In males, sperms are produced by spermatogonia (immature germ cells). They are located in the inner walls of the seminiferous tubules.
Spermatogonia divide by mitosis and are diploid. Some of the spermatogonia (primary spermatocytes) undergo meiosis periodically. After the first meiotic division, two haploid secondary spermatocytes are formed. They further divide by meiosis to give rise to four haploid spermatids. These spermatids are then transformed into sperms by the process of spermiogenesis.
Hence, the spermatids formed are haploid.