Interconnect structures comprising capping layers with low dielectric constants and methods of making the same

A method for forming an integrated circuit structure, comprising:

• forming a conductive interconnect embedded in an interlevel dielectric layer disposed above a semiconductor substrate;
• depositing a first capping layer comprising SiwCxNyHz upon the conductive interconnect;
• depositing a second capping layer comprising SiaCbNcHd having a dielectric constant less than about 4 upon the first capping layer;
• depositing a third capping layer comprising SiwCxNyHz upon the second capping layer,
• wherein the second capping layer has a lower nitrogen content than the first capping layer, and wherein the second capping layer has a lower nitrogen content than the third capping layer,
• wherein the second capping layer has a treated layer extending therethrough, between top and bottom surfaces of the second capping layer, wherein the treated layer incorporates includes additional nitrogen atoms incorporated therein with respect to untreated portions of the capping layer,
• wherein a+b+c+d=1.0 and a, b, c, and d are each greater than 0 and less than 1, and
• wherein w+x+y+z=1.0 and w, x, y, and z are each greater than 0 and less than 1.