CN101308866A - Flat panel display with improved white balance and method of manufacturing the same - Google Patents

Abstract

The invention discloses a flat panel display, comprising a plurality of pixels, each of which includes R, G and B unit pixels to express red (R), green (G) and blue (B) respectively, and each of the The unit pixel includes a transistor, wherein the transistor of at least one of the R, G, and B unit pixels includes a channel region made of silicon layers having different film properties. The invention also relates to methods of manufacturing flat panel displays.

Description

Flat panel display with improved white balance and method of manufacturing the same

This application is a divisional application of Invention Patent Application No. 200410032887.9 filed on April 13, 2004, and claims the priority of Korean Patent Application No. 2003-24503 and No. 2003-24429 filed on April 17, 2003 , the disclosure of which is hereby incorporated by reference in its entirety.

technical field

The present invention relates to a full-color flat-panel display, especially by using the MIC/MILC process to make the channel layers of the drive transistors in each R, G and B unit pixel have different current mobilities (current mobilities). White balanced flat panel display and method of manufacturing the same.

Background technique

Generally, as shown in FIG. 1 , an organic light emitting diode (OLED) of a flat panel display includes a plurality of pixels 100 arranged in a matrix. Each pixel 100 is composed of three unit pixels, that is, a unit pixel 110R representing red (R), a unit pixel 120G representing green (G), and a unit pixel 130B representing blue (B). .

The R-unit pixel 110R includes: a red electroluminescence (EL) device 115 including a red (R) light emitting layer; a driving transistor 113 for supplying current to the red EL device 115; and A switching transistor 111 for switching the current supplied from the driving transistor 113 to the red EL device 115 .

The G-unit pixel 120G includes: a green EL device 125 including a green (G) light emitting layer; a driving transistor 123 for supplying current to the green EL device 125; The driving transistor 123 supplies the current to the green EL device 125 to the switching transistor 121 .

The B-unit pixel 130B includes: a blue EL device 135 including a blue (B) light emitting layer; a drive transistor 133 for supplying current to the blue EL device 135; The switching transistor 131 of the current supplied from the driving transistor 133 to the blue EL device 135 .

Conventionally, the drive transistors 113, 123, and 133 of the R, G, and B unit pixels 110R, 120G, and 130B of an OLED device have the same size, that is, the same ratio W of the width W to the length L of the channel layer. /L, and in the order of their luminous efficiencies, the order of the EL devices is B, R and G unit pixels. In the conventional OLED, since the channel layers of the driving transistors 113, 123, and 133 of the R, G, and B unit pixels 110R, 120G, and 130B have the same size, the EL devices of the R, G, and B The luminous efficiencies of 115, 125, and 135 are different from each other, so it is difficult to achieve white balance.

In order to realize the white balance, a relatively small amount of current should be supplied to EL devices having high luminous efficiency such as green EL devices, and a relatively large amount of current should be supplied to red and blue EL devices having lower luminous efficiencies. current.

Here, since the current Id flowing to the EL device through the driving transistor starts to flow when the driving transistor is in a saturated state, the current is expressed as follows:

(1)Id=CoxμW(Vg-Vth) ² /2L

Therefore, one way to control the current flow to the EL device for white balance is to make the dimensions of the drive transistors of the R, G, and B unit pixels (that is, the width W and length L of the channel layer The ratio W/L) is different, and thus controls the amount of current flowing to the EL devices of the R, G, and B unit pixels. A method of controlling the amount of current flowing to the EL device according to the size of the transistor is disclosed in Japanese Laid-Open Patent Publication No. 2001-109399. In this Japanese patent, the sizes of the driving transistors of the R, G and B unit pixels are formed differently according to the luminous efficiency of the EL device in each of the R, G and B unit pixels. That is, by making the size of a driving transistor of a unit pixel expressing green (G) having high luminous efficiency smaller than that of a unit pixel expressing red (R) or blue (B) having relatively low luminous efficiency, to control the amount of current flowing to the EL devices of the R, G, and B unit pixels.

Another method of achieving the white balance is to make the sizes of the light emitting layers of the R, G, and B unit pixels different, which is disclosed in Japanese Laid-Open Patent Publication No. 2001-290441. In this Japanese patent, the same luminescence is generated from the R, G and B unit pixels by making the light emitting areas different according to the luminous efficiencies of the EL devices of the R, G and B unit pixels. That is, the same light emission is generated on the R, G, and B unit pixels by making the light emitting area of the R or B unit pixel having low luminous efficiency larger than that of the G unit pixel having relatively high luminous efficiency.

However, in the above-mentioned conventional method for achieving white balance, the light-emitting area of the unit pixel with low light-emitting efficiency among the R, G, and B unit pixels becomes large, or the light-emitting area of the unit pixel with low light-emitting efficiency among the R, G, and B unit pixels is increased. Luminous efficiency unit pixel transistor size. This causes a problem that the charging area per unit pixel increases, and thus it is not easy to apply the present invention to a high-resolution display.

Contents of the invention

An aspect of the present invention is to provide a flat panel display and a method of manufacturing the same, in which white balance can be achieved without increasing the area of pixels.

Another aspect of the present invention is to provide a flat panel display and a manufacturing method thereof, wherein white balance can be achieved by making channel layers of driving transistors in R, G, and B unit pixels have different current mobility.

Still another aspect of the present invention is to provide a flat panel display and a method of manufacturing the same, wherein white balance can be achieved by crystallizing channel layers of driving transistors in R, G, and B unit pixels in different directions.

Still another aspect of the present invention is to provide a flat panel display and a manufacturing method thereof, wherein white balance can be achieved by making resistance values of channel layers of driving transistors in R, G, and B unit pixels different.

Still another aspect of the present invention is to provide a flat panel display and a manufacturing method thereof, wherein by making the length of an amorphous silicon film included in the channel layer of the driving transistor of each of R, G, and B unit pixels different, White balance can be achieved.

According to an exemplary embodiment of the present invention, there is provided a flat panel display including a plurality of pixels, wherein each pixel includes R, G and B unit pixels to express red (R), green (G) and blue (B) respectively. ), and each unit pixel includes at least one transistor, wherein the transistors of at least two unit pixels among the R, G, and B unit pixels include channel layers different in current mobility.

At least one transistor in the R, G, and B unit pixels includes a channel layer having the same size on each pixel. The R, G, and B unit pixels include light emitting devices, respectively. A transistor controlling current supplied to a light emitting device of each unit pixel includes a channel layer having the same size on each pixel, and is used to drive a light emitting device having the highest luminous efficiency among light emitting devices having the unit pixel. The current mobility of the transistor is smaller than that of a transistor for driving a light emitting device having relatively low luminous efficiency.

The channel layers of the transistors of the R, G, and B unit pixels may be made of polysilicon films having crystallization directions different from each other. A channel layer for driving a transistor of a light-emitting device having the highest luminous efficiency among the light-emitting devices may be made of a metal induced crystallization (MIC) polysilicon film, and used for driving a light-emitting device having a relatively low luminous efficiency. A channel layer of a transistor of a light emitting device may be made of a metal induced lateral crystallization (MILC) polysilicon film.

The R, G, and B unit pixels may further include light emitting devices driven by the transistors, respectively, and the R, G, and B unit pixels include a driving transistor for driving the light emitting devices and a driving transistor for turning on or off switch transistor off the drive transistor.

Channel layers of the switching transistors of the R, G, and B unit pixels may be made of an MIC polysilicon film. The driving transistor of the unit pixel having the highest luminous efficiency among the R, G, and B unit pixels has a channel layer made of MIC polysilicon film, and the driving transistor of the unit pixel having relatively low luminous efficiency has a channel layer made of MILC polysilicon film. Membrane made of channel layer.

The channel layers of the switching transistors of the R, G, and B unit pixels may be made of MILC polysilicon film, and the driving transistors having the highest luminous efficiency among the R, G, and B unit pixels may have a layer made of MIC polysilicon film. film, while the driving transistor of a unit pixel having relatively low luminous efficiency may have a channel layer made of MILC polysilicon film.

The switching transistor and the driving transistor of the unit pixel having the highest luminous efficiency among the R, G, and B unit pixels may have a channel layer made of MIC polysilicon film, and the driving transistor and the switching transistor of the unit pixel having relatively low luminous efficiency The transistor may have a channel layer made of MILC polysilicon film.

Also, in a flat panel display including a plurality of pixels, wherein each of said pixels includes R, G, and B unit pixels, and each of said unit pixels includes at least one transistor, a method of manufacturing the flat panel display is provided , comprising forming an amorphous silicon film on an insulating substrate and forming a first and a second MILC mask on the amorphous silicon film. The method further includes: depositing a metal film for MILC on the substrate; crystallizing the amorphous silicon film into a polysilicon film so that a portion corresponding to the first and second masks passes through the MILC method crystallization and the remaining portion is crystallized by the MIC method; the first and second masks and the metal film are removed; and the polysilicon film is patterned so as to have the highest luminous efficiency among the R, G, and B unit pixels The semiconductor layer of the transistor of one unit pixel is made of a polysilicon film crystallized using the MIC method, and the semiconductor layer of the transistor of a unit pixel having relatively low luminous efficiency is made of a polysilicon film crystallized using the MILC method.

Also, a flat panel display is provided, comprising a plurality of pixels, each of which includes R, G and B unit pixels to represent red (R), green (G) and blue (B) respectively, each of said unit The pixel includes a transistor, wherein the transistor of at least one unit pixel among the R, G, and B unit pixels includes a channel region made of silicon layers having different film properties.

Transistors of at least two unit pixels among the R, G, and B unit pixels include channel regions made of at least one silicon layer having different film properties, and the transistors having low current mobility in the channel regions The silicon layers vary in length.

The R, G, and B unit pixels include light emitting devices, respectively, and the channel region of the transistor corresponding to the light emitting device having the lowest luminous efficiency among the light emitting devices of the R, G, and B unit pixels does not include a The silicon layer with low current mobility, or including the silicon layer with low current mobility, has a length smaller than that of a channel region of a transistor corresponding to a light emitting device with relatively high luminous efficiency.

The channel region is made of a polysilicon layer and an amorphous silicon layer, and the silicon layer having low current mobility in the channel region is made of an amorphous silicon layer.

Likewise, in a flat panel display including a plurality of pixels, each of said pixels includes R, G, and B unit pixels to represent red (R), green (G) and blue (B), respectively, and each of said unit A pixel includes one transistor, a unit pixel, and each unit pixel includes a transistor. There is provided a method of manufacturing the flat panel display, comprising: forming an amorphous silicon film on an insulating substrate, forming first to third masks for MILC on the amorphous silicon film, and A metal film for MILC is deposited on the substrate. The method further includes crystallizing the amorphous silicon film into a polysilicon film so that the amorphous silicon film is only partially kept under the first to third masks, removing a mask for MILC. first to third masks and metal films for MILC, and patterning the polysilicon film so that the amorphous silicon film existing between the polysilicon films forms the R, G and B units The semiconductor layer on the transistor of the pixel, wherein the resistance value of the channel region of the transistor of the R, G and B unit pixel is determined by the length of the amorphous silicon film existing between the polysilicon films.

Description of drawings

The above-mentioned and other features and advantages of the present invention will be more apparent to those skilled in the art by describing the embodiments in detail and referring to the accompanying drawings.

Fig. 1 is the distribution figure of R, G and B unit pixel of a conventional flat panel display;

2A, 2B, 2C and 2D are views of a method of manufacturing driving transistors of R, G and B unit pixels according to an embodiment of the present invention;

Figure 3 shows the relationship between gate voltage and drain voltage according to the MIC/MILC crystallization method;

4A, 4B, 4C and 4D are cross-sectional views of a method of manufacturing driving transistors of R, G and B unit pixels according to another embodiment of the present invention.

Detailed ways

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings showing embodiments of the invention. However, the present invention may be embodied in different forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the thicknesses of layers and regions are exaggerated for clarity. Throughout the specification, the same reference numerals refer to the same parts.

2A, 2B, 2C and 2D are views of a method of manufacturing driving transistors of R, G and B unit pixels according to an embodiment of the present invention. 2A, 2B, 2C and 2D are cross-sectional structures showing driving transistors in the R, G and B unit pixels of each pixel in an organic light emitting diode.

Referring to FIG. 2A, an unshown buffer layer is formed on an insulating substrate 200, and an amorphous silicon film 210 is formed on the buffer layer. A plurality of masks 221 and 225 for MILC are formed on the amorphous silicon film 210, and a metal film 230 is formed on the entire substrate surface.

The masks 221 and 225 for MILC are formed on regions 201 and 205 corresponding to the R and B unit pixels to be formed. Since a mask for MILC is not formed on the region 203 where G-unit pixels are to be formed, the metal film 230 is formed in direct contact with the amorphous silicon film 210 . Although an oxide film is used as the MILC masks 221 and 225 in the present invention, other films such as a photosensitive film may be substituted for the oxide film.

Referring to FIG. 2B, the amorphous silicon film 210 is crystallized into a polysilicon film 240 by performing a crystallization process. Here, the polysilicon film 240 is formed by the MIC and MILC methods, wherein a portion 241 of the polysilicon film 240 corresponding to the mask 221 is crystallized by the MILC method, and a portion 245 corresponding to the mask 225 is also crystallized by the MILC method. The portion 243 directly in contact with the metal film 230 , that is, the remaining portion 243 including the region 203 where the G unit pixel is to be formed, is completely crystallized by the MIC method.

Referring to FIG. 2C, after removing the masks 221 and 225 and the metal film 230 for MILC, the polysilicon film is processed by using a mask (not shown) for forming the semiconductor layer of the driving transistor. 240 patterning to form the semiconductor layers 251, 253 and 255 of the driving transistors of the R, G and B unit pixels. Here, the sizes of the semiconductor layers 251, 253, and 255 of the driving transistors of the unit pixel are all the same.

In the R, G, and B unit pixels, the semiconductor layer 251 of the drive transistor of the R unit pixel is composed of the polysilicon film 241 crystallized by the MILC method. The semiconductor layer 253 of the driving transistor of the G unit pixel is composed of the polysilicon film 243 crystallized by the MIC method. The semiconductor layer 255 of the driving transistor of the B unit pixel is composed of the polysilicon film 245 crystallized by the MILC method.

Referring to FIG. 2D, a gate insulating film 260 is formed on the substrate including the semiconductor layers 251, 253, and 255, and gates 271, 273 of the driving transistors of each unit pixel are formed on the gate insulating film 260. and 275. The source/drain regions 281, 281, 281, 283 and 285.

Although not shown in the drawings, an interlayer insulating film may be formed on the entire surface of the substrate. Contact holes for exposing the source/drain regions 281, 283 and 285 may be formed by etching the interlayer insulating film and the gate insulating layer 260, and a contact hole passing through the contact holes and the source/drain regions may be formed. 281, 283 and 285 are electrically connected source/drain regions, thus fabricating the drive transistor.

In the flat panel display of the present invention manufactured using the above method, the driving transistors of the R, G, and B unit pixels may include channel layers having the same lengths Lrc, Lgc, and Lbc. The driving transistors of the R and B unit pixels may include channel layers made of polysilicon films 241 and 245 crystallized by the MILC method, respectively, and the driving transistors of the G unit pixel may include polysilicon films 241 and 245 crystallized by the MIC method. 243 channel layer. Accordingly, the driving transistors of the R, G, and B unit pixels may have channel layers of the same size. Also, current mobility of the channel layer may vary according to crystallization directions of the channel layers of the driving transistors of the R, G, and B unit pixels.

The channel layers of the drive transistors of the R and B unit pixels having low luminous efficiency may be made of polysilicon films 241 and 245 crystallized by the MILC method having high current mobility, while those having higher luminous efficiency The channel layer of the driving transistor of the G-unit pixel may be made of a polysilicon film 243 crystallized by the MIC method having low current mobility.

Therefore, according to an embodiment of the present invention, by changing the crystallization direction of the channel layer according to the luminous efficiencies of the EL devices of the R, G, and B unit pixels, the resistance value of the channel layer can be determined, with a relative The channel layers of the drive transistors of the R and B unit pixels with low luminous efficiency are made of a polysilicon film crystallized according to the MILC method, which has a crystallization direction in the same direction as the channel length, that is, a horizontal direction, And thus have a rather low resistance value. Also, the channel layer of the drive transistor of the G unit pixel having relatively high luminous efficiency is made of a polysilicon film crystallized according to the MIC method, which has a crystallization direction perpendicular to the channel length direction, that is, the vertical direction , and thus have a rather high resistance value.

Therefore, the white balance of the present invention can be achieved by making the channel layers of the R, G, and B unit pixels the same size and making their crystallization directions different, and thus making current mobility different from each other.

FIG. 3 is a view showing a relationship between a gate voltage and a drain voltage of a thin film transistor including a semiconductor layer crystallized by MIC and MILC methods. FIG. 3 shows that even when the thin film transistors have the same size (W/L) and channel direction, the amount of current may differ depending on the fine structure of the polysilicon film of the channel layer.

Referring to FIG. 3, it should be noted that the characteristic curve of the drain current versus the gate voltage in the MILC polysilicon thin film transistor is better than the characteristic curve of the drain current versus the gate voltage in the MIC polysilicon thin film transistor. Therefore, the current mobility of the thin film transistor made of the polysilicon film crystallized by the MILC method is higher than that of the thin film transistor made of the polysilicon film crystallized by the MIC method.

Therefore, in one embodiment of the present invention, the channel layer of the drive transistor of the green unit pixel with relatively high luminous efficiency is made of MIC polysilicon film, and the red and blue unit pixels with relatively low luminous efficiency The channel layer of the drive transistor of the color unit pixel is made of MILC polysilicon film. White balance may be achieved by making the current flowing through the driving transistor of the red or blue unit pixel higher than the current flowing through the driving transistor of the green unit pixel.

In one embodiment of the present invention, even if the channel layer of the driving transistor is formed of a polysilicon film crystallized by the MIC and/or MILC method according to the luminous efficiencies of the EL devices of the R, G, and B, the MIC and/or Or the MILC method can also be applied to the switch transistors of the R, G and B unit pixels. For example, the channel layers of the switching transistors of all the R, G, and B unit pixels may be composed of a polysilicon film crystallized by the MIC method and/or the MILC method. Alternatively, the switching transistor of the G unit pixel having higher luminous efficiency may have a channel layer composed of a polysilicon film crystallized by the MIC method, while the switching transistor of the R or B unit pixel having lower luminous efficiency The transistor may have a channel layer composed of a polysilicon film crystallized by the MILC method. The semiconductor layers of the driving transistors and the switching transistors of the R, G, and B unit pixels may have the same crystallization direction as or different from a channel direction.

Even though the channel layer of one embodiment of the present invention is described as being crystallized by the MIC/MILC method, the channel layers of the driving transistors of the R, G, and B unit pixels may have different crystallization methods from each other, So that all crystallization methods having different current mobility from each other can be used in the present invention.

4A, 4B, 4C and 4D are process cross-sectional views of a method of manufacturing driving transistors for R, G and B unit pixels according to another embodiment of the present invention. 4A, 4B, 4C and 4D are cross-sectional structures showing driving transistors of the R, G and B unit pixels of each pixel in an organic light emitting diode.

Referring to FIG. 4A, although not shown in the drawing, a buffer layer is formed on an insulating substrate 400, and an amorphous silicon layer 410 is formed on the substrate. A plurality of masks 421, 423 and 425 for MILC are formed on the amorphous silicon layer 410 and a metal layer 430 is formed on the entire substrate surface.

The masks 421, 423, and 425 for MILC are formed to have different widths from each other, wherein the order of the mask widths from high to low is the second mask 423, the first mask 421, and the third mask. Modulo 425. The first mask 421 is formed in a region where the driving transistor (113 in FIG. 1 ) of the R unit pixel among the R, G, and B unit pixels is to be formed correspondingly, and the second mask 423 is formed In the area where the driving transistor ( 123 in FIG. 1 ) of the G unit pixel is to be formed. The third mask 425 is formed in a region where the driving transistor ( 133 in FIG. 1 ) of the B-unit pixel is to be formed.

Referring to FIG. 4B, a crystallization process is performed to crystallize the amorphous silicon film 410 into a polysilicon film 440, wherein portions corresponding to the masks 421, 423, and 425 in the amorphous silicon film 410 are crystallized by the MILC method. These become polysilicon films 441 , 443 and 445 . A portion between the masks 421, 423, and 425 that is in direct contact with the metal layer 430 is crystallized using the MIC method to form a polysilicon film 447.

Since the first to third masks 421, 423, and 425 for MILC have different widths from each other, the portion of the polysilicon film 440 corresponding to the third mask 425 having a relatively narrow width is processed by the MILC method. crystallized, and portions corresponding to the first and second masks 421 and 423 having a relatively wide width are partially crystallized by the MILC method, respectively, leaving the amorphous silicon films 411 and 413 unchanged.

That is, in the polysilicon film 440 corresponding to the first mask 421, the amorphous silicon film 411 exists between portions 441 crystallized by the MILC method. Also, in the polysilicon film 440 corresponding to the second mask, the amorphous silicon film 413 exists between portions 443 crystallized by the MILC method. Since the width of the first mask 421 is relatively smaller than the width of the second mask 423, the length of the amorphous silicon film 413 corresponding to the second mask 423 is longer than that corresponding to the first mask. 421 is the length of the amorphous silicon film 411.

Referring to FIG. 4C, after removing the masks 421, 423 and 425 and the metal layer 430 for the MILC method, the polysilicon film 440 is patterned by using a mask (not shown) for forming a semiconductor layer to form Semiconductor layers 451, 453, and 455 for driving transistors of the R, G, and B unit pixels. The portion 441 crystallized by the MILC method in the polysilicon film 440 and the amorphous silicon film 411 existing between the portions 441 form all of the R, G, and B unit pixels. The semiconductor layer 451 of the driving transistor of the R unit pixel. The portion 443 crystallized by the MILC method in the polysilicon film 440 and the amorphous silicon film 413 existing between the portions 443 form the semiconductor for the driving transistor of the G unit pixel. Layer 453. On the other hand, only the polysilicon film 445 crystallized by the MILC method among the polysilicon films forms the semiconductor layer 455 for the driving transistor of the B unit pixel.

Referring to FIG. 4D, a gate insulating film 460 is deposited on the entire surface of the substrate including the semiconductor layers 451, 453 and 455. Referring to FIG. Deposit a conductive material such as a metal film on the film 460, and then use a mask (not shown) for forming the gate to pattern the conductive material to form each of the R, G and Gates 471, 473, and 475 of the driving transistors of the B-unit pixel. Then, using the gates 471, 473 and 475 as masks, implant high-concentration impurity ions of the desired conductivity type into the semiconductor layers 451, 453 and 455 to form the source/drain regions 481, 481, 483 and 485.

Even though not shown in the drawings, the driving transistor can be manufactured by forming an interlayer insulating film on the entire surface of the substrate, by etching the interlayer insulating film and the gate insulating film 460 forms contact holes exposing the source/drain regions 481 , 483 and 485 , and forms source/drain electrodes electrically connected to the source/drain regions 481 , 483 and 485 through the contact holes.

In the flat panel display according to the present invention manufactured by the above method, the channel layer 482 of the driving transistor of the R unit pixel may be made of the polysilicon film 441 and the amorphous silicon film 411 crystallized by the MILC method. The length Lrc of the channel layer is the sum of the lengths Lr1 and Lr2 of the polysilicon film 441 and the length Lra of the amorphous silicon film 411, that is, Lrc=Lr1+Lra+Lr2. The channel layer 484 of the driving transistor of the G unit pixel is made of the polysilicon film 443 and the amorphous silicon film 413 crystallized by the MILC method. The total channel layer length Lgc is the sum of the lengths Lg1 and Lg2 of the polysilicon film 443 and the length Lga of the amorphous silicon film 413, that is, Lgc=Lg1+Lga+Lg2. The channel layer 486 of the driving transistor of the B unit pixel is made of the polysilicon film 445 crystallized only by the MILC method, and the total length Lbc of the channel layer is equal to the length Lb of the polysilicon film 445 .

In the driving transistors of the R, G and B unit pixels, since the lengths of the channel layers 482, 484 and 486 are the same, which is Lrc=Lgc=Lbc, the resistance value of the channel layer of the driving transistor is included in each The length of the amorphous silicon film in each channel layer varies. However, the embodiments of the present invention can be configured to determine the resistance value of the channel layer according to the luminous efficiencies of the EL devices of the R, G, and B unit pixels, because the channel of the B unit pixel with the relatively lowest luminous efficiency The channel layer 486 is made of a polysilicon film crystallized by the MILC method, and its channel layer resistance value is relatively low.

Also, the channel layer 482 or 484 of the R or G unit pixel having relatively high luminous efficiency includes an amorphous silicon film between the polysilicon films, so that the resistance value of the channel layer is relatively increased. Since the EL device of the R unit pixel has lower luminous efficiency than the EL device of the G unit pixel, the length Lra of the amorphous silicon film 411 present in the channel layer 482 of the R unit pixel is limited by It is formed to be relatively shorter than the length Lga of the amorphous silicon film 413 present in the channel layer 484 of the G unit pixel.

Therefore, when the lengths of the channel layers of the driving transistors of the R, G and B unit pixels according to another embodiment of the present invention are formed to be equal, the driving transistors of the R, G and B unit pixels The amorphous silicon films present in the channel layer are formed to have different lengths from each other. Therefore, white balance can be achieved by making the resistance values of the channel layers of the driving transistors different from each other.

According to another embodiment of the present invention, the driving transistors of the R, G and B unit pixels are changed by performing crystallization treatment so that the amorphous silicon film exists in the channel layer by the MILC treatment. The resistance value of the channel layer. However, by changing the resistance values of the drive transistors of the R, G, and B unit pixels by making the channel layer include amorphous silicon films having different lengths from each other by using other crystallization processing instead of the MILC process, the Methods can also be used in the present invention. Although the amorphous silicon film may not exist in the channel layer of the driving transistor of the B-unit pixel, the present invention is not limited to the above-mentioned structure. Rather, the present invention may even be formed as a structure including an amorphous silicon film having a resistance value at a level enabling white balance of the channel layer of the R or G unit pixel.

According to another embodiment of the present invention, by controlling the crystallization temperature or crystallization time during MILC crystallization, a crystallization process can be performed so that an amorphous silicon film exists in each channel layer. All channel regions of switching transistors of the unit pixel may be formed with the MILC polysilicon film. The driving transistors of the R and G unit pixels have an amorphous silicon film between the polysilicon films, and the driving transistor of the B unit pixel may have a channel region made of polysilicon film.

In the above description of the present invention, the white balance is not achieved by increasing the pixel area, but by changing the current mobility or resistance value of the channel layer of the R, G and B unit pixels. balance.

Also, by crystallizing an amorphous silicon film into the polysilicon film using the MIC/MILC crystallization method, and thus forming the semiconductor layers of the driving transistors of the R, G, and B unit pixels having different current mobility, the present invention The process cost can be reduced and the process can be simplified.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those of ordinary skill in the art will appreciate that various modifications, additions and and substitute.

Claims (8)

1. a flat-panel monitor comprises a plurality of pixels, and each described pixel comprises R, G and B unit picture element with express red (R), green (G) and blueness (B) respectively, and each described unit picture element comprises a transistor,

The transistor of at least one unit picture element comprises the channel region of being made by the silicon layer with different film properties among wherein said R, G and the B unit picture element.

2. flat-panel monitor according to claim 1, the described transistor of at least two unit picture elements comprises the channel region of being made by the silicon layer with at least a different film properties in wherein said R, G and the B unit picture element, and wherein said length difference with silicon layer of low channel region current transfer rate.

3. flat-panel monitor according to claim 1, the transistor of wherein said R, G and B unit picture element comprises the channel layer with equal length.

4. flat-panel monitor according to claim 1, wherein each described R, G and B unit picture element also comprise a light emitting devices respectively, and control comprises the channel layer with equal length to the transistor of the light emitting devices supply of current of described unit picture element.

5. as flat-panel monitor as described in the claim 4, wherein do not comprise silicon layer with low current mobility corresponding to the transistorized channel region that among the light emitting devices of described R, G and B unit picture element, has the light emitting devices of minimum luminous efficiency, or comprise have the low current mobility, its length is than the littler described silicon layer of length corresponding to the transistorized channel region of the light emitting devices with relative high-luminous-efficiency.

6. as flat-panel monitor as described in the claim 3, wherein said channel region is made by a polysilicon layer and a noncrystallineization silicon layer.

7. as flat-panel monitor as described in the claim 3, the described silicon layer that wherein has the low current mobility in described channel region is made by described noncrystallineization silicon layer.

8. method of making flat-panel monitor, described flat-panel monitor comprises a plurality of pixels, each pixel comprises R, G and B unit picture element with express red (R), green (G) and blueness (B) respectively, and each described unit picture element comprises a transistor, and described method comprises:

On a dielectric substrate, form a noncrystalline silicon fiml,

On described noncrystalline silicon fiml, be formed for first mask to the, three masks of metal induced lateral crystallizationization;

Deposit is used for the metal film of metal induced lateral crystallizationization on described substrate;

It is a polysilicon film that described amorphous silicon membrane crystallization is changed into, so that described noncrystalline silicon fiml only partly remains under described first to the 3rd mask;

Remove described first to the 3rd mask and described metal film; And

Described polysilicon film is carried out composition, so that between described polysilicon film, exist noncrystalline silicon fiml to form the transistorized semiconductor layer of described R, G and B unit picture element.

The transistorized channel region of wherein said R, G and B unit picture element has the resistance value by the length decision of the noncrystalline silicon fiml that exists between described polysilicon film.

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