Multilayer etch masks for 3-dimensional fabrication of robust silicon carbide microstructures

Dowling, Karen M.; Suria, Ateeq J.; Shankar, Ashwin; Chapin, Caitlin A.; Senesky, Debbie G.

doi:10.1109/memsys.2015.7050944

Cited by 9 publications

(8 citation statements)

References 17 publications

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“…Silicon Carbide mesas [11], beams [7], disks [8] and high-aspect ratio gaps [12] have been demonstrated in 4H-SiC on Insulator (SiCOI) using oxide-oxide wafer bonding and DRIE etching using SF6/O2 and SF6/Ar chemistries. Doped SiCOI technology is ideal for defining and isolating resonators and electrostatic actuators.…”

Section: Device Fabricationmentioning

confidence: 99%

“…The slow etch rates ensures no footing effect at the base during the 190 um backside etch. After release Nickel and seed layer are stripped leaving behind pristine SiC resonators; (Right) SEMs of clamped-clamped beams (a) and cantilevers (b).The sidewalls are smooth no micro-masking because we reduced the etch-rate compared to[11]. Small diaphragms are left at the anchor after front-side release, potentially undermining the Q.…”

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confidence: 99%

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SiC Cantilevers for Generating Uniaxial Stress

Jiang

Opondo

Wolfowicz

et al. 2019

2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems &Amp; Eurosensors XXXIII (TRANSDUCERS &Am

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This paper demonstrates the first beam resonators fabricated from bulk high purity semi-insulating 4H Silicon Carbide wafers (HPSI 4H-SiC). Our innovations include:(1) Multi-level front-side, back-side inductively coupled plasma-deep reactive ion etching (ICP-DRIE) technology to fabricate thin, low-mass, bending-mode resonators framed by the SiC substrate (2) Laser Doppler Vibrometer (LDV) measurements of mechanical quality factors (Q) > 10,000 with frequencies ranging from 300 kHz to 8MHz and (3) Calculated uniaxial in-plane surface stress 20 MPa at top surface of resonator base when operating at resonance in vacuum.

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Section: Device Fabricationmentioning

confidence: 99%

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confidence: 99%

SiC Cantilevers for Generating Uniaxial Stress

Jiang

Opondo

Wolfowicz

et al. 2019

2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems &Amp; Eurosensors XXXIII (TRANSDUCERS &Am

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“…The SiC was then etched using the baseline recipe and 50 W RF bias power. Since narrow trench openings require a longer etch rate [17], these samples were etched for 2.5 hours and 4 hours to reach depths from 50 to 100 µm.…”

Section: Sic Microchannel Fabrication Processmentioning

confidence: 99%

Inductive Coupled Plasma Etching of High Aspect Ratio Silicon Carbide Microchannels for Localized Cooling

Dowling

Suria

Won

et al. 2015

Volume 3: Advanced Fabrication and Manufacturing; Emerging Technology Frontiers; Energy, Health and Water- Applications of Nano

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High aspect ratio microchannels using high thermal conductivity materials such as silicon carbide (SiC) have recently been explored to locally cool micro-scale power electronics that are prone to on-chip hot spot generation. Analytical and finite element modeling shows that SiC-based microchannels used for localized cooling should have high aspect ratio features (above 8:1) to obtain heat transfer coefficients (300 to 600 kW/m2·K) required to obtain gallium nitride (GaN) device channel temperatures below 100°C. This work presents experimental results of microfabricating high aspect ratio microchannels in a 4H-SiC substrate using inductively coupled plasma (ICP) etching. Depths of 90 μm and 80 μm were achieved with a 5:1 and 12:1 aspect ratio, respectively. This microfabrication process will enable the integration of microchannels (backside features) with high-power density devices such as GaN-on-SiC based electronics, as well as other SiC-based microfluidic applications.

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“…More recent work focusing on etching through smaller (<10 µm) mask openings also employ constant flow (non-cyclic) SF 6 /O 2 -based processes with either a Ni mask [15][16][17][18] or a SiO 2 mask [19]. Interestingly, the highest achieved SiC aspect ratios (25.5 for 2 µm openings) utilized a non-cyclic recipe, wherein a warmer coupon during etching facilitated a deeper and more vertical SiC etch; the published recipe yields flat bottoms with close to vertical sidewalls for 3-6 µm openings, yet it is limited to 'V' shaped bottoms (slanted sidewalls) for 2 µm openings [15].…”

Section: Introductionmentioning

confidence: 99%

Deep reactive ion etching of 4H-SiC via cyclic SF₆/O₂ segments

Luna

Tadjer

Anderson

et al. 2017

J. Micromech. Microeng.

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Cycles of inductively coupled SF6/O2 plasma with low (9%) and high (90%) oxygen content etch segments are used to produce up to 46.6 µm-deep trenches with 5.5 µm-wide openings in single-crystalline 4H-SiC substrates. The low oxygen content segment serves to etch deep in SiC whereas the high oxygen content segment serves to etch SiC at a slower rate, targeting carbon-rich residues on the surface as the combination of carbon-rich and fluorinated residues impact sidewall profile. The cycles work in concert to etch past 30 µm at an etch rate of ~0.26 µm min−1 near room temperature, while maintaining close to vertical sidewalls, high aspect ratio, and high mask selectivity. In addition, power ramps during the low oxygen content segment is used to produce a 1:1 ratio of mask opening to trench bottom width. The effect of process parameters such as cycle time and backside substrate cooling on etch depth and micromasking of the electroplated nickel etch mask are investigated.

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Multilayer etch masks for 3-dimensional fabrication of robust silicon carbide microstructures

Cited by 9 publications

References 17 publications

SiC Cantilevers for Generating Uniaxial Stress

SiC Cantilevers for Generating Uniaxial Stress

Inductive Coupled Plasma Etching of High Aspect Ratio Silicon Carbide Microchannels for Localized Cooling

Deep reactive ion etching of 4H-SiC via cyclic SF₆/O₂ segments

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Multilayer etch masks for 3-dimensional fabrication of robust silicon carbide microstructures

Cited by 9 publications

References 17 publications

SiC Cantilevers for Generating Uniaxial Stress

SiC Cantilevers for Generating Uniaxial Stress

Inductive Coupled Plasma Etching of High Aspect Ratio Silicon Carbide Microchannels for Localized Cooling

Deep reactive ion etching of 4H-SiC via cyclic SF6/O2 segments

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Deep reactive ion etching of 4H-SiC via cyclic SF₆/O₂ segments