A fabrication method to form a lateral superjunction structure in a semiconductor device uses N and P type ion implantations into a base epitaxial layer. In some embodiments, the base epitaxial layer is an intrinsic epitaxial layer or a lightly doped epitaxial layer. The method performs simultaneous N and P type ion implantations into the base epitaxial layer. The epitaxial and implantation processes are repeated successively to form multiple implanted base epitaxial layers on a semiconductor base layer. After the desired number of implanted base epitaxial layers is formed, the semiconductor structure is subjected to annealing to form a lateral superjunction structure including alternate N and P type thin semiconductor regions. In particular, the alternating N and P type thin superjunction layers are formed by the ion implantation process and subsequent annealing. The fabrication method of the present invention ensures good charge control in the lateral superjunction structure.