A manufacturing method of a DRAM memory cell, comprising: providing a substrate; forming an ion implantation area in the substrate, an upper surface of the ion implantation area having a distance from an upper surface of the substrate; forming an initial word line trench in the substrate, the initial word line trench extending from the upper surface of the substrate into the ion implantation area; and widening the initial word line trench to form a word line trench, a width of a bottom of the word line trench being greater than a minimum width of the word line trench; characterized in that: wherein, the ion implantation area is a first doped area; and before the ion implantation area is formed in the substrate, the manufacturing method of a DRAM memory cell further comprises: forming a second doped area in the substrate, the second doped area being located above the first doped area and extending to the upper surface of the substrate, the initial word line trench penetrating the second doped area and extending into the first doped area, the first doped area being a doped area of a first conductive type, and the second doped area being a doped area of a second conductive type; wherein, widening the initial word line trench to form the word line trench comprises: wet etching the initial word line trench with a wet etching solution to obtain the word line trench, an etching rate of the wet etching solution to a part of the initial word line trench in the first doped area being greater than an etching rate of the wet etching solution to a part of the initial word line trench in the second doped area. providing a substrate; forming an ion implantation area in the substrate, an upper surface of the ion implantation area having a distance from an upper surface of the substrate; forming an initial word line trench in the substrate, the initial word line trench extending from the upper surface of the substrate into the ion implantation area; and widening the initial word line trench to form a word line trench, a width of a bottom of the word line trench being greater than a minimum width of the word line trench; characterized in that: wherein, the ion implantation area is a first doped area; and before the ion implantation area is formed in the substrate, the manufacturing method of a DRAM memory cell further comprises: forming a second doped area in the substrate, the second doped area being located above the first doped area and extending to the upper surface of the substrate, the initial word line trench penetrating the second doped area and extending into the first doped area, the first doped area being a doped area of a first conductive type, and the second doped area being a doped area of a second conductive type; wherein, widening the initial word line trench to form the word line trench comprises: wet etching the initial word line trench with a wet etching solution to obtain the word line trench, an etching rate of the wet etching solution to a part of the initial word line trench in the first doped area being greater than an etching rate of the wet etching solution to a part of the initial word line trench in the second doped area. wherein, the ion implantation area is a first doped area; and before the ion implantation area is formed in the substrate, the manufacturing method of a DRAM memory cell further comprises: forming a second doped area in the substrate, the second doped area being located above the first doped area and extending to the upper surface of the substrate, the initial word line trench penetrating the second doped area and extending into the first doped area, the first doped area being a doped area of a first conductive type, and the second doped area being a doped area of a second conductive type; wherein, widening the initial word line trench to form the word line trench comprises: wet etching the initial word line trench with a wet etching solution to obtain the word line trench, an etching rate of the wet etching solution to a part of the initial word line trench in the first doped area being greater than an etching rate of the wet etching solution to a part of the initial word line trench in the second doped area.