JP2002280563A - Tft-type liquid crystal display and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure and manufacturing method for transistors for attaining a TFT-type liquid crystal display using a polycrystal silicon film wherein its transistors are made fine and the density of the transistors is made high. SOLUTION: After forming a first insulation film 14 on the surface of a first semiconductor layer 12 and forming thereon a gate electrode 15, a second insulation layer 16 is so formed as to cover the gate electrode 15 with it. Then, after forming openings through some portions of the first and second insulation layers 14, 16, a second semiconductor layer 17 connected to some portions of the first semiconductor layer 12 is so formed as to obtain field effect (MIS) type semiconductor transistors. Thereby, the transistors can be formed efficiently in parallel with each other on the upper and lower sides of the single gate electrode 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a thin film transistor (TFT) type liquid crystal display device and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, thin film transistor (TFT) type liquid crystal display devices have been widely used in personal computers, electronic cameras, and the like. ing. Further, in order to further improve the characteristics, the development of a transistor using an amorphous silicon film to a transistor using a polycrystalline silicon film has been advanced, and in recent years, it has both an N-channel transistor and a P-channel transistor incorporating peripheral circuits. Complementary field effect semiconductor (CMOS) types are becoming mainstream.

Hereinafter, a method of manufacturing a conventional TFT type liquid crystal display device using a polycrystalline silicon film will be described with reference to the drawings.

FIGS. 2A to 2C are cross-sectional views schematically showing a method of manufacturing a TFT type liquid crystal display device using a conventional polycrystalline silicon film. First, the TFT element is formed on the glass substrate 1
After a polycrystalline silicon film pattern 2 having a thickness of about 60 nm and a gate insulating film 3 having a thickness of about 100 nm are formed on the surface thereof (FIG. 2A), an aluminum (Al) film having a thickness of about 300 nm is formed. Then, the gate wiring pattern 4 of the transistor
And about 3 × 10 ¹⁵ phosphorus / cm ² of phosphorus are implanted into the polycrystalline silicon film through the gate insulating film 3 by an ion implantation method.
The source / drain 5 of the channel transistor is formed (FIG. 2B). Thereafter, as an interlayer insulating film, a silicon dioxide film 6 is formed to a thickness of about 350 nm, and a contact hole 7 for wiring connection and a wiring electrode 8 are formed by etching in a predetermined pattern (FIG. 2).
(C)).

[0005]

However, in the conventional manufacturing method, the MIS is required for miniaturization and high density.
When the size of the type transistor is reduced, the current value of the transistor for operating the configured semiconductor circuit normally cannot be increased, and the semiconductor circuit does not operate normally. I was

According to the present invention, in order to solve the above-mentioned conventional problems, a semiconductor layer in a portion opposed to a gate electrode is formed in two upper and lower layers.
Even if the planar dimension of the IS type transistor is reduced, the current characteristics flowing through the transistor can be secured, and the area for forming the semiconductor circuit is reduced, so that a highly integrated TFT type liquid crystal display device and a method of manufacturing the same are provided. The purpose is to provide.

[0007]

In order to achieve the above object, a thin film transistor (TFT) type liquid crystal display device according to the present invention comprises a first insulating film formed on a surface of a first semiconductor layer and a gate electrode formed thereon. Forming a second insulating film so as to cover the gate electrode; opening a part of the first and second insulating films to form a second insulating film connected to a part of the first semiconductor layer;
And a field effect (MIS) semiconductor type transistor is formed.

Next, the thin film transistor (TFT) of the present invention
Forming a first semiconductor layer, forming a first insulating film on the surface of the first semiconductor layer, forming a gate electrode, and covering the gate electrode with a second insulating film. Forming a second semiconductor layer by opening a part of the first and second insulating films and connecting to the first semiconductor layer through the opening to form a field effect (MIS) semiconductor transistor It is characterized by having.

In the above method, it is preferable that the first semiconductor layer and the second semiconductor layer are formed of a polycrystalline silicon film.

In the above method, the first and the second
After the amorphous silicon film is formed as the semiconductor layer, it is preferable that the first and second amorphous semiconductor films are converted into polycrystalline silicon films by irradiation with an excimer laser.

According to the present invention, transistors can be efficiently formed in parallel above and below one gate electrode. Further, according to the present invention, even if the size of the MIS transistor is reduced for miniaturization and high density, the transistor is formed in parallel above and below one gate electrode, so that a semiconductor circuit Can operate with a large current value of the transistor.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a TFT type liquid crystal display device and a manufacturing method according to an embodiment of the present invention will be described with reference to the drawings.

FIGS. 1A to 1C are cross-sectional views schematically showing a method of manufacturing a TFT type liquid crystal display device according to an embodiment of the present invention. First, an amorphous silicon film 12 having a thickness of about 50 nm was formed as a first semiconductor layer on the surface of the glass substrate 1 by a plasma chemical vapor deposition (CVD) method. After that, a heat treatment was performed at about 450 ° C. for 1 hour in a vacuum exhaust to reduce the amount of hydrogen taken in the amorphous semiconductor layer 12. Next, the first amorphous silicon film 12 was turned into a polycrystalline silicon film by irradiating an excimer laser. Next, the above-mentioned polycrystalline silicon film was formed by etching into a predetermined pattern. Then, about 100 nm by a plasma CVD method.
Forming a silicon dioxide film having a thickness to form a first gate insulating film 14;
And Then, about 200 nm thick chromium (Cr)
A gate electrode wiring pattern 15 of the transistor was formed from the film. Thereafter, about 3 × 10 ¹⁵ / cm ² of phosphorus is implanted into the polycrystalline silicon film through the gate insulating film 14 by an ion implantation method, thereby forming the source / drain 13 of the N-channel transistor.
Was formed. Thereafter, a second gate insulating film 16 is formed to a thickness of about 100 nm by a plasma CVD method so as to cover the gate electrode wiring pattern 15, and the source / drain 13 of the N-channel transistor is formed by a photolithographic method.
The first gate insulating film 14 and the second gate insulating film 16 on the surface of the portion were opened (FIG. 1A).

Next, an amorphous silicon film 17 having a thickness of about 50 nm is formed as a second semiconductor layer.
After reducing the amount of hydrogen taken in 7, the second amorphous silicon film 17 was turned into a polycrystalline silicon film by irradiating an excimer laser. Thereafter, the second semiconductor layer 17 is formed by etching into a predetermined pattern, and the second semiconductor layer
Source / drain portions for forming channel transistors are opened by photolithography, and about 3 × 10 ¹⁵ phosphorus / cm ² is added to the second semiconductor layer 17 by ion implantation.
By implanting, the source / drain 18 of the N-channel transistor was formed (FIG. 1B).

Thereafter, a silicon dioxide film 19 having a thickness of about 350 nm was formed as an interlayer insulating film, and a contact hole 20 for wiring connection and a wiring electrode 21 were formed by etching in a predetermined pattern (FIG. 1C). .

As shown in FIG. 1C, the gate electrode 15
Are formed in the upper and lower two layers of the first semiconductor layer 12 and the second semiconductor layer 17 so as to reduce the planar dimension of the MIS transistor for miniaturization and higher density. Even if the size is reduced, the characteristics of the current flowing through the transistor can be secured, and a highly integrated TFT liquid crystal display device can be realized by reducing the area of the semiconductor circuit. More specifically, when the current value is the same as the conventional one, the size can be reduced to about 1/2.

In the embodiment of the present invention, the first and second semiconductor layers are formed by forming an amorphous silicon film by plasma CVD and then polycrystallized by an excimer laser or the like. However, the present invention is not limited to this. Instead, the effect is the same even if the polycrystalline silicon film is directly formed, and the same applies to the case where the film is formed of a plurality of semiconductor layers of three or more layers instead of two layers. The material of the gate wiring is a Cr film. However, the material is not limited to this. For example, a refractory metal film that is not affected by the process formation temperature of the second and subsequent layers, for example, tungsten (W), molybdenum (Mo) ), Tantalum (Ta) or a silicide or alloy thereof has the same effect. Also,
Although the transistor to be formed is an N-channel transistor, the present invention is not limited to this. The same applies to a P-channel transistor, and the amount of implanted impurities such as boron and phosphorus and the amount of implantation are also limited. is not.

[0018]

As described above, according to the present invention, by forming the semiconductor layer of the portion opposite to the gate electrode into two upper and lower layers by the above-described structure, the planarity of the MIS transistor is reduced for miniaturization and high density. Even if you reduce the typical dimensions,
The current characteristics flowing through the transistor can be secured,
By reducing the area of the semiconductor circuit,
A highly integrated TFT liquid crystal display device can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a method of manufacturing a TFT type liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is an explanatory view of a method for manufacturing a conventional TFT type liquid crystal display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Glass substrate, 2 Polycrystalline silicon film 3 Gate insulating film 12 1st semiconductor layer 14 1st gate insulating film 4, 15 Gate wiring pattern 16 2nd gate insulating film 17 2nd semiconductor layer 5, 13, 18 Source / drain of N-channel transistor 6,19 Silicon dioxide film 7,20 Contact hole 8,21 Wiring electrode

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H092 JA25 JA28 JA29 JA34 KA04 MA07 MA08 MA30 MA37 NA21 5C094 AA13 AA15 AA25 AA43 AA53 BA03 BA43 CA19 DA09 DA13 DB01 DB04 EA04 FA02 FB12 FB14 FB15 GB10 5F110 AA04 BB04 EE05 FF02 FF30 GG02 GG13 GG25 GG30 GG45 HJ01 HJ04 HJ13 NN04 NN23 PP03 PP35

Claims (4)

[Claims] A first insulating film formed on a surface of the first semiconductor layer and a gate electrode formed thereon; a second insulating film formed so as to cover the gate electrode; A thin film transistor characterized in that a field effect (MIS) semiconductor transistor is formed by forming an opening in a part of the insulating film and forming a second semiconductor layer connected to a part of the first semiconductor layer (TFT) type liquid crystal display device. 2. A first insulating layer is formed, a first insulating film is formed on a surface of the first semiconductor layer, a gate electrode is formed, and a second insulating film is formed to cover the gate electrode. Forming a second semiconductor layer by opening a part of the first and second insulating films and connecting to the first semiconductor layer through the opening to form a field effect (MIS) semiconductor transistor A method for manufacturing a thin film transistor (TFT), comprising: 3. The method according to claim 2, wherein the first semiconductor layer and the second semiconductor layer are formed of a polycrystalline silicon film. 4. An amorphous silicon film is formed as the first and second semiconductor layers, and the first and second amorphous semiconductor films are converted into a polycrystalline silicon film by excimer laser irradiation. Item 3. The production method according to Item 2.