Embodiments herein describe techniques for an integrated circuit (IC). The IC may include a lower device layer that includes a first transistor structure, an upper device layer above the lower device layer including a second transistor structure, and an isolation wall that extends between the upper device layer and the lower device layer. The isolation wall may be in contact with an edge of a first gate structure of the first transistor structure and an edge of a second gate structure of the second transistor structure, and may have a first width to the edge of the first gate structure at the lower device layer, and a second width to the edge of the second gate structure at the upper device layer. The first width may be different from the second width. Other embodiments may be described and/or claimed.