Microelectromechanical Systems

Zangari, Giovanni

doi:10.1002/9780470602638.ch28

Cited by 10 publications

(14 citation statements)

References 101 publications

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“…Electrodeposition of gold is the metallization process of choice for interconnects, and electrical contacts in compound semiconductors, as well as optoelectronic and biomedical applications as described in recent reviews. [1][2][3] In addition to useful electrical properties gold also shows excellent plasmonic properties at room temperature, but is susceptible to deformations caused by high energy densities encountered in plasmonic devices. 4 Traditional cyanide-based gold plating solutions are becoming increasingly unpopular for obvious toxicity concerns including possible liberation of toxic HCN gas in the reaction with acids, worksite safety, effluent treatment etc.…”

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confidence: 99%

Mechanism and Stability Study of Gold Electrodeposition from Thiosulfate-Sulfite Solution

Estrine¹,

Riemer²,

Venkatasamy³

et al. 2014

J. Electrochem. Soc.

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Electrodeposition of gold from a basic "fresh" and "used" thiosulfate-sulfite solution containing 0.02 M Na 3 Au(S 2 O 3 ) 2 has been investigated on Au and Pt electrodes using various electroanalytical techniques (CV, LSV, RDE), controlled potential electrodeposition, as well as constant current and pulse current deposition. It was proposed that irreversible one electron reduction to gold-run in "fresh" solution-at the Pt electrode starts from Au(S 2 O 3 )(SO 3 ) 2 5− , a mixed gold thiosulfate -sulfite complex with a high stability constant (log β = 30.8). A diffusion coefficient of 1.77 × 10 −6 cm 2 /s for Au (S 2 O 3 ) (SO 3 ) 2 5− was calculated from the slope of the linear plot i p -ν 1/2 obtained with a Pt electrode, which is lower than the value of diffusion coefficient (D = 4.6 × 10 −6 cm 2 /s) obtained for the Au (S 2 O 3 ) 2 3− complex (log β = 26.0) present in the "used" solution. The voltammograms for gold deposition on the Au electrode were significantly different from those on Pt indicating that the electron transfer was influenced by the coupled chemical reaction. The natures of possible chemical reactions are discussed.Electrodeposition of gold is the metallization process of choice for interconnects, and electrical contacts in compound semiconductors, as well as optoelectronic and biomedical applications as described in recent reviews. 1-3 In addition to useful electrical properties gold also shows excellent plasmonic properties at room temperature, but is susceptible to deformations caused by high energy densities encountered in plasmonic devices. 4 Traditional cyanide-based gold plating solutions are becoming increasingly unpopular for obvious toxicity concerns including possible liberation of toxic HCN gas in the reaction with acids, worksite safety, effluent treatment etc. Excess of cyanide ions, liberated during electrochemical reduction of the Au(CN) 2 − complex, can attack photoresist, resulting in lift-off of the resist and deposition of extraneous gold underneath the interface between resist and substrate. 3,5-7 In order to address these shortcomings, new non-cyanide solutions including sulfite, thiosulfate, mixed sulfite-thiosulfate, and organic additives as a solution-stabilizers have been evaluated. 1-3 Compared to cyanide, these non-cyanide electrolytes are environmentally friendly, but suffer from SO 2 , and colloidal sulfur formation in neutral and acidic media. 5-7 The instability of sulfite and thiosulfate electrolytes can be improved through addition of organic and inorganic bath stabilizers. 6-8 Thiosulfate plating solutions are unstable under neutral and acidic conditions due to thiosulfate decomposition and formation of "colloidal" sulfur. 2"Colloidal" sulfur is also formed by the protonation of excess S 2 O 3 2− ions according to the following equation:The precipitation of "colloidal" sulfur which occurs with precipitation of all gold thiosulfate complexes is catastrophic when it happens in an industrial electrodeposition tool. The addition of sulfite into the thiosulfate s...

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confidence: 99%

Mechanism and Stability Study of Gold Electrodeposition from Thiosulfate-Sulfite Solution

Estrine¹,

Riemer²,

Venkatasamy³

et al. 2014

J. Electrochem. Soc.

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“…3c). Subsequently, defined by photoresist (AZ4620) patterns (5 µm in thickness), strips of Permalloy (220 × 35 × 3 µm) were electroplated using an established recipe [41] (Fig. 3d).…”

Section: Methodsmentioning

confidence: 99%

“…An additional Parylene layer (1 μm in thickness) was then deposited to seal the sacrificial photoresist, followed by thermally deposited Cr/Au (5 100 nm −1 ) to form moving electrodes and permalloy seed layer (figure 3(c)). Subsequently, defined by photoresist (AZ4620) patterns (5 μm in thickness), strips of Permalloy (220 × 35 × 3 μm) were electroplated using an established recipe [41] (figure 3(d)). This was followed by removal of the photoresist with photoresist stripper (AZ 400T, AZ Electronic Materials), patterning of the moving electrodes (500 × 500 μm) and deposition of a final Parylene passivating layer (3 μm)…”

Section: Fabrication Processmentioning

confidence: 99%

A MEMS differential viscometric sensor for affinity glucose detection in continuous glucose monitoring

Huang¹,

Li²,

Davis³

et al. 2013

J. Micromech. Microeng.

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Micromachined viscometric affinity glucose sensors have been previously demonstrated using vibrational cantilever and diaphragm. These devices featured a single glucose detection module that determines glucose concentrations through viscosity changes of glucose-sensitive polymer solutions. However, fluctuations in temperature and other environmental parameters might potentially affect the stability and reliability of these devices, creating complexity in their applications in subcutaneously implanted continuous glucose monitoring (CGM). To address these issues, we present a MEMS differential sensor that can effectively reject environmental disturbances while allowing accurate glucose detection. The sensor consists of two magnetically driven vibrating diaphragms situated inside microchambers filled with a boronic-acid based glucose-sensing solution and a reference solution insensitive to glucose. Glucose concentrations can be accurately determined by characteristics of the diaphragm vibration through differential capacitive detection. Our in-vitro and preliminary in-vivo experimental data demonstrate the potential of this sensor for highly stable subcutaneous CGM applications.

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“…Electrochemical deposition applications in magnetic MEMS: Zangari provides an overview over electrodeposited metals used in MEMS [161], listing Au, Cu, Ni, and Ni alloy. Ni alloys include NiFe, NiCo, NiW, NiMo, NiP, and NiMn.…”

Section: Electrochemical Deposition System and Processmentioning

confidence: 99%

Deposition Technologies

Gatzen¹,

Saile²,

Leuthold³

2015

Micro and Nano Fabrication

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Deposition of thin-films used in MEMS and NEMS devices rely on a wide variety of technologies. Physical vapor deposition (PVD) uses physical effects like evaporation or ion bombardment to create thin-films on a substrate by forcing source atoms into a gaseous phase. Chemical vapor deposition (CVD) and similar processes create coatings by a chemical reaction of volatile species by using reaction processes defined by chemical reaction equations. While PVD and CVD are dry processes, for depositing conductive thin-films the substrate may be submerged in an electrically conductive liquid (an electrolyte) and subjected to electrochemical or chemical deposition. Spin-coating and spray-coating are two examples of technologies that lend themselves to creating organic films-a technology widely used in depositing photoresists in photolithography. Dip processes like solgel may be used for the creation of oxide coatings.

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Microelectromechanical Systems

Cited by 10 publications

References 101 publications

Mechanism and Stability Study of Gold Electrodeposition from Thiosulfate-Sulfite Solution

Mechanism and Stability Study of Gold Electrodeposition from Thiosulfate-Sulfite Solution

A MEMS differential viscometric sensor for affinity glucose detection in continuous glucose monitoring

Deposition Technologies

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