Patent FR-2816758-A1 (FR)
Title: Copper metallization for transistor connections and interconnections involves electrolytic deposition of diffusion barriers and layers of copper and copper alloys
Inventor: GIRARDIE LIONEL
IPC: H01L23/532
Filed: 2000-11-14
Abstract: Copper metallization involves electrolytic deposition of copper (Cu) diffusion barrier and copper (Cu) and Cu alloy layers, cleaning, depositing further copper layers and a protection layer, abrasion and planarization, depositing a Cu alloy layer, etching and depositing a further diffusion barrier. Copper metallization involves:  (a) etching a single or double damascene structure on a substrate surface, cleaning the walls of the structure, depositing a Cu diffusion barrier layer (2) of a metallic material (M) that is insoluble in Cu or an alloy of M and metals M1 and/or M2 that are at least partially soluble in M and Cu by an autocatalytic electrochemical process, and cleaning; (b) electrochemically depositing a Cu layer (3) of thickness less than 200 nm on (2), then annealing at 200-800 degrees C in H2, N2 or Ar for 1-240 minutes and cleaning; (c) electrochemically depositing a Cu and M3 alloy layer of thickness below 100 nm on layer (3) followed by annealing; (d) electrochemically depositing a Cu layer (5) of thickness less than 200 nm on layer (4), followed by annealing and cleaning; (e) electrochemically depositing a copper layer (6) of thickness 300 nm employing two different current phases, the first phase taking place in a low conductivity electrolytic bath at a current density of 0.5-5 mA/square cm between the cathode or substrate and a CuP anode for 5-20 seconds creating an equilibrium potential, and the second phase involving modification of the electrochemical equilibrium by applying a reverse periodic current for plating Cu according to Tafel kinetics at a current density of 20-50% of the Tafel current limit which modifies the potential, annealing at 15-105 degrees C for 30-180 seconds, and cleaning surface (6); (f) electrochemically depositing a Cu layer (7) on layer (6) by employing  first and second current phases that are the same as those in stage (e), followed by annealing at 250-600 degrees C in H2, N2 or Ar for 1-240 minutes; (g) electrochemically depositing a protection layer (8) of thickness below 5 nm on layers (6) and (7), followed by annealing at 15-100 degrees C for 30-180 seconds; (h) abrasion and planarization of the top of the electrochemically deposited layers (6) and (7) and protection layer (8) by chemical mechanical polishing at an increased selectivity with respect to layer (2) by using a chemical solution dispersed on an appropriate fabric and not containing a hydrosol phase; (i) electrochemically depositing a Cu and M3 alloy layer (9) of thickness below 200 nm on layers (6) and (7), followed by annealing; (j) partial electrolytic etching of layer (9) at an increased selectivity with respect to layer (2), to a thickness of 100 nm, to form a new layer (10), followed by annealing at 200-500 degrees C in H2 or N2 or Ar or O2 or in vacuum for 1-240 minutes; (k) dry or wet etching of layer (2) on the horizontal plane at an increased selectivity with respect to layer (10), followed by cleaning and preparing the surface of layer (10); and (l) electrochemically depositing a copper diffusion barrier layer (11) of thickness below 10 nm and comprising a metal M4 that is insoluble in Cu, or a binary or ternary alloy of M4 and metals M1 and/or M2, followed by annealing at 200-800 degrees C in H2 or N2 or Ar or O2 or in vacuum, for 1-240 minutes, followed by cleaning layer (11).