Method of making amorphous alloys for semiconductor device

#The present invention generally relates to magnetoelectronics, and more particularly to material composition for magnetoelectronics elements.

#Magnetoelectronics, spin electronics, and spintronics are synonymous terms for the use of effects predominantly caused by electron spin. Magnetoelectronics is used in numerous information devices, and provides non-volatile, reliable, radiation resistant, and high-density data storage and retrieval. The numerous magnetoelectronics information devices include, but are not limited to, magnetic random access memory (MRAM), magnetic sensors and read heads for disk drives.

#Typically, a magnetoelectronic device, such as a magnetic memory element, has a structure that includes multiple ferromagnetic layers separated by at least one non-magnetic layer. In a memory element, information is stored as directions of magnetization vectors in the magnetic layers. Magnetization vectors in one magnetic layer, for instance, are magnetically fixed or pinned, while the magnetization direction of the other magnetic layer is free to switch between the same and opposite directions that are called “parallel” and “antiparallel” states, respectively. In response to parallel and antiparallel states, the magnetic memory element represents two different resistances. The resistance has minimum and maximum values when the magnetization vectors of the two magnetic layers point in substantially the same and opposite directions, respectively. Accordingly, a detection of change in resistance allows a device, such as an MRAM device, to provide information stored in the magnetic memory element. The difference between the minimum and maximum resistance values, divided by the minimum resistance is known as the magnetoresistance ratio (MR).

#The present invention will hereinafter be described in conjunction with the appended drawing figures, wherein like numerals denote like elements, and:

#FIG. 1 is a table comparing the various properties of certain alloys suitable for use in MTJ applications, including one specific alloy deemed most suitable according to a preferred exemplary embodiment of the present invention;

#FIG. 2 is a cross-sectional view of a magnetic element with improved magnetic response according to a preferred exemplary embodiment of the present invention; and

#The following detailed description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description of the preferred exemplary embodiments.

#The following characteristics are deemed desirable to provide for smoother layers and enhanced magnetic performance in a magnetoelectronic device: relatively low magnetostriction; relatively high recrystallization temperature (i.e., greater than 300° C.); minimal dispersion (spatial variation) of anisotropy; relatively high stability of anisotropy; a substantially nickel-free (Ni-free) composition to increase the thermal endurance of the MTJ stack; near zero magnetorestriction coefficient (λ), and relatively high polarization for high MR %. While this list of desirable characteristics is not exclusive or exhaustive, it is indicative of some of the more salient characteristics that may be considered when selecting materials for fabricating ferromagnetic layers in magnetoelectronic devices according to the preferred embodiments of the present invention.

#Accordingly, disclosed herein are various amorphous alloys exhibiting, in various combinations, the desired characteristics discussed above. For purposes of discussing the various embodiments of the present invention, the term “amorphous” as used herein shall mean material layers in which there is no long-range crystalline order such as that which would give rise to a readily discernable peak using normal x-ray diffraction measurements.