Hi

I think the thickness of your substrate compared to the Ar gas pressure is low.

suggestions,

1- Check tempreture: because it may cause troubles.

2- Change your substrate to thicker one. If you dont have access to thicker and need conductors, you may use quartz+ spraying process of some conductors. ( if you need more detail, dont hesitate to contact me)

3- Change your pressure if it is capable.

A small part of your film (NiTi) is mortally lost[1] in the substrate and the rest part of the film breaks, or even, a smaller part of it was, already, broken[1], before the HNO3 treatment.

I propose to add a new NiTi (3rd) film in order to get a better quality of a free standing NiTi from your system.

In details, this proposal consist of the following 3 layers on Si wafer:

1. Start with a buffer layer film (Ti, or NiTi),

2. add a thick[2] Cu (2rd) film

3. add a new NiTi (3rd) film, having better quality, than your older NiTi (2nd) film.

1. Sacrificial adhesion promotion layers for copper metallization of device structures

Article Sacrificial Adhesion Promotion Layers for Copper Metallizati...

2. https://www.researchgate.net/post/How_to_deposit_thick_layer_of_Cu_on_Si

Elham Easy The temperature seems good. I will try reducing the pressure. If that doesn't work I will get back to you about the spraying process.

Thanks

Phuong V. Pham

Ioannis Samaras Thanks for the suggestion. I will look into it and get back to you

Dear Sir,

The pressure is indeed far too high, by which you get very high thin film stress. By the way, if you use DC magnetron sputtering (with a decent magnetron/magnet array yielding high magnetic stray fields), then your deposition pressure should be in the 2-5E-03 mbar range: 3 orders of magnitude lower than what you use. For RF the pressure is much higher of course.

To obtain free standing films, a good trick is to use the same substrate, but dip it before mounting in the chamber in a strong, i.e. high concentration , solution of sugar (yes, normal glucose). The sugar will, after drying, form a film of glucose on which the adhesion on the deposited thin film is very bad: you will basically be able to release the thin film by bending the substrate. If it doesn't work with your substrate, try a substrate of PET (100 µm in thickness or less).

Success!

Paul Lippens Thanks for the suggestion. I have already tried despositing at 2.0E-03 mbar with 500w and the result was too bad. I have attached microscopic images which were taken after 2hours of deposition for your reference.