JP2002062856A - Display device and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device enabling to automatically adjust brightness according to ambient brightness. SOLUTION: To solve the above problem, the configuration of this invention is characterized by having a γ-correction circuit for converting a video signal voltage into a driving voltage for displaying a gradation, and an optical sensor for controlling an input-output characteristic of the γ-correction circuit according to the ambient brightness. In this case, the γ-correction circuit for converting the video signal voltage into a driving voltage for a gradation display is formed on a 1st substrate, the optical sensor for controlling the input-output voltage characteristic of the γ-correction circuit according to the ambient brightness is formed on a 2nd substrate, and the 2nd substrate is fixed on the 1st substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device capable of adjusting the brightness of a display screen according to the brightness of the surroundings, and a method of manufacturing the same.

[0002]

2. Description of the Related Art A thin film transistor (hereinafter referred to as TF) is formed on a substrate.
The technology for forming T has been greatly advanced, and its application to active matrix display devices has been advanced. Conventionally, an active matrix display device that has been put into practical use by a TFT using an amorphous silicon film has required a driver IC. However, a TFT using a polycrystalline silicon film can operate at a high driving frequency,
It is possible to integrally form the TFT of the pixel portion and the TFT of the drive circuit on a substrate.

An active matrix type display device in which a drive circuit is integrally formed on a substrate has various advantages such as reduction in cost, downsizing of the device, and improvement in production yield by forming various circuits such as a shift register and a sampling circuit. It has been noted that benefits can be obtained.

In an active matrix display device, TFTs are arranged in tens to millions of pixels, and
Individual electrodes (pixel electrodes) are provided for each of the TFTs. In the case of a liquid crystal display device, liquid crystal is sealed between an element substrate on which a TFT is formed and a counter substrate on which a common electrode is formed. Then, a kind of capacitor using liquid crystal as a dielectric between the individual electrode and the common electrode is formed. The operation of the liquid crystal display device controls the voltage applied to each pixel by the switching function of the TFT, drives the liquid crystal by accumulating electric charges in this capacitor, and adjusts the amount of light transmitted through the liquid crystal to display an image. It has a mechanism. As a light source, there is a reflection type liquid crystal display device using external light, but a liquid crystal display device using a backlight or a front light is generally used.

On the other hand, a display device has been developed in which a light emitting element is provided for each pixel, and the blinking of the light emitting element is controlled by a TFT to display an image. Since the light emitting element uses electroluminescence (hereinafter, referred to as EL), this type of display device is an EL device.
It is also called a display device. In an active matrix type EL display device using a TFT, a switching TFT (hereinafter, referred to as a switching TFT) is provided for each pixel, and a TFT (hereinafter, referred to as a current control TFT) that performs current control by the switching TFT is provided. The EL layer (indicating an organic compound layer including a light emitting layer) is operated to emit light. For example, there is an EL display device described in JP-A-10-189252.

As described above, in the active matrix type display device, whether the external light is used or the self-luminous light is used, the intensity of the screen brightness is controlled by the TFT by the input voltage based on the video signal. It is designed to display images.

[0007]

However, many of the conventional display devices have a fixed input voltage characteristic for displaying an image, and take into account that the required maximum luminance of the display device varies depending on the surrounding environment. There was not enough. When the surrounding environment is dark at night, it can be recognized even if it does not have the same brightness as when it is used outdoors during the day, but it is dazzling to the user because the brightness is not adjusted. Often, visibility was impaired.

Of course, a method has been proposed in which the brightness of the screen is adjusted by detecting the ambient brightness with a sensor. A photodiode, a phototransistor, or the like is used as a sensor for detecting brightness, that is, illuminance. But,
When these sensors are mounted as individual components on a display device, an extra area is required. External light is scattered by objects around the display device and enters the optical sensor from various angles. As a result, there is a problem that a difference occurs between the correction of the surrounding brightness and the brightness.

Further, depending on the type of the sensor, in order to match the human visibility with the spectral sensitivity characteristics of the sensor,
Unless an optical filter is attached, there is a problem that an error occurs in correction. For example, a sensor using single crystal silicon has a spectral sensitivity spread in an infrared light region, and therefore, it is necessary to provide a visibility correction filter in order to accurately correct brightness. For this reason, the display device is inevitably increased in size.

[0010] In order to solve the above problems, the present invention provides:
It is an object of the present invention to provide a display device that can automatically adjust brightness according to the surrounding brightness and that can appropriately adjust brightness in response to a change in surrounding brightness felt by a human. .

[0011]

According to a configuration of the present invention for solving the above-mentioned problems, an output line of a gamma correction circuit is connected to a video signal processing circuit in an active matrix type display device. The γ correction circuit inputs a signal for changing the apparent luminance of the pixel according to the ambient brightness to the video signal processing circuit based on the output signal from the optical sensor. A plurality of optical sensors are provided. By providing a plurality of optical sensors around the pixel part of the active matrix display device, it is scattered by surrounding objects and detects the light intensity incident on each optical sensor from various angles and it is appropriate to balance it Correction can be made. Note that a correction circuit other than the γ correction circuit can be used.

In this case, a gamma correction circuit for converting the video signal voltage into a drive voltage for gradation display is formed on the first substrate, and controls the input / output voltage characteristics of the gamma correction circuit in accordance with ambient brightness. It is preferable that an optical sensor for performing the operation is formed on a second substrate, and the second substrate is fixed to the first substrate.

According to another aspect of the present invention, there are provided a plurality of optical sensors provided on an outer peripheral portion of a substrate on which a pixel portion is formed, a source follower circuit connected to the plurality of optical sensors, and a connection to the source follower circuit. It has a γ correction circuit, a video signal amplification circuit connected to the γ correction circuit, a source signal line driving circuit connected to the video signal amplification circuit, and a pixel unit connected to the source signal line driving circuit. As the optical sensor used in the present invention, an optical sensor containing amorphous silicon in a photoelectric conversion layer is preferably used.

In this optical sensor, p-type and n-type photoelectric conversion layers are used.
An I-type high-resistance amorphous silicon film is sandwiched between a type amorphous semiconductor film and a microcrystalline semiconductor film. Further, it has a structure in which a transparent electrode is formed on the light incident side and a metal electrode is formed on the opposite side. The optical sensor having such a structure has a peak in the spectral sensitivity characteristic at 500 to 600 nm,
It is close to human luminosity characteristics. Therefore, it is not necessary to use a visibility correction filter.

In another aspect of the invention, a step of forming a pixel portion with a thin film transistor on a first substrate, a step of forming an optical sensor on a second substrate, and a step of forming the photosensor on the first substrate are provided. Fixing the two substrates.

In another aspect of the invention, a pixel portion, a driving circuit for the pixel portion, and a control circuit for controlling the luminance of the pixel portion are formed on a first substrate by a thin film transistor; Forming an optical sensor on the second substrate;
Fixing the second substrate to the first substrate, and electrically connecting the control circuit and the optical sensor.

The microcrystalline semiconductor film, the amorphous silicon film, and the conductive film for forming the electrodes, which constitute the optical sensor, can be formed by a plasma CVD method or a sputtering method.
These film formation methods can form a film even when the area of the substrate is increased. For example, one side is 300mm or more,
Preferably, a substrate of 1000 mm or more can be used. On the other hand, the size of the optical sensor mounted on the display device is 1 to 5 mm on one side, and by using a large substrate,
A large number of optical sensors can be taken out from one substrate.

[0018]

FIG. 1 is a block diagram showing a circuit configuration of an active matrix type display device of a digital drive system. In the pixel portion 101, a plurality of gate lines 113 extending from the gate signal line driver circuit 102 and a plurality of source lines 114 extending from the source signal line driver circuit 103 intersect, and a TFT is provided at each intersection. It is formed. A video signal processing circuit 112 for forming a digital data signal input to the pixel portion is provided.

A control circuit 100 for detecting the brightness of the surroundings and controlling the amplitude of the image signal input to the pixel portion includes a detection circuit 108 for detecting an output from the optical sensor 107 and an A / D converter.
Conversion circuit 109, arithmetic processing circuit 110, gamma correction circuit 11
Consists of one.

The optical sensor 107 has a structure in which a p-type and n-type amorphous semiconductor film or a microcrystalline semiconductor film and a pin junction in which an I-type high-resistance amorphous silicon film is sandwiched between photoelectric conversion layers. Is adopted. It has a structure in which a transparent electrode is formed on the light incident side and a metal electrode is formed on the opposite side. As described above, the optical sensor using the amorphous silicon film has a peak in the spectral sensitivity characteristic of 500 to 600 nm, which is close to the human visual sensitivity characteristic. Therefore, it is not necessary to use a visibility correction filter.

FIG. 2 is a circuit diagram for explaining the detection circuit 108. When the reset TFT 202 is turned on, a reverse bias voltage is applied to the optical sensor 201. (Hereafter, an operation in which the potential of the negative terminal of the optical sensor 201 is charged to the potential of the power supply voltage is referred to as reset.) Thereafter, the reset TFT 202 is turned off. At that time, due to the electromotive force of the optical sensor 201, the optical sensor 2 which has been charged to the potential of the power supply voltage as time passes.
The potential of the negative terminal of 01 gradually decreases due to the charge generated by the photoelectric conversion. After a certain period of time, when the switching TFT 204 is turned on, a signal is output to the output side through the amplifying TFT 203.

In this case, the amplifying TFT 203 and the switching TFT 204 operate as a so-called source follower circuit. In FIG. 2, the source follower circuit is an n-channel type T
Although shown as an example formed by FT, it is needless to say that a p-channel TFT can also be formed. Amplifier side power line 20
5 is supplied with a power supply voltage Vdd. The bias-side power supply line 206 is supplied with a reference potential of 0V. TF for amplification
The drain side terminal of T203 is connected to the amplification side power supply line,
The source side terminal is connected to the drain terminal of the switching TFT 204. The source terminal of the switching TFT 204 is connected to the bias power line 206. The gate terminal of the switching TFT 204 has a bias voltage Vb
Is applied, and a bias current Ib flows through this TFT. The switching TFT 204 basically operates as a constant current source. The input voltage Vin is applied to the gate terminal of the amplifying TFT 203, and the source terminal becomes the output terminal. The input / output relationship of this source follower circuit is as follows: Vout = Vin−
Vb.

The output voltage Vout is supplied to the A / D conversion circuit 10
9 to convert to a digital signal. The digital signal is converted from a signal input to the arithmetic processing circuit 110 into a correction signal for correcting the luminance of an image based on comparison data set in advance. The gamma correction circuit 111 generates a correction voltage based on the correction signal, and its output line is connected to the video signal processing circuit 112 to output the correction voltage.

The video signal processing circuit 112 converts a video signal (a signal including image information) formed of an analog signal or a digital signal into a digital data signal for performing time-division gradation, and performs time-division gradation display. For this purpose, a timing pulse or the like necessary for this is generated and input to the source signal line driving circuit.

The video signal processing circuit 112 includes a time-division grayscale data signal generation circuit. This circuit includes a plurality of sub-frames corresponding to n-bit (n is an integer of 2 or more) one frame period. Means for dividing an address period and a sustain period in the plurality of subframe periods, and dividing the sustain period into Ts1:
Ts2: Ts3:...: Ts (n-1): Ts (n) = 2 ⁰ :
2 ^-1 : 2 ^-2 :...: 2- ^(n-2) : 2- ^(n-1) .

Next, the time division gray scale display will be described with reference to FIG. Here, a case where full color display of 2 ⁿ gradations is performed by an n-bit digital driving method will be described. First, as shown in FIG. 20, one frame period is divided into n subframe periods (SF1 to SFn). Note that a period in which all the pixels in the pixel portion display one image is referred to as one frame period. In the frame period, the oscillation frequency is 60 Hz or more, that is, 60 or more per second.
More than 60 images are displayed per second. When the number of images displayed per second becomes less than 60, flickering of the image such as flicker starts to be noticeable visually. Further, a period obtained by further dividing one frame period is referred to as a sub-frame period. As the number of gradations increases, the number of divisions in one frame period also increases, and the driving circuit must be driven at a high frequency.

One subframe period is divided into an address period (Ta) and a sustain period (Ts). The address period is a time required for inputting data to all the pixels during one subframe period, and the sustain period indicates a period in which the pixels are in an ON state (bright state).

The n sub-frame periods (SF1 to SF
n) address periods (Ta1 to Tan) respectively
Are all constant in length. The sustain periods (Ts) of SF1 to SFn are represented by Ts1 to Tsn, respectively.
And The length of the sustain period is Ts1: Ts2: T
s3: ...: Ts (n-1): Tsn = 2 ⁰ : 2 ^-1 :
2 ^-2 : ...: 2- ^(n-2) : Set so as to be 2- ^(n-1) .
However, SF1 to SFn may appear in any order. A desired gray scale display out of 2 ⁿ gray scales can be performed by the combination of the sustain periods.

The sustain period is determined based on the correction voltage from the gamma correction circuit 111, and adjusts the brightness of the image according to the surrounding brightness.

The source signal line driving circuit 103 basically includes a shift register 104, a latch A105, and a latch B106.
have. A clock pulse (CLK) and a start pulse (SP) are input to the shift register 104, and a digital data signal (Digita
l Data Signals) is input, and a latch signal (Latch Signals) is input to the latch B106. Although only one source signal line driver circuit 103 is provided in FIG. 1, a plurality of source signal line driver circuits may be provided.

The gate signal line driving circuit 102 has a shift register, a buffer, and the like (neither is shown). Note that although two gate signal line driver circuits 302a and 302b are provided in FIG. 3A, one data signal line driver circuit may be provided in this embodiment mode.

FIG. 15 is a block diagram showing a configuration of an active matrix type display device of an analog drive system. 1
21 is a source signal line driving circuit, and 102 is a gate signal line driving circuit. In this embodiment, one source signal line driving circuit and one gate signal line driving circuit are provided, but the present invention is not limited to this configuration. Two source signal line driver circuits may be provided. Further, two gate signal line driver circuits may be provided.

The source signal line driving circuit 121 has a shift register 122, a level shift 123, and a sampling circuit 124. Note that the level shift may be used as needed, and may not necessarily be used. In this embodiment, the level shift is provided between the shift register 122 and the sampling circuit 124. However, the present invention is not limited to this configuration. A configuration in which the level shift 123 is incorporated in the shift register 122 may be employed.

A clock signal (CLK) and a start pulse signal (SP) are input to the shift register 122. A sampling signal for sampling an analog signal (analog signal) is output from the shift register 122. The output sampling signal is level shift 1
23, and the potential is increased in amplitude and output. The sampling signal output from the level shift 123 is input to the sampling circuit 124. Then, the analog video display signals input to the sampling circuit 124 are respectively sampled by the sampling signals and input to the source signal lines.

The control circuit 120 for detecting the brightness of the surroundings and controlling the amplitude of the image signal input to the pixel portion includes an optical sensor 126, a detection circuit 127 for detecting the output from the optical sensor 126, an arithmetic processing circuit 128, It comprises a gamma correction circuit 129. The circuit configuration of the optical sensor 126 and the detection circuit 127 is similar to that of FIG.
Converts the signal input to the arithmetic processing circuit 128 into a correction signal for correcting the luminance of the image. The video signal processing circuit 125 adjusts the brightness by changing the amplitude of the video signal based on the correction signal.

As described above, even in the active matrix type display device of the analog drive system, the light sensor is attached, the correction voltage is changed based on the ambient brightness detected by the light sensor, and the voltage gradation is performed to perform the luminance. Adjustments can be made. Note that the configurations of the pixel portion and the driving circuit thereof shown here are merely examples, and the present invention is not limited to the configurations shown in this embodiment.

[0037]

[Embodiment 1] FIG. 3 is a schematic diagram of an active matrix type display device having an automatic brightness adjustment function. A pixel portion 301, a substrate 300 having an insulating surface,
Gate signal line driving circuits 302a and 302b, source signal line driving circuits 303a and 303b, control circuit 305, video signal processing circuit 304, input terminal 307, optical sensor 30
6 are provided. As shown in FIG. 3, a plurality of optical sensors 306 are provided on the outer periphery of the substrate 300. When a plurality of light sensors 306 are provided, fine brightness control can be performed by detecting light from various angles.

The optical sensor 306 is manufactured using a material having a photoelectric effect such as amorphous silicon. Optical sensor 30
Reference numeral 6 is manufactured on another substrate, and is outside the pixel portion 301 and the driving circuit of the substrate 300, and is attached to the outer peripheral portion of the substrate 300. In this case, the light receiving surface of the optical sensor and the image display surface of the pixel portion face in the same direction.

The pixel portion 301 is formed by arranging a plurality of pixels 308 in a matrix. The pixel 308 has a different configuration depending on the type of display device, but in any case, each pixel is provided with a TFT.

Video signal processing circuit 304 and control circuit 30
The configuration of 5 is similar to that of FIG. 1 (digital drive) or FIG. 15 (analog drive), and changes the amplitude of the video signal input to the source signal line driving circuit according to the output from the optical sensor 306 to adjust the brightness. I do. When the surroundings are bright, the amplitude of the video signal is increased to increase the brightness of the image. If dark, the opposite is true.

Pixel section 301, gate signal line drive circuit 30
2, source signal line driving circuit 303, video signal processing circuit 3
04, the control circuit 305 can be formed on the substrate 300 using a TFT.

According to the present invention, in an active matrix type display device, the brightness of the surroundings is detected by an optical sensor, and the brightness of the image display is controlled based on this information.
A plurality of optical sensors 306 are provided around the pixel unit 301 to detect light intensity incident on each optical sensor from various angles scattered by a peripheral object and to perform appropriate correction by balancing the light intensities. be able to. FIG.
The configuration of FIG. 3 is not limited to the configuration of the display device described above, and the structure of FIG. 3 is only one of preferred embodiments for implementing the present invention.

[Embodiment 2] The active matrix display device shown in FIG. 3 makes it possible to realize a liquid crystal display device or an EL display device. In this embodiment, an example in which a TFT is formed over a substrate and a liquid crystal display device is manufactured will be described.

First, as shown in FIG. 4A, a silicon oxide film is formed on a glass substrate 401 such as barium borosilicate glass represented by Corning # 7059 glass or # 1737 glass or aluminoborosilicate glass. Then, a blocking layer 402 made of an insulating film such as a silicon nitride film or a silicon oxynitride film is formed. For example, a silicon oxynitride film formed from SiH ₄ , NH ₃ , and N ₂ O by plasma CVD is formed to a thickness of 10 to 200 nm (preferably 50 to 100 nm), and an oxide film similarly formed from SiH ₄ and N ₂ O is formed. Silicon nitride film 50-200
nm (preferably 100 to 150 nm). Although the blocking layer 402 has a two-layer structure in this embodiment, the blocking layer 402 may have a single-layer structure of the insulating film or a structure in which two or more layers are stacked.

Semiconductor layers 403 to 406 divided into islands
Is to form a semiconductor film having an amorphous structure into a semiconductor film having a crystalline structure (hereinafter referred to as a crystalline semiconductor film) by heat treatment using a laser annealing method or a furnace annealing furnace. The island-shaped semiconductor layers 403 to 406 are formed to have a thickness of 25 to 80 nm (preferably 30 to 60 nm). The material of the crystalline semiconductor film is not limited, but is preferably formed of silicon or a silicon germanium (SiGe) alloy.

In order to form a crystalline semiconductor film by a laser annealing method, a pulse oscillation type or continuous emission type excimer laser, a YAG laser, or a YVO ₄ laser is used. A method is used in which laser light output from a laser oscillator is linearly condensed by an optical system and irradiated on a semiconductor film. Annealing conditions are appropriately selected by the practitioner. When an excimer laser is used, the pulse oscillation frequency is 30 Hz.
And a laser energy density of 100 to 400 mJ / cm ²
(Typically 200 to 300 mJ / cm ² ). Also, YA
When a G laser is used, the pulse oscillation frequency is set to 1 to 10 kHz using the second harmonic, and the laser energy density is set to 300 to 600 mJ / cm ² (typically 350 to 500 mJ / cm ² ).
cm ² ). Then, laser light condensed linearly with a width of 100 to 1000 μm, for example, 400 μm, is irradiated over the entire surface of the substrate, and the superposition rate (overlap rate) of the linear laser light at this time is set to 80 to 98%.

Next, a gate insulating film 407 covering the island-shaped semiconductor layers 403 to 406 is formed. Gate insulating film 40
Reference numeral 7 denotes an insulating film containing silicon having a thickness of 40 to 150 nm using a plasma CVD method or a sputtering method. In this embodiment, a silicon oxynitride film is formed with a thickness of 120 nm. Needless to say, the gate insulating film 407 is not limited to such a silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a stacked structure.

Then, a first conductive film 408a and a second conductive film 408b for forming a gate electrode are formed over the gate insulating film 407. In this embodiment, the first conductive film 408a is formed of tantalum nitride or titanium by 50 to 100 nm.
The second conductive film 408b is formed with tungsten to a thickness of 100 to 300 nm. These materials are stable even in a heat treatment at 400 to 600 ° C. in a nitrogen atmosphere, and the resistivity does not significantly increase.

Next, as shown in FIG. 4B, a mask 409 made of a resist is formed, and a first etching process for forming a gate electrode is performed. There is no limitation on the etching method, but preferably, ICP (Inductively Coupled Plas) is used.
ma: Inductively coupled plasma) etching method is used. Mixture of CF ₄ and Cl ₂ as etching gas, 0.5~2Pa,
Preferably, at a pressure of 1 Pa, 500 W of R is applied to the coil type electrode.
F (13.56 MHz) power is applied to generate plasma. 100W RF (13.56) on the substrate side (sample stage)
MHz) power is applied and a substantially negative self-bias voltage is applied. When CF ₄ and Cl ₂ are mixed, etching can be performed at substantially the same rate even in the case of a tungsten film, a tantalum nitride film, and a titanium film.

Under the above etching conditions, the end can be tapered due to the effect of the shape of the resist mask and the bias voltage applied to the substrate side. The angle of the tapered portion is set to 25 to 45 degrees. In order to perform etching without leaving a residue on the gate insulating film, the etching time may be increased by about 10 to 20%. Since the selectivity of the silicon oxynitride film to tungsten is 2 to 4 (typically 3), the exposed surface of the silicon oxynitride film is etched by about 20 to 50 nm by over-etching. Thus, the first shape conductive layers 410 to 415 (the first conductive films 410 a to 415 a and the second conductive film 410 b) including the first conductive film and the second conductive film are formed by the first etching treatment.
To 415b). Reference numeral 416 denotes a gate insulating film, and a region which is not covered with the first shape conductive layer is 20 to 50.
It is etched by about nm and becomes thin.

Then, as shown in FIG. 4C, a first doping process is performed to dope an n-type impurity (donor). The doping is performed by an ion doping method or an ion implantation method. The condition of the ion doping method is that the dose is 1 × 10 ^{13 to} 5 × 10 ¹⁴ / cm ² . As the impurity element imparting n-type, an element belonging to Group 15 of the periodic table, typically, phosphorus (P) or arsenic (As) is used. In this case, the acceleration voltage is controlled (for example, 20 to 60 keV), and the first shape conductive layer is used as a mask. Thus, the first
Of impurity regions 417 to 420 are formed. For example, the first
The impurity concentration of the n-type impurities in the impurity regions 417 to 420 is in the range of 1 × 10 ²⁰ to 1 × 10 ²¹ / cm ³ .

In the second etching process shown in FIG. 5A, similarly, using an ICP etching apparatus, CF ₄ , Cl ₂ and O ₂ are mixed in an etching gas, and a coil-type electrode is formed at a pressure of 1 Pa. A plasma is generated by supplying 500 W of RF power (13.56 MHz). 50 on the substrate side (sample stage)
RF (13.56 MHz) power of W is applied, and a lower self-bias voltage is applied than in the first etching process. Under such conditions, the tungsten film is anisotropically etched so that the tantalum nitride film or the titanium film as the first conductive layer is left. Thus, the second shape conductive layer 42
1 to 426 (first conductive films 421a to 426a and second conductive films 421b to 426b) are formed. Regions of the gate insulating film that are not covered by the second shape conductive layers 421 to 426 are further etched by about 20 to 50 nm to reduce the thickness.

Next, a second doping process is performed. An n-type impurity (donor) is doped under a condition of a higher acceleration voltage with a lower dose than in the first doping process. For example, the acceleration voltage is set to 70 to 120 keV and 1 × 10 ¹³ / cm ²
The second impurity region 42 is formed inside the first impurity region formed in the island-shaped semiconductor layer in FIG.
7 to 430 are formed. This doping is performed using the second shape conductive layers 423b to 426b as a mask for impurity elements.
Is doped so that an impurity element is added to a region below the region. This impurity region is formed in the second shape conductive layer 423.
Since a to 426a remain with substantially the same film thickness,
The difference in the concentration distribution in the direction along the conductive layer of the second shape is small, and the film is formed so as to contain an n-type impurity (donor) at a concentration of 1 × 10 ¹⁷ to 1 × 10 ¹⁹ / cm ³ .

Then, as shown in FIG. 5B, a third etching process is performed to perform an etching process on the gate insulating film. As a result, the second shape conductive layers 421a to 421a
6a is also etched, and the end portions recede and become smaller, and the third shape conductive layers 431 to 436 (the first conductive film 431) are formed.
a to 436a and second conductive films 431b to 436b) are formed. Reference numeral 437 denotes a remaining gate insulating film, which may be further etched to expose the surface of the semiconductor layer.

For a p-channel type TFT, FIG.
As shown in (C), resist masks 438 and 439 are formed, and a p-type impurity (acceptor) is doped into an island-shaped semiconductor layer forming a p-channel TFT. The p-type impurity (acceptor) is selected from elements belonging to Group 13 and typically uses boron (B). The impurity concentration of the third impurity regions 440a to 440c is 2 × 10 ²⁰ to 2 ×
It should be 10 ²¹ / cm ³ . Although phosphorus is added to the third impurity region, boron is added at a higher concentration to invert the conductivity type.

Through the above steps, an impurity region is formed in the semiconductor layer. In FIG. 5, a third shape conductive layer 433 is shown.
435 are gate electrodes, and the third shape conductive layer 43
Reference numeral 6 denotes a capacitance wiring. In addition, the third shape conductive layer 43
Reference numerals 1 and 432 form a wiring such as a source line.

Next, in FIG. 6A, first, a silicon nitride film (SiN: H) or a silicon oxynitride film (SiN:
_x O _y : H) is formed on the first insulating film 441 by plasma CV.
Formed by method D. Then, a step of activating the impurity element added to each island-shaped semiconductor layer is performed for the purpose of controlling the conductivity type. Activation is preferably performed by a thermal annealing method using a furnace annealing furnace. Alternatively, a laser annealing method or a rapid thermal annealing method (RTA method) can be applied. In the thermal annealing method, the oxygen concentration is 400 to 700 ° C. in a nitrogen atmosphere having a concentration of 1 ppm or less, preferably 0.1 ppm or less, typically 500 to 6 ° C.
In this embodiment, the heat treatment is performed at 550 ° C. for 4 hours.

Thereafter, a silicon nitride film (SiN: H) or a silicon oxynitride film (Si
N _x O _y: forming a second insulating film 442 made of H).
Then, heat treatment is performed at 350 to 500 ° C. The semiconductor film is hydrogenated with hydrogen released from the second insulating film 442.

Further, as shown in FIG. 6B, a third insulating film 443 made of an organic resin is formed to a thickness of about 1000 nm. As the organic resin film, polyimide, acrylic,
Polyimide amide or the like can be used. The advantage of using an organic resin film is that the film forming method is simple,
Since the relative permittivity is low, the parasitic capacitance can be reduced, the flatness is excellent, and the like. Note that an organic resin film other than those described above can be used. Here, it is formed by baking at 300 ° C. using a type of polyimide which is thermally polymerized after being applied to the substrate.

Next, as shown in FIG.
3. A contact hole is formed in the second insulating film 442 and the first insulating film 441, and the connection electrode 4 is formed using aluminum (Al), titanium (Ti), tantalum (Ta), or the like.
51 and source or drain wirings 444 to 447 are formed. In the pixel portion, a pixel electrode 450, a gate wiring 449, and a connection electrode 448 are formed.

In this manner, the p-channel type T
A peripheral circuit 451 including an FT 453 and an n-channel TFT 454 and a pixel portion 452 including a pixel TFT 455 and a storage capacitor 456 are formed. FIG. 6B shows only a cross-sectional view of the p-channel TFT 453 and the n-channel TFT 454 of the peripheral circuit 451.
The gate signal line driver circuit, the source signal line driver circuit, the video signal processing circuit, and the control circuit described in Embodiment 1 can be formed using FT. The circuit configuration may be appropriately determined by the practitioner.

The p-channel TFT 45 of the driving circuit 451
3 includes third impurity regions 502 to 5 functioning as a channel formation region 501 and a source region or a drain region.
04.

The n-channel type TFT 454 includes a channel formation region 505 and a second impurity region 506 (Gate Overlapped with a gate electrode formed of a third shape conductive layer 434).
apped drain: GOLD region, second impurity region 507 (Lightly Doped Drai) formed outside the gate electrode
n: LDD region) and a first impurity region 508 functioning as a source region or a drain region. The gate signal line driver circuit and the source signal line driver circuit described in Embodiment 1 can be formed using these TFTs.

The pixel TFT 455 has a channel forming region 5
09, a third shape conductive layer 435 forming a gate electrode
A second impurity region 510 (GOLD region) overlapping with the second impurity region 511 formed outside the gate electrode
(LDD region) and first impurity regions 512, 513, and 514 each functioning as a source region or a drain region. In the semiconductor film functioning as one electrode of the storage capacitor 456, impurity regions 516 and 517 and a region 515 to which an impurity is not added are formed.

In the pixel portion 452, the connection electrode 448
Accordingly, the source wiring 432 is electrically connected to the source or drain region 512 of the pixel TFT 455. The gate wiring 449 is electrically connected to the gate electrode 435. Further, the pixel electrode 450 is connected to the source or drain region 514 of the pixel TFT 455 and the impurity region 517 of the semiconductor film which is one electrode of the storage capacitor 456.

The sectional view of the pixel portion 452 in FIG. 6B corresponds to the line AA ′ shown in FIG. The gate electrode 435 also serves as one electrode of a storage capacitor of an adjacent pixel, and forms a capacitor in a portion overlapping with the semiconductor layer 453 connected to the pixel electrode 452. In addition, the source wiring 432
The relationship between the pixel electrode 450 and the adjacent pixel electrode 451 is such that the ends of the pixel electrodes 450 and 451 are connected to the source wiring 4.
By providing an overlapping portion on the light guide 32, stray light is blocked and light blocking properties are enhanced. FIG. 8 shows an equivalent circuit of such a pixel.

As described above, the driving circuit and the pixel portion of the active matrix display device shown in FIG. 3 described in the first embodiment can be formed.

[Embodiment 3] FIG. 16 shows an example in which an active matrix type display device is manufactured using an inverted stagger type TFT.
As in the second embodiment, a p-channel type TF
A peripheral circuit 1705 formed of a TFT T1701 and an n-channel TFT 1702; a pixel TFT 1703;
A pixel portion 1706 having 704 is formed. Although only a cross-sectional view of the p-channel TFT 1701 and the n-channel TFT 1702 of the peripheral circuit 1705 is shown, the gate signal line driving circuit described in Embodiment 1 using these TFTs,
A source signal line driver circuit, a video signal processing circuit, and a control circuit can be formed.

The substrate 1601 has a gate electrode 1602
1604, source or drain line 1606, 160
7. Capacitance wiring 1605 is molybdenum (Mo), tungsten (W), tantalum (Ta), aluminum (Al)
The first insulating film 16 formed of a material selected from the above and used as a gate insulating film with an insulating film containing silicon thereon.
08 is formed. The semiconductor films 1610 to 1613 are formed using a crystalline semiconductor material containing silicon, and have a region containing a p-type or n-type impurity. The channel protective films 1615 to 1616 are formed on the TFT channel formation region.
17 may be formed thereon, and a second insulating film 232 made of a silicon nitride or silicon nitride oxide film is formed thereover.
And a third insulating film 1633 made of an organic resin material. Then, aluminum (Al), titanium (T
i), source or drain wirings 1634-1637, a pixel electrode 1640, a gate wiring 1639, and a connection electrode 1638 are formed using tantalum (Ta) or the like.

P channel type TFT 1 of peripheral circuit 1705
In 701, a channel formation region 1707 and a source or drain region 1708 formed of a p-type impurity region are formed. An n-channel TFT 1702 includes a channel forming region 1709 and an LDD including an n-type impurity region.
A region 1710 and a source or drain region 1711 formed of an n-type impurity region are formed. Pixel section 170
The six pixel TFTs 1703 have a multi-gate structure,
A channel formation region 1712, an LDD region 1713, and source or drain regions 1714 to 1716 are formed. An n-type impurity region located between the LDD regions is useful for reducing off-state current. Retention capacity 1704
Are formed from a capacitor wiring 1605, a semiconductor layer 1613, and a first insulating layer formed therebetween.

In the pixel portion 1706, the connection electrode 16
38, the source wiring 1607 becomes a pixel TFT 1703
And the source or drain region 1714 is electrically connected. Further, the gate wiring 1639 is electrically connected to the first electrode. In addition, the pixel electrode 1640
Is the source or drain region 1 of the pixel TFT 1703
716 and the semiconductor layer 1613 of the storage capacitor 1704.

Even if such an inverted stagger type TFT is used,
Although a layer in which a gate electrode and a semiconductor film are formed is changed, a pixel having a structure similar to that of FIG. 7 can be formed.
Thus, the drive circuit and the pixel portion of the active matrix display device in FIG. 3 described in Embodiment 1 can be formed.

[Embodiment 4] An example in which an EL display device is manufactured using the active matrix display device having the structure shown in FIG. 3 will be described. Since the control circuit, the video signal processing circuit, the gate signal line driving circuit, and the source signal line driving circuit which detect ambient light intensity and correct the video signal have the same configuration, in this embodiment, the cross-sectional structure of the pixel portion is The outline is described with reference to FIG.

In FIG. 9A, 11 is a substrate, and 12 is a blocking layer. The substrate 11 is a translucent substrate, typically a glass substrate, a quartz substrate, a glass ceramic substrate,
Alternatively, a crystallized glass substrate can be used. However, it is necessary to withstand the highest processing temperature during the manufacturing process.

Reference numeral 701 denotes a switching TFT, and n
Although formed by a channel type TFT, the switching TFT may be a p-channel type. Reference numeral 702 denotes a current control TFT, and FIG.
The case where the FT 702 is formed of a p-channel TFT is shown. In this case, the drain of the current controlling TFT is connected to the anode of the EL element. However, the switching TFT is replaced by an n-channel TFT and a current control TFT.
Need not be limited to a p-channel TFT, and vice versa.
Or a p-channel TFT or an n-channel TFT
It is also possible to use FT.

The switching TFT 701 includes a source region 13, a drain region 14, LDD regions 15a to 15d,
High concentration impurity region 16 and channel forming regions 17a, 1
Active layer including 7b, gate insulating film 18, gate electrode 19
a, 19b, a first interlayer insulating film 20, a source line 21, and a drain line 22. Note that the gate insulating film 18 or the first interlayer insulating film 20 may be common to all TFTs on the substrate, or may be different depending on the circuit or element.

The switching T shown in FIG.
The FT 701 has a so-called double gate structure in which the gate electrodes 19a and 19b are electrically connected. Of course, not only a double gate structure but also a so-called multi-gate structure (a structure including an active layer having two or more channel forming regions connected in series) such as a triple gate structure may be used.

The multi-gate structure is extremely effective in reducing the off-state current. If the off-state current of the switching TFT 701 is sufficiently reduced, the capacitance required for the capacitor can be reduced accordingly. That is, since the area occupied by the capacitor can be reduced, the multi-gate structure is effective in increasing the effective light emitting area of the EL element 703.

Further, in the switching TFT 701, the LDD regions 15a to 15d
Are provided so as not to overlap with the gate electrodes 19a and 19b. Such a structure is very effective in reducing off-state current. The length (width) of the LDD regions 15a to 15d is 0.5 to 3.5 μm, typically 2.0 to 2.0 μm.
It may be 5 μm.

It is more preferable to provide an offset region (a region made of a semiconductor layer having the same composition as the channel forming region and to which no gate voltage is applied) between the channel forming region and the LDD region in order to reduce off-state current. Also,
In the case of a multi-gate structure having two or more gate electrodes, an isolation region 16 provided between channel formation regions
(A region where the same impurity element is added at the same concentration as the source region or the drain region) is effective in reducing off-state current.

Next, the current controlling TFT 702 includes the source region 26, the drain region 27, the channel forming region 29,
Gate insulating film 18, gate electrode 30, first interlayer insulating film 2
0, a source line 31 and a drain line 32. The gate electrode 30 has a single gate structure, but may have a multi-gate structure.

FIG. 9B is an equivalent circuit of a pixel of this EL display device. The drain of the switching TFT 701 is connected to the gate of the current controlling TFT 702.
Reference numeral 19 denotes a gate wiring constituting the gate electrodes 19a and 19b, and reference numeral 704 denotes a storage capacitor. Specifically, the gate electrode 30 of the current controlling TFT 702 in FIG. 9A is electrically connected to the drain region 14 of the switching TFT 701 via the drain wiring (also referred to as connection wiring) 22. The source wiring 31 is connected to the power supply line 705 in FIG.

From the viewpoint of increasing the amount of current flowing through the EL layer, the thickness of the active layer (particularly, the channel formation region) of the current controlling TFT 702 is increased (preferably 50 to 100 nm, more preferably 60 to 100 nm). -80 nm) is also effective. Conversely, in the case of the switching TFT 701, from the viewpoint of reducing the off current, the thickness of the active layer (particularly, the channel formation region) is reduced (preferably 20 to 50 nm, more preferably 25 to 40 nm).
It is also effective.

Reference numeral 47 denotes a first passivation film, which may have a thickness of 20 nm to 200 nm. As a material, an insulating film containing silicon (in particular, a silicon nitride oxide film or a silicon nitride film is preferable) can be used. This passivation film 47 has a role of protecting the formed TFT from alkali metals and moisture. The EL layer finally provided above the TFT contains an alkali metal such as sodium. That is, the first passivation film 47 also functions as a protective layer that prevents these alkali metals (mobile ions) from entering the TFT side.

Reference numeral 48 denotes a second interlayer insulating film, TF
It has a function as a flattening film for flattening a step formed by T. As the second interlayer insulating film 48, an organic resin film is preferable, and polyimide, polyamide, acrylic, B
It is preferable to use CB (benzocyclobutene) or the like. These organic resin films have an advantage that a good flat surface is easily formed and the relative dielectric constant is low. Since the EL layer is very sensitive to irregularities, it is desirable that the step due to the TFT is almost completely absorbed by the second interlayer insulating film. In order to reduce the parasitic capacitance formed between the gate wiring or data wiring and the cathode of the EL element, it is desirable to provide a thick material having a low relative dielectric constant. Therefore, the film thickness is preferably 0.5 to 5 μm (preferably 1.5 to 2.5 μm).

Reference numeral 49 denotes a pixel electrode (anode of an EL element) made of a transparent conductive film, and a contact hole (opening) is formed in the second interlayer insulating film 48 and the first passivation film 47.
After opening, the current control TF
It is formed to be connected to the drain wiring 32 of T702. If the pixel electrode 49 and the drain region 27 are not directly connected as shown in FIG. 9A, it is possible to prevent the alkali metal of the cathode from entering the active layer via the pixel electrode. .

A bump 59 is formed of an insulating material on the second interlayer insulating film 48, and an EL layer 51 is provided therebetween. Although the EL layer 51 is used in a single layer or a laminated structure, the luminous efficiency is better when used in a laminated structure. Generally, a hole injection layer / a hole transport layer / a light emitting layer / an electron transport layer are formed on a pixel electrode in the order of: a hole transport layer / a light emitting layer / an electron transport layer;
Or a hole injection layer / a hole transport layer / a light emitting layer / an electron transport layer /
A structure like an electron injection layer may be used. In the present invention, any known structure may be used, and the EL layer may be doped with a fluorescent dye or the like.

As the organic EL material, for example, the materials disclosed in the following US patents or publications can be used. U.S. Patent 4,356,429, U.S. Patent 4,539,507
No., U.S. Pat.No. 4,720,732, U.S. Pat.No. 4,769,292,
U.S. Pat.No.4,885,211; U.S. Pat.No. 4,950,950; U.S. Pat.
No. 061,617, U.S. Pat.No. 5,151,629, U.S. Pat.
No. 869, U.S. Pat.No. 5,294,870, JP-A-10-1895
No. 25, JP-A-8-241048, JP-A-8-241048
-78159.

Note that EL display devices are roughly classified into four color display methods, R (red), G (green), and B (blue).
A method of forming three kinds of EL elements corresponding to the above, a method of combining a white light emitting EL element and a color filter, and a combination of a blue or blue-green light emitting EL element and a phosphor (fluorescent color conversion layer: CCM) Method, cathode (counter electrode)
There is a method in which a transparent electrode is used to overlap EL elements corresponding to RGB. Note that EL includes light emission due to singlet excitation (fluorescence) and light emission due to triplet excitation (phosphorescence), and the EL referred to in this specification includes one including either one of them or light emission in which both are mixed. Point.

The structure shown in FIG. 9A is an example in which a method of forming three types of EL elements corresponding to RGB is used.
Although only one pixel is shown in FIG. 9A, pixels having the same structure are formed corresponding to the respective colors of red, green, and blue, whereby color display can be performed.

On the EL layer 51, a cathode 52 of an EL element is provided. As the cathode 52, a material containing magnesium (Mg), lithium (Li), or calcium (Ca) having a small work function is used. Preferably MgAg
(Material in which Mg and Ag are mixed at Mg: Ag = 10: 1)
May be used. In addition, MgAgAl electrode,
LiAl electrodes, and LiFAl and AlLi electrodes can be used.

After the EL layer 51 is formed, the cathode 52 is preferably formed continuously without opening to the atmosphere. Cathode 5
This is because the interface state between 2 and the EL layer 51 greatly affects the luminous efficiency of the EL element. Note that in this specification, a light-emitting element formed by a pixel electrode (anode), an EL layer, and a cathode is referred to as an EL element.

The laminate composed of the EL layer 51 and the cathode 52 is
Although it is necessary to individually form each pixel, the EL layer 51 is extremely weak against moisture, so that ordinary photolithography cannot be used. Therefore, it is preferable to selectively form the film by a vapor phase method such as a vacuum evaporation method, a sputtering method, and a plasma CVD method using a physical mask material such as a metal mask.

After the EL layer 51 is selectively formed using an ink jet method, a screen printing method, a spin coating method, or the like, a vapor deposition method, a sputtering method, and a plasma CVD method are used.
It is also possible to form the cathode by a gas phase method such as a method.

Reference numeral 53 denotes a protective electrode, which protects the cathode 52 from external moisture and the like, and at the same time, the cathode 52 of each pixel.
Is an electrode for connecting. As the protection electrode 53,
Aluminum (Al), copper (Cu) or silver (Ag)
It is preferable to use a low-resistance material containing The protective electrode 53 can also be expected to have a heat radiation effect of reducing heat generation of the EL layer 51. It is also effective to form the EL layer 51 and the cathode 52 continuously after forming the EL layer 51 and the cathode 52 up to the protective electrode 53 without exposing to the atmosphere.

A second passivation film 54 has a thickness of 10 nm to 1 μm (preferably 200 to 500 nm).
m). The purpose of providing the second passivation film 54 is mainly to protect the EL layer 51 from moisture, but it is also effective to have a heat radiation effect. However, as described above, since the EL layer is weak to heat, it is desirable to form the film at a temperature as low as possible (preferably in a temperature range from room temperature to 120 ° C.). Therefore, plasma CVD, sputtering,
A vacuum deposition method, an ion plating method or a solution coating method (spin coating method) can be said to be a desirable film forming method. In the structure shown in FIG. 9A, the light emission direction as viewed from the EL element is on the substrate 11 side, and the EL display device having such a pixel structure displays an image through the substrate 11.

On the other hand, FIG. 10A is a cross-sectional view of the pixel structure of the EL display device similar to FIG. 9A, and the light emission direction viewed from the EL element 703 is on the side opposite to the substrate 11. ,
The EL display device having such a pixel structure displays an image on the surface on which the EL element 703 is formed. In this case, the switching TFT 701 is similar to that shown in FIG.
As the current control TFT 706, an n-channel TFT is used. The current controlling TFT 706 includes a source region 66, a drain region 67, a channel forming region 69, and a gate insulating film 1.
8, gate electrode 60, first interlayer insulating film 20, source line 6
1 and a drain line 62. The gate electrode 60 has a single gate structure, but may have a multi-gate structure. FIG. 10B shows an equivalent circuit of such a pixel.

Reference numeral 53 denotes a pixel electrode (cathode side of the EL element) formed of Al, Cu, Ag or the like, on which the cathode 52 of the EL element is provided. It should be noted that the interface state between the cathode 52 and the EL layer 51 greatly affects the luminous efficiency of the EL element. The EL layer 51 is similarly formed with a single layer or a stacked structure. A transparent electrode (anode side) 49 is provided thereon, and a second passivation film 54 is further provided.

The gist of the present invention is that, in an active matrix EL display device, a change in environment is detected by a sensor, the amount of current flowing through the EL element is controlled based on this information, and the luminance of the EL element is controlled. It is.
Therefore, the present invention is not limited to the structure of the EL display device in FIG. 9A, and the structure in FIG. 9A is a preferred embodiment in the active matrix display device having the structure shown in FIG. Just one. In this way,
The pixel portion of the active matrix display device described in Embodiment 1 can be manufactured using an EL element.

[Embodiment 5] FIG. 12 is a conceptual diagram of mounting the optical sensor shown in Embodiment 1 on an active matrix type display device. Although this embodiment shows a liquid crystal display device as an example, the concept of mounting an optical sensor manufactured on a separate substrate on an active matrix substrate can be applied to an EL display device as it is.

On the first substrate 800 on which the pixel portion is formed, a driving circuit (A) 801, a driving circuit (B) 802, a pixel portion 803, an external input / output terminal 804, and a connection wiring 805 are formed. The pixel portion 803 is formed by arranging pixel TFTs in a matrix as shown in the second embodiment. The driving circuit (A) 801 and the driving circuit (B) 802 are manufactured in a similar manner. A counter electrode 809 is formed on the second substrate 808 and is bonded to the first substrate 800 with a sealant 810. Liquid crystal is sealed inside the sealing material 810 and the liquid crystal layer 8 is formed.
11 is formed. The first substrate and the second substrate are attached at a predetermined interval, and the thickness is 3 to 8 μm for a nematic liquid crystal and 1 to 4 μm for a smectic liquid crystal.

An FPC (Flexible Printed Circuit) 812 for inputting power and control signals from outside is attached to the external input / output terminal 804. A reinforcing plate 813 may be provided to increase the bonding strength of the FPC 812.

A thin-film element whose photoelectric conversion layer is made of amorphous silicon or CdS is used. The optical sensor 806 is the third
A plurality of substrates manufactured on the substrate 807 are divided and mounted on the first substrate 800. The mounting method is slightly different depending on the light incident direction of the optical sensor and the display direction of the pixel portion, but is basically mounted by a face-down method using a conductive resin.

FIG. 11 shows an example of an optical sensor using amorphous silicon for the photoelectric conversion layer. FIG. 11A illustrates a structure in which a transparent electrode 602, a photoelectric conversion layer 603,
The optical sensor in which the light reflective electrodes 604a and 604b are formed is shown. The photoelectric conversion layer 603 has a pin junction formed, and the I-type layer is formed of amorphous silicon. The direction of bonding is arbitrary. For example, the p-type layer contacts the transparent electrode 602 and the n-type layer
4a and 604b. Transparent electrode 6
Reference numeral 02 denotes openings 605 and 606 which are separated from the end of the substrate 601 to prevent a short circuit. The external connection terminal also serves as a light-reflective electrode, and the light-reflective electrode 604a is electrically connected to the transparent electrode through an opening 607 formed in the photoelectric conversion layer 603, and becomes a positive terminal. The light reflective electrode 604b forms a negative terminal.
In the case of FIG. 11A, the light-receiving surface is on the light-transmitting substrate 610 side, and light transmitted through the substrate 601 is incident on the photoelectric conversion layer.

FIG. 11B shows an optical sensor in which a light reflective electrode 611, a photoelectric conversion layer 612, and a transparent electrode 613 are formed on a substrate 610. The photoelectric conversion layer 612 has p
The in-junction is formed, and the I-type layer is formed of amorphous silicon. The direction of joining is arbitrary,
A structure in which the p-type layer contacts the transparent electrode 613 and the n-type layer contacts the light-reflective electrode 611 is preferable. Light reflective electrode 61
1. The photoelectric conversion layer 612 is formed in the substrate 61 through the openings 614 and 615.
0 to prevent short circuit. External connection terminal 6
17 and 618 are made of a conductive paste such as silver, and are selectively formed on the transparent electrode. The external connection terminal 617 is electrically connected to the light-reflective electrode through the opening 614 and becomes a negative terminal (contact on the n-layer side). The connection terminal 618 forms a + terminal (a contact on the p-layer side). In the case of FIG. 11B, the light receiving surface is the side where the transparent electrode 613 is formed.

As described above, the optical sensors can be classified into two types when viewed from the surface where light enters the photoelectric conversion layer.
The optical sensor is mounted on a substrate provided with a pixel portion, a driver circuit, and a control circuit. In that case, the optical sensor is mounted so as to form a wiring and a contact formed on the same surface of the substrate. FIG. 13 shows the details of that part.

FIG. 13A shows an example in which the optical sensor of FIG. 11A is mounted. In this case, light enters the optical sensor from the side of the substrate 601 where the optical sensor is formed. The optical sensor is mounted in accordance with the wiring 850 formed on the substrate 800, and is bonded with a light or thermosetting resin 852. A contact with the wiring 850 is formed by conductive particles 851 contained in the resin 852.

FIG. 13B shows an example in which the optical sensor of FIG. 11B is mounted. In this case, the substrate 80
The light transmitted through 0 is incident on the optical sensor. The optical sensor is a wiring 850 formed on the substrate 800.
And adhered with a conductive material 853 such as cream solder or silver paste.

As shown in FIG. 12, a plurality of photosensors are formed on a third substrate 807 and mounted on a first substrate 800 on which a pixel portion and a driving circuit are formed to complete a display device. Can be simplified. The design rules of the optical sensor used in the present invention and the substrate forming the active matrix display device are different, and the latter requires a design rule of several μm to sub-micron, while the former requires several tens to several hundreds of microns. Manufactured according to design rules. The optical sensor can form a pattern by laser processing, screen printing, or the like.

[Embodiment 6] FIG. 14 shows an example of a method of incorporating an active matrix type display device on which an optical sensor as shown in Embodiment 1 is mounted in various electronic devices. FIG.
4A is an example of such a case, in which a substrate 901 on which elements such as TFTs are formed and a counter substrate 902 are provided, and an element formation region 903 is provided therebetween. Although the detailed structure of the element formation region 903 is omitted, in the case of a liquid crystal display device, FIG.
A liquid crystal layer and the like are formed over a pixel electrode in addition to the pixel TFT shown in FIG. In the case of an EL display device, a switching TFT, a current control TFT, an EL element, and the like illustrated in FIG. 9A or FIG. 10A are formed. In addition, various circuits provided around the pixel portion as shown in FIG. 3 may be included. The element formation region 903 is sealed between the two substrates with a sealant 904 so as not to be exposed to the outside air, thereby improving the reliability of the display device.

[0111] The optical sensor 907 is fixed to the substrate 901 on which the pixel portion is formed, and forms an electrical connection with a circuit in the element formation region 903. The connection method in this case is shown in FIG.
The method (A) is employed. It is mounted outside the counter substrate 902. One end of the input / output terminal 908 is a flexible printed circuit (FP).
C) 909, and is connected to a printed circuit board 910 provided with a signal processing circuit, an amplifier circuit, a power supply circuit, and the like, so as to transmit signals necessary for image display. Also,
Although the polarizing plate is omitted, it may be provided as needed as needed.

Image display (display light) is performed by light emitted to the counter substrate 902 side, and this surface becomes the surface. Light enters the optical sensor through an opening 91 provided in the housing 915.
Light enters from 6. in this case. Fig.11 Optical sensor
The one having the structure shown in FIG. The output from the optical sensor is connected to a control circuit via a wiring 906.

The structure shown in FIG. 14A can be applied to a reflection type liquid crystal display device. Although not shown, a backlight can be provided below the substrate 901 on which the pixel portion is formed, so that the device can be used for a transmission-type liquid crystal display device. In addition, the present invention can be applied to an EL display device having a structure as shown in FIG.

FIG. 14B shows another example, in which a substrate 920 on which an element such as a TFT is formed and a counter substrate 921 are fixed with a sealant 923, and an element formation region 922 is provided therebetween.
Is provided. The optical sensor 925 is fixed to a substrate 920 on which an element such as a TFT is formed, and is electrically connected to a circuit in an element formation region. This connection method is shown in FIG.
The method (B) is adopted. One end of the input / output terminal 926 is connected to a flexible printed circuit board (Flexible Printed C).
ircuit (FPC) 927 and a printed circuit board 928 provided with a signal processing circuit, an amplifier circuit, a power supply circuit, and the like, so as to transmit a signal necessary for image display. The image display (display light) is emitted to the substrate 920 side,
This surface becomes the surface. External light is introduced through an opening 930 provided in the housing 929, and light transmitted through the substrate 920 provided with an element such as a TFT enters the optical sensor 925. The output from the optical sensor is connected to a control circuit by a wiring 924.

The structure shown in FIG. 14B can be applied to an EL display device having a structure in which light of an EL layer is emitted to the substrate side as shown in FIG. 9A.

The method of mounting the display device shown here is an example, and can be appropriately assembled according to the form of the display device.

[Embodiment 7] FIG. 17 shows an example in which an optical sensor is formed integrally with a substrate on which elements such as TFTs are formed.
The p-channel TFT 852 and the n-channel TFT 853 of the peripheral circuit 851 are manufactured in the same manner as in the second embodiment.
A blocking layer 857 is formed over a substrate 856, and semiconductor films 858 and 859, gate insulating films 860 and 861, and gate electrodes 862 and 863 are formed. The gate insulating films 860 and 861 are etched so that the surfaces of the semiconductor films 858 and 859 are exposed outside the gate electrodes 862 and 863. On the gate electrodes 862 and 863, a passivation film 864 and an interlayer insulating film 865 made of an organic resin material are formed, and source or drain electrodes 866 to 869 are formed.

Semiconductor film 85 of p-channel TFT 852
8 and the channel formation region and the n-type impurity region formed in the semiconductor film 859 of the n-channel TFT 853 are described in detail in FIG. ) P-channel TFT
453 and an n-channel TFT 454.

On the other hand, the optical sensor 854 is a TFT
It is manufactured in the same process as the above. The p-type semiconductor region 870 and the n-type semiconductor region 871 are formed of the same crystalline semiconductor as the semiconductor films 858 and 859. The p-type or n-type impurity element is formed at the same time when the impurity region of the TFT is formed. And so as to overlap this impurity semiconductor,
An amorphous silicon film 872 is formed with a thickness of 500 to 1000 nm. This amorphous silicon film 872 is desirably an intrinsic semiconductor, whereby a pin junction is formed. 873 is an electrode for making contact with the p-type semiconductor region 870, and 874 is an electrode for making contact with the n-type semiconductor region.

Light is incident on the optical sensor 854 by the substrate 85.
6 can be performed, and can also be performed from the side where the amorphous silicon film 872 is formed. Therefore, the method for assembling into the housing shown in the sixth embodiment is the same as that shown in FIG.
4 Any of the methods (A) and (B) can be adopted.

In this embodiment, the TFT is shown with the top gate type structure described in Embodiment 2, but the photosensor of this embodiment can be combined with the inverted staggered TFT shown in Embodiment 3. The display device provided with such an optical sensor can be applied to both a liquid crystal display device and an EL display device.

[Embodiment 8] The active matrix display device of the present invention can be used for various electronic devices. Such electronic devices include video cameras, digital cameras, projectors (rear or front type), head mounted displays (goggle type displays),
Examples include a car navigation, a car stereo, a personal computer, and a portable information terminal device (a mobile computer, a mobile phone, an electronic book, or the like). Examples of these are shown in FIGS.

FIG. 18A shows a personal computer, which is composed of a main body 9001, an image input section 9002, and a display device 9.
003, a keyboard 9004, and the like. The present invention can be used for the display device 9003, and the luminance of the display device 9003 can be controlled by an optical sensor provided in the light receiving portion 9005 according to ambient brightness.

FIG. 18B shows a video camera, which includes a main body 9101, a display device 9102, an audio input portion 9104, operation switches 9103, a battery 9106, and an image receiving portion 91.
05 and the like. The invention can be used for the display device 9102, and the luminance of the display device 9102 can be controlled by an optical sensor provided in the light receiving portion 9107 in accordance with ambient brightness.

FIG. 18C shows a mobile computer or a PDA (Personal Digital Assistant: personal information terminal).
And so on. The present invention can be used for the display device 9205, and the luminance of the display device 9205 can be controlled by an optical sensor provided in the light receiving portion 9206 in accordance with ambient brightness.

FIG. 18D shows a goggle type display, which includes a main body 9301, a display device 9302, and an arm 93.
It consists of 03 mag. The invention can be used for the display device 9302, and the luminance of the display device 9302 can be controlled by an optical sensor provided in the light receiving portion 9304 in accordance with ambient brightness.

FIG. 18E shows a player that uses a recording medium (hereinafter, referred to as a recording medium) on which a program is recorded, and includes a main body 9401, a display device 9402, and a speaker 94.
03, a recording medium 9404, an operation switch 1223, and the like. This player uses a DVD (Di
Gital Versatile Disc), CDs, etc., can be used for music appreciation, movie appreciation, games, and the Internet.
The present invention can be used for the display device 9402, and the luminance of the display device 9402 can be controlled by an optical sensor provided in the light receiving portion 9406 in accordance with ambient brightness.

FIG. 18F shows a digital camera, which includes a main body 9501, a display device 9502, an eyepiece 9503, operation switches 9504, an image receiving unit (not shown), and the like. The present invention can be used for the display device 9502,
The luminance of the display device 9502 can be controlled by an optical sensor provided in the 9505 in accordance with ambient brightness.

FIG. 19A shows a mobile phone, which includes a display panel 1401, an operation panel 1402, a connection portion 1403,
Display device 1404, audio output unit 1405, operation keys 14
06, a power switch 1407, an audio input unit 1408, an antenna 1409, and the like. The present invention can be used for the display device 1404, and the luminance of the display device 1404 can be controlled by an optical sensor provided in the light receiving portion 1410 according to ambient brightness.

FIG. 19B shows a portable book (electronic book), which includes a main body 1411, a display device 1412, and a storage medium 141.
3, including an operation switch 1414, an antenna 1415, and the like. The present invention can be used for the display device 1412, and the luminance of the display device 1412 can be controlled by an optical sensor provided in the light receiving portion 1416 according to ambient brightness.

FIG. 19C shows a television receiver, which includes a main body 1416, a support base 1417, a display device 1418, and the like. The present invention can be used for the display device 1418, and the luminance of the display device 1418 can be controlled by an optical sensor provided in the light receiving portion 1420 according to ambient brightness. The television receiver of the present invention is particularly advantageous when the screen is enlarged, and is advantageous for a display having a diagonal of 10 inches or more (especially 30 inches or more).

As described above, the applicable range of the present invention is extremely wide, and can be applied to electronic devices in various fields.

[0133]

According to the display device of the present invention, it is possible to adjust the light emission luminance of the display device by detecting the ambient brightness by using an optical sensor. By adjusting the brightness of the image displayed on the pixel portion of the display device, the brightness is increased when the surroundings are bright, and the brightness is decreased when the surroundings are dark, so that a video display that is easy for the user to see is provided. It is also possible to reduce the power consumption of an electronic device equipped with the device.

[Brief description of the drawings]

FIG. 1 illustrates a structure of a digitally driven display device of the present invention.

FIG. 2 is a circuit diagram of a source follower for reading an output of an optical sensor.

FIG. 3 illustrates a layout of an optical sensor, a pixel portion, a driver circuit, and a control circuit.

FIG. 4 is a cross-sectional view illustrating a manufacturing process of a TFT in a pixel portion and a peripheral circuit.

FIG. 5 is a cross-sectional view illustrating a manufacturing process of a TFT in a pixel portion and a peripheral circuit.

FIG. 6 is a cross-sectional view illustrating a manufacturing process of a TFT in a pixel portion and a peripheral circuit.

FIG. 7 is a top view illustrating a pixel structure of a pixel portion.

FIG. 8 is a circuit diagram of a pixel in a liquid crystal display device.

FIG. 9 is a cross-sectional view and an equivalent circuit of a pixel in an EL display device.

FIG. 10 is a cross-sectional view and an equivalent circuit of a pixel in an EL display device.

FIG. 11 is a cross-sectional view of an optical sensor.

FIG. 12 is an assembly view of a display device on which an optical sensor is mounted.

FIG. 13 is a cross-sectional view illustrating a connection method of an optical sensor and an incident direction of light.

FIG. 14 is a cross-sectional view illustrating a state where the display device of the present invention is incorporated in a housing.

FIG. 15 illustrates a configuration of an analog-driven display device of the present invention.

FIG. 16 is a cross-sectional view illustrating a TFT in a pixel portion and a peripheral circuit.

FIG. 17 is a cross-sectional view of an optical sensor integrally formed on a substrate.

FIG. 18 illustrates an example of an electronic device in which the display device of the present invention is incorporated.

FIG. 19 illustrates an example of an electronic device in which the display device of the present invention is incorporated.

FIG. 20 is a diagram showing the operation of the time division gray scale method.

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Claims (13)

[Claims] An output line of a gamma correction circuit is connected to a video signal processing circuit, and a plurality of optical sensors for changing an output voltage of the gamma correction circuit in accordance with ambient brightness are provided. Display device. 2. An output line of a gamma correction circuit is connected to a video signal processing circuit, and a plurality of optical sensors for changing an output voltage of the gamma correction circuit according to ambient brightness are formed on a second substrate. The display device, wherein the second substrate is fixed to the first substrate. 3. A semiconductor device comprising: a plurality of light sensors for detecting ambient brightness; and a gamma correction circuit for outputting a voltage for determining a period during which a pixel is in a bright state based on an electric signal of the light sensor. Display device. 4. A plurality of optical sensors provided on an outer peripheral portion of a substrate on which a pixel portion is formed, a source follower circuit connected to the plurality of optical sensors, a gamma correction circuit connected to the source follower circuit, A display device comprising: a video signal amplifier circuit connected to the gamma correction circuit; a source signal line driver circuit connected to the video signal amplifier circuit; and a pixel unit connected to the source signal line driver circuit. 5. A source follower circuit, wherein a plurality of optical sensors formed on a second substrate are fixed to an outer peripheral portion of a first substrate on which a pixel portion is formed, and a source follower circuit connected to the plurality of optical sensors. A gamma correction circuit connected to a source follower circuit, a video signal amplification circuit connected to the gamma correction circuit, a source signal line driving circuit connected to the video signal amplification circuit, and a pixel unit connected to the source signal line driving circuit A display device comprising: 6. The display device according to claim 4, wherein the pixel portion has at least a pixel electrode, a liquid crystal layer, and a counter electrode. 7. The display device according to claim 4, wherein the pixel portion has at least a pixel electrode and a light emitting layer. 8. The display device according to claim 1, wherein the optical sensor includes an amorphous silicon layer in a photoelectric conversion layer. 9. A step of forming a pixel portion with a thin film transistor on a first substrate, a step of forming an optical sensor on a second substrate, and a step of fixing the second substrate to the first substrate And a method for manufacturing a display device. 10. A step of forming a pixel portion with a thin film transistor on a first substrate, a driving circuit of the pixel portion, and a control circuit for controlling luminance of the pixel portion, and an optical sensor on a second substrate. Forming the second substrate and the second substrate on the first substrate.
Fixing the substrate, and electrically connecting the control circuit to the optical sensor. 11. The method for manufacturing a display device according to claim 9, wherein the pixel portion includes at least a pixel electrode, a liquid crystal layer, and a counter electrode. 12. The method for manufacturing a display device according to claim 9, wherein the pixel portion includes at least a pixel electrode and a light emitting layer. 13. The method for manufacturing a display device according to claim 9, wherein the optical sensor includes an amorphous silicon layer formed on a photoelectric conversion layer.