Programming of antifuses

• US 5,471,154 A
• Filed: 01/13/1995
• Issued: 11/28/1995
• Est. Priority Date: 07/31/1991
• Status: Expired due to Term

• Current Assignee: QuickLogic Corporation
• Original Assignee: QuickLogic Corporation
• Inventors: Chan, Andrew K., Gordon, Kathryn E.
• Primary Examiner(s): Westin, Edward P.
• Assistant Examiner(s): ROSEEN, RICHARD R
• Application Number:
  US08/372,611
• Time in Patent Office: 319 Days
• Field of Search: 326/38, 326/100, 327/525, 257/530, 365/96, 365/225.7, 437/170, 437/172
• US Class Current: 326/38
• CPC Class Codes: G11C 17/18 Auxiliary circuits, e.g. for writing into memory
• CPC Class Codes: H01L 21/76888 By rendering at least a portion of the conductor non conductive, e.g. oxidation
• 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
• CPC Class Codes: H01L 2924/3011 Impedance

Abstract

The invention allows programming an antifuse so as to reduce the antifuse resistance and the standard deviation of the resistance without increasing the programming current. This is achieved by passing current pulses of the opposite polarity through the antifuse. In some embodiments, the magnitude of the second pulse is lower than the magnitude of the first pulse. Further, if the antifuse is formed on a semiconductor substrate with one electrode on top of the other electrode and on top of the substrate, the current during the first pulse flows from the top electrode to the bottom electrode and not vice versa. A programming circuitry is provided that allows to program antifuses in a programmable circuit. A driver circuit is connected to each "horizontal" channel and each "vertical" channel. Each driver circuit is controlled by data in the driver circuit. The driver circuits are connected into shift registers so that all the data can be entered from one, two, three or four inputs. No decoding circuitry is necessary. Before programming, the drivers precharge all the channels to an intermediate voltage. During programming, the channels that are not directly connected to the antifuse being programmed are switched to high impedance. As a result, the power consumption is reduced and the programming proceeds faster.

Claims

1. A method for programming an antifuse, the method comprising the steps of:

generating a first current pulse through the antifuse to program the antifuse; and

generating a second current pulse through the antifuse of a polarity opposite from the polarity of the first pulse,

wherein the antifuse resistance after the second pulse is below 100 ohms.

2. The method of claim 1 wherein the antifuse comprises:

a first electrode;

a dielectric overlaying the first electrode and having an opening therethrough;

a programmable material overlaying and contacting the first electrode in the opening;

insulating spacers around the sidewalls of the opening; and

a second electrode overlaying and contacting the programmable material.