Size and Shape Effects in Shrinking Submicron Magnetic Memory and Logic
Document Type Article
Prepared for The Office of Naval Research.
This research program is based on the premise that selective area deposition of large arrays of micron and submicron scale ferromagnetic features is possible. The magnetic characterization of these features, as a function of both size and shape is a major component of this project but the ultimate goal of this program is to make magnetic device(s). In the first year and a half of this program we characterized the chemistry of magnetic feature fabrication and provided clear demonstrations that the fabrication of large arrays of ferromagnetic features is indeed possible.
The dependence of magnetic properties of a small magnetic feature on both its size and shape is of considerable fundamental interest. Several approaches to fabricating such micron and submicron scale metal features have been undertaken by us, including organometallic chemical vapor deposition (OMCVD) "writing" using scanning transmission electron microscopy (STEM), and U.V. photolysis. We have been able to develop the photolysis of organometallic compounds beyond the simple fabrication of magnetic multilayers to deposit micron-scale magnetic patterns on semiconductor substrates. The photo-assisted selective area OMCVD method has advantages not shared by many other techniques. The deposition rate is a few orders of magnitude faster than the STM techniques. The deposition can be performed in ultrahigh vacuum (UHV); thus, with an appropriate choice of source molecules, chemical contamination can be minimized not only within the growing film but at the surface as well. This technique is undertaken at relatively low temperatures so that unusual magnetic multilayers potentially can be fabricated. This method can yield deposition over a large area in a single-step deposition process. Since there is now enough material for an appreciable signal, magnetic properties can be studied by most magnetometry techniques including in-situ measurements, such as magneto-optical Kerr effect. Utilizing a range of masks, diffraction and relatively short wave length light (light in the U.V.), a variety of magnetic features can be directly deposited over a wide range of size and shape.