KR101675841B1 - Photo Sensor of Display Device and Method of Manufacturing the Same - Google Patents

Abstract

The present invention relates to a photosensor of a display device capable of adjusting the brightness of a light emitting unit in a display device according to illuminance by receiving external light, and a method of manufacturing the same. In the photosensor of the display device of the present invention, A substrate having a light receiving region in which a thin film transistor array is formed on the display region and in which a part of the non-display region receives external light; and a substrate formed on the light receiving region and having the same first type impurity A semiconductor layer formed of polysilicon doped and defined as a source region and a drain region and having an intrinsic area between the source region and the drain region; and a gate electrode formed on the intrinsic region adjacent to the drain region of the semiconductor layer A control electrode, and a source electrode and a drain, which are in contact with the source and drain regions of the semiconductor layer, That made, including polar characterized.

Photo sensor, liquid crystal display, photodiode

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a photo sensor and a method of manufacturing the same,

The present invention relates to a display device, and more particularly, to a photosensor of a display device and a method of manufacturing the same, capable of adjusting the luminance of a light emitting unit in a display device by receiving external light and adjusting the luminance according to the illuminance.

As the information age has come to a full-fledged information age, the display field for visually expressing electrical information signals has been rapidly developed. In response to this, various flat display devices having excellent performance such as thinning, lightweighting and low power consumption have been developed. Devices have been developed and are rapidly replacing existing cathode ray tubes (CRTs).

Specific examples of such a flat panel display include a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED) (Electro Luminescence Display Device: ELD). In general, a flat panel display panel that realizes an image is an essential component. The flat panel display panel has a pair of light emitting or polarizing material layers interposed therebetween And a transparent insulating substrate facing each other.

In a liquid crystal display device, an image is displayed by adjusting the light transmittance of a liquid crystal using an electric field. To this end, the image display apparatus includes a display panel having a liquid crystal cell, a backlight unit for irradiating the display panel with light, and a drive circuit for driving the liquid crystal cell.

In the field of such a liquid crystal display device, an active matrix liquid crystal display (hereinafter referred to as " AMLCD ") is the mainstream. In this AMLCD, a thin film transistor (TFT) defines one pixel, One TFT controls the voltage level of the pixel by the switching element to change the light transmittance of the pixel to display the image.

A general liquid crystal display device includes a liquid crystal panel having a plurality of TFTs arranged in a matrix form to display an image, a gate driver for controlling the input of data signals to the liquid crystal panel, a data driver for outputting data signals to the liquid crystal panel A timing controller for controlling timings of the respective drivers, and a backlight unit for irradiating light to the liquid crystal panel, the backlight unit being formed on the back surface of the liquid crystal panel and configured to perform a visual display of a data signal, And a backlight control unit for controlling the backlight unit. In addition, each of the above-described configurations is supplied with driving power by a power supply unit that supplies appropriate power required for driving, and each of the controls is usually integrated on a printed circuit board (PCB).

Also, although not shown, the backlight unit may be one or more fluorescent lamps or a plurality of LEDs (light emitting diodes).

In a liquid crystal display device having such a structure, a hydrogenated amorphous silicon (a-Si: H, hereinafter referred to as amorphous silicon) is mainly used as the semiconductor layer of the TFT. Deposition can be performed at a low substrate temperature and an inexpensive insulating substrate can be used.

However, the above-described amorphous silicon has a problem in that its properties are deteriorated by light irradiation, and it is difficult to use in a driving circuit due to the electric characteristics (low electric field effect mobility: 0.1 to 1.0 cm 2 / V · s) .

Therefore, the amorphous silicon thin film transistor substrate uses a TCP (Tape Carrier Package) driving integrated circuit (IC) to connect the insulating substrate and the printed circuit board (PCB), which causes the driving IC and the mounting cost to take a large portion do.

Meanwhile, the liquid crystal panel is divided into a display region in which two substrates are adhered, a thin film transistor is formed and displays an image, and a non-display region in which a driver and a signal wiring are formed.

In more detail, a plurality of gate lines and data lines are formed in a matrix in the display region, and TFTs (thin film transistors) are provided at intersections of the gate lines and the data lines.

The gate driver and the data driver receive a scan signal and a data signal from the outside and control the TFT of the display region through the gate line and the data line to change the light transmittance of the liquid crystal.

Although not shown, the timing controller and the power supply unit are separately mounted on the PCB substrate, connected to the gate driver and the data driver, and the backlight unit is also provided on the back surface of the liquid crystal panel.

In the above-described liquid crystal display using amorphous silicon or polysilicon, since the light generated in the backlight unit is constant, it is difficult to control the brightness and brightness of the liquid crystal display device in accordance with the external brightness and brightness. Therefore, there is an attempt to control the input voltage of the backlight unit to control the brightness and brightness of such a liquid crystal display device. The external brightness and brightness are measured using a photosensor or the like, and fed back to measure the brightness and brightness of the backlight lamp of the liquid crystal display. It has been attempted to control luminance and luminance.

Hereinafter, a conventional photo sensor will be described with reference to the accompanying drawings.

1 is a cross-sectional view showing a conventional photo sensor.

1, a conventional photosensor includes a substrate 10 having a semiconductor substrate as a wafer in the form of a diode, a light-shielding layer 11 on the substrate 10, a light- A buffer layer 12 on the semiconductor layer 13 and a semiconductor layer 13 in which regions are sequentially defined on the side by p + type 13a, intrinsic region 13b and n + And a source electrode 15a and a drain electrode 15b formed on the n + -type layer 13a and the n + -type layer 13c, respectively, with interlayer insulating film 14 interposed therebetween.

Here, a protective film 16 is further formed on the device for protecting the source electrode 15a and the drain electrode 15b.

In this case, for example, when a reverse bias is applied to the photo sensor, that is, a voltage of 0 V is applied to the source electrode 15a and a positive positive voltage is applied to the drain electrode 15b (Vds A positive voltage is applied), and the photocurrent with respect to Vds linearly increases with application of external light.

Accordingly, the degree of external light can be sensed according to the photocurrent value measured from the photosensor.

However, the conventional photo sensor is formed in a liquid crystal display device separately from the liquid crystal panel and is formed on a semiconductor wafer, which requires a separate module for voltage application and measurement, which causes a rise in price.

Further, the semiconductor layer included in the photosensor is defined as a p + type-intrinsic region-n + type, and a doping mask for defining the p + type and the n + type is individually required, which places a heavy burden on the mask process required for the process .

The conventional photosensor of the liquid crystal display has the following problems.

It is possible to operate the liquid crystal display panel separately from the liquid crystal panel through a module provided separately and to mount the liquid crystal panel on a device other than the liquid crystal panel and a process for forming such a module, This is big.

In addition, as a device, a mask for p-type and n-type is individually required in order to define at least the region of the semiconductor layer in the form of PIN diodes, which increases the number of mask processes.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a photo sensor and a photo sensor of a display device which can change the structure and manufacturing method of a photo sensor, And a method for producing the same.

According to an aspect of the present invention, there is provided a photo sensor including a display region and a non-display region, a thin film transistor array formed on the display region, and external light being received in a part of the non- A semiconductor device comprising: a substrate having a light receiving region; a substrate formed on the light receiving region and doped with the same first type impurity on both sides to define a source region and a drain region, and having an intrinsic area between the source region and the drain region A control electrode formed on the intrinsic region adjacent to the drain region of the semiconductor layer and a source electrode and a drain electrode contacted with the source region and the drain region of the semiconductor layer, .

Here, the first type impurity is a p + type impurity.

A first insulating layer between the semiconductor layer and the control electrode; And a second interlayer insulating film may be further formed between the control electrode and the source electrode / drain electrode.

A contact hole may be further formed in the second interlayer insulating film and the first interlayer insulating film on the semiconductor layer connected to the source electrode and the drain electrode. In this case, an open region may be further formed in the second interlayer insulating film on the semiconductor layer on which the control electrode is not formed.

In addition, a shielding layer may be further formed on the substrate corresponding to the lower portion of the semiconductor layer.

In this case, it is preferable that the control electrode is formed to have a length equal to or less than 1/4 of the length of the intrinsic region of the semiconductor layer.

(Vds -2) V? Vds? (Vds + 3) V with respect to the drain electrode-source electrode voltage (Vds) is preferably applied to the control electrode, A positive positive voltage is applied to the gate electrode.

A method of manufacturing a photosensor of a display device for achieving the same object includes the steps of preparing a substrate having a light receiving area in which a part of the non-display area is divided into a display area and a non- Forming a first insulating film on the substrate including the semiconductor layer; forming an electrode pattern covering a portion on the semiconductor layer; Forming a source region and a drain region by doping a semiconductor layer on both sides of the electrode pattern with a first-type impurity; forming a second insulating film on the first insulating film including the semiconductor layer and the electrode pattern, And selectively removing the second insulating film and the first insulating film to expose a part of the source region and the drain region Forming an open region for selectively removing the second insulating film and opening an outer region of the electrode pattern so as to leave only a region adjacent to the drain region; Forming a metal layer on the second insulating film and selectively removing the metal layer to form a source electrode and a drain electrode connected to the source region and the drain region in the contact hole.

At this time, in the step of forming the source electrode and the drain electrode by selectively removing the metal layer, the electrode pattern under the open region is removed together to form the control electrode.

The first-type impurity may be p + -type or n + -type.

In this case, it is preferable that the contact hole and the open region are formed by one mask.

Here, a shielding layer may be further formed under the semiconductor layer.

The display region includes a gate line and a data line intersecting with each other, and a thin film transistor including a pixel portion semiconductor layer formed of polysilicon formed at an intersection of the gate line and the data line, The control electrode is formed on the same layer as the gate line, and the source / drain electrode is formed on the same layer as the data line.

The above-described photosensor of the display device of the present invention and its manufacturing method have the following effects.

In the photosensor of the display device of the present invention, the doping region of the semiconductor layer is a p + -type or n + -type and only one conductivity type impurity is used. The impurity layer can be defined by only one conductivity type, and the mask process is reduced.

Further, the photosensor can be formed together with the step of forming the thin film transistor array of the display device, which is remarkably effective in reducing the cost of the device as compared with the case of covering the photosensor.

In addition, the current-voltage characteristic is changed according to the voltage condition applied to the control electrode, and the optical sensing can be performed using the same, which is advantageous for application as a device and can be used in various applications for sensing light, You can use it. .

In addition, when the length of the semiconductor layer is increased for the convenience of photocurrent measurement and an amplifier or the like is provided, the photocurrent sensing is possible in a wide section of Vds, and the reading of the luminance can be easily performed.

Hereinafter, a photosensor and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a cross-sectional view showing a photosensor of the display device of the present invention.

2, the photosensor of the display device of the present invention includes a buffer layer 101, a p + type region 102a, an intrinsic area 102b, a p + type region 102c And a second insulating film 103 formed on the semiconductor layer 102. The first insulating film 103 is formed on the semiconductor layer 102. The first insulating film 103 is formed on the semiconductor layer 102, a control electrode 104 and a source electrode 106 and a drain electrode 107 which are connected to the source region 102a and the drain region 102c via a second insulating film 105, .

Here, since the semiconductor layer 102 is a polysilicon layer crystallized at a low temperature and has an electric mobility equal to or more than a certain level, the semiconductor layer 102 can be used for the device configuration in a circuit.

Here, the substrate 100 of the display device is divided into a display region and a non-display region, a thin film transistor array is formed on the display region, and a light receiving region where a part of the non-display region receives external light , The photosensor of Fig. 2 shown in Fig. 2 is located corresponding to a part of a non-display area where external light is received.

In this case, a thin film transistor array is formed in a display region of the substrate 100 (not shown), and a photosensor of the display device of the present invention is formed in the same process as the thin film transistor array.

The photosensor is preferably a region that receives light of external light among the non-display regions of the substrate 100, and does not contribute to the display but is not covered by the casing water.

On the other hand, a display device using the photosensor of the present invention may be, for example, a liquid crystal display device which can use a backlight unit as a light emitting unit. In addition, as an organic light emitting display device or an electrophoretic display device, It is possible to apply the present invention to a control unit which can adjust current or voltage applied to each cell to a different level so as to control the degree of light emission according to external light sensed by the photosensor.

Here, the p + -type impurity is shown for defining the source region 102a and the drain region 102c of the semiconductor layer 102, but this is taken into consideration when the thin film transistor formed in the display device is a p-type transistor If the thin film transistor formed in the display device is an n-type transistor, n + -type impurities may be doped. In any case, impurities doped into the source region 102a and the drain region 102c are defined as one mask together in the same process with the same impurity.

On the other hand, a contact hole is formed in the second interlayer insulating film 105 and the first interlayer insulating film 103 on the semiconductor layer 102 connected to the source electrode 106 and the drain electrode 107, A metal layer for forming the source electrode and the drain electrode is buried. In addition, an open region may be further formed in the second interlayer insulating film 105 on the semiconductor layer on which the control electrode 104 is not formed. In this case, when the gate line and the gate electrode of the thin film transistor array of the display region are formed, the control electrode 104 is formed with an electrode pattern corresponding to the intrinsic region 102b, The second interlayer insulating film 105 is etched to expose only a portion of the electrode pattern not close to the drain region in the process of forming the open region. Thereafter, in the etching process for forming the data lines of the thin film transistor array, the control electrode 104 is formed by patterning the source electrode 106 and the drain electrode 107 together and removing the exposed electrode pattern together will be.

In this case, the control electrode 104 is formed of the same metal as the gate line, and the definition of the pattern is defined when the source electrode 106 and the drain electrode 107 are formed.

A shielding layer may be further formed on the substrate 100 corresponding to the lower portion of the semiconductor layer 102 to prevent an error caused by the backlight unit coming from the lower portion.

However, the light-receiving region in which the photosensor is located may be a non-display region, and the light-emitting region of the backlight unit may not overlap the photosensor forming region, so that the shielding layer may be omitted.

3 is a plan view of the semiconductor layer of FIG.

As shown in FIG. 3, the source region 102a, the intrinsic region 102b, and the drain region 102c are sequentially defined on a side-by-side basis when the regions of the semiconductor layer 102 are viewed from left to right. In this case, 102b are polysilicon regions that are not doped with impurities and the remaining source and drain regions 102a and 102c are regions doped with p + type impurities.

The control electrode 104 is arranged so as to overlap with the intrinsic region 102b adjacent to the drain region 102c with respect to the semiconductor layer 102. [

At this time, the width (W) corresponding to the vertical length of the semiconductor layer 102 in the drawing and the horizontal length of the intrinsic region not overlapping with the control electrode (104) are defined as the length (L) The lateral length Lg of the control electrode overlapping with the intrinsic region is compared with the length L of the semiconductor layer.

Experiments were carried out with a width Lg of the control electrode overlapping with the intrinsic region of about 2 m. The width Lg of the control electrode overlapped with the intrinsic region was determined by the length of the intrinsic region of the semiconductor layer L) of about 1/4 or less.

On the other hand, the photosensor of the display device having the above-described control electrode can change the quasi Fermi level of the semiconductor layer 102 made of polysilicon by the asymmetry of its structure. That is, if the control electrode 104 is considered similar to the gate electrode, it operates similarly to a p-type thin film transistor having a long offset at one side.

In this case, the photosensor of the present invention exhibits a current-voltage characteristic in which the photocurrent changes according to the voltage applied to the control electrode 104. By controlling the voltage applied to the control electrode 104 Photocurrent measurement is possible.

The method of manufacturing the photosensor of the display device of the present invention will be described with reference to FIGS. 2 and 3. FIG.

A substrate (100) having a light receiving area divided into a display area and a non-display area and receiving a part of the non-display area is prepared.

Next, a buffer layer 101 is formed to prevent damage to the substrate 100 before crystallization.

Then, the semiconductor layer 102 is formed on the light receiving region by low-temperature crystallization. In this case, a thin film transistor forming semiconductor layer is also formed in the display region.

Next, a first insulating layer 103 is formed on the substrate 100 including the semiconductor layer 102.

Next, an electrode pattern (not shown) for covering a part of the semiconductor layer 103 is formed and doped with a first type impurity to the semiconductor layers on both sides of the electrode pattern using the electrode pattern (not shown) as a mask Thereby forming a source region 102a and a drain region 102c. At this time, the region where the impurity is not doped between the source region 102a and the drain region 102c is the intrinsic region 102b. In addition, an electrode pattern is formed in a size corresponding to the intrinsic region 102b. At this time, a gate electrode formed on the semiconductor layer of each thin film transistor for each pixel and a gate line connected to the gate electrode and formed in one direction are formed together in the display region.

Next, a second insulating layer 105 is deposited on the first insulating layer 103 including the semiconductor layer 102 and the electrode pattern.

The second insulating layer 105 and the first insulating layer 103 are selectively removed to expose a portion of the source region 102a and the drain region 102c. An open region is formed to open the other region of the electrode pattern so as to leave only the region adjacent to the drain region 102c. During this process, the source / drain regions of the semiconductor layer are also formed for each pixel of the display region.

Next, a metal layer is formed on the second insulating layer 105 including the open region and the contact hole, and selectively removed to form a source electrode 106 and a drain electrode (not shown) connected to the source region and the drain region, respectively 107 are formed. During this process, a source electrode and a drain electrode are formed for each pixel of the display region, and a data line connected to the source electrode and crossing the gate line is formed.

In the step of forming the source electrode and the drain electrode by selectively removing the metal layer, the electrode pattern under the open region is removed together to form the control electrode 104.

A protective film is formed on the entire surface of the second insulating film 105 including the source electrode 106 and the drain electrode 107. A pixel electrode that is in contact with the drain electrode is formed in each thin film transistor of each pixel of the display region More.

On the other hand, data evaluating the degree of photocurrent sensing of a photosensor of a display device formed by the proposed method of the present invention will be introduced below.

Figs. 4 to 7 are graphs showing the relationship between W / L of the semiconductor layer and the display device of the present invention, under the conditions of 32 占 퐉 / 8 占 퐉, 32 占 퐉 / 16 占 퐉, 32 占 퐉 32 占 퐉 and 32 占 퐉 / And the photoelectric current of the photoelectric sensor of the photosensor of FIG.

That is, experiments were conducted by changing the conditions of L, 8 μm, 16 μm, 32 μm and 64 μm, respectively, in the semiconductor layer shown in FIG. 3 while maintaining the same condition of W of 32 μm. Here, the source electrode side was grounded (0V).

Here, it can be seen that, in each experiment, when a bias voltage having a specific positive voltage is applied to the control electrode in all cases regardless of the size of the semiconductor layer, a period in which the photocurrent linearly changes occurs at the positive voltage, , It can be seen that the linearly varying section is a section similar to the positive constant voltage applied to the control electrode by the drain-source voltage Vds.

Further, the shorter the length of the L (the length of the intrinsic region where the control electrode is not formed in the intrinsic region) is, the narrower the linear region in which the photocurrent changes is. This means that the slope at which the photocurrent value changes with respect to Vds becomes steep. That is, when the length of the semiconductor layer is long, the photocurrent changes in a wide range of the variation width of Vds. When the length of the semiconductor layer is short, the photocurrent changes in a narrow range of the variation width of Vds.

In any case, since the detected photocurrent value is as low as 10 ^-8 A or less, it may be preferable to provide an amplifier in the photocurrent detecting portion of the photosensor. Accordingly, the photocurrent sensing of the corresponding portion can be performed, and the luminance according to the external light can be discriminated.

Here, when the control electrode is placed in a floating state, it is difficult to find a linear region. This means that it is difficult to measure the photocurrent characteristic. On the other hand, in the case of a positive constant voltage such as 5V and 10V, It can be seen that a photocurrent having a linear characteristic can be found in Vds.

That is, when a voltage is applied to the control electrode of the photosensor, a photocurrent rapidly increases as the voltage Vds between the drain electrode and the source electrode increases. The voltage Vds across the device when the photocurrent begins to increase sharply is similar to the voltage across the control electrode. In addition, the photocurrent generated regardless of whether the voltage applied to the control electrode is 5V or 10V is almost the same, and if the control electrode is floated, it is difficult to use it as a photosensor because there is no voltage section in which the photocurrent appears.

That is, the photosensor of the display device of the present invention is provided with appropriate bias condition and control electrode deflected in the drain region to enable optical sensing.

In the photosensor of the display device of the present invention described above, the doping region of the semiconductor layer is a p + -type or n + -type and only one impurity of the conductive type is used. Thus, the masking process is reduced.

In addition, the current-voltage characteristic is changed according to the voltage condition applied to the control electrode, and the optical sensing can be performed using the same, which is advantageous for application as a device and can be used in various applications for sensing light, You can use it.

For convenience of measurement, the length of the semiconductor layer is increased, and the photocurrent sensing can be performed in a wide section of Vds.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Will be apparent to those of ordinary skill in the art.

1 is a cross-sectional view of a conventional photo sensor

2 is a cross-sectional view showing the photosensor of the display device of the present invention

FIG. 3 is a plan view of the semiconductor layer of FIG.

Figs. 4 to 7 are graphs showing the relationship between W / L of the semiconductor layer and the display device of the present invention, under the conditions of 32 占 퐉 / 8 占 퐉, 32 占 퐉 / 16 占 퐉, 32 占 퐉 32 占 퐉 and 32 占 퐉 / A graph showing the relationship between Vds and photocurrent according to the voltage applied value to the control electrode of the photo sensor of FIG.

Description of the Related Art [0002]

100: substrate 101: buffer layer

102: semiconductor layer 102a: source region

102b: intrinsic region 102c: drain region

103: first insulating film 104: control electrode

105: second insulating film 106: source electrode

107: drain electrode 108: protective film

Claims (15)

delete delete delete delete delete delete delete delete delete Preparing a substrate which is divided into a display region and a non-display region and has a light-receiving region in which a part of the non-display region receives external light; Forming a semiconductor layer on the light receiving region by low-temperature crystallization; Forming a first insulating film on the substrate including the semiconductor layer; Forming an electrode pattern covering the center of the semiconductor layer and forming a source region and a drain region by doping the semiconductor layer on both sides of the electrode pattern with the first type impurity using the electrode pattern as a mask, Defining an area of the semiconductor layer that is obscured as an intrinsic area; Depositing a second insulating layer on the first insulating layer including the semiconductor layer and the electrode pattern; A contact hole for selectively removing the second insulating film and the first insulating film to expose a part of the source region and the drain region; and a second insulating film formed on the semiconductor substrate, Forming an open region that covers only a part where the region contacts and opens the remaining region; Forming a metal layer on the second insulating film including the open region and the contact hole and selectively removing the metal layer to form a source electrode and a drain electrode connected to the source region and the drain region in each of the contact holes, And forming a control electrode which is not overlapped with the drain electrode by removing an electrode pattern under the region. delete 11. The method of claim 10, Wherein the first type impurity is p + type. 11. The method of claim 10, Wherein the contact hole and the open region are formed by a single mask. 11. The method of claim 10, And a shielding layer is further formed under the semiconductor layer. 11. The method of claim 10, Wherein the display region includes a gate line and a data line intersecting with each other, and a thin film transistor including a pixel portion semiconductor layer formed of polysilicon formed at an intersection of the gate line and the data line, The semiconductor layer is formed on the same layer as the pixel portion semiconductor layer, The control electrode is formed on the same layer as the gate line, Wherein the source electrode and the drain electrode are formed on the same layer as the data line.

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