Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – Smart card package
Reexamination Certificate
2001-09-18
2002-11-26
Abraham, Fetsum (Department: 2826)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
Smart card package
C257S487000, C257S684000, C257S688000
Reexamination Certificate
active
06486541
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a reliable and low-cost semiconductor device, or more in particular to an IC (Integrated Circuit) card or a multichip module.
Conventional techniques for IC cards are described in “Information Processing Handbook”, first edition, pp. 302-304, compiled by Information Processing Society of Japan and published by Ohm, May 30, 1989. The same reference contains at pp. 242-244 also the description of techniques for packaging the IC card. The structure of IC cards is described in “IC Cards”, first edition, p. 33, compiled by The Institute of Electronics, Information and Communication Engineers and published by Ohm, May 25, 1990. Also, an IC card using a thin LSI is disclosed in JP-A-3-87299, Apr. 12, 1991.
FIGS. 1
,
2
and
3
are sectional views showing configurations of IC cards.
In
FIG. 1
showing a conventional IC card configuration, a chip
211
is bonded to a portion having a contact
210
, connected to a printed board
212
by a bonding wire
216
, and sealed by resin
215
. This module is embedded in a center core
213
of a hard material. The card surface is covered with an oversheet
209
and an oversheet
214
.
FIG. 2
shows another example of the prior art. A semiconductor chip is bonded to a substrate
207
by a adhesive agent
207
a
. Due to a thick silicon substrate
217
, however, the semiconductor is connected by being bonded to the substrate
207
by the adhesive
207
a
while absorbing the unevenness through a bonding wire
218
.
In the example shown in
FIG. 3
, an IC
6
has a great thickness of about 200 to 400 &mgr;m. This bulk IC
6
is bonded to a card board
8
by an adhesive
7
. Since the bulk IC is thick, however, the uneven wiring patterns on the IC and a substrate wiring
10
are connected by a wire bonding
9
. In this case, the bulk IC is easily subjected to bending stress and therefore stress relaxation is required. Also, in view of the limited sizes of the bulk IC, the structural requirement for improving the bending strength and the difficulty of reducing the number of wire-adhesive steps, the cost tends to increase.
JP-A-3-87299 (Apr. 12, 1991) has rendered well known an IC card configuration in which an IC module having a very thin LSI ground very thin leaving active elements is fitted in a surface recess.
This conventional configuration is shown in
FIG. 4. A
semiconductor element
204
is bonded on a substrate
207
by an adhesive
207
a
. A wiring
208
for connecting semiconductor elements is connected to a conductive pad
202
by way of a through hole
203
. This conductive pad
202
is further connected to the wiring on the substrate
207
by conductive paste
201
.
The problem of this configuration, as shown in
FIG. 4
, is that an adhesive layer is in direct contact with the lower surface of the semiconductor element
204
such as a transistor and ionic contaminants easily intrude the semiconductor element, thereby extremely deteriorating the reliability.
FIG. 5
is a diagram showing a problem specific to an IC card configured using a thin LSI disclosed in JP-A-3-87299 (Apr. 12, 1991). A thin LSI
41
mounted on a thick card substrate
42
is subjected to tensile or compressive stress on the front and reverse surfaces when the card substrate
42
is bent, thereby exerting a large stress on the LSI chip. The resulting thin structure and low mechanical strength under a large stress causes the IC to be easily broken by the stress. This gives a rise to a new problem of a considerably reduced reliability.
As described above, the IC card using a thin LSI layer including a thin semiconductor element is easily affected by ionic contaminants. Also, the thinness leads to a low mechanical strength. In the conventional IC cards using a bulk LSI, a bulk IC chip is attached on a thin, easy-to-bend card and wire-bonded. Therefore, the IC is easily broken and is low in reliability. Further, the increased number of packaging steps makes a cost reduction difficult.
SUMMARY OF THE INVENTION
The object of the present invention is to solve the above-mentioned problems of the prior art and to provide a semiconductor circuit, or more in particular a IC card or multichip module high in reliability and low in cost.
According to one aspect of the invention for solving the above-mentioned problems, there is provided a thin-film semiconductor device comprising at least a semiconductor element and a wiring, wherein a thin film of a protective insulating material for protecting the semiconductor element is formed on the lower surface thereof in contact with the semiconductor element, and the surface of the protective insulating film is bonded to other substrate.
According to another aspect of the invention for solving the above-mentioned problems, there is provided a semiconductor device wherein the thin-film semiconductor circuit includes a thin film of a semiconductor circuit formed on a silicon-on-insulator (hereinafter referred to as SOI) wafer, another substrate coupling the thin-film semiconductor circuit on the opposite side formed with the semiconductor circuit, and a hardenable conductive material for connecting the wiring prepared on the substrate and the wiring of the thin-film semiconductor circuit.
According to a third aspect of the invention for solving the above-mentioned problems, there is provided a semiconductor de vice wherein the thin-film semiconductor circuit is taken out of the main surface of the SOI wafer with the insulator layer inward thereof as a boundary.
According to another aspect of the invention for solving the above-mentioned problems, there is provided a semiconductor device wherein the thin-film semiconductor circuit and the other substrate are bonded by a rubber-like adhesive.
According to another aspect of the invention, there is provided a semiconductor device wherein the main surface is bonded to another support substrate, and then the SOI wafer substrate is ground or etched off.
According to still another aspect of the invention for solving the above-mentioned problems, there is provided a semiconductor device wherein the other substrate for coupling the thin-film semiconductor circuit is of a flexible card shape.
According to a further aspect of the invention for solving the above-mentioned problems, there is provided a semiconductor device wherein the other support substrate is flexible.
According to a still further aspect of the invention for solving the above-mentioned problems, there is provided a semiconductor device wherein the thin-film semiconductor circuit and the support substrate are bonded to each other by an adhesive separable under ultraviolet ray.
According to an even further aspect of the invention for solving the above-mentioned problems, there is provided a semiconductor device wherein the wiring by a liquid conductive material is a printed wiring with a rotary drum.
According to another aspect of the invention for solving the above-mentioned problems, there is provided a semiconductor device wherein the thin-film semiconductor circuit is located at the center of the same depth from the front and reverse surfaces of the other substrate.
According to still another aspect of the invention for solving the above-mentioned problems, there is provided a semiconductor device wherein the thin-film semiconductor circuit is bonded to one substrate and covered by being bonded to the other substrate of the same thickness.
According to a further aspect of the invention for solving the above-mentioned problems, there is provided a semiconductor device wherein the thin-film semiconductor circuit is formed with a wafer other than SOI.
According to a still further aspect of the invention for solving the above-mentioned problems, there is provided a card-like semiconductor device with a thin IC chip built in the card, wherein the thickness of the IC chip is 110 microns or less for the completed card thickness of 760 microns or more, 19 microns or less for the completed card thickness of 500 microns or more, and 4 microns or less for the completed card thickness
Tase Takashi
Usami Mitsuo
Abraham Fetsum
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
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