Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Having insulated electrode
Reexamination Certificate
2002-01-09
2003-02-18
Elms, Richard (Department: 2824)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Having insulated electrode
C257S421000
Reexamination Certificate
active
06521931
ABSTRACT:
FIELD OF THE INVENTION
This invention pertains generally to a method of fabricating an MRAM structure, and more particularly, to an MRAM structure that has the pinned layer recessed within a trench with an upper magnetic layer positioned over it.
BACKGROUND OF THE INVENTION
Integrated circuit designers have always sought the ideal semiconductor memory: a device that is randomly accessible, can be written or read very quickly, is non-volatile, but indefinitely alterable, and consumes little power. Magnetoresistive random access memory (MRAM) technology has been increasingly viewed as offering all these advantages.
A magnetic memory element has a structure that includes magnetic layers separated by a non-magnetic layer. Information can be written and read as a “1” or a “0” as directions of magnetization vectors in these magnetic layers causing resistance variations. Magnetic vectors in one magnetic layer are magnetically fixed or pinned, while the magnetic vectors of the other magnetic layer are not fixed so that the magnetization direction is free to switch. In response to these shifting states, the magnetic memory element represents two different resistances or potentials, which are read by the memory circuit as either a “1” or a “0.” It is the detection of these resistance or potential differences that allows the MRAM to read and write information.
It would be desirable to be able to fabricate higher density MRAM memory devices with increased precision, and with a reduced number of simplified steps. It would be desirable to be able to form one or more integrated MRAM devices so that accurate placement of the top magnetic layer over the bottom pinned magnetic layer can be assured. A self-aligned process would serve this purpose. It would be an advantage if such a process were easily repeatable so as to allow the fabrication of a plurality of layers of MRAM device integration.
SUMMARY OF THE INVENTION
This invention pertains to a method of fabricating an MRAM structure and the resulting structure. The MRAM structure of the invention has the pinned layer recessed within a trench with an upper unpinned magnetic layer positioned over it. The method of fabrication utilizes a spacer placed within an etched insulator opening to reduce the opening size. The upper magnetic layer of the MRAM stack structure is formed within the smaller size region defined by spacers, thereby allowing for accurate placement and self-alignment of the upper magnetic layer over the underlying pinned magnetic layer. This process is repeatable to form multiple MRAM device layers for heightened levels of vertical integration.
These and other feature and advantages of the invention will be more clearly understood from the following detailed description, which is provided with reference to the accompanying drawings.
REFERENCES:
patent: 5569617 (1996-10-01), Veh et al.
patent: 5650958 (1997-07-01), Gallagher et al.
patent: 5732016 (1998-03-01), Chen et al.
patent: 5838608 (1998-11-01), Zhu et al.
patent: 5852574 (1998-12-01), Naji
patent: 5902690 (1999-05-01), Tracy et al.
patent: 5920500 (1999-07-01), Tehrani et al.
patent: 5936882 (1999-08-01), Dunn
patent: 5956267 (1999-09-01), Hurst et al.
patent: 6081445 (2000-06-01), Shi et al.
patent: 6137182 (2000-10-01), Dawson et al.
patent: 6165607 (2000-12-01), Yamanobe et al.
patent: 6313973 (2001-11-01), Fuke et al.
patent: 0 827 195 (1998-03-01), None
patent: WO 00 52701 (2000-09-01), None
MRAMNew Ways to Store More(accessed Jun. 21, 2000) <http://www.hp.com/ghp/features/storage/storage3.html>.
Nonvolatile Electronics, Inc.Magnetoresistive Random Access Memory(MRAM) (accessed Jun. 21, 2000) <http://www.nve.com/otherbiz/mram.html>.
Advanced Technology ProgramMagnetoresistive Technologies Attract a Growing Audience(accessed Jun. 21, 2000) <http://www.nist.gov/public_affairs/factsheet
ve.htm>.
Stuart Parkin, MagRAM,Non-Volatile Magnetic Random Access Memory(accessed Jun. 21, 2000) <http://www.almaden.ibm.com/st/projects/magneto/mram/>.
Science and Technology at Almaden,Magnetoelectronics(accessed Jun. 21, 2000) <http://www.almaden.ibm.com/st/projects/magneto/index.html>.
EDAtoolsCafeMotorola Demonstrates Revolutionary Memory Technology(accessed Jul. 10, 2000) <http://www.dacafe.com/DACafe/NEWS/CorpNews2/20000513_il_motorol_4.html>.
Nanomagnetics(accessed Jul. 10, 2000) <http://itri.loyola.edu
ano/05_03.htm>.
AsiaBizTechAdvanced US MRAM Whips Chip Foes into R&D Catch-up(accessed Jul. 10, 2000) <http://www.nikkeibp.asiabiztech.com
ea/200002/tech_feb.html>.
Electronic DesignMagnetoresistive Technology Holds Promise for Ideal Memory Structures(accessed Jul. 10, 2000) <http://www.elecdesign.com/magazine/1999oct2899/tbrk/1028bkp2.shtml>.
CMPnetNon-volatile RAM designed with magnetic spin valves(accessed Jul. 10, 2000) <http://www.edtn.com
ews/july15/071598tnews5.html>.
Magnetic Random Access Memory(MRAM) (accessed Jun. 21, 2000) <http://www.imec.be/mcp
mc/magneto/mram/mram.htm>.
Science and Technology At AlmadenMagneto-Electronics: Magnetic Tunnel Junctions(accessed Jun. 21, 2000) <http://www.almaden.ibm.com/st/projects/magneto/mtj/>.
James Daughton,Magnetoresistive Random Access Memory(MRAM), Feb. 4, 2000.
Doan Trung T.
Earl Ren
Hineman Max F.
Keller Dennis
Lee Roger
Dickstein , Shapiro, Morin & Oshinsky, LLP
Elms Richard
Micro)n Technology, Inc.
Smith Brad
LandOfFree
Self-aligned, magnetoresitive random-access memory (MRAM)... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Self-aligned, magnetoresitive random-access memory (MRAM)..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Self-aligned, magnetoresitive random-access memory (MRAM)... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3131132