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ased on the assignments in Figure 8.3 and the high resolution scans of the W4f peaks obtained during each analysis. The primary conclusions that may be drawn from XPS analysis are that 1) tungsten is probably present as a mixed oxynitride, and the tungsten spectrum indicates a shift toward increasing oxidation of the film with time. W5P 3/2 WO 2 or WN W5P 3/2 WO 3 Fig. 8.3 Peak deconvolution and chemical assignments from the W 4F high resolution XPS spectra. Composition (Relative %) 65 60 55 50 45 40 W4f7/2 WO 3 W4f5/2 WO 3 Fig. 8.4 Variation in the oxidation state of tungsten as a function of time after selective tungsten deposition. The friction coefficient as a function of oscillatory cycles in the MEMS sidewall tribometer is shown in Figure 8.5. The variation in friction for a perfluorodecytrichlorosilanecoated device tested under similar conditions is also shown for comparison. The tungsten coated device operating in air exhibits a friction coefficient of 0.06 for the test duration of 300,000 cycles. Under the same conditions, silane coated devices exhibit highly variable friction response, with the friction coefficient ocasionally exceeding 0.2. At slightly over 100,000 cycles, this device becomes stuck and must be released by removing the load on the loading 78 W4f 7/2 WO 2 or WN WO 3 WO 2 or WN W4f 5/2 WO 2 or WN 35 0 2 4 6 8 10 12 14 Time (days)
actuator. After unloading, the device began to slide again with irratic friction behavior. These trends in friction evolution can be understood by examining the wear surface morphologies of both devices. Friction Coefficient 0.6 0.5 0.4 0.3 0.2 0.1 0.0 10 2 W coated PFTS coated 10 3 10 4 Cycles Fig. 8.5 Friction coefficient versus oscillatory cycles (12 µm amplitude of sliding) for selective tungsten coated MEMS sidewall tribometer, and a polycrystalline silicon device treated with perfluorodecyltrichlorosilane (PFTS). The wear surfaces of sidewall friction devices treated with selective tungsten are shown in Figure 8.6. A small wear scar is produced on the contact surface of the post, with no evident wear mark on the moving beam. This is common in sliding tests, where the wear is more severe on the body that is stationary with respect to the contact zone than the one that is moving with respect to the contact. In comparison, the surfaces of devices coated with alkylsilane coupling agents exhibit copious debris formation in environments containing oxygen and water vapor [8.6]. Fig. 8.6 Contact surfaces of selective tungsten coated sidewall tribometer after running in air at 20% RH for 300,000 cycles. Image (a) shows the view of the post as seen from behind the moving beam, (b) shows the wear spot on the post, and (c) shows the corresponding contact location on the beam. 79 10 5 10 6 3 µm 750 nm 750 nm (a) (b) (c)
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SANDIA REPORT SAND2004-1319 Unlimit
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SAND2004-1319 Unlimited Release Pri
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Contents ACKNOWLEDGEMENTS..........
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6.5 Summary........................
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List of Figures Figure 1.1 SEM micr
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Figure 6.2 Contact between an elast
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Preface Our team was involved in a
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strength. The subsequent chapter di
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Fig. 1.3. SEM image of cylindrical
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Fig. 1.5. Schematic of primary feat
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Fig 1.7 Double-hinged pull-tab tens
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Fig 1.10. SEM image of optical forc
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2 Strength Distributions in SUMMiT
Page 27 and 28: 2.2 Critical Flaw Size Evaluation T
Page 29 and 30: Fig. 2.5. SEM micrograph of pull-ta
Page 31 and 32: (1) Differences in surface roughnes
Page 33 and 34: 3 The Role Of Microstructure In SUM
Page 35 and 36: crystallographic orientation of a g
Page 37 and 38: direction. Also, maximum stress loc
Page 39 and 40: 3.4 References 3.1 Randle, V., Micr
Page 41 and 42: has the advantage of distributing t
Page 43 and 44: and servovalve at a strain rate of
Page 45 and 46: 4.6 References 4.1. TJ Garino, AM M
Page 47 and 48: microscopy studies. As a first step
Page 49 and 50: Fig. 5.2. Orientation imaging of a
Page 51 and 52: Fig. 5.5. Orientation imaging of a
Page 53 and 54: 6 Novel Techniques for Measurement
Page 55 and 56: of adhesion, and, (iv) a smaller co
Page 57 and 58: Force (mN) Fig. 6.5. Typical load-d
Page 59 and 60: 7 Impact of Silane Degradation Due
Page 61 and 62: All samples were coated with alkyls
Page 63 and 64: the friction structure and the cali
Page 65 and 66: 7.4 RESULTS 7.4.1 Simulation of dos
Page 67 and 68: Dose (MeV/g) Fig. 7.4. Results of X
Page 69 and 70: heating on contact angle for PFTS.
Page 71 and 72: the C-C backbone of the PFTS molecu
Page 73 and 74: The increase in static friction for
Page 75 and 76: 8 Friction and Wear of Selective Tu
Page 77: During processing of microelectrome
Page 81 and 82: 9 Conclusions and Recommendations T
Page 83: 10 Distribution 3 MS 0889 M.T. Dugg
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