Semiconductor device having a flexible printed circuit Number:7,436,050 from the United States Patent and Trademark Office (PTO) owispatent To provide a thin film device which becomes possible to be formed in the portion which has been considered impossible to be provided with such device by the conventional technique, and to provide a semiconductor device which occupies small space and which has high shock resistance and flexibility, a device formation layer with a thickness of at most 50 .mu.m which was peeled from a substrate by a transfer technique is transferred to another substrate, hence, a thin film device can be formed over various substrates. For instance, a semiconductor device can be formed so as to occupy small space by pasting a thin film device which is transferred to a flexible substrate onto a rear surface of a substrate of a panel, by pasting directly a thin film device onto a rear surface of a substrate of a panel, or by transferring a thin film device to an FPC which is pasted onto a substrate of a panel.<H Semiconductor, flexible, Semiconductor, d, 7436050.html, Patent, pto, 7436050

Title: Semiconductor device having a flexible printed circuit

Abstract: To provide a thin film device which becomes possible to be formed in the portion which has been considered impossible to be provided with such device by the conventional technique, and to provide a semiconductor device which occupies small space and which has high shock resistance and flexibility, a device formation layer with a thickness of at most 50 .mu.m which was peeled from a substrate by a transfer technique is transferred to another substrate, hence, a thin film device can be formed over various substrates. For instance, a semiconductor device can be formed so as to occupy small space by pasting a thin film device which is transferred to a flexible substrate onto a rear surface of a substrate of a panel, by pasting directly a thin film device onto a rear surface of a substrate of a panel, or by transferring a thin film device to an FPC which is pasted onto a substrate of a panel.

Patent Number: 7,436,050 Issued on 10/14/2008 to Yamazaki, et al.

Inventors: Yamazaki; Shunpei (Tokyo, JP), Takayama; Toru (Kanagawa, JP), Maruyama; Junya (Kanagawa, JP), Goto; Yuugo (Kanagawa, JP), Ohno; Yumiko (Kanagawa, JP), Arai; Yasuyuki (Kanagawa, JP), Shibata; Noriko (Kanagawa, JP)
Assignee: Semiconductor Energy Laboratory Co., Ltd. (Kanagawa-ken, JP)

Appl. No.: 10/760,723

Filed: January 21, 2004

Foreign Application Priority Data


Jan 22, 2003 [JP]			2003-014034

Current U.S. Class: 257/678 ; 257/E23.175

Current International Class: G09G 3/36 (20060101)

Field of Search: 257/347,678,783,E23.175,E23.177

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Primary Examiner: Dickey; Thomas L
Attorney, Agent or Firm: Fish & Richardson P.C.

Claims

What is claimed is:

1. A semiconductor device comprising: a panel comprising: a substrate; a pixel portion formed over the substrate; and a driver circuit formed over the substrate, and a flexible printed circuit connected to the panel, wherein an integrated circuit is mounted on the flexible printed circuit, wherein the integrated circuit comprises a flexible substrate and a device formation layer attached to the flexible substrate through an adhesive layer, and wherein the device formation layer includes a plurality of thin film transistors.

2. A semiconductor device according to claim 1, the integrated circuit includes at least one selected from the group consisting of a controller, a CPU, and a memory.

3. The semiconductor device according to claim 1, wherein the adhesive layer comprises a curing adhesive selected from the group consisting of a photo-curing adhesive, a UV cure adhesive, and an anaerobic adhesive.

4. The semiconductor device according to claim 1, wherein each of the thin film transistors is covered with an organic insulating film.

5. The semiconductor device according to claim 1, wherein each of the thin film transistors in the plurality of thin film transistors is an amorphous silicon thin film transistor or a polysilicon thin film transistor.

6. The semiconductor device according to claim 1, wherein the integrated circuit has a thickness of at most 50 .mu.m.

7. The semiconductor device according to claim 1, further comprising: a wiring on the flexible printed circuit; and a bump on the wiring; wherein the bump is connected to the integrated circuit comprising the flexible substrate and the device formation layer attached to the flexible substrate through the adhesive layer.

8. A semiconductor device comprising: a panel comprising: a substrate; a pixel portion formed over the substrate; and a driver circuit formed over the substrate, and a flexible printed circuit connected to the panel, wherein an integrated circuit is mounted on the flexible printed circuit, wherein the integrated circuit comprises a flexible substrate, wherein the integrated circuit is formed by sticking a device formation layer including a plurality of thin film transistors to the flexible substrate.

9. A semiconductor device according to claim 8, the integrated circuit includes at least one selected from the group consisting of a controller, a CPU, and a memory.

10. The semiconductor device according to claim 8, wherein the device formation layer including a plurality of thin film transistors is stuck to the flexible substrate directly.

11. The semiconductor device according to claim 8, wherein each of the thin film transistors is covered with an organic insulating film.

12. The semiconductor device according to claim 8, each of the thin film transistors in the plurality of thin film transistors is an amorphous silicon thin film transistor or a polysilicon thin film transistor.

13. The semiconductor device according to claim 8, wherein the integrated circuit has a thickness of at most 50 .mu.m.

14. The semiconductor device according to claim 8, further comprising: a wiring on the flexible printed circuit; and a bump on the wiring; wherein the bump is connected to the integrated circuit comprising the flexible substrate and the device formation layer attached to the flexible substrate through the adhesive layer.

15. A personal computer comprising: a panel comprising: a substrate; pixel portion formed over the substrate; and a driver circuit formed over the substrate, and a flexible printed circuit connected to the panel, wherein an integrated circuit is mounted on the flexible printed circuit, wherein the integrated circuit comprises a flexible substrate and a device formation layer attached to the flexible substrate through an adhesive layer, wherein the device formation layer includes a plurality of thin film transistors.

16. The semiconductor device according to claim 15, wherein the adhesive layer comprises a curing adhesive selected from the group consisting of a photo-curing adhesive, a UV cure adhesive, and an anaerobic adhesive.

17. The semiconductor device according to claim 15, wherein each of the thin film transistors is covered with an organic insulating film.

18. The semiconductor device according to claim 15, wherein each of the thin film transistors in the plurality of thin film transistors is an amorphous silicon thin film transistor or a polysilicon thin film transistor.

19. The semiconductor device according to claim 15, wherein the integrated circuit has a thickness of at most 50 .mu.m.

20. The semiconductor device according to claim 15, further comprising: a wiring on the flexible printed circuit; and a bump on the wiring; wherein the bump is connected to the integrated circuit comprising the flexible substrate and the device formation layer attached to the flexible substrate through the adhesive layer.

21. A semiconductor device comprising: a panel having a display portion; a flexible printed circuit attached to said panel; and an integrated circuit mounted on the flexible printed circuit, wherein the integrated circuit comprises a flexible substrate and a device formation layer attached to the flexible substrate through an adhesive layer, the device formation layer comprising a thin film transistor.

22. The semiconductor device according to claim 21 wherein said integrated circuit includes a CPU.

23. The semiconductor device according to claim 21 further comprising a driver circuit over the panel.

24. The semiconductor device according to claim 21 wherein said integrated circuit includes a memory.

25. The semiconductor device according to claim 21 wherein said integrated circuit includes a controller.

26. The semiconductor device according to claim 21 wherein said panel is a passive matrix type display device.

27. The semiconductor device according to claim 21 wherein said panel is an active matrix type display device.

28. The semiconductor device according to claim 21, wherein the thin film transistor is covered with an organic insulating film.

29. The semiconductor device according to claim 21, wherein said thin film transistor is an amorphous silicon thin film transistor or a polysilicon thin film transistor.

30. The semiconductor device according to claim 21, wherein said integrated circuit has a thickness of at most 50 .mu.m.

31. The semiconductor device according to claim 21, further comprising: a wiring on the flexible printed circuit; and a bump on the wiring; wherein the bump is connected to the integrated circuit comprising the flexible substrate and the device formation layer attached to the flexible substrate through the adhesive layer.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a transfer technique of manufacturing a device formation layer including a semiconductor device composed of a plurality of thin film transistors (hereinafter, TFT).

2. Related Art

In recent years, a technique for forming a TFT using a semiconductor thin film (having a thickness of from approximately several to several hundreds nm) formed over a substrate having an insulating surface has been attracted attention. A TFT is utilized widely for an electronic device such as an IC, an electro-optical device, or the like.

As a substrate for forming these TFTs, a glass substrate or a quartz substrate is widely used now, however, these substrates have some drawbacks such as being fragile and heavy. Further, these substrates are unsuitable for mass-production since it is difficult to use a large-sized glass substrate or a large-sized quartz substrate. Therefore it has been attempted that a device composed of TFTs is formed over a substrate having flexibility as typified by a flexible plastic film.

However, the maximum temperature of the process should be lowered since the heat resistance of a plastic film is low, with the result that a TFT having better electric characteristics than those of a TFT formed over a glass substrate cannot be formed. Thus, a semiconductor device, a display device, or a light-emitting device including a TFT which is directly formed over a substrate has not been realized yet.

At the same time, a technique for forming a thin film device over a glass substrate or a quartz substrate, and peeling the thin film device (transferred body) from the substrate, then transferring to a subject such as a plastic substrate, etc. are disclosed. (For example, Unexamined Patent Publication No. 10-125929)

If a semiconductor device, a display device, or a light-emitting device can be manufactured over a substrate having flexibility such as a plastic film, these devices can be utilized for a display of being thin, lightweight, flexible, and curved, so that the range of application can be broaden out.

SUMMARY OF THE INVENTION

It is an object of the present invention is to form a thin film device over various substrates to make it possible for the thin film device to be formed in the portion which has been considered impossible to be provided with such a device by the conventional technique. A further object of the invention is to provide a semiconductor device which occupies small space and which has high shock resistance and flexibility.

According to the invention, a device formation layer with a thickness of at most 50 .mu.m which was peeled from a substrate by a transfer technique is transferred to another substrate, hence, a thin film device can be formed over various substrates. As a substrate which is transferred with a device formation layer, various materials can be selected depending on purposes. Especially, a flexible substrate is better, since a thin film device which has high shock resistance and flexibility can be formed. A TFT included in a device formation layer refers to an amorphous silicon TFT(a-Si TFT) formed by using an amorphous semiconductor layer as an active layer, a polysilicon TFT (p-Si TFT) formed by using a crystalline semiconductor layer as an active layer.

According to the invention, a device formation layer can be directly transferred to a substrate by a transfer technique, but a device formation layer can be once transferred to an auxiliary substrate by a transfer technique to complete a chip, and the chip can be pasted onto a desired portion over the substrate.

A flexible substrate such as a plastic substrate is preferably used for a substrate which is transferred with a thin film device since an advantage of a transfer technique can be taken, that is, a device can be formed over any substrate. In addition, the thin film device can be further integrated by transferring repeatedly a device formation layer with a thickness at most 50 .mu.m which was peeled from another substrate to another device formation layer which was formed in advance.

According to the invention, on the basis of a fact that a device formation layer has a thickness of at most 50 .mu.m and is susceptible to be deteriorated due to heat generated in the device formation layer itself, a thermal conductive material which can radiate heat effectively can be used for a substrate. In case that another device formation layer is transferred to a device formation layer which was transferred in advance, a thermal conductive thin film is preferably formed over the surface of the transferred device formation layer.

As one of constitutions of the invention, a semiconductor device comprises a panel including a pixel portion and a driver circuit, each of which is formed over a substrate; a flexible printed circuit connected to the panel; wherein the flexible printed circuit is provided with an integrated circuit and the integrated circuit is formed by sticking a device formation layer including a plurality of thin film transistors to a flexible substrate.

As one of constitutions of the invention, a semiconductor device comprises a panel including a pixel portion and a driver circuit, each of which is formed over a substrate; a flexible printed circuit connected to the panel; wherein the flexible printed circuit is provided with a integrated circuit and the integrated circuit is formed by sticking a device formation layer including a plurality of thin film transistors on the flexible printed circuit directly.

As one of constitutions of the invention, a semiconductor device comprises a a pixel portion and a driver circuit, each of which is formed over a substrate, wherein the driver circuit is formed by sticking a device formation layer including a plurality of thin film transistors to a flexible substrate.

As one of constitutions of the invention, a semiconductor device comprises a pixel portion and a driver circuit, each of which is formed over a substrate, wherein the driver circuit is formed by sticking a device formation layer including a plurality of thin film transistors to the substrate directly.

Therefore, in the above described constitution, the driver circuit is separately formed, and is transferred to a desired portion over a panel by a transfer technique, instead that the driver circuit is formed over a substrate as in the same way that the pixel portion is formed. Here, the driver circuit can be directly transferred to a substrate of a panel, but the driver circuit can also be pasted over a desired position over a substrate of a panel via solder balls after transferring to an auxiliary substrate which was provided with wrings in advance.

As one of constitutions of the invention, a semiconductor device comprises a panel including a substrate having a front surface and a rear surface, a pixel portion and a driver circuit, each of which is formed over the front surface of the substrate, wherein an integrated circuit is formed by sticking a device formation layer including a plurality of thin film transistors on the rear surface of the substrate.

As one of constitutions of the invention, a semiconductor device comprises a panel including a substrate having a front surface and a rear surface, a pixel portion and a driver circuit, each of which is formed over the front surface of the substrate, wherein an integrated circuit is formed by sticking a device formation layer including a plurality of thin film transistors to the rear surface of the substrate directly.

In the above described constitution, the integrated circuit is directly transferred (stuck) to a rear surface of a panel instead of forming over a flexible substrate by a transfer technique.

The integrated circuit includes at least one selected from the group consisting of a controller, a CPU, or a memory.

In each above described constitution, a semiconductor device according to the present invention includes a CPU (Central Processing Unit), an MPU (Micro Processor Unit), a memory, a microcomputer, an image processor, a display device, and further, a module which is installed with these devices. The display device according to the present invention refers to a liquid crystal display device, a PDP (Plasma Display Panel), an FED (Field Emission Display), an electronic paper, a light-emitting device, or the like. The light-emitting device includes an electroluminescent device, or the like. In addition, the panel may be either an active matrix panel or a passive matrix panel.

According to the invention, a thin film device becomes possible to be formed in the portion which was impossible to be provided with such device by the conventional technique. Therefore a semiconductor device which occupies small space and which has high shock resistance and flexibility can be provided.

BRIEF DESCRIPTION OF THE INVENTION

FIGS. 1A to 1C are explanatory views of a constitution according to the present invention explained in embodiment 1;

FIGS. 2A to 2C are explanatory views of a constitution according to the present invention explained in embodiment 1;

FIGS. 3A to 3C are explanatory views of a constitution according to the present invention explained in embodiment 2;

FIGS. 4A to 4C are explanatory views of a constitution according to the present invention explained in embodiment 3;

FIGS. 5A to 5C are explanatory views of a constitution according to the present invention explained in embodiment 4;

FIGS. 6A to 6C are explanatory views of a transfer technique;

FIGS. 7A to 7C are explanatory views of a transfer technique;

FIGS. 8A to 8D are explanatory views of a process for manufacturing a TFT;

FIGS. 9A to 9D are explanatory views of a process for manufacturing a TFT;

FIGS. 10A and 10B are explanatory views of a process for mass-production by using a transfer technique;

FIG. 11 is an explanatory view of a configuration of a CPU;

FIG. 12 is a timing chart of an operation of a CPU having the configuration described with reference to FIG. 11;

FIGS. 13A and 13B are photograph of a CPU according to the invention;

FIGS. 14A and 14B are photograph of a CPU according to the invention; and

FIGS. 15A to 15G are explanatory views of electronic equipments.

These and other objects, features and advantages of the present invention will become more apparent upon reading of the following detailed description along with the accompanied drawings.

DETALED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the present invention will be explained in detail.

Embodiment 1

A module (semiconductor module), which is provided with an integrated circuit formed by a transfer technique over an FPC (Flexible Printed Circuit) for connecting electrically a panel 100 to outside will be explained in this embodiment with reference to FIGS. 1A to 1C.

FIG. 1A is a top view of a semiconductor module. FIG. 1B is a cross-sectional view of the semiconductor module. The panel 100 is provided with a pixel portion 105 and a driver circuit (a signal line driver circuit 107, a scanning line driver circuit 106). An FPC (Flexible Printed Circuit) 108 for connecting electrically the driver circuit to an external power source or the like provided at outside (not shown) is pasted over the panel 100 with an adhesive 109.

Further, an integrated circuit (a controller 101, CPU (Central Processing Unit) 102, a memory 103) is formed over the FPC 108 by the transfer technique.

In addition, the integrated circuit (a controller 101, CPU (Central Processing Unit) 102, a memory 103) can be formed to have a thickness of at most 50 .mu.m by the transfer technique. Therefore, the integrated circuit becomes possible to be formed over a flexible film such as the FPC 108. Even if a physical force is applied to the FPC 108 and the FPC 108 bends due to the force as shown in FIG. 1B, the integrated circuit formed by the transfer technique can be used for the FPC without undermining its function since the integrated circuit can meet such deformation.

FIG. 1C is an enlarged view of the CPU 102 which is a part of the integrated circuit formed over the FPC 108 shown in FIG. 1B.

A device formation layer 112 composed of a plurality of TFTs 111 is transferred to a flexible auxiliary substrate 113 by a transfer technique (double transfer, in this instance), and is electrically connected to a wiring 115 which is formed over the FPC 108 via bumps 114. Here, the case that the device formation layer 112 is electrically connected to the wiring 115 which is formed over the FPC 108 by the bumps 114 after the device formation layer 112 is transferred to the auxiliary substrate 113 is exemplified. However, the invention is not limited to the case, that is, the device formation layer 112 can be electrically and directly connected to the wiring 115 without using the auxiliary substrate 113 and the bumps 114. In addition, a way of the double transfer will be explained in detail in embodiment 5.

As another way of forming an integrated circuit over an FPC, an integrated circuit which is transferred to an FPC 208 can be grown in size as shown in FIGS. 2A and 2B.

The integrated circuit in this case may be formed in such a way that an integrated circuit 210 formed by transferring respectively a controller, a CPU, a memory, and the like, is formed over a large flexible auxiliary substrate, and the substrate with the integrated circuit 210 is pasted onto the FPC 208 as shown in FIG. 2A. Besides, an integrated circuit 205 composed of a controller 211, a CPU 212, a memory 213, and the like is transferred to an auxiliary substrate 214, and the substrate 214 transferred with the integrated circuit 205 may be pasted onto an FPC 216.

A large integrated circuit which is transferred to an FPC as described above makes it possible that a margin for transferring can be set wide so that alignment in transferring (pasting) can be carried out easily.

As a transfer technique according to the present invention, single transfer, that is, a device formation layer 222 formed over a substrate is transferred to the region where the device formation layer 222 can electrically connected to a wiring 225, which is formed over a substrate (here, an FPC 228), via bumps 224, and the substrate is separated, can be carried out. In this case, the form shown in FIG. 2C is obtained.

Embodiment 2

A module (semiconductor module) in which a driver circuit over a panel is formed by a transfer technique is explained in this embodiment with reference to FIGS. 3A to 3C.

FIG. 3A is a top view of a semiconductor module. A panel 300 is provided with a pixel portion 305 and a driver circuit (a signal line driver circuit 307, a scanning line driver circuit 306). An FPC (Flexible Printed Circuit) 308 for connecting electrically the driver circuit to an external power source or the like provide at outside (not shown) is pasted onto the panel 300 with an adhesive 309.

In this embodiment, the driver circuit (the signal line driver circuit 307, the scanning line driver circuit 306) is formed by a transfer technique. Consequently, in case of using a flexible substrate to manufacture a panel, the driver circuit can be formed easily over the flexible substrate.

FIG. 3B is an enlarged view of the driver circuit (the signal line driver circuit 307, the scanning line driver circuit 306) formed over the panel. Hereinafter, a structure of a chip in which a device formation layer 312 is transferred to an auxiliary substrate 314 will be explained in detail.

As shown in FIG. 3B, the device formation layer 312 composed of a plurality of TFTs 311 is formed by a transfer technique over the auxiliary substrate 314 which is flexible. In addition, the auxiliary substrate 314 is provided with a wiring 315 in advance. The device formation layer 312 which is transferred is electrically connected to the wiring 315 via bumps 313. Further, the device substrate 312 is pasted onto a panel 300 via solder balls 316 connected electrically to the wiring 315, consequently, wirings (not shown) over the panel 300 can be electrically connected to the driver circuit.

FIG. 3C is an enlarged view of reference numeral 323 in FIG. 3B. A plurality of wirings included in the device formation layer 312 are leaded out by a leading out wiring 321 as shown in FIG. 3C. Bumps 313 formed in contact with the leading out wiring 321 are electrically connected to the wiring 315 over the auxiliary wiring 314 via an anisotropic conductive adhesive layer 317.

As a material for the anisotropic conductive adhesive layer 317, anisotropic conductive particles 325 formed by covering metal particles such as Ag, Au, Al, or the like with insulating films, and an adhesive 324 selected from various curing adhesives, for example, a photo-curing adhesive such as a reaction-curing adhesive, a thermosetting adhesive, or a UV cure adhesive, or an anaerobic adhesive can be used. In the anisotropic conductive adhesive layer 317, the bumps 313 and the wiring 315 over the auxiliary substrate 314 are electrically connected each other via the anisotropic conductive particles 325.

Therefore a driver circuit formed by pasting a chip, which is formed by transferring a driver circuit to the auxiliary substrate 314 which is flexible, onto the panel 300 via the solder balls 316 can be used without undermining its function even if a shape of the substrate bends due to a physical force since the driver circuit has flexibility to meet such deformation.

Further, even if deterioration is discovered in one chip, yields can be improved by exchanging the deteriorated chip for a normal chip.

In this embodiment, the case that each the signal line driver circuit 307 and the scanning line driver circuit 306 is formed by pasting a plurality of semiconductor chips onto a panel is explained, but not exclusively, the signal line driver circuit 307 and the scanning line driver circuit 306 can be formed by pasting one chip onto a panel respectively.

Embodiment 3

In this embodiment, the case that an integrated circuits (a controller 401, a CPU 402, a memory 403) formed over a flexible substrate by a transfer technique is wholly pasted onto a rear surface of a panel will be explained with reference to FIG. 4.

FIG. 4A is a top view of a semiconductor module. FIG. 4B is a cross-sectional view of the semiconductor module. A panel 400 is provided with a pixel portion 405 and a driver circuit (a signal line driver circuit 407, a scanning line driver circuit 406). An FPC (Flexible Printed Circuit) 408 for connecting electrically the driver circuit to an external power source or the like provided at outside (not shown) is pasted onto the panel 400 with an adhesive 409.

A rear surface of the panel 400 is pasted with a flexible substrate 412 provided with an integrated circuit (a controller 401, a CPU 402, a memory 403) with an adhesive 413 by the transfer technique (double transfer) as shown in FIG. 4B.

The integrated circuit (a controller 401, a CPU 402, a memory 403) is formed over a flexible substrate 412 by the transfer technique. The integrated circuit can be easily pasted by its flexibility over a substrate 411 for forming a panel.

FIG. 4C is an enlarged view of a pixel portion 405 and a CPU 402 shown in FIG. 4B.

Therefore the panel 400 is transferred with TFT and a device formation substrate 425 which composed pixels and includes devices, and is provided with the pixel portion 405. The same surface as the panel 400 is transferred with a device formation layer which composes a driver circuit, and is provided with a driver circuit (a signal line driver circuit 407, a scanning line driver circuit 406) (not shown).

Further, the pixel portion 405 is provided with a liquid crystal device. Hence, a substrate 414 which included a counter electrode 417 is provided via liquid crystal 416 over the device formation layer 425 for forming a pixel portion 405.

A rear surface, which is not provided with the pixel portion 405, of the panel 400 is provided with the integrated circuit 415 such as the CPU 402 which is formed over the flexible substrate 412 by a transfer technique (double transfer). A surface of the integrated circuit 415 where wirings are exposed is pasted onto the panel 400 with the adhesive 413. As a material for the adhesive 413, various curing adhesives, for example, a photo-curing adhesive such as a reaction-curing adhesive, a thermal-curing adhesive, or a UV cure adhesive, or an anaerobic adhesive can be used.

In this embodiment, a wiring of the integrated circuit 415 is electrically connected to the FPC 408 at a region denoted by reference numeral 420 shown in FIG. 4B.

According to this embodiment, a semiconductor device can be downsized to occupy as small space as possible since an integrated circuit can be formed over a rear surface of a panel and is unnecessary to be provided at outside.

Embodiment 4

In this embodiment, a module (semiconductor module) will be explained with reference to FIGS. 5A to 5C, in which an integrated circuit is formed over a rear surface of a substrate, which will be provided with a pixel portion and a driver circuit, by way of the following manner, that is, a chip, which is formed by transferring an integrated circuit to an auxiliary substrate, is pasted onto a rear surface of a substrate transferred with a device formation layer which composes pixels. The module is different from that explained in embodiment 3.

FIG. 5A is a top view of a semiconductor module. FIG. 5B is a top view of a rear surface of the semiconductor module. FIG. 5C is a cross-sectional view of the semiconductor module. In this embodiment, a panel is preferably formed by using a flexible substrate that can be transformed into another shape since an advantage of transfer that enable a device formation layer to be easily formed over also a flexible substrate can be taken.

A panel 500 is provided with a pixel portion 505 and a driver circuit (a signal line driver circuit 507, a scanning line driver circuit 506). An FPC (Flexible Printed Circuit) 508 for connecting electrically the driver circuit to an external power source or the like provided at outside (not shown) is pasted onto the panel 500 with an adhesive 509.

A rear surface of the panel 500 is pasted with a chip provided with an integrated circuit 512 (a controller 501, a CPU 502, a memory 503) with an adhesive by a transfer technique (double transfer) as shown in FIG. 5B.

The integrated circuit (a controller 501, a CPU 502, a memory 503) is transferred to a flexible auxiliary substrate, and pasted onto the panel 500. Even if a physical force is applied to the panel 500 and the panel 500 bends due to the force as shown in FIG. 5B, the integrated circuit formed by a transfer technique can be used for the panel without undermining its function since the integrated circuit has flexibility to meet such deformation.

As shown in FIG. 5C, a pixel portion and a driver circuit formed over a surface of a panel are electrically connected to the integrated circuit (a controller 501, a CPU 502, a memory 503) by an auxiliary wiring 513. As a material for forming the auxiliary wiring 512, Au, Cu, Al, Al--Si, Au alloys, or the like can be used.

In this embodiment, the FPC 508 is pasted onto a rear surface of the panel with the adhesive 509. The FPC 508 is electrically connected to the integrated circuit 512 (a controller 501, a CPU 502, a memory 503) which is pasted onto a panel, and to a pixel portion 505 and the driver circuit (a signal line driver circuit 507, a scanning line driver circuit 506) via a wiring (not shown) formed over the rear surface of the panel and via the auxiliary wiring 513.

According to this embodiment, a semiconductor device can be downsized to occupy as small space as possible since an integrated circuit can be formed over a rear surface of a panel and is unnecessary to be provided at outside.

Embodiment 5

In this embodiment, a transfer technique (double transfer) will be explained in detail with reference to FIGS. 6A to 6C and 7A to 7C.

FIG. 6A is a view of showing a state that a metal layer 601, a metal oxide layer 602, and an oxide layer 603 are sequentially stacked over a first substrate 601, and a device formation layer 604, which includes a plurality of TFTs and wirings, is formed thereon.

As the first substrate 600, a glass substrate, a quartz substrate, a plastic substrate, a ceramic substrate, a silicon substrate, a metal substrate, or a stainless substrate, or the like, can be used. AN 100, which is a glass substrate, is used in this embodiment.

As materials for the metal layer 601 formed over the first substrate 600, an element selected from the group consisting of W, Ti, Ta, Mo, Nd, Ni, Co, Zr, Zn, Ru, Rh, Pd, Os, Ir, and Pt; a single layer formed of an alloy material or a compound material, each of which contains these elements as their main com