14-07-2012, 02:56 PM
Magnetoresistive Random Access Memory (MRAM)
[attachment=27671]
Introduction
In 1984 Drs. Arthur Pohm and Jim Daughton, both employed at that time
by Honeywell, conceived of a new class of magnetoresistance memory devices
which offered promise for high density, random access, nonvolatile memory. In
1989 Dr. Daughton left Honeywell to form Nonvolatile Electronics, Inc. having
entered into a license agreement allowing him to sublicense Honeywell MRAM
technology for commercial applications. Dr. Pohm, Dr. Daughton, and others at
NVE continued to improve basic MRAM technology, and innovated new
techniques which take advantage of revolutionary advances in magnetoresistive
devices, namely giant magnetoresistance and spin dependent tunneling.
Today there is a tremendous potential for MRAM as a nonvolatile, solid
state memory to replace flash memory and EEPROM where fast writing or high
write endurance is required, and in the longer term as a general purpose
read/write random access memory. NVE has a substantial patent portfolio
containing 10 MRAM patents, and is willing to license these, along with 12
Honeywell MRAM patents, to companies interested in manufacturing MRAM. In
addition, NVE is considering internal production of certain niche MRAM products
over the next several years.
Magnetoresistive Random Access Memory (MRAM)
In the mid 1980’s an MRAM concept was developed at Honeywell which
has some common features with most modern versions.
· Writing using magnetic hysteresis
· Reading using magnetoresistance of the same body where data is
stored
· Memory cells integrated on an integrated circuit chip
Figure 3 illustrates the method of data storage in the MRAM cell. The cell
consisted of two ferromagnetic films sandwiching a poor conductor (TaN), with
the composite film etched into stripes as shown. A current through the stripe
Magnetoresistive Random Access Memory (MRAM)
densities competitive with other solid state memory technologies. Not only was
nearly all of the (approximately) 6% GMR available, but also the signal swing
was plus or minus 6%, making the difference between a “0” and “1” about 12% of
the cell resistance. This gave an 8 times improvement over the original mode of
operation, and put MRAM on a much more even footing with semiconductor
memory for read access time.
Spin Dependent Tunneling (SDT) Memory
Spin Dependent Tunneling (SDT) devices provides higher percentage
magnetoresistance than sandwich or PSV structures, and thus has the potential
for higher signals and higher speed. Recent results indicate SDT tunneling
giving over 40% magnetoresistance [13,14] compared to 6-9 %
magnetoresistance in good PSV cells.
[attachment=27671]
Introduction
In 1984 Drs. Arthur Pohm and Jim Daughton, both employed at that time
by Honeywell, conceived of a new class of magnetoresistance memory devices
which offered promise for high density, random access, nonvolatile memory. In
1989 Dr. Daughton left Honeywell to form Nonvolatile Electronics, Inc. having
entered into a license agreement allowing him to sublicense Honeywell MRAM
technology for commercial applications. Dr. Pohm, Dr. Daughton, and others at
NVE continued to improve basic MRAM technology, and innovated new
techniques which take advantage of revolutionary advances in magnetoresistive
devices, namely giant magnetoresistance and spin dependent tunneling.
Today there is a tremendous potential for MRAM as a nonvolatile, solid
state memory to replace flash memory and EEPROM where fast writing or high
write endurance is required, and in the longer term as a general purpose
read/write random access memory. NVE has a substantial patent portfolio
containing 10 MRAM patents, and is willing to license these, along with 12
Honeywell MRAM patents, to companies interested in manufacturing MRAM. In
addition, NVE is considering internal production of certain niche MRAM products
over the next several years.
Magnetoresistive Random Access Memory (MRAM)
In the mid 1980’s an MRAM concept was developed at Honeywell which
has some common features with most modern versions.
· Writing using magnetic hysteresis
· Reading using magnetoresistance of the same body where data is
stored
· Memory cells integrated on an integrated circuit chip
Figure 3 illustrates the method of data storage in the MRAM cell. The cell
consisted of two ferromagnetic films sandwiching a poor conductor (TaN), with
the composite film etched into stripes as shown. A current through the stripe
Magnetoresistive Random Access Memory (MRAM)
densities competitive with other solid state memory technologies. Not only was
nearly all of the (approximately) 6% GMR available, but also the signal swing
was plus or minus 6%, making the difference between a “0” and “1” about 12% of
the cell resistance. This gave an 8 times improvement over the original mode of
operation, and put MRAM on a much more even footing with semiconductor
memory for read access time.
Spin Dependent Tunneling (SDT) Memory
Spin Dependent Tunneling (SDT) devices provides higher percentage
magnetoresistance than sandwich or PSV structures, and thus has the potential
for higher signals and higher speed. Recent results indicate SDT tunneling
giving over 40% magnetoresistance [13,14] compared to 6-9 %
magnetoresistance in good PSV cells.