EE Ph.D. Oral Examination: Hyunjoo Jenny Lee, March 7, at 2:00 pm, Nano 232

Stanford University Ph.D. Oral Examination – Department of Electrical Engineering

 

Title: Capacitive Micromachined Ultrasonic Transducer (CMUT) Chemical Sensor And Its Interface Circuits

Speaker:  Hyunjoo Jenny Lee

Advisor:  Professor Pierre Khuri-Yakub

Date:  March 7, 2012 (Wednesday)

Time:  2:00 pm (refreshments at 1:45 pm)

Location: Nanoscale Science and Engineering (Nano) - Room 232

 

Abstract:

 

Miniaturized chemical sensors based on microelectromechanical-systems (MEMS) offer competitive advantages over the existing bench-top chemical analyzers, such as small size, low power consumption, low cost due to batch fabrication, and CMOS compatibility. The potential for system integration of these chemical sensors with on-chip CMOS circuitry expands the spectrum of use, including consumer, industrial, and homeland security applications.

 

In the first part of this talk, I will introduce a miniaturized resonant chemical sensor based on a 50-MHz capacitive micromachined ultrasonic transducer (CMUT). With a high mass sensitivity of 3.3 ag/Hz, this CMUT-based chemical sensor achieves excellent volume sensitivity of 21 pptv/Hz to dimethyl methylphosphonate (DMMP), a common simulant for sarin gas.

 

In the second part, I will introduce a direct application of the mesoporous silica thin-film on a CMUT for relative humidity and CO₂ detection. Using mesoporous silica thin-film with a pore size of  ~11 nm, this sensor achieves one of the lowest volume resolutions and a sensitive detection of 5.1 × 10^-4%RH/Hz to water vapor in N₂. In addition, a mesoporous thin-film that is functionalized with an amino-group is directly applied on the resonant sensor, which exhibits a volume sensitivity of 1.6 × 10^-4%/Hz and a volume resolution of 1.82 × 10^-4% to CO₂ in N₂.

 

In the last part of my talk, I will focus on the sensor interface circuitry for CMUT and discuss the frequency noise analysis of CMUT-based oscillators. Specifically, I will introduce a multi-channel interface integrated circuit (IC) implemented using 0.18-um CMOS technology, which results in reduced area and power consumption for each channel. Two-channel detection of relative humidity is demonstrated using this circuit.

 

Analytical Room(Outside of Litho area) Scheduled Shutdown 3/7

Hello Lab-members...

   This Email is to notify you that the Analytical Room(Jerabic Room), just outside of the Litho Area will be shut down tomorrow(3/7). The area will be shutdown so that the contractors from AGC can re-hang the HEPA filters located in the ceiling. The work is scheduled to begin at 6:30 am and is expected to take 4 to 6 hours to compete the repairs. During this time, the room will be off limits to all lab-members for safety reasons. Please schedule your time accordingly and make alternate plans during this shutdown. The following tools will be unavailable during this time: Tencor Alphastep, Nanospec2, Tencor P2, Tencor Stresstest, Rudolph Ellipsometer and Tencor Particle Counter. A follow-up Email will be sent out when the construction work is completed. We apologize for the inconvenience.

      Thanks.... Your SNF Staff

Lab Access Restriction, Thursday 5:30-9 am

Dear labmembers --

As part of the new nSiL lab fit up, the contractors will be using a
crane to lift a large fan unit onto the roof of the lab. For safety
reasons, during this time, no one is allowed in the cleanroom, in the
Receiving area, or in the adjacent rooms (Maintenance Shop, Wafersaw
room and Test room). Access to the corridor leading to the lab and to
the receiving area out back will be blocked.

Access will be blocked from 5:30 am on Thursday, March 8, until the fan
and crane are secured. The contractors plan to be done by 9 am, if not
sooner.

With a few exceptions, no unattended processes may be run during this
time -- because if anything goes wrong, no one will be able to respond.
If during this time you wish to run a process unattended (Raith Ebeam
write, for example), send a request to the tool owner and copy me.
Otherwise, processes ongoing during this time may be stopped.

Many apologies for the inconvenience. This is the last major phase of
the renovation and plans are to complete the nSiL by the first week in
April. We anticipate more disruptions to normal lab operations in the
next weeks, but they should be smaller and you will be updated as plans
are confirmed.

Thanks for your attention --

Your SNF Staff

--
Mary X. Tang, Ph.D.
Stanford Nanofabrication Facility
Paul G. Allen Room 136, Mail Code 4070
Stanford, CA 94305
(650)723-9980
mtang@stanford.edu
http://snf.stanford.edu

EE412 mentoring for spring 2012 class

hello labmembers,

the snf is almost fully back online and many new pieces of equipment and upgraded equipment are now available.  A prime opportunity for interested an motivated students to make a major contribution to the snf community through EE412 projects.  if you are interested in doing a 412 project in ALD i have several ideas and welcome more.  ideas are floating around for several other projects and equipment, in case you are looking for a mentor.

the best ticket to a quality 412 project is pre-planning because the course is so short due to the quarter system.  

if you are interested in working with me on a 412 project (ALD or otherwise) in the spring 2012 quarter, you must meet with me to secure a plan before the quarter begins.  in fact, ideally i would like to involve dr. john bumgarner (SNF director of operations) in the project scope conversation before the spring quarter as well, so sooner is better than later to start the discussion.

feel free to email or just drop by my office (allen 127x).

j

Low temperature bonding

Hi All,

I'm looking for a low temperature method to connect our IC to etched copper on PET. The bond pads on the die are Al and are 100x100um in size. The connection must be low resistance to both Al and Cu, and the bonding temperature must be <150C. Al ultrasonic wirebonding has been attempted, but ultrasonic can damage our die and the connection to copper can be variable. Any and all suggestios are welcome.

Thanks for the help,

Aditi Chandra
Kovio, Inc.

Found USB Stick In the Litho Area by the Quarter Track

Dear All,

 

If you have misplaced your Gray USB stick with the name Kingston on it – it was found in the Litho area near the Quarter Track.  Now it’s at my desk if you would like to come claim it.  I’m in cubicle number 41 near the doors closest to all the outside construction.

 

Maureen

Re: Nathan Klejwa Defense - Tuesday March 6 from 4-6pm in 202 Packard

Dear Labmembers,

Nathan Klejwa from my group is defending tomorrow afternoon from 4-6 in
202 Packard. Be there to cheer him on and learn about alternatives to
photolithography for prototyping and perhaps, manufacturing, low-cost
microsystems.

Roger

Here's his title and brief abstract:

Rapid Microsystem Prototyping

This work focuses on developing tools and processes to decrease the time
it takes to create microsystem prototypes by using printing and CNC
micromilling as mask-free "rapid prototyping" alternatives to
photolithography, deposition, and etching. Printing allows for the
maskless deposition of a patterned polymer layer in a matter of seconds,
which can be used for etch masking, liftoff patterning, or as an active
microstructural material. CNC micromilling acts as a highly selective
and anisotropic etch for difficult-to-etch materials like PDMS, without
the need for a masking layer. These two processes can individually
create microdevices such as laser scanners or pump-free microfluidic
systems, but when combined allow for the creation of complex,
electromechanical devices in days rather than months. In addition to
their use for prototyping, these processes can be extended into mass
production for extremely low-cost, large-area, reel-to-reel compatible
polymer-based devices.