JP3672084B2 - Display device, liquid crystal display device and integrated circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device formed using a thin film transistor.
[0002]
[Prior art]
As a display for office automation equipment or the like, a flat display is attracting attention instead of a CRT, and the expectation for an increase in area is particularly strong. In addition, wall-mounted TVs are being developed at a rapid pace as other applications of flat displays. In addition, the demand for color display and high definition of flat displays has been considerably increased.
[0003]
A liquid crystal display device is known as a typical example of this flat display. In this method, an electric field is applied to the liquid crystal composition held between a pair of glass substrates with an electrode interposed therebetween to change the state of the liquid crystal composition, and display is performed using the difference in this state. Some of them are provided with a thin film transistor (hereinafter referred to as TFT) and other switching elements for driving the liquid crystal, or simply have a matrix configuration. In any case, a driver circuit for sending a signal for driving the liquid crystal to each wiring in the vertical and horizontal (X, Y) directions is provided around the display.
[0004]
This driver circuit is usually composed of a single crystal silicon MOS integrated circuit (IC). This IC is provided with a pad electrode corresponding to each display electrode, and a printed circuit board is interposed between the two. First, the pad electrode of the IC and the printed circuit board are connected, and then the printed circuit board and the display are connected. It was. This printed circuit board is an insulating board made of glass epoxy or paper epoxy, or a board made of flexible plastic, and the area occupied by the printed board is equal to or larger than that of the display. Similarly, the volume has to be considerably increased.
[0005]
[Problems to be solved by the invention]
Such a conventional display has the following disadvantages due to the configuration as described above.
[0006]
That is, (1) since the same number of connections as the number of display electrodes or source (drain) wirings or gate wirings in the X direction and Y direction of the matrix wiring are made with the printed circuit board, each connectionable in terms of mounting technology A high-definition display cannot be manufactured due to a limitation in the interval between the connecting portions.
[0007]
(2) In addition to the display main body, a printed circuit board, an IC and connection wiring are required, and the required area and required volume are several times that of the display main body.
[0008]
(3) There are many connection points between the display main body and the printed circuit board and between the printed circuit board and the IC, and since the weight is considerable, an excessive force is applied to the connection part, and the connection reliability is low.
[0009]
On the other hand, as a method for solving such a drawback, it has been proposed that in a display device using a display, particularly an active element as a switching element, the active element and the peripheral circuit are formed of TFTs on the same substrate. However, according to this configuration, the above-mentioned three drawbacks can be almost solved, but another problem as described below has newly occurred.
[0010]
(4) Since the peripheral circuit other than the active elements is made into TFTs, the number of elements formed on the same substrate is increased and the manufacturing yield of TFTs is lowered. Therefore, the manufacturing yield of the display has also decreased.
[0011]
(5) The peripheral circuit portion has a very complicated element structure as compared with the element structure of the active element portion. Accordingly, the circuit pattern becomes complicated, the manufacturing process technology becomes more sophisticated, and the cost increases. Naturally, the number of multilayer wiring portions increased, resulting in an increase in the number of process steps and a decrease in TFT manufacturing yield.
[0012]
(6) Since the transistors constituting the peripheral circuit are required to have a high response speed, a polycrystalline semiconductor is usually used. Therefore, in order to polycrystallize the semiconductor layer, a high temperature treatment is required and an expensive quartz substrate or the like has to be used.
[0013]
[Means for Solving the Problems]
The present invention relates to a liquid crystal display device that solves the six problems as described above in an appropriate balance, is low in cost, and has a high manufacturing yield.
[0014]
According to the present invention,
A pixel matrix in which a plurality of TFTs are arranged in a matrix;
A plurality of data lines connected to the pixel matrix;
A plurality of scanning lines connected to the pixel matrix;
A first peripheral circuit for driving an odd-numbered data line among the plurality of data lines;
A second peripheral circuit for driving an even-numbered data line among the plurality of data lines;
A third peripheral circuit for driving the plurality of scanning lines;
An electro-optical device is provided.
[0015]
According to the present invention,
A pixel matrix in which a plurality of TFTs are arranged in a matrix;
A plurality of data lines connected to the pixel matrix;
A plurality of scanning lines connected to the pixel matrix;
A first peripheral circuit for driving an odd-numbered data line among the plurality of data lines;
A second peripheral circuit for driving an even-numbered data line among the plurality of data lines;
A third peripheral circuit for driving the plurality of scanning lines;
An electro-optical device comprising:
An electro-optical device is provided in which each of the first peripheral circuit, the second peripheral circuit, and the third peripheral circuit includes a circuit having a TFT and an IC.
[0016]
According to the present invention,
A pixel matrix in which a plurality of TFTs are arranged in a matrix;
A plurality of data lines connected to the pixel matrix;
A plurality of scanning lines connected to the pixel matrix;
A first peripheral circuit for driving an odd-numbered data line among the plurality of data lines;
A second peripheral circuit for driving an even-numbered data line among the plurality of data lines;
A third peripheral circuit for driving the plurality of scanning lines;
An electro-optical device comprising:
An electro-optical device is provided in which the first peripheral circuit, the second peripheral circuit, and the third peripheral circuit each include an analog switch array having a TFT and an IC.
[0017]
That is, a first substrate on which a pixel matrix having a plurality of gate lines, a plurality of source (drain) lines, and a thin film transistor is formed, a second substrate disposed opposite to the first substrate, and the pair of substrates An electro-optical device comprising a liquid crystal composition held therebetween, wherein at least some of peripheral circuits connected to a matrix wiring in the X or Y direction formed on the first substrate Is a thin film transistor having a structure similar to that of the active element connected to the pixel, and the remaining peripheral circuits are constituted by a semiconductor chip.
[0018]
In addition, the connection between the IC and the substrate as the remaining peripheral circuit which is not made into TFT is provided on the substrate directly, and the COG method for connecting each connection terminal or each IC chip on a flexible organic resin substrate. And the TAB method of connecting the resin substrate and the display substrate.
[0019]
That is, the present invention does not convert all the peripheral circuits of the liquid crystal display device into TFTs, but only the simple part of the element structure, only the functional part with a small number of elements, or only the circuit part where a general-purpose IC is difficult to obtain. In this case, only the high-cost portion of the IC can be made into a TFT, thereby improving the manufacturing yield of the liquid crystal display device and reducing the manufacturing cost.
[0020]
In addition, by forming a part of the peripheral circuit as a TFT, the number of external ICs, which conventionally required a considerable number, can be reduced, and the manufacturing cost can be reduced.
[0021]
Furthermore, if a complementary structure (CTFT) thin film transistor in which the active element and the peripheral circuit are made by the same process, the pixel driving capability is improved, redundancy can be given to the peripheral circuit, and a liquid crystal display with a margin. The device could be driven.
[0022]
In addition, if all the peripheral circuits are made into TFTs, it is necessary to increase the size of the display substrate in both the X direction and the Y direction, which increases the area occupied by the entire display device. Just by making the substrate larger, it is possible to easily adapt to the external dimensions of the computer or device that uses the display device, and to realize a display device with a small area and volume.
[0023]
Sophisticated fabrication techniques are required to make TFTs in parts that have complex element structures in peripheral circuits, such as element structures that require multilayer wiring and parts that have amplifier functions. By using a TFT, a conventional IC can be used for a technically difficult part, and a simple element structure or a simple function part can be converted to a TFT, and a display device can be realized at a low cost and a high yield.
[0024]
Further, by forming only a part of the TFTs, the number of thin film transistors in the peripheral circuit portion can be considerably reduced. If the functions of the peripheral circuits in the X direction and the Y direction are simply the same, the number is almost half. Thus, by reducing the number of TFT elements, it is possible to improve the manufacturing yield of the substrate and realize a display device that can reduce the area and volume of the substrate at low cost.
[0025]
Furthermore, the semiconductor layer used for TFTs can be manufactured at low temperature by using a semi-amorphous semiconductor of a new concept instead of the polycrystalline or amorphous semiconductor conventionally used, and the carrier mobility can be reduced. A very large TFT with a high response speed can be realized.
[0026]
This semi-amorphous semiconductor is obtained by performing thermal crystallization treatment after film formation by LPCVD, sputtering, PCVD, or the like, and will be described below by taking sputtering as an example.
[0027]
That is, when a single crystal silicon semiconductor is used as a target in sputtering and sputtering is performed with a mixed gas of hydrogen and argon, the atomic silicon is separated from the target by sputtering (impact) of heavy atoms of argon and has a surface to be formed. Let's fly on the substrate. At the same time, a lump of tens to hundreds of thousands of atoms is separated from the target as a cluster and flies to the formation surface.
[0028]
During this flight, hydrogen is bonded to the silicon dangling bonds around the outer periphery of the cluster, and in a bonded state, it is formed as a relatively highly ordered region on the formation surface.
That is, a state of a mixture of a highly ordered cluster having pure Si-H bonds and pure amorphous silicon is realized on the film forming surface. By heat-treating this in a non-oxidizing gas at 450 ° C. to 700 ° C., Si—H bonds in the outer periphery of the cluster react with other Si—H bonds to form Si—Si bonds.
[0029]
As this bond pulls together, highly ordered clusters attempt to shift phase to a more highly ordered state, ie crystallization. However, between adjacent clusters, Si-Si bonded to each other pulls between the clusters. As a result, the crystal has lattice distortion, and the crystal peak in laser Raman is measured by shifting to a lower wave number side than 520 cm ⁻¹ of the single crystal.
[0030]
Further, since the Si—Si bonds between the clusters anchor each other, the energy bands in each cluster can be electrically coupled to each other via the anchoring point. Therefore, it is fundamentally different from polycrystalline silicon in which the crystal grain boundary functions as a carrier barrier, and the carrier mobility can be 10 to 200 cm ² / V Sec.
[0031]
In other words, a semi-amorphous semiconductor based on such a definition can be expected to have a state of being substantially free of crystal grain boundaries while having apparent crystallinity. Of course, when the crystallization is accompanied by crystal growth of 1000 ° C. or higher, not the intermediate temperature annealing of 450 ° C. to 700 ° C. in the case of the silicon semiconductor, this crystal growth causes oxygen or the like in the film to become grain boundaries. Fold it to make a barrier. This is a material (polycrystal) having the same crystal and grain boundary as the single crystal.
[0032]
Further, when the degree of anchoring between clusters in the semiconductor is increased, the carrier mobility is further increased. For this purpose, when the amount of oxygen in the film is set to 7 × 10 ¹⁹ cm ^−3, preferably 1 × 10 ¹⁹ cm ⁻³ or less, crystallization can be performed at a temperature lower than 600 ° C., and high carriers are used. Mobility can be obtained.
[0033]
[Example 1]
In this embodiment, description will be made using a liquid crystal display device having a circuit configuration of m × n as shown in FIG. That is, only the analog switch array circuit portion 1 among the peripheral circuit portions connected to the X-direction wiring in FIG. 1 is made into a TFT 5 like the active element provided in the pixel 6 and the peripheral circuit connected to the Y-direction wiring. As for the portion, only the analog switch array circuit portion 2 is made into a TFT, and the other peripheral circuit portions are IC4, which are connected to the substrate by the COG method. Here, the peripheral circuit portion formed as a TFT is formed as a CTFT (complementary structure) in the same manner as the active element provided in the pixel.
[0034]
An arrangement configuration of actual electrodes and the like corresponding to this circuit configuration is shown in FIG. FIG. 2 shows only a portion corresponding to 2 × 2 for the sake of simplicity.
[0035]
First, a method for manufacturing a TFT on a liquid crystal display device used in this embodiment will be described with reference to FIGS. In FIG. 3A, a silicon oxide film as a blocking layer 51 is formed on a glass 50 that can withstand a heat treatment of an inexpensive 700.degree. Fabricate to a thickness of ~ 3000 mm. The process conditions were an oxygen 100% atmosphere, a film forming temperature of 15 ° C., an output of 400 to 800 W, and a pressure of 0.5 Pa. The film formation rate using quartz or single crystal silicon for the target was 30 to 100 cm / min.
[0036]
A silicon film was formed thereon by LPCVD (low pressure vapor phase) method, sputtering method or plasma CVD method. When forming by a low pressure vapor phase method, disilane (Si ₂ H ₆ ) or trisilane (Si ₃ H ₈ ) is supplied to a CVD apparatus at 450 to 550 ° C., for example, 530 ° C., which is 100 to 200 ° C. lower than the crystallization temperature. A film was formed. The pressure in the reactor was 30 to 300 Pa. The film formation rate was 50 to 250 cm / min. In order to control the threshold voltage (Vth) of NTFT and PTFT to be approximately the same, boron may be added at a concentration of 1 × 10 ¹⁵ to 1 × 10 ¹⁸ cm ⁻³ using diborane during film formation. .
[0037]
When the sputtering method was used, the back pressure before sputtering was set to 1 × 10 ⁻⁵ Pa or less, the target was single crystal silicon, and the atmosphere was mixed with 20 to 80% hydrogen in argon. For example, 20% argon and 80% hydrogen. The film forming temperature was 150 ° C., the frequency was 13.56 MHz, the sputtering output was 400 to 800 W, and the pressure was 0.5 Pa.
[0038]
When the silicon film is formed by the plasma CVD method, the temperature is set to 300 ° C., for example, and monosilane (SiH 4) or disilane (Si ₂ H ₆ ) is used. These were introduced into a PCVD apparatus, and a high frequency power of 13.56 MHz was applied to form a film.
[0039]
The film formed by these methods preferably has oxygen of 5 × 10 ²¹ cm ⁻³ or less. When this oxygen concentration is high, it is difficult to crystallize, and the thermal annealing temperature must be increased or the thermal annealing time must be increased. On the other hand, if the amount is too small, the leak current in the off state increases due to the backlight. Therefore, the range is 4 × 10 ¹⁹ to 4 × 10 ²¹ cm ⁻³ . Hydrogen was 4 × 10 ²⁰ cm ⁻³ , and compared with silicon 4 × 10 ²² cm ⁻³ , it was 1 atomic%. Further, in order to further promote crystallization with respect to the source and drain, the oxygen concentration is set to 7 × 10 ¹⁹ cm ⁻³ or less, preferably 1 × 10 ¹⁹ cm ⁻³ or less, and the channel formation region of the TFT constituting the pixel is formed. In addition, oxygen may be added so as to be 5 × 10 ^{20 to} 5 × 10 ²¹ cm ⁻³ by ion implantation. At that time, since light is not irradiated to the TFTs constituting the peripheral circuit, it is effective to operate at a high frequency to reduce the mixing of oxygen and provide a higher carrier mobility.
[0040]
Next, an amorphous silicon film is formed to a thickness of 500 to 5000 mm, for example, 1500 mm, and then heated at a temperature of 450 to 700 ° C. for 12 to 70 hours in a non-oxide atmosphere, for example, in a hydrogen atmosphere. At 600 ° C. Since an amorphous silicon oxide film is formed on the surface of the substrate under the silicon film, the specific nucleus does not exist in this heat treatment, and the whole is annealed uniformly. That is, it has an amorphous structure during film formation, and hydrogen is merely mixed.
[0041]
By annealing, the silicon film shifts from an amorphous structure to a highly ordered state, and a part thereof exhibits a crystalline state. In particular, a region having a relatively high order in a state after the film formation of silicon is particularly crystallized and tends to be in a crystalline state. However, since silicon is present between these regions, the silicon atoms pull each other. When measured by laser Raman spectroscopy, a peak shifted to a lower frequency side than the peak 522 cm ⁻¹ of single crystal silicon is observed. The apparent grain size is calculated from the half-value width, which is 50 to 500 mm, like a microcrystal, but in reality, there are many regions with high crystallinity and a cluster structure. A film with a semi-amorphous structure in which silicon is bonded (anchored) can be formed.
[0042]
As a result, the coating film exhibits a state that it may be said that there is substantially no grain boundary (hereinafter referred to as GB). Since the carriers can easily move to each other through the anchored portions between the clusters, the carrier mobility is higher than that of polycrystalline silicon in which the so-called GB is clearly present. That is, hole mobility (μh) = 10 to ²⁰⁰ cm ² / VSec and electron mobility (μe) = 15 to 300 cm ² / VSec are obtained.
[0043]
On the other hand, when the film is polycrystallized by high temperature annealing at 900 to 1200 ° C. instead of annealing at the medium temperature as described above, segregation of impurities in the film occurs due to solid phase growth from the nucleus, resulting in GB. Has a large amount of impurities such as oxygen, carbon, nitrogen, and the mobility in the crystal is large, but it creates a barrier in the GB and inhibits the movement of carriers there. As a result, it is difficult to obtain a mobility of 10 cm ² / Vsec or more. That is, in this embodiment, a silicon semiconductor having a semi-amorphous or semi-crystal structure is used for the above reasons.
[0044]
In FIG. 3A, the silicon film is photoetched with the first photomask (1) to produce a PTFT region 22 (channel width 20 μm) on the right side of the drawing and an NTFT region 13 on the left side. did.
[0045]
On this, a silicon oxide film was formed as a gate insulating film to a thickness of 500 to 2000 mm, for example 1000 mm. This was performed under the same conditions as the production of the silicon oxide film as the blocking layer. During the film formation, a small amount of fluorine may be added to fix sodium ions.
[0046]
After this, a silicon film in which phosphorus enters a concentration of 1 to 5 × 10 ²¹ cm ⁻³ or a multilayer film of molybdenum (Mo), tungsten (W), MoSi 2 or WSi 2 is formed on the silicon film. Formed. This was patterned with a second photomask (2) to obtain FIG. 3 (B). A gate electrode 55 for PTFT and a gate electrode 56 for NTFT were formed. For example, the channel length was 10 μm, the gate electrode was formed with a thickness of 0.2 μm of phosphorus-silicon, and molybdenum was formed thereon with a thickness of 0.3 μm. In FIG. 3C, a photoresist 57 is formed using a photomask (3), and boron is dosed from 1 to 5 × 10 ¹⁵ cm ⁻² with respect to a source 59 drain 58 for PTFT. By ion implantation. Next, as shown in FIG. 3D, a photoresist 61 was formed using a photomask (4). As a source 64 and a drain 62 for NTFT, phosphorus was added by an ion implantation method at a dose of 1 to 5 × 10 ¹⁵ cm ⁻² .
[0047]
These were performed through the gate insulating film 54. However, in FIG. 3B, silicon oxide on the silicon film may be removed using the gate electrodes 55 and 56 as a mask, and then boron and phosphorus may be directly ion-implanted into the silicon film.
[0048]
Next, heating annealing was performed again at 600 ° C. for 10 to 50 hours. PTFT source 59 and drain 58 NTFT source 64 and drain 62 were fabricated as P + and N + by activating impurities. Under the gate electrodes 55 and 56, channel forming regions 60 and 63 are formed as semi-amorphous semiconductors.
[0049]
In this way, a C / TFT can be made without applying a temperature in all steps to 700 ° C. or higher even though it is a self-alignment method. Therefore, it is not necessary to use an expensive substrate such as quartz as a substrate material, and this process is extremely suitable for a liquid crystal display device with a large pixel.
[0050]
In this embodiment, thermal annealing was performed twice in FIGS. 3 (A) and 3 (D). However, the annealing shown in FIG. 3A may be omitted depending on the required characteristics, and both may be used as the annealing shown in FIG. 3D to shorten the manufacturing time. In FIG. 4A, the interlayer insulator 65 is formed as a silicon oxide film by the sputtering method described above. The silicon oxide film may be formed by LPCVD, photo CVD, or atmospheric pressure CVD. For example, it was formed to a thickness of 0.2 to 0.6 μm, and then an electrode window 66 was formed using a photomask (5). Further, aluminum is formed on the entire surface by sputtering, and the leads 71 and 72 and the contacts 67 and 68 are prepared using a photomask (6), and then the surface is planarized with an organic resin 69 such as translucent polyimide. Resin was applied and formed, and electrode drilling was performed again with a photomask (7).
[0051]
As shown in FIG. 4 (B), two TFTs have a complementary configuration, and the output terminal is connected to the electrode of one pixel of the liquid crystal device as a transparent electrode. Film). This was etched using a photomask (8) to form an electrode. This ITO was formed at room temperature to 150 ° C., and was achieved by oxygen at 200 to 400 ° C. or annealing in the atmosphere. Thus, PTFT 22, NTFT 13, and transparent conductive film electrode 70 were fabricated on the same glass substrate 50. The obtained TFT has PTFT mobility of 20 (cm ² / Vs), Vth of −5.9 (V), NTFT mobility of 40 (cm ² / Vs), and Vth of 5 0.0 (V).
[0052]
FIG. 2 shows the arrangement of electrodes and the like in the pixel portion of this liquid crystal display device. NTFT 13 is provided at the intersection of first scanning line 15 and data line 21, and NTFTs for other pixels are similarly provided at the intersection of first scanning line 15 and data line 14. On the other hand, PTFT is provided at the intersection of the second scanning line 18 and the data line 21. Further, NTFTs for other pixels are provided at intersections between the other adjacent first scanning lines 16 and data lines 21. A matrix configuration using such a C / TFT was provided. The NTFT 13 is connected to the first scanning line 15 through a contact at the input end of the drain 64, and the gate 56 is connected to the data line 21 in which a multilayer wiring is formed. The output end of the source 62 is connected to the electrode 17 of the pixel through a contact.
[0053]
On the other hand, the input terminal of the drain 58 is connected to the second scanning line 18 via a contact, the PTFT 22 is connected to the data line 21, and the output terminal of the source 59 is connected to the pixel electrode similarly to the NTFT via the contact. 17 is connected. Thus, between the pair of scanning lines 15 and 18 (inside), one pixel was constituted by the pixel 23 made of a transparent conductive film and the C / TFT. By repeating this structure left and right and up and down, a liquid crystal display device having a large pixel size of 640 × 480 and 1280 × 960 can be obtained by enlarging the 2 × 2 matrix.
[0054]
Thus, the CMOS configuration is provided with the NTFT 13 and PTFT 22 manufactured by the same process as the switching element.
[0055]
As described above, one substrate is completed, bonded to the other substrate by a conventional method, and STN liquid crystal is injected between the substrates. Next, IC4 is used as the remaining peripheral circuit. The IC 4 is connected to the X-direction wiring and the Y-direction wiring of the substrate by COG. This IC4 is simply connected with connection leads for supplying power and data from the outside, and there is no FPC for connection on all sides of the board. The number is considerably reduced and the reliability is improved. A liquid crystal display device was completed as described above.
[0056]
In the present embodiment, only the analog switch array part 1 of the peripheral circuits on the X direction side is converted into TFTs, and only the analog switch array part 2 of the peripheral circuits on the Y direction side is converted into TFTs, and converted into C / TFT in the same process as the switching elements. The remaining peripheral circuit portion is composed of IC4. However, it is not particularly limited to this configuration. Considering the yield when forming TFTs, problems in process technology when forming TFTs, and the like, more TFTs can be formed. Only a simple portion needs to be made into a TFT.
[0057]
In this embodiment, since a semi-amorphous semiconductor is used as the semiconductor film, the mobility is 10 times or more that of a TFT using a non-single crystal semiconductor. Therefore, it can be used sufficiently for peripheral circuit TFTs that require a high response speed, and the TFTs in the peripheral circuit part need not be specially crystallized as in the prior art, and are produced in the same process as the active element. I was able to.
[0058]
In addition, since the active element connected to the liquid crystal pixel has a C / TFT configuration, the operation margin is expanded, the pixel potential does not fluctuate, and a constant display level can be secured. In particular, there was an advantage such as no noticeable defect display capital.
[0059]
[Example 2]
FIG. 5 shows a schematic external view of the liquid crystal display device of this example. The basic circuit and the like are exactly the same as in the first embodiment. In FIG. 5, in the peripheral circuit connected to the wiring in the Y direction, the IC is formed directly on the substrate by the COG method. The IC 4 is provided separately on the upper and lower portions of the substrate.
[0060]
In this case, the connection between the pad electrode of IC4 and the Y-direction wiring can be made narrower than the case where the IC is formed only on one side. Therefore, it has the feature that a higher definition display pixel can be designed. Further, since the IC is provided on the substrate, the volume is hardly increased, and a thinner liquid crystal display device can be provided.
[0061]
In the above embodiment, the TFT of the active element has a CMOS structure. However, the present invention is not particularly limited to this structure, and may be composed of only NTFT and PTFT. The number of elements will increase.
[0062]
In addition, the TFT is formed not only on one side where the TFT is formed on the substrate but also on the other side of the X-direction or Y-direction. As a result, the TFT manufacturing yield was improved.
[0063]
【The invention's effect】
According to the present invention, it is no longer possible to increase the definition of a liquid crystal display due to restrictions on external connection technology. In addition, since unnecessary connection between the X-direction wiring or the Y-direction wiring and the external peripheral circuit can be reduced as much as possible, the reliability at the connection portion is improved.
[0064]
Since only some peripheral circuits are made into TFTs, the area occupied by the display substrate itself can be reduced, and the substrate can be freely designed to have the required dimensions. Also, TFT manufacturing problems can be avoided, and only the parts with high manufacturing yield can be made into TFTs. Therefore, the manufacturing cost could be reduced.
[0065]
Since a semi-amorphous semiconductor is used as a semiconductor film used for TFT, a response speed sufficient for peripheral circuits can be obtained, and there is no special processing in the process of creating an active element, and for peripheral circuits. A TFT could be created at the same time.
[0066]
In the present invention, complementary TFTs are connected to each pixel in a matrix, so that (1) the threshold value is clarified, (2) the switching speed is increased, (3) the operation margin is expanded, and (4) the defective TFT is connected. Can be compensated to some extent even if there are some. {Circle around (5)} The number of photomasks required for fabrication is only increased twice compared to the conventional example of NTFT alone. (6) Since the carrier mobility is more than 10 times larger than when amorphous silicon is used, the size of the TFT can be reduced, and even if two TFTs are provided in one pixel, the aperture ratio is almost reduced. Absent. It has many features.
[0067]
Therefore, compared to the conventional active TFT liquid crystal device using only NTFT, several stages of production yield and screen vividness can be achieved.
[Brief description of the drawings]
FIG. 1 is a diagram showing a liquid crystal display device having a circuit configuration of m × n.
FIG. 2 is a diagram showing a state of arrangement of pixel portions of a liquid crystal display device.
FIG. 3 is a diagram showing an outline of a manufacturing process of a TFT.
FIG. 4 is a diagram showing an outline of a manufacturing process of a TFT.
FIG. 5 is a diagram showing another embodiment.
[Explanation of symbols]
1, 2 ... Peripheral circuit 4 ... IC
5 ... TFT peripheral circuit 6 ... Pixel 13 ... NTFT
22 ... PTFT

Claims (4)

A display device having a pixel portion and a drive circuit portion electrically connected to the pixel portion on a blocking layer formed on a glass substrate that can withstand heat treatment at 700 ° C. or lower ,
The pixel portion has a thin film transistor,
The driving circuit portion includes a circuit other than the analog switch array composed of analog switch array and an IC chip formed of thin film transistors,
Thin film transistors of the pixel portion and the analog switch array includes a semiconductor layer of the oxygen concentration of 7 × ¹⁰ 19 ^{cm -3} or less,
An interlayer insulating film formed on the pixel portion and the thin film transistor of the analog switch array;
A wiring formed on the interlayer insulating film and connected to one of a source region or a drain region of a thin film transistor of the pixel portion;
A wiring formed on the interlayer insulating film and connected to a source region or a drain region of a thin film transistor of the analog switch array;
A contact connected to the other of the source region or drain region of the thin film transistor of the pixel portion;
A planarization film formed on a wiring connected to one of a source region or a drain region of the thin film transistor of the pixel portion and a wiring connected to a source region or a drain region of the thin film transistor of the analog switch array;
A pixel electrode formed on the planarization film,
The pixel electrode is connected to the contact through a hole formed in the planarization film,
Circuits other than the analog switch array made of the IC chip are mounted on the glass substrate on which the blocking layer is formed and are electrically connected to the analog switch array. A display device having a pixel portion and a drive circuit portion electrically connected to the pixel portion on a blocking layer formed on a glass substrate that can withstand heat treatment at 700 ° C. or lower ,
The pixel portion has a thin film transistor,
The driving circuit portion includes a circuit other than the analog switch array composed of analog switch array and an IC chip formed of thin film transistors,
Thin film transistors of the pixel portion and the analog switch array includes a semiconductor layer of the oxygen concentration of 7 × ¹⁰ 19 ^{cm -3} or less,
An interlayer insulating film formed on the pixel portion and the thin film transistor of the analog switch array;
A wiring formed on the interlayer insulating film and connected to one of a source region or a drain region of a thin film transistor of the pixel portion;
A wiring formed on the interlayer insulating film and connected to a source region or a drain region of a thin film transistor of the analog switch array;
A contact connected to the other of the source region or drain region of the thin film transistor of the pixel portion;
A planarization film formed on a wiring connected to one of a source region or a drain region of the thin film transistor of the pixel portion and a wiring connected to a source region or a drain region of the thin film transistor of the analog switch array;
A pixel electrode formed on the planarization film,
The pixel electrode is connected to the contact through a hole formed in the planarization film,
Circuits other than the analog switch array made of the IC chip are electrically connected to the analog switch array using a COG method. Thin film transistors and thin film transistors of the analog switch array of the pixel portion, the display device according to claim 1 or 2, characterized in that both a top gate type. Thin film transistors and thin film transistors of the analog switch array of the pixel portion, the display according to any one of claims 1 to 3, characterized in that it each have a gate insulating film containing fluorine apparatus.

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