US 6,444,580 B1 · Method of reducing carbon, sulphur, and oxygen impurities in a calcium-doped copper surface and semiconductor device thereby formed

Abstract

A method of fabricating a semiconductor device having contaminant-reduced calcium-copper (Ca—Cu) alloy surfaces formed on Cu interconnects by cost-effectively removing the contaminant layer and a device thereby formed. Contaminant removal from a Cu—Ca—X surface, where contaminant X=C, S, or O, is achieved by sputtering the Cu—Ca—X surface in an argon (Ar) atmosphere between the steps of (a) immersing the Cu interconnect surface into an electroless plating solution comprising Cu salts, Ca salts, their complexing agents, a reducing agent, a pH adjuster, and at least one surfactant for facilitating Ca-doping of the Cu interconnect material; and (b) annealing of the Ca—Cu alloy surface onto the underlying Cu interconnect material to form a Ca—Cu/Cu interconnect structure, whereby the sputtering step, under Ar, selectively and effectively removes contaminants from the Cu—Ca—X layer containing higher concentrations of C, S, or O, thereby minimizing the post-annealed contaminant level, and thereby producing a uniform Ca—Cu alloy surface (i.e., Cu-rich with 0.2-5% Ca) on the Cu interconnect material for maximizing Ca—Cu/Cu interconnect structure reliability, electromigration resistance, and corrosion prevention. The annealing step primarily removes O and secondarily removes C and S, especially when performed under vacuum, an inert gas, or a reducing ambient such as ammonia (NH3) plasma. Thus, the resultant device then comprises a distinctive contaminant-reduced Ca—Cu/Cu interconnect structure.

Claims10

Dependent claims

A method of fabricating a semiconductor device having a contaminant-reduced copper-calcium alloy surface on a copper (Cu—Ca/Cu) interconnect structure, comprising:

a. providing a semiconductor substrate;
b. depositing a copper (Cu) film on the semiconductor substrate;
c. treating the Cu film in an electroless plating solution for facilitating doping of the Cu film with at least one plurality of ions selected from a group of ions consisting essentially of Cu ions and calcium (Ca) ions, thereby forming a Cu—Ca—X film on the Cu film, wherein X denotes at least one contaminant;
d. processing the Cu—Ca—X film by a technique selected from a group of techniques consisting essentially of:
(1) sputtering under an argon (Ar) atmosphere, and
(2) treating in a plasma ambient, thereby removing the at least one contaminant, and thereby effecting a thin Cu—Ca film on the Cu film;
e. annealing the thin Cu—Ca film, whereby the thin Cu—Ca film is alloyed, thereby forming a contaminant-reduced Cu—Ca alloy surface on the Cu film, and thereby forming the contaminant-reduced Cu—Ca/Cu interconnect structure comprising the contaminant-reduced Cu—Ca alloy surface on the semiconductor substrate;
and
f. completing formation of the semiconductor device.

6 more elements

A method of fabricating a semiconductor device having a contaminant-reduced copper-calcium alloy surface on a copper (Cu—Ca/Cu) interconnect structure, comprising:

a. providing a semiconductor substrate;
b. depositing a Cu film on the semiconductor substrate by a technique selected from a group of techniques consisting essentially of electroplating, electroless plating, chemical vapor deposition (CVD), plasma vapor deposition (PVD), and plasma enhanced chemical vapor deposition (PECVD);
c. treating the Cu film in an electroless plating solution for facilitating doping of the Cu film with at least one plurality of ions selected from a group of ions consisting essentially of Cu ions and Ca ions, the solution comprising:
(1) at least one solvent;
(2) at least one Cu salt;
(3) at least one Ca salt;
(4) at least one completing agent;
(5) at least one reducing agent;
(6) at least one pH adjuster;
and
(7) at least one surfactant,
(2) through (7) being dissolved in (1),
thereby depositing a Cu—Ca—X film on the Cu film, wherein X denotes at least one contaminant selected from a group of contaminants consisting essentially of C, S, and O;
d. processing the Cu—Ca—X film by a technique selected from a group of techniques consisting essentially of:
(1) sputtering under an Ar atmosphere, and
(2) treating in a plasma ambient, thereby removing at least one contaminant from the Cu—Ca—X film, and thereby effecting a thin Cu—Ca film on the Cu film;
e. annealing the thin Cu—Ca film in a temperature range of 250° C. to 450° C. in an environment selected from a group of environments consisting essentially of a vacuum, an inert gas, and a reducing ambient,
whereby the thin Cu—Ca film is alloyed,
thereby forming a contaminant-reduced Cu—Ca alloy surface on the Cu film,
wherein the thin contaminant-reduced Cu—Ca alloy surface is Cu-rich with a Ca-doping level in a range of 0.2 atomic % to 5 atomic %, and
thereby forming a contaminant-reduced Cu—Ca/Cu interconnect structure comprising the thin contaminant-reduced Cu—Ca alloy surface on the semiconductor substrate;
and
f. completing formation of the semiconductor device.

20 more elements

Dependencies are inferred from the claim text.

Method of reducing carbon, sulphur, and oxygen impurities in a calcium-doped copper surface and semiconductor device thereby formed

Life of this patent

Method of reducing carbon, sulphur, and oxygen impurities in a calcium-doped copper surface and semiconductor device thereby formed

Life of this patent

Abstract

Claims10