Polishing of hard substrates with soft-core composite particles
A chemical mechanical polishing (CMP) includes providing a slurry including composite particles dispersed in a water-based carrier that comprise a plurality of hard particles on an outer surface of a soft-core particle. The hard particles have a Mohs hardness at least 1 greater than a Mohs hardness of the soft core particle and/or a Vickers hardness at least 500 Kg/mm 2 greater than the soft-core particle. A substrate having a substrate surface with a hardness greater than a Mohs number of 6 or a Vickers hardness greater than 1,000 kg/mm 2 is placed into a CMP apparatus having a rotating polishing pad, and CMP is performed with the rotating polishing pad and the slurry to polish the substrate surface.
1. A method of chemical mechanical polishing (CMP), comprising
providing a slurry
comprising a plurality of composite particles dispersed in a water-based carrier that comprise a plurality of hard diamond particles on an outer surface of a soft-core particle comprising an inorganic material wherein said soft-core particle comprise alumina, boron carbide, boron nitride, or silicon carbide, and wherein an average size of said soft-core particle is at least 1 μm
placing a substrate having a substrate surface with a hardness greater than a Mohs number of 6 or a Vickers hardness greater than 1,000 kg/mm into a CMP apparatus having a rotating polishing pad, and
performing CMP with said rotating polishing pad and said slurry to polish said substrate surface.
2. The method of claim 1 , wherein said substrate surface comprises sapphire, single crystal SiC, or single crystal GaN.
3. The method of claim 1 , wherein said slurry has a pH between 9 and 14.0 or said slurry has a pH between 0.01 and 4.
4. The method of claim 1 , wherein said slurry further comprises alkali ions in a concentration between 0.01 gm/liter and 200 gm/liter.
5. The method of claim 1 , wherein said slurry further comprises at least one oxidizer and at least one surfactant.
6. A chemical mechanical polishing (CMP) slurry, comprising:
a plurality of composite particles dispersed in a water-based carrier that comprise a plurality of diamond particles on an outer surface of a soft-core particle comprising an inorganic material,
and
wherein said soft-core particle comprise alumina, boron carbide, boron nitride, or silicon carbide, and
wherein an average size of said soft-core particle is at least 1 μm.
7. The slurry of claim 6 , wherein at least one of said plurality of diamond particles and said soft-core particle include a metallic oxide compound coating thereon.
8. The slurry of claim 6 , wherein said slurry has a pH between 9 and 14 or said slurry has a pH between 0.01 and 4.
9. The slurry of claim 6 , wherein said slurry further comprises alkali ions in a concentration between 0.01 gm/liter and 200 gm/liter.
10. The slurry of claim 6 , wherein said slurry further comprises at least one oxidizer and at least one surfactant.
11. The slurry of claim 10 , wherein said oxidizer comprises a per-based compound, and wherein said plurality of diamond particles have an average size <1 μm, and a pH of said slurry is <7.0.
12. The slurry of claim 6 , wherein said soft-core particle comprises alumina.
13. The slurry of claim 7 , wherein both said plurality of diamond particles and said soft-core particle include said metallic oxide compound coating thereon.