An antifuse one-time programmable (OTP) memory cell includes a semiconductor substrate, an isolation region, and a fin structure protruding from a top surface of the isolation region. The fin structure has an end portion with a sidewall surface above the top surface. A select gate transistor is disposed on the fin structure. The select gate transistor has a select gate traversing the fin structure, a select gate dielectric layer, a drain region, and a source region. A vertical program gate transistor is serially connected to the select gate transistor through the source region. The vertical program gate transistor has a program gate directly disposed on the isolation region and covering the sidewall surface of the end portion, and a program gate dielectric layer between the program gate and the sidewall surface.