JP2002229061A - Thin-film semiconductor device and reflection-type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower resistance of wiring, without increasing the number of process steps by using metallic materials constituting a reflection film for additional wiring, in addition to the original wiring of driving circuits. SOLUTION: The thin-film semiconductor device consists of a pixel array section, which is composed of pixels PLXs arranged in a matrix form and reflects incident light from outside by each of the respective pixels PLXs,; a drive circuit section which is composed of plural thin-film transistors TFTs and the first wiring 7 for connecting the same and drives the pixel array section and an insulating substrate 1, which is formed integrally with the pixel array section and the drive circuit section. The pixel array section has the reflection film 9, consisting of a metallic material in order to reflect the incident light from outside and the drive circuit section includes the second wiring 10 formed of the same material as the metallic material of the reflection film 9. The second wiring 10 is laminated on the first wiring 7 across a planarizing film 8 and is electrically connected to the first wiring 7 across contact holes opened in the planarizing film 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a thin film semiconductor device and a reflection type display device using the same as a driving substrate. More specifically, the present invention relates to a wiring structure of a thin film semiconductor device using a reflection film.

[0002]

2. Description of the Related Art A conventional reflective display device is known which comprises a pixel array section and a drive circuit section.
The pixel array unit includes pixels arranged in a matrix, and reflects light incident from outside on each pixel to display an image. The drive circuit unit includes a plurality of thin film transistors and a first wiring connecting the thin film transistors, and drives the pixel array unit. The pixel array section and the drive circuit section are integrally formed on an insulating substrate. The pixel array section is
A reflection film made of a metal material is provided to reflect light incident from the outside. As described above, in the reflective display device integrated with the peripheral driving circuit unit, the peripheral driving circuit unit is, for example, a CM.
It is integrated and formed by thin film transistors centering on the OS, and a normal thin film transistor process is used. On the other hand, in the pixel array part, to form a reflective film,
A specific metal material was used.

[0003]

In recent years, demands for reducing the area of the drive circuit portion occupied on the chips constituting the display panel and increasing the number of chips to be cut out from the wafer have increased in terms of cost. In addition, there has been a strong demand to increase the ratio of the size of the pixel array section to the chip size (because the pixel array section forms a screen, the above ratio is hereinafter referred to as the screen rate).
For this purpose, it is necessary to reduce the wiring width of the thin film transistor group forming the drive circuit section, and to further miniaturize the drive circuit section. However, in a large display panel having a large screen size, a distance between a terminal for external connection and a drive circuit unit becomes long, and the wiring resistance must be reduced. Therefore, if the wiring width is made extremely narrow in order to reduce the size of the drive circuit section, the wiring resistance will increase, which is a problem. Therefore, in order to reduce the wiring width without reducing the wiring resistance as much as possible, attempts have been made to lower the wiring material and increase the thickness of the wiring material. Incidentally, the volume resistance of aluminum, which is conventionally widely used, is 2.7 μΩ · cm, whereas the volume resistance of copper is 1.7 μΩ · cm, and the volume resistance of silver is 1.6 μΩ.
・ Cm. However, aluminum is very stable and easy to use, so it is difficult to easily replace it with copper or silver. On the other hand, if the thickness of the aluminum wiring is increased to reduce the resistance, etching for patterning takes time, which is not suitable for mass production.

On the other hand, Japanese Patent Application Laid-Open No. 10-288797 proposes a device in which a metal material used for a reflection film of a pixel array portion is used for wiring of a peripheral driving circuit. However, simply forming the wiring from a metal material does not contribute to reducing the resistance of the wiring. Accordingly, an object of the present invention is to reduce the resistance of a wiring without increasing the number of steps by using a metal material forming a reflective film for an additional wiring in addition to the original wiring of the drive circuit unit. .

[0005]

Means for Solving the Problems In order to solve the above-mentioned problems of the prior art and to achieve the object of the present invention, the following measures have been taken. That is, the present invention is configured by a pixel array unit configured by pixels arranged in a matrix and reflecting light incident from the outside for each pixel, a plurality of thin film transistors, and a first wiring connecting these. A thin-film semiconductor device comprising a driving circuit portion for driving a pixel array portion, and an insulating substrate formed integrally with the pixel array portion and the driving circuit portion, wherein the pixel array portion receives light from outside. A reflection film made of a metal material for reflecting the light, and the drive circuit section includes a second wiring formed of the same metal material as the reflection film. Preferably, the second wiring is stacked on the first wiring. Specifically, the second wiring is stacked on the first wiring via an insulating film, and is electrically connected to the first wiring via a contact hole opened in the insulating film. I have.
The first wiring is made of a laminated material or an alloy material mainly composed of aluminum or copper, and the second wiring is made of a laminated material or an alloy material mainly composed of aluminum or silver. Further, the second wiring is wider than the first wiring. Further, the second wiring is covered with a protective film.

According to the present invention, in a reflective display device in which a drive circuit section and a pixel array section are integrated, a peripheral drive circuit section includes a plurality of thin film transistors and a first wiring connecting these thin film transistors. Have been. Further, the driving circuit section includes a second wiring formed of the same metal material as the reflection film formed on the pixel array section. As described above, by combining the first wiring and the second wiring and using both in a complementary manner, the wiring resistance can be suppressed low. Specifically, by overlapping the second wiring on the first wiring, the resistance can be reduced.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic partial cross-sectional view showing an example of an embodiment of a thin film semiconductor device according to the present invention. As shown in the figure, in the present thin film semiconductor device, a pixel array section and a drive circuit section are integrally formed on an insulating substrate 1. The pixel array section includes pixels PXL arranged in a matrix, and reflects light incident from the outside for each pixel. In the figure, for simplicity, only one PXL is shown, and the drive circuit unit is composed of a plurality of thin film transistors (TFTs) and a first wiring 7 connecting them, and drives the pixel array unit. In the figure, only one TFT included in the drive circuit is shown for easy understanding. As described above, the pixel array unit and the drive circuit unit are connected to the insulating substrate 1.
Are integrally formed. The insulating substrate 1 is made of, for example, plastic or glass. Here, the pixel array section includes a reflective film 9 made of a metal material for reflecting light incident from the outside. On the other hand, the peripheral drive circuit section includes a second wiring 10 formed of the same metal material as the reflection film 9. As shown in the drawing, the second wiring 10 is stacked on the first wiring 7, and the two are in a complementary relationship. That is, by laminating the first wiring 7 and the second wiring 10, the wiring resistance can be reduced, and the wiring width can be reduced correspondingly, which can contribute to the reduction of the area of the drive circuit portion. As a specific structure, the second wiring 10 is stacked on the first wiring 7 via a flattening film 8 which is a kind of insulating film, and is formed via a contact hole opened in the flattening film 8. It is electrically connected to one wiring 7. Preferably, the second wiring 10
Is made of a laminated material or alloy material mainly composed of aluminum or silver. On the other hand, the first wiring 7 is made of a laminated material or an alloy material mainly composed of aluminum or copper. For example, the second wiring 10 is made of an alloy obtained by adding gold or copper for preventing migration to silver. The first wiring 7 is a laminate in which an upper aluminum layer and a lower titanium layer are stacked. Generally, the second wiring 10 is formed wider than the first wiring 7. In some cases, conversely, the width of the second wiring 10 may be narrower than the width of the first wiring 7. In some cases, the second wiring 10 may be covered with a protective film to prevent corrosion and the like.

In general, as the wiring material, in the case of the first wiring 7, Ti / Al, Ti / Al / Mo, Ti / Al / T
i and Al are mainly used. In the future, low-resistance Cu wiring will be used instead of Al wiring. In a typical example, a laminated material in which a lower AL and an upper Ti are stacked is used. For the lower layer, AL is used because contact with a semiconductor thin film such as polysilicon is important. The upper layer is made of A using Ti
The contact resistance between L and the second wiring 10 is reduced. Since the second wiring 10 is also used as the reflection film 9, Ag is generally preferable. However, when a large amount of current flows through Ag, a migration phenomenon occurs and the wiring may be cut. So Ag
Ag / Pd / Cu, Ag / Pd / Al, etc., which are alloys of the above, are used. Depending on the application, an Al film may be used.

Referring to FIG. 1, the structure of the thin film semiconductor device will be described in detail. The pixel PXL includes a thin film transistor TFT of a double gate type and a bottom structure, and an auxiliary capacitance Cs. The thin film transistor TFT includes a pair of gate electrodes 2 connected to each other at the same potential, a two-layer gate insulating film 3 formed thereon, and a semiconductor thin film 4 formed thereon. Gate insulating film 3
Has a laminated structure in which, for example, a silicon nitride film and a silicon oxide film are stacked. The semiconductor thin film 4 is made of, for example, polysilicon. A stopper film 5 is formed on the semiconductor thin film 4 immediately above the gate electrode 2 to protect a channel region of the TFT. The auxiliary capacitance Cs also has basically the same laminated structure as the TFT, and the gate insulating film 3 sandwiched between the lower electrode 2c and the semiconductor thin film 4 constituting the upper electrode functions as a dielectric film. . It should be noted that the thin film transistor TFT integrated in the drive circuit section is also the same as the TFT formed in the pixel PXL.
It has a layer structure basically similar to FT, and is a bottom gate type. TFT and Cs having such a configuration are:
It is covered with an interlayer insulating film 6. The first wiring 7 is formed on the interlayer insulating film 6 by patterning. The first wiring 7 is electrically connected to the TFT via a contact hole opened in the interlayer insulating film 6. The first wiring 7 is covered with a flattening film 8. The surface of the planarizing film 8 has irregularities in the pixel region. A reflective film 9 is formed thereon by patterning. At this time, the second wiring 10 is also patterned at the same time. The reflection film 9 is electrically connected to the drain of the TFT via a contact hole opened in the flattening film 8 and functions as a pixel electrode. As described above, the second wiring 10 is electrically connected to the first wiring 7 via the contact hole opened in the flattening film 8 to obtain a redundant wiring structure.

FIG. 2 is a schematic plan view showing an example of a wiring pattern. In the example shown in (A), the first wiring 7 and the second wiring 10 are patterned in substantially the same shape. The first wiring 7 and the second wiring 10 are overlapped via an insulating film, and both are electrically connected to each other via a contact hole CON opened in the insulating film. As is clear from the figure, the second wiring 10 is used as an auxiliary to the first wiring 7 and greatly contributes to the reduction of the electric resistance of the first wiring 7. (B)
Is formed in a state where the second wiring 10 is discontinuously cut along the first wiring 7. Second wiring 1
0 are connected to the first wiring 7 via the contact holes CON. With such a configuration, the resistance of the first wiring 7 can be reduced. In the example shown in (C), the first wiring 7 and the second wiring 10 are formed with patterns shifted from each other. However, since the second wiring 10 and the first wiring 7 are electrically connected to each other by the contact holes CON at both ends, the wiring resistance is reduced as a whole. Thus, each wiring can be designed according to the degree of freedom of the layout. In addition, it is preferable that the second wiring 10 used as an auxiliary is provided only in a necessary portion to form the first wiring 7 into two layers. By doing so, the number of the second wirings 10 is reduced, and the degree of freedom of the area layout is increased.

Next, a method for manufacturing a thin film semiconductor device according to the present invention will be described in detail with reference to FIGS. In this embodiment, a thin film transistor having a bottom gate structure is integrated, but a thin film transistor having a top gate structure may be used. First, after a Mo film is formed on a substrate 1 made of glass or the like by sputtering or the like, patterning is performed according to a predetermined shape to form a gate electrode 2 for TFT and a lower electrode 2c for Cs. In the figure, a thin film transistor having a double gate structure for driving a pixel and an auxiliary capacitor are formed on the left side of the substrate 1, and a thin film transistor for a peripheral driving circuit is formed on the right side. Subsequently, a gate insulating film 3 and a semiconductor thin film 4 are formed on the substrate 1 as shown in (2). For example, CV
By using D, the gate insulating film 3 and the semiconductor thin film 4 can be continuously formed. As the gate insulating film 3, a silicon nitride film and a silicon oxide film are formed, and as the semiconductor thin film 4, for example, amorphous silicon is formed. Subsequently, as shown in (3), the substrate 1 is irradiated with a laser beam LB while scanning, thereby converting the semiconductor thin film 4 from amorphous silicon to polycrystalline silicon.

Subsequently, as shown in FIG. 4 (4), a silicon oxide film is formed on the crystallized semiconductor thin film 4, and is patterned into a predetermined shape by employing a backside exposure technique or the like, and a stopper is formed. Process into a film 5. Using the stopper film 5 as a mask, an impurity (for example, phosphorus) is ion-doped at a low concentration to form a so-called LDD region. Subsequently, as shown in (5), while the stopper film 5 is left on each gate electrode 2, the stopper film is removed from above the storage capacitor lower electrode 2c. Further, a mask M is formed with a photoresist so as to cover the stopper film 5 and its periphery. For example, impurity phosphorus (P) is implanted at a high concentration through the mask M to form a drain region and a source region of each thin film transistor and an upper electrode for an auxiliary capacitor. As described above, an N-type TFT having an LDD structure is obtained. Thereafter, when a P-type thin film transistor is formed in a peripheral driver circuit portion, for example, boron is ion-implanted as an impurity. Thereafter, as shown in (6), the semiconductor thin film 4 is etched in an island shape to separate each TFT and Cs from each other. As described above, the TFT and Cs are formed in the pixel array portion, and the TFT is also integratedly formed in the peripheral drive circuit portion.

Subsequently, as shown in FIG. 5 (7), the TFT and Cs are covered with an interlayer insulating film 6. Specifically, silicon oxide or the like is deposited by CVD to form the interlayer insulating film 6. Thereafter, as shown in (8), a contact hole is opened in the interlayer insulating film 6. Subsequently, AL and Ti are continuously formed on the interlayer insulating film 6 by a sputtering method, and are patterned into a predetermined shape to form a first wiring 7. In this example, first, for example, 50
Is deposited to a thickness of 0 nm, and Ti is deposited on the
m. Conversely, in some cases, Ti is sputtered first and then Al is sputtered. Finally (9)
The first wiring 7 is covered with a flattening film 8 as shown in FIG. For example, baking is performed after applying an acrylic resin by a spin coating method or the like. In the pixel array section, irregularities are formed on the surface of the flattening film 8 by etching. At the same time, necessary contact holes are also opened. After such processing, silver is formed on the flattening film 8 by a sputtering method, and the reflective film 9 is formed by patterning in a predetermined shape. The reflection film 9 functions as a pixel electrode, and is electrically connected to the drain of the TFT via the wiring 7. At this time, silver of the same material as that of the reflection film 9 is patterned to form the second wiring 10. As shown, the second wiring 10 is electrically connected to the lower first wiring 7 via a contact hole opened in the flattening film 8.

FIG. 6 is a schematic partial sectional view showing an example of a reflection type liquid crystal display device assembled using the thin film semiconductor device manufactured by the method shown in FIGS. To facilitate understanding, only a portion corresponding to one pixel is shown. On one substrate 1, a reflective film 9 functioning as a pixel electrode and a TFT for driving the pixel electrode are integrally formed. The TFT is a bottom gate type having a double gate structure. The portion of the semiconductor thin film 4 located immediately above each gate electrode 2 is covered with a stopper film 5 to form a channel region. LDD regions into which impurities are implanted at a low concentration are provided on both sides of the channel region. On the left side of the gate electrode 2 on the left side of the TFT having the double gate structure, a source region S into which impurities are implanted at a high concentration is formed, and on the right side of the gate electrode 2 on the right side, impurities are also implanted at a high concentration. Drain region D is formed. The reflection film 9 is electrically connected to the drain region D via the first wiring 7. On the other hand, on the inner surface of the upper substrate 20, a color filter 21 that is color-coded red, green, and blue for each pixel.
Alternatively, a counter electrode 22 made of a transparent conductive film is formed. Lower substrate 1 on which TFTs are integrated and counter electrode 2
2 and the upper substrate 20 on which the color filters 21 are formed, are joined to each other via a predetermined gap. Both substrates 1, 2
Between 0, the liquid crystal 23 is held as an electro-optical material to constitute a reflective display device.

FIG. 7 is a schematic diagram showing the entire configuration of the liquid crystal display (LCD) shown in FIG. 6 and a schematic diagram showing details of the pixel PXL. The LCD is a panel to which the latest technology is applied, and includes a central pixel array section and a peripheral driving circuit section. Pixel array part is 176 × 220 × R
It includes GB pixels. The peripheral drive circuit section includes an address driver, a DAC circuit, a DD converter, and the like. A terminal for external connection is provided at the left end of the panel having such a configuration. Since the distance from this terminal to the region where various circuits are arranged becomes longer, it is important to reduce the wiring resistance according to the present invention. Each pixel PXL integrated and formed in the pixel array section is divided into regions and is composed of a set of pixel electrodes subdivided into 4 bits. In addition, a memory (SRAM) is integrally formed in each pixel PXL in addition to a switching TFT.

FIG. 8 is a schematic perspective view showing a portable information terminal device according to the present invention. Personal digital assistant (PD
A) 300 has a compact structure in which an operation unit 311 for inputting an instruction, a processing unit 310 for processing information in accordance with the instruction, and a display unit 320 for displaying the processed information are integrated. . The processing unit 310 has basic functions as a PDA (a communication unit, a voice processing unit, a control unit, a storage unit, and the like). By controlling these functions by a control unit including a CPU, a telephone function, a mail function, a personal computer function, a personal computer communication function, a personal information management function, and the like can be realized. Further, an operation unit 311 is provided, and various functions can be selected by operating the operation unit 311. The processing unit 310 generates image information according to the content of processing to be performed. The display unit 320 displays the image information generated by the information processing unit 310. Here, the display unit 320
A reflective display device manufactured according to the present invention is used.

FIG. 9 is a schematic plan view showing an example of the portable telephone terminal device according to the present invention. As shown in the figure, the mobile phone terminal device 400 includes an operation unit for performing operations relating to outgoing and incoming calls, a communication unit for enabling a telephone call in accordance with the operations, and a display unit for displaying at least information relating to the operations. It has a compact structure that incorporates Specifically, the mobile phone terminal device 400 includes an antenna 431 for wireless transmission and reception, a receiver (speaker) 432, and a transmitter (microphone) 433, and also includes operation keys 434 such as dial keys and a display unit 435. ing. The display unit 435 is a reflective display device made according to the present invention. Mobile phone terminal device 400
Displays telephone directory information such as personal names and telephone numbers on the display unit 435.
Can be displayed. In some cases, the received e-mail can be displayed on the display unit 435.

[0018]

As described above, according to the present invention, in a reflection type display device integrated with a driving circuit, in order to reduce the wiring resistance of peripheral driving circuits, the reflection formed in the pixel array portion is reduced. The metal material constituting the film is used as a part of the wiring. Thereby, the wiring resistance can be reduced. Therefore, the area of the peripheral drive circuit section can be reduced, and the area of the pixel array section can be increased accordingly, so that the overall screen ratio can be increased. Further, since the size of the peripheral drive circuit section surrounding the central pixel array section like a frame can be reduced, the chip size (panel size) is reduced accordingly, and the yield per unit wafer is increased. In addition, since the additional wiring can be formed simultaneously with the patterning of the reflection film, the number of steps does not increase.

[Brief description of the drawings]

FIG. 1 is a schematic partial sectional view showing an embodiment of a thin film semiconductor device according to the present invention.

FIG. 2 is a schematic plan view showing an example of a pattern of a first wiring and a second wiring.

FIG. 3 is a process chart showing a method for manufacturing a thin film semiconductor device according to the present invention.

FIG. 4 is a process chart showing a method for manufacturing a thin film semiconductor device according to the present invention.

FIG. 5 is a process chart showing a method for manufacturing a thin-film semiconductor device according to the present invention.

FIG. 6 is a schematic partial cross-sectional view showing one example of a reflection type display device according to the present invention.

FIG. 7 is a schematic diagram illustrating an example of a reflective display device according to the present invention.

FIG. 8 is a perspective view showing an example of a portable information terminal device according to the present invention.

FIG. 9 is a schematic plan view showing an example of a mobile phone terminal device according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Gate electrode, 3 ... Gate insulating film, 6 ... Interlayer insulating film, 7 ... First wiring, 8 ...
・ Planarization film, 9 ... Reflection film, 10 ... Second wiring

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09F 9/30 349 G09F 9/30 349D 5F110 H01L 21/3205 H01L 21/88 A 29/786 M 29/78 612C 619B 619A F-term (reference) 2H088 EA22 EA27 HA02 HA06 HA08 HA21 MA20 2H091 FA14Y GA02 GA11 GA13 GA16 LA30 2H092 HA05 JA46 JB24 JB26 JB33 JB35 JB56 NA28 RA10 5C094 AA04 AE03 BA01 EA03 FA02 FB12 GB10 5F033 GG04 HH08 HH11 HH14 HH18 HH20 JJ01 JJ08 JJ11 JJ14 JJ18 JJ20 KK08 KK11 KK18 KK20 MM05 MM08 PP15 QQ08 QQ09 QQ37 RR04 RR25 SS22 UU04 VV02 A10 BB05A04 XXV XXA FF29 GG02 GG13 GG44 HJ01 HJ12 HJ13 HL02 HL03 HL04 HL06 HL11 HL12 HL23 HM15 HM19 NN02 NN12 NN23 NN27 NN35 NN36 NN41 NN44 NN45 NN46 NN47 NN73 PP03 QQ01 QQ12

Claims (36)

[Claims] 1. A pixel array comprising pixels arranged in a matrix and reflecting light incident from the outside for each pixel, the pixel array comprising a plurality of thin film transistors and a first wiring connecting these. A thin-film semiconductor device comprising: a driving circuit section for driving an array section; and an insulating substrate integrally formed with the pixel array section and the driving circuit section, wherein the pixel array section is incident from outside. A thin film semiconductor device, comprising: a reflection film made of a metal material for reflecting light; wherein the drive circuit section includes a second wiring formed of the same metal material as the reflection film. 2. The thin film semiconductor device according to claim 1, wherein said second wiring is laminated on said first wiring. 3. The second wiring is laminated on the first wiring via an insulating film, and is electrically connected to the first wiring via a contact hole opened in the insulating film. 3. The thin film semiconductor device according to claim 2, wherein: 4. The method according to claim 1, wherein the first wiring is made of a laminated material or alloy material mainly composed of aluminum or copper, and the second wiring is made of a laminated material or alloy material mainly composed of aluminum or silver. The thin-film semiconductor device according to claim 1. 5. The thin film semiconductor device according to claim 1, wherein said second wiring is wider than said first wiring. 6. The thin film semiconductor device according to claim 1, wherein said second wiring is covered with a protective film. 7. A pixel array portion, which is composed of pixels arranged in a matrix and reflects an incoming light from outside to display an image by each pixel, and a plurality of thin film transistors and a first wiring connecting these. A reflective display device comprising: a driving circuit unit configured to drive the pixel array unit; and an insulating substrate integrally formed with the pixel array unit and the driving circuit unit, wherein the pixel array unit is A reflection film made of a metal material for reflecting light incident from the outside, wherein the drive circuit unit includes a second wiring formed of the same metal material as the reflection film. Type display device. 8. The reflection type display device according to claim 7, wherein said second wiring is laminated on said first wiring. 9. The second wiring is laminated on the first wiring via an insulating film, and is electrically connected to the first wiring via a contact hole opened in the insulating film. 9. The reflection type display device according to claim 8, wherein: 10. The method according to claim 1, wherein the first wiring is made of a laminated material or alloy material mainly composed of aluminum or copper, and the second wiring is made of a laminated material or alloy material mainly composed of aluminum or silver. The reflective display device according to claim 7. 11. The reflective display device according to claim 7, wherein said second wiring is wider than said first wiring. 12. The reflection type display device according to claim 7, wherein said second wiring is covered with a protective film. 13. A step of forming, on an insulating substrate, a pixel array portion composed of pixels arranged in a matrix and reflecting light incident from outside for each pixel, and a step of connecting a plurality of thin film transistors to each other. Forming a driving circuit unit for driving the pixel array unit integrally with the substrate, the driving circuit unit being formed on the substrate. Forming a reflective film made of a metal material to reflect the reflected light, and forming a second wiring in the drive circuit section using the same metal material as the reflective film. Method. 14. The method according to claim 13, wherein the second wiring is laminated on the first wiring. 15. The semiconductor device according to claim 15, wherein the second wiring is stacked on the first wiring via an insulating film, and is electrically connected to the first wiring via a contact hole opened in the insulating film. The method for manufacturing a thin film semiconductor device according to claim 14, wherein 16. The method according to claim 16, wherein the first wiring is formed of a laminated material or alloy material mainly composed of aluminum or copper, and the second wiring is formed of a laminated material or alloy material mainly composed of aluminum or silver. The method for manufacturing a thin film semiconductor device according to claim 13, wherein: 17. The method according to claim 13, wherein the second wiring is formed wider than the first wiring. 18. The method according to claim 13, wherein the second wiring is covered with a protective film. 19. A step of forming, on an insulating substrate, a pixel array portion composed of pixels arranged in a matrix and displaying an image by reflecting light incident from outside on each pixel, and a plurality of thin film transistors and Forming a driving circuit portion for driving the pixel array portion integrally with the substrate, the driving circuit portion being configured with a first wiring connecting the pixel array portion to the substrate. Is characterized in that a reflection film made of a metal material is formed in order to reflect light incident from the outside, and a second wiring is formed in the drive circuit portion using the same metal material as the reflection film. A method for manufacturing a reflective display device. 20. The method according to claim 19, wherein the second wiring is laminated on the first wiring. 21. The second wiring is laminated on the first wiring via an insulating film, and is electrically connected to the first wiring via a contact hole opened in the insulating film. The method for manufacturing a reflective display device according to claim 20, wherein 22. The method according to claim 19, wherein the first wiring is formed of a laminated material or alloy material mainly composed of aluminum or copper, and the second wiring is formed of a laminated material or alloy material mainly composed of aluminum or silver. The method of manufacturing a reflective display device according to claim 19, wherein: 23. The method according to claim 19, wherein the second wiring is formed wider than the first wiring. 24. The method according to claim 19, wherein the second wiring is covered with a protective film. 25. A portable information terminal device integrally incorporating an operation unit for inputting an instruction, a processing unit for processing information in accordance with the instruction, and a display unit for displaying the processed information, The display unit is configured by a pixel array configured of pixels arranged in a matrix and displaying an image by reflecting light incident from outside on each pixel, a plurality of thin film transistors, and a first wiring connecting these. A driving circuit for driving the pixel array, and an insulating substrate integrally formed with the pixel array and the driving circuit. The pixel array is made of a metal material for reflecting light incident from outside. A portable information terminal device, comprising: a reflection film comprising: a second wiring formed of the same metal material as the reflection film. 26. The portable information terminal device according to claim 25, wherein the second wiring is stacked on the first wiring. 27. The second wiring is laminated on the first wiring via an insulating film, and is electrically connected to the first wiring via a contact hole opened in the insulating film. 27. The portable information terminal device according to claim 26, wherein: 28. The method according to claim 28, wherein the first wiring is made of a laminated material or alloy material mainly composed of aluminum or copper, and the second wiring is made of a laminated material or alloy material mainly composed of aluminum or silver. 26. The portable information terminal device according to claim 25, wherein: 29. The portable information terminal device according to claim 25, wherein said second wiring is wider than said first wiring. 30. The portable information terminal device according to claim 25, wherein the second wiring is covered with a protective film. 31. An operation unit for performing operations relating to outgoing and incoming calls, a communication unit for enabling a telephone call in accordance with the operations, and a display unit for displaying at least information relating to the operations are integrally incorporated. In the mobile phone terminal device, the display unit includes a pixel array configured of pixels arranged in a matrix and displaying an image by reflecting light incident from outside on each pixel, and a plurality of thin film transistors and connecting these. And a drive circuit configured to drive the pixel array, and an insulating substrate integrally formed with the pixel array and the drive circuit, wherein the pixel array is incident from the outside. A mobile phone terminal device, comprising: a reflection film made of a metal material for reflecting light; wherein the driving circuit includes a second wiring formed of the same metal material as the reflection film. 32. The mobile phone terminal device according to claim 31, wherein the second wiring is laminated on the first wiring. 33. The second wiring is laminated on the first wiring via an insulating film, and is electrically connected to the first wiring via a contact hole opened in the insulating film. 33. The mobile phone terminal device according to claim 32, wherein: 34. The first wiring is made of a laminated material or an alloy material mainly composed of aluminum or copper, and the second wiring is made of a laminated material or an alloy material mainly composed of aluminum or silver. 32. The mobile phone terminal device according to claim 31, wherein: 35. The mobile phone terminal device according to claim 31, wherein the second wiring is wider than the first wiring. 36. The mobile phone terminal device according to claim 31, wherein the second wiring is covered with a protective film.