In one aspect, a method of forming a semiconductor device can comprise forming a first transistor structure and a second transistor structure separated by a first trench which comprises a first dielectric wall protruding above a top surface of the transistor structures. The first and the second transistor structures each can comprise a plurality of stacked nanosheets forming a channel structure, and a source portion and a drain portion horizontally separated by the channel structure. The method further can comprise depositing a contact material over the transistor structures and the first dielectric wall, thereby filling the first trench and contacting a first source/drain portion of the first transistor structure and a first source/drain portion of the second transistor structure. Further, the method can comprise etching back the contact material layer below a top surface of the first dielectric wall, thereby forming a first contact contacting the first source/drain portion of the first transistor structure, and a second contact contacting the first source/drain portion of the second transistor structure.