Composition for tungsten cmp

Abstract

A chemical mechanical polishing composition includes a water based liquid carrier, cationic abrasive particles dispersed in the liquid carrier, a first amino acid compound having an isoelectric point of less than 7 and a second amino acid compound having an isoelectric point of greater than 7. The pH of the composition is in a range from about 1 to about 5. A method for chemical mechanical polishing a substrate including a tungsten layer includes contacting the substrate with the above described polishing composition, moving the polishing composition relative to the substrate, and abrading the substrate to remove a portion of the tungsten from the substrate and thereby polish the substrate.

Description

BACKGROUND OF THE INVENTION[0001]Chemical mechanical polishing (CMP) compositions and methods for polishing (or planarizing) the surface of a substrate are well known in the art. Polishing compositions (also known as polishing slurries, CMP slurries, and CMP compositions) for polishing metal layers (such as tungsten) on a semiconductor substrate may include abrasive particles suspended in an aqueous solution, chemical accelerators such as oxidizers, chelating agents, and the like, and corrosion / etch inhibitors for reducing the rate at which the metal etches in the CMP slurry.[0002]In tungsten plug and interconnect processes, tungsten is generally deposited over a dielectric and within openings formed therein. The excess tungsten over the dielectric layer is then removed during a CMP operation to form tungsten plugs and interconnects within the dielectric. As semiconductor device feature sizes continue to shrink, meeting device requirements including planarity and defect requirements...

AI Technical Summary

Benefits of technology

[0004]A chemical mechanical polishing composition for polishing a substrate having a tungsten layer is disclosed. The polishing composition comprises, consists of, or consists essentially of a water based liquid carrier and cationic abrasive particles dispersed in the liquid carrier. The composition further includes a tungsten corrosion inhibitor having an isoelectric point of less than 7 and a tungsten corrosion inhibitor having an isoelectric point of greater than 7. The pH of the composition is in a range from about 1 to about 5. A method for chemical mechanical polishing a substrate including a tungsten layer is further disclosed. The method may include contacting the substrate with the above described polishing composition, moving the polishing composition relative to the substrate, and abrading the substrate to remove a portion of the tungsten from the substrate and thereby polish the substrate.

Problems solved by technology

As semiconductor device feature sizes continue to shrink, meeting device requirements including planarity and defect requirements has become more difficult in CMP operations such as tungsten CMP operations.

For example, slurry induced defects including excessive localized corrosion can reduce device yields.

Excessive array erosion, localized erosion, and tungsten plug and line recessing, can also compromise overall electrical performance and reduce device yields.

While there are many advantages to the use of hydrogen peroxide, it is known to contribute to excessive tungsten etching in certain CMP operations.

Moreover, as is well known in the art, the semiconductor industry is subject to continuing and severe downward pricing pressure that extends to the CMP consumables themselves (e.g., to the CMP slurries and pads).

Such pricing pressure poses a challenge to the slurry formulator as the pressure to reduce costs often conflicts with the desired slurry performance metrics.