Looking for advice on wafer bonding

Dear labmembers, 

I have been doing silicon-silicon wafer bonding for years using gold-silicon eutectic bonding.  While this is a reasonable wafer bonding method,  it leaves much to be desired.  Briefly,  the bond is not very strong - frequently even ultrasonic cleaning can break the bonded chip stack. 

I am looking for a better silicon-silicon wafer bonding process.  Factors to consider include process simplicity, bonding yield/strength, tolerance to dust particle, etc.  If every step can be performed at SNF,  it would be always better.  A lower temperature process is desirable. 

Your kind advice is greatly appreciated. 

Ben Jian

RE: Shadow Mask

Here is another source,

 

1" shadow mask 4 mil stainless substrate.

 

Mark Devereaux

71 Willie Street

Lowell MA 01854

 

T:978-805-5000

F:978-805-5049

 

They made 100, 200, 500um lines with 350um spacing for us.

 

 

---

From: jrbexbox@gmail.com [mailto:jrbexbox@gmail.com] On Behalf Of Rebecca Taylor
Sent: Monday, June 30, 2008 5:24 PM
To: Jung-Yong Lee
Cc: snf
Subject: Re: Shadow Mask

Dear Jung-Yong,

I've been working with a company in San Jose called Directed Light.  They're lasercutting a few masks for me out of .005" Kapton film.  I believe their spot size is between 10 and 25 microns-- I need to do more measures on my devices to verify.  

If you're interested in Kapton film-based shadow masks, I can send along the contact information.

best,

-rebecca taylor

--
Rebecca Taylor
Graduate Research Assistant
Microsystems & Biomechanical Computation Groups
Mechanical Engineering
Stanford University

Problem p5000etch SNF 2008-06-30 18:35:26: Encoder Error 209 Robot Extension Error

I was using Ch C std etch. The robot picked the wafer and was transferring it to Ch C. Then "Encoder error 209, encoder pulses on ROBOT EXTENSION Axis, Canoot Complete - ROBOT EXTENSION position is not known" message popped up in red.
At the moment, Ch C monitor etch screen says "Waiting for blade exit" as well as the red error message described above.
I'll try to find someone whocan fix it. If you are able to take the wafer out (it has a piece stuck with kapton tape) please send me an email at kocabas@stanford.edu. I will be in the e-beam room until 9pm today (June 30, Monday), too.
The system is yellow lighted, and Ch C is off until the wafer can be taken out.
Ekin

Re: Shadow Mask

Dear Jung-Yong,

I've been working with a company in San Jose called Directed Light.  They're lasercutting a few masks for me out of .005" Kapton film.  I believe their spot size is between 10 and 25 microns-- I need to do more measures on my devices to verify.  

If you're interested in Kapton film-based shadow masks, I can send along the contact information.

best,

-rebecca taylor

--
Rebecca Taylor
Graduate Research Assistant
Microsystems & Biomechanical Computation Groups
Mechanical Engineering
Stanford University

Re: Shadow Mask

We've used Towne Technologies for features down to 50um with success.

http://townetech.com/

Jung-Yong Lee wrote:
> Hi, does anyone know any decent shadow mask makers? The shadow mask is
> for metal deposition, and the smallest size is 0.004". Thanks.
>
> Jung-Yong

--

*****************************************
Colin Reese
PhD Candidate
Stanford University
Department of Chemical Engineering
Office: 650 725 3144
Mobile: 503 888 6154
email: ccreese@stanford.edu
*****************************************

Shadow Mask

Hi, does anyone know any decent shadow mask makers? The shadow mask is for metal deposition, and the smallest size is 0.004". Thanks.

Jung-Yong

PhD Oral Examination annoucement

University Ph.D. Oral Examination

Title:  On-Chip Isotachophoresis Assays for High Sensitivity  Electrokinetic Preconcentration, Separation and Indirect Fluorescence Detection

Candidate: Tarun Khurana

Advisor: Prof. Juan G. Santiago
Department of Mechanical Engineering

Time: Wednesday,  July 2nd  2008,  2:00 pm

refreshments served at 1:45 pm

Location: McCullough building, room 122 (map attached)


Abstract:
Microfluidic devices have been particularly attractive for separation based chemical and biological analysis since the small length scales bring fundamental improvements in reagent volume, analysis time, resolution and separation efficiency.  However, smaller length scales and volumes are also associated with lower detection sensitivity and therefore, microchip electrophoresis analysis is often less sensitive and is more commonly used for fluorescent analytes since fluorescence detection platform offers higher sensitivity.  This presentation will focus on leveraging an electrophoresis technique termed isotachophoresis (ITP) for improving the detection sensitivity of on-chip electrophoresis assays and extending its scope to non-fluorescent analytes.
    ITP is a robust sample preconcentration technique focuses analytes into zones that are ~10 µm wide. Such extreme compression of analytes results in drastic improvement in the detection sensitivity and resolution of electrophoretic separation system.  We present a theoretical and experimental study of dynamics of ITP preconcentration that helps identify and optimize experiment parameters to achieve high sample preconcentration      We have also demonstrated an indirect detection technique based on ITP to detect non fluorescent analytes on a standard fluorescence detection platforms.  We leverage ITP to preconcentrate and separate analytes into distinct analyte zones and use a set of fluorescent species with different electrophoretic mobilities to demarcate the boundaries of these analyte zones and thereby, indirectly detect the non-fluorescent analytes present.  We obtain ~1 µM detection sensitivity with this assay with high repeatability and have demonstrated indirect detection of a variety of analytes such as amino acids, organic acids and environmental toxins such as phenols and cresol.

---

Flynn PhD Thesis Defense, Tuesday July 1, 3PM

PhD Thesis Oral Examination

"Flow Boiling Instabilities in Microchannels"

Candidate: Roger D. Flynn

Advisor: Prof. Ken Goodson

 

Date: Tuesday, July 1

Time: 3:00PM, refreshments beforehand

Room CISX-101 (Auditorium)

http://campus-map.stanford.edu/index.cfm?ID=04-055

 

Abstract

 

There is a growing demand for compact high heat flux cooling in a number of components like microprocessors, LEDs and laser diodes.  Microchannel heat sinks are a natural solution, leveraging microfabrication to thin convection boundary layers for enhanced heat transfer in a package comparable in size to the cooled components.  Liquid flow microchannel heat sinks have recently been commercialized, cooling 250 W/cm², but much lower flow rates and pumping powers are achievable with flow boiling which utilizes the fluid’s latent heat of vaporization.  However, boiling produces instabilities which must be better understood and controlled before implementation is practical.  Instabilities have been well documented, particularly in nuclear reactor design, but confined bubble growth and short length scales in microchannels lead to a significantly different balance of forces which govern instabilities.

This work describes a unique set of experiments which enable decoupling and characterization of thermal and hydrodynamic microchannel flow instabilities.  Modeling and analysis are developed around data for a single channel and then applied to two parallel channels.  The dual channel system exhibits the same parallel channel instabilities observed in massive parallel channels, but with fewer coupled channel interactions.  Thermal and hydrodynamic instabilities are further deconvolved by MEMS fabricated dual channels with and without lateral heat conduction between channels.  Thermally isolated channels exhibit the worst case of hydrodynamic instability, leading to premature dryout, while thermally connected channels redistribute heat to stabilize flow boiling.  Appropriate scaling for each mechanism gives guidelines for design of a microchannel heat sink with stable flow boiling, fit for the most demanding high heat flux and space constrained applications.

 

SNF Process Clinic, Mon, 2-4/Special Guest, ASML's Keith Best

Greetings labmembers --

The next SNF process clinic will be Monday, June 30, from 2-4 pm. Keith
Best, Director of Special Applications at ASML, will be on hand to
answer any technical or process questions about the ASML -- he's
particularly keen on meeting anyone interested in the new 3D align
upgrade which was successfully qualified just last week. As usual,
Process staff will also be on hand to discuss your process and SpecMat
questions.

Bring your process flows, your MSDS sheets, whatever --

See you there --

Your Process Staff

Re: Comment p5000etch SNF 2008-06-27 09:01:42: Update

Processsed 24 wafer through each of the chambers with no single alarm.

Comment p5000etch SNF 2008-06-27 09:01:42: Update

Testing handler

Re: Problem p5000etch SNF 2008-06-26 09:12:50: Wafer did not drop on blade from Ch.A

Recovered user's wafer. Adjusted the wafer pickup position. Now cycling wafers.

Help Requested

Hello SNF Users,

I'm a grad student in Stacey Bent's lab in the ChE department.  I'm looking for a MegaOhmMeter that I could borrow for about an hour.  I don't mean a multimeter that measures megaohms or an impedance analyzer.  I mean specifically a device that can apply up to 1 kV across an insulative material and measure the resulting small current that would flow through it (and calculate the resistance) if it were defective.  I badly need this device to check whether or not the anode of our XPS gun is shorted to ground.  Until we can determine if the problem is with our gun or our gun controller, we cannot proceed with troubleshooting/repair.

Thank you so much,
Jessica Kachian

P.S.  An example of a MegaOhmMeter can be found here http://www.yesco.net/megaohmmeter.htm

Problem p5000etch SNF 2008-06-26 09:12:50: Wafer did not drop on blade from Ch.A

silicon 110 wafer?

Hi all,

Does anyone have a bare <110> Si wafer I can have? I'm trying to run some experiments on short notice, so if anyone can spare one that'd be a big help. Doping doesn't really matter.

Thanks much,
Dan

Re: Problem p5000etch SNF 2008-06-25 10:25:33: Ch.B. Wafer stuck

unloaded the user's wafer. Cycled 8 wafers with no problems.

Problem p5000etch SNF 2008-06-25 10:25:33: Ch.B. Wafer stuck

Run a dummy wafer this time before etching my real wafers. It too got stuck :(

Forest fire smoke ....

SNF Lab Members:

Once again, we seem to have the low-level smell of smoke in and around
the building and, as a result, in the lab. My guess is that, depending
on wind and atmospheric conditions, this may be an ongoing occurrence
for the next few days until the forest fires are fully extinguished.

Please be extra cautious in the lab under these conditions. It will
require extra care to distinguish "real" lab odors from the smell of the
smoke.

Thank you for your continued support,

John

Re: Problem p5000etch SNF 2008-06-24 15:15:41: Ch. B. Wafer did not drop on blade

Recovered wafer from chamber B.

Problem p5000etch SNF 2008-06-24 15:15:41: Ch. B. Wafer did not drop on blade

Re: Shutdown p5000etch SNF 2008-06-24 11:36:58: Unable to pickup wafer from cassette

Adjusted both cassettes to blade alignment. Cycled wafers with no problems.

Re: Problem p5000etch SNF 2008-06-23 09:19:48: wafer stuck

Handler failed for not being able to pickup a wafer during wafer cycling.

Shutdown p5000etch SNF 2008-06-24 11:36:58: Unable to pickup wafer from cassette

Lost Car Key

Dear lab members,

I lost my only car key somewhere, probably in the CIS building. If
anyone has seen a black car key, please let me know.

Thanks,

Chong

lost Stanford ID

I believe I dropped my ID somewhere inside the clean room. If any one
finds it, please send me an email.
Thanks,
Michelle Povinelli

Open Source software for mask editing - MAC, PC, Linux

Dear Labmembers,

In the spirit of supporting open source software, I just wanted to recommend the very nice open-source program LayoutEditor, which can be found at http://layout.sourceforge.net/

It is small and easy to use, and it works natively with GDS (mask) and DXF (autocad) file formats. It shows you what the mouse buttons will do at any given instance, and it also can display your mask layers as a stack in 3D. It's available for Windows, MAC, and Linux. If you need a program to edit or display your mask files on your own computer, then this program is the best alternative to L-Edit that I know - see screenshots below. L-Edit may still have better DRC and geometry flag checking - which you can do when you're mostly done with your design - but I have exclusively been using LayoutEditor for years now with good success.

Best regards,
Sebastian Osterfeld

Intermittent sliding lab door ...

SNF Lab Members:

We've had two reports of the inner sliding door (the one between the
inside of the lab and the gowning area) failing to open: once on Friday
and once today. On Friday, by the time we could look at it, it seemed
to be working again. Today, I got there in time to see that it, in
fact, would not open .... but power cycling it seemed to make it
functional once again. I've put in a request to facilities (because
they take care of that door) to take a look at it.

However, particularly in the event of a power failure or other
emergency, you should all be aware that you can ALWAYS get that door to
open by pushing outward on the metal frame on the left side near the
latch. That will cause the door to swing open (rather than slide open)
and you can get out. Also, the outer door to the hallway has a white
"Emergency Override" button on the right side of the door frame (at
about the height of the handle) that will allow that door to open
immediately, even if the inner door is open.

So, we will try to resolve the intermittent failure that we are seeing
on that inner door, but I wanted to make sure that you all know that you
can always get out of those doors even if they appear to not be functional.

Thank you for your continued support,

John

Problem p5000etch SNF 2008-06-23 09:19:48: wafer stuck

Error wafer did not drop on blade. The wafer is in the loadlock (it's not sitting on the blade properly, but it did come out of the chamber)

Re: Problem p5000etch SNF 2008-06-19 12:16:06: run button is not working

Found the cap sensor disable, enable cap sensor and
transfer wafer w/out problem. Also, added fomblin oil
on load lock pump it was low on oil and load will not
pump down.

Reminder: Labmembers' Meeting Today (Friday) at 11 am

Hi all --

Just a reminder that there's a Labmembers' Meeting today (Friday) at 11
am in the CISX 101 Auditorium. All are invited. Find out what the new
"spin etch" tool can do (located next to wbgaas). Get a sneak peak at
the new lab web site under development. Hear about new equipment and
process capabilities on the horizon. Be there and be aware --

Your SNF Staff

Problem p5000etch SNF 2008-06-19 12:16:06: run button is not working

-

Re: Problem p5000etch SNF 2008-06-18 15:45:39: Wafer stuck in Ch. B

The wafer is actually in the pocket blade, changed the
rotation and extension step count to +1 both axis.

Labmembers' Meeting, Friday, June 20, 11 am, CISX-101

Greetings labmembers --

Please come to the SNF Labmembers' meeting, this Friday, June 20, from
11 am - noon, in the CISX Auditorium. The agenda will be a review of
the status of the various programs and projects underway in the lab,
including:

- the new Wiki-based website
- updating the EE410 device process
- new equipment installations and upgrades
- and much more --

Be there and be aware!

Your SNF staff

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

Problem p5000etch SNF 2008-06-18 15:45:39: Wafer stuck in Ch. B

Wafer did not drop on blade.
Please put my wafert in the box in front of the machine. Thanks!

REMINDER- PhD Dissertation Defense for Luke Tang on June 19th

Department of Applied Physics
University PhD Dissertation Defense

Nanometre-Scale Photodetectors Enhanced by Optical Antennas

Liang (Luke) Tang

Research Advisor: Professor David A. B. Miller

June 19, 2008 @ 3:00 P.M.
in
Center for Integrated Systems (CIS-X), Auditorium, Room 101

Abstract

The use of optics to make connections within and between electronic chips has been the subject of research for over 20 years because it could solve many of the problems experienced in electrical systems. A critical challenge for the convergence of optics and electronics is that the micrometre scale of optics is significantly larger than the nanometre scale of modern electronic devices. In the conversion from photons to electrons by photodetectors, this size incompatibility often leads to substantial penalties in power dissipation, area, latency and noise. A photodetector can be made smaller by using a subwavelength active region which, however, could result in very low responsivity because of the diffraction limit of the light.

In our first approach to tackle this problem, we use a C-shaped nano-aperture antenna in a thin metal layer to enhance the photocurrent response of a subwavelength photodetector. The work is the first demonstration of a plasmonic-enhanced semiconductor photodetector at near-infrared wavelengths. In our second approach, we exploit the idea of a dipole antenna from radio waves, but at near infrared wavelengths (~ 1.3 µm), to concentrate radiation into a nanometre-scale Ge photodetector. Despite the small antenna size (~ 380 nm long) and the different properties of metals at such high frequencies (~ 230 THz), the antenna has qualitatively similar behavior to the common radio-frequency half-wave Hertz dipole. It gives a relative enhancement of 20 times in the resulting photocurrent in the subwavelength Ge detector element, which has an active volume of 0.00072 _m3, two orders of magnitude smaller than previously demonstrated detectors at such wavelengths. Finally, we integrate an antenna-enhanced photodetector on a commercial CMOS chip, which is the first demonstration of any plasmonic effect in Si CMOS. Photodetectors are one of the most critical components in optoelectronic integration, and decreasing their size may enable novel chip architectures and ultra-low electrical and optical power operations.

--  

--++**==--++**==--++**==--++**==--++**==--++**==--++**==
apgradstudents mailing list
apgradstudents@lists.stanford.edu
https://mailman.stanford.edu/mailman/listinfo/apgradstudents

Re: Problem p5000etch SNF 2008-06-17 15:03:22: a offline and system frozen

Online chamber was able to cycled through chamber a
w/out problem.

Re: Problem p5000etch SNF 2008-06-17 09:59:02: encoder error

Homed storage eleavetor

Problem p5000etch SNF 2008-06-17 15:03:22: a offline and system frozen

Chamber A was offline. I didn't know. I ran the recipe and received an error. Now I can't change the mode from automatic to manual to release the cassette and get my wafer.

Re: Problem p5000etch SNF 2008-06-09 14:51:05: Ch.A intermittent handling problem

Problem p5000etch SNF 2008-06-17 09:59:02: encoder error

Ultra parallel quartz wafers from Hoya?

Hi all,

 

Does anyone have a Hoya quartz UP wafer that I could look at under an interferometer?  (or any comments on how flat/parallel they or other quartz wafers are?)  

 

Thanks,

-Meredith 

--
--------------------------------------------------
Meredith M. Lee
Stanford University
Ph.D. Candidate, Dept. of Electrical Engineering
President, Stanford Student OSA/SPIE

Center for Integrated Systems
420 Via Ortega, Stanford, CA 94305-4075
Fax: (650) 723-4659
mmlee@stanford.edu

Acid neutralization .... OK to use!

SNF Lab Members:

The sodium hydroxide tank for the acid waste neutralization system has
been filled. While facilities is still monitoring the condition of tank
#2 that caused excessive sodium hydroxide usage, we have been given the
"all clear" to resume normal processing activities. While there may be
some interruption in service later, depending on what they learn, for
the moment we may resume full wet bench operations.

Happy processing,

John

Re: Problem p5000etch SNF 2008-06-17 06:20:08: BCL3

Chiller set point has been reset and the pressure at the
bottle has stabilized. Currently 5.2 and climbing. Should be
ok to use now.

Problem p5000etch SNF 2008-06-17 06:20:08: BCL3

There is a problem with the BCL3 gas bottle chiller. It is not
heating and delivery pressure is less than 1 lbs. Do not
run any BCL3 until problem is fixed

Acid Waste Neutralizer down for the night

Please do not dump acids or bases at any of the wetbenches
tonight. The Neutralizer is down until the morning.
Cesar got the system back into spec manually, and
Tony Padilla came in from vacation to look at the system.
Jose will take care of it in the morning.

It's critical that no chemicals be dumped. If the pH
goes out of spec in the neutralizer tanks, then the
neutralizer must divert ALL water to a holding tank,
that will quickly fill up and overflow. Even if noone
is dumping water from the lab, the scrubbers and other
facilities continuously feed (almost pure) water to
the system. So if we upset the pH in the system even slightly,
we create a very bad overflow situation.

Re: Problem p5000etch SNF 2008-06-13 15:05:57: Robot has lost it's mind....

wafer recovered.

Re: Problem p5000etch SNF 2008-06-15 23:09:40: error again

The system lose zero position, re-teach robot zero positon
and cycled robot from storage to all chambers continously
to make sure robot arm goes back to zero position.

Does Anyone know Victor Andrade?

 

Dear All,

 

He dropped his Driver’s License and I have it at my desk.  I am in cubicle #41 on the first floor of the CIS building.

 

Thank you,

 

Maureen

 

Maureen Baran

Stanford Nanofabrication Facility

Lab Services Administrator

mbaran@stanford.edu

650-725-3664

 

PhD Dissertation Defense for Luke Tang on June 19

Department of Applied Physics
University PhD Dissertation Defense

Nanometre-Scale Photodetectors Enhanced by Optical Antennas

Liang (Luke) Tang

Research Advisor: Professor David A.B. Miller

June 19, 2008 @ 3:00 p.m.
in
Center for Integrated Systems (CIS-X), Auditorium room 101

Abstract

The use of optics to make connections within and between electronic chips has been the subject of research for over 20 years because it could solve many of the problems experienced in electrical systems. A critical challenge for the convergence of optics and electronics is that the micrometre scale of optics is significantly larger than the nanometre scale of modern electronic devices. In the conversion from photons to electrons by photodetectors, this size incompatibility often leads to substantial penalties in power dissipation, area, latency and noise. A photodetector can be made smaller by using a subwavelength active region which, however, could result in very low responsivity because of the diffraction limit of the light.
In our first approach to tackle this problem, we use a C-shaped nano-aperture antenna in a thin metal layer to enhance the photocurrent response of a subwavelength photodetector. The work is the first demonstration of a plasmonic-enhanced semiconductor photodetector at near-infrared wavelengths. In our second approach, we exploit the idea of a dipole antenna from radio waves, but at near infrared wavelengths (~ 1.3 µm), to concentrate radiation into a nanometre-scale Ge photodetector. Despite the small antenna size (~ 380 nm long) and the different properties of metals at such high frequencies (~ 230 THz), the antenna has qualitatively similar behavior to the common radio-frequency half-wave Hertz dipole. It gives a relative enhancement of 20 times in the resulting photocurrent in the subwavelength Ge detector element, which has an active volume of 0.00072 _m3, two orders of magnitude smaller than previously demonstrated detectors at such wavelengths. Finally, we integrate an antenna-enhanced photodetector on a commercial CMOS chip, which is the first demonstration of any plasmonic effect in Si CMOS. Photodetectors are one of the most critical components in optoelectronic integration, and decreasing their size may enable novel chip architectures and ultra-low electrical and optical power operations.

--  

--++**==--++**==--++**==--++**==--++**==--++**==--++**==
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Ge Spin-Etch Clean Tool

All,

The process engineer from Laurell Technologies will be available from
9-11am on Wednesda,y June 18th to explain the new Spin-Etch tool SNF
just installed. Please take the time to stop by and get your
questions answered from the expert.

Regards,
Ed

Problem p5000etch SNF 2008-06-15 23:09:40: error again

as soon as i change the mode from manual to automatic, an error 'storage elevator axis is moving' appears. it has happened 3 times already and i can't use the machine.

SNF Process Clinic, Monday, June 16, 2-4 pm

Greetings Labmembers --

Process Clinic, this coming Monday, June 16, from 2-4 pm in the cubicle
area near CIS 41. Bring questions about processing and process flow,
mask layouts, and new materials and chemicals. Staff and experienced
labmembers will be on hand to offer suggestions. SpecMat will convene
at 3 pm to review new material/chemical requests.

Your SNF Staff

Comment p5000etch SNF 2008-06-15 01:29:16: recovered wafer from Ch. A.

Fwd: last two bottles of 50:1 HF left.

All,

The chemical pass-through has been replenished. Please adhere to the
posted frequency for changing the chemicals.

The 4:1 sulfuric/peroxide clean should be changed once every five days.
The 5:1:1 H2O:H2O2:HCl hot pot should be changed every four hours.
The 50:1 HF tank should be changed once/day.
The 6:1 BOE is changed once per month or on an as-needed basis.

Regards,
Ed

>Subject: last two bottles of 50:1 HF left.
>

Problem p5000etch SNF 2008-06-13 15:05:57: Robot has lost it's mind....

This should be a shutdown, but since it is Fri and a weekend is ahead perhaps there is someone who can recover from this error.
Error message was 'wafer not on blade'- it was, then 'robot extension position is not known'.
I don't care about getting this wafer back; it was a training wafer.

Late Announcement: Ph.D. Oral Examination - Alvin Barlian

Microfabricated Piezoresistive Shear Stress Sensors for Underwater Applications

A. Alvin Barlian

Department of Mechanical Engineering, Stanford University

Ph.D. Oral Examination

Thursday, June 12, 2008 (Packard 101), 9AM

 

Abstract

Shear stress at the solid-fluid interface is a frequently studied parameter in fluid dynamics because of its relevance to many engineering applications, such as those in aerodynamic and hydrodynamic design. Shear stress measurements are also critical in biomedical and environmental science research. For example, shear stress data lead to improved understanding of fluid flow physics in cardiovascular systems and coral reef ecologies.

We present the design and characterization of a piezoresistive floating-element shear stress sensor. Conventional and oblique-angle ion-implantation techniques were used to form piezoresistors on the top and sidewall surfaces of the tethers. Hydrogen anneal technology was used to smooth sidewall scallops commonly seen in the Deep Reactive Ion Etching (DRIE) process and to reduce the noise in sidewall piezoresistors. A microfabricated piezoresistive cantilever was used to characterize the in-plane sensitivity of the sensor, while Laser Doppler Vibrometry was used to characterize its out-of-plane sensitivity.

The SiO₂/Si₃N₄/SiO₂ triplex layer and Parylene C were used as passivation schemes in two underwater experiments. The first experiment used a cylindrical water tank sitting on a rotating table to produce solid body rotation. The second experiment used a gravity-driven water flume to create a uniform, fully-developed flow over the sensor. Polymer flip-chip flexible interconnects were fabricated and used for the packaging of the sensor in the second experiment.

Piezoresistors formed using the oblique-angle ion-implantation technique required a thermal annealing step to activate dopants, hence increasing junction depth and reducing sensitivity. A novel sidewall epitaxial piezoresistor fabrication process, using selective deposition, is demonstrated for in-plane sensing applications. Early findings on electrical and mechanical characteristics are presented.  

NOTE: DEFENSE TIMING CHANGED TO 11:30AM , 13 June 2008

Ph.D. Thesis Oral Examination
"Energy Loss Mechanisms in Micromechanical Resonators"
Advisor: Prof. Thomas W. Kenny and Prof. Kenneth E. Goodson

Date: Friday, June 13th
Time: 11:30 pm (Refreshments beforehand)
Venue: CISX-101 (Auditorium)
http://campus-map.stanford.edu/index.cfm?ID=04-055

Keywords: energy loss mechanisms, micromechanical resonators,
thermoelastic dissipation, Akhiezer effect, entropy generation
minimization, quantum limit

Abstract:

Micromechanical resonators have the potential to replace quartz
crystals for timing and frequency references owing to their small
form factors, better aging stability and CMOS scalability. Quality
factor, an important performance characteristic of all resonators,
determines limits for system characteristics like close to carrier phase
noise, stability and motional impedance.
Thus, for most applications we would like to design for the maximum
achievable quality factor, and this requires good understanding of the
energy loss mechanisms that limit the performance of modern
micromechanical resonators. This work focuses on two such mechanisms:
Thermoelastic dissipation and Akhiezer effect.

Thermoelastic dissipation refers to the energy lost from a solid
due to flow of heat between regions of different volumetric changes.
This work presents a comprehensive entropic formulation
for quantifying energy loss due to thermoelastic dissipation. Entropy
generation minimization, and therefore energy loss minimization, will be
demonstrated through several case studies including simple fixed-fixed
beams, simple fixed-fixed beams with
slots, composite beams and various bulk mode structures. We compare
our simulations against experimental evidence for confirmation of
modeling technique.

Certain bulk mode resonator structures will be shown to be immune
to thermoelastic dissipation. Akhiezer effect sets the ultimate
quantum limit of minimum achievable energy loss in dielectric
micromechanical resonators. It will be shown that the current
micromechanical resonators found in literature are very close to
this limit. Finally, recent results of microresonators designed
to operate close to Akhiezer effect limit will be discussed.

Borrowing silicon wafer with thick silicon oxide

Dear All,

Does anyone have extra 4" silicon wafer with thick silicon oxide on
top(>100nm) I can borrow? I sort of desperately need this kind of
wafer, and would certainly return the favor later on in some ways.

Many thanks

Linyou

--
Linyou Cao
PhD candidate
Dept. of Mater. Sci.and Engin., Brongersma Group
President&Co-founder
Stanford Nanoscience&Nanotechnology Society
Stanford University

Saurabh Chandorkar Thesis Defense - 12:30pm Friday, 13 June 2008

Ph.D. Thesis Oral Examination
"Energy Loss Mechanisms in Micromechanical Resonators"
Advisor: Prof. Thomas W. Kenny and Prof. Kenneth E. Goodson

Date: Friday, June 13th
Time: 12:30 pm (Refreshments beforehand)
Venue: CISX-101 (Auditorium)
http://campus-map.stanford.edu/index.cfm?ID=04-055

Keywords: energy loss mechanisms, micromechanical resonators,
thermoelastic dissipation, Akhiezer effect, entropy generation
minimization, quantum limit

Abstract:

Micromechanical resonators have the potential to replace quartz
crystals for timing and frequency references owing to their small
form factors, better aging stability and CMOS scalability.
Quality factor, an important performance characteristic of all
resonators, determines limits for system characteristics like
close to carrier phase noise, stability and motional impedance.
Thus, for most applications we would like to design for the
maximum achievable quality factor, and this requires good
understanding of the energy loss mechanisms that limit the
performance of modern micromechanical resonators. This work
focuses on two such mechanisms: Thermoelastic dissipation and
Akhiezer effect.

Thermoelastic dissipation refers to the energy lost from a solid
due to flow of heat between regions of different volumetric
changes. This work presents a comprehensive entropic formulation
for quantifying energy loss due to thermoelastic dissipation.
Entropy generation minimization, and therefore energy loss
minimization, will be demonstrated through several case studies
including simple fixed-fixed beams, simple fixed-fixed beams with
slots, composite beams and various bulk mode structures. We compare
our simulations against experimental evidence for confirmation of
modeling technique.

Certain bulk mode resonator structures will be shown to be immune
to thermoelastic dissipation. Akhiezer effect sets the ultimate
quantum limit of minimum achievable energy loss in dielectric
micromechanical resonators. It will be shown that the current
micromechanical resonators found in literature are very close to
this limit. Finally, recent results of microresonators designed
to operate close to Akhiezer effect limit will be discussed.

"Venture" Clinic - Friday, June 13, 11 am, CIS 101

Dear Labmembers:

Are you thinking about starting a company to commercialize your research?

Shahin Farschi, an Associate from Lux Capital, will be moderating a Venture Clinic, from 11-12, this Friday, June 13, in CIS 101. The aim of the clinic is to provide an informal forum for researchers interested in brainstorming with a venture capitalist on ways to commercialize research. Technical discussions should be limited to what has been already disclosed or published.

For more information, contact:

Shahin Farshchi, Ph.D.
Associate
Lux Capital Management, LLC
T: 925.323.2784
http://www.luxcapital.com

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

Renata Melamud Thesis Defense - 9am Friday 06/13/08

Renata Melamud
Ph.D. Thesis Oral Examination
"Temperature Insensitive Microelecromechanical Resonators"
Advisor: Prof. Thomas Kenny

Date: Friday, June 13th
Time: 9:00 am (Refreshments beforehand)
Place: CISX-101 (Auditorium)
http://campus-map.stanford.edu/index.cfm?ID=04-055

Abstract:

Silicon resonators for frequency reference applications capitalize on
the size and cost advantages of silicon processing. Start-ups developing
silicon resonators, such as SiTime, Discera, and Silicon Clocks, seek to
displace the $2.5 billion quartz crystal frequency reference market that
is at the core of modern electronic devices. However, unacceptable
frequency deviations caused by the temperature dependence of silicon's
material properties prevent these resonators from competing with quartz
resonators in high precision applications.

This work describes the design, fabrication, and testing of silicon -
silicon dioxide composite resonators whose temperature sensitivity is
comparable to quartz crystal resonators. The optimization of the
composite resonator demonstrates a thirty-fold reduction in
frequency-temperature sensitivity compared to uncompensated silicon
resonators. These temperature insensitive devices are single anchored
flexural mode resonators, are isolated from packaging stresses, and are
hermetically sealed in a CMOS compatible wafer-level encapsulation
technology. In conjunction with active temperature compensation schemes,
such as those employed in the quartz industry, this passive technology
enables silicon-based frequency references to surpass the size and power
limitations of quartz crystals in high precision applications.

Problem p5000etch SNF 2008-06-09 14:51:05: Ch.A intermittent handling problem

Does not seem to fail when using bare silicon wafer. Need to obtain wafers with a metal film.

Re: Problem p5000etch SNF 2008-06-09 12:56:32: wafer stuck in chamber A

Recovered the user's wafer and placed in container. Ran 16 wafers using the user's recipe with no problems.

Problem p5000etch SNF 2008-06-09 12:56:32: wafer stuck in chamber A

Mechanical post CMP scrub

Hello,

I am looking for a post (metal) CMP mechanical brush scrub cleaning service preferably in Silicon Valley. Something on the lines of an Ontrak brush scrub for 4" wafers would be very useful.

Thanks,
Arvind Kamath
Kovio Inc.

Re: Problem p5000etch SNF 2008-06-06 20:34:30: I cannot get my wafer

Re: Problem p5000etch SNF 2008-06-06 21:16:37: more..

The system software locked up, none of the icon will
response, had to cold reset the tool and removed wafer from
chamber B. I checked the wafer placement on chamber B
and it was off by 15 step count for extension drop and
10 count for extension pick up. Also, top off both hxt#1 and 4
it was alarming for low water level.

Problem p5000etch SNF 2008-06-06 21:16:37: more..

Gave an error - "Wafer did not drop on blade" in Chamber B.
Please look into this problem.

Problem p5000etch SNF 2008-06-06 20:34:30: I cannot get my wafer

I cannot get my wafer from chamber B.

Acid Use and Courtesy at Wet Benches

Hi all --

Just two reminders:

1. Check acid change frequency and to log your acid changes.  According to the wbdiff operating procedures:

• The 4:1 sulfuric/peroxide clean should be changed once every five days.
• The 5:1:1 H2O:H2O2:HCl hot pot should be changed every four hours.
• The 50:1 HF tank should be changed once/day.
• The 6:1 BOE is changed once per month or on an as-needed basis.

With the pass through fully stocked this afternoon, this should be more than sufficient for the weekend.  Please be judicious in your use of acids.

2.  Ask before sharing a wet bench.  The person who has the bench enabled is responsible for the bench, and therefore, your use if you share.  The person enabled has priority access -- and may ask you to enable over him/her.

Thanks for your attention --

Your SNF staff

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

Re: Problem p5000etch SNF 2008-06-05 11:55:31: chamber B

Chamber B place back online by users.

Missing 3 inch Wafers in single wafer holders

Hi,

Sorry for bothering.

Has anyone seen two 3-inch single wafer holders with label "Wafer 4"
and "Wafer 5"
on top of them recently?
Please let me know if you ever saw these kind of 3 inch wafer holders.
Thank a lot~~
Best,

Erik

SNF Process Grand Rounds

Hi all --

Just a reminder -- Process Grand Rounds today, at 11:30, in CIS 101.
1. Process Brainstorming: bring your process questions to pose to the
gang.
2. Quality Circle Update
3. Maskmaking with LEdit tutorial

M

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

New Lab Practices, effective Monday, June 9

Dear Labmembers:

Over the past few months, Quality Circles comprised of process and maintenance staff and students have been meeting regularly with the goal of defining ways in which we can improve our lab.  A lot of activities and programs have come out of these meetings – and we would like to inform you of two of them, scheduled to begin next week.

 

First: Name tags.  Starting Monday, we will expect everyone to begin wearing name tags in the lab.  Blank tags will be provided in the gowning room and are colored coded to distinguish labmembers from staff and from visitors.  With 230+ labmembers making use of the lab every month, it’s hard to know who everyone is, especially with bunnysuits on.  We hope this helps make it easier to find who that mystery Coral login “mrxyz” with the late innotec reservation is.  And we hope it will help reduce anonymity and improve personal accountability in the lab.

 

Second:  The shadowing program.  Starting Monday, labmembers wanting to be qualified on most wet benches and furnaces will be required first to observe a qualified labmember operate the system.  Shadowing forms will be available in the gowning room and will include some advice on shadowing courtesy.  For you experienced users, please be aware that new labmembers may scan through Coral reservations looking for someone to observe:  this may be you.  You have the right to refuse... but we want to encourage everyone to contribute and to use this as an opportunity to get to know, work with, and better train the next generation of labmembers.  And if you would like to be qualified on any of the automatic wet benches or furnaces, contact the appropriate staff member as usual; you’ll be given instructions, forms, and training materials.

 

These are only a couple of the many activities, projects, and programs coming out of the Quality Circles.  If you would like to participate in any of these (Furnaces, Litho, Etch, Metals, RTA’s, and Epi), please come to a meeting (most are held in CIS 201, but contact a staff member to confirm).  These are biweekly and schedules are posted on the whiteboard outside the gowning room. 

 

Thanks for your attention –

 

The SNF Quality Circles

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

Problem p5000etch SNF 2008-06-05 11:55:31: chamber B

appears as offline for maintenance

SNF Process Grand Rounds, 6/6/08, 11:30 am, CIS 101

Hi all --

It's that time again, the SNF Process Grand Rounds. Time for:
- Process brainstorming for anyone who'd like to pose a process question.
- Review of Quality Circle activities.
- And, if anyone is interested, a tutorial on using LEdit for mask layouts.

We'll be in CIS 101 at 11:30. Pizza will be on hand. Hope to see you
there.

Your SNF Process staff

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

Found USB Stick on the First floor of the CIS Building

Dear Lab Mebmers,

 

If you have misplaced your USB memory stick in the last couple of days, please stop by my cubicle # 41 on the first floor of the CIS Building.  Be prepared to describe your lost item.

 

Thank you,

 

Maureen

 

Maureen Baran

Stanford Nanofabrication Facility

Lab Services Administrator

mbaran@stanford.edu

650-725-3664

 

Reminder: University Ph.D. Oral Examination - Wei Hu

High-Moment Synthetic Magnetic Nanoparticles for Biomedical Applications

Wei Hu
Materials Science & Engineering
Advisor: Prof. Shan X. Wang

Thursday, June 5th, 2008
9:30 AM (Refreshments served at 9:15 AM)
McCullough Bldg. Room 335

Abstract:

Superparamagnetic nanoparticles are widely used in biology and
medicine for applications which include biomolecule purifications and
cell separations, magnetic resonance imaging(MRI) contrast agents, and
bio-magnetic sensing. These nanoparticles are usually synthesized by
chemical routes, which are powerful but the size of nanoparticles are
typically below 20 nm due to the superparamagnetic limit. Beyond this
size, it is difficult to attain monodispersity and the onset of
ferromagnetism results in coercivity,
remanent magnetization and consequently magnetically induced
agglomeration. Magnetic nanoparticles with higher moments are often
desired to produce large signals or to avoid restrictive requirements
for high magnetic field gradients in separations. One conventional
solution is to incorporate numerous magnetic nanoparticles into larger
composites using matrices comprised of dextran or silica. However,
there are still limitations associated with controlling the
monodispersity, magnetic response and variations in the number and
size of the embedded nanoparticles.

In this talk, I'll present the physical fabrication of sub-100 nm
monodisperse disk-shape synthetic nanoparticles with high
magnetization ferromagnetic multilayers (e.g. Co-Fe alloy) using
nanoimprint lithography (NIL) and high vacuum deposition, followed by
release and stabilization of nanoparticles in solution.
Antiferromagnetic interlayer interactions are exploited to achieve
zero remanence and thus these nanoparticles are termed synthetic
antiferromagnetic (SAF) nanoparticles, which posses magnetic moments
well above those typical of superparamagnetic nanoparticles.

Unlike the chemical synthesis of magnetic nanoparticles, physical
fabrication enables accurate control of particle shape, size and
composition, and thus synthetic nanoparticles possess a lot of
interesting properties which are not readily accessible to
conventional superparamagnetic nanoparticles. For example, I
demonstrate SAF nanoparticles with adjustable saturation fields, which
are desired for multiplex magnetic labeling in biodetection or
multiplex cell sorting. Their high magnetic moments afford great ease
for magnetic manipulation in solutions with only modest field
gradients, which
is highly desired for magnetic sorting. Metallic synthetic
nanoparticles strongly scatter light and can be individually tracked
in solution under optical microscopy.

To further evaluate their application potential for biomedicine, we performed
bio-magnetic detection with streptavidin functionalized SAF
nanoparticles. A low concentration of analyte DNA molecules at 10 pM
was clearly detectable. MRI measurements of nanoparticle enhanced
proton transverse relaxation revealed that SAF nanoparticles are
promising as contrast enhancement agents. In addition, hysteresis
measurements indicate that magnetic nanoparticles with vortex domain
structure (a second type of synthetic nanoparticles) could be
efficient heating elements for magnetic nanoparticle hyperthermia.

Last but not least, large scale fabrication of SAF nanoparticles with
low cost and high throughput is achieved using self-assembled stamps
and a polymer sacrificial layer with the assistance of batch-process
thermal evaporation. This fabrication technique is ideal for producing
multi-modal nanoparticles by exploiting layers with unique magnetic,
optical, radioactive, or electronic properties.
--
Wei Hu
Ph.D. Candidate
Department of Materials and Engineering
Stanford University

Fwd: University PhD Disseration Defense for Ilya Fushman

Dear Labmembers,

I'd like to invite you to attend my defense. 

Please see the email below.

-ilya

---------- Forwarded message ----------
From: Claire Nicholas <claireni@stanford.edu>
Date: Tue, Jun 3, 2008 at 8:02 AM
Subject: Re: University PhD Disseration Defense for Ilya Fushman
To:
Cc: apgradstudents@lists.stanford.edu, apfaculty@lists.stanford.edu

Department of Applied Physics

University PhD Dissertation Defense

Quantum Dots in Photonic Crystals: From Quantum Information Processing to Single Photon Nonlinear Optics

Ilya Fushman

Research Advisor: Professor Jelena Vuckovic

5 June 2008 @4:15 p. m.

in

Applied Physics Building,  Room 200

Abstract

Photonic crystal cavities have emerged as one of the leading technology platforms for classical and quantum information processing with photons. These cavities possess extremely small optical volumes and high quality factors, which result in long photon storage times and high field intensities inside these nano-resonators. The field intensities due to single photons inside such resonators are significant, and allow the exploration of light-matter interaction at the single photon level. Furthermore, these devices are fabricated in standard high index semiconductors, and thus benefit from existing technologies, scaling, integration and mass production. The combination of photonic crystals with optically active materials such as quantum dots and quantum wells offer the possibility of exploring novel regimes of light-matter interaction and the implementation of information processing devices.
We have recently demonstrated that the presence of a single semiconductor quantum dot inside a photonic crystal cavity can strongly modify the transmission of photons through the resonator. [1] Furthermore, due to the enhancement of the electromagnetic field intensity, the nonlinear properties of a single quantum dot can realize interactions between photon streams at the single photon level. We have exploited this effect to demonstrate a controlled phase shift interaction between photons, which serves as a proof of concept for quantum logic with photons on a semiconductor chip. [2] We have also shown that such cavities are extremely sensitive to local changes in refractive index, and can be used to realize all-optical modulation at high rates exceeding 20GHz, with applications to classical information processing. [3] The speed of such modulators is limited by the free-carrier lifetime of electron-hole pairs inside the semiconductor, which is greatly reduced relative to the bulk value by the large surface-area to volume ratio of photonic crystals.

[1] Controlling Cavity Reflectivity With a Single Quantum Dot, Dirk Englund, Andrei Faraon, Ilya Fushman, Nick Stoltz, Pierre Petroff, Jelena Vuckovic, Nature, vol. 450, number 7171, pp. 857-861 (2007)
[2] Controlled Phase Shifts with a Single Quantum Dot, Ilya Fushman, Dirk Englund, Andrei Faraon, Nick Stoltz, Pierre Petroff, Jelena Vuckovic, Science, vol. 320, number 5877, pp. 769-772 (2008)

[3] Ultra Fast Nonlinear Optical Tuning of Photonic Crystal Cavities, Ilya Fushman, Edo Waks, Dirk Englund, Nick Stoltz, Pierre Petroff, and Jelena Vuckovic, Applied Physics Letters, vol. 90, article 091118 (2007) (arXiv:physics/0611303)

--  

--++**==--++**==--++**==--++**==--++**==--++**==--++**==
apgradstudents mailing list
apgradstudents@lists.stanford.edu
https://mailman.stanford.edu/mailman/listinfo/apgradstudents

--
Ilya Fushman
Applied Physics
Stanford University
cvitae.org/ilya/

Chemicals have been stocked ....

SNF Lab Members:

The chemical shortage of sulfuric, peroxide, and 50:1 in the passthrough
has been alleviated ....

Happy processing,

John