Roberto Gauna, 2021 NIST Research Intern

Biography

SPS Chapter: Massachusetts Institute of Technology

My name is Rob and I am from a small city called Pharr along the southern border of Texas.
My interests generally lie at the intersection of digital systems/controls design, and physics experimentation.
I am currently finishing up my EECS & Physics degrees at MIT, and hoping to start my Master’s of Engineering in Applied Physics in the Fall.
I am an avid percussionist (Jazz & Orchestra), cook, traveler, and more recently a gym rat.

Internship

Host: National Institute of Standards and Technology (NIST)

Project

Abstract

Scanning Kelvin Force Microscopy (SKFM) is a form of noncontact atomic force microscopy (nc-AFM), more specifically an electrostatic force microscopy (EFM) technique, which makes use of the electrostatic forces between the cantilever probe tip and the sample to image and characterize the sample properties at subnanometer scales. Because electrostatic forces occur over long distances SKFM/EFM can be used to characterize subsurface structures, making it useful for imaging/testing 3D integrated circuits. SKFM/EFM is used today for measuring circuit properties such as dielectri constant, accumulated charges, and conductivity variations. I will present on my remote bias EFM simulations which focused on characterizing subsurface aluminum stripsembedded in Silicon Dioxide (SiO2) and Hafnium substrates with varying probe tip geometries.

Final Presentation

Internship Blog

Week 1 - A soft introduction to AFM and CoC (Blockchain on Supply Chain)

A bit late to the party, but here goes

Started the internship off with a rocky start. I had to move out of my apartment the same day the internship started, then had to make a 1,400 mile trek from South Texas to South Florida. But luckily my supervisor is super understanding.

The other intern (Karthik) and I started the week with a soft introduction to “Atomic Force Microscopy” given by Joe, our NIST supervisor. Joe went over KPFM (Kelvin Probe Force Microscopy), a specialized type of AFM, and what we will be investigating using COMSOL. Hopefully will get to see more of this in the coming weeks.

In addition to this project Karthik and I are planning to investigate how we can use electronic fingerprinting for supply chain securing. We have to look into current research on how blockchain technology is being implemented in current supply chain actors. So far Dr. Yaw Obeng is leading this project and just wants us to propose possible schemes based off of current research. I think there is also the question of what exactly we want to use to fingerprint on the microchips.

As of today (June 8th) I have very little to report. I am setting up my computers and all the software it looks like I will need for the summer. I have my RSA token (issued by NIST) but have no idea how to access the remote service. Hopefully everything will be setup by tonight and I will have substantial progress by the end of the week.

Week 2 - Settling in, Remote work, and the Beach

My last post was a bit rushed and late; I hope this post will be more substantial.

I started off the week in New Orleans. Little sleep the 2 nights before and another 12 hours of driving ahead of me.

I climbed into my car with my friend and my cat and we hit the road.

The drive went without a hitch, minus the torrential rain that blinded all the drivers for about 10 minutes.

Thinking back at that 12+ hour drive makes me exhausted so I will leave much of the details out.

Productivity at work has been at a crawl all week.

We (Karthik and I) are supposed to be investigating some scanning probe properties on COMSOL but are currently still working out things with IT to get us setup.

So far the supervisors (Joe and Yaw) have given us some soft ball work, modeling some microinterface as a lumped circuit model with the goal of finding a circuit model that exhibits some changes in resonant frequency with changes in resistivity.

So far no luck as expected but Joe said that he’ll suggest some circuit models to try.

Besides some mock lumped circuit modeling I tried to install COMSOL onto my local machine but keep running into some licensing trouble ...

IT and Joe mentioned I will need to create an account on my Windows machine that matches my NIST account; but which one? It seems my NIST email doesn’t work sooo might try my other username

I am also in the works to get a keyfile for remote working into either Joe or Yaw’s workstation.

I think if I wait for the keyfile I won’t hear back from IT until later next week so I think I am going to go the route of installing COMSOL on my local machine

Not sure how much else I need to complete. I think it might be worth summarizing what I have been reading for the supply chain project.

Besides work stuff, here in Florida it has been HOT and sunny

My fiance and I often go to the beach and enjoy being reunited after a few months apart

Her family spoils me with Cuban food and treats

I’ve watched a lot of the susets

My goal for this summer is to play with a live band at a bar; I’m an avid percussionist and would love to play congas for a Salsa band..

Or maybe just play my drums a little more this summer.

I missed a few SPS meeting this week because I was still unpacking and playing catch up with my responsibilities

This coming week I should be back on the ball and attending all meetings

More to come over the weekend!

Week 3 - LTSpice, COMSOL, X-country trip II

So I keep uploading this same picture for my headshot because the machine I am on doesn’t have any of my photos ..

Week 3 started out a bit slow. I was tasked with trying to find a lumped circuit model that has a significant dependence of resonant frequency on resistivity properties.

Some preliminary google searching and just knowledge of circuits tell me that resistivity affects the quality of the resonant peak; nonetheless I still had to investigate some circuit schemes. Nothing from the simulations seemed to contradict this claim so it seems that this project will not lead anywhere.

It does seem that one of my supervisors has a better idea of circuit schemes that we should investigate but I think we were just waiting to model some of the actual devices in COMSOL instead of lumped circuit models. I think the scope of this project is narrowing down and we will have a better idea of what to investigate when we get COMSOL working.

As the week progressed I also was attempting to get COMSOL installed on my local machine under one of NIST’s licenses.. took a while but I was successful and I am now running simulations (very large and slow) on my local machine! Next step is to investigate the geometries of the tips as well as the test structures that we are supposed to be scanning. In the next week I should be verifying my simulations with lab results that Joe (supervisor) is getting in the lab.

Not related to work:

All the while I am enjoying my time in Florida before my return to Boston

I had a friend visiting me that left on Wednesday; unfortunately did not get to take them mango picking or kayaking :(

By the way if you happen to find yourself in South Florida during the early summer (May/June) one thing I would recommend is picking mangoes!! They are in full bloom and can easily be found in residential areas.. just don’t get caught on somebody’s lawn!

My fiance has been taking me out almost every day to see her family and while I am enjoying catching up and all the free food that comes with the visits I was relieved when we decided to stay in this weekend.

Now that I had some proper rest I am ready to face week 4 of this internship and hopefully get some results that are actually presentable

Oh! I also signed for my new apartment in Boston (Quincy). It’s a corner unit with a patio out to some woody area; I’m hopeing my cat will enjoy the view :) ..

I am definitely looking forward to being back in the Northeast, but I am not looking forward to another 1500+ mile drive ..

C’est le vie

This time I will be making several stops in Atlanta, Richmond, and Philly! Always open to recommendations!

Anyway this blog post is a bit of a mess, but so is life sometimes ..

Logging off and hopefully will be posting some results from the COMSOL simulations this coming week!

Week 4 - Too many plans and COMSOL

My girlfriend loves making plans.

Before the end of last semester she had plans for 2 surgeries, a birthday party, a graduation party, a new apartment for the summer, a new apartment for the fall, trips to Naples, Key West, Titusville .. and so on

This past week we spent a bunch of time making plans for the remainder of our stay in Florida, arrangements for our drive to Boston, then rearrangements for the drive because we ended up inviting her family to make the drive with us.

I enjoy being involved but it sure is an energy drain.

As for my internship

I think I am getting the hang of how COMSOL works. Not entirely sure about all the bells and whistles that come with the physics modules, but I am getting the hang of running the studies and extracting the data.

Most of the past week was just spent building the new models that we need to scan, as well as running some simple sweeps across a test strip. I started running simulations for measuring the potential of a subsurface aluminum strip embedded in a silicon substrate, and I think I am getting the hang of running the parametric sweeps but they take quite long for just 20 data points.. I am wondering how long the larger parametric spaces are going to take to run

This weekend I am suppossed to run the parametric sweep for a multistrip setup but Joe also mentioned that he’d send over a new design for the probe tip so I am not sure if I should still run the study or if I should wait for the new probe shape.. I think I’ll wait until Monday before I run the simulation.

Other than that I think the other intern (Karthik) finally got access to COMSOL so it is looking like we’ll be working full throttle soon!

Next week I should begin uploading images my results for viewing pleasure!

Week 5 - Anniversary blackjack and a lazy weekend

This past week was uneventful in both the internship and my personal life.

My girlfriend and I stayed home most of the week and cooked.

It wasn’t until Thursday, our anniversary of 4 years, that we decided to get out.

I had been wanting to go to the casinos for a while, but haven’t had the time (nor the money).

So finally we decided that we would go try our luck at the Hollywood Hard Rock, mostly because it’s free to park and walk .. but also because its a gorgeous building.

We got there and wandered around for about an hour amazed by the beautiful structure and the hoards of people losing their money.

I have gone to a couple of casinos before but the rules at this one were a bit different (i.e. cash only, always need a card to play even if at a table ..., children are allowed in? )

My girlfriend doesn’t like gambling, but she does have a soft spot for blackjack since there is some structure to the game.

So wandering around we find a blackjack table to sit at the dealer tells us that the buy-in is $75 a hand ... so we immediately leave and find a nice comfortable $25 a hand table.

After struggling to converse with the dealer over the sound of the casino games and patrons we buy in and place down $25 each.

I immediately blackjack and the dealer busts; we’re up $55. We go for a 2nd hand; the dealer and I push and my girlfriend wins another round. Now we’re up $75 and we both instinctively decide it’s time to cash out. When you’re up, you’re up. Now we have dinner and gas money

The rest of the week was pretty mild. Her brother came to stay with us for the weekend and we watched some Hulu.

We went to her uncle’s apartment and enjoyed the pool and some BBQ for the holiday.

We hosted her mom and grandmother for the firework show.

And I taught her mom how to play Texas Hold’em

Like I said pretty uneventful.

This upcoming week I will have more to post about the internship

Hopefully some interesting graphs on what we are investigating

But for now, happy July!

- Rob Lobsta

Week 6 - COMSOL, Kava, and Kratum

The past few weeks I have been inverstigating how well an AFM probe can image metallic strips embedded in substrate materials

This sort of measurement is of interest to manufacturers who are now beginning to explore 3D integrated chips

Now that we have reached a limit of how small we can get transistors, 3D integration is a natural direction to explore.

However metal embedded inside substrate isn’t the easiest to probe and test

This project’s goals has been to see how well we can image and distinguish between substrate embedded metallic strips

After several weeks of just getting setup I finall have some presentable results

Now my days are filled with me making small adjustments to my models, running them for hours, and coming back to my laptop every 2 hours to make sure my remote connection doesn’t close..

As much as I want to upload some results, I recently found out that my results are inaccurate sooo I’d like to find the source of this error before uploading anything for the world to judge

Outside of work I of course went to the beach a bunch and tracked a bunch of sand back to my place and my car

I also went to a cool warehouse looking place called Kamp Kava, where I enjoyed some Kava and Kratum

For those that are not familiar (I am no expert myself) Kava annd Kratum are plants that have some pretty mild relaxation properties

The consumption of these plants has been growing in popularity in recent years, since they provide an alternative to other drugs (alcohol and for some reason opiods are cited a lot?)

In my very limited experience I have found that both plants are typically (somehow) served as drinks.

Kratum leaves are crushed up into a powder and disolved into some solvent; in my case they served it with some gatorade and ginger, and another drink was like a banana cream pie. Not bad. Would recommend.

Kratum leaves come in 3 types: Green, White, and some other color I can’t remember. Each has it’s own supposed property (energy, relaxation, ?). I could definitely feel a bit of a pep in my step after my kratum drinks, but not as much as I would with a coffee. So overall a good experience

Kava on the other hand is another plant, which through a similar process is made into a drink. However, Kava tastes like dirt and I haven’t seen anybody try to mask the flavor for some reason. I haven’t exactly tried a lot of Kava, but both times the drink tasted like dirt and made me nauseous .. would not recommend if you find yourself at a place that make kava drinks. I’ve heard of similar experiences where Kava made people sick, but I also wated some down like 8 cups of it when I could barely stomach 1. I guess everyone has their own level of tolerance to dirt flavor ..

Until next week

-Rob

Week 7 - Jazz and graduation

Do you like jazz?

I do. It’s been a few years since I’ve performed with a jazz band, but I think I am ready to get back into it.

The jazz band at my school released this year’s audition piece; we’re playing Down A Rabbit Hole by the Ayn Inserto band. I’m so nervous .. It’s been so long and I was never the best set player to begin with but I have such a strong compelling feeling to try anyway. I have about 40 days to prepare this piece as of this writing and I’ve managed to learn the intro and the first section. I definitely have a long way to go but I believe in myself (kinda), and I think my urge to play is gonna keep me going.

This past week was pretty productive. I managed to generate several analysis studies on the single subsurface strip, and managed to collect all the data I needed for the double strip experiment.

However, it later occured to me that I had made a mistake when generating the probe.

A few weeks ago Joe told us that we were to study 3 different geometries for the probe tip: a symmetric (triangle), a leading edged, and a trailing edged tip. While I managed to figure out how to generate such tips in COMSOL, I completely ignored the specification regarding how thin the cantilever could get. When generating the tip shape, I ignored this aspect of the geometry and am now realizing that the cantilever thickness is on the order of 50nm, when it is actually supposed to be on the order of 3um .. so about 2 orders of magnitude off.

Luckily Joe said the cantilever thickness is most likely only going to have an effect to 3 or 4th order so those won’t contribute very strongly. But I do have to go back and fix the model for a future run of the simulation.

Besides that, I was supposed to run and collect all the multi-strip experiment data over the weekend, but for some reason the simulation kept stopping with an error, so I decided to take the weekend for myself.

Besides work (and jazz) this past week was my girlfriend’s graduation party and we had some of her friends fly in (Seattle and Boston) to celebrate with us. They first arrived on Thursday and that was when my inner hostess kicked in. Luckily we had some extra space for them to stay, but this weekend was definitely on the overcrowded side.

Sunday was the actual party and we were busy from dawn until way beyond dusk. Luckily we had some help with setup, but we were busy picking up some last minute party things up until the party started. We officially told people to start coming around 2pm (which a few did) but since we are running on hispanic / Miami time everyone really arrived around 4/5pm, which was fine by us because my girlfriend was preparing stuff well into the party. It was a great event with lots of leftovers which I will be living off of probably until the end of this internship. Maybe I will edit this post with a picture from that night

I’d give more description, but I have some work to do and some slides to prepare.

Until next week

-Rob