Semiconductor device and forming method thereof

A method of forming a semiconductor device includes forming a fin protruding from a substrate; forming a gate structure extending above the fin; forming a source/drain region in the fin adjacent to the gate structure; forming a first isolation region over the source/drain region; forming a first mask layer over the gate structure; etching the first isolation region using the first mask layer as an etching mask to form a first recess; conformally depositing a second mask layer over the first mask layer and within the first recess; depositing a third mask layer over the second mask layer; etching the third mask layer, the second mask layer and the first isolation region to form a second groove exposing the source/drain region; and depositing a conductive material in the second recess. The embodiment of the invention also provides a semiconductor device. 一种形成半导体器件的方法，包括形成从衬底突出的鳍；形成在鳍上方延伸的栅极结构；在与栅极结构相邻的鳍中形成源极/漏极区域；在源极/漏极区域上方形成第一隔离区域；在栅极结构上方形成第一掩模层；使用第一掩模层作为蚀刻掩模蚀刻第一隔离区域以形成第一凹槽；在第一掩模层上方和第一凹槽内共形地沉积第二掩模层；在第二掩模层上方沉积第三