A simple model for the formation of compressive stress in thin films by ion bombardment

Davis, C. A.

doi:10.1016/0040-6090(93)90201-y

Cited by 775 publications

(250 citation statements)

References 14 publications

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“…energetic ions can be used for this purpose since they can trigger surface and bulk diffusion processes, 1,102 induce changes in the film structure and chemical composition, 103 and cause generation of internal stresses. [104][105][106][107] The high fluxes of ionized material available in HiPIMS have been found to allow for control of the phase formation in both elemental and compound films. One example is the control of the phase composition in Ta films.…”

Section: B Phase Composition Tailoring By Hipimsmentioning

confidence: 99%

An introduction to thin film processing using high-power impulse magnetron sputtering

2012

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High-power impulse magnetron sputtering (HiPIMS) is a promising sputtering-based ionized physical vapor deposition technique and is already making its way to industrial applications. The major difference between HiPIMS and conventional magnetron sputtering processes is the mode of operation. In HiPIMS the power is applied to the magnetron (target) in unipolar pulses at a low duty factor (andlt;10%) and low frequency (andlt;10 kHz) leading to peak target power densities of the order of several kilowatts per square centimeter while keeping the average target power density low enough to avoid magnetron overheating and target melting. These conditions result in the generation of a highly dense plasma discharge, where a large fraction of the sputtered material is ionized and thereby providing new and added means for the synthesis of tailor-made thin films. In this review, the features distinguishing HiPIMS from other deposition methods will be addressed in detail along with how they influence the deposition conditions, such as the plasma parameters and the sputtered material, as well as the resulting thin film properties, such as microstructure, phase formation, and chemical composition. General trends will be established in conjunction to industrially relevant material systems to present this emerging technology to the interested reader.Funding Agencies|Swedish Research Council (VR)|623-2009-7348

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Section: B Phase Composition Tailoring By Hipimsmentioning

confidence: 99%

An introduction to thin film processing using high-power impulse magnetron sputtering

2012

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“…Ar + experiments on amorphous carbon for energies down to the 50 eV-1 keV range [36], it is believed that processes at these energies are described better by a binary-collision picture [4]. Still, as shown in [37], detailed binary-collision simulations lead to an energy dependence of the generated stress that cannot be distinguished from that in [35] for energies below 2 keV. We employ the latter for analytical convenience leading, for the energy range in our experiments, to [31] f E =E -7/6-2m , where we assume that the thickness of the amorphous layer also scales with energy, as d = E 2m , typical values of m being between 1/3 and 1/2 as determined from TRIM [38].…”

Section: Ion-induced Solid Flowmentioning

confidence: 99%

“…This stress depends on ion energy, following a square-root law that is modified if one takes into account the partial stress relaxation occurring in a time scale comparable to the one needed for collision cascades to relax, in turn orders of magnitude faster than those associated with viscous flow. Davis [35] assumed spike formation to allow displaced atoms to move to the free surface and decrease the effective stress generation. Although spike formation has been shown to account for e.g.…”

Section: Ion-induced Solid Flowmentioning

confidence: 99%

Energy dependence of the ripple wavelength for ion-beam sputtering of silicon: Experiments and theory

Castro¹,

Gago²,

Vázquez³

et al. 2013

AIP Conference Proceedings

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Abstract. In spite of the efforts devoted for the last 20 years to elucidating ion-beam sputtering (IBS) as an instance of surface self-organization, the classic view on the main mechanism inducing the morphological instability has been recently challenged. We report on the verification of a recent theoretical description of this nanopattern formation process for semiconducting targets, as driven by stress-induced, viscous flow of a thin amorphous layer that develops at the surface [M. Cuerno and R. Cuerno, Appl. Surf. Sci. 258, 4171 (2012)]. Through experiments on silicon as a representative case, we study the dependence of the ripple wavelength with the average ion energy, finding a linear dependence in the 0.3-1 keV range. This is explained within the viscous flow framework, taking into account the energy dependence of the number of displaced atoms generated by collision cascades in the amorphous layer, as predicted by previous models of ion-generated stress. For our analysis, we provide a systematic criterion to guarantee actual linear dynamics behavior, not affected by the onset of nonlinear effects that may influence the value of the ripple wavelength.

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“…The direct relationship between compressive (bulk-implantation process) stress and ion momentum in sputtered films has been modeled theoretically by Davis, 26 yielding a proportionality of…”

Section: Implantation Effects On Stressmentioning

confidence: 99%

“…Intrinsic stress in amorphous silicon thin films can be viewed as a balance between two distinct but competing forces: the collapse of hydrogenated nanovoids after being formed on the depositing layer creating tensile stress, 24,25 and lattice expansion effects, which are responsible for the creation of compressive stresses in the film through the implantation of ions into the previously deposited layers 26 (often referred to as "ion peening"). While plasma ion momentum dictates both of these forces, it is their relative strength at any given momentum level that determines the net intrinsic stress state of the film.…”

Section: A Origins Of Stressmentioning

confidence: 99%

Structural origins of intrinsic stress in amorphous silicon thin films

et al. 2012

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Hydrogenated amorphous silicon (a-Si:H) refers to a broad class of atomic configurations, sharing a lack of long-range order, but varying significantly in material properties including optical constants, porosity, hydrogen content, and intrinsic stress. It has long been known that deposition conditions affect microstructure, but much work remains to uncover the correlation between these parameters and their influence on electrical, mechanical, and optical properties critical for high-performance a-Si:H photovoltaic devices. We synthesize and augment several previous models of deposition phenomena and ion bombardment, developing a refined model correlating plasma enhanced chemical vapor deposition (PECVD) conditions (pressure and discharge power and frequency) to the development of intrinsic stress in thin films. As predicted by the model presented herein, we observe that film compressive stress varies nearly linearly with bombarding ion momentum and with a (-1/4) power dependence on deposition pressure, that tensile stress is proportional to a reduction in film porosity, and the net film intrinsic stress results from a balance between these two forces. We observe the hydrogen bonding configuration to evolve with increasing ion momentum, shifting from a voiddominated configuration to a silicon monohydride configuration. Through this enhanced understanding of the structure-property-process relation of a-Si:H films, improved tunability of optical, mechanical, structural, and electronic properties should be achievable.

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A simple model for the formation of compressive stress in thin films by ion bombardment

Cited by 775 publications

References 14 publications

An introduction to thin film processing using high-power impulse magnetron sputtering

An introduction to thin film processing using high-power impulse magnetron sputtering

Energy dependence of the ripple wavelength for ion-beam sputtering of silicon: Experiments and theory

Structural origins of intrinsic stress in amorphous silicon thin films

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