Water-jet-assisted diamond disk dressing characteristics of CMP polishing pad

Abstract

This paper presents an experimental investigation of the dressing characteristics of a porous polishing pad using a combination of water-jet dressing (WJC) and traditional diamond disk dressing (DDC). The WJC and DDC dressing mechanisms were integrated in order to improve the dressing efficiency. The pad recovery test was performed. In this test, the real-time friction force was determined, scanning electron microscope images were obtained, and the dressed surface topography after prolonged operation without conditioning was examined. The pad cut rate and the rate of removal of the copper substrate by the polishing process were investigated by comparing the results of the WJC + DDC, only DDC, and only WJC methods. The experimental results showed that although the WJC can remove the slurry residue from the pad surface and consumes less pad material, it cannot remove the glazed layer formed as a result of plastic deformation, which contributes to the low material removal rate. On the other hand, DDC can remove the glazed layer of the pad and restore the pad asperities; however, a few residual chips still remain on the sides of the pores or inside the pores. WJC + DDC cannot only remove the embedded slurry particulates and the glazed layer, but also remove the slurry residue accumulated on the pad surface and restore the pad asperities. In addition, the chip residues in the pores, created by the diamond grit, are completely removed by the WJC + DDC conditioning process; the removal of the chip residue helps in obtaining the highest material removal rate. In summary, WJC + DDC can be used as an effective pad conditioning method.