Systems and methods for deposition of molybdenum for source/drain contacts
Disclosed herein are systems and methods method for thin film deposition of molybdenum for source/drain formation. A deposition process may be performed in which the surface is contacted in the reaction chamber with a first oxygen-free molybdenum halide reactant at a first temperature, wherein said contacting with the first oxygen-free molybdenum halide reactant forms at least one layer of molybdenum on the substrate. In some embodiments, the temperature of the reaction chamber may be raised from the first temperature to a second temperature. In some embodiments, the substrate in the reaction chamber may be contacted with a second oxygen-free molybdenum halide reactant at the second temperature, wherein said contacting with the second oxygen-free molybdenum halide reactant forms at least one layer of molybdenum on the substrate. In some embodiments, the deposition at the second temperature may be repeated until a molybdenum-containing film of desired thickness is formed.
1 . A method for thin film deposition, the method comprising:
providing a substrate in a reactor;
performing a surface clean on a surface of the substrate, wherein the surface clean comprises removing a surface oxide from the surface of the substrate by contacting the surface with an etchant;
after the step of removing the surface oxide, exposing the substrate to a plasma comprising H 2 and Ar;
performing a deposition process comprising:
a) contacting the surface of the substrate in the reactor with a first oxygen-free molybdenum halide reactant at a first temperature, wherein contacting with the first oxygen-free molybdenum halide reactant forms at least one layer of molybdenum on the substrate;
b) raising the temperature of the reactor from the first temperature to a second temperature;
c) contacting the substrate in the reactor with a second oxygen-free molybdenum halide reactant at the second temperature, wherein contacting with the second oxygen-free molybdenum halide reactant forms at least one layer of molybdenum on the substrate; and
optionally, repeating step c) until a molybdenum-containing film of desired thickness is formed,
wherein the temperature of the reactor is raised while the substrate is contacted with the first oxygen-free molybdenum halide reactant and/or the second oxygen-free molybdenum halide reactant.
2 . The method of claim 1 , wherein the first oxygen-free molybdenum halide reactant and the second oxygen-free molybdenum halide reactant comprise MoCl 5 .
3 . The method of claim 2 , wherein MoCl 5 is continuously flowed into the reactor during the deposition process.
4 . The method of claim 1 , wherein the deposition process further comprises ceasing contacting the surface of the substrate in the reactor with the first oxygen-free molybdenum halide reactant prior to raising the temperature of the reactor from the first temperature to the second temperature.
5 . The method of claim 1 , wherein the surface clean further comprise removing an etchant residue from the surface.
6 . The method of claim 1 , wherein the surface of the substrate is contacted with the first oxygen-free molybdenum halide reactant in a first reaction chamber of the reactor and contacted with the second oxygen-free molybdenum halide reactant in a second reaction chamber of the reactor, wherein the first reaction chamber is in gas isolation from the second reaction chamber.
7 . The method of claim 1 , wherein the molybdenum-containing film of desired thickness comprises a resistivity of less than about 50 μΩcm.
8 . The method of claim 1 , wherein the molybdenum-containing film of desired thickness comprises a three-dimensional structure having at least 90% conformality.
9 . The method of claim 1 , wherein the molybdenum-containing film of desired thickness forms a structure having an aspect ratio of more than about 3:1 and wherein the film has step coverage of more than about 80%.
10 . The method of claim 1 , wherein the first temperature is less than 400° C.
11 . The method of claim 10 , wherein the second temperature is greater than 450° C.
12 . The method of claim 1 , wherein the deposition process comprises atomic layer deposition (ALD) on the substrate.
13 . The method of claim 1 , wherein the molybdenum-containing film of desired thickness comprises a source or drain contact structure of a field effect transistor.
14 . The method of claim 1 , wherein the surface comprises silicon, germanium, or silicon germanium.
15 . The method of claim 1 , wherein the repeating step c) is by using temporally spaced reactant pulses.
16 . The method of claim 1 , wherein the removing the surface oxide from the surface of the substrate is by contacting the surface with one or more of Ar, TT, NH 3 , and NF 3 .
17 . The method of claim 1 , wherein the ratio of H 2 to Ar is between 1:10 and 1:5.
18 . The method of claim 5 , wherein the removing an etchant residue comprises evaporation.
19 . A substrate processing system, comprising:
a reaction chamber for accommodating one or more substrates;
a control unit comprising one or more processors and non-transitory computer-readable media storing instructions for controlling the substrate processing system, wherein the instructions, when executed by the one or more processors, cause the substrate processing system to:
provide a substrate in the reactor;
perform a surface clean of a surface of the substrate, wherein the surface clean comprises removing a surface oxide from the surface of the substrate by contacting the surface with an etchant;
after the step of removing the surface oxide, expose the substrate to a plasma comprising H 2 and Ar;
perform a deposition process comprising:
a) contact the surface of the substrate in the reactor with a first oxygen-free molybdenum halide reactant at a first temperature, wherein said contacting with the first oxygen-free molybdenum halide reactant forms at least one layer of molybdenum on the substrate;
b) raise the temperature of the reactor from the first temperature to a second temperature;
c) contact the substrate in the reactor with a second oxygen-free molybdenum halide reactant at the second temperature, wherein said contacting with the second oxygen-free molybdenum halide reactant forms at least one layer of molybdenum on the substrate, wherein the second temperature is higher than the first temperature; and
repeat step c) until a molybdenum-containing film of desired thickness is formed,
wherein the temperature of the reactor is raised while the substrate is contacted with the first oxygen-free molybdenum halide reactant and/or the second oxygen-free molybdenum halide reactant.