A method of forming a semiconductor device includes depositing a flowable dielectric layer on a substrate and annealing the flowable dielectric layer. The method further includes performing a high temperature (HT) doping process on the flowable dielectric layer. The HT doping process may include implanting dopant ions into the flowable dielectric layer and heating the substrate during the implanting of the dopant ions. The heating of the substrate may include heating a substrate holder upon which the substrate is disposed and maintaining the substrate at a temperature above 100° C. An example benefit reduced the wet etch rate (WER) of the flowable dielectric layer.