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Methods and apparatus are used for electrochemical planarization of an electrically conductive material surface with varying topography from a partially fabricated integrated circuit, in which protruding regions of the conductive material are removed more quickly than recessed regions to thereby inc

Methods and apparatus are used for electrochemical planarization of an electrically conductive material surface with varying topography from a partially fabricated integrated circuit, in which protruding regions of the conductive material are removed more quickly than recessed regions to thereby increase the planarity of the conductive material surface. This is accomplished by using dissolution electrochemistry. The partially fabricated integrated circuit is used as the anode in an electrochemical cell, with the anode and cathode active surfaces positioned in very close proximity. By using highly resistive electrolyte and moving the anode and cathode progressively closer during electrochemical dissolution, the electrically conductive material surface is effectively planarized.

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Methods and apparatus are used for electrochemical planarization of an electrically conductive material surface with varying topography from a partially fabricated integrated circuit, in which protruding regions of the conductive material are removed more quickly than recessed regions to thereby inc

Methods and apparatus are used for electrochemical planarization of an electrically conductive material surface with varying topography from a partially fabricated integrated circuit, in which protruding regions of the conductive material are removed more quickly than recessed regions to thereby increase the planarity of the conductive material surface. This is accomplished by using dissolution electrochemistry. The partially fabricated integrated circuit is used as the anode in an electrochemical cell, with the anode and cathode active surfaces positioned in very close proximity. By using highly resistive electrolyte and moving the anode and cathode progressively closer during electrochemical dissolution, the electrically conductive material surface is effectively planarized. e method of claim 3 wherein the trench opening in said third layer has been pulled back by a process comprising the removal of an annular region of said third layer surrounding said opening, exposing, thereby, an annular region of the surface of said second layer and creating a cross-sectional stepped profile of said trench, wherein the diameter of the opening in said third layer now exceeds the initial outside diameter of the trench opening to create, thereby, the trench step. 5. The method of claim 4 wherein the first substrate layer is a layer of semiconductor material, the second substrate layer is an oxide layer and the third layer is a nitride layer. 6. The method of claim 5 wherein the semiconductor material is silicon. 7. The method of claim 6 wherein the oxide layer is silicon oxide formed to a thickness of between approximately 50 and 250 angstroms. 8. The method of claim 7 wherein the nitride layer is a layer of silicon nitride formed to a thickness of between approximately 1000 and 2000 angstroms. 9. The method of claim 8 wherein the initial diameter of the trench opening before the pulling back of said silicon nitride layer is not more than approximately 0.2 microns. 10. The method of claim 5 wherein the deposition and sputtering to form said initial layer are carried out with low bias power which is less than approximately 1000 W to avoid damage to the nitride layer. 11. The method of claim 5 wherein the first process time is sufficient to allow the formation of an initial layer that has no overhang on the trench sidewall beneath the trench step and has a sufficient thickness to protect said nitride layer during the subsequent processing. 12. The method of claim 5 wherein the second process time is sufficient to maintain a minimal overhang on the trench sidewall beneath the trench step, to eliminate damage to the nitride layer and to allow the formation of a wide opening in the partially filled trench. 13. The method of claim 1 wherein the height of the fill above the upper surface of the substrate is between approximately 0.1 and 0.3 times the initial depth of the trench.