Active solid-state devices (e.g. – transistors – solid-state diode – Thin active physical layer which is – Heterojunction
Reexamination Certificate
2001-03-20
2004-04-27
Eckert, George (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Thin active physical layer which is
Heterojunction
C257S059000, C257S063000, C257S072000, C257S628000
Reexamination Certificate
active
06727514
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin-film semiconductor integrated circuit, a picture display device with using thereof, such as a liquid crystal display device, etc., and a manufacturing method thereof.
2. Description of Prior Art
In recent years, attention was paid upon a thin-film semiconductor integrated circuit, in which circuits are constructed by forming a plural number of thin-film transistors (hereinafter, abbreviated by “TFT”) on a single glass substrate. As an example of an application thereof can be listed up display devices, such as a liquid crystal display device, an EL (electro luminescence) display device, etc.
Conventionally, in particular, in a case of a picture display device, although a picture display portion of, such as pixel portions, etc., can be formed on a glass plate, however other portions for driving the picture display portion must be formed on an ordinary print circuit board, i.e., peripheral circuit portions, such as, a source driver, a gate driver, a shift register, a peripheral controller, etc., and this must be connected to the glass substrate by means of a cable terminal(s), thereby to be used. With such the method, there are pointed out drawbacks that the screen is small in sizes (i.e., from 4 inches to 10 inches), and that the costs also come to be high of the apparatus as a whole.
As a solution of such the drawbacks, it is possible to increase up the screen size greatly by forming the picture display portion and the driver, etc., on a signal substrate in one body, thereby to realize a picture display device, such as, a large screen wall hang television and/or monitor for a personal computer of high performances. However, for processing a large amount of information signals for a high-definition picture display portion, it is very important problem to improve driving capacities of the peripheral circuit portions, such as the driver, etc.
Accordingly, in order to improve the performances (in particular, electron mobility) of TFTs constructing the peripheral circuit portions, such as the driver, etc., extremely, it is necessary to prevent carriers from scattering on grain boundary by an improvement in a crystal property within an active region or area of those TFTs, and thereby to realize a high mobility.
However, for crystallization of Si film on the glass substrate, the crystallization must be performed under temperature being lower than a temperature (about 450° C.) of generating distortion within the glass substrate, however the crystallization will not occur under such the low temperature, such as about 450° C.
In recent years, as a means provided for dissolving such the problem, there are listed up a laser annealing method and a crystallization accelerating method, etc.
The laser annealing method is a one, wherein a amorphous crystalline or a fine crystalline Si thin-film, which is formed on the glass substrate by a decompression CVD method, etc., is melt and re-crystallized by using an eximer laser, and with this it is possible to form polysilicon Si having a particle diameter of around to 100 &mgr;m under the temperature lower than 450° C. However, axes of those crystals are in disorder and the surface scattering is large on the grain boundary which exists within the active region of the TFT, therefore, accompanying with this, the electron mobility comes to be large. For example, an electron effective mobility is about from 30 to 50 cm
2
/Vs (Japanese Patent Laying-Open No. Hei 9-27452 (1997)), and this is low comparing to that of the single crystal Si, about 500 cm
2
/Vs (S. M. Sze, Physics of Semiconductor Devices, P. 29, Second Edition, Wiley).
Also, in the Si thin-film on a insulator substrate having a high crystallizing temperature, a catalyst element introduction method is proposed as a means, for reducing down the crystallizing temperature thereof. For an example, a method wherein crystal nucleus is formed on the insulator substrate, on which is formed amorphous crystal silicon in a solid phase (Japanese Patent Laying-Open No. Hei 8-316485 (1996)), a method wherein on a polysilicon are formed accumulated layers of amorphous crystal silicon, on which is formed an exposed polysilicon, as the nucleus for a next crystal growth (Japanese Patent Laying-Open No. Hei 8-31749 (1996)), a method wherein a partially crystallized silicon thin-film is amorphous crystallized selectively by ion implantation while the remaining crystalline portion is grown into crystal, again as the nucleus (Japanese Patent Laying-Open No. Hei 10-55960 (1998)), a method of accelerating a speed of crystallization by means of diffusion of metal elements (Japanese Patent Laying-Open No. Hei 9-27452 (1997), Japanese Patent Laying-Open No. Hei 10-64819 (1998) and Japanese Patent Laying-Open No. Hei 11-186164 (1999)) and a method of varying irradiation energy and irradiation time in a manner of step-like (Japanese Patent Laying-Open No. Hei 10-97993 (1998)), etc.
In particular, in a case where a metal, such as Ni, etc., there is a problem that the metal added remains within the active region of the TFT, thereby decreasing down the performance of the TFTs extremely (in particular, a great increase in an Off current). As a means for dissolving such the problem, a high-temperature processing (600-900° C.) is proposed, being so-called a gettering for removing the remaining metals therefrom. Because of this gettering temperature, the substrate to be used therein must be one of high cost, such as, quartz or crystallized glass, etc., having high temperature resistance, (for example, being disclosed in Japanese Patent Laying-Open No. Hei 11-87243 (1999), Japanese Patent Laying-Open No. Hei 11-186563 (1999), Japanese Patent Laying-Open No. Hei 11-191628 (1999), and Japanese Patent Laying-Open No. Hei 10-135469 (1998)), and as a result, there is an anxiety that it comes off the inherent object, i.e., a low-temperature process with low cost.
Furthermore, as another approach than the mentioned above, an idea is disclosed, wherein taking into the great consideration a high-speed operation characteristic, polysilicon germanium is used as the active layers of the TFTs, which construct the driver circuit and the signal processing circuit, in Japanese Patent Laying-Open No. Hei 11-251600 (1999).
Any one of those various methods for crystallization cannot be said to be a technology being fully complicated, therefore the maximum particle diameter attained is still small and a control is insufficient on positions of the crystal particles. It falls short of a practical size of about 8 &mgr;m of the thin-film transistors, which are required for a liquid crystal panel of a large screen, and it is difficult to suppress unevenness or fluctuation in a distance between elements, due to positional shift of the crystal particles. Furthermore, directions of planes on the formed poly-crystal are in disorder, therefore the electron mobility depending upon the plane direction varies between the elements. Because of this, it does not comes up to a condition those technologies substitute the existing thin-film transistor devices.
SUMMARY OF THE INVENTION
An object, according to the present invention, is to provide an improved thin-film semiconductor integrated circuit device and a picture display device using thereof.
Also, another object, according to the present invention, is to provide a manufacturing method for manufacturing such the thin-film semiconductor integrated circuit device, easily and with good repetitiveness.
Explaining briefly on representative ones of various inventions disclosed in the present application, they are as follows:
Namely, according to one of the present invention, there is provided a thin-film semiconductor integrated circuit, comprising: a insulator substrate, such as of glass; a plural number of semiconductor single crystal portions accumulated on the insulator substrate, being divided and disposed in a matrix manner; and thin-film semiconductor circuit elements, each having activated region on a surface of tha
Nakagawa Kiyokazu
Park Seong-kee
Sugii Nobuyuki
Yamaguchi Shin'ya
Eckert George
Nguyen Joseph
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