PLASMA MEDIATED ASHING PROCESSES
A plasma ashing process for removing photoresist, polymers and/or residues from a substrate comprises placing the substrate including the photoresist, polymers, and/or residues into a reaction chamber; generating a plasma from a gas mixture comprising oxygen gas (O 2 ) and/or an oxygen containing gas; suppressing and/or reducing fast diffusing species in the plasma; and exposing the substrate to the plasma to selectively remove the photoresist, polymers, and/or residues from the substrate, wherein the plasma is substantially free from fast diffusing species.
1 . A plasma ashing process for removing photoresist, polymers and/or residues from a substrate, the process comprising:
placing the substrate including the photoresist, polymers, and/or residues into a reaction chamber;
generating a plasma from a gas mixture comprising oxygen gas (O 2 ) and/or an oxygen containing gas;
suppressing and/or reducing fast diffusing species in the plasma; and
exposing the substrate to the plasma to selectively remove the photoresist, polymers, and/or residues from the substrate, wherein the plasma is substantially free from fast diffusing species.
2 . The plasma ashing process of claim 1 , wherein the fast diffusing species have a parabolic rate constant at 270 degrees Celsius of equal to or greater than about 0.02 Angstroms squared per second.
3 . The plasma ashing process of claim 1 , wherein the fast diffusing species comprise O*, O, O + , O − , , H*, or a combination comprising at least one of the foregoing.
4 . The plasma ashing process of claim 1 , wherein suppressing and/or reducing fast diffusing species in the plasma comprises contacting the fast diffusing species with a surface comprising a scavenging material.
5 . The plasma ashing process of claim 4 , further comprising heating the scavenging material to further suppress and/or reduce the fast diffusing species
6 . The plasma ashing process of claim 5 , wherein heating the surface is at a temperature equal to or greater than about 200 degrees Celsius.
7 . The plasma ashing process of claim 5 , wherein the scavenging material has a recombination coefficient of equal to or greater than 5×10 −4 .
8 . The plasma ashing process of claim 5 , wherein the scavenging material is comprises silicon dioxide, aluminum, aluminum oxide, nickel, nickel alloy, platinum, platinum alloy, titanium, titanium oxide, silver, silver alloy, tungsten, tungsten oxide, tungsten alloy, or a combination comprising at least one of the foregoing materials.
9 . The plasma ashing process of claim 1 , wherein the atomic oxygen content is suppressed by the addition of a scavenging gas.
10 . The plasma ashing process of claim 9 , wherein the scavenging gas comprises a NH 3 , CO, NO, or CxHy, wherein the scavenging gas constitutes a sufficient portion of the gas mixture to reduce the atomic oxygen content by a factor of 4 or more.
11 . The plasma ashing process of claim 10 , wherein the gas mixture further comprises a forming gas mixture consisting of hydrogen gas (H 2 ) and nitrogen gas (N 2 ).
12 . The plasma ashing process of claim 1 , wherein the gas mixture further comprises N 2 or N 2 O, wherein the plasma has a ratio of active nitrogen to active oxygen that is larger than a ratio of active nitrogen to active oxygen obtainable from a plasma formed of any oxygen gas and nitrogen gas mixture.
13 . The plasma ashing process of claim 1 , wherein said process includes varying a power density applied to the gas mixture.
14 . The plasma ashing process of claim 13 , wherein said plasma generating step comprises excitation at a power density of at least about 75 watts per centimeter cubed.
15 . The plasma ashing process of claim 13 , wherein said plasma power is from a microwave or RF power source.
16 . A process for ashing organic matter from a substrate, comprising:
generating a plasma from a gas mixture comprising O 2 or oxygen containing gas, wherein the plasma is substantially free from fast diffusing species;
combining the plasma with an atomic oxygen scavenging gas;
exposing the substrate having the organic matter thereon to the plasma; and
selectively removing the organic matter from the substrate.
17 . The process of claim 16 , wherein the scavenging gas reduces an atomic oxygen content in the plasma by a factor of at least about 4.
18 . The process of claim 17 , wherein the scavenging gas comprises NH 3 , CO, CO2, C x H y where x is an integer from 1 to 4, and y is an integer from 1 to 8, or a combination comprising at least one of the foregoing.
19 . The process of claim 18 , wherein a volumetric ratio of the scavenging gas to O 2 is equal to or greater than about 2 to 1.
20 . A plasma apparatus for ashing photoresist, polymers, and/or residues from a substrate, the apparatus comprising:
a plasma generating component for generating a plasma, wherein the plasma is formed from gas mixtures comprising oxygen gas (O 2 ) or an oxygen containing gas, combined with an atomic oxygen scavenging gas;
a scavenging material intermediate the plasma and the substrate configured to suppress and/or reduce fast diffusing species in the plasma; and
a process chamber for housing the substrate in fluid communication with the plasma generating component, said process chamber configured to expose the substrate to the plasma having suppressed and/or reduced fast diffusing species therein to selectively remove photoresist, polymers, and/or residues from the substrate.
21 . The plasma apparatus of claim 20 , wherein the scavenging material comprises silicon dioxide, aluminum, aluminum oxide, nickel, nickel alloy, platinum, platinum alloy, titanium, titanium oxide, silver, silver alloy, tungsten, tungsten oxide, tungsten alloy, or a combination comprising at least one of the foregoing materials.
22 . The plasma apparatus of claim 20 , further comprising an excited-state molecular oxygen gas generated by atomic oxygen recombination.
23 . The plasma apparatus of claim 22 , wherein the generated excited-state molecular oxygen is transported to the wafer within the half-life of the excited-state molecular oxygen.
24 . The plasma apparatus of claim 22 , wherein the generated excited-state molecular oxygen is transported to the wafer within lms.
25 . The plasma apparatus of claim 23 , wherein the generated excited-state molecular oxygen is transported to the wafer by flowing gas in excess of 4 standard-liters per minute.
26 . The plasma apparatus of claim 23 , wherein the scavenging material is disposed about 6 centimeters or less from the substrate.
27 . The plasma apparatus of claim 20 , wherein the gas mixture is excited to form the plasma by either microwave or RF energy at a power density of 75 watts per centimeter cubed or greater.
28 . The plasma apparatus of claim 20 , wherein the scavenging material is heated either directly or indirectly to a temperature of 200° C. or higher.
29 . The plasma apparatus of claim 20 , wherein the scavenging gas is NH 3 , NO, CO, a hydrocarbon gas, or a combination comprising at least one of the foregoing.
30 . The plasma apparatus of claim 20 , wherein the scavenging material is configured to reduce an active oxygen content in the plasma by a factor of at least about 2.