Forming of the last metallization level of an integrated circuit
An integrated circuit including one or several metallization levels, metal conductive strips and metal contact pads being formed on the last metallization level, the last level being covered with a passivation layer in which are formed openings above the contact pads. The thickness of the pads, at least at the level of their portions not covered by the passivation layer, is smaller than the thickness of said conductive strips.
1. An integrated circuit comprising one or several metallization levels, metal conductive strips and a metal contact pad being formed on a last metallization level, wherein the metal contact pad has a first length, a first width, and a first thickness, the first thickness being the distance from a bottom of the metal contact pad to a top of the metal contact pad, wherein the first length and the first width are greater than the first thickness, the last level being covered with a passivation layer in which is formed an opening above the contact pad, wherein the metal conductive strips have a second thickness along a same direction as the first thickness, wherein the first thickness of the metal contact pad, over an entire area of the metal contact pad not covered by the passivation layer, is smaller than the second thickness of said conductive strips prior to application of an external contact to the metal contact pad, wherein the entire top of the metal contact pad within the opening has a substantially flat surface extending substantially throughout the entire opening.
2. The integrated circuit of claim 1 , wherein at least one conductive strip forms a coil.
3. The integrated circuit of claim 1 , wherein several of said conductive strips form a supply network.
4. The integrated circuit of claim 1 , wherein the last metallization level is formed on an insulating layer, each contact pad being formed of a conductive layer covering an insulating portion laid on the insulating layer.
5. The integrated circuit of claim 1 , wherein the contact pad is made of aluminum.
6. The integrated circuit of claim 1 , wherein the second thickness is at least about twice as large as the first thickness.
7. A method for forming the last metallization level of the integrated circuit of claim 1 , comprising:
depositing a metal layer on a substrate;
etching the metal layer to form a metal portion and said conductive strips;
covering the substrate, the conductive strips, and the metal portion with a passivation layer;
forming an opening in the passivation layer above the metal portion; and
partially etching the metal portion to decrease the thickness of the metal portion to obtain said contact pad; wherein a first thickness over an entire area of the metal contact pad not covered by the passivation layer, is smaller than a second thickness of said conductive strips.
8. A method for forming the last metallization level of the integrated circuit of claim 1 , comprising:
depositing a metal layer on a substrate;
etching the metal layer to form a metal portion and said conductive strips;
covering the conductive strips with a protection layer;
partially etching the metal portion to decrease the thickness of the metal portion to obtain said contact pad;
removing, if necessary, the protection layer;
covering the substrate, the conductive strips, and the contact pad with a passivation layer; and
forming an opening in the passivation layer above the contact pad; wherein the thickness over an entire area of the metal portion not covered by the passivation layer, is smaller than a second thickness of said conductive strips.