Planarization with suspended polyurethane beads and a stiff counterface: Pad-in-a-bottle experiments and simulation

An alternative to conventional CMP termed “pad-in-a-bottle” (PIB) polishing is reported, in which the polyurethane polishing pad is replaced by a stiff polycarbonate counterface, and polyurethane beads 10-50 μm in diameter are used in conjunction with slurry and slurry particles to achieve planarization. Blanket oxide wafer PIB experiments demonstrate effective oxide removal. Patterned wafer PIB experiments show improved dishing in STI test wafers. A new dual-material PIB model has been developed and fit to the experimental data. Exploratory simulations show that the primary source of reduced pattern dependent dishing is the use of the stiff counterface as enabled by the compliant beads.