Ultra-sensitive, highly reproducible film stress characterization using flexible suspended thin silicon plates and local curvature measurements

Tang, Yu; Chen, Jing; Huang, Yu Bo; Li, Da Chao; Wang, Sha Sha; Li, Zhi Hong; Zhang, Wen Dong

doi:10.1088/0960-1317/17/10/001

Cited by 12 publications

(8 citation statements)

References 18 publications

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“…[72][73][74] A comparison of Young's modulus E and the Poisson's ratio 68 of several materials frequently used in flexible electronics [e.g., singlecrystal Si, hydrogenated amorphous (a-Si:H), hydrogenated nanocrystalline Si (nc-Si:H), polycrystalline Si, Kapton V R , and polyethylene naphthalate (PEN)] is given in Table I. [75][76][77][78][79][80][81][82] The experimental techniques that have been used to study mechanical aspects of UTCs include (i) direct methods 83,84 such as xray diffraction 85,86 and micro-Raman spectroscopy 87,88 and (ii) indirect methods based on measuring the curvature 89 (e.g., optical interferometry, 90 laser scanning, 91,92 and microscope image monitoring in real time 43 ). The subsection below presents the uniaxial and biaxial bending in UTCs.…”

Section: Ultra-thin Chips and Mechanical Bendingmentioning

confidence: 99%

Bending induced electrical response variations in ultra-thin flexible chips and device modeling

Heidari

Wacker

Dahiya

2017

Applied Physics Reviews

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Electronics that conform to 3D surfaces are attracting wider attention from both academia and industry. The research in the field has, thus far, focused primarily on showcasing the efficacy of various materials and fabrication methods for electronic/sensing devices on flexible substrates. As the device response changes are bound to change with stresses induced by bending, the next step will be to develop the capacity to predict the response of flexible systems under various bending conditions. This paper comprehensively reviews the effects of bending on the response of devices on ultra-thin chips in terms of variations in electrical parameters such as mobility, threshold voltage, and device performance (static and dynamic). The discussion also includes variations in the device response due to crystal orientation, applied mechanics, band structure, and fabrication processes. Further, strategies for compensating or minimizing these bending-induced variations have been presented. Following the in-depth analysis, this paper proposes new mathematical relations to simulate and predict the device response under various bending conditions. These mathematical relations have also been used to develop new compact models that have been verified by comparing simulation results with the experimental values reported in the recent literature. These advances will enable next generation computer-aided-design tools to meet the future design needs in flexible electronics.

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Section: Ultra-thin Chips and Mechanical Bendingmentioning

confidence: 99%

Bending induced electrical response variations in ultra-thin flexible chips and device modeling

Heidari

Wacker

Dahiya

2017

Applied Physics Reviews

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“…18,19 Though the measurement is straightforward, this technique is limited by its sensitivity for resolving small changes in curvature. 20 Hence, this technique becomes markedly less reliable as films become increasingly thin and deformations become very small. The sensitivity can be enhanced when applied to thinner substrates; however, wafers with a thickness below 100 m are fragile and require special handling.…”

mentioning

confidence: 99%

“…The sensitivity can be enhanced when applied to thinner substrates; however, wafers with a thickness below 100 m are fragile and require special handling. 20 Therefore, there is a measurement need for accurately quantifying residual stress in polymer thin films. Additionally, this metrology can improve the understanding and control of residual stress in order to optimize the performance of polymer coatings used in numerous nanoscale device applications such as next-generation lithography, organic electronics, and sensors.…”

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confidence: 99%

Quantifying Residual Stress in Nanoscale Thin Polymer Films via Surface Wrinkling

et al. 2009

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Residual stress, a pervasive consequence of solid materials processing, is stress that remains in a material after external forces have been removed. In polymeric materials, residual stress results from processes, such as film formation, that force and then trap polymer chains into nonequilibrium stressed conformations. In solvent-cast films, which are central to a wide range of technologies, residual stress can cause detrimental effects, including microscopic defect formation and macroscopic dimensional changes. Since residual stress is difficult to measure accurately, particularly in nanoscale thin polymer films, it remains a challenge to understand and control. We present here a quantitative method of assessing residual stress in polymer thin films by monitoring the onset of strain-induced wrinkling instabilities. Using this approach, we show that thin (>100 nm) polystyrene films prepared via spin-coating possess residual stresses of approximately 30 MPa, close to the crazing and yield stress. In contrast to conventional stress measurement techniques such as wafer curvature, our technique has the resolution to measure residual stress in films as thin as 25 nm. Furthermore, we measure the dissipation of residual stress through two relaxation mechanisms: thermal annealing and plasticizer addition. In quantifying the amount of residual stress in these films, we find that the residual stress gradually decreases with increasing annealing time and plasticizer amounts. Our robust and simple route to measure residual stress adds a key component to the understanding of polymer thin film behavior and will enable identification of more effective processing routes that mitigate the detrimental effects of residual stress.

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“…Small membranes are used in different applications (e.g. as sensor or part of MEMS) which during manufacturing acquire certain level of tension that deviates their expected behaviour form [23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Study of the Dynamic Behaviour of Circular Membranes with Low Tension

2019

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The dynamic behaviour of membranes has been widely studied by well-known authors for a long time. A clear distinction can be made between the behaviour of membranes without tension (plate case) and membranes subjected to large tension or pre-strain in their plane (membrane case). In classical theories, less attention has been paid to membranes subjected to a low level of tension, which solution is between both extreme cases. Recently, certain fields of research are demanding solutions for this intermediate behaviour. It is the case of membranes present in MEMS and sensor or the response of the tympanic membrane in mammals hearing system. In this paper, the behaviour of plates and circular membranes with boundary conditions clamped in the edges has been studied. The natural frequencies for both cases (plate and membrane) have been calculated using the solutions of the traditional theories and these have been compared with the numerical frequencies calculated by finite element analysis. The dynamic response of membrane with low tension, corresponding to a transition between these extreme behaviours, has also been calculated. A theoretical solution has been used complemented with a wide set of numerical finite elements calculations. The analytical and numerical solutions are very close, being the error made using both methods very low; nevertheless, there are no analytical solutions for the entire transition zone between the plate and membrane behaviour. Therefore, this range has been completed using finite element analysis. Broad ranges of geometric configurations have been studied. The transition behaviour of the membrane has been clearly identified. The main practical consequences of these results have been discussed, in particular focused on the response of the tympanic membrane.

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Ultra-sensitive, highly reproducible film stress characterization using flexible suspended thin silicon plates and local curvature measurements

Cited by 12 publications

References 18 publications

Bending induced electrical response variations in ultra-thin flexible chips and device modeling

Bending induced electrical response variations in ultra-thin flexible chips and device modeling

Quantifying Residual Stress in Nanoscale Thin Polymer Films via Surface Wrinkling

Study of the Dynamic Behaviour of Circular Membranes with Low Tension

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