Semiconductor device manufacturing: process – Making device array and selectively interconnecting – Using structure alterable to conductive state
Reexamination Certificate
1999-06-08
2001-07-03
Nelms, David (Department: 2818)
Semiconductor device manufacturing: process
Making device array and selectively interconnecting
Using structure alterable to conductive state
C438S467000
Reexamination Certificate
active
06255144
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a repairing fuse for semiconductor devices. More particularly, the present invention relates to a fuse whose repairing mechanism is conducted in such a way that it is connected with another fuse, instead of being destroyed. Also, the present invention is concerned with a method for fabricating such a repairing fuse.
2. Description of the Prior Art
In semiconductor memory devices, redundancy cells are generally provided by sub-array blocks. For instance, to substitute for defective memory cells by row/column units, redundant rows and columns are prepared in every 256K cell aeries. Typically, after completion of wafer scale integration, testing is conducted to select defective memory cells. If any defective memory cell is detected, programming is executed in the internal circuit to convert its address into that of a corresponding redundancy cell through a repair circuit. Accordingly, if the address corresponding to a defective line is input, the line of the redundancy cells is selected and works in practical use.
Usually, the programming is conducted in an electric fusing technique in which an overcurrent is used to melt a fuse till it disconnects or in a laser beam fusing technique in which a laser beam is used to incapacitate a fuse. Of these techniques, the laser beam fusing technique is preferred by virtue of its simplification and reliability in addition to its ability to be easily laid out. However, this technique suffers from disadvantages in that a control is required to leave an appropriate thickness of a residual oxide on a single layer or multilayer polysilicon structure which is used as a fuse and that the oxide in a small sized fuse box should be etched to a deep extent upon repair (or pad) etching. Another disadvantage of the laser beam fusing technique is that the size of the fuse is inconveniently adjusted to the focal size of the laser beam when shrunk.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to overcome the above problems encountered in prior arts and to provide a repairing fuse for semiconductor devices, which allows the simplification of a repairing process with an improvement in the yield.
It is another object of the present invention to provide a method for fabricating such a fuse.
In accordance with an embodiment of the present invention, there is provided a repairing fuse for semiconductor devices, comprising: a first conducting film which is formed in a contact hole with a connection to a bottom wire layer atop a semiconductor substrate, the contact hole having a lower part narrower than its upper part and being formed in an interlayer insulating film deposited on the wire layer; and a plurality of second conducting films which are disconnected with each other, each having an end point at a predetermined part of the slant wall of the contact hole, wherein the first conducting film and the second conducting films are mutually connected upon illumination of a laser beam so as to repair the semiconductor devices.
In order to fabricate such a repairing fuse, there is provided a method, comprising the steps of: forming an interlayer insulating film on a planarized surface of a bottom wire layer atop a semiconductor substrate; opening the insulating film to form a contact hole through which a predetermined region is exposed, the contact hole having a lower part narrower than its upper part; filling a first conducting film in the narrow lower part of the contact hole, the first conducting film being in contact with the bottom wire layer; and forming second conducting film patterns, which are disconnected with each other at a region atop the first conducting film with an end point at a predetermined part on the slant wall of the upper part of the contact hole. Optionally, following this, the method may further comprises the steps of: depositing an insulating film over the resulting structure; selectively etching the insulating film with the aid of a repairing mask pattern to expose the first conducting film and the second conducting film; and illuminating a laser beam on the first conducting film and the second conducting film to connect them mutually.
In accordance with another embodiment of the present invention, there is provided a repairing fuse for semiconductor devices, comprising disconnected conducting patterns each of which is formed over an interlayer insulating film, filling a contact hole with a connection to a bottom wire pattern, the contact hole having a lower part narrower than its upper part and being formed in the interlayer insulating film deposited on the wire layer atop a semiconductor substrate, wherein the disconnected conducting patterns are connected mutually upon illumination of a laser beam so as to repair the semiconductor devices.
In order to fabricate such a repairing fuse, there is provided a method, comprising the steps of: depositing an interlayer insulating film on a planarized surface of bottom wire patterns formed on a semiconductor substrate; constructing in the interlayer insulating film contact holes which each has a narrower diameter in a lower part than in an upper part and exposes a predetermined area of the bottom wire patterns therethrough; and forming conducting patterns in the contact holes with connections to the bottom wire patterns, the conducting patterns being disconnected with each other and extending over the interlayer insulating film. Optionally, following this, the method may further comprise the steps of: depositing an insulating film over the resulting structure; selectively etching the insulating film with the aid of a repairing mask pattern to expose the conducting patterns; and illuminating a laser beam on the conducting patterns to connect them mutually.
In the present invention, a contact hole process and a wiring process are, in sequence, conducted, resulting in the formation of a fuse consisting of a conducting film filled in the contact hole and a conducting film on an interlayer insulating film. These two conducting films are in a disconnection state and, when illumination of a laser beam, are connected with each other for repairing.
REFERENCES:
patent: 4792835 (1988-12-01), Sacarisen et al.
patent: 5793094 (1998-08-01), Sanchez et al.
patent: 5970346 (1999-10-01), Liaw
patent: 4-300081 (1992-10-01), None
patent: 4-355972 (1992-12-01), None
patent: 7-74254 (1995-03-01), None
patent: 9-312342 (1997-12-01), None
Chang Myeung Sik
Jeon Bae Keun
Oh Choon Sik
Park Sung Wook
Hyundai Electronics Industries Co,. Ltd.
Nelms David
Nhu David
Oliff & Berridge PLC.
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