Abstract <p>The results of the study of the influence of thermal annealing on the formation of ohmic contacts of aluminum-silicon and aluminum-polysilicon at the stage of manufacturing modern integrated circuits (ICs) are presented. It is established that standard thermal annealing at a temperature of 450°C for 20 min in nitrogen leads to both the dissolution of silicon in aluminum contacts with the subsequent formation of recrystallized islands of <i>p</i>-type silicon at the aluminum–silicon interface, and to the dissolution of polysilicon, with its subsequent precipitation in the form of sharp-angled conglomerates. When using rapid thermal annealing (<i>T</i>_max = 450°C, 7 s, N₂), the formation of such conglomerates is not detected. The dissolution of polysilicon (silicon) in aluminum during the formation of aluminum–polysilicon (aluminum–silicon) ohmic contacts leads to a change in the value of the contact resistance of polysilicon resistors and the current–voltage (I–V) characteristics of bipolar transistors.</p>