Post metal chemical mechanical polishing dry cleaning
View Patent ↗Metal residue on a semiconductor surface resulting from metal chemical mechanical polishing (“CMP”) process are eradicated using a dry clean process. The dry cleaning uniformly removes or substantially eliminates metal residue from the surface of the semiconductor. An unintended metal short that may be present due to the residue may thereby be eliminated by adjusting the dry cleaning process based on a type of dry cleaning material, and type and a thickness of the residue.
1. A method for dry-cleaning metal residue from a semiconductor surface, comprising:
forming a metal trench pattern in a dielectric layer of a semiconductor device, the metal trench pattern having a conductive metal therein, the metal trench pattern having an edge to edge distance of 150 nm or less, the conductive metal and the dielectric layer defining a semiconductor surface;
preparing the semiconductor surface using a chemical mechanical polish (CMP) process, the metal residue including the conductive metal smeared in an unintended scratch at the semiconductor surface;
exposing the prepared semiconductor surface to a plasma and an inert gas, the plasma having ions reacting with the metal residue to form a volatile gas, the prepared semiconductor surface being exposed to the plasma for a predetermined range of time to directly remove the metal residue from the scratch; and
removing the metal residue in the unintended scratch at the semiconductor surface.
2. The method of claim 1 where the step of preparing the semiconductor surface forms the metal residue in the scratch.
3. The method of claim 1 where the metal trench pattern comprises a metal material selected from the group consisting of tungsten, copper, aluminum, and aluminum alloy.
4. The method of claim 3 where the metal residue comprises the metal material of the metal trench pattern as a consequence of the CMP process.
5. The method of claim 1 where the plasma comprises any one of CF 4 , NF 3 , CHF 3 , C 4 F 6 , Br and Cl.
6. The method of claim 1 where the predetermined range of time of exposure to the plasma is based on the metal residue.
7. The method of claim 1 wherein the dielectric layer is a substrate material comprising any one of a silicon substrate, silicon on insulator substrate, silicon on sapphire substrate, glass substrate, ceramic substrate, gallium arsenide substrate and metallized substrate.
8. The method of claim 1 where the scratch has a depth of less than approximately 10% of a depth of the metal trench pattern.
9. The method of claim 1 where the metal residue in the scratch has a depth of approximately 5 nanometers.
10. A method of dry-cleaning a metal residue-filled scratch in a chemical mechanical polished semiconductor surface, the semiconductor surface defining a metal trench pattern having an edge to edge distance of 150 nm or less, the chemical mechanical polishing of the surface affecting the metal residue-filled scratch, the method comprising:
exposing the surface to a plasma, the plasma reacting with the residue to form a volatile gas, the plasma being diluted with an inert gas and having a pressure substantially in the range of 0.3 Torr, a gas flow rate of approximately 100 sccm and a temperature less than approximately 250° C.
11. The method of claim 10 where the metal trench pattern comprises any one of tungsten, copper, aluminum and aluminum alloy.
12. The method of claim 11 where the plasma comprises any one of CF 4 , NF 3 , CHF 3 , C 4 F 6 , Br and Cl.
13. The method of claim 12 where the surface is exposed to the plasma for approximately 10 seconds.
14. The method of claim 12 where the scratch has a depth of less than 10% of a depth of the metal pattern.