Electrical and chemical characterizations of hafnium (IV) oxide films for biological lab-on-a-chip devices

Many biological lab-on-a-chip applications require electrical and optical manipulation as well as detection of cells and biomolecules. This provides an intriguing challenge to design robust microdevices that resist adverse electrochemical side reactions yet achieve optical transparency. Physical isolation of biological samples from microelectrodes can prevent contamination, electrode fouling, and electrochemical byproducts; thus this manuscript explores hafnium oxide (HfO2) films – originating from traditional transistor applications – for suitability in electrokinetic microfluidic devices for biological applications. HfO2 films with deposition times of 6.5, 13, and 20 min were sputter deposited onto silicon and glass substrates. The structural, optical, and electrical properties of the HfO2 films were investigated using atomic force microscopy (AFM), X-ray diffractionenergy dispersive X-ray spectroscopyFourier transform infrared spectroscopy, ellipsometry, and capacitance voltage. Electric potential simulations of the HfO2 films and a biocompatibility study provided additional insights. Film grain size after corrosive Piranha treatment was observed via AFM. The crystalline structure investigated via X-ray diffraction revealed all films exhibited the (111) characteristic peak with thicker films exhibiting multiple peaks indicative of anisotropic structures. Energy dispersive X-ray spectroscopy via field emission scanning electron microscopy and Fourier transform infrared spectroscopy both corroborated the atomic ratio of the films as HfO2. Ellipsometry data from Si yielded thicknesses of 58, 127, and 239 nm and confirmed refractive index and extinction coefficients within the normal range for HfO2; glass data yielded unreliable thickness verifications due to film and substrate transparency. Capacitance-voltage results produced an average dielectric constant of 20.32, and the simulations showed that HfO2 dielectric characteristics were sufficient to electrically passivate planar microelectrodes. HfO2 biocompatibility was determined with human red blood cells by quantifying the hemolytic potential of the HfO2 films. Overall results support hafnium oxide as a viable passivation material for biological lab-on-a-chip applications.

Collins, J.L., Hernandez, H.M., Habibi, S., Kendrick, C.E., Wang, Z., Bihari, N., Bergstrom, P.L. and Minerick, A.R., 2018. Electrical and chemical characterizations of hafnium (IV) oxide films for biological lab-on-a-chip devices. Thin Solid Films662, pp.60-69.


3D Optical Profiler

The new 3D profiler (https://www.filmetrics.com/opticalprofilers/profilm3d) has arrived and is installed. The system will allow for measuring the surface profile of samples to extract feature heights and surface roughness. Contact Dr. Kendrick (cekendri@mtu.edu) if you would like to learn more about the system.

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Per spec

object spec

Mech spec

 

 


MFF and SYP

The Microfabrication Core Facility (MFF) was host to 15 students from the Summer Youth Program (SYP) on the 18th of July (and a further more on the 25th of July), aged from 12 – 14 years. The students learned about the fabrication of silicon based devices and how silicon wafers are produced. Additionally, they had hands on experience in the cleanroom and used the photolithography process to transfer a pattern on a photomask to a silicon wafer. The pattern had a scale on it from 100 um (diameter of a human hair) to 1 um (diameter of bacteria) to allow the students to understand the scale that MFF users work at. The students also hand cleaved silicon wafers to produce dies of gold Michigan Technological University (MTU) logos as a keepsake for their time in the MFF.

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The last group of five students gowned up and ready to do the photolithography process.

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Left – The wafers after the photolithography process, Right – Gold MTU logos ready to cleave

If you are interested in what the MFF can do regarding teaching/research/K-12 contact Dr. Chito Kendrick, cekendri@mtu.edu or microfabrication@mtu.edu.

 


Portable Blood-Typing

Portable Blood-Typing research in a lab

Adrienne Minerick, a professor of chemical engineering and associate dean of
the College of Engineering at Michigan Tech, has spun off Microdevice Engineering, Inc.
to market her portable blood-typing technology. Together with Mary Raber,
assistant dean of academic programs in Michigan Tech’s Pavlis Honors College,
Minerick is developing a handheld point-of-care device to type ABO-Rh blood and
hematocrit (blood cell concentration) in five minutes. The device is being engineered
to be as easy to use as a blood glucose meter.

The lab on a chip devices being used by Adrienne Minerick’s cop many are being
fabricated using the Microfabrication Core Facility.



MFF Equipment Status

Instrument Status Status Notes
6″ Sputter deposition  Ready Online

Issues – Water flow meter is not indicating flow

20180102 – Replaced the outlet water connectors as one had cracked and leaked water on the floor

20180406 – Replaced the pump oil and cleaned both the top and bottom seals on the chamber

8″ Sputter deposition Ready Online

Issues – Need to fix the hoist or take weight off the system

Denton e-beam deposition  Ready Online

Issues – None

20180102 – Cryo Regenerated

Fredrick e-beam deposition  Ready Online

Issues – Needs to be bead blasted, install mirror to see the beam, and check the pump for a leak

20171024 – Water lines replaced after one cracked, New Al crucible

Parylene Coater  Ready Ready

Issues – Needs to be added to e-logger

TRION  Ready Online

Issues – Reduced O2 flow for clean recipe as the throttle valve and can not control the flow, need to replace the rough pump

20171127 – Replaced the oil after the pump run out, leak in a seal still

20180622 – Replaced the lid o-ring (#383) there was a leak rate of 1Torr/min

CAIBE  Ready Online

20180420 – Installed new stage, fixed the water line that melted, removed the load lock turbo from the cooling as it was blocked and not needed

20180601 – Installed a new microwave source

March  Useable Online

Issues – Cross talk between the tuner and MFC boxes, need to try and have an external PSU, the RF supply randomly turns off

20180127 – Connected water lines to the RF base

Ellipsometer  Ready Ready

Issues – None

20171024 – Light source realigned to give a lower gain of 2

FTIR  Ready Ready

Issues – Calibration

Curvature System  Ready Ready

Issues – Calibration

Oxidation Furnace  Ready Ready

Issues – Need to determine if the wet oxidation is working correctly

Fall 2017 – Installed a water bubbler, but the lines are not sending the steam to the furnace correctly.

20180131 – Installed a new TC for zone 2, testing in the lab class

20180604 – Installed a new controller and the system seems stable

Diffusion Furnace  Ready Ready

Issues – None

2″ Furnace  Ready Ready

Issues – None

RTP  Useable Chiller is leaking water if run at too higher pressure

Issues – Need to make sure we have the proper cooling

Dicing Saw  Ready Ready

Fall 2017 – Moved the water supply off the tape to the building supply, replaced a leaking water pressure switch

20180413 – Replaced the pressure flow switch but it is not fast enough or not sending the right signal that there is water in time.

20180601 – Replaced several of the boards after boards 6 and 7 were swapped as recommended by the company and this lead to several issues with burnt out leads and blown fuses

20180814 – Installed a 12VDC power supply that will need to be manually turned on to turn on the water, fix for the water pressure issues. The optics head was realigned as it became lose and users had been bumping it.

20180901 – Installed a Cole-Parmer Venturi Vacuum Pump, 3.2 cfm, 28.0″Hg

EVG 620 Mask Aligner  Ready Ready – Turning off the lamp to preserve the life time

Issues – Logging sometimes fails as the optics stage gets stuck

20180814 – Fixed three air leaks, two on the right side of the stage as the tubes had cracked

Wet bench – Chemical processing  Ready Ready

Issues – Air leaks

Vacuum oven  Ready Ready

Issues – None

20180131 – Installed a vacuum pump

Hotplates  Ready Ready

Issues – None

Spinner  Ready Ready

Issues – None

Wire bonder  Ready Ready

Issues – None

Cleanroom Optical Microscopy  Ready Ready

Issues – Calibrate the CCD capture measurements, can use the SYP mask

Probe station  Ready Ready

Issues – 20180913 x-y belt replaced with a No slip positive drive belt RBC PIC DESIGN PART#F32BS18-112

Parameter Analyzer  Ready Ready

Issues – See above

Capacitance Voltage Measurement  Ready Ready

Issues – Need to automate

Four point conductivity  Ready Ready

Issues – Need to automate

Atomic Layer Deposition Useable Need to install N2 on the precusor and check it is pulsing properly and then install TDMAH.

201805023 – set up the process to represent an ALD valve that has constant Ar carrier flow

20180601 – Installed Ferrocene iron ALD source

20180814 – changed the precursor setup – Ferrocene is not producing a vapor pressure?

Filmertics 3D Profiler Ready Ready for training and usage

20171127 – 100x received and installed

20180814 – Had to realign the fringes with the focus point.

Big blue wet benches Useable  20180814

1 – I put in a new controller for the right bench and it allows for the bench to be used. The old controller might be ok, but I did not realize you had to power cycle the bench with the main breaker if the EPO is pressed. There is still an alarm going and I am not sure yet what is causing it.
2 – I started checking the controls to see if everything works – did not get very far, but there is running DIW and N2
3 – The aspirators are not working and this is very much likely because Bill has decided to run these to the new acid waste storage tank instead of the current one. To finish the new tank will take significant time and funds to get operational and with the current usage I do not see the point. I might be able to tee into the current tank, however I am not sure what has been done to turn off the aspirators.
4 – The left bath seems to have no power, but the breaks are not labelled to know where the power is going – luckily for me there is only one break currently off – however it did not turn on the left controller for the bench.
5 – The left bench is not connected at all for waste and this will mean breaking the lines on the 3rd floor to install tees and then running tubes up to the 4th floor to be connected.

Northern Nano Lab Alliance Training Grant Program

The National Science Foundation’s National Nano Coordinated Infrastructure Program (http://www.nnci.net/) has set up a network of nodes to support nano-related research and education. Headquartered at the University of Minnesota, the Midwest Infrastructure Corridor (MINIC) is one of those nodes. MINIC has national reach, supporting work in Nano-bio, 2D materials, and other emerging fields. However MINIC also has a responsibility to support and enable other nano and micro fabrication laboratories in the upper Midwest. To accomplish this latter goal MINIC has created the Northern Nano Lab Alliance (NNLA)(http://www.minic.umn.edu/nano-lab-alliance). Currently made up of eight labs, this organization meets regularly to share best practices, and develop new methods to improve lab operation.

MINIC is pleased to announce a new Training Grant Program to members of the Northern Nano Lab Alliance. This program is intended to train researchers and provide low-cost access to tools that are not available at their home labs. This may be used to enable various research projects or to provide participants with desirable skills. The basic rules are laid out as follows:

MINIC will provide program participants tool access at 50% of the current academic rate (http://www.nfc.umn.edu/assets/pdf/access_rates_academic.pdf). This subsidy is limited to $1500 per year per participant. Participants are encouraged to carry out the processing work during a visit to maximize the training experience. Where this is impractical, remote training will be available on a limited set of tools. Contact the NNLA coordinator (cibuzar@umn.edu) for a current list.


Ultra-thin transparent conducting oxides

AFM ImagesLimitations of ultra-thin transparent conducting oxides for integration into plasmonic-enhanced thin-film solar photovoltaic devices

Gwamuri, J., Vora, A., Khanal, R.R. et al. Mater Renew Sustain Energy (2015) 4: 12. doi:10.1007/s40243-015-0055-8

This study investigates ultra-thin transparent conducting oxides (TCO) of indium tin oxide (ITO), aluminum-doped zinc oxide (AZO) and zinc oxide (ZnO) to determine their viability as candidate materials for use in plasmonic-enhanced thin-film amorphous silicon solar photovoltaic (PV) devices.

Read more at Materials for Renewable and Sustainable Energy.


Welcome

M and M BuildingWelcome to the new microfabrication core facility website, it has been a long time coming and hopefully it will help answer most questions you have about the microfabrication core facilities capabilities, access, and policies. This website would have not been possible with out the hard work by Sue Hill.

If you would like a link posted to your personnel website or research group please let me know and I can have you added to the Networking section. This is not only to highlight our users, but to also allow for past, present, and future users to find collaborators at Michigan Technological University.