Abstract: Methods for forming semiconductor structures are provided. The method for manufacturing a semiconductor structure includes forming a hard mask structure over a substrate and etching the substrate through an opening of the hard mask structure to form a trench. The method for manufacturing a semiconductor structure further includes removing a portion of the hard mask structure to enlarge the opening and forming an epitaxial-growth structure in the trench and the opening.

Abstract: Methods for forming semiconductor structures are provided. The method for manufacturing a semiconductor structure includes forming a hard mask structure over a substrate and etching the substrate through an opening of the hard mask structure to form a trench. The method for manufacturing a semiconductor structure further includes removing a portion of the hard mask structure to enlarge the opening and forming an epitaxial-growth structure in the trench and the opening.

Abstract: An electrostatic discharge protection circuit is used in an integrated circuit with a first sub-circuit working with a first working voltage source and a second sub-circuit working with a second working voltage source lower than the first working voltage source. The electrostatic discharge protection circuit includes a first metal-oxide-semiconductor transistor of a first conductive type, having a drain thereof electrically connected to a pad of the integrated circuit, and gate, source and bulk thereof electrically connected to a bulk voltage; and a guard ring of the first conductive type, surrounding the first metal-oxide-semiconductor transistor of the first conductive type and coupled to the second working voltage source.