1. IISME Fellowship Description

2. I worked at Stanford University in a chemical engineering lab.

3. Stanford likes its creepy statues.

4. 2013
Last summer the new chemical engineering building was under construction

5. 2014
This summer we moved into the new building

6. What does a chemical engineering lab look like?

7. Complex equipment had to be completely disassembled, packed, moved, and reassembled. This is an ALD reactor. More about ALD later.

8. This is another ALD reactor.

9. This is an MLD reactor.

11. This is a glove box. This is how you work with chemicals you don’t want to expose to air.

12. Much of the research done in the Bent lab can be applied to electronics.

13. Goal: deposit ZnO ONLY on SiPt
ZnO

14. Hypothesis: SAMs will block ALD
Dielectric
Metal
SAM
deposition
ALD
Dielectric film
SAM = self-assembled monolayer
ALD = atomic layer deposition
Self-assembled monolayers (SAMs) bond to metals but not silicon. They prevent the atomic layer deposition (ALD) precursors from reaching the metal surface.

15. Atomic Layer Deposition (ALD)
Zn(C2H5O)2 + H2O → ZnO + 2C2H5OH
ALD creates thin films of uniform thickness. The surface is exposed to one reactant at a time for as many cycles as needed (more cycles = thicker film).

16. Procedure
1) Immerse substrates in SAM solution Si Pt

17. Procedure
2) SAMs form on metallic surface Si Pt

18. Procedure
3) ZnO deposited by ALD Si Pt
ZnO

19. What does this look like IRL?
Start with a wafer...

21. Pt
wafers are cut into small substrates

22. Si Cu

23. Sonicator
substrates are sonicated in ethanol for 10 minutes, then in acetone for 10 minutes

24. Sonicator Sound energy is used to loosen particles from
substrate surface

25. UV Ozone generator UV light source
Substrates are dried with nitrogen, then placed in the UV ozone generator to further clean the surface. One set of substrates were cleaned with sonication only, and the other set with sonication AND UV ozone.
UV Ozone generator

26. O3 decontaminates the substrate surface
UV Ozone generator

27. substrates are now placed in vials with SAM solution
0.1mM
1mM
10mM

28. the vials are sealed with parafilm and placed in a water bath at 30oC for various times (2hr, 4hr, 8hr, 18hr, 24hr)

29. When the predetermined time is up, substrates are rinsed with ethanol and dried with nitrogen, then placed in sample cases. It’s important to label everything very clearly.

30. ...because sometimes you have a lot of samples to test!

31. Ellipsometer measures thickness
First, the samples are taken to the ellipsometer. The ellipsometer uses polarized light to determine how thick a sample is.
measures thickness

32. Goniometer
measures water contact angle

35. Si Pt low water contact angle hydrophilic surface
SAMs not likely present
high water contact angle
hydrophobic surface
SAMs likely to be present

36. syringe needle
water Pt
glass slide

37. syringe needle
water Si
glass slide

38. XPS samples go inside here
Samples are taken to the XPS (x-ray photoelectron spectroscopy) chamber in a different building.

39. XPS
samples

40. A beam of x-rays bombards the sample, causing electrons to move to an excited state. When they return to their ground state, photons are emitted and detected. The energy given off is used to identify elemental composition.