Some embodiments of the present disclosure provide a semiconductor structure. The semiconductor structure includes a substrate, a high k dielectric layer disposed over the substrate, and a gate layer over the high k dielectric layer. The high k dielectric layer is partially crystallized and comprising an average thickness of from about 10 Å to about 30 Å. Some embodiments of the present disclosure provide a method for manufacturing a semiconductor structure. The method includes (i) forming a high k dielectric layer with a thickness of from about 10 Å to about 30 Å over a substrate, (ii) forming a gate layer over the dielectric layer, and (iii) transforming at least a portion of the dielectric layer from a first phase to a second phase by microwave irradiation.