JP2970411B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly reliable and low cost IC (Integrated Circuit).
It relates <br/> the semiconductor equipment such as a card or a multichip module.

[0002]

2. Description of the Related Art Regarding the prior art of an IC card, see "Handbook of Information Processing" (published by Ohmsha, edited by Information Processing Society of Japan, first edition) (issued on May 30, 1989), No. 30.
2 to 304, and the technology for mounting an IC is described on pages 242 to 244 of the same book.
Regarding the structure of the C card, "IC Card" (edited by the Institute of Electronics, Information and Communication Engineers, Ohmsha, 1st edition) (1990)
May 25, 2013) Thin LSI described on page 33
Japanese Patent Application Laid-Open No. 3-87299 discloses an IC card using
There is a description in the publication.

FIGS. 2, 3 and 8 are cross-sectional views showing the structure of an IC card having a conventional structure.

FIG. 2 shows a sectional structure of a conventional IC card. After bonding the chip 211 to the portion having the contact 210, the printed circuit board 21 is bonded by the bonding wire 216.
2 and sealed with a resin 215. This module is embedded in a hard core core 213 and the card surface is covered by overseat 209 and overseat 214.

FIG. 3 shows another conventional example. Although the semiconductor chip is bonded to the substrate 207 by the adhesive 300, the bonding wires 21
8 absorbs the step and is connected to the substrate 207.

In the case of FIG. 8, the thickness of the IC 6 is 200
About 400 μm. The bulk IC 6 is bonded to the card substrate 8 with an adhesive 7,
Therefore, the wiring pattern on the stepped IC and the substrate wiring 10 are connected by the wire bonding 9. In this case, the bulk IC is weak against bending stress, and it is necessary to relax the stress. In addition, the size of the bulk IC is limited. However, there are problems such as high cost and high cost.

According to Japanese Patent Application Laid-Open No. 3-87299, an ultra-thin LS polished very thinly so that an active element portion remains.
The IC module with I is inserted into the concave part on the surface.
The structure of the C card is known. This example is shown in FIG. A semiconductor element 204 is bonded on a substrate 207 with an adhesive 300, and a wiring 208 connecting the semiconductor elements is connected to a conductive pad 202 through a through hole 203.
1 is connected to the wiring on the substrate 207. In such a structure, the semiconductor element 204 such as a transistor
Is directly in contact with the lower surface of the semiconductor device, and ionic contaminants and the like easily penetrate into the semiconductor element, and there is a problem that reliability is significantly reduced. FIG.
299 is a diagram showing a specific problem in an IC card having a structure using a thin LSI, and a thick card substrate 4
When the card substrate 42 is bent, a large stress is applied to the LSI chip when the card substrate 42 bends because a tensile or compressive stress acts on the front surface and the back surface, and the thin LSI 41 has a small mechanical strength. This indicates that a new problem that the reliability is remarkably reduced, such as the IC being easily broken by stress, occurs.

[0008]

As described above, an IC card using an LSI having a reduced thickness is susceptible to ionic contaminants because the semiconductor element is thin, and has low mechanical strength because it is thin. I using bulk LSI of conventional structure
In the C card, a bulk IC chip is attached to a thin card that is easy to bend and wire-bonded.
However, they are easily broken and lack reliability, and the mounting man-hour is large, which is not suitable for cost reduction.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art described above and to provide a highly reliable and low-cost I
Semiconductor equipment such as a C-card or multi-chip module
Is to provide.

[0010] The above object is to make the IC chip flexible.
On an IC card sandwiched between substrates,
The IC card has a thickness of 110 μm or less, and the IC card is
One side receives compressive stress when bent, the other side pulls
Placed on the neutral surface of the IC card to receive stress
The IC card is curved and bent.
IC card, and a first card having wiring
And the substrate, said first IC Ji joined with the bonding layer on a substrate
In an IC card and a-up, on the lower surface of the IC chip, an insulating material, contaminated protective film for preventing the ionic contaminants from the first substrate side is formed I
Achieved by C card .

[0011] It is another object of the present invention to provide a silicon-on-insulator wafer comprising a silicon substrate, an insulating film provided on the silicon substrate, and a single crystal semiconductor thin film provided on the insulating film. Forming a semiconductor device, etching the back surface of the wafer to expose the insulating film, forming a contamination protection film on the insulating film, cutting out the plurality of semiconductor devices, and forming a plurality of Forming a thin film semiconductor chip, attaching the thin film semiconductor chip to a second substrate having wiring, and connecting the thin film semiconductor chip and the wiring of the second substrate by printing. The present invention is achieved by a method for manufacturing a semiconductor device having the above.

The above object can be attained more effectively by forming the contamination prevention film by a silicon nitride film.

[0013]

[Function] A thinned IC chip is placed between substrates.
By arranging it, mechanical
The stress is reduced, and the reliability of the IC card is improved. The thin <br/> have semiconductor elements are shorted with a placing a protective insulating film on the rear surface,
Since those-holding Mamorumaku prevents back surface from ionic contaminant intrusion closest semiconductor element to the outside, by which it is possible to improve reliability, generally an inexpensive organic solvents are often ionic impurities thin LSI It is possible to provide a durable IC card even if it is bonded to a substrate using the IC card.

When a silicon nitride film is used as the protective insulating film, the film has a large coefficient of thermal expansion.
Curling due to the internal residual stress of the SI can be suppressed, and it is possible to contribute to improvement of the reliability of the IC card.

By using an SOI wafer, the thin insulator IC can be formed extremely thinly and uniformly with good reproducibility by using the inner insulator layer as a processing stopper layer. The thinned IC has a thickness of 5 to 10 μm,
Such a thin IC is resistant to bending, and if it is bonded to a thin substrate such as an IC card with a flexible adhesive, the card is resistant to bending and high reliability can be achieved.

Further, since the thin film IC alone is easily broken, the thin film IC can be manufactured with high stability by attaching the thin film IC to the supporting substrate in advance. If the bonding to the support substrate is performed by using an ultraviolet-peelable adhesive, the support substrate can be reliably removed at a low temperature. Since the thin-film IC attached to the card is thin, wiring between the substrate and the IC can be made with a conductive paste, making it more suitable for mass production and less material cost than conventional wire bonding using gold wires. Inexpensive, flat and thin IC cards can be produced.

The method described above can be applied not only to an IC card but also to the mounting of similar ICs, and can also be applied to a multi-chip mounting.

Next, considering the cross section of a flat plate of an IC card, the curved surface is elongated and the rear surface is shrunk. At this time, the central portion of the cross section of the IC card is in a state where there is little stress without contraction. If a thin IC chip exists in this portion, the stress applied to this IC chip can be reduced. At this time, it is sufficient that the IC chip is thin, but if the card is thick, the critical curvature becomes large due to the rigidity of the card, and it becomes difficult to bend. Therefore, the IC chip may be thick to some extent. Conversely, when the thickness of the IC card is thin, the thickness of the IC chip must be reduced in order to ease the bending of the IC chip in order to ease the stress. In order to reduce the thickness of an IC, the thinner the film, the more precise a device is required. Therefore, changing the thickness of the required IC chip according to the thickness of the IC card is necessary to secure the economic viewpoint and the required reliability. This is extremely significant. Thus, it has been found that the thickness of the IC card and the IC chip have a correlation, and when the thickness of the completed card is 760 microns or more, the thickness of the IC chip is 110 microns or less. Yes, when the thickness of the completed card is 500 microns or more, the thickness of the IC chip is 19 microns or less, and when the thickness of the completed card is 250 microns or more, the I
By making the thickness of the C chip 4 μm or less, an IC card with high economical reliability can be obtained.

Here, the thin film semiconductor circuit is formed of the SO
After taking out from the main surface side with the insulator layer of the inner layer of the I wafer as a boundary, it can be bonded to the other substrate, and specifically, the main surface side of the semiconductor circuit formed by the SOI wafer can be After bonding to the supporting substrate,
It can be formed by removing the substrate of the OI wafer by grinding or etching.

The bonding of the thin film semiconductor circuit to the other substrate is desirably performed with a rubber-like adhesive.

Further, it is desirable that the other substrate for bonding the thin film semiconductor circuit is a flexible card-shaped substrate.

It is desirable that the other supporting substrate is also a flexible supporting substrate.

Further, the bonding between the thin film semiconductor circuit and the other supporting substrate is performed by using an adhesive whose adhesive strength is reduced by ultraviolet rays (hereinafter, abbreviated as an ultraviolet peeling adhesive). Of the supporting substrate can be easily performed.

It is effective that the liquid conductive material is coated on the wiring by printing using a rotating drum.

Further, the thin-film semiconductor circuit is a thin-film semiconductor circuit located at the center of the same depth from the front surface and the back surface of the other substrate. More specifically, the thin-film semiconductor circuit is formed on the other substrate. An IC card can be easily manufactured by bonding to one substrate and covering the substrate with another substrate having the same thickness.

In the above description, an example in which a thin film semiconductor circuit formed on an SOI wafer is used has been described. Although the controllability of the film thickness is deteriorated, the manufacturing cost is reduced.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a semiconductor device having the structure of the present invention will be described in detail with reference to embodiments.

(Embodiment 1) FIG. 1 is a sectional view of a principal part of a semiconductor device showing an embodiment of the present invention. In FIG. 1, the conductive paste layer 201 is
3 and electrically connected to a pad 202 electrically connected to the outside of the chip. Wiring 2
Reference numeral 08 connects the semiconductor elements 204 to form a circuit. The semiconductor element 204 is bonded to the substrate 207 with the adhesive 300 via the silicon nitride film 206.
The silicon nitride film 206 is provided on the lower surface of the silicon oxide film 205. The silicon oxide film 205 on the lower surface of the semiconductor element 204 electrically isolates the element. Since this semiconductor element is formed using a bonded silicon insulator wafer (SOI wafer), it is formed extremely thin, and at the same time, the silicon oxide film 205 is formed of SO
It is also the insulator layer of the inner layer of the I wafer. The silicon oxide film alone does not have a function of blocking Na, H ₂ , H ₂ O, and the like, and the semiconductor element is contaminated with ionic substances, resulting in insufficient long-term stable operation. In particular, when the silicon oxide film is made thin and the lower surface and the outside of the semiconductor element approach each other to within 10 microns, the diffusion distance of impurities becomes within the LSI operating temperature, and the reliability of the LSI becomes a major issue. Here, if the silicon oxide film is made thicker, the process in the wafer becomes 100
If the temperature is 0 ° C. or higher, the wafer bends and misalignment occurs, so that fine processing becomes impossible.

Here, the silicon nitride film is formed after the LSI is thinned. As a passivation film, a silicon nitride film is excellent in chemical, physical and electrical properties, and particularly excellent in non-permeability of Na, H ₂ , and H ₂ O, so that it is excellent in protection of thinned LSI semiconductor elements. It has the effect. Here, the thickness of the silicon nitride film is 1 μm to 0.0 μm.
A range of 1 μm is suitable. If the thickness is 1 μm or more, the silicon nitride film is cracked and cannot be used. Also,
If it is less than 0.01 μm, contamination with impurity ions such as Na cannot be sufficiently prevented in practical use.

FIG. 6 shows a process of manufacturing the semiconductor device shown in FIG.
Shown in First, as shown in FIG. 6A, on a main surface of an SOI wafer having a silicon oxide film 205 on a silicon substrate 217, a semiconductor element 204 and a wiring 208 interconnecting them, and an upper part of the wiring 208 Then, a semiconductor device having pad 202 via through hole 203 is formed.

Next, as shown in FIG. 6B, only the silicon substrate 217 is etched by potassium hydroxide or hydrazine which etches only silicon. Further, as shown in FIG. 6C, a silicon nitride film is formed on the back surface side of the silicon oxide film 205. Thereafter, as shown in FIG. 1, the LSI formed in the thin film is bonded with an adhesive 300 and then connected to a substrate using a conductive paste 201, thereby completing a semiconductor device.

Since the thickness of the thin film LSI is reduced to the order of 1 to 10 microns, after bonding to the substrate, the step with the substrate is small, and connection can be made with a liquid material such as paste or ink. As a result, the connection can be made flat at an extremely low height, and an optimum shape for an IC card can be obtained. In addition, since the conductive paste is as thin as about 10 μm and has high flexibility, it can have a characteristic of being resistant to bending and a difference in thermal expansion.

(Embodiment 2) FIG. 5 shows another embodiment of the present invention. In FIG. 5, the conductive paste 201 is the wiring 2
The pad is electrically connected to the outside of the chip by being connected to the pad 202 electrically connected through the through hole 203 on the chip 08. The wiring 208 connects the semiconductor elements 204 to form a circuit. The semiconductor element 204 is bonded to the substrate 207 with the adhesive 300 via the silicon nitride film 206. In this figure, a silicon nitride film is used instead of the silicon oxide film of FIG. In this case LS
As a means for reducing I, although not limited, a structure is adopted in which the lower surface of the semiconductor element is protected with a silicon nitride film after the thickness is reduced. This silicon nitride film has the effect of adjusting the coefficient of thermal expansion to prevent the thinned LSI from curling due to internal residual stress.

(Embodiment 3) FIG. 7 is a sectional view showing the structure of an embodiment of the semiconductor device of the present invention, in which a thin film IC 1 is bonded to a card substrate 2 with an adhesive 3. Here, the thickness of the thin film IC varies depending on the number of layers of transistors and wirings, but is about 5 to 10 μm. Because of such a thinness, the conductive ink 4 enables the wiring connection between the substrate wiring 5 and the wiring pattern on the thin film IC 1. A thin film IC is easy to bend unlike a bulk IC, and thus is suitable for bonding to a plastic substrate such as a card substrate which is easily bent. The adhesive for bonding the thin film IC 1 and the card substrate 2 is preferably a rubber-like or flexible adhesive.
The bending stress on C can be reduced.

(Embodiment 4) FIG. 9 is a process chart showing a procedure for manufacturing an IC card which is an embodiment of a semiconductor device having the structure of the present invention. First, a thin film IC on an SOI wafer
(LSI) is created (step 101). Next, the silicon substrate on the back surface is removed by etching using potassium hydroxide (step 102). In this case, since the silicon oxide film as the inner layer of the SOI wafer cannot be removed with potassium hydroxide, a thin film IC can be formed in a self-aligned manner (step 103). Also, at this time, since the thin film IC is curled due to the internal stress when the thin film IC is used alone, the main surface side of the SOI wafer is bonded to the supporting substrate in advance with an adhesive. FIG. 10 is a cross-sectional view showing a state where the silicon substrate of the SOI wafer is removed. Here, 11 is a support substrate,
12 denotes an adhesive, 13 denotes a thin film IC, and 14 denotes an inner insulator layer of the SOI wafer. Subsequently, the thin-film IC is attached and adhered to the card substrate (step 104), and then the support substrate is removed. Finally, using a printing technique, the thin-film IC and the wiring terminals on the card substrate are connected by printed wiring (step 104). 104). In this manner, the silicon oxide film on the inner layer of the LSI using the silicon-on-insulator wafer is used as a boundary layer, and the thin film is uniformly and reproducibly thinned over a wide area by etching.

FIG. 11 is a sectional view showing a state immediately after the thin film IC with the supporting substrate is bonded to the card substrate.
Is applied to the transparent support substrate 18 with the ultraviolet peeling adhesive 19,
The state in which the rubber-like adhesive 17 adheres to the card substrate 15 is shown. Here, the UV-peelable adhesive is a tacky acrylic resin-based adhesive which has a property that the gel is hardened by ultraviolet rays and has a property that the peelability is generated. It is effective in peeling. Further, the rubber-like adhesive 17 absorbs stress even when the card substrate bends with respect to the thin film IC, and the thin film IC
Stress concentration on the substrate can be reduced. Also, thin film IC
The stress concentration due to the difference in the coefficient of thermal expansion between the thin film IC and the card substrate can be reduced, so that the thin film IC can be bonded to the card substrate with high reliability.

FIG. 12 is a sectional view showing a state after the support substrate 18 is removed from FIG. The support substrate 18 includes a thin film IC 16 (20 in FIG. 12) and a card substrate 15 (FIG. 12).
In this case, it is unnecessary if it is adhered to 21), so it is removed. However, if an ultraviolet-peeling adhesive is used for the adhesion, the thin film IC is firmly adhered until the ultraviolet light is irradiated, and it is supported after the ultraviolet light is irradiated. If the substrate is caught and peeled off, it can be easily removed. Thus, an extremely thin film IC
Can be stably bonded to the card substrate.

FIG. 13 shows that the thin film IC 22 is
FIG. 4 is a cross-sectional view showing a configuration in a state where wiring is performed between the thin film IC and the card substrate 25 after bonding to the thin film IC. Since the thin film IC 22 has a thickness of 5 to 10 μm and the adhesive for bonding the thin film IC to the card substrate 25 has a thickness of about 20 to 30 μm,
The step between the upper surface of the card substrate 25 and the upper surface of the thin-film IC 22 is extremely small as compared with the conventional case where a bulk IC is bonded to the card substrate. Therefore, it is possible to connect the thin-film IC and the wiring 23 on the card substrate by the wiring 24 made of conductive ink by the conventional printing technique, and a large number of connections can be made in a very short time. . As a result, mass production and cost reduction of IC cards can be achieved.

FIG. 14 shows an example in which the structure of the present invention is mounted on a multichip substrate. After bonding the thin film IC 26 prepared by the above-described procedure to the multi-chip substrate 27, the conductive ink 29 is printed by a printing technique.
Is connected to the wiring 28 on the multi-chip substrate 27, a low-cost multi-chip module can be obtained.

The material of the conductive ink is not particularly limited as long as it is in a liquid state.

FIG. 15 shows a semiconductor device (IC card) of the present invention.
FIG. 1 is a view schematically showing a printing apparatus used for obtaining a print job.
The IC card of the present invention is characterized in that the connection between the IC and the card substrate can be formed in a large amount in a short time.
The ink 32 of the wiring pattern is transferred to
Is transferred onto the thin film IC mounting substrate (before printing) 30 on the belt 34 passing through the side surface of the rotating drum rotated at a high speed, thereby discharging the thin film IC mounting substrate (after printing) 33. Can be realized.

FIG. 16 is a sectional view showing an example of a state in which a thin film IC is embedded in an IC card. The thin film IC 35
To withstand the bending of the card board 36 well,
The card board 36 is placed on the neutral plane. This is because, when the card substrate is bent, tensile or compressive stress acts on the front and back surfaces. However, if the thin film IC is on the neutral surface, such a force does not act, and it is resistant to bending and has high reliability. Can be achieved. Here, one place to put the LSI is IC from the ideal neutral side.
By setting the thickness within a range of ± 5% of the thickness of the card, industrial productivity and reliability of the card can be secured.

FIG. 17 is a view for explaining a procedure for obtaining the structure of FIG.
By pasting C35 and then pasting a card substrate II 37 having the same thickness as the card substrate I, the thin film IC can be easily buried in the neutral surface of the IC card as shown in FIG. A plurality of such thin film ICs can be placed at any place on the card substrate.

(Embodiment 5) FIG. 19 shows an embodiment of the present invention. This figure is a cross-sectional view of the IC card and shows a state where the IC card is bent by bending stress. Since the thin-film LSI chip 104 is located exactly on the center line 200 of the cross section of the card and is extremely strong in bending, that is, on the neutral surface of the card,
A stress is not applied to the I chip 104.
The thin-film LSI chip also bends and curves the IC card, but the stress is reduced because the thin-film LSI chip is thin.

FIG. 20 shows a state in which the LSI chip 105 is bent. R shown in FIG. 20 is the center 10 of the curvature.
The radius of curvature from 7 to the center line 106 in the thickness direction of the LSI chip 105, and t indicates half the thickness of the LSI.
According to Navier's theorem, the stress σ on the LSI surface is expressed by E × t / R. Here, E may be considered as the Young's modulus of the LSI.
Since the surface of the LSI is a silicon oxide film, E is equivalent to the Young's modulus of the silicon oxide film. From this equation,
It can be seen that the stress on the LSI surface is proportional to the thickness of the LSI and inversely proportional to the radius of curvature. It is considered that the LSI breaks due to bending when the surface stress exceeds the mechanical strength of the LSI. When there is no bending, the surface stress is zero because R is infinite, and when the bending progresses and R decreases, the stress increases steadily and eventually destroys the LSI. By the way, since the surface stress decreases as the thickness of the LSI decreases with respect to the bending having the same radius of curvature, the LSI becomes sufficiently strong in bending if the thickness is reduced so as not to reach the limit of mechanical destruction. . However, if the LSI exists alone in a thin state, it is difficult to handle. If the thin LSI is sandwiched between materials such as plastic and metal on both sides, the handling becomes easy and the strength is increased at the same time. it can. At this time, it is necessary that the thin-film LSI chip be located on the neutral surface of the sandwiched material. For example, in the case of an IC card, the thin-film LSI chip is viewed from the cross section of the card substrate as shown in FIG. It is necessary to be on the neutral plane. By doing so, the neutral surface of the LSI, that is, the surface where the stress is zero even when bent and the neutral surface of the card coincide, and even if the card is bent, the same effect as the thin-film LSI chip bent alone is obtained. Can be expected.

Next, an embodiment in which a card is created by using a thinned LSI will be described with reference to FIGS. 21 and 22. First, as shown in FIG.
8 begins with the formation of the metallized pattern 109. The metallized pattern 109 is formed by etching a copper thin film or using a conductive paste or ink. In this state, the thin-film LSI chip 110 is attached as shown in FIG. The material to be stuck may be an ordinary adhesive. FIG. 22 (a) shows the conductive paste 111
After connecting the thin-film LSI chip 110, FIG.
FIG. 3B shows a state in which the upper card substrate 112 is bonded as shown in FIG. At this time, the lower card substrate 8 and the upper card substrate 12 need to have the same thickness. By doing so, the thin-film LSI chip is on the neutral surface of the completed card, and is in a state strong against bending stress. Compared with the conventional card, this card can be made by integrating the card substrate and the LSI. Also, since it is connected by conductive paste, wire bonding is not required, and low cost, thin and flexible IC card is used. Can be created.

FIG. 23 is a top view of the IC card of the present invention. The thin-film LSI chip 11 on the IC card plane 113
4 and a conductor pattern 115. A coil is shown as an example of the conductor pattern. The coil has a role of receiving an electromagnetic wave from outside the IC card, generating an induced electromotive force, and supplying energy to the thin-film LSI chip.
The coil pattern and the thin-film LSI chip are connected by a conductive paste. The coil also has a function of receiving information data from the outside of the IC card and transferring the data to the thin-film LSI chip, and transmitting the data to the outside of the IC card as data electromagnetic waves from the thin-film LSI chip. When the thin film LSI chip has a bending moment at a corner of the card which is smaller than the center of the card when viewed from the plane of the card, the radius of curvature can be reduced, and an IC card more resistant to bending can be obtained. By using such a card, a contactless and highly reliable I
C cards can be created. Among the conventional IC cards, those of the contact type, which have electrodes on the surface of the card, have a drawback of causing contact failure and being susceptible to static electricity. However, the structure of the present invention does not prevent application to a conventional contact-type IC card.

FIG. 24 shows an IC card in which the thin-film LSI 116 is structured so as to be surrounded by a flexible adhesive 119 such as silicone. With such a structure, the adhesive 119 also serves to bond the upper card substrate 117 and the lower card substrate 118,
Since the thin-film LSI chip is surrounded by a soft rubber-like material, it is possible to make it difficult to apply stress to the surface of the LSI, and to make the IC card more resistant to bending. Also, even if the card substrate is deformed due to a shocking local force, the bonding layer 119 can play a role of buffering the shocking force, thereby preventing the application of stress to the thin-film LSI chip. .

FIG. 25 shows the stress on the surface of the LSI using the thickness of the card as a parameter. Thin film LSI
The stress on the surface of the thin-film LSI can be determined by taking the ratio of the thickness of the LSI to the thickness of the card by setting the stress on the neutral surface of the card substrate. The stress on the surface of the LSI is greatly related to the degree of bending of the card. The degree to which the card bends varies greatly depending on the thickness and material of the card, the applied force and the position of the card, etc., but cannot be determined in a straightforward manner. Here, the position where the LSI is placed is considered to be the position of the neutral surface of the card. Consider vinyl chloride used in general magnetic cards and IC cards. PET material (a heat-resistant crystalline thermoplastic, polyethylene terephthalate) has the property of being harder and more difficult to bend.
It can be considered that a rather general case is considered. Here, the radius of curvature that determines the bending depends on the bending moment applied to the card, but is assumed to be applied to the limit at which the card can be bent. Here, according to simple actual measurement, when the thickness of the card is 0.76 mm with vinyl chloride, the radius of curvature is 50 mm at the center of the card. At this time, if the LSI has the same thickness as the card, the stress on the surface of the LSI is 8E10 × 0.38 / 50 (Pa) from the stress formula, which is calculated to be 600 MPa. Considering that the surface of the LSI is mainly composed of a silicon oxide film layer, it can be considered to be a physical property of glass. Therefore, the Young's modulus used the value of glass from a scientific chronological table.

Next, regarding the relationship between the radius of curvature and the thickness of the card, the moment of inertia of the card is related at this time. The radius of curvature R is given by E × I / M, where E is the Young's modulus of the card, I is the moment of inertia, and M is the bending moment. Since the moment of inertia of the card is proportional to the cube of the thickness of the card, a characteristic curve of the radius of curvature as shown in FIG. 27 is obtained. From this characteristic, when the ratio of the thickness of the LSI to the thickness of the card is 1.0, the stress on the surface of the LSI is obtained. As shown in FIG.
Surface stress can be determined. That is, when the thickness of the card is 0.5 mm, it is 2.4 GPa, and when the thickness of the card is 0.25 mm, it is 5.4 GPa. In this state, the LSI is easily destroyed.
Is made into a thin film and inserted into the card between the neutral surfaces.
That is, FIG. 25 plots the stress on the thinned LSI surface using the ratio of the LSI thickness to the card thickness as a parameter. FIG. 26 is an enlarged view of this figure, in which the ratio of the thickness of the LSI to the thickness of the card from 0 to 0.16 is enlarged. The area that can withstand the bending of the LSI is considered to be the same as the breaking strength of the glass, and is set to 90 MPa from the scientific chronological table. Therefore, the required thickness of the thin-film LSI at each thickness of the card can be obtained, and the limit for reducing the thickness of the LSI can be obtained. That is, when the card is 0.76 mm, the thickness of the LSI must be 110 μm or less, and when the card is 0.5 mm, the thickness must be 19 μm or less. When the card thickness is 0.25 mm, the thickness must be 4 μm or less. . Of course, the reliability is greatly improved when the LSI is made as thin as possible.

[0051]

As described above, by using a semiconductor device according to the present invention as a device of the present invention, the problems of the prior art can be solved, and a highly reliable and low-cost IC card can be obtained. Or a multi-chip module could be provided. That is, the thin semiconductor element improves reliability because the protective insulating film prevents the intrusion of the ionic contamination source from the rear surface of the semiconductor element closest to the outside by the above-described means by providing the protective insulating film on the back surface. This makes it possible to manufacture an IC card that is durable even when a thin LSI is bonded to a substrate by using an inexpensive organic adhesive generally containing a large amount of ionic impurities.

When a silicon nitride film is used as the protective insulating film, the film has a large coefficient of thermal expansion.
Curling due to the internal residual stress of the SI can be suppressed, and it is possible to contribute to improvement of the reliability of the IC card.

By using an SOI wafer, the thin insulator IC can be formed extremely thinly and uniformly with high reproducibility, with the inner insulator layer serving as a stopper layer for processing. The thinned IC has a thickness of 5 to 10 μm,
Such a thin IC is resistant to bending, and if it is bonded to a thin substrate such as an IC card with a flexible adhesive, the card is resistant to bending and high reliability can be achieved.

Further, since the thin film IC alone is apt to be broken, the thin film IC can be manufactured with good stability by attaching the thin film IC to the supporting substrate in advance. If the bonding to the support substrate is performed by using an ultraviolet-peelable adhesive, the support substrate can be reliably removed at a low temperature. Since the thin film IC attached to the card is thin, it is possible to wire between the substrate and the IC with printing ink,
A low-cost flat IC card can be manufactured.

The method described above can be applied not only to an IC card but also to the mounting of a similar IC, and can also be applied to a multi-chip mounting.

Next, considering the cross section of the flat plate of the IC card, the curved front surface is elongated and the rear surface is shrunk. At this time, the central portion of the cross section of the IC card is in a state where there is little stress without contraction. If a thin IC chip exists in this portion, the stress applied to this IC chip can be reduced. At this time, it is sufficient that the IC chip is thin, but if the card is thick, the critical curvature becomes large due to the rigidity of the card, and it becomes difficult to bend. Therefore, the IC chip may be thick to some extent. Conversely, when the thickness of the IC card is thin, the thickness of the IC chip must be reduced in order to ease the bending of the IC chip in order to ease the stress. In order to reduce the thickness of an IC, the thinner the film, the more precise a device is required. Therefore, changing the thickness of the required IC chip according to the thickness of the IC card is necessary to secure the economic viewpoint and the required reliability. This is extremely significant. Thus, it has been found that the thickness of the IC card and the IC chip have a correlation, and when the thickness of the completed card is 760 microns or more, the thickness of the IC chip is 110 microns or less. Yes, when the thickness of the completed card is 500 microns or more, the thickness of the IC chip is 19 microns or less, and when the thickness of the completed card is 250 microns or more, the I
By making the thickness of the C chip 4 μm or less, an IC card with high economical reliability can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a semiconductor device according to the present invention.

FIG. 2 is a sectional view of a main part of a conventional IC card.

FIG. 3 is a sectional view of a main part of another conventional IC card.

FIG. 4 is a sectional view of a main part of another conventional IC card.

FIG. 5 is a sectional view of a main part of another semiconductor device according to the present invention.

FIG. 6 is a device cross-sectional view showing a manufacturing step of the semiconductor device according to the present invention.

FIG. 7 is a sectional view of a main part of the IC card according to the present invention.

FIG. 8 is a sectional view of a main part of another conventional IC card.

FIG. 9 is a process diagram showing a procedure for manufacturing an IC card which is an embodiment of the semiconductor device according to the present invention.

FIG. 10 is a cross-sectional view illustrating a thin-film IC formed using an SOI wafer.

FIG. 11 is a sectional view showing a state in which the thin-film IC with a support substrate is bonded to a card substrate.

FIG. 12 is a cross-sectional view showing a state in which a support substrate has been removed by ultraviolet irradiation.

FIG. 13 is a cross-sectional view showing a state in which the thin-film IC and the wiring of the substrate are connected with conductive ink.

FIG. 14 is a sectional view showing a state in which the configuration of the present invention is used in a multichip module.

FIG. 15 is a cross-sectional view of an apparatus that prints wiring using conductive ink.

FIG. 16 is a sectional view showing a state in which a thin film IC is embedded in a card substrate.

FIG. 17 is a cross-sectional view of the card board for explaining a procedure for obtaining the structure of FIG. 16;

FIG. 18 is a sectional view showing a state in which an IC card having a conventional structure and a thick substrate is bent.

FIG. 19 is an essential part cross-sectional view of an IC card showing one embodiment of the present invention.

FIG. 20 is an essential part cross-sectional view of the IC card for illustrating the principle of the present invention;

FIG. 21 is an essential part cross sectional view showing the manufacturing process of one IC card according to the embodiment of the present invention;

FIG. 22 is an essential part cross sectional view showing the manufacturing process of another IC card according to the embodiment of the present invention;

FIG. 23 is a plan view of an IC card showing one embodiment of the present invention.

FIG. 24 is a cross-sectional view of an IC card showing one embodiment of the present invention.

FIG. 25 shows the LSI with respect to the thickness ratio between the LSI and the card.
The figure which showed the relationship of the stress of a surface.

FIG. 26 shows the LSI with respect to the thickness ratio between the LSI and the card.
The figure which showed the relationship of the stress of a surface.

FIG. 27 shows the radius of curvature and LS with respect to the thickness of the IC card.
The figure which shows the relationship of the stress of I surface.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Thin-film IC, 2 ... Card board, 3 ... Adhesive, 4 ... Conductive ink, 5 ... Board wiring, 6 ... Bulk IC, 7 ... Adhesive, 8 ... Card board, 9 ... Wire bonding, 10 ...
Substrate wiring, 11 support substrate, 12 adhesive, 13 thin film IC, 14 inner insulator layer of SOI wafer, 1
5: Card substrate, 16: Thin film IC, 17: Rubber adhesive, 18: Support substrate, 19: UV peelable adhesive, 20
... Thin film IC, 21 ... Card substrate, 22 ... Thin film IC, 23
... wiring on a card substrate, 24 ... wiring with conductive ink, 25 ... card substrate, 26 ... thin-film IC, 27 ... multi-chip substrate, 28 ... wiring on a multi-chip substrate, 2
9: conductive ink, 30: IC mounting board (before printing), 3
1 ... rotating drum, 32 ... wiring pattern ink, 33 ...
IC mounting substrate (after printing), 34 ... belt, 35 ... thin film I
C, 36: card board, 37: center of card board, 38
... Thin film IC, 39 ... Card board I, 40 ... Card board I
I, 41: bonded IC, 42: thick substrate, 101:
IC card cross section, 102 ... upper card board, 200 ...
Center line of the card, 103 ... Lower card board, 104 ...
Thin film LSI chip, 105 LSI chip, 106 center line, 107 center of curvature, 108 lower card substrate, 109 metallized pattern, 110 thin film LSI
Chip, 111: conductive paste, 112: upper card board, 113: IC card plane, 114: thin-film LSI
Chip, 115: conductor pattern, 116: thin-film LSI,
117: upper card substrate, 118: lower card substrate, 119: flexible adhesive, 201: conductive paste, 202: pad, 203: through hole, 20
4 semiconductor device, 205 silicon oxide film, 206 silicon nitride film, 207 substrate, 300 adhesive, 208
... wiring, 209 ... oversheet, 210 ... contacts,
211: IC chip, 212: Printed circuit board, 213:
Center core, 214: over sheet, 215: resin, 2
16 bonding wire, 217 silicon substrate, 2
18. Bonding wire.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 23/12 B42D 15/10 521

Claims (23)

(57) [Claims] 1. An IC card in which an IC chip is sandwiched between flexible substrates, wherein the IC chip has a thickness of 110 μm or less, and when the IC card is bent, one surface receives a compressive stress and the other surface receives a compressive stress. Neutral of the IC card to receive tensile stress
An IC card arranged on a surface , wherein the IC card is curved and bent. 2. The IC card according to claim 1, wherein said IC chip is disposed in a region deviated from the center of said IC card when viewed in plan.
card. 3. The IC card according to claim 1, wherein said flexible substrate is made of vinyl chloride or polyethylene terephthalate. 4. The IC card according to claim 1, wherein the IC chip has a thickness of ± 5% of half the thickness of the IC card.
An IC card, wherein the IC card is arranged within the range of. 5. The IC card according to claim 1, wherein a protective insulating film for ionic contaminants is formed on a back surface of said IC chip. 6. The IC card according to claim 1, wherein said IC chip is bonded to said flexible substrate via an adhesive. 7. The IC card according to claim 1, wherein the strength of the IC chip is increased by using a plastic or a metal material. 8. An IC chip having a thickness of 5 to 10 μm, wiring connected to the IC chip, and first and second flexible substrates disposed so as to sandwich the IC chip and the wiring. With an IC card
There are, said IC chip, said one surface when the IC card is bent under compressive stress, the other side is to receive a tensile stress
The IC card is disposed on a neutral surface of the IC card, and the IC card is curved and bent. 9. The IC card according to claim 8, wherein said IC chip is bonded to said first flexible substrate with a rubber-like adhesive. 10. The IC card according to claim 8, wherein said IC chip and said wiring are connected by a liquid conductive material. 11. A thickness of less 110 [mu] m IC chip, an IC card which have a first and second flexible substrate disposed so as to sandwich the IC chip, the IC chip, the first thinner than 1 and a second flexible substrate, the one surface when the IC card is bent under compressive stress, prior to the other surface is subjected to tensile stress
An IC placed on a neutral surface of the IC card, wherein the IC card is curved and bent.
card. 12. A first substrate having wiring formed thereon, an IC chip disposed on the first substrate and having a thickness of 110 μm or less, and a second substrate provided so as to cover the IC chip. an IC card for <br/> Yes bets, the IC chip is thinner than the first and second flexible substrate, the one surface when the IC card is bent under compressive stress, other surface Before undergoing tensile stress
An IC placed on a neutral surface of the IC card, wherein the IC card is curved and bent.
card. 13. A first substrate having wiring formed thereon, an IC chip disposed on the first substrate and connected to the wiring and having a thickness of 110 μm or less, and provided so as to cover the IC chip. a second substrate which is an IC card for <br/> Yes, the IC chip is smaller than the distance from the surface of the IC chip thickness to the IC card surface, the IC card is bent An IC card which is disposed on a neutral surface of the IC card so that one surface receives a compressive stress and the other surface receives a tensile stress when the IC card is bent, and the IC card is curved and bent. 14. A semiconductor device, comprising: a first substrate; a second substrate; a first substrate, a first substrate, and a second substrate. The first substrate is connected to a wiring disposed between the first substrate and the second substrate. IC
An IC card which have a chip, the IC chip is a thickness of 110μm or less, wherein the one surface when the IC card is bent under compressive stress, wherein such other surface is subjected to tensile stress IC Card neutral
An IC card arranged on a surface , wherein the IC card is curved and bent. 15. The IC card according to claim 14, wherein the strength of the IC chip is increased by using a plastic or a metal material. 16. A semiconductor device, comprising: a first substrate, a second substrate, and a wiring disposed between the first and second substrates and connected to a wiring disposed between the first and second substrates. IC
An IC card which have a chip, the IC chip is a thickness of 110μm or less, and the strength is enlarged by plastic or metallic material, the IC
The IC is characterized in that the IC card is arranged on a neutral surface of the IC card so that one surface receives a compressive stress and the other surface receives a tensile stress when the card is bent, and the IC card is curved and bent. card. 17. A flexible upper substrate, a flexible lower substrate on which wiring is formed, and an IC chip disposed between the upper substrate and the lower substrate, wherein the wiring is connected with a conductive adhesive. IC card to Yes
A chromatography-de, the IC chip is a thickness of 110μm or less, and the strength is enlarged by plastic or metallic material, the IC
The IC is characterized in that the IC card is arranged on a neutral surface of the IC card so that one surface receives a compressive stress and the other surface receives a tensile stress when the card is bent, and the IC card is curved and bent. card. 18. Whether the IC chip is flexible and the same material
In the IC card sandwiched between the substrates, the IC chip has a thickness of 110 μm or less, and is provided within a range of ± 5% of a half of the thickness of the IC card. An IC card characterized in that the IC card is curved and bent when pressed. 19. The IC card according to claim 18, wherein the strength of the IC chip is increased by using a plastic or a metal material. 20. An IC card having an IC chip sandwiched between flexible boards, wherein the IC chip has a thickness of 110 μm or less, is provided on a neutral surface of the IC card, and the IC card is bent. An IC card characterized in that the IC card is curved and bent when pressed. 21. The IC card according to claim 20, wherein the strength of the IC chip is increased by using a plastic or a metal material. 22. An IC card in which an IC chip is sandwiched between flexible substrates, wherein the IC chip has a thickness of 110 μm or less, is provided on a neutral surface of the IC card, and is more limited than the substrate. When the curvature is small and the IC card is bent,
An IC card, wherein the IC card is curved and bent. 23. The IC card according to claim 22, wherein the strength of the IC chip is increased by using a plastic or a metal material.