In Situ Stress Measurements During Copper Deposition

Stafford, Gery R.; Beauchamp, Carlos; Kongstein, Ole Edvard

doi:10.1149/1.2408874

Cited by 7 publications

(10 citation statements)

References 23 publications

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“…This third stage is not observed in Fig. 2 but it has been reported by Stafford et al 1,2 at lower concentrations of Cu 2+ (10 -2 mol dm -3 ). We have also observed this third (compressive) stage in the presence of additives as will be discussed later.…”

Section: In-situ Stress Measurements In Additive-free Electrolytementioning

confidence: 43%

“…Stoney's formula 15 relates the force per unit width F/w of the cantilever to its radius of curvature which, in turn, is related to the deflection d of the laser beam at the PSD by the geometry and optics of the system. Based on this, it can be shown 1,2 that…”

Section: Methodsmentioning

confidence: 91%

“…The in-situ stress measurement system is based on a similar apparatus 1,2 developed in Stafford's group at the National Institute for Standards and Technology (NIST). It consists of an electrochemical cell (Starna ® 96/G/20) with a Teflon ® cover which holds a cantilever working electrode (gold-coated glass, see below).…”

Section: Methodsmentioning

confidence: 99%

“…Haiss et al 4 investigated the dependence of stress on overpotential for copper electrodeposition on Au(111) and examined the stress evolution during the first 25 monolayers of deposition. More recently Stafford et al 1,2 extended this work and investigated stress evolution during electrodeposition of copper in sulphate electrolyte from the earliest stages up to 400 nm.…”

Section: Introductionmentioning

confidence: 97%

“…Thin metal films deposited on a substrate are usually in a state of stress and this has been the subject of extensive experimental investigation and theoretical analysis . Various studies [1][2][3][4][5][18][19][20][21][22]27,28 of the stress generated during the electrodeposition and aging of copper films have been reported. Haiss et al 4 investigated the dependence of stress on overpotential for copper electrodeposition on Au(111) and examined the stress evolution during the first 25 monolayers of deposition.…”

Section: Introductionmentioning

confidence: 99%

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Stress and Microstructure in Electrodeposited Copper Nanofilms by Substrate Curvature and In-situ Electrochemical AFM Measurements

Ahmed¹,

Ahmed²,

Grady³

et al. 2008

ECS Trans.

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Both AFM imaging and stress measurements were carried out in-situ during potentiostatic electrodeposition of copper on gold in 0.05 mol dm-3 CuSO4 in 0.1 mol dm-3 H2SO4. In the absence of additives, compressive stress generally developed initially and films subsequently underwent a compressive-to-tensile (C-T) transition. The nucleation density measured by AFM increased from 2.7x107 cm-2 at -75 mV to 2.5x109 cm-2 at -300 mV. Very little coalescence of nuclei was observed at -75 mV but the rate of coalescence increased rapidly with increasing negative potential. The time for the C-T transition correspondingly decreased rapidly until, at -75 mV, none was observed. This is consistent with models that attribute the C-T transition to increasing tensile stress due to coalescence of nuclei. With a combination of Cl-, PEG and MPSA, compressive stress generally developed initially and was greater than in additive-free electrolyte. At less negative potentials, the stress continued to evolve in the compressive direction, even though the rate of coalescence of nuclei was rapid. At intermediate potentials (-90 mV to -150 mV), classical C-T-C behavior was observed; at more negative potentials the stress continued to evolve in the tensile direction. This enhancement of a compressive component of stress is attributed to incorporation of additive-derived impurities.

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Section: In-situ Stress Measurements In Additive-free Electrolytementioning

confidence: 43%

Section: Methodsmentioning

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Stress and Microstructure in Electrodeposited Copper Nanofilms by Substrate Curvature and In-situ Electrochemical AFM Measurements

Ahmed¹,

Ahmed²,

Grady³

et al. 2008

ECS Trans.

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Monitoring and Control

Ritzdorf

2010

Modern Electroplating

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To obtaining quality deposits it is important to monitor and control electrochemical deposition (ECD) processes. This is also essential for an automatic plating system designed to minimize operator attention to production operations. A skilled and knowledgeable operator can maintain a reasonable plating quality with little supporting equipment. However, trends to more automation to reduce costs with higher processing speeds, application of plating to higher value products, and assurance of quality plating make it necessary to utilize many monitoring and control facilities.Electroplating process results are dependent on process stability and control and on the chemical composition of the plating bath. This makes it important to monitor the concentration of the various species in the bath. At a minimum, it is usually important to monitor the concentration of the metal ions and the supporting electrolyte. It may also be necessary to monitor constituents that interact in trace amounts or organic additives that modify the behavior of the process.Electroless plating, as described elsewhere, is an autocatalytic process initiated by a catalyst such as palladium and then catalyzed by the deposited metal itself [1]. Electrochemically, the system is quasi-stable, as it must be to work. This necessitates a closer control of bath chemistry than that required for electroplating solutions. Frequent electroless bath analysis and maintenance are necessary, especially when fast plating is involved, due to the speed with which the chemistry changes. Fast electroless metal deposition or poor bath control can result in spontaneous bath decomposition, causing metal particles to form and strip the solution of all metallic ions. Manual bath sampling and analysis are often not practical. Machines have been developed which automatically take samples and analyze and reconstitute the bath chemistry [2]. These will be discussed in Section 25.2.11. This chapter has three sections: process monitoring, bath constituent concentration monitoring and replenishment, and product monitoring. The first section focuses on sensors and techniques for monitoring the plating and associated processes and how to use these to increase the automation level of plating equipment. Because the concentration monitoring and control of chemistries used in the plating processes are so important and may be handled by equipment separate from the electroplating equipment in some cases, these topics are given their own section. Finally, a short section on product monitoring and quality control is included, although the reader should understand that product monitoring should be dictated more by the product requirements than by the process used to produce it. This section is meant merely as a reference to some of the common monitoring methods in use and how they are applied to control plating processes. PROCESS MONITORINGPlating processes, whether electrolytic or electroless, are utilized for many varied purposes. These may be for the manufacture of simple and cheap parts o...

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Investigation of stress and morphology in electrodeposited copper nanofilms by cantilever beam method and in situ electrochemical atomic force microscopy

Ahmed

O'Grady

et al. 2008

Journal of Applied Physics

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Both stress and atomic force microscopy (AFM) measurements were carried out in situ during potentiostatic electrodeposition of copper on gold in 0.05moldm−3 CuSO4 in 0.1moldm−3 H2SO4 with and without additives. With no additives, compressive stress generally developed initially and films subsequently underwent a compressive-to-tensile (C-T) transition. With increasing negative potential, the time for the C-T transition decreased rapidly as the rate of coalescence of nuclei (measured by AFM) increased rapidly. This is consistent with models that attribute the C-T transition to increasing tensile stress due to coalescence of nuclei. Furthermore, at a potential of −75mV (Cu∕Cu2+), where AFM showed very little coalescence of nuclei, no C-T transition was observed, again consistent with these models. The nucleation density measured by AFM increased from 2.7×107cm−2 at −75mVto2.5×109cm−2 at −300mV. Stress measurements with a combination of three additives [1×10−3moldm−3 Cl−, 8.82×10−5moldm−3 polyethylene glycol, and 1×10−5moldm−3 3-mercapto-1-propanesulfonic acid sodium salt (MPSA)] also showed that compressive stress generally developed initially and its magnitude was greater than in additive-free electrolyte. At less negative potentials, even though the rate of coalescence of nuclei was rapid, as observed by AFM, the stress continued to evolve in the compressive direction. At intermediate potentials (−90to−150mV), classical compressive-tensile-compressive (C-T-C) behavior was observed, while at more negative potentials the stress continued to evolve in the tensile direction. Similar results were obtained with a combination of two additives (1×10−3moldm−3 Cl− and 1×10−5moldm−3 MPSA), but in that case the compressive stress appeared to be greater, and consequently the T-C transition was observed even at −500mV. The results are consistent with enhancement of a compressive component of stress in the presence of additives.

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In Situ Stress Measurements During Copper Deposition

Cited by 7 publications

References 23 publications

Stress and Microstructure in Electrodeposited Copper Nanofilms by Substrate Curvature and In-situ Electrochemical AFM Measurements

Stress and Microstructure in Electrodeposited Copper Nanofilms by Substrate Curvature and In-situ Electrochemical AFM Measurements

Monitoring and Control

Investigation of stress and morphology in electrodeposited copper nanofilms by cantilever beam method and in situ electrochemical atomic force microscopy

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