Access transistor with a buried gate
View Patent ↗A magnetic memory cell is formed including a magneto tunnel junction (MTJ) and an access transistor, which is used to access the MTJ in operation. The access transistor, which is formed on a silicon substrate, includes a gate, drain and source with the gate position substantially perpendicular to the plane of the silicon substrate thereby burying the gate and allowing more surface area on the silicon substrate for formation of additional memory cells.
1. A magnetic memory cell including a magneto tunnel junction (MTJ) accessed for reading and writing, the magnetic memory cell comprising:
a source formed in a silicon substrate;
a transistor channel area formed in a portion of the source;
a gate formed on a different portion of the source and substantially adjacent to the transistor channel area where a first channel is formed and a second channel formed on an opposite side of the first channel;
a drain formed on top of the transistor channel area, the drain, the gate, and the source collectively comprising an access transistor operative to access a magneto tunnel junction (MTJ);
the MTJ formed on top of and coupled to the drain and operative to be accessed by the access transistor;
a bit line formed on top of and coupled to the MTJ; and
a word line formed above the bit line and coupled to the gate,
wherein the source, the drain, the gate, and the transistor channel area are buried in the silicon substrate.
2. The magnetic memory cell, as recited in claim 1 , further comprising a gate oxide formed on either side or the gate, between the gate and the transistor channel area.
3. The magnetic memory cell, as recited in claim 1 , further comprising an isolation layer formed on top of the bit line.
4. The magnetic memory cell, as recited in claim 1 , wherein the magnetic memory cell is 5 F 2 .
5. The magnetic memory cell, as recited in claim 1 , wherein the source is made of n-region, the drain is made of n-region and the transistor channel area is made of p-region.
6. The magnetic memory cell, as recited in claim 1 , wherein the source is made of p-region, the drain is made of p-region and the transistor channel area is made of n-region.