Method of via formation for the multilevel interconnect integrated circuits

A method for forming an integrated circuit contact structure, comprising the steps of:

• forming a metal conductive element over a lower insulating layer;
• forming a conformal oxide layer over said metal conductive element and said lower insulating layer;
• forming a layer of spin on glass over said conformal oxide layer;
• forming a barrier layer over said conformal oxide layer;
• forming an insulating layer over said barrier layer, wherein the barrier layer is made of a material that is not etched by a wet etch that etches said insulating layer;
• depositing and patterning a photoresist layer over said insulating layer;
• performing a wet etch part way through the insulating layer in a region defined by the patterned photoresist layer, leaving a remainder of the insulating layer which is not etched through;
• and
• performing an anisotropic etch through the remainder of the insulating layer, the barrier layer, and the conformal oxide layer in the region defined by the patterned photoresist layer to expose a portion of the metal conductive element;
• wherein the insulating layer has a crack in the region defined by the patterned photoresist layer, wherein the crack extends through the insulating layer to the barrier layer, and wherein, during the step of performing a wet etch, the barrier layer acts as an etch stop for etchant which moves through the crack.