Particle removal method using an aqueous polyphosphate solution
A method and cleaning solution for cleaning electronic substrates, such as a semiconductor wafers, hard disks, photomasks or imprint molds. The method comprises the steps of contacting a surface of the substrate with a cleaning solution comprised of a polyphosphate, and then removing the cleaning solution from the surface. Additional optional steps include applying acoustic energy to the cleaning solution while the cleaning solution is in contact with the surface, and removing the cleaning solution from the surface by rinsing the surface with a rinsing solution with or without the application of acoustic energy. The cleaning solution comprises a polyphosphate, such as any of the water soluble polyphosphates. Depending on the application, the cleaning solution may also comprise a base and/or a quantity of suspended particles. Complexing agents, amines, biocides, surfactants and/or other substances, may also be added to the cleaning solution.
1. A method for cleaning a hard disk comprising:
contacting a surface of a hard disk with a cleaning solution consisting of a polyphosphate, water and a base, the surface of the hard disk having a plurality of submicron particles adhered to the surface; and
removing the cleaning solution from the surface by rinsing the surface with a rinsing solution with the application of acoustic energy to the rinsing solution while the surface is being rinsed with at least some of the submicron particles being carried away from the surface when the cleaning solution is removed from the surface.
2. The method of claim 1 wherein the polyphosphate is a tripolyphosphate.
3. The method of claim 1 wherein the rinsing solution comprises water.
4. The method of claim 1 wherein the, concentration of the polyphosphate is in the range of 0.2% to 15% by weight.
5. The method of claim 1 wherein the base is chosen from the group consisting of KOH, NH 4 OH, TMAH and choline.
6. The method of claim 1 wherein the polyphosphate has the formula
where n =0 to 1000.
7. The method Of claim 1 wherein the water comprises greater than 90.9% of the total volume of the cleaning solution.
8. The method of claim 1 further comprising the steps of:
obtaining a concentrated form of the cleaning solution in which the concentration of the polyphosphate is between 0.5% and 200% by weight in the concentrated form; and
diluting the concentrated form of the cleaning solution before contacting the surface of the hard disk substrate with the cleaning solution.
9. The method of claim 1 further comprising the steps of:
obtaining a concentrated form of the cleaning solution in which the base comprises either NH 4 OH in a concentration of between 1%-28% (by weight of ammonia) or potassium hydroxide in a concentration of between 0.001%-45%; and
diluting the concentrated form of the cleaning solution before contacting the surface of the hard disk substrate with the cleaning solution.
10. The method of claim 1 further comprising:
applying acoustic energy to the cleaning solution while the cleaning solution is in contact with the surface.