Active solid-state devices (e.g. – transistors – solid-state diode – Gate arrays – With particular chip input/output means
Reexamination Certificate
2002-02-13
2004-09-14
Loke, Steven (Department: 2811)
Active solid-state devices (e.g., transistors, solid-state diode
Gate arrays
With particular chip input/output means
C257S206000, C257S207000, C257S208000, C257S691000
Reexamination Certificate
active
06791127
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to a semiconductor device, and more particularly, to a semiconductor device, which reduces unnecessary radiation.
In a semiconductor device such as an IC for an automobile, there is a problematic unnecessary radiation as a noise emitted from circuits. In order to reduce the unnecessary radiation, a new method to solve the problem is needed.
2. Description of the Related Art
A conventional semiconductor device has a bypass condenser (capacitor) as a means to reduce a noise emitted from a portion between a power supply and GND (ground) within an integrated circuit (IC). A structure having the bypass condenser can be achieved by two different formations as shown in FIG.
1
and FIG.
2
.
In
FIG. 1
, a bypass condenser
4
is placed between a semiconductor chip
1
and bonding pads (electrode terminals)
3
on a substrate
2
. The bypass condenser
4
reduces the noise by bypassing between one of the bonding pads
3
(Vcc) serving as a power supply terminal and one of the bonding pads
3
(Vss) serving as a ground terminal. Square areas in the central region of the semiconductor chip
1
are circuit blocks formed on the semiconductor chip
1
. The structure in
FIG. 1
has four circuit blocks A, B, C and D. For example, the bypass condenser
4
is attached to the mounting substrate
2
by being inserted into a slot formed on the surface of the substrate
2
. Electrode pads
1
a
on the semiconductor chip
1
and bonding pads
3
on the substrate
2
are connected through bonding wires
5
.
In
FIG. 2
, on the other hand, a bypass condenser
6
is provided within the semiconductor chip
1
. The bypass condenser
6
is a condenser (MOS capacitor) made by metal-oxide-film and is formable in a manufacturing process of the semiconductor chip
1
. The bypass conductor
6
reduces a noise by bypassing between a power supply line (Vcc line)
8
and a grounding line (Vss line)
9
that are connected to a circuit formed within the semiconductor chip
1
.
A radiation noise from a semiconductor device increases in proportion to an area of a current loop formed by a circuit being bypassed by a bypass condenser. In the conventional structure of
FIG. 1
, the noise is not effectively reduced because of a relatively large area of a current loop. As shown in
FIG. 1
, the bypass condenser
4
is connected between the power supply terminal and the grounding terminal on the substrate
2
. As indicated by an arrow in
FIG. 1
, the current loop includes a circuit, which extends from the power supply terminal to the grounding terminal. Thus, the area of the current loop is large. In addition, a manufacturing cost rises and the number of parts increases because a separate condenser is attached to the substrate
2
as the bypass condenser
4
.
In
FIG. 2
, an area of a current loop is smaller than that shown in
FIG. 1
because a condenser is formed within the semiconductor chip
1
so as to be a bypass condenser. The bypass condenser
6
formed within the semiconductor chip
1
is formed by a transistor having a MOS capacity. Because the MOS capacity cannot be included in a transistor region, the bypass condenser
6
is needed to be provided in a wiring region or a vacant region within the semiconductor chip
1
.
In order to form a bypass condenser having a comparatively large capacity within the semiconductor chip
1
, a space must be reserved for forming the bypass condenser
6
. Thus, there is a problem that a size of chip becomes large. Another problem is a cost increase because of a declining performance in processing speed caused by an increased line capacity or low yield.
In the case of forming a bypass condenser within a semiconductor chip, in chip design step, it is difficult to predict an effect of the bypass condenser. That is, an effective capacity of a bypass condenser and a circuit block, to which the bypass condenser is provided, can not be exactly predicted. The capacity of the bypass condenser to be inserted can be exactly determined by measuring the radiated noise so as to determine which circuit block radiates a large noise, after making a trial semiconductor chip. Accordingly, trial semiconductor chips must be produced several times while changing a position and a capacity of the bypass condenser. Thus, there is a problem in that a long time is required for developing a semiconductor device.
SUMMARY OF THE INVENTION
It is a general object of the present invention to provide an improved and a useful semiconductor device which solves the above-mentioned problems.
A more specific object of the present invention is to reduce a radiating noise effectively without increasing a plane area of a semiconductor chip.
In order to achieve the above-mentioned object, there is provided according to one aspect of the present invention a semiconductor device comprising:
a semiconductor chip having a circuit block, a power supply line and a ground line; and
a condenser chip in which a noise reduction condenser connected to said circuit block is formed,
wherein the condenser chip is stacked on said semiconductor chip.
According to the present invention, because the condenser chip is stacked on the semiconductor chip as a separate part, it is not necessary to provide a noise reduction condenser on the semiconductor chip, and it is also not necessary to provide the noise reduction condenser on the substrate on which the semiconductor chip is mounted. Thus, a condenser having a desired capacity can be connected to the semiconductor chip without increasing the plane area of the semiconductor device, so that the noise radiated from a circuit of the semiconductor chip can be reduced.
Additionally, in the semiconductor device according to the present invention, a plurality of circuit blocks may be formed in the semiconductor chip, and the condenser chip may have a plurality of condensers corresponding to the circuit blocks.
According to the present invention, because a plurality of condensers are formed in the condenser chip, the condensers can be connected to a plurality of circuit blocks individually.
Additionally, in the semiconductor device according to the present invention, a plurality of circuit blocks may be formed in the semiconductor chip, and a plurality of the condenser chips may be provided corresponding to the circuit blocks.
According to the present invention, because a plurality of the condenser chips are provided to be stacked on the semiconductor chip, the condensers can be connected to a plurality of circuit blocks individually.
Additionally, in the semiconductor device according to the present invention, the semiconductor chip may have a first power supply pad provided on a connecting line extending from one of the power supply line and the ground line to the circuit block; and
the condenser chip may have a second electrode pad connected the condenser, and the second electrode pad of the condenser chip may be electrically connected to the first electrode pad of the semiconductor chip through a bonding wire.
According to the present invention, the condenser chip can be easily stacked and mounted on the semiconductor chip by a conventional bonding wire.
Additionally, in the semiconductor device according to the present invention, the semiconductor chip may have a first power supply pad provided on a connecting line extending from one of the power supply line and the ground line to the circuit block; and
the condenser chip has a second electrode pad connected the condenser, and the condenser chip may be connected to the first electrode pad of the semiconductor chip by flip chip bonding.
According to the present invention, the condenser chip can be easily stacked and fixed on the semiconductor chip by a conventional flip chip bonding. Also, an increase in a thickness of the semiconductor device in a vertical direction can be reduced.
Additionally, in the semiconductor device according to the present invention, the noise reduction condenser of the condenser chip may be formed by a MOS capacity.
According to
Armstrong Kratz Quintos Hanson & Brooks, LLP
Loke Steven
Vu Quang
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