A system for processing a substrate includes a chamber having a chamber wall that defines a lower chamber portion and an upper chamber wall that defines an upper chamber portion. A showerhead is disposed in the upper chamber portion. A pedestal with a support for the substrate is disposed in the lower chamber portion and oriented below the showerhead, such that a processing region is defined between the support of the pedestal and the showerhead. A spacer is disposed between the showerhead and the lower chamber wall of the lower chamber portion. The spacer is defined by an annular body that includes a vertical component. The annular body also includes a side extension that is disposed outside of the processing region and projects radially away from the vertical component. The annular body includes a groove that is formed in the side extension so as to surround the vertical component of the annular body. A heating element is embedded in the groove of the side extension.