The Extraction Of Dielectric Functions Using an Ex-Situ Spectroscopic Ellipsometry Multisample Analysis Approach

Jennifer Rittenhouse Author

07/28/2021 Added

61 Plays

Description

After Fabricating 22 nanoscale thin films divided between two techniques, optical constants were extracted in this study.

Searchable Transcript

Search:

[00:00:01.890]Hello, my name is Jennifer Rittenhouse,
[00:00:04.150]and I'm a Physics Major attending Millersville University.
[00:00:07.620]In this presentation, I will be discussing the extraction
[00:00:10.390]of Dielectric Functions using an Ex-situ
[00:00:12.750]Spectroscopic Ellipsometry Multi-sample Analysis Approach.
[00:00:17.820]The means of how a material is deposited
[00:00:20.070]when fabricating a thin film
[00:00:21.730]can drastically alter its optical properties.
[00:00:24.740]Deposition conditions and techniques alter how light
[00:00:28.180]and energy interact with those material
[00:00:31.560]that's being described by its optical constants
[00:00:34.010]and bioelectric function, respectively.
[00:00:36.830]By understanding and exploiting these method,
[00:00:39.460]we can enhance the materials of our technologies
[00:00:42.210]to make up our everyday life from optical switches,
[00:00:45.460]chemical gas sensors, electrochromic smart windows,
[00:00:48.810]and improve solar panels, to name a few examples.
[00:00:55.080]Using two separate deposition techniques,
[00:00:57.390]we fabricated 22 individuals thin films
[00:01:00.380]divided between two separate experiments.
[00:01:03.010]The thin films were measured
[00:01:04.300]with the spectroscopic ellipsometer
[00:01:06.490]in order to perform a multisample analysis.
[00:01:09.520]The analysis was fitted to a model
[00:01:11.790]and these optical constants
[00:01:13.390]were compared with prior research literature.
[00:01:17.660]For the first sample set,
[00:01:18.880]we deposited Polymethyl methacrylate (PMMA),
[00:01:22.190]onto silicon wafers using a deposition technique
[00:01:25.290]called sol-gel spin coating.
[00:01:27.420]Sol-gel spin coating is a deposition method,
[00:01:29.920]where a centrifugal force spreads the material uniformly
[00:01:33.350]across the substrate.
[00:01:35.080]In our study, we pipetted four sets of PMMA solutions
[00:01:38.770]with different density, and changed their rotation speed
[00:01:42.560]in increments of 500 RPMs per sample.
[00:01:49.580]For the second sample set, we used a magnetron sputterer.
[00:01:53.193]A nanofabrication device,
[00:01:54.790]where an ionized gas in a pressurized vacuumed chamber,
[00:01:59.530]collides with negatively charged target material,
[00:02:03.470]and then, sputters off onto a rotating substrate.
[00:02:11.340]After collecting our samples, we measured our initial data
[00:02:14.450]with the spectroscopic ellipsometer.
[00:02:17.040]Spectroscopic ellipsometry or SE,
[00:02:19.670]utilizes changes in polarized light
[00:02:21.860]as it reflects off of sample,
[00:02:23.810]which in turn measures its thicknesses
[00:02:26.380]and optical constants.
[00:02:32.660]Multi Sample Analysis, as the names suggests,
[00:02:35.280]uses multiple samples, analyzing them simultaneously.
[00:02:39.850]This approach allows one
[00:02:41.390]to determine the thicknesses of samples
[00:02:43.240]which might be difficult to normally resolve
[00:02:45.810]because of how thin they are.
[00:02:47.930]It is important to note that the samples must be
[00:02:50.340]of different thicknesses, and that one can assume
[00:02:53.040]that same dielectric function
[00:02:54.650]for all the samples.
[00:02:57.440]Upon analysis and systematic study of different model,
[00:03:00.960]it was determined that the sample sets of PMMA,
[00:03:03.940]most closely matched a Cauchy relation model.
[00:03:07.080]We compared four different optical constant plots
[00:03:10.050]with different densities
[00:03:11.300]to that of available literature PMMA,
[00:03:14.070]and found that 1.5 milligrams per milliliter density,
[00:03:17.590]PMMA solution was comparable to the literature,
[00:03:20.270]as shown in this graph.
[00:03:23.580]Further analysis showed a relationship
[00:03:25.750]between density and rotations per minute,
[00:03:28.360]and the thickness of film in nanometer.
[00:03:30.890]Atomic Force Microscopy was also performed
[00:03:33.330]to examine the morphology of the sample.
[00:03:39.730]Silicon Dioxide Film with varying deposition times
[00:03:42.460]were measured with ellipsometry,
[00:03:44.260]and their optical constants were successfully modeled.
[00:03:47.090]Scanning electron microscope images
[00:03:48.930]were also taken to examine surface
[00:03:50.840]and roughness features.
[00:03:53.100]The optical constants were also measured
[00:03:55.090]for measuring the ellipsometric data
[00:03:56.840]from silicon on top of silicon substrates.
[00:04:01.030]In conclusion, we successfully fabricated PMMA thin films
[00:04:05.160]using sol-gel spin-coating technique.
[00:04:07.900]Using a magnetron sputterer device,
[00:04:10.370]we fabricated thin films
[00:04:12.070]of silicon dioxide and silicon, respectively.
[00:04:15.570]As a systematic case study,
[00:04:17.510]we performed PMMA thin-film depositions
[00:04:20.120]of different densities
[00:04:21.170]and extracted their optical constants.
[00:04:24.150]We found that the change in density
[00:04:25.770]results in the change of refractive index
[00:04:28.090]as well as the thickness of PMMA thin films
[00:04:30.300]for the same rotation speed.
[00:04:32.400]By using spectroscopic ellipsometry data based
[00:04:35.030]multisample analysis, we achieved the extraction
[00:04:37.930]of optical constants together with thin film thicknesses.
[00:04:41.980]Using scanning electron microscopy
[00:04:44.220]and atomic force microscopy techniques,
[00:04:46.470]we investigated the morphology
[00:04:48.100]of fabricated thin films.
[00:04:52.250]I would like to pay special acknowledgement
[00:04:54.720]to the Schubert laboratory team,
[00:04:57.220]who I worked alongside this summer
[00:04:59.010]at UNL Research Laboratories,
[00:05:01.420]with special emphasis on ‪Ufuk Kilic,
[00:05:04.440]who helped me to be able to understand
[00:05:06.900]and operate the various machines that we use
[00:05:09.280]for the fabrication techniques.
[00:05:13.890]This is my poster.
[00:05:15.150]I would also like to acknowledge, Dr. Adnan Adawi,
[00:05:17.690]as well as Dr. Beilin Ma,
[00:05:19.420]who wrote letters of recommendation,
[00:05:21.250]as well as the National Science Foundation
[00:05:23.300]for which I would not be here otherwise.
[00:05:25.695]Thank you for your attention.

The screen size you are trying to search captions on is too small!

You can always jump over to MediaHub and check it out there.

Comments

0 Comments

The Extraction Of Dielectric Functions Using an Ex-Situ Spectroscopic Ellipsometry Multisample Analysis Approach

Description

Searchable Transcript

Comments icon comment

Related Channels

Comments