Thin film transistor array panel and manufacturing method thereof

A thin film transistor array panel includes a substrate and a thin film transistor disposed on a surface of the substrate. The thin film transistor includes a semiconductor, a source electrode, and a drain electrode that are disposed on a same layer as one another. The semiconductor is between the source electrode and the drain electrode. The thin film transistor array panel further includes a buffer layer disposed between the semiconductor and the substrate and including an inorganic insulating material. The first edge of the buffer layer is substantially parallel to an adjacent edge of the semiconductor, a second edge of the buffer layer is substantially parallel to an adjacent edge of the source electrode, and a third edge of the buffer layer is substantially parallel to an adjacent edge of the drain electrode.