Nodule ratios for targeted enhanced cleaning performance
A foam brush that has nodules on an outer diameter surface of the brush that have a pitch to diameter ratio (P/D) of between 1.2 and 1.5 and a nodule height to nodule diameter ratio of 0.2 to 0.5 can be used to achieve improved small particle and organic residue removal from substrates following CMP processing. CMP cleaning brushes of the disclosure may also be prepared with foams that are relatively soft and have a compression strength of less than 90 grams/cm 2 . CMP cleaning brushes with such P/D and H/D ratios, and optionally a compression strength of less than 90 grams/cm 2 can be used in a variety of CMP cleaning processes including post copper CMP processes.
1. A brush for cleaning wafers after a CMP process, wherein the brush is formed from a foam material and wherein the brush is cylindrical comprising a base with a rotational axis and a plurality of uniformly shaped and spaced nodules extending outwardly from the base, each nodule having a center, a nodule height, and a nodule diameter, the brush nodules having an average nodule pitch to nodule diameter ratio (P/D) of between 1.2 and 1.5 and a nodule height to nodule diameter ratio (H/D) of 0.2 to 0.5,
wherein the nodule height of each nodule is in a range of from 6 mm to 7.5 mm, the nodule diameter of each nodule is in a range of from 12 mm to 15 mm, and the nodule pitch measured from the center of adjacent nodules is in a range of from 17.4 mm and 21.75 mm.
2. The brush as in claim 1 , where the compression strength of the brush foam is less than 90 g/cm 2 .
3. The brush of claim 1 , where the compression strength of the brush foam is between 60 grams/centimeter squared and 90 g/cm 2 .
4. The brush of claim 1 , wherein the foam material is comprised of one of polyvinyl alcohol, polyvinyl acetal, and polyurethane.
5. The brush of claim 1 , wherein each nodule is substantially cylindrically shaped.
6. The brush of claim 1 , wherein the brush has two ends and at least one of the two ends comprises a circumferential row of elongate nodules.
7. The brush of claim 1 , wherein a plane perpendicular to the rotational axis of the brush divides the brush into a first side and a second side, and wherein the nodule configuration on the first side of the brush is different from the nodule configuration on the second side of the brush.
8. The brush of claim 1 , wherein the outside diameter of the brush is from 40 mm to 70 mm.