Active solid-state devices (e.g. – transistors – solid-state diode – Encapsulated – With heat sink embedded in encapsulant
Reexamination Certificate
1999-06-29
2001-02-20
Williams, Alexander O. (Department: 2811)
Active solid-state devices (e.g., transistors, solid-state diode
Encapsulated
With heat sink embedded in encapsulant
C257S684000, C257S788000, C257S693000, C257S692000, C257S696000, C257S698000, C257S675000, C257S712000, C257S713000, C257S730000, C257S707000, C257S676000, C361S808000, C361S813000
Reexamination Certificate
active
06191494
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device and a method of producing the same.
2. Description of the Related Art
In recent years, semiconductor devices have been becoming smaller and more highly integrated. Along with this trend, more and more wrong operations and unstable characteristics are seen in a semiconductor device due to interference between regions having different functions.
In view of this, there has been an increasing demand for semiconductors in which no interference is caused between regions having different functions.
FIGS. 11A and 11B
are a sectional view and a perspective view of a conventional semiconductor device. A CSP (Chip Size Package) semiconductor device is shown in the figures.
In a conventional semiconductor device
81
shown in
FIG. 11A
, a semiconductor chip
82
is sealed in a resin package
83
. Signal terminals on the surface of the semiconductor chip
82
are electrically connected to mounting protrusions
85
protruding from the bottom surface of the resin package
83
by wires
84
.
The surfaces of the mounting protrusions are covered with metal films
86
, and the bottom surface of the semiconductor chip
82
is coated with an insulating adhesive
89
.
As shown in
FIG. 11B
, the semiconductor chip
82
is situated in the center of the semiconductor device
81
, and the metal films
86
(or the mounting protrusions
85
) are situated in the surrounding area of the semiconductor chip
82
. The metal films
86
are connected to the signal terminals of the semiconductor chip
82
by the wires
84
.
The signal terminals of the semiconductor chip
82
include terminals which input and output various signals, and a grounding terminal which serves as a reference potential.
Since semiconductor devices have been becoming smaller and more highly integrated, regions having various functions exist in a small area.
FIG. 12
is an enlarged sectional view of a part of the conventional semiconductor device, illustrating the problems in the prior art.
The semiconductor device
81
shown in
FIG. 12
has a PLL (Phase Locked Loop) circuit, for instance. The semiconductor chip
82
contains a plurality of functional regions including a first functional region
90
and a second functional region
91
. The functional regions are formed with a semiconductor substrate
87
as a base, and are divided by isolators
92
.
A wiring pattern
93
is formed on the surfaces of the first functional region
90
and the second functional region
91
, and a part of the wiring pattern
93
is connected to a grounding terminal
94
which is a reference potential. The grounding terminal
94
also serves to release small noise existing inside the semiconductor substrate
87
, and is formed on one of the isolators
92
.
The bottom surface of the semiconductor chip
82
, i.e., the bottom surface of the semiconductor substrate
87
, is coated with the insulating adhesive
89
.
Since the semiconductor device
81
is extremely small and highly integrated, the first functional region
90
and the second functional region
91
are disposed in an extremely small area, though they have different functions.
In the PLL circuit, frequency conversion is performed by a divider to generate a plurality of frequencies. For instance, the first functional region
90
operates on a frequency f
1
, while the second functional region
91
operates on a different frequency f
2
.
With such a structure, the frequency leaking from each region turns into noise that enters the neighboring functional region, as indicated by arrows in FIG.
12
. The noise often results in unstable characteristics or wrong operations.
The grounding terminal
94
disposed on the isolator
92
cannot release enough noise, because the first functional region
90
and the second functional region
91
are too close to each other. It is possible to release all noise by forming a plurality of grounding terminals at short intervals, but such a measure is not suitable for the highly-integrated small-size semiconductor device.
SUMMARY OF THE INVENTION
A general object of the present invention is to provide a semiconductor device and a method of producing the same in which the above disadvantages can be eliminated.
A more specific object of the present invention is to provide a highly integrated small semiconductor device in which adverse influence due to interference between different functional regions are prevented to achieve stable operations.
The above objects of the present invention are achieved by a semiconductor device which includes: a semiconductor chip: a resin package which seals the semiconductor chip; signal passages which guide signal terminals of the semiconductor chip outward from the resin package; a grounding metal film in contact with a bottom surface of the semiconductor chip; and a grounding passage which is connected to the grounding metal film and is guided outward from the resin package.
In this structure, the grounding metal film is in contact with the bottom surface of the semiconductor chip, so that unnecessary electric signals in the semiconductor chip are absorbed by the metal film and released outward. Thus, wrong operations due to interference between regions having different functions can be prevented.
The resin package of the semiconductor device has a plurality of mounting protrusions covered with metal films. The metal films on the mounting protrusions and the signal terminal of the semiconductor chip are connected by conductive wires to form the signal passages.
In this structure, there is no need to employ lead terminals extending outward from the semiconductor chip, and the mounting protrusions covered with the metal films serve as outer terminals immediately below the semiconductor chip. Thus, the semiconductor device can remain small in size, and unnecessary noise in the semiconductor chip can be released to the outside.
The above objects of the present invention are also achieved by a method of producing a semiconductor device in which a semiconductor chip is sealed in a resin package having a plurality of mounting protrusions so that signal terminals of the semiconductor chip are guided outward from the mounting protrusions. This method includes the steps of: attaching metal films onto the inner surfaces of concavities corresponding to the mounting protrusions, and to a semiconductor chip mounting surface surrounded by the concavities formed in a base; mounting the semiconductor chip onto the metal film surrounded by the concavities via a conductive adhesive; electrically connecting the signal terminals of the semiconductor chip to the metal films on the inner surfaces of the concavities by conductive wires; sealing the semiconductor chip and the conductive wires with resin; and detaching the base from the metal films on the inner surfaces of the concavities and the semiconductor chip mounting surface.
By this method, the grounding metal film can be formed at the time of the formation of the metal films on the mounting protrusions as the outer signal terminals. Thus, unnecessary noise in the semiconductor chip can be removed without complicating the production procedures.
The above and other objects and features of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A and 1B
are a sectional view and a bottom view of a semiconductor device of a first embodiment of the present invention;
FIGS. 2A
to
2
H are sectional views illustrating the production procedures of the first embodiment of the present invention;
FIG. 3
is a sectional view of mounted semiconductor devices of the first embodiment of the present invention;
FIGS. 4A and 4B
are a sectional view and a perspective view of a semiconductor device of a second embodiment of the present invention;
FIGS. 5A
to
5
H are sectional views illustrating the production procedures of the second embodiment of the present invention;
FIG. 6
is a partially enla
Fujisaki Fumitoshi
Kuramoto Syunichi
Maki Shinichiro
Matae Youichi
Ooyama Nobuo
Armstrong, Westerman Hattori, McLeland & Naughton
Fujitsu Limited
Williams Alexander O.
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