Method of programming anti-fuse element

• US 5,008,855 A
• Filed: 07/18/1989
• Issued: 04/16/1991
• Est. Priority Date: 07/18/1989
• Status: Expired due to Term

• Current Assignee: Actel Corporation (Microchip Technology Incorporated)
• Original Assignee: Actel Corporation (Microchip Technology Incorporated)
• Inventors: Gluss, David H., Eltoukhy, Abelshafy A.
• Primary Examiner(s): Moffitt, James W.
• Application Number:
  US07/381,630
• Time in Patent Office: 637 Days
• Field of Search: 365/96, 365/225.7
• US Class Current: 365/96
• 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 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

In a method for programming an antifuse element which includes a pair of conductive electrodes separated by an insulating layer a predetermined number of voltage pulses are first applied across the electrodes of the antifuse and the current drawn by the antifuse is simultaneously measured. When the measured current indicates that the antifuse dielectric has ruptured, a second step includes continuing to apply pulses and calculating the difference in current sensed between successive measurements. In a third step, a predetermined number of additional pulses are applied after the difference in current between successive pulses falls below a predetermined threshold. In a fourth step, an additional predetermined number of pulses are applied and the current drawn at the end of the sequence is measured. If it is greater than the current drawn at the beginning of the sequence by a predetermined threshold, the third step is repeated. If not, the programming process ends.

Claims

1. A method of programming an anti-fuse including the steps of:

(1) Applying voltage pulses to said anti-fuse, said voltage pulses including a first portion having a first amplitude less than the voltage necessary to program said anti-fuse, and having a second portion having a second amplitude equal to the voltage necessary to program said anti-fuse,

(2) Measuring the current drawn by said anti-fuse from said second portion of said voltage pulse,

(3) Determining whether said current drawn by said anti-fuse exceeds a predetermined threshold,

(4) Repeating steps 1 through 3 if said current does exceed predetermined threshold,

(5) Applying a series of pulses to said anti-fuse if said current does exceed said predetermined threshold,

(6) Measuring the difference in current drawn by said anti-fuse between successive ones of the voltage pulses applied in step 5,

(7) Repeating step 5 if said difference in current exceeds a predetermined threshold,

(8) Applying a fixed number of pulses if said difference does not exceed said predetermined threshold,

(9) Measuring the current drawn by said anti-fuse at the first and last ones of said fixed number of pulses,

(10) Repeating step 9 if the difference between the current drawn during said first and last ones of said fixed number of rules exceeds a predetermined threshold.