How is it possible to improve memory chips?

Improvements in memory chips are now only possible by bringing in new materials that

can be laid down with the high quality needed. And the advances that we have made in

the REALISE project are going to allow more data capacity in flash memories and

faster transistor operation.

Which are these new materials?

The new materials are rare earth oxides: a fine powder that functions as an

electronic insulator. It will isolate the electrical information on computer chips.

The material itself is not costly and also the amounts used for nano thin layers are

tiny. Of all the elements in the periodic table the rare earth elements were

discovered relatively late. They were in the same mineral deposit and so they were

all classified together. We now know that they are not all that rare and that they

are useful elements for a variety of purposes. Like other metals they form oxides.

The rare earth oxides are safe and inert and they have useful electrical

characteristics. For those reasons they were aimed to be used in this project

because they behave as very good insulators.

How are these materials integrated into the memory chips?

The crucial element of the REALISE project is how to bring these oxides down onto

the chips and integrate them into the structures that are needed. The process used

is called ALD, atomic layer deposition. As the name implies, the scientists try to

lay down the layers atom by atom at a very fine scale. The chemical process has been

developed since the 1970ies and has now been used in the electronics industry to

make transistor chips. Another advantage: ALD can coat complicated three-dimensional

structures at the nano scale. Using the REALISE materials in 3D structures for

capacitors means that each capacitor uses less surface area on the wafer, leading to

an associated saving of 70 percent in cost. The project partners are sure that the

huge benefits these new materials will bring for the electronics industry will more

than outweigh the costs. Therefore, the aim is to produce a highly-insulating

dielectric material, with a so called high k-value, which enables a large

capacitance in memory chips.

Which is the role of nanotechnology in this project?

The electronics industry is probably the main example where we use nano technology

every day in our daily lives. All electronic components are now down on the nano

meter scale. And the new films that are needed for memory chips now must be as thin

as two or three nano meters. It is very hard to manufacture films that are this thin

with the high quality and the high uniformity that's needed. So that is what the

REALISE project was aiming to achieve, to lay down these with that nano meter scale

quality.

Have you already performed some tests?

Our institute was responsible for simulation of the deposition process and for

testing rare earth oxide material properties. To measure the capacitance that is

gained with the new process, probe tips contact one of the chips on the processed

wafer to apply a voltage across the rare earth films on it. The electrical tests

determined that the new material performs in terms of its insulating properties

three times better than alumina, the previous best material. Devices could therefore

be made that are three times smaller than the current record, with the bonus of

double the working lifetime. The REALISE project has developed a technology that is

now ready for industry application. It is the basis for manufacturing a one terabyte

USB stick in the near future.