One-time programmable memory
View Patent ↗The present invention provides a programmable memory array including a plurality of memory cells. At least one and preferably each memory cell of the plurality of memory cells include an isolation layer formed of a dielectric material, a field effect transistor, and a programmable element. The programmable element includes a conductive gate, a gate insulator present beneath the conductive gate, and a semiconductor body present under the gate insulator. The semiconductor body of the programmable element is of a different doping type then the doping of the channel region of the field effect transistor. Apart from these components, the memory cell also includes a bit line connected to the source of the field effect transistor, a select word line connected to the gate of the field effect transistor and a program word line connected to the conductive gate of the programmable element.
1. A programmable memory array comprising a plurality of memory cells, at least one memory cell of the plurality of memory cells comprising:
an isolation layer formed of a dielectric material;
a field effect transistor comprising:
a first semiconductor region of a first conductivity type and a second semiconductor region of the first conductivity type, wherein the first semiconductor region and the second semiconductor region are formed over the isolation layer;
a channel region of a second conductivity type formed between the first semiconductor region and the second semiconductor region;
a first gate insulator overlying the channel region; and
a first conductive gate overlying the first gate insulator;
a programmable element comprising:
a third semiconductor region of the first conductivity type;
the second semiconductor region of the first conductivity type;
a semiconductor body present between the second semiconductor region and the third semiconductor region, wherein the third semiconductor region and the semiconductor body are formed over the isolation layer, and, wherein the semiconductor body of the programmable element is undoped;
a second gate insulator overlying the semiconductor body; and
a second conductive gate present over the second gate insulator;
a bit line in contact with the first semiconductor region;
a select word line coupled to the first conductive gate; and
a program word line coupled to the second conductive gate.
2. The programmable memory array of claim 1 , wherein the programmable memory array is a one-time programmable memory array.
3. The programmable memory array of claim 1 , wherein the first conductivity type is N-type and the second conductivity type is P-type.
4. The programmable memory array of claim 1 , wherein the semiconductor body of the programmable element is N-type doped.
5. The programmable memory array of claim 1 , wherein the first semiconductor region is the source region of the field effect transistor and the second semiconductor region is the drain region of the field effect transistor.
6. The programmable memory array of claim 1 , wherein the thickness of the second gate insulator of the programmable element is less than the thickness of the first gate insulator of the field effect transistor.
7. The programmable memory array of claim 1 , wherein the isolation layer is formed over a substrate and the isolation layer is vertically extended upwards in a region adjacent to the third semiconductor region.
8. The programmable memory array of claim 7 , wherein the third semiconductor region is present between the vertically extended region of the isolation layer and the semiconductor body.
9. A programmable memory array comprising a plurality of memory cells, at least one memory cell of the plurality of memory cells comprising:
an isolation layer formed of a dielectric material;
a field effect transistor comprising:
a first semiconductor region of a first conductivity type and a second semiconductor region of the first conductivity type, wherein the first semiconductor region and the second semiconductor region are formed over the isolation layer;
a channel region of a second conductivity type present between the first semiconductor region and the second semiconductor region;
a gate insulator overlying the channel region; and
a first conductive gate overlying the gate insulator;
a programmable element comprising:
the second semiconductor region of the first conductivity type;
a third region present over the isolation layer, wherein the third region is formed of the dielectric material;
a semiconductor body present over the isolation layer, wherein the semiconductor body is present between the second semiconductor region and the third region, and wherein the semiconductor body of the programmable element is undoped;
an insulator layer overlying the semiconductor body; and
a second conductive gate present over the insulator layer;
a bit line in contact with the first semiconductor region;
a select word line coupled to the first conductive gate of the field effect transistor; and
a program word line coupled to the second conductive gate of the programmable element.
10. The programmable memory array of claim 9 , wherein the programmable memory array is a one-time programmable memory array.
11. The programmable memory array of claim 9 , wherein the third region is extended downwards to the isolation layer.
12. The programmable memory array of claim 9 , wherein the first conductivity type is N-type and the second conductivity type is P-type.
13. The programmable memory array of claim 9 , wherein the semiconductor body of the programmable element is N-type doped.
14. The programmable memory array of claim 9 , wherein the first semiconductor region is the source region of the field effect transistor and the second semiconductor region is the drain region of the field effect transistor.
15. The programmable memory array of claim 9 , wherein the thickness of the insulator layer of the programmable element is less than the thickness of the gate insulator of the field effect transistor.
16. The programmable memory array of claim 9 , wherein the isolation layer is formed over a substrate.