A faceplate for a substrate process chamber comprises a first and second surface. The second surface is shaped such that the second surface includes a peak and a distance between the first and second surface varies across the width of the faceplate. The second surface of the faceplate is exposed to a processing volume of the process chamber. Further, the faceplate may be part of a lid assembly for the process chamber. The lid assembly may include a blocker plate facing the first surface of the faceplate. A distance between the blocker plate and the first surface is constant.