The present application provides a semiconductor structure manufacturing method and two semiconductor structures. The manufacturing method includes: providing a substrate and a silicon layer, the substrate exposing a top surface of the silicon layer; performing deposition to form an alloy layer on the silicon layer, the deposition being performed in a nitrogen-containing atmosphere, and a concentration of nitrogen atoms in the nitrogen-containing atmosphere increasing with an increase in deposition time; and annealing the alloy layer and the silicon layer. In embodiments of the present application, an increase in the concentration of nitrogen atoms can control a silicification reaction of the alloy layer, thereby preventing a line width effect and reducing the resistance of the semiconductor structure.