MESA+ University of Twente
Research Business & Innovation About MESA+ Storyline Education

Gratiela Isai (promotion date: 26 May 2003)

ECR Plasma Deposited SiO2 and Si3N4 a room temperature technology


Promotion date: 26 May 2003

Gratiela Isai

I have worked in the group of semiconductor components, mostly in the labs of MESA+: the clean room and testing room. I deposited thin films for thin film transistors, which are the transistors used in laptops and flat panel displays. My purpose was to deposit these films at room temperature. Usually when you want to obtain a high quality dielectric you need a furnace at approx. 1000 degrees. But if you want to make transistors on glass or plastic this method obviously is no option.

Could you tell us something about your research?
I have worked in the group of semiconductor components, mostly in the labs of MESA+: the clean room and testing room. I deposited thin films for thin film transistors, which are the transistors used in laptops and flat panel displays. My purpose was to deposit these films at room temperature. Usually when you want to obtain a high quality dielectric you need a furnace at approx. 1000 degrees. But if you want to make transistors on glass or plastic this method obviously is no option.

I used ECR plasma, in order to obtain dielectrics at low temperature comparable with the ones grown at a temperature of 1000 degrees. I optimized the deposition equipment, but apart from that I characterized the films, measuring their roughness, composition, etc. The practical outcome is a step forward towards more complex three dimensional circuits and towards the fabrication of transistors on all kind of surfaces. My study took half a year longer due to the very experimental side of my research and also due to the 4 months maternity leave. I had a baby girl.

So your study had a considerable practical side to it?

Yes, I spent quite some time in the clean room, making the film and making the devices.

In the testing room I measured the electrical properties.

Do you prefer the practical side?

I like the combination between the experimental and the theoretical work. You have the variety, which for me is very important. Also the experiments take your theory further.

Did you work as a group?

In a PhD project you work independently to a large extent. Of course you have contact with your supervisor weekly, but you are also put to the test to see if you can work independently, without daily instructions.

Did you take other training during your studies?

I did courses in IC technology, because I finished solid state physics in the university and then working in electrical engineering was a bit difficult. The courses were very useful for my clean room work. I took other courses such as how to plan you work, how to present papers and write them, and how to work with master students.

Some courses I found more interesting than others. Teaching in higher education was very interesting. I come from a different educational system. In Romania the teacher presents the problem at the whiteboard and the students may or may not pay attention. Here the students, in groups or independently, have to solve the problem themselves. The teacher helps them by giving them hints only when they are stuck. I think that the students learn more in this manner.

How did you get to study here in Twente?

Mr Cobianu, director of the thin film lab at a research institute in Romania had contacts with Twente. First I wanted to go to the USA, but he pointed out to me that the University of Twente is a very good place for research.

What are your plans for the future?

I would like to continue to work at the university as a postdoc; in an educational department maybe.

Do you regret not continuing your project?

No, during the 4 years of your research you realize that you could not possibly do all you would like to do. At the beginning of the fourth year you must choose what you can do in the limited time left. This is the moment when you experience some regrets. But after finishing the 4 years, you feel the need to move on and try something else.

Is it not a problem working full time and being a mother?

That is a typical Dutch question. In Romania women can stay the first two years at home with 85% of their salary, and after that most of them go back to work full time. But there of course you have grandparents at hand who look after the children.

I think my daughter will have a happier mother when I am working and I am sure she will enjoy her time in the day care.

What did you like most about your studies here?

I liked the fact that I had the possibility to “see” what I am doing. This occurs when you do experimental work.

What was the most difficult?

The routine of cleaning silicon wavers was not a job I particularly enjoyed. But the most difficult is probably the moment which I think every PhD student has at a given point in time: the momentarily despair of thinking that it is not going to work. In my view the best thing to do then, is go and talk to someone. In my case it helped.

For the summary of the thesis, click here. (English)