Measurement of the mechanical properties of electroplated gold thin films using micromachined beam structures

Baek, Chang-Wook; Kim, Yong-Kweon; Ahn, Yonghan; Kim, Yong-Hyup

doi:10.1016/j.sna.2003.11.041

Cited by 130 publications

(85 citation statements)

References 23 publications

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“…A diffusion mechanism for void formation was suggested. The Young's modulus, residual stress, and stress gradient in electroplated films were measured using surface micromachined beam structures [92]. The Young's modulus was calculated to be from 35.2 to 43.9 GPa using a value of Poisson's ratio of 0.42 for gold.…”

Section: Physical Propertiesmentioning

confidence: 99%

Electrodeposition of Gold

Kohl¹

2010

Modern Electroplating

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While all that glitters may not be gold, it is the most beautiful of all the elements in their pure form. The name gold comes from the Old English Anglo-Saxon word for geolo meaning "yellow" while the symbol, Au, comes from the Latin word aurum, meaning "glowing dawn." Historically gold was one of the first metals known. Gold has been valuable throughout the ages chiefly because of its physical properties of softness, ductility, corrosion resistance, density, and scarcity. The first gold coin dates back to about 560 BC. Gold cups and jewelry predating 3500 BC have been found in Iraq. The ancient Egyptians knew how to hammer gold into leaf as thin as 66 nm. The importance of gold as a form of currency was at a high point in the 1900s when most countries were on the gold standard. The bullion price of gold over the past 21 years is shown in Figure 4.1.There have been about 160 metric kilotons of gold mined since it was first discovered, and it occupies about 0.005 ppm of the earth's crust. The world demand for gold in 2007 was approximately 80,000,000 troy ounces. Figure 4.2 shows the breakdown of the gold usage by industry. Jewelry comprises the largest fraction of the usage; however, much of that is not electroplated. For jewelry applications, gold is commonly alloyed with group IB or IIB metals, particularly copper, silver, platinum, and palladium, principally to improve its strength and wear resistance.The electrodeposition of gold is a relatively new process; it has been traced to the early work of Brugnatelli in 1805 [1]. The motives behind the use of electroplated gold changed dramatically in the mid-twentieth century when the emerging electronics industry required special-purpose electrical connections. The electronics industry consumed 5,330,000 troy ounces in 1994. Figure 4.3 shows the growth in the use of gold in the electronics industry by year. The use of electroplated gold in a variety of different functions in the electronics industry has led to (1) many advances in our fundamental understanding of the electrodeposition process and (2) new electroplating technologies over the past 25 years.Electrochemically deposited gold has satisfied many of the demands of the electronics industry. Gold has the third best electrical and thermal conductivity of all metals at room temperature. Also it has high ductility and excellent wear resistance, which are important for electrical contacts. The inertness of gold prevents the formation of insulating surface oxides (as compared to metals like aluminum). Group IIB metals (e.g., gold) are not good catalysts for other reactions, thus avoiding certain problems. For example, group IB metals (particularly platinum and palladium) can catalyze the polymerization of organic molecules forming insulating layers. In addition, gold is an excellent metal for wire bonding integrated circuits (ICs). Gold wires can be bonded to pure, soft gold pads by thermocompression bonding (300-400 C at high pressure to form a weld) or thermosonic bonding (150-200 C with ultrasonic energy to fo...

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Section: Physical Propertiesmentioning

confidence: 99%

Electrodeposition of Gold

Kohl¹

2010

Modern Electroplating

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“…The Young's modulus of the electroplated gold sample is also significantly smaller than the 78 GPa reported for bulk gold (Davis 1998). A lack of data exists for the mechanical properties of electroplated thick gold layers, but this value is in the range reported for thin gold films 35-78 GPa (Baek et al 2005), which also has a fairly wide range, but shows a general trend of values below that of bulk gold.…”

Section: Test Resultsmentioning

confidence: 80%

VM-TEST: Mechanical property measurement using electrostatically actuated vertical MEMS test structures fabricated in thick metal layers

et al. 2011

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An efficient method is presented to determine the mechanical properties of thick metal layers using the pull-in voltage of electrostatically actuated structures. To fabricate these high aspect ratio beams without severe deformations, additional features were added, which made existing pull-in voltage equations inaccurate and therefore corrections were necessary. ANSYS Multiphysics was used to analyze the differences between ideal beams and the fabricated beams. To demonstrate the proposed approach, both nickel and gold devices were fabricated. To extract the material property values, a sum of least squares fitting scheme was used. A Young's modulus of 186.2 and 60.8 GPa was obtained for nickel and gold structures respectively. Both values are significantly smaller than values reported for bulk material, but fall within the range of values reported in the literature.

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“…Four distinct gold materials, studied by as many different authors are used for providing comparisons: Baek et al [8], Espinosa et al [9], Lee et al [10] and Kim et al [11]. The table 2 summarizes these materials characteristics.…”

Section: Literature Materials Comparisonmentioning

confidence: 99%

Inﬂuence of microstructure and internal stress on the mechanical behavior of electroplated gold freestanding thin ﬁlms

Martegoutte

Seguineau²,

Fourcade

et al. 2010

EPJ Web of Conferences

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Abstract. Mechanical properties of freestanding electroplated gold thin films were studied in relationship to their geometrical and microstructural properties. Three different techniques of characterization were used: nanoindentation, bulge tests and microtensile tests. Results were compared to literature and also discussed according to physical phenomena related to the elaboration process of the specimens like seed layer exodiffusion or internal stress state. The observed plasticity and failure mechanisms were found to be in good agreement with the literature and are consistent with the microstructure. The measured Young's modulus is slightly higher than expected, and SIMS analysis is exploited to explain such a high value.

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Measurement of the mechanical properties of electroplated gold thin films using micromachined beam structures

Cited by 130 publications

References 23 publications

Electrodeposition of Gold

Electrodeposition of Gold

VM-TEST: Mechanical property measurement using electrostatically actuated vertical MEMS test structures fabricated in thick metal layers

Inﬂuence of microstructure and internal stress on the mechanical behavior of electroplated gold freestanding thin ﬁlms

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