JP2904984B2 - Display device manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thin film transistor (T
The present invention relates to a method for manufacturing a driver monolithic display device in which a display unit having FT) and a driver circuit for driving the display unit are incorporated on the same substrate.

[0002]

2. Description of the Related Art Conventionally, a driver monolithic type TFT substrate has been used for a display device. FIG. 6 shows an example of a driver monolithic TFT substrate. On the driver monolithic TFT substrate 20, the pixel electrode 2
1 and a display unit 23 having a TFT 22 and the like; a driver circuit 24a for driving the display unit 23;
24b are formed. Driving driver circuit 24
a and 24b have TFTs (not shown) for driving the display unit 23. Normally, driver circuit 2 for driving
The TFTs in the display unit 23 include TFTs 4a and 24b.
The same configuration as that described above is used.

The TFTs of the display section 23 and the TFTs of the driver circuits 24a and 24b have, for example, the configuration shown in FIG. Semiconductor layers 32a, 32b, 3 such as a polycrystalline silicon layer formed on an insulating substrate 31;
2c, channel layers 39a, 39b, 39c and high impurity concentration regions (N ⁺ regions or P ⁺ regions) 40a, 40
b and 40c are formed. Channel layer 39a, 3
Gate electrodes 35a, 35b, and 35c are provided above the gate electrodes 9b and 39c with the gate insulating film 34 interposed therebetween. Gate electrodes 35a, 35b, 35c and gate insulating film 34
An interlayer insulating film 36 is formed thereon. Contact hole 3 penetrating through gate insulating film 34 and interlayer insulating film 36
7a, 37b and 37c are high-concentration impurity regions 40, respectively.
a, 40b, and 40c. High concentration impurity regions 40a, 40b, 40c and electrodes 38a, 38b, 3
8c are the contact holes 37a, 37b, 3
7c are electrically connected.

The TFTs in the driving driver circuits 24a and 24b are required to have high carrier mobility in the channel layers 39a and 39b in order to cope with high-speed display. Channel layer 3 with high carrier mobility
To obtain 9a and 39b, the channel layers 39a and 39b
It is necessary to increase the crystal grain size of b and reduce the electrical resistance due to the grain boundaries. For example, the semiconductor layers 32a, 32
When b is a polycrystalline silicon layer, a crystal grain size exceeding 1 μm is required.

Further, driving driver circuits 24a, 24
Since the TFTs in b require current driving capability, a relatively large size TFT is used.
In order to improve the aperture ratio, a smaller size TFT is required.

[0006]

SUMMARY OF THE INVENTION A driver circuit for driving 2
When the crystal grain size of the channel layers 39a and 39b of the TFTs 4a and 24b is about 1 μm, the crystal grain size of the channel layer 39c of the TFT of the display unit 23 is also about 1 μm, which is about the same as the size of the channel layer 39c. Therefore, the characteristics of the TFT having a small size vary. Therefore, a TFT having the same crystal grain size as the channel layer is not suitable for use as a TFT in a display portion.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a display device in which carrier mobility in a channel layer of a driving driver circuit is high and variation in TFT characteristics of a display portion is small . It is to provide a manufacturing method .

[0008]

SUMMARY OF THE INVENTION Manufacturing of the display device of the present invention
The method includes a display unit and to form a driver circuit for the channel layer to drive the display unit have a second thin film transistor made of polycrystalline silicon on the same substrate having a first thin film transistor in which a channel layer is made of polycrystalline silicon Or
First, the polycrystalline silicon crystal grains of the first thin film transistor
The diameter of the polycrystalline silicon grains of the second thin film transistor
A manufacturing method of a display device smaller than the diameter, the
A channel layer of the first thin film transistor, the SiH ₄ raw material
Polycrystalline silicon on the substrate by low pressure CVD as gas
Depositing and forming a second thin film transistor;
Pressure channel using Si ₂ H ₆ as a source gas.
After depositing an amorphous silicon layer on the substrate by D method
Then, the amorphous silicon layer is polycrystalline silicon
It encompasses and forming a layer, Ru above object is achieved by the.

Next, the present invention will be described based on embodiments.
An example in which the semiconductor layer is made of polycrystalline silicon will be described with reference to FIGS.

First, 100 n of silicon is deposited on an insulating substrate 1 made of quartz or glass by a low pressure CVD method.
m. Deposition conditions, as a deposition gas, Si ₂ H
₆ (flow rate 100 sccm) and N ₂ (flow rate 400 sccm)
Pressure of 50 Pa and deposition temperature of 4
70 ° C. In this example, the deposition temperature was set at 470 ° C., so that the deposited silicon layer was an amorphous silicon layer.

Next, an N layer is applied to the amorphous silicon layer.
_The amorphous silicon layer was polycrystallized by performing heat treatment at 600 ° C. for 24 hours in _two atmospheres to obtain a polycrystalline silicon layer.

In the above-mentioned polycrystalline silicon layer, only the portions (2a, 2b) which are part of the TFTs of the driver circuit for driving are left, and the other portions of the polycrystalline silicon layer are removed by etching by a usual method ( (Fig. 1).

[0013] Next, the entire substrate surface by CVD after forming the insulating layer 3 to 100nm deposited S _i O _2, by low pressure CVD method, on the entire substrate surface, 100nm deposited polycrystalline silicon (Fig. 2). The deposition conditions were SiH ₄ (flow rate 100 sccm) and N
Using a mixed gas of ₂ (flow rate 400 sccm), the pressure was set to 50 Pa, and the deposition temperature was set to 620 ° C. (FIG. 2).

Next, a portion 2c which is a part of the TFT of the display portion
The polycrystalline silicon layer was removed by etching using a conventional method, leaving only the polycrystalline silicon layer (FIG. 3). At this time, the polycrystalline silicon layer 2a, 2b of the drive driver circuit section, because it is protected by the insulating layer 3 of S _i O _2, not etched.

The crystal grain size of the polycrystalline silicon layers 2a and 2b of the TFT in the driving driver circuit portion exceeds 1 μm, whereas the crystal grain size of the polycrystalline silicon layer 2c of the TFT in the display portion is 100 nm. The following is small enough. This is because the polycrystalline silicon 2c is deposited at a relatively high temperature using SiH ₄ as a source gas, while the polycrystalline silicon 2a, 2b is deposited at a relatively high temperature using Si ₂ H ₆ as a source gas. This is because it was obtained by:

Next, the insulating layer 3 on the polycrystalline silicon layers 2a and 2b of the driving driver circuit portion was removed (FIG. 4).
Hereinafter, a display device was manufactured according to a usual method. That is,
First, S _i O ₂ is deposited by after forming a gate insulating film 4, a polycrystalline silicon layer 2a, 2b, the gate electrode 5 by sputtering on the gate insulating film 4 on 2c across the substrate
a, 5b and 5c were formed. Then, an interlayer insulating film 6 is deposited a S _i O ₂ to the substrate across the. Contact holes 7a, 7b,
7c, the contact holes 7a, 7b,
Higher concentration (10 to 10 atom / cm ² ) of impurities (BF ₃ , PH _3, etc.) in the polycrystalline silicon layers 2a, 2b, 2c than 7c
Was implanted to form N ⁺ -type or P ⁺ -type high-concentration impurity regions 10a, 10b, and 10c. Finally, electrodes 8a, 8b, 8c are formed in the contact holes 7a, 7b, 7c by sputtering. With the above method, a display device as shown in FIG. 5 can be manufactured.

In the above-described manufacturing process, the amorphous silicon layer is formed to a thickness of 100 nm by a low pressure CVD method under the same conditions as those for depositing the polycrystalline silicon layer 2c of the TFT in the display section.
The polycrystalline silicon after depositing on an insulating substrate 1, S _i
The ions are accelerated at an energy of 60 keV and a dose of 1 × 1.
It can also be formed by injecting this polycrystalline silicon layer under the condition of 0 ¹⁵ cm ^-2 and amorphizing the polycrystalline silicon layer.

First, after forming the polycrystalline silicon layer 2c of the TFT of the display portion, the TF of the driver circuit for driving is formed.
T polycrystalline silicon layers 2a and 2b may be formed.

[0019]

As is apparent from the above description, according to the method of manufacturing a display device of the present invention, the channel layer of the thin film transistor of the driving driver circuit is formed using Si ₂ H ₆ as a source gas.
An amorphous silicon layer on a substrate by low pressure CVD
Since the deposition is performed, the amorphous silicon layer can be formed into a uniform film.
Then, the amorphous silicon layer, which has been made into a homogeneous film, is subjected to heat treatment.
Since a polycrystalline silicon layer is used, the polycrystalline silicon
The crystal grain size of the recon layer can be increased, and the surface
Thin film transistors in the driver circuit for driving
Low threshold voltage, high carrier mobility,
Low leakage current and high speed display
Display becomes possible. In addition, the thin film transistor of the display section
The channel layer is formed by a low pressure CVD method using SiH ₄ as a source gas.
Deposits and forms a polycrystalline silicon layer on the substrate
The channel of the thin film transistor of the driver circuit for driving.
Grain size of the formed polycrystalline silicon layer
Because it can be made smaller,
Variation can be reduced, and good image quality can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a manufacturing process of a display device of the present invention.

FIG. 2 is a cross-sectional view illustrating a manufacturing process of the display device of the present invention.

FIG. 3 is a sectional view illustrating a manufacturing process of the display device of the present invention.

FIG. 4 is a cross-sectional view illustrating a manufacturing process of the display device of the present invention.

FIG. 5 is a sectional view showing an example of a display device manufactured according to the present invention.

FIG. 6 is a configuration diagram illustrating an example of a driver monolithic TFT substrate.

FIG. 7 is a cross-sectional view illustrating an example of a conventional display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating substrate 2a, 2b, 2c Polycrystalline silicon layer 3 Insulating layer 4 Gate insulating film 5a, 5b, 5c Gate electrode 6 Interlayer insulating film 7a, 7b, 7c Contact hole 8a, 8b, 8c Electrode 9a, 9b, 9c Channel Layer 10a, 10b, 10c High concentration impurity region 20 Driver monolithic TFT substrate 21 Pixel electrode 22 TFT 23 Display unit 24 Driver circuit 31 Insulating substrate 32a, 32b, 32c Semiconductor layer 34 Gate insulating film 35a, 35b, 35c Gate electrode 36 Interlayer insulating film 37a, 37b, 37c Contact hole 38a, 38b, 38c Electrode 39a, 39b, 39c Channel layer 40a, 40b, 40c High concentration impurity region

Claims (1)

(57) [Claims] And 1. A display unit having a first thin film transistor in which a channel layer is made of polycrystalline silicon, a driver circuit for the channel layer to drive the organic and the table <br/> radical 113 a second thin film transistor of polycrystalline silicon formed on the same substrate
And the polycrystalline silicon of the first thin film transistor
The crystal grain size of the polycrystalline silicon of the second thin film transistor
A method for manufacturing a display device which is formed to be smaller than a crystal grain size , wherein a channel layer of the first thin film transistor is formed from SiH ₄ .
Polycrystalline silicon on the substrate by a low pressure CVD method as a source gas.
Depositing and forming a capacitor layer, and forming a channel layer of the second thin film transistor from Si ₂ H ₆ .
Amorphous silicon on the substrate by low pressure CVD as a source gas.
After depositing a silicon layer, the amorphous silicon layer is subjected to a heat treatment.
Method of manufacturing includes the display device and forming a more polycrystalline silicon layers.