Active solid-state devices (e.g. – transistors – solid-state diode – Integrated circuit structure with electrically isolated... – Passive components in ics
Reexamination Certificate
2000-12-13
2001-08-21
Chaudhuri, Olik (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Integrated circuit structure with electrically isolated...
Passive components in ics
C257S530000, C257S281000, C257S282000, C257S173000
Reexamination Certificate
active
06278171
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to wiring, such as fuses, in semiconductor devices such as dynamic random access memories (DRAMs) and, more specifically, to fuses which can be opened using lower voltages and currents.
2. Description of the Related Art
Dynamic random access memory (DRAM) development technology has recently moved past 256 Mb to 1 Gb. Other technologies are similarly increasing the size of components and the density of components on a given semiconductor chip.
The increase in density on a given chip and the increase in chip size increases the chance of defects within a given product. Therefore, it is very important to include redundant components which can be easily substituted for defective components, using selectively blowable fuses. While some redundancy repair techniques only allow wafer level repair, electrically blowable fuses allow redundant modules within a wafer to replace defective modules on the same wafer.
The key elements important in producing robust and viable electric fuses include ease of use, ability to fabricate the fuse using existing processes and the ability to reliably use a laser to selectively open the fuses. One of the most important parameters in determining the efficiency of an electrical fuse design is the amount of effort it takes to blow (“delete” or “open”) the fuse and maintain the open condition during the fuse's operating life.
Creating a fuse link with a high resistance and increased current density allows the fuse to be blown more easily for a constant input current. Resistive heating generally causes the fuse link material to melt, causes a phase change of the fuse material to a non-conductive state, or causes the fuse material to move away from the fuse link location to prevent the possibility of continued conduction through a blown fuse.
The invention increases the performance of such fuses through a simplified method of forming fuses which are very small (having sub-lithographic feature sizes) and which, therefore, have increased current density.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a self-trimming wiring, such as a fuse structure, and method for forming the same comprising forming a pattern in a photoresist layer by exposure through a phase shift mask over an insulating layer, forming an opening in the insulating layer using the phase shift mask (the opening having vertical sidewalls and sloped sidewalls), depositing a conductive material in the opening, on the vertical sidewalls and on the sloped sidewalls, removing the conductive material from the sloped sidewalls and horizontal surfaces of the opening, wherein the conductive material remains on the vertical sidewalls as fuse links.
The process of forming the opening includes forming the opening to have a minimum lithographic size and the fuse links have a size smaller than the minimum lithographic size. The process of forming the phase shift mask includes forming the phase shift mask to have narrow aperture regions for forming the vertical sidewalls and wide aperture regions for forming the sloped sidewalls. The process of removing the conductive material comprises reactive ion etching. The process of forming the opening includes forming pad areas and the fuse links selectively connect ones of the pad areas. The process of forming the opening forms the vertical sidewalls continuously between ones of the pad areas that are connected and forms the sloped sidewalls between ones of the pad areas that are not connected. The method also includes selectively blowing ones of the fuse links to disconnect elements connected by the fuse links.
REFERENCES:
patent: 4064493 (1977-12-01), Davis
patent: 4597162 (1986-07-01), Johnson et al.
patent: 4679310 (1987-07-01), Ramachandra et al.
patent: 4682204 (1987-07-01), Shiozaki et al.
patent: 4984054 (1991-01-01), Yamada et al.
patent: 5066998 (1991-11-01), Fischer et al.
patent: 5244836 (1993-09-01), Lim
patent: 5420456 (1995-05-01), Galbi et al.
patent: 5472901 (1995-12-01), Kapoor
patent: 5672905 (1997-09-01), Lee et al.
patent: 6015991 (2000-01-01), Wheeler et al.
patent: 57-145357 (1982-09-01), None
patent: 61-147548 (1986-07-01), None
patent: 1-295440 (1989-11-01), None
patent: 6-77180 (1994-03-01), None
Arndt Kenneth C.
Hsu Louis L.
Mandelman Jack A.
Muller K. Paul
C. Li Todd M.
Chaudhuri Olik
International Business Machines - Corporation
McGinn & Gibb PLLC
Nguyen Dilinh
LandOfFree
Sublithographic fuses using a phase shift mask does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sublithographic fuses using a phase shift mask, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sublithographic fuses using a phase shift mask will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2507666