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Ru and O2 ALD Process with Hydrocarbon Deactivation Step

IP.com Disclosure Number: IPCOM000217144D
Publication Date: 2012-May-04
Document File: 9 page(s) / 374K

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The IP.com Prior Art Database

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John D. Peck: AUTHOR [+2]

Abstract

Improved nucleation density during the ALD of Ru films using ECPR was accomplished by the addition of a deactivating reagent (in this case 1,4-cyclooctadiene) after the oxygen pulse/purge step. Comparison of the films by SEM analysis demonstrated that processes using a deactivating agent such as 1,5-cyclooctadiene, resulted in increased nucleation density, compared to the processes without a deactivating agent. Specifically, the ruthenium nuclei yielded by the process using 1,5-cyclooctadiene as a deactivating agent were smaller by about 50% and the nucleation density was approximately doubled, compared to the process without the use of 1,5 cyclooctadiene.

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Ru and O2 ALD Process with Hydrocarbon Deactivation Step

John D. Peck and Ronald F. Spohn

Praxair, Inc.

Improved nucleation density during the ALD of Ru films using ECPR was accomplished by the addition of a deactivating reagent (in this case 1,4-cyclooctadiene) after the oxygen pulse/purge step. Comparison of the films by SEM analysis demonstrated that processes using a deactivating agent such as 1,5-cyclooctadiene, resulted in increased nucleation density, compared to the processes without a deactivating agent. Specifically, the ruthenium nuclei yielded by the process using 1,5-cyclooctadiene as a deactivating agent were smaller by about 50% and the nucleation density was approximately doubled, compared to the process without the use of 1,5-cyclooctadiene.

Introduction

Ruthenium is currently being evaluated for several semiconductor applications, including use as a capacitor electrode in next-generation DRAM devices. For a capacitor electrode application, the thin-film deposition technique must provide good conformality on three-dimensional features with high aspect ratios. As a result, atomic layer deposition (ALD) of ruthenium is being examined.

Ruthenium is attractive for a number of reasons, including low resistivity and good compatibility with next-generation high  materials (e.g., strontium titanate; Lee, S.; et. al. ECS Transactions (2007), 6 (3), 87; Srinivasan, B; et. al. US 20100258903). Very low film thickness is required due to the limited amount of space available, at aggressively scaled device dimensions. The minimum thickness of a continuous polycrystalline film is determined by its nucleation density, hence high nucleation density is of prime importance.

Atomic layer deposition (ALD) methods offer many advantages over the traditional deposition methods (George, S.M. Chem. Rev. 2010, 110, 111). ALD relies on self-limiting surface reactions in order to provide accurate thickness control, excellent conformality, and uniformity over large areas. As the microscopic features on a chip grow increasingly narrow and deep, these unique features make ALD one of the most promising deposition methods in the manufacturing of future circuits. The feature that makes ALD a unique deposition method compared to other methods is that it deposits atoms or molecules on a wafer a single layer at a time.

ALD accomplishes deposition by introducing gaseous precursors alternately onto a work piece such as, for example, semiconductor substrate or wafer. Typically, ALD processes involve a sequence of steps. These steps usually occur by the introduction of various gases into a deposition chamber. The work piece may be at ambient temperature or heated or cooled to aid in the adsorption and/or decomposition of the gases. The gas streams can contain inerts, such as nitrogen or argon, precursors either neat or diluted in an inert gas, or a reactant to decompose the precursor to produce a thin film. The steps include 1) adsorption of a precurs...