Polishing inhibiting layer forming additive, slurry and cmp method

Abstract

A polishing inhibiting layer forming additive for a slurry, the slurry so formed, and a method of chemical mechanical polishing are disclosed. The polishing inhibiting layer is formed through application of the slurry to the surface being polished and is removable at a critical polishing pressure. The polishing inhibiting layer allows recessed or low pattern density locations to be protected until a critical polishing pressure is exceeded based on geometric and planarity considerations, rather than slurry or polishing pad considerations. With the additive, polishing rate is non-linear relative to polishing pressure in a recessed / less pattern dense location. In one embodiment, the additive has a chemical structure: [CH3(CH2)xN(R)]M, wherein M is selected from the group consisting of: Cl, Br and I, x equals an integer between 2 and 24, and the R includes three carbon-based functional groups, each having less than eight carbon atoms.

Description

BACKGROUND OF INVENTION [0001] The present invention relates generally to semiconductor wafer polishing, and more particularly, to a polishing inhibiting layer forming additive for a slurry, the slurry so formed, and a method of chemical mechanical polishing. [0002] In the semiconductor industry, chemical mechanical polishing (CMP) is used to smooth, planarize, and / or remove layers during the fabrication process. During CMP, a slurry is dispersed over the surface to be polished as a polishing pad rotates in contact with the surface to smooth, planarize and / or remove the surface. One problem with conventional CMP processes and slurries is that they do not perfectly planarize a surface, especially those that have a variety of pattern densities or have an uneven topography. For example, FIG. 1 shows an illustrative surface topography of a semiconductor wafer 8 including a raised location A that is higher than a recessed location B. Typically, a polishing rate of a surface is considered...

AI Technical Summary

Benefits of technology

"The invention is about a method and a slurry for chemical mechanical polishing (CMP) that includes a polishing inhibiting layer forming additive. This additive is applied to the surface being polished and helps protect recessed or low pattern density locations until a critical polishing pressure is reached. The polishing inhibiting layer alters the polishing rate-pressure relationship, which results in a non-linear polishing rate relative to pressure. This allows for controlled polishing of different areas of the wafer, improving the overall polishing process. The additive can be a surfactant with a specific chemical structure or a combination of surfactants. The technical effects of this invention include improved polishing efficiency and better surface quality."

Problems solved by technology

One problem with conventional CMP processes and slurries is that they do not perfectly planarize a surface, especially those that have a variety of pattern densities or have an uneven topography.

One factor that causes this problem is slurry above recessed location B still provides a modicum of polishing, which may destroy recessed location B. Another factor is the flexibility of a polishing pad 10, which causes recessed location B to be polished even though not desired.

In this case, however, the surfactant is meant to form a non-removable layer, which does not address the above-described problems.

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