Abstract: A method of selectively etching a titanium oxide layer with a view to the formation of a mask for the localization of the anodic oxidation of an underlying metallic layer.The method is characterized in that the material comprising the said titanium oxide layer is dipped in a solution of hydrogen peroxide and ammonia.Application to the formation of contacts on semiconductor devices.

Abstract: A method of etching aluminium oxide and/or cleaning aluminium surfaces with an etchant consisting of a solution of a fluoride in an organic solvent, which solution is substantially free from hydrofluoric acid and unbound water.

Abstract: A method of manufacturing a semiconductor device having a pattern of conductors, according to which method an auxiliary layer is formed which consists of two different sub-layers in which the negative of the desired pattern is provided and which is covered with a metal layer, in which the auxiliary layer and the said metal layer are then removed selectively.The method is characterized in that the auxiliary layer comprises a lowermost layer of an anodically oxidizable metal and an uppermost layer of the oxide of the said metal and may be used in the manufacture of semiconductor devices, especially transistors for very high frequencies and integrated circuits.

Abstract: The invention relates to a semiconductor device having a weakly doped region which comprises an ohmic contact.According to the invention the ohmic contact comprises two elements of which one causes in the semi-conductor body the same conductivity type as that of the region on which said contact is present.