Magnetoresistive random access memory devices having efficient unit cell layouts
View Patent ↗A semiconductor memory device includes first and second word lines, a bit line, a source line, and a memory cell. The memory cell includes a spin-orbit torque (SOT) pattern having a first end electrically coupled to the source line, a magnetic tunnel junction pattern extending adjacent the SOT pattern, and a read transistor having a first current carrying terminal electrically coupled to a first end of the magnetic tunnel junction pattern, a second current carrying terminal electrically coupled to the bit line, and a gate terminal electrically coupled to the first word line. The memory cell also includes a write transistor having a first current carrying terminal electrically coupled to a second end of the SOT pattern, a second current carrying terminal electrically coupled to the first end of the magnetic tunnel junction pattern, and a gate terminal electrically coupled to the second word line.
1 . A semiconductor memory device, comprising:
a first memory cell having a first spin-orbit torque (SOT) pattern, a first magnetic tunnel junction pattern, a first read transistor, and a first write transistor therein, said first read transistor having a first current carrying terminal electrically connected to a first current carrying terminal of the first write transistor and to a first end of the first magnetic tunnel junction pattern;
a second memory cell having a second spin-orbit torque (SOT) pattern, a second magnetic tunnel junction pattern, a second read transistor, and a second write transistor therein, said second read transistor having a first current carrying terminal electrically connected to a first current carrying terminal of the second write transistor and to a first end of the second magnetic tunnel junction pattern; and
a bit line electrically connected to a second current carrying terminal of the first read transistor and to a second current carrying terminal of the second read transistor through a common dopant region shared by the first read transistor and the second read transistor.
2 . The device of claim 1 , further comprising:
a source line electrically connected to a first end of the first SOT pattern and to a first end of the second SOT pattern; and
wherein a second current carrying terminal of the first write transistor is electrically connected to a second end of the first SOT pattern, and a second current carrying terminal of the second write transistor is electrically connected to a second end of the second SOT pattern.
3 . The device of claim 1 , further comprising:
a first read word line electrically connected to a gate terminal of the first read transistor; and
a second read word line electrically connected to a gate terminal of the second read transistor.
4 . The device of claim 3 , further comprising:
a first write word line electrically connected to a gate terminal of the first write transistor; and
a second write word line electrically connected to a gate terminal of the second write transistor; and
wherein the first and second read word lines extend between the first and second write word lines, and on an active region.
5 . The device of claim 1 ,
wherein each of the first and second magnetic tunnel junction patterns comprises a pinned magnetic pattern, a free magnetic pattern, and a tunnel barrier pattern extending between the pinned and free magnetic patterns;
wherein the first SOT pattern is in contact with the free magnetic pattern within the first magnetic tunnel junction pattern; and
wherein the second SOT pattern is in contact with the free magnetic pattern within the second magnetic tunnel junction pattern.
6 . The device of claim 1 , further comprising:
a semiconductor substrate having an active region therein, which is at least partially defined by a device isolation layer; and
wherein the first and second memory cells are at least partially integrated within the active region.
7 . A semiconductor memory device, comprising:
a device isolation layer, which at least partially defines an active region in a semiconductor substrate;
first and second write word lines overlapping at least a first portion of the active region;
first and second read word lines overlapping at least a second portion of the active region, and extending between the first and second write word lines;
a first dopant region provided in the active region at a side of the first write word line;
a second dopant region provided in the active region at a side of the second write word line;
a first common dopant region provided in the semiconductor substrate and between the first write word line and the first read word line;
a second common dopant region provided in the semiconductor substrate and between the second write word line and the second read word line;
a third common dopant region provided in the semiconductor substrate and shared between the first and second read word lines;
first and second magnetic tunnel junction patterns connected to the first and second common dopant regions, respectively;
first and second spin-orbit torque (SOT) patterns disposed on the first and second magnetic tunnel junction patterns, respectively;
a source line intersecting the first and second write word lines and the first and second read word lines and connected in common to the first and second SOT patterns; and
a bit line intersecting the first and second write word lines and the first and second read word lines and connected to the third common dopant region.
8 . The device of claim 7 , wherein the bit line and the source line are disposed at different heights from the semiconductor substrate.
9 . The device of claim 7 , wherein the first and second SOT patterns are in contact with top surfaces of the first and second magnetic tunnel junction patterns, respectively.
10 . The device of claim 7 , wherein each of the first and second magnetic tunnel junction patterns comprises a pinned magnetic pattern, a free magnetic pattern, and a tunnel barrier pattern between the pinned and free magnetic patterns; and wherein the first and second SOT patterns are in contact with the free magnetic patterns of the first and second magnetic tunnel junction patterns, respectively.
11 . The device of claim 7 , wherein the first and second magnetic tunnel junction patterns are mirror-symmetrical with respect to the third common dopant region when viewed from a plan perspective.
12 . The device of claim 7 , wherein the first magnetic tunnel junction pattern overlaps with the first common dopant region and the second magnetic tunnel junction pattern overlaps with the second common dopant region, when viewed from a plan perspective.
13 . The device of claim 7 , wherein each of the first and second SOT patterns has a longitudinal axis in a direction parallel to the bit line and the source line.
14 . The device of claim 7 , wherein the active region has a longitudinal axis in a direction parallel to the bit line and the source line.
15 . The device of claim 7 , wherein the first and second SOT patterns include a heavy metal material or a material doped with a heavy metal.