Variable circuit connector and method of fabricating the same

Method for forming a variable circuit connector in a wafer having a plurality of circuit modules, is disclosed, which allows selective cut-off and connection between circuit modules, including the steps of forming an insulating layer on an entire surface of the wafer inclusive of a plurality of connecting layers connected to terminals on the circuit modules, and injecting conductive ions into the insulating layer between the connecting layers intended to connect to each other.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a semiconductor device and method of 
fabricating the same, and more particularly, to a variable circuit 
connector which allows selective cut-off and connection between circuit 
modules and method of forming the same. 
2. Discussion of the Related Art 
FIG. 1 illustrates a conceptual drawing for explaining a background art 
connector positioned between semiconductor circuit modules. In general, a 
wafer fabricated with a plurality modules thereon is tested before 
packaging. After the test, circuit modules which are determined to be 
defective should be cut-off. That is, after testing modules, circuit 
modules that are determined to be defective and circuit modules that 
operate properly but should not be connected to any other circuit modules 
are cut-off. 
Each module has input and output points (inclusive of pads) on the circuit 
that are connected by a fuse 11. The fuse 11, connecting the circuit 
modules, is used to control the connection of a module to other modules. A 
fuse 11 is cut to isolate a defective or otherwise separated module 
according to the following two methods: (1) flowing an overcurrent through 
the fuse connected to the circuit module intended to cut-off, and (2) 
directing a laser beam to the connection point(fuse) between the circuit 
modules to burn the fuse off. Thus, circuit modules which are determined 
to be defective and circuit modules which should not be connected to any 
other circuit modules are cut-off using the aforementioned methods. 
However, connection between the required circuit modules after completion 
of this testing is sometimes impossible, reducing selectivity and overall 
yield. 
SUMMARY OF THE INVENTION 
The present invention is directed to a variable circuit connector and a 
method of forming the same that substantially obviate one or more of the 
above and other problems due to limitations and disadvantages of the 
related art. 
An object of the present invention is to provide a variable circuit 
connector and a method of forming the same which are capable of 
selectively connecting circuit modules after the circuit modules are 
tested. 
Additional features and advantages of the invention will be set forth in 
the description which follows, and in part will be apparent from the 
description, or may be learned by practice of the invention. The 
objectives and other advantages of the invention will be realized and 
attained by the structure particularly pointed out in the written 
description and claims hereof as well as the appended drawings. 
To achieve these and other advantages and in accordance with the purpose of 
the present invention, as embodied and broadly described, the method for 
forming a variable circuit connector in a wafer having a plurality of 
circuit modules, includes the steps of forming an insulating layer on an 
entire surface of the wafer inclusive of a plurality of connecting layers 
connected to terminals on the circuit modules, and injecting conductive 
ions into the insulating layer between the connecting layers intended to 
connect to each other. 
In addition, the variable circuit connector includes a variable circuit 
connector for connecting at least two circuit modules plural distinct 
connecting layers connected to terminals on the circuit modules, and the 
variable circuit connector including a separating layer separating the 
distinct connecting layers, the layer enabling electrical connection 
between at least two distinct connecting layers. The separating layer is 
an insulating layer that is selectively biased to enable electrical 
connection between at least two distinct connecting layers, the insulating 
layer having selective portions that include conductive ions used to 
enable the electrical connection between the distinct connecting layers. 
The insulating layer is fabricated from at least one of silicon oxide and 
silicon. The insulating layer may also include ions of a conductivity type 
opposite the conductive ions enabling electrical connection between the 
distinct connecting layers, which second ions neutralize the conductivity 
ions to prevent a flow of charge between the distinct connecting layers. 
It is to be understood that both the foregoing general description and the 
following detailed description are exemplary and explanatory and are 
intended to provide further explanation of the invention as claimed. Thus, 
it should be understood that the detailed description and specific 
examples, while indicating preferred embodiments of the invention, are 
given by way of example only. Various changes and modifications that are 
within the spirit and scope of the invention will become apparent to those 
skilled in the art from this detailed description. In fact, other objects, 
features and characteristics of the present invention; methods, operation, 
and functions of the related elements of the structure; combinations of 
parts; and economies of manufacture will surely become apparent from the 
following detailed description of the preferred embodiments and 
accompanying drawings, all of which form a part of this specification, 
wherein like reference numerals designate corresponding parts in various 
figures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Reference will now be made in detail to the preferred embodiments of the 
present invention, examples of which are illustrated in the accompanying 
drawings. 
FIGS. 2A.about.2C illustrate sectional views of a variable circuit 
connector illustrating a method for forming that variable circuit 
connector in accordance with a first preferred embodiment of the present 
invention. 
Referring to FIG. 2A, the method starts with the step of forming an 
insulating layer 23 on a wafer 21 having a plurality of connecting layers 
22 formed thereon. Each of the connecting layers 22 is a conductor 
connected to a terminal on the circuit module, inclusive of pads. Thus, in 
the present invention, there are a plurality of circuit modules which are 
independent from each other on a wafer. 
Entire background art circuit modules are connected with fuses, and when 
unnecessary circuit modules are intended to be cut off as a result of a 
test, the fuses connected to the unnecessary circuit modules are cut off 
selectively. By contrast, in the present invention, circuit modules are 
fabricated independently from the beginning and connected by selectively 
injecting ions into portions of circuit system. 
That is, the insulating layer 23 is formed on an entire surface of the 
wafer 21 inclusive of the plurality of independently formed connecting 
layers 22. In a later step, portions of the insulating layer 23 are used, 
where appropriate, as connectors for electrically connecting the 
connecting layers 22 spaced apart from each other. The insulating layer 23 
is formed of silicon oxide or an insulating film which acts as a conductor 
upon injection of silicon or a conductive ions. 
Then, as shown in FIG. 2B, a photoresist film 24 is coated on the 
insulating layer 23 and subjected to patterning by exposure and 
development to open (or expose) portions of the insulating layer 23 
between the connecting layers 22 which are intended to be connected. That 
is, portions of the insulating layer 23 are masked in regions where 
adjacent connecting layers 22 are intended to remain isolated, and 
portions of the insulating layer 23 are opened (or exposed) in regions 
where adjacent connecting layers 22 are intended to be electrically 
connected. When the connecting layers 22 are not connected to each other, 
but are instead left independent, at least one of the circuit modules are 
defective or unnecessary in view of the circuit system. Though a laser 
beam or overcurrent is used for cutting off defective or unnecessary 
circuit modules in the background art, the method of the present invention 
requires no process of cutting. That is, referring to FIG. 2B, the 
patterned photoresist film 24 is used as a mask to enable the N type or P 
type ions to be selectively injected into the portions of the insulating 
layer 22 that are exposed, but not into the masked portions of the 
insulating layer 22. 
As shown in FIG. 2C, when heat treated, the N or P type ion injected 
insulating layer 23 becomes conductive, i.e., becomes connectors 23A, for 
electrically connecting adjacent connecting layers 22. 
FIGS. 3A.about.3C illustrate sectional views of a variable circuit 
connector corresponding to a method for forming that variable circuit 
connector in accordance with a second preferred embodiment of the present 
invention. In the second embodiment, no mask is used in injecting N type 
or P type ions selectively into the insulating layer 23. In fact, the 
process of forming an insulating layer on an entire surface inclusive of 
the connecting layers is the same with the first embodiment. 
Referring to FIG. 3A, a plurality of connecting layers 22 are formed on a 
wafer 21. As discussed with respect to FIG. 2A, the plurality of 
connecting layers 22, being conductors connected on terminals of circuit 
modules, include pads. Thus, the insulating layer 23 is formed on an 
entire surface of the wafer 21, inclusive of the plurality of connecting 
layers 22. The insulating layer 23 is formed of a material, such as 
silicon oxide or silicon. Portions of the insulating layer 23 are used, 
where appropriate, as connectors for electrically connecting adjacent 
connecting layers 22. 
Then, as shown in FIG. 3B, an ion beam with a narrow injection width is 
used to selectively inject ions into only desired portions of the 
insulating layer 23 between adjacent connecting layers that need to be 
connected. Though ions are injected into an entire surface using the 
photoresist as a mask in the first embodiment, an ion beam with a narrow 
injection width is used to selectively inject ions only into desired 
portions of the insulating layer 23 in the second embodiment. 
Accordingly, as shown in FIG. 3C, when heat treated, the ion injected 
insulating layer 23 becomes conductive, i.e., becomes connectors 23a, for 
electrically connecting adjacent connecting layers 22. 
Thus, by injecting N or P type ions into the insulating layer 23, the 
insulating layer 23 can be used to form connectors 23a between adjacent 
connecting layers 22 that are otherwise electrically separated. 
In conclusion, the formation of the connectors by selective injection of 
ions into a wafer having a plurality of circuit modules formed thereon 
allows a freedom in forming a circuit system. When it is desired to cut 
connected circuit modules, ions are selectively injected even in the 
cutting in the first and second embodiments. For example, the connectors 
electrically connecting the connecting layers 22 are formed by injecting P 
type ions into the insulating layer 23, upon injection of N type ions 
having a conductivity opposite to the P type ions into a required portion 
of the insulating layer 23, a depletion layer is formed to cut an 
electrical path. Thus, when the connector is neutralized by injecting ions 
having a conductivity opposite to the present conductivity of the 
connector, the electrical path is cut even though the path is not cut 
physically, and the connecting layers can therefore be isolated or at 
least separated. In addition, as an alternative, a connection between two 
adjacent connecting layers may be cut using a laser beam rather than 
injecting ions having a conductivity opposite to the conductivity of the 
connector. 
The method for forming a variable circuit connector of the present 
invention has various advantages over conventional connectors, including 
those noted hereinafter. 
First, because connection and cut-off of circuit modules are easy, a span 
of selection in formation of a system of circuit becomes greater. 
Second, as defects are reduced significantly compared to the case when a 
laser beam or an overcurrent is used, a production yield can be improved. 
While there have been illustrated and described what are at present 
considered to be preferred embodiments of the present invention, it will 
be understood by those skilled in the art that various changes and 
modifications may be made, and equivalents may be substituted for elements 
thereof without departing from the true scope of the present invention. In 
addition, many modifications may be made to adapt a particular situation 
or material to the teaching of the present invention without departing 
from the central scope thereof Therefor, it is intended that the present 
invention not be limited to the particular embodiment disclosed as the 
best mode contemplated for carrying out the present invention, but that 
the present invention includes all embodiments falling within the scope of 
the appended claims. 
The foregoing description and the drawings are regarded as including a 
variety of individually inventive concepts, some of which may lie 
partially or wholly outside the scope of some or all of the following 
claims. The fact that the applicant has chosen at the time of filing of 
the present application to restrict the claimed scope of protection in 
accordance with the following claims is not to be taken as a disclaimer of 
alternative inventive concepts that are included in the contents of the 
application and could be defined by claims differing in scope from the 
following claims, which different claims may be adopted subsequently 
during prosecution, for example, for the purposes of a continuation or 
divisional application.