*Swizz Beatz is being sued by a songwriter who claims he co-produced the track “My Drink ‘n My 2 Step” but was not paid properly for his work.

In the lawsuit filed this week, Antwann Frost claims Swizz approached him in 2007 to help craft a hit single for rapper Cassidy’s then incomplete album.

According to the docs — obtained by TMZ — Swizz assembled the “drum patterns” and Frost created “all of the other original musical components that shaped and defined” the track that would become a chart-topping hit … spawning remixes by Kanye West, Ne-Yo, and Chingy.

The song was released soon after — at which point, Frost claims, Swizz low-balled him with a $5,000 cash offer and 5% ownership of the song while Swizz and Cassidy got the bulk share.

Frost rejected the offer, and is now suing for $1,500,000 claiming he deserves equal partnership in the song with Swizz and Cassidy.