US 2012O314475A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2012/0314475A1 L (43) Pub. Date: Dec. 13, 2012 (54) LOW VOLTAGE PROGRAMMABLE MOSFET (52) U.S. Cl. ........................................................ 365/104 ANTIFUSE WITH BODY CONTACT FOR DIFFUSION HEATING (57)57 ABSTRACT An antifuse can include an insulated gate field effect transis (75) Inventor: YANZUN LI, Lagrangeville, NY tOr “IGFET) havingaV1ng an active Sem1COnductOrreg1Onicond gion 1ncludinclud (US) ing a body and first regions, i.e., at least one source region and at least one drain region separated from one another by the body. A gate may overlie the body and a body contact is (73) Assignee: INTERNATIONAL BUSINESS electrically connected with the body. The first regions have MACHINES CORPORATION, opposite conductivity (i.e., n-type or p-type) from the body. Armonk, NY (US) The IGFET can be configured such that a programming cur rent through at least one of the first regions and the body (21) Appl. No.: 13/158,510 contact causes heating sufficient to drive dopant diffusion from the at least one first region into the body and cause an (22) Filed: Jun. 13, 2011 edge of the at least one first region to move closer to an adjacent edge of at least one other of the first regions. In Such way, the programming current can permanently reduce elec Publication Classification trical resistance by one or more orders of magnitude between (51) Int. Cl. the at least one first region and the at least one other first GITC 17/08 (2006.01) region. 122 118 118 116 Patent Application Publication Dec. 13, 2012 Sheet 1 of 8 US 2012/031447S A1 Patent Application Publication Dec. 13, 2012 Sheet 2 of 8 US 2012/031447S A1 PFET W I 11 OA- 12A FIG. 3 230 Current (A) ? Patent Application Publication Dec. 13, 2012 Sheet 3 of 8 US 2012/031447S A1 Resistance time FIG. 5 335 OO 334 FIG. 6 104 Patent Application Publication Dec. 13, 2012 Sheet 4 of 8 US 2012/031447S A1 436 400 440 440 41 OB 432-IO Old 432 - Sa 2F. T 412Al4O OF 412B 432 D D alD D, N.432 41 OB 410A FIG. 7 NFET 512 Patent Application Publication Dec. 13, 2012 Sheet 5 of 8 US 2012/031447S A1 500 566 536 568 FIG. 9 600 F.G. 10 Patent Application Publication Dec. 13, 2012 Sheet 6 of 8 US 2012/031447S A1 802 Patent Application Publication Dec. 13, 2012 Sheet 7 of 8 US 2012/031447S A1 900 NFET 902 1012 Patent Application Publication Dec. 13, 2012 Sheet 8 of 8 US 2012/031447S A1 1112 US 2012/0314475 A1 Dec. 13, 2012 LOW VOLTAGE PROGRAMMABLE MOSFET (“IGFET). An active semiconductor region of the IGFET ANTIFUSE WITH BODY CONTACT FOR includes a body, and first regions being at least one source DIFFUSION HEATING region and at least one drain region separated from one another by the body. A gate may overlie the body and a body BACKGROUND OF THE INVENTION contact is electrically connected with the body. The first regions have a first conductivity type being one of n-type or 0001 1. Field of the Invention p-type, and the body has a second conductivity type being one 0002 The subject matter of the present application relates of n-type or p-type and opposite the first conductivity type. In to electrical antifuses, especially Such devices provided in such embodiment, the IGFET is configured such that a pro integrated circuit chips. gramming current through at least one of the first regions and 0003 2. Description of the Related Art the body contact causes heating within the body which is 0004 Integrated circuit chips often include elements sufficient to drive dopant diffusion from the at least one first which can be permanently altered after manufacture in order region into the body, and cause an edge of the at least one first to make certain changes to circuits therein, or to maintain region to move closer to an adjacent edge of at least one other states or data on the chip. For example, an integrated circuit of the first regions, thus permanently reducing electrical resis chip can include electrically operable fuses or an array of tance between the at least one first region and the at least one fuses to store critical information on chip, to conduct redun other first region by one or more orders of magnitude. dancy repair to improve manufacturing yield, or to fine tune 0008. In one example of such embodiment, the at least one circuit performance through local circuit trimming, among first region may include at least one source region and at least other purposes. Such fuses initially begin as conductive ele one drain region of the antifuse, and the IGFET is configured ments, i.e., devices which are closed circuit in that initially, Such that programming currents through the source region to they are electrically connected between external terminals. A the body contact and through the drain region to the body fuse can be programmed, i.e., blown, to make it much less contact cause heating within the body sufficient to drive conductive, i.e., open circuited in that it effectively is no dopant diffusion from each of the source region and drain longer electrically connected between external terminals. region into the body and cause edges of each of the source Electrical antifuses are alternative structures which can be region and the drain region to move closer to one another. provided on an integrated circuit. Such antifuses typically 0009. In a particular example of such embodiment, the begin as elements which are essentially nonconductive, hav body may include at least two branch body portions which are ing high electrical resistance (i.e., open circuit state). Pro separated from one another by at least one of the first regions gramming an antifuse greatly reduces the electrical resistance and a connecting body portion that connects the at least two of the antifuse to a level at which the antifuse is electrically branch body portions. The gate of the IGFET in such embodi connected between external terminals, achieving in effect a ment may have corresponding gate portions overlying respec closed circuit state. tive ones of the branch and connecting body portions. In Such 0005 One challenge faced by electrical fuses and anti example, the at least one source region may include first and fuses used in integrated circuit chips is the ability to reliably second source regions separated from one another by the program the fuse or antifuse. During programming, an elec connecting body portion and the at least one drain region may trical fuse may require a metal fuse link to melt under high include first and second drain regions separated from one current, which can cause local explosion with metal particles another by the connecting body portion. scattered far away from the blown fuse or stress cracks to 0010. In a particular example, the at least one source form in adjacent dielectric materials and affect nearby cir region can include first and second source regions separated cuits. In some existing electrical antifuses, a high Voltage is from one another by the branch body portions and the at least applied across a thin dielectric layer to create a localized one drain region is disposed between at least two of the breakdown that is electrically conductive. These types of branch body portions. fuses and antifuses can sometimes fail to change completely to a programmed State. Such that a fuse can remain relatively 0011. In a particular example, the IGFET can be config conductive even after programming, and an antifuse may ured such that the programming current can be applied by remain too resistive after programming. In some cases, only applying a Voltage between the at least one first region and the 90-99% of these devices work properly when programmed. body which is less than twice a nominal maximum Voltage Another challenge for many of the fuse or antifuse solutions between the at least one first region and the gate usable to today which utilize such destructive mechanisms is the ability operate the IGFET in an on-state. to maintain the programmed State of the fuse or antifuse 0012. In a particular example, the IGFET can be config throughout its useful lifetime. In aggravated application envi ured such that the programming current can be applied by ronments such as high temperature, Some programmed fuses applying a programming Voltage between the at least one first and antifuses may gradually change back into their previous region and the body which is approximately equal to a nomi unprogrammed States. nal maximum Voltage between the at least one first region and 0006 Moreover, fuses and antifuses may require special the gate usable to operate the IGFET in an on-state. high Voltage levels not available on the integrated circuit chip 0013. In a particular example, the antifuse can be config for programming them. This can pose design challenges for ured such that application of the programming current to the Supplying the Voltage levels on the chip and contributes to the antifuse causes the edge of the at least one first region to move overall cost of making the chip. Sufficiently to overlap the adjacent edge of the at least one other first region. SUMMARY OF THE INVENTION 0014. In a particular example, the antifuse can be config ured such that when the antifuse is in an unprogrammed State 0007 An antifuse according to an embodiment of the a resistance between the at least one source region and the at invention can include an insulated gate field effect transistor least one drain region is higher than 100,000 ohms and when US 2012/0314475 A1 Dec.