of the first polysilicon layer;
• removing the portions of the oxidation layer at the grain boundaries of the first polysilicon layer;
• and
• irradiating a second excimer laser beam having a second energy density of 80% to 100% of the first energy density to the first polysilicon layer from which the portions of the oxidation layer at the grain boundaries thereof are removed, to form the second polysilicon layer of the thin film transistor;
• and
• a gate electrode on the second polysilicon layer formed by the manufacturing method of the polysilicon layer,
• wherein a peak-to-valley value of a maximum surface roughness of the second polysilicon layer formed by the manufacturing method of the polysilicon layer is about 10 nanometers to about 30 nanometers.