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Mixed abrasive tungsten cmp composition

a technology of tungsten and tungsten, which is applied in the direction of electrical equipment, chemistry equipment and processes, other chemical processes, etc., can solve the problems of compromising planarity and overall device integrity, degrading electrical performance, and unable to meet local and global planarity requirements

Active Publication Date: 2015-09-24
CMC MATERIALS INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The patent describes a chemical mechanical polishing composition for polishing substrates with tungsten layers. The composition includes water-based liquid carrier and two types of silica abrasives: a positively charged colloidal silica abrasive and a neutral / non-positively charged silica abrasive. The composition has an acid pH and may also contain an iron-containing accelerator. The patent also describes a method for polishing substrates with tungsten layers by contacting them with the polishing composition, moving it relative to the substrate, and abrading the substrate to remove tungsten and polish it. The technical effect of the invention is to provide a polishing composition that can efficiently polish substrates with tungsten layers.

Problems solved by technology

As semiconductor device feature sizes continue to shrink, meeting local and global planarity requirements has become more difficult in CMP operations (e.g., in tungsten CMP operations).
Array erosion (also referred to as oxide erosion), plug and line recessing, and tungsten etching defects are known to compromise planarity and overall device integrity.
For example, excessive array erosion may lead to difficulties in subsequent lithography steps as well as cause electrical contact problems that can degrade electrical performance.
The semiconductor industry is also subject to continuing downward pricing pressure.
Such pricing pressure poses a challenge to the slurry formulator as the pressure to reduce costs often conflicts with desired slurry performance metrics.

Method used

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  • Mixed abrasive tungsten cmp composition

Examples

Experimental program
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Effect test

example 1

[0056]In the Examples disclosed herein, mixed silica abrasive polishing compositions were prepared using first and second silica abrasives selected from nine silica abrasive dispersions. Dispersions A1, B1, C1, and D1 included colloidal silica dispersions treated with an aminosilane (aminopropyl trialkoxysilane) such that the colloidal silica particles had a permanent positive charge of greater than 10 mV. Dispersions A2, B2, C2, and D2 included colloidal silica particles dispersed in an aqueous solution. The colloidal silica abrasives in A1, A2, B1, B2, C1, C2, D1, and D2 each contained a partially aggregated silica abrasive in which 50 percent or more of the colloidal silica abrasive particles include two aggregated primary particles. Dispersion F2 included an untreated fumed silica having a surface area of about 150 m2 / g which was dispersed in an aqueous solution. Further details regarding these nine silica abrasive dispersions are presented in Table 1. The primary particle sizes...

example 2

[0057]The tungsten (W) polishing rate was evaluated in this example for various polishing compositions, each of which included first and second silica abrasives selected from dispersions A1, B1, C1, and D1 in Example 1. The first and second silica abrasives in this example each included a colloidal silica having a permanent positive charge of greater than 10 mV. This example demonstrates the effects of the relative amounts of the first and second silica abrasives and the particle sizes of the first and second silica abrasives on the W polishing rate. Each of the polishing compositions had a pH of about 2.5 and included 0.031 weight percent ferric nitrate nonahydrate (Fe(NO3)3.9H2O), 0.04 weight percent malonic acid, and 2.4 weight percent hydrogen peroxide. The W polishing rates were obtained by polishing eight inch blanket wafers having a W layer using a Mirra® CMP tool (available from Applied Materials) and an IC1010 polishing pad at down-force of 2.5 psi, a platen speed of 103 rp...

example 3

[0059]The tungsten (W) polishing rate was evaluated in this example for various polishing compositions, each of which included first and second silica abrasives selected from dispersions A1, B1, C1, and D1 in Example 1. The first and second silica abrasives in this example each included a colloidal silica having a permanent positive charge of greater than 10 mV. This example also demonstrates the effects of the relative amounts of the first and second silica abrasives and the particle sizes of the first and second silica abrasives on the W polishing rate. Each of the polishing compositions had a pH of about 2.5 and included 0.031 weight percent ferric nitrate nonahydrate, 0.04 weight percent malonic acid, and 2.4 weight percent hydrogen peroxide. The W polishing rates were obtained by polishing eight inch blanket wafers having a W layer using a Mirra® CMP tool (available from Applied Materials) and an IC1010 polishing pad at down-force of 2.5 psi, a platen speed of 103 rpm, a head s...

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Abstract

A chemical mechanical polishing composition includes a water based liquid carrier and first and second silica abrasives dispersed in the liquid carrier. The first silica abrasive is a colloidal silica abrasive having a permanent positive charge of at least 10 mV. The second silica abrasive has a neutral charge or a non-permanent positive charge. 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 and chemical accelerators such as oxidizers, chelating agents, catalysts, and the like.[0002]In a conventional CMP operation, the substrate (wafer) to be polished is mounted on a carrier (polishing head) which is in turn mounted on a carrier assembly and positioned in contact with a polishing pad in a CMP apparatus (polishing tool). The carrier assembly provides a controllable pressure to the substrate, pressing the substrate against the polishing pad. The substrate and pad are moved relative to one another by an external driving force. The relative motion of the substrate and p...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C09G1/02H01L21/321
CPCH01L21/3212C09G1/02C09K3/1436C09K3/1463C09K3/1409C23F11/141C23F11/18H01L21/30625H01L21/304
Inventor GRUMBINE, STEVENDYSARD, JEFFREY
Owner CMC MATERIALS INC
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