Substantially carbon-free molybdenum-containing and tungsten-containing films in semiconductor device manufacturing
Substantially carbon-free molybdenum-containing and tungsten-containing films are deposited on semiconductor substrates using halide-free metalorganic precursors. The precursors do not include metal-carbon bonds, carbonyl ligands, and, preferably do not include beta-hydrogen atoms. Metal-containing films, such as molybdenum nitride, molybdenum oxynitride, molybdenum silicide, and molybdenum boride with carbon content of less than about 5% atomic, such as less than about 3% atomic are deposited. The films are deposited in some embodiments by reacting the metal-containing precursor with a reactant on a surface of a substrate in an absence of plasma, e.g. using several ALD cycles. In some embodiments the formed film is then treated with a second reactant in a plasma to modify its properties (e.g., to densify the film, to reduce resistivity of the film, or to increase its work function). The films can be used as liners, diffusion barriers, and as electrode material in pMOS devices.
1 . A method of forming a substantially carbon-free metal-containing layer on a semiconductor substrate, the method comprising:
(a) introducing a metal-containing precursor into a processing chamber housing the semiconductor substrate, wherein the metal-containing precursor is a halide-free, carbonyl-free compound that comprises at least one ligand, bound to a metal selected from the group consisting of molybdenum and tungsten, wherein the halide-free, carbonyl-free compound does not include metal-carbon bonds and metal-oxygen double bonds; and
(b) reacting the metal-containing precursor with at least one reactant in an absence of plasma to form a metal-containing layer on the semiconductor substrate, wherein the formed metal-containing layer is a substantially carbon-free molybdenum-containing or tungsten-containing layer that has a carbon content of less than about 5 atomic %, wherein the layer is selected from the group consisting of Mo, W, MON, WN, MOON, WON, MOB, WB, MoSi, WSi layer and combinations thereof.
2 . The method of claim 1 , wherein the formed metal-containing layer has a carbon content of less than about 2 atomic %.
3 . The method of claim 1 , wherein the metal-containing precursor does not include beta-hydrogen atoms.
4 . The method of claim 1 , wherein the formed metal-containing layer is selected from the group consisting of Mo, MON, and MOON.
5 . The method of claim 1 , wherein the metal-containing precursor is selected from the group consisting of precursors 1-16, wherein each R and RI is independently selected from the group consisting of an alkyl, fluoroalkyl, and alkylsilyl, wherein R does not include beta hydrogen bonds, n is 1-4 and m is 1-4.
6 . The method of claim 1 , wherein the metal-containing precursor is a compound selected from compounds 17-20.
7 . The method of claim 1 , further comprising:
(c) treating the formed metal-containing layer with a nitrogen-containing reactant and increasing nitrogen content in the metal-containing layer.
8 . The method of claim 7 , wherein the treated metal-containing layer is a MON layer having a work function of greater than about 4.9 eV.
9 . The method of claim 1 , further comprising:
(c) densifying the formed metal-containing layer by treating the metal-containing layer with a plasma formed in a process gas comprising H 2 .
10 . The method of claim 1 , wherein in (b) the reaction between the metal-containing precursor and the at least one reactant occurs on the surface of the semiconductor substrate.
11 . The method of claim 1 , wherein the substantially carbon-free metal-containing layer is a diffusion barrier layer or a liner layer.
12 . The method of claim 1 , wherein the method comprises forming the substantially carbon-free metal-containing layer having a work function of greater than about 5.0 eV in a pMOS device.
13 . The method of claim 1 , wherein forming the substantially carbon-free metal layer having a work function of greater than about 5.0 eV, comprises treating the semiconductor substrate after (b) with a plasma-activated nitrogen-containing reactant, to increase nitrogen content in the metal-containing layer.
14 . The method of claim 1 , wherein the substantially carbon-free metal layer is formed in (b) at a temperature of less than about 450° C.