Patent ID: 7696088

Claim:
A method of forming a gate line and gate electrode, comprising the steps of: 1) providing a substrate; 2) forming a photoresist layer on the substrate, a photoresist pattern being formed complementary with a pattern of the gate line and gate electrode, wherein the photoresist layer has a thickness in a range of about 1 to about 3 μm; 3) forming a metal Cu thin film or a composite thin film comprising a metal Cu thin film on the resulting substrate; and 4) removing the photoresist pattern and the metal Cu thin film or the composite thin film comprising the metal Cu thin film formed thereon from the resulting substrate, including immersing the resulting substrate into a lifting-off solution that comprises a mixture selected from the group consisting of a mixture of isopropanol and copper sulfate, a mixture of isopropanol, copper sulfite and sulfuric acid, and a mixture of isopropanol and sulfurous acid, wherein the content of the copper sulfate, the copper sulfite and sulfuric acid, and the sulfurous acid is less than about 5% by weight, so as to form the gate line and gate electrode comprising the metal Cu thin film or the composite thin film comprising the metal Cu thin film.