Mag-SPICE

 

Motivation

Today, the emergence of the hybrid magnetic/CMOS devices, like the MRAMs, is a real fact. In this new kind of circuits, the physics of the semiconductors joins the magnetism, giving rise to a complex system. To design highly optimized and accurate devices, obviously this bivalent character has to be taken in account. Up today, there are no TCAD tools (fig. 1) devoted to design hybrid magnetic/CMOS devices.

Solution

From architectural point of view, these new devices involve two lengths scale (fig. 2): one macroscopic related to the addressing lines and one nanometric associated to the magnetic elementary cell. In fact, a coherent description of the magnetic element has to be done by using a micromagnetic dynamic approach since the MRAM works at GHz and the exchange interaction is fundamental. The rest of the environment (CMOS, addressing lines,..) has to be treated by a macroscopic model. Thus, by combing micromagnetic simulation and a macroscopic treatment, a realistic description of the magnetic cell coupled to its environment is expected.

Several points will be addressed by the project :

  1. the phenomenological description of the isolated magnetic cell (dynamic behavior, including the effects of the temperature and the spin polarized current,...)
  2. the behavior model of the magnetic cell connected to its environment (using a macro-micro coupling technique)
  3. integration of the magneto-restive information derived from (a-b) in a memory compiler

Aims

Development of a simulator (Mag-SPICE) specific for magnetic elements integrated in hybrid magnetic/CMOS devices.

Team

-  Liliana Buda-Prejbeanu
-  Fabrice Bernard-Granger
-  Virgile Javerliac
-  Jean-Pierre Nozières
-  Jean-Christophe Toussaint

Collaboration with TIMA (Grenoble)
-  Kholdoun Torki
-  Florin Ciontu
-  Bernard Coutois

Main publications

-  L. D. Buda, I. L. Prejbeanu, U. Ebels, K. Ounadjela, Micromagnetic simulations of magnetization in circular cobalt dots, Computational Material Science 24 (1-2), 181-185 (2002)

-  I. Firastrau, L. D. Buda, J.-Ch. Toussaint, J.-P. Nozières, Boundary Element Method and Micromagnetism coupling for magnetoresistive heads modeling, to be published in J. Magn. Magn. Mat.

Industriel partners

-  Cadence
-  Crocus


Fig. 1
Conception flow of circuits based on semiconductors.

Fig. 2
MRAM-FIMS elementary cell. (a) Writing and (b) reading protocol.