Stress in thermally annealed parylene films

Dabral, S.; Etten, Jaap Van; Zhang, Xinshu; Apblett, Christopher A.; Yang, G.‐R.; Ficalora, P. J.; McDonald, J. F.

doi:10.1007/bf02684208

Cited by 48 publications

(32 citation statements)

References 6 publications

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“…1(c)]. This is followed by a parylene-C deposition with a thickness of [10][11][12][13][14][15][16][17][18][19][20] to refill the trenches [see Fig Clearly, the parylene-C deposition is conformal, and the film thickness is almost uniform even inside the deep trench. This is because the mean free path of parylene molecules is as small as a few cm, and also because the sticking coefficient, which is defined by the ratio between the number of molecules reacting with a radical chain end and the number of incident monomer molecules onto the surface, is as low as at room temperature [28].…”

Section: Fabrication Of Parylene High-aspect-ratio Structuresmentioning

confidence: 99%

“…and 350 in height due to the RIE lag. Parylene film is known to be in compressive stress as it is deposited, but that becomes tensile stress after thermal annealing [13], [14]. In the present study, the parylene film undergoes baking at 100-110 for the lithography step of the etch windows on the backside [see Fig.…”

Section: Fabrication Of Parylene High-aspect-ratio Structuresmentioning

confidence: 99%

“…Parylene (poly-para-xylylene) is known as a MEMS-compatible polymer that can be deposited with a CVD process, and is now attracting increasing attention for possible use in mechanical and fluidic micro devices [5]- [12]. Its physical properties and detailed internal stress characteristics have previously been reported [13], [14]. a small Young's modulus ( ), which makes it easy to design soft springs with.…”

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confidence: 99%

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Micromachined High-Aspect-Ratio Parylene Spring and Its Application to Low-Frequency Accelerometers

Suzuki

Tai

2006

J. Microelectromech. Syst.

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Abstract-A new microfabrication technology for high-aspectratio parylene structure has been developed for soft spring applications. Free-standing parylene beams with widths of 10-40 m and aspect ratios of 10-20 have been successfully fabricated. Since parylene has a small Young's modulus, a high-aspect-ratio beam with a spring constant of the order of 1 10 3 N m has been realized. The large yield strain of parylene enables a test structure to have a large-amplitude oscillation of 600 m p-p , without any failure of the high-aspect-ratio springs. An early prototype of in-plane capacitive accelerometer was also developed. It was found that its resonant frequency is as low as 37 Hz, and the noise spectral density is 64 g (Hz) 0 5 .[1606]Index Terms-Capacitive accelerometer, high-aspect-ratio beam, low spring constant, parylene.

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Section: Fabrication Of Parylene High-aspect-ratio Structuresmentioning

confidence: 99%

Section: Fabrication Of Parylene High-aspect-ratio Structuresmentioning

confidence: 99%

mentioning

confidence: 99%

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Micromachined High-Aspect-Ratio Parylene Spring and Its Application to Low-Frequency Accelerometers

Suzuki

Tai

2006

J. Microelectromech. Syst.

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“…Depositing metal on only one side of the Parylene would also make the device prone to curling due to residual stresses in the various layers, which have been measured as 22 MPa (Dabral et al, 1992;Harder et al, 2002), 230 MPa (Branger et al, 1996), and 383 MPa (Tripp et al, 2006), for Parylene, platinum, and Al2O3, respectively. Curling was not observed on our devices because the sandwich structure caused the residual stress in the two layers to cancel out (Branger et al, 1996).…”

Section: Minimum Bending Diametermentioning

confidence: 99%

Mechanical Properties of Thin-Film Parylene–Metal–Parylene Devices

Lee

Meng

2015

Front. Mech. Eng.

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Structures and testing methods for measuring the adhesion strength, minimum bending diameter, and bending fatigue performance of thin-film polymer electronic architectures were developed and applied to Parylene-metal-Parylene systems with and without the moisture barrier Al2O3 [deposited using atomic layer deposition (ALD)]. Parylene-metalParylene interfaces had the strongest average peel test strength and Parylene-Parylene interfaces had the weakest peel test strength. Layers of ALD Al2O3 deposited within the device increased the average peel strength for Parylene-Parylene interfaces when combined with silane A-174, but did not increase that of the Parylene-metal-Parylene interface. Metal traces in the middle of 24 μm thick Parylene-metal-Parylene devices had a minimum bending diameter of ~130 μm before breaking and being measured as an open circuit. The addition of one layer of Al2O3 above the traces allowed them to be completely creased when bent away from the Al2O3 layer without producing an open circuit, but increased the minimum bending diameter to ~450 μm when bent towards the Al2O3. Although fatigue testing produced cracks in all devices after 100k bends, the insulation of the Parylene-metal-Parylene devices without Al2O3 performed well with electrochemical impedance spectroscopy showing only small decreases in impedance magnitude and small increases of impedance phase at low frequencies. However, devices with Al2O3 failed during EIS due to Al2O3 being deteriorated by water.

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“…The check valve is thermally annealed at predetermined temperature after the sacrificial photoresist is released and quenched down afterwards. Since the residual tensile stress of the thermally annealed parylene C can be as high as 34 MPa at 250°C [5], this approach allows the parylene tethers to provide a high downward force while it does not require any post-fabrication fixation. …”

Section: Introductionmentioning

confidence: 99%

Cracking pressure control of parylene checkvalve using slanted tensile tethers

Lin

Tai

2010

2010 IEEE 23rd International Conference on Micro Electro Mechanical Systems (MEMS)

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MEMS check valves with fixed cracking pressures are important in micro-fluidic applications where the pressure, flow directions and flow rates all need to be carefully controlled. This work presents a new surface-micromachined parylene check valve that uses residual thermal stress in the parylene to control its cracking pressure. The new check valve uses slanted tethers to allow the parylene tensile stress to apply a net downward force on the valving seat against the orifice. The angle of the slanted tethers is made using a gray-scale mask to create a sloped sacrificial photoresist with the following tether parylene deposition. The resulted check valves have both the cracking pressures and flow profiles agreeable well with our theoretical analysis.

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Stress in thermally annealed parylene films

Cited by 48 publications

References 6 publications

Micromachined High-Aspect-Ratio Parylene Spring and Its Application to Low-Frequency Accelerometers

Micromachined High-Aspect-Ratio Parylene Spring and Its Application to Low-Frequency Accelerometers

Mechanical Properties of Thin-Film Parylene–Metal–Parylene Devices

Cracking pressure control of parylene checkvalve using slanted tensile tethers

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