University of Houston Nanofabrication Facility

07/26/2022

The names of nearly 30,000 people whose work made NASA's Artemis I mission possible will fly inside the Orion spacecraft on its upcoming journey around the Moon.

07/26/2022

https://stories.uh.edu/2022-microchips-space/index.html

When NASA’s Artemis I mission blasts off later this year, it won’t include people, but it will include 80 microchips with the names of the 30,000 team members who made the mission possible. The microchips were created at the University of Houston.

01/23/2015

Recently we upgraded the control system, user interface software and computer for the RIE 100 system. Everything was developed in house. This enabled us to fix a failing equipment and provided us the experience necessary to automate some of the equipment that requires manual operation such as the Ar Mill and the Ebeam Evaporator.

This development project initially began with the goal of simply replacing a failing control system. However, during the design and development phase, I was in the unique position of the software developer and the end user. This expedited the development cycle and it also allowed me to develop a software architecture that can support features that are suitable for the needs of a research environment. Here are some features I'd like to highlight:

1. Graphical process indicator - Graphs are used to show 15 seconds of process data. This will reveal the stability of a process. The attached photo is a screen shoot of a running process. Significantly, one can observe the process pressure stabilizing and it takes less than 1 second for the plasma to ignite and stabilize.

2. Process logging - A log will be generated whenever a process is run. Process data is acquired every 1/10 of a second. The log file is saved in an open format so that it can be analyzed by anyone.

3. Process log viewer - The entire process can be loaded and graphed to quickly analyze the long term stability of a process.

4. Help - Tool tips and help content is available to explain the various process controls.

There were some features that didn't make it to the release due to time constraints, but the software is designed to support those features if they are to be implemented in the future. In a future release, I'd like to introduce equipment health monitoring and self-maintenance capabilities. Routine work is something that computers can do much better than us.

The software was developed using LabVIEW 2013. The control system used was a LabVIEW cRIO (shown inside the computer case). LabVIEW object oriented programming was used to facilitate development, troubleshooting, maintenance, updates and sharing.

12/13/2014

After a few weeks of using the new ion mill source, we quickly realize that the wafer is heating up a lot. In fact, with the wafer positioned approximately 15 cm from the source, just the radiation from the filament is enough to heat up the sample to 100 C. Then milling the wafer for a minute heats it up to over 260C! These measurements were made by heat sensitive stickers placed on the back side of the wafer.

These temperatures are still too hot because most resists would melt or reflow. In an attempt to reduce wafer heating, the beam current is reduced from the default value of 120 mA. At 1/2 the beam current, the wafer backside temperature reached 210 C. At 1/4 the beam current, the temperature reached 180 C. These temperatures are still too high to process resist. Specifically for AZ1512, high temperatures causes bubbles to form in the resist.

Further reduction in wafer heating is achieved by moving the sample further away from the ion source. At 30 cm, the wafer temperature from the filament radiation alone is under 80 C, the lower limit of the temperature sticker. Then 1 minute of milling at a beam current of 120 mA heats up the wafer to 110 C, a significant reduction. However, this is still not low enough since bubbles were still forming in AZ1512.

Ultimately, the beam needed to be cycled on and off to keep the surface temperature of the wafer low enough. The On cycle mills and heats up the wafer. The Off cycle allows time for the heat to dissipate to the wafer holder.

The experiments were performed by Mohammad K. His efforts reveal a clear direction towards upgrading the ion mill system. For now, to keep your wafer/sample from overheating do the following:
1) Place your sample far from the source
2) Use a lower current setting
3) Cycle the beam on and off

11/26/2014

We recently upgraded our ion milling system by replacing its 3 cm RF ion source with a new 7.5 cm DC ion source. The installation took and entire day to install and another half day to characterize. The new ion source was selected to produce a uniform mill across a 3" wafer and it delivered. Veterans users of the system will appreciate the stability, reliability and ease of use.

03/21/2014

We've just rolled out the new Nanofab Inventory. It's a custom database we created that you use to record items you are storing in the Nanofab cleanroom. When you enter an item the thermal printer will create an official ID label. Items with the official label are officially owned by you. Others can look up the item in the database using the bar-code scanner or by simply typing in the ID number to find your contact information. Now there will be an easy path for anyone who wants to use your stuff to look you up in the database and contact you to get permission.

The Nanofab Inventory will also serve as a chemical inventory. Users who store chemicals will attach a PDF of the Materials Safety Data Sheet directly to the entry in the database. That way you can quickly find out safety information about other people's chemicals that you might encounter in the cleanroom.

11/20/2013

Students from Spring High School visited the University of Houston on a tour arranged by the UH ASME Student Chapter (https://www.facebook.com/UnivHoustonASME?ref=ts). One of the tour stops was at the Nanofabrication Facility. Most of these students are interested in going to college to study science and engineering and they already know how to make the cougar sign!

09/17/2013

We are promoting pole tip awareness. If you use our FIB or SEM, please take some time to consider that even a small ding to the pole tip could render it unusable and the cost to replace it is probably more money than you made last year! Make sure there is plenty of clearance between he pole tip and the stage before you shut the chamber door. Follow procedures when you are bringing the sample to the working distance. If you have tall or unusually shaped samples, think things through before you move or tilt the stage.

08/30/2013

Nanotechnology researchers at the University of Houston will soon be able to work faster than ever thanks to a grant from the National Science Foundation (NSF).

06/20/2013

http://youtu.be/DOCIb-rssQk

Undergrads discuss why they chose the University of Houston Cullen College of Engineering: unique research opportunities, fun and dynamic campus life, connec...

06/17/2013

The UH Nanofab cleanroom was one of the sites selected for the Cullen College of Engineering's student recruitment video, here are some behind the scenes photos from the shoot.