Spatial selectivity of layer disordering induced in GaAs/AlGaAs quantum well heterostructures using SiO2and Si3N4capping and annealing was investigated using low temperature photoluminescence in conjunction with cross-sectional transmission electron microscopy. Comparative study reveals opposite behaviors for patterned Si3N4covered with SiO2and patterned SiO2covered with Si3N4. In the former, layer disordering occurs in the regions located under the SiO2strips and in the latter, layer disordering surprisingly occurs under the Si3N4strips while it is inhibited in the SiO2-capped areas. These results are in agreement with a proposed interdiffusion model based on the effect on Ga vacancy diffusion of the stress distribution generated in the heterostructure during annealing by the capping layers. This work clearly demonstrates that the diffusion of point defects, such as the Ga vacancies, which are responsible for the layer disordering, can be piloted by the stress field imposed to the semiconductor and opens new perspectives for defect engineering.