Embodiments herein describe techniques for a semiconductor device having an interconnect structure including an inter-level dielectric (ILD) layer between a first layer and a second layer of the interconnect structure. The interconnect structure further includes a separation layer within the ILD layer. The ILD layer includes a first area with a first height to extend from a first surface of the ILD layer to a second surface of the ILD layer. The ILD layer further includes a second area with a second height to extend from the first surface of the ILD layer to a surface of the separation layer, where the first height is larger than the second height. Other embodiments may be described and/or claimed.