The morphology of copper precipitate colonies in silicon is determined completely by a dislocation climb and glide mechanism. Interstitial dislocation loops, originating from three‐dimensional nucleation centers are involved. Preferential climb in ⟨110⟩ directions of the ⟨100⟩ oriented edges of interstitial loops parallel to {110} planes and with b=⟨110⟩ determines the orientation of the colonies. The memory effect is ascribed to lattice defects which remain after complete out‐diffusion of the copper.