Fabrication of wafer-level thermocompression bonds

Tsau, Christine H.; Spearing, S. Mark; Schmidt, M.A.

doi:10.1109/jmems.2002.805214

Cited by 80 publications

(40 citation statements)

References 22 publications

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“…The details of the fabrication process have been reported in [7], so only a brief outline is given here. Each wafer pair consisted of two 4 Si wafers, one of which is a double side by 6 mm and spaced 250 apart, were formed after lift-off.…”

Section: Methodsmentioning

confidence: 99%

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Characterization of Wafer-Level Thermocompression Bonds

Tsau

Spearing

Schmidt

2004

J. Microelectromech. Syst.

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Abstract-Thermocompression bonding joins substrates via a bonding layer. In this paper, silicon substrates were bonded using gold thin films. Experimental data on the effects of bonding pressure (30 to 120 MPa), temperature (260 and 300 C), and time (2 to 90 min) on the bond toughness, measured using the four-point bend technique, are presented. In general, higher temperature and pressure lead to higher toughness bonds. Considerable variation in toughness was observed across specimens. Possible causes of the nonuniform bond quality were explored using finite element analysis. Simulation results showed that the mask layout contributed to the pressure nonuniformity applied across the wafer. Finally, some process guidelines for successful wafer-level bonding using gold thin films are presented.[1170]

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Section: Methodsmentioning

confidence: 99%

“…Among the host of variables, the parameters that brings surfaces into close proximity for bonding to occur are believed to have the most impact on the bond quality. The effect of bonding layer thickness was explored previously [7]. This paper discusses the effects of bond pressure, temperature, and time on the measured bond toughness.…”

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confidence: 99%

Characterization of Wafer-Level Thermocompression Bonds

Tsau

Spearing

Schmidt

2004

J. Microelectromech. Syst.

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“…Then a bonding pressure of 0.1 MPa is applied across the two substrates for 15 min (corresponding to 5 MPa of pressure on the gold anchor pads). Afterwards, the temperature is ramped down slowly (Tsau et al, 2002). To machine the silicon substrate into a cantilever shape, we use deep reactive ion etch (DRIE) from the backside of the silicon wafer.…”

Section: Designmentioning

confidence: 99%

Remotely adjustable check-valves with an electrochemical release mechanism for implantable biomedical microsystems

Pan

Baldi

Ziaie

2007

Biomed Microdevices

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In this paper, we present two remotely adjustable check-valves with an electrochemical release mechanism for implantable biomedical microsystems. These valves allow one to vary the opening pressure set-point and flow resistance over a period of time. The first design consists of a micromachined check-valve array using a SU-8 polymer structural layer deposited on the top of a gold sacrificial layer. The second design is based on a variable length cantilever beam structure with a gold sacrificial layer. The adjustable cantilever-beam structure is fabricated by gold thermo-compression bond of a thin silicon wafer over a glass substrate. In both designs, the evaporated gold can be electrochemically dissolved using a constant DC current via a telemetry link. In the first design the dissolution simply opens up individual outlets, while in the second design, gold anchors are sequentially dissolved hence increasing the effective length of the cantilever beam (reducing the opening pressure). A current density of 35 mA/cm 2 is used to dissolve the gold sacrificial layers. Both gravity and syringe-pump driven flow are used to characterize the valve performance. A multi-stage fluidic performance (e.g. flow resistance and opening pressure) is clearly demonstrated.

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“…At 300 • C, a 1500 N force is applied to the wafers and held for 5 min which is typical for thermocompression bonding [79] [80]. The next stage is heating to 400…”

Section: Eutectic Bondingmentioning

confidence: 99%

Sample extraction and injection with a microscale preconcentrator.

Robinson

Chan²

2007

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This report details the development of a microfabricated preconcentrator that functions as a fully integrated chemical extractor-injector for a microscale gas chromatograph (GC). The device enables parts-per-billion detection and quantitative analysis of volatile organic compounds (VOCs) in indoor air with size and power advantages over macro-scale systems. The 44 mm 3 preconcentrator extracts VOCs using highly adsorptive, granular forms of graphitized carbon black and carbon molecular sieves. The micron-sized silicon cavities have integrated heating and temperature sensing allowing low power, yet rapid heating to thermally desorb the collected VOCs (GC injection). The keys to device construction are a new adsorbent-solvent filling technique and solvent-tolerant wafer-level silicon-gold eutectic bonding technology. The product is the first granular adsorbent preconcentrator integrated at the wafer level. Other advantages include exhaustive VOC extraction and injection peak widths an order of magnitude narrower than predecessor prototypes. A mass transfer model, the first for any microscale preconcentrator, is developed to describe both adsorption and desorption behaviors. The physically intuitive model uses implicit and explicit finite differences to numerically solve the required partial differential equations. The model is applied to the adsorption and desorption of decane at various concentrations to extract Langmuir adsorption isotherm parameters from effluent curve measurements where properties are unknown a priori.

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Fabrication of wafer-level thermocompression bonds

Cited by 80 publications

References 22 publications

Characterization of Wafer-Level Thermocompression Bonds

Characterization of Wafer-Level Thermocompression Bonds

Remotely adjustable check-valves with an electrochemical release mechanism for implantable biomedical microsystems

Sample extraction and injection with a microscale preconcentrator.

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