Compositions and methods for forming and depositing metal films on semiconductor substrates using supercritical solvents

A composition for forming and depositing M(0) films on semiconductor substrates, the composition comprising at least one supercritical solvent to which has been added:

• at least one metal precursor, wherein the metal in the metal precursor has a first oxidation state which is a thermodynamically favored oxidation state of the metal;
• at least one reactive agent which reacts with the at least one metal precursor forming a reacted metal precursor, wherein the metal in the reacted metal precursor has a second oxidation state, and wherein the second oxidation state is lower than the first oxidation state and is less thermodynamically favored;
• neutral labile ligands;
• and
• at least one acid scavenger,
• wherein (i) the acid scavenger is selected from the group consisting of pyridine derivatives, silanes, carboxylate salts, lead salts, lead oxides, magnesium oxides, aluminum oxides, zinc oxides, hydrotalcites, and mixtures thereof, (ii) the acid scavenger is selected from the group consisting of alkyl substituted pyridines, and mixtures thereof, and/or (iii) the acid scavenger is selected from the group consisting of C1-C6 alkyl substituted pyridine derivatives, and mixtures thereof.

A method for depositing an elemental metal M(0) film on a semiconductor substrate comprising:

• heating the semiconductor substrate to obtain a heated semiconductor substrate;
• exposing the heated semiconductor substrate to a composition containing at least one metal precursor, an excess amount of neutral labile ligands, and a supercritical solvent;
• exposing the metal precursor to a reducing agent at or near the heated semiconductor substrate;
• reducing the metal precursor to the elemental metal M(0) by using the reducing agent;
• and
• depositing the elemental metal M(0) film while minimizing formation of metal oxides,
• wherein (i) the reducing agent is selected from the group consisting of zinc, magnesium, cadmium, mercury, sodium, potassium, lithium, aluminum, and alloys thereof, (ii) the reducing agent is selected from the group consisting of thiols, phosphines, and mixtures thereof, and/or (iii) the reducing agent is selected from the group consisting of sodium naphthalenide, lithium amines, Fe(II) complexes, cobaltocene, and mixtures thereof.

A method for depositing an elemental metal M(0) film on a semiconductor substrate comprising:

• exposing a first metal precursor to a reactive agent in the presence of a supercritical solvent containing an excess amount of neutral labile ligands, wherein the metal in the first metal precursor has a first oxidation state, wherein the first oxidation state is a thermodynamically favored oxidation state of the metal;
• forming in-situ a second metal precursor, wherein the metal in the second metal precursor has a second oxidation state, and wherein the second oxidation state is lower than the first oxidation state and is less thermodynamically favored;
• exposing the in-situ formed second metal precursor in the presence of the supercritical solvent and the neutral labile ligands to a reducing agent;
• reducing the in-situ formed second metal precursor to the elemental metal M(0);
• and
• depositing the elemental metal M(0) film on a semiconductor substrate while minimizing formation of metal oxides,
• wherein (i) the reducing agent is selected from the group consisting of zinc, magnesium, cadmium, mercury, sodium, potassium, lithium, aluminum, and alloys thereof, (ii) the reducing agent is selected from the group consisting of thiols, phosphines, and mixtures thereof, and/or (iii) the reducing agent is selected from the group consisting of sodium naphthalenide, lithium amines, Fe(II) complexes, cobaltocene, and mixtures thereof.