Semiconductor device

Details Semiconductor device Semiconductor device

2000-02-03

2003-03-18

Flynn, Nathan J. (Department: 2826)

Active solid-state devices (e.g., transistors, solid-state diode

Housing or package

C257S659000, C257S660000, C257S690000, C257S691000, C257S685000, C257S686000, C257S723000, C257S738000, C257S778000, C257S784000

Reexamination Certificate

active

06534847

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device (semiconductor chip) that achieves a desired function when connected to a semiconductor device (semiconductor chip) having a predetermined function so as to be functionally complemented or enhanced thereby, and the present invention relates also to a semiconductor device that is built by connecting together a plurality of semiconductor devices (semiconductor chips) having such a relationship with one another.
2. Description of the Prior Art
Some semiconductor devices achieve desired functions by the use of a plurality of semiconductor chips. A typical example is semiconductor devices that are built by superposing a plurality of semiconductor chips on one another and bonding them together and that thus have chip-on-chip structures.
In this type of semiconductor device, the internal circuit
111
of the mother chip
110
is often designed as an incomplete or insufficient circuit that does not achieve any practical function on its own; that is, this internal circuit
111
is often designed to achieve a desired practical function only when it is functionally complemented or enhanced by the internal circuit
121
of the daughter chip
120
. Specifically, for example, the output signal of the internal circuit
111
of the mother chip
110
is fed via the bump
130
to the internal circuit
121
of the daughter chip
2
, then the output signal of this internal circuit
121
is fed via the bump
131
back to the mother chip
110
, and only then this signal is fed to the external connection pad
121
as a practically significant signal.
The manufacturing process of a semiconductor device imperatively includes steps for functional checking of the semiconductor device, which involve pressing a test probe onto the pads provided on the surface of the semiconductor device. A semiconductor device composed of a plurality of semiconductor chips, if found defective after assembly, cannot be saved from being discarded totally, and therefore it is desirable to conduct functional checking of the individual semiconductor chips constituting such a semiconductor device before assembly.
However, as shown in
FIG. 4
, in a semiconductor device having a chip-on-chip structure that is built by bonding together a mother chip
110
and a daughter chip
120
with bumps
130
and
131
between them in such a way that the surface of the mother chip
110
faces the surface of the daughter chip
120
, the internal circuit
111
of the mother chip
110
is connected to the internal circuit
121
of the daughter chip
120
by way of those bumps
130
and
131
. External connection pads
112
for allowing input/output of signals from/to an external device are usually provided near the edge of the surface of the mother chip
110
so as to avoid the region thereon in which the daughter chip
120
is bonded to the mother chip
110
.
In this case, the internal circuit
111
of the mother chip
110
is designed as an incomplete or insufficient circuit, and is thus so designed that its output signal is fed only to the bump
130
for connection to the daughter chip
120
, and not to the external connection pad
112
on which the test probe is pressed. For this reason, the internal circuit
111
of the mother chip
110
cannot be subjected to functional checking by an ordinary method.
It is of course possible to conduct functional checking by pressing the test probe to the bump
130
. However, in general, such a bump
130
is provided in an inner region on the chip surface, and therefore it is not easy to press the test probe thereon accurately.
It is also possible to conduct functional checking by feeding the signal fed to the bump
130
further to another pad so that the signal can be monitored at that pad. However, this inevitably requires extra pads, and, where there are many signal lines to be monitored, requires even a larger chip size. Thus, this method is difficult to practice.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a semiconductor device that is functionally complemented or enhanced by another semiconductor device and that nevertheless allows easy functional checking of itself without provision of extra pads.
Another object of the present invention is to provide a semiconductor device that is built by combining together a plurality of semiconductor chips and that nevertheless allows easy functional checking of the individual semiconductor chips before they are assembled together.
To achieve the above objects, according to one aspect of the present invention, a semiconductor device is provided with a semiconductor substrate, a circuit formed on the semiconductor substrate so as to achieve a desired function by being connected to and thereby functionally complemented or enhanced by another semiconductor device having a predetermined function, a device-to-device connection portion formed on the semiconductor substrate so as to connect the circuit to the other semiconductor device having the predetermined function, an external connection portion formed on the semiconductor substrate so as to allow input/output of a signal from/to a device other than the other semiconductor device, and a switcher formed on the semiconductor substrate so as to switch between a state in which the circuit is disconnected from the external connection portion and a state in which the circuit is connected to the external connection portion.
In this configuration, even though the internal circuit of the semiconductor device is designed as an incomplete or insufficient circuit that achieves a practical function only when functionally complemented or enhanced by the other semiconductor device, and is thus of a kind that is not usually connected directly to the external connection portion, the switcher permits the internal circuit to be connected to the external connection portion. This makes it possible to conduct functional checking of the internal circuit itself independently of the other semiconductor device having the predetermined function, and in addition by the use of the external connection portion, which facilitates such functional checking.
According to another aspect of the present invention, a semiconductor device is provided with a first semiconductor chip having a first circuit, a second semiconductor chip having a second circuit that functionally complements or enhances the function of the first circuit, a device-to-device connection portion for connecting the first and second circuits to each other, an external connection portion formed on the first semiconductor chip so as to allow input/output of a signal from/to a device other than the second semiconductor chip, and a switching circuit formed on the first semiconductor chip so as to switch between a state in which the first circuit is disconnected from the external connection portion and a state in which the first circuit is connected to the external connection portion.
In this configuration, even though the first internal circuit formed on the first semiconductor chip is designed as a practically incomplete or insufficient circuit that needs to be functionally complemented or enhanced by the second internal circuit formed on the second semiconductor chip, and is thus of a kind that is not usually connected directly to the external connection portion, the switching circuit permits the first internal circuit to be connected to the external connection portion. This makes it possible to conduct functional checking of the first semiconductor chip independently without connecting it to the second semiconductor chip.


REFERENCES:
patent: 4697095 (1987-09-01), Fujii
patent: 4703483 (1987-10-01), Enomoto et al.
patent: 5097205 (1992-03-01), Toyoda
patent: 5977640 (1999-11-01), Bertin et al.
patent: 2002/0008309 (2002-01-01), Akiyama
patent: 486 829 (1992-05-01), None
patent: 61-73359 (1986-04-01), None
patent: 61-80846 (1986-04-01), None
patent: 1-307243 (1989-12-01), None
patent: 5-114693 (1993-05-01), None

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