Bond Pad Effects on Steady State Thermal Conductivity Measurement Using Suspended Micromachined Test Structures

Phinney, Leslie M.; Piekos, Edward S.; Kuppers, Jaron

doi:10.1115/imece2007-41349

Cited by 5 publications

(8 citation statements)

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“…The thermal test structures were previously used for thermal-conductivity measurements Phinney et al, 2007) and fabricated as part of reticle set 539 (RS539) module 5 (Mod5). The suspended-bridge thermal test structures were fabricated from the Poly4 layer and are nominally 2.25 µm thick.…”

Section: Mems Test Structures For Model Validationmentioning

confidence: 99%

“…For the thermal conductivity of polysilicon, previously presented experimental values for nominally the same structure were used in conjunction with a phenomenological argument to provide an analytical function that allows the measurements to be extended to higher temperatures and to be corrected for run-to-run variations as well as biases in the measurements, as detailed in Phinney et al (2007).…”

Section: Thermophysical Properties Of Summit V Materialsmentioning

confidence: 99%

“…These values agree to a reasonable accuracy for temperatures higher than approximately 200 K, where sample-size effects are unimportant for millimeter-scale samples. Measurements are also available for a number of polysilicon materials (e.g., Paul et al, 1994;von Arx et al, 2000;McConnell et al, 2001;Graham et al, 2003;Phinney et al, 2007), but these values differ greatly, not only in their magnitude, but in the nature of their variation with temperature. The measurements from a large number of investigators are shown in Comparison of published polysilicon thermal-conductivity measurements.…”

Section: Thermophysical Properties Of Summit V Materialsmentioning

confidence: 99%

“…While high-temperature measurements exist for the thermal conductivity of Poly4, it was measured only on 10×200 µm bridges, so the biases described in Phinney et al (2007) cannot be estimated. Comparing these values with that of 10×200 µm and 10×500 µm bridges in Figure 4.4 demonstrates the issue.…”

Section: Thermophysical Properties Of Summit V Materialsmentioning

confidence: 99%

“…The offset between the RS539 data sets is an artifact of the measurement because the materials comprising the short and long bridges are largely identical. Because some of the biases identified in Phinney et al (2007) are setup-dependent, it is possible that the difference between the RS485 and RS539 10×200 µm bridges is also an artifact although material differences are also possible because they were produced in separate runs. Comparison of assumed P4 thermal conductivity to published data and fits.…”

Section: Thermophysical Properties Of Summit V Materialsmentioning

confidence: 99%

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Validation of thermal models for a prototypical MEMS thermal actuator.

Gallis¹,

Torczynski²,

Piekos³

et al. 2008

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This report documents technical work performed to complete the ASC Level 2 Milestone 2841: validation of thermal models for a prototypical MEMS thermal actuator. This effort requires completion of the following task: the comparison between calculated and measured temperature profiles of a heated stationary microbeam in air. Such heated microbeams are prototypical structures in virtually all electrically driven microscale thermal actuators. This task is divided into four major subtasks. (1) Perform validation experiments on prototypical heated stationary microbeams in which material properties such as thermal conductivity and electrical resistivity are measured if not known and temperature profiles along the beams are measured as a function of electrical power and gas pressure. (2) Develop a noncontinuum gas-phase heat-transfer model for typical MEMS situations including effects such as temperature discontinuities at gas-solid interfaces across which heat is flowing, and incorporate this model into the ASC FEM heat-conduction code Calore to enable it to simulate these effects with good accuracy. (3) Develop a noncontinuum solid-phase heat transfer model for typical MEMS situations including an effective thermal conductivity that depends on device geometry and grain size, and incorporate this model into the FEM heat-conduction code Calore to enable it to simulate these effects with good accuracy. (4) Perform combined gas-solid heat-transfer simulations using Calore with these models for the experimentally investigated devices, and compare simulation and experimental temperature profiles to assess model accuracy. These subtasks have been completed successfully, thereby completing the milestone task. Model and experimental temperature profiles are found to be in reasonable agreement for all cases examined. Modest systematic differences appear to be related to uncertainties in the geometric dimensions of the test structures and in the thermal conductivity of the polycrystalline silicon test structures, as well as uncontrolled nonuniform changes in this quantity over time and during operation. 4 ACKNOWLEDGMENTSThe authors gratefully acknowledge the careful technical reviews of this report by Michael J. Shaw and Sean P. Kearney and the thorough programmatic reviews of this project by

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Section: Mems Test Structures For Model Validationmentioning

confidence: 99%

Section: Thermophysical Properties Of Summit V Materialsmentioning

confidence: 99%

Section: Thermophysical Properties Of Summit V Materialsmentioning

confidence: 99%

Section: Thermophysical Properties Of Summit V Materialsmentioning

confidence: 99%

Section: Thermophysical Properties Of Summit V Materialsmentioning

confidence: 99%

See 3 more Smart Citations

Validation of thermal models for a prototypical MEMS thermal actuator.

Gallis¹,

Torczynski²,

Piekos³

et al. 2008

View full text Add to dashboard Cite

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Modified data analysis for thermal conductivity measurements of polycrystalline silicon microbridges using a steady state Joule heating technique

Sayer

Piekos

Phinney

2012

Review of Scientific Instruments

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Accurate knowledge of thermophysical properties is needed to predict and optimize the thermal performance of microsystems. Thermal conductivity is experimentally determined by measuring quantities such as voltage or temperature and then inferring a thermal conductivity from a thermal model. Thermal models used for data analysis contain inherent assumptions, and the resultant thermal conductivity value is sensitive to how well the actual experimental conditions match the model assumptions. In this paper, a modified data analysis procedure for the steady state Joule heating technique is presented that accounts for bond pad effects including thermal resistance, electrical resistance, and Joule heating. This new data analysis method is used to determine the thermal conductivity of polycrystalline silicon (polysilicon) microbridges fabricated using the Sandia National Laboratories SUMMiT V™ micromachining process over the temperature range of 77-350 K, with the value at 300 K being 71.7 ± 1.5 W/(m K). It is shown that making measurements on beams of multiple lengths is useful, if not essential, for inferring the correct thermal conductivity from steady state Joule heating measurements.

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Thermal Conductivity Measurements on Polycrystalline Silicon Microbridges Using the 3ω Technique

Hopkins

Phinney

2009

Journal of Heat Transfer

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The thermal performance of microelectromechanical systems devices is governed by the structure and composition of the constituent materials as well as the geometrical design. With the continued reduction in the characteristic sizes of these devices, experimental determination of the thermal properties becomes more difficult. In this study, the thermal conductivity of polycrystalline silicon (polysilicon) microbridges are measured with the transient 3 technique and compared with measurements on the same structures using a steady state Joule heating technique. The microbridges with lengths from 200 m to 500 m were designed and fabricated using the Sandia National Laboratories SUMMiT V™ surface micromachining process. The advantages and disadvantages of the two experimental methods are examined for suspended microbridge geometries. The differences between the two measurements, which arise from the geometry of the test structures and electrical contacts, are explained by bond pad heating and thermal resistance effects.

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Bond Pad Effects on Steady State Thermal Conductivity Measurement Using Suspended Micromachined Test Structures

Cited by 5 publications

References 0 publications

Validation of thermal models for a prototypical MEMS thermal actuator.

Validation of thermal models for a prototypical MEMS thermal actuator.

Modified data analysis for thermal conductivity measurements of polycrystalline silicon microbridges using a steady state Joule heating technique

Thermal Conductivity Measurements on Polycrystalline Silicon Microbridges Using the 3ω Technique

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