One-time programmable bitcell with native anti-fuse

• US 10,395,745 B2
• Filed: 10/23/2017
• Issued: 08/27/2019
• Est. Priority Date: 10/21/2016
• Status: Active Grant

• Current Assignee: Synopsys Incorporated
• Original Assignee: Synposys Incorporated
• Inventors: Horch, Andrew E., Niset, Martin Luc Cecil Arthur, Hu, Ting-Jia
• Primary Examiner(s): Bernstein, Allison
• Application Number:
  US15/791,023
• Publication Number:
  US 20180114582A1
• Time in Patent Office: 673 Days
• 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
• CPC Class Codes: H01L 23/5252 comprising anti-fuses, i.e. connections having their state changed from non-conductive to conductive
• CPC Class Codes: H01L 29/665 using self aligned silicidation, i.e. salicide formation of conductive layers comprising silicides H01L21/28518
• CPC Class Codes: H01L 29/78 with field effect produced by an insulated gate H01L29/7725, H01L29/775, H01L29/778 take precedence
• CPC Class Codes: H01L 29/7833 with lightly doped drain or source extension, e.g. LDD MOSFET's; DDD MOSFET's for thin film transistors H01L29/78618
• CPC Class Codes: H10B 20/25 One-time programmable ROM [OTPROM] devices, e.g. using electrically-fusible links

Abstract

A one-time programmable memory device includes a well of a first polarity in a semiconductor substrate. A lightly-doped drain (LDD) region is above one portion of the well. The LDD region has a first doping concentration and a second polarity that is opposite the first polarity. A source region or a drain region of the second polarity is above another portion of the well. The source region or the drain region has a second doping concentration that is higher than the first doping concentration. A first breakdown voltage between the LDD region and the well region is higher than a second breakdown voltage between the source region or the drain region and the well region. A select device is positioned at least partially above a portion of the source region or the drain region. The select device is configured to form a channel between the source region or the drain region and the LDD region. An anti-fuse device is positioned at least partially above a portion of the LDD region.

Claims

1. A one-time programmable memory device comprising:

a well region of a first polarity in a semiconductor substrate;

a lightly-doped drain (LDD) region above a first portion of the well region, the LDD region having a second polarity that is opposite the first polarity and having a first doping concentration;

a source region or a drain region of the second polarity above a second portion of the well region, the source region or the drain region having a second doping concentration that is higher than the first doping concentration, and a first breakdown voltage between the LDD region and the well region is higher than a second breakdown voltage between the source region or the drain region and the well region;

a select device positioned at least in part above a portion of the source region or the drain region, the select device configured to form a channel between the source region or the drain region and the LDD region;

an anti-fuse device positioned at least in part above a portion of the LDD region; and

a shallow trench isolation (STI) region adjacent to the LDD region, wherein the LDD region extends underneath the anti-fuse device to the STI region.

2. The one-time programmable memory device of claim 1, wherein:

the select device comprises a gate oxide of a first thickness and a conductive gate above the gate oxide; and

the anti-fuse device comprises a gate oxide of a second thickness thinner than the first thickness.

3. The one-time programmable memory device of claim 1, wherein the select device comprises a first implant having the second polarity, and the anti-fuse device comprises a second implant having the second polarity.

4. The one-time programmable memory device of claim 3, wherein a salicide is formed in the source region or the drain region and at least a portion of the second implant.

5. The one-time programmable memory device of claim 4, wherein a salicide is not formed in the LDD region.

6. The one-time programmable memory device of claim 1, wherein the first breakdown voltage between the LDD region and the well region is at least one volt higher than the second breakdown voltage between the source region or the drain region and the well region.

7. The one-time programmable memory device of claim 1, wherein the second doping concentration is higher than the first doping concentration by at least a factor of 10.

8. The one-time programmable memory device of claim 1, wherein the memory device is configured to be programmed by applying a rupture voltage at the anti-fuse device to rupture a gate oxide of the anti-fuse device.

9. A non-transitory computer-readable storage medium storing instructions thereon for execution by processor(s) to perform a method of manufacturing a one-time programmable memory device, the one-time programmable memory comprising:

a well region of a first polarity in a semiconductor substrate;

a lightly-doped drain (LDD) region above a first portion of the well region, the LDD region having a second polarity that is opposite the first polarity and having a first doping concentration;

a source region or a drain region of the second polarity above a second portion of the well region, the source region or the drain region having a second doping concentration that is higher than the first doping concentration, and a first breakdown voltage between the LDD region and the well region is higher than a second breakdown voltage between the source region or the drain region and the well region;

a select device positioned at least in part above a portion of the source region or the drain region, the select device configured to form a channel between the source region or the drain region and the LDD region;

an anti-fuse device positioned at least in part above a portion of the LDD region; and

a shallow trench isolation (STI) region adjacent to the LDD region, wherein the LDD region extends underneath the anti-fuse device to the STI region.

10. The non-transitory computer-readable storage medium of claim 9, wherein:

the select device comprises a gate oxide of a first thickness and a conductive gate above the gate oxide; and

the anti-fuse device comprises a gate oxide of a second thickness thinner than the first thickness.

11. The non-transitory computer-readable storage medium of claim 9, wherein the select device comprises a first implant having the second polarity, and the anti-fuse device comprises a second implant having the second polarity.

12. The non-transitory computer-readable storage medium of claim 11, wherein a salicide is formed in the source region or the drain region and at least a portion of the second implant.

13. The non-transitory computer-readable storage medium of claim 12, wherein a salicide is not formed in the LDD region.

14. The non-transitory computer-readable storage medium of claim 9, wherein the first breakdown voltage between the LDD region and the well region is at least one volt higher than the second breakdown voltage between the source region or the drain region and the well region.

15. The non-transitory computer-readable storage medium of claim 9, wherein the second doping concentration is higher than the first doping concentration by at least a factor of 10.

16. The non-transitory computer-readable storage medium of claim 9, wherein the memory device is configured to be programmed by applying a rupture voltage at the anti-fuse device to rupture a gate oxide of the anti-fuse device.