OTP cell with reversed MTJ connection

• US 9,966,149 B2
• Filed: 03/06/2017
• Issued: 05/08/2018
• Est. Priority Date: 09/13/2012
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Kim, Jung Pill, Kim, Taehyun, Lee, Kangho, Kang, Seung H., Li, Xia, Hsu, Wah Nam
• Primary Examiner(s): Tran, Anthan
• Application Number:
  US15/450,055
• Publication Number:
  US 20170178741A1
• Time in Patent Office: 428 Days
• Field of Search: 365158
• CPC Class Codes: G11C 11/16 using elements in which the storage effect is based on magnetic spin effect
• CPC Class Codes: G11C 11/1673 Reading or sensing circuits or methods
• CPC Class Codes: G11C 11/1675 Writing or programming circuits or methods
• CPC Class Codes: G11C 17/02 using magnetic or inductive elements G11C17/14 takes precedence
• CPC Class Codes: G11C 17/16 using electrically-fusible links
• CPC Class Codes: G11C 17/165 Memory cells which are electrically programmed to cause a change in resistance, e.g. to permit multiple resistance steps to be programmed rather than conduct to or from non-conduct change of fuses and antifuses digital stores using resistance random access memory elements G11C13/0002
• CPC Class Codes: G11C 17/18 Auxiliary circuits, e.g. for writing into memory

Abstract

A one time programming (OTP) apparatus unit cell includes magnetic tunnel junctions (MTJs) with reversed connections for placing the MTJ in an anti-parallel resistance state during programming. Increased MTJ resistance in its anti-parallel resistance state causes a higher programming voltage which reduces programming time and programming current.

Claims

1. A method of programming an anti-fuse magnetic tunnel junction (MTJ) memory cell, comprising:

biasing a free layer for the anti-fuse MTJ memory cell to be negative in voltage with respect to a fixed layer for the anti-fuse MTJ memory cell to force a state of the anti-fuse MTJ memory cell to be an anti-parallel (AP) state; and

breaking down a dielectric barrier layer of the anti-fuse MTJ memory cell while the anti-fuse MTJ memory cell is in the AP state.

2. The method of claim 1, wherein switching the state of the anti-fuse MTJ memory cell comprises:

grounding a free layer of the anti-fuse MTJ memory cell to ground while charging a pinned layer of the anti-fuse MTJ memory cell to a positive voltage.

3. The method of claim 2, wherein grounding the free layer comprises switching on an access transistor to couple the free layer to ground through the access transistor.

4. The method of claim 2, wherein charging the pinned layer comprises charging to the positive voltage a bit line coupled to the pinned layer.

5. The method of claim 1, further comprising integrating the anti-fuse MTJ memory cell into a mobile phone, a set top box, a music player, a video player, an entertainment unit, a navigation device, a computer, a hand-held personal communication systems (PCS) unit, a portable data unit, and/or a fixed location data unit.

6. A method of programming an anti-fuse magnetic tunnel junction (MTJ) memory cell, comprising:

charging a pinned layer of the anti-fuse MTJ memory cell to a voltage that is greater than a voltage of a free layer of the anti-fuse MTJ memory cell to force the anti-fuse MTJ memory cell into an anti-parallel state; and

while the anti-fuse MTJ memory cell is in the anti-parallel state;

maintaining the voltage of the pinned layer higher than the voltage of the free layer until a dielectric barrier layer in the anti-fuse MTJ memory cell is broken down.

7. The method of claim 6, further comprising a step of integrating the anti-fuse MTJ memory cell into a mobile phone, a set top box, a music player, a video player, an entertainment unit, a navigation device, a computer, a hand-held personal communication systems (PCS) unit, a portable data unit, and/or a fixed location data unit.