Construction and application for non-volatile, reprogrammable switches

• US 6,319,773 B1
• Filed: 03/02/2000
• Issued: 11/20/2001
• Est. Priority Date: 02/26/1999
• Status: Expired due to Fees

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Noble, Wendell P., Cloud, Eugene H.
• Primary Examiner(s): CHAUDHARI, CHANDRA P
• Application Number:
  US09/517,036
• Time in Patent Office: 628 Days
• Field of Search: 438/201, 438/210, 438/211, 438/241, 438/258, 438/267, 438/275, 438/593
• US Class Current: 438/258
• CPC Class Codes: G11C 16/0441 comprising cells containing multiple floating gate devices, e.g. separate read-and-write FAMOS transistors with connected floating gates
• CPC Class Codes: G11C 16/045 Floating gate memory cells with both P and N channel memory transistors, usually sharing a common floating gate
• CPC Class Codes: H01L 29/40114 the electrodes comprising a conductor-insulator-conductor-insulator-semiconductor structure
• CPC Class Codes: H10B 69/00 Erasable-and-programmable ROM [EPROM] devices not provided for in groups H10B41/00 - H10B63/00, e.g. ultraviolet erasable-and-programmable ROM [UVEPROM] devices

Abstract

The present invention includes a DRAM technology compatible non-volatile, reprogrammable switch formed according to an DRAM optimized process flow. The non-volatile, reprogrammable switch includes a non-volatile memory cell. The non-volatile memory cell includes a first metal oxide semiconductor field effect transistor (MOSFET) formed in a semiconductor substrate. A capacitor is formed in a subsequent layer above the first MOSFET and is separated from the MOSFET by an insulator layer. A vertical electrical via couples a bottom plate of the capacitor through the insulator layer to a gate of first MOSFET. A second MOSFET is formed in the semiconductor substrate. The gate of the first MOSFET also serves as a gate of the second MOSFET. Additional MOSFETs can be combined in a similar fashion with the non-volatile cell to create a new, powerful logic cell that is smaller and more robust than conventional circuit solutions. The present invention includes applications such as a very size efficient address decode tree, data routing device, or other applications such as used in DRAM redundancy schemes. Methods for forming and using the present invention are also included. The need for intervening sense amps normally required to read the status of a non-volatile memory cell (e.g. an EEPROM cell) and communicate this to additional logic that would then in turn control the status of one or more switches is eliminated. Thus, the requirements of low power densely packed integrated circuits is realized for smaller, portable microprocessor devices.

Claims

1. A method for forming a non-volatile, reprogrammable switch, comprising:

forming a non-volatile memory cell, wherein forming the non-volatile memory cell includes;

forming a first metal oxide semiconductor field effect transistor (MOSFET) in a semiconductor substrate;

forming a capacitor; and

forming a vertical electrical via, wherein forming the vertical electrical via includes coupling a bottom plate of the capacitor through an insulator layer to a gate of first MOSFET; and

forming a second MOSFET in the semiconductor substrate, wherein forming the first MOSFET includes forming the gate of the first MOSFET as a gate for of the second MOSFET.

2. The method of claim 1, wherein forming the capacitor includes forming a top plate which serves as a control gate for non-volatile memory cell.

3. The method of claim 1, wherein forming the capacitor includes forming the bottom plate in a cup shaped having interior walls and exterior walls and which is separated by a capacitor dielectric from a top plate.

4. The method of claim 3, wherein forming the capacitor includes forming the capacitor dielectric conformal to the bottom plate, forming the top plate conformal to the capacitor dielectric, wherein a portion of the top plate is located within the interior walls of the bottom plate.

5. The method of claim 1, wherein forming the capacitor includes forming a stacked capacitor formed according to a dynamic random access memory (DRAM) process flow.

6. The method of claim 1, wherein forming the non-volatile memory cell includes forming the non-volatile memory cell as a programming element, and includes forming the bottom plate of the capacitor as a floating gate.

7. The method of claim 1, wherein forming the second MOSFET includes forming the second MOSFET as a switching element, wherein the switching element is “

on”

when the floating gate is in a first programmed state, and wherein the switching element is “

off”

when the floating gate is in a second programmed state.

8. The method of claim 1, wherein forming the non-volatile, reprogrammable switch further includes coupling an output node for the second MOSFET to another circuit component on an integrated circuit.

9. A method for forming a non-volatile, reprogrammable switch, comprising:

forming a non-volatile memory cell, wherein forming the non-volatile memory cell includes;

forming a first metal oxide semiconductor field effect transistor (MOSFET) in a semiconductor substrate;

forming a stacked capacitor above a gate of the first MOSFET using a DRAM process; and

electrically coupling a bottom plate of the stacked capacitor to the gate of the first MOSFET;

forming a second MOSFET in the semiconductor substrate, wherein forming the first MOSFET includes forming the gate of the first MOSFET as a gate for of the second MOSFET; and

forming third MOSFET in the semiconductor substrate, wherein forming the first MOSFET includes forming the gate of the first MOSFET as a gate for of the third MOSFET.

10. The method of claim 9, wherein electrically coupling the bottom plate of the stacked capacitor to the gate of the first MOSFET includes forming a polysilicon plug.

11. The method of claim 9, wherein forming the second MOSFET includes forming an n-channel metal oxide semiconductor (NMOS) transistor, and wherein forming the third MOSFET includes forming a p-channel metal oxide semiconductor (PMOS) transistor.

12. The method of claim 9, wherein forming the stacked capacitor includes forming a top plate of the stacked capacitor as a control gate for the non-volatile memory cell.

13. The method of claim 9, wherein forming the non-volatile memory cell includes forming the non-volatile memory cell as a programming element, and includes forming the bottom plate of the stacked capacitor as a floating gate.

14. The method of claim 13, wherein forming the second and the third MOSFETs includes forming the second and the third MOSFETs as a switching elements, wherein the second MOSFET is “

on” and

the third MOSFET is “

off”

when the floating gate is in a first programmed state, and wherein the second MOSFET is “

off” and

the third MOSFET if “

on”

when the floating gate is in a second programmed state.