Nonvolatile memory element composed of combined superconductor ring and MOSFET

• US 5,332,722 A
• Filed: 03/08/1993
• Issued: 07/26/1994
• Est. Priority Date: 12/02/1987
• Status: Expired due to Fees

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Fujihira, Mitsuka
• Primary Examiner(s): Dixon, Joseph L.
• Assistant Examiner(s): WHITFIELD, MICHAEL
• Application Number:
  US08/028,632
• Time in Patent Office: 505 Days
• Field of Search: 365/160, 365/161, 365/162, 505/1, 505/831, 505/832, 505/833, 505/834, 505/836, 505/841, 257/31, 257/33, 257/421, 257/427
• US Class Current: 505/170
• CPC Class Codes: G11C 11/44 using super-conductive elements, e.g. cryotron
• CPC Class Codes: H01L 29/82 controllable by variation of the magnetic field applied to the device
• CPC Class Codes: Y10S 505/831 Static information storage system or device
• CPC Class Codes: Y10S 505/833 Thin film type
• CPC Class Codes: Y10S 505/841 Random access, i.e. bit organized memory type

Abstract

A novel nonvolatile memory element or cell comprising a memory means consisting of at least one superconducting ring (21, 22) and a detector means consisting of a MOSFET. The superconducting ring and the MOSFET are arranged in such a manner that a magnetic flux created by the superconducting ring (21, 22) passes through a channel zone of the MOSFET. Information is held in the superconducting ring in a form of permanent current and is detected electrically as variation in the conductivity of the channel zone of the MOSFET.

Claims

1. A nonvolatile memory element or cell comprising a memory means consisting of at least one ring formed of a superconductor material so that when the ring is put in a superconducting state, the ring can circulate a permanent electric current therethrough and a detector means consisting of a MOSFET formed in a substrate, said MOSFET including a source region and a drain region formed in a principal surface region of said substrate separated from each other along a principal surface of said substrate, and a channel zone formed between said source region and said drain region, the ring being arranged above and adjacent to said channel zone of said MOSFET in such a manner that a magnetic flux created by current in said ring penetrates and passes through said channel zone of said MOSFET so as to modify a conduction state of said channel zone and wherein said ring is in a plane which is parallel to said principal surface of said substrate and said magnetic flux passes through said channel zone perpendicular to said principal surface of said substrate.

2. A nonvolatile memory element or cell set forth in claim 1, characterized in that one superconducting ring is positioned above the MOSFET and separated therefrom by an insulator.

3. A nonvolatile memory element or cell set forth in claim 1, characterized in that more than one superconducting ring 15 is stacked with respective insulating layers separating them.

4. A nonvolatile memory element or cell set forth in claim 1, characterized in that said at least one ring is composed of superconducting metal or metal alloy.

5. A nonvolatile memory element or cell set forth in claim 1, characterized in that said at least one ring is composed of a compound oxide or a metal oxide complex.

6. A nonvolatile memory element or cell set forth in claim 5, characterized in that said compound oxide is selected from the group consisting of a YBCO type compound oxide superconductor material, a Bi-Sr-Ca-Cu-O system compound oxide superconductor material and a Tl-Ba-Ca-Cu-O system compound oxide superconductor material.

7. A nonvolatile memory element or cell set forth in claim 1 wherein said ring is arranged above and adjacent to said channel zone of said MOSFET with free flux passage between said ring and said channel zone of said MOSFET.

9. A nonvolatile memory element or cell set forth in claim 7 wherein said ring is arranged above and adjacent to said channel zone of said MOSFET with free flux passage between said ring and said channel zone of said MOSFET.

8. A nonvolatile memory element or cell comprising a memory means including at least one ring formed of a superconductor material so that when the ring is put in a superconducting state, the ring can circulate a permanent electric current therethrough and a detector means including a MOSFET formed in a substrate, said MOSFET including a source region and a drain region formed in a principal surface region of said substrate separated from each other along a principal surface of said substrate, and a channel zone formed between said source region and said drain region, the ring being arranged outside of and adjacent to said channel zone of said MOSFET in such a manner that a magnetic flux created by current in said ring penetrates and passes through said channel zone of said MOSFET so as to modify a conduction state of said channel zone and wherein said ring is in a plane which is parallel to said principal surface of said substrate and said magnetic flux passes through said channel zone perpendicular to said principal surface of said substrate.

10. A nonvolatile memory element or cell set forth in claim 8 wherein said MOSFET includes a source electrode in electrical contact with said source, a drain electrode in electrical contact with said drain, and a gate electrode electrically isolated from said memory means and adjacent said channel zone such that voltage applied to said gate electrode affects conductivity in said channel zone.

11. A nonvolatile memory element or cell set forth in claim 10 wherein said gate electrode is at least partially between an interior zone within said at least one ring and said channel zone.

12. A nonvolatile memory element or cell set forth in claim 8 wherein said magnetic flux modifies the conduction state of said channel zone by separating the conduction band and the valence band of semiconductor material within said MOSFET into different levels with predetermined energy levels.

13. A nonvolatile memory element or cell comprising a memory means including at least one ring formed of a superconducting material so that when the ring is put in a superconducting state, the ring can circulate a permanent electric current therethrough and a detector means including a MOSFET formed in a substrate, said MOSFET including a source region and a drain region formed in a principal surface region of said substrate separated from each other along a principal surface of said substrate, and a channel zone formed between said source region and said drain region, the ring being arranged outside of and adjacent to said channel zone of said MOSFET in such a manner that a magnetic flux created by current in said ring penetrates and passes through said channel zone of said MOSFET so as to modify a conduction state of said channel zone such that current in said channel zone is dependent on current in said ring, and wherein there are two rings of superconductor material extending in parallel planes and separated by an insulator, and wherein both of said parallel planes are parallel to said principal surface of said substrate and said magnetic flux passes through said channel zone perpendicular to said principal surface of said substrate.

14. A nonvolatile memory element or cell set forth in claim 13 wherein said ring is arranged above and adjacent to said channel zone of said MOSFET with free flux passage between said ring and said channel zone of said MOSFET.