JPH0486891A - El light emission device - Google Patents

Abstract

PURPOSE:To prevent light from being made incident on an offset part from the side of a glass substrate and to prevent a semiconductor layer from deteriorating by providing a light-shielding insulating film on the glass substrate side of a switching element. CONSTITUTION:The offset area is provided to a gate electrode 2 so as to increase the dielectric strength of the switching element Q2 and the light- shielding gate insulating film 31 is formed on the electrode 2. The insulating film 31 is formed of a material which cuts off light and has heat resistance, e.g. inorganic film of a-SixC1-x (x<=0.5), PrMnO4, etc., to prevent light from being made incident on a semiconductor layer 4 from the side of the glass substrate 1 and also preclude deterioration and damage during manufacture processes of respective film stuck on the insulating film 31.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an EL light emitting device used in an active matrix drive type ELL display device, and particularly to an EL light emitting device that has high reliability by providing a light shielding insulating film. The present invention relates to an EL light emitting device.

(Prior Art) In recent years, research and development of ELL display devices using EL (electroluminescence) light emitting elements has become active.

Among the above-mentioned ELL display devices, there is an active matrix drive type in which each pixel includes an EL light emitting element, a thin film transistor (TPT) for driving the EL element, a capacitor, etc. Active matrix drive type EL
FIG. 3 shows an equivalent circuit of an EL light emitting device for one bit of an example of an EL display device.

This EL light emitting device includes a first switching element Q;
a storage capacitor Cs having one terminal connected to the source terminal side of the switching element Q, and a storage capacitor Cs having a gate terminal connected to the source terminal of the first switching element Q1 and having a source terminal connected to the other side of the storage capacitor Cs. a second switching element Q2 connected to the terminal of the second switching element Q2; and an EL light emitting element, one terminal of which is connected to the drain terminal of the second switching element Q, and the other terminal of which is connected to the EL drive power supply Va. It consists of the top of element C.

The first switching element Q is turned on in response to the switching signal 5CAN applied to the gate terminal, and by turning on and off the first switching element Q, the storage capacitor Cs is turned on in response to the light emission signal DATA. It is now ready to write data. That is, the second switching element Q2 supplies the light emission signal D to the storage capacitor Cs.
When ATA (H) is written, the voltage is applied to the gate terminal to turn on, and the EL drive power supply Va causes the EL light emitting element CEL to emit light. Further, when the light emission signal DATA is (L), the charge accumulated in the storage capacitor Cs is discharged.

(Problem to be Solved by the Invention) According to the EL light emitting device as described above, when the second switching element Q2 is off, the EL drive power Va is applied between the drain and source of the second switching element Q2. Therefore, a high withstand voltage and low current characteristics that are approximately twice that of the EL drive power supply Va are required, and the semiconductor layer of the switching element that satisfies these specifications is limited to a limited number of semiconductor layers such as cadmium selenium (CdSe) and polysilicon (polys i ). material was used.

However, cadmium selenium (CdSe) has a problem in that the drain voltage-drain current characteristics are unstable due to aging, making it difficult to maintain constant brightness of the EL light emitting element CEL. In addition, polysilicon (
When depositing polys i ), it is necessary to set the process temperature high, so it is difficult to integrate the EL light emitting element CEL and the switching element Q on the same substrate to form a large area denomination (chair). There was a problem that it was not suitable.

Therefore, in order to eliminate the above-mentioned drawbacks of cadmium selenium (CdSe) and polysilicon (polys i ), switching elements using amorphous silicon (aSi) for the semiconductor layer have been proposed.

As shown in FIG. 4, this switching element Q2 has a gate electrode 2.0 on a glass substrate 1. Gate insulating film 3. Semiconductor layer made of amorphous silicon (a-3i) 4. Channel protection layer5. In addition to sequentially forming the source electrode 6 and the drain electrode 7, the gate electrode 2 is
is offset toward the source electrode 6 side.

However, according to the above structure, an offset region A is generated in the channel portion of the semiconductor layer 4.

Since the glass substrate 1 side is the display side, and the gate insulating film 3 is formed of a transparent material such as SiNx, light enters the channel portion of the semiconductor layer 4 from the offset region A.

As a result, the level density in the semiconductor layer 4 increases, the probability of trapping increases, and changes over time such as a decrease in on-current occur, causing the switching element Q to deteriorate.

There was a problem that it deteriorated the characteristics of.

Further, if the offset region A portion is always irradiated with light, this portion becomes in a state similar to an on state, which hinders the ability to achieve a high breakdown voltage.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a structure of an EL light emitting device that is used in an active matrix drive type EL display device and has high reliability.

(Means for Solving the Problems) In order to solve the problems of the conventional example, the EL light emitting device of the present invention forms an EL light emitting element and a switching element connected to the EL light emitting element on a glass substrate, The switching element is characterized in that it has an offset portion and a light-shielding insulating film is provided on the glass substrate side of the switching element.

(Function) According to the present invention, since the light-shielding insulating film is provided on the glass substrate side of the switching element, light is prevented from entering the offset portion of the switching element from the glass substrate side, and deterioration of the semiconductor layer of the switching element is prevented. prevent.

(Example) An example of the present invention will be described with reference to FIG.

FIG. 1 is an explanatory cross-sectional view of an EL light emitting device according to an embodiment of the present invention. The EL light emitting device includes an EL light emitting element CEL formed on a glass substrate 1 and a switching element Q2, which is also formed on the glass substrate 1 and operates as a switch for supplying a driving voltage to the EL light emitting element CEL. It is configured.

The EL light emitting element CEL includes a transparent electrode 21. made of a transparent conductive film (ITO). First insulating layer 2 made of Si, N,
2. Luminescent layer 23 made of ZnS:Mn. A second insulating layer 24 made of Si, N. It is constructed by sequentially laminating metal electrodes 25 made of aluminum (AI).

The switching element Q2 has a gate electrode 2. made of chromium (Cr). Light-shielding gate insulating film 31. Semiconductor layer made of amorphous silicon (a-3i) 4. A channel protection layer 5 made of SiNx is sequentially laminated, and ohmic contact layers 11 and 12 made of n''a-3i and chromium (Cr
), a source electrode 6 and a drain electrode 7 made of aluminum are successively formed to form a thin film transistor (TPT).

Further, the gate electrode 2 is provided with an offset region on the drain electrode 7 side in order to increase the breakdown voltage of the switching element Q2. The metal electrode 25 and the drain electrode 7 are connected by a wiring 30 made of aluminum.

The light-shielding gate insulating film 31 is made of a material that blocks light and has heat resistance, for example, a-3i xc+-x (x≦0.5
), prMno, etc. Alternatively, it may be formed of an organic film such as black polyimide.

The light-shielding gate insulating film 31 is formed from a light-shielding material as follows.
This is to prevent light from entering the semiconductor layer 4 from the glass substrate 1 side. Furthermore, the reason why the light-shielding gate insulating film 31 is formed of a heat-resistant material is to prevent deterioration and damage during the manufacturing process of the six films deposited on the light-shielding gate insulating film 31. .

Next, a manufacturing process of the above-mentioned EL light emitting device will be explained.

A transparent conductive film (ITO) is deposited on the glass substrate 1 to form a transparent electrode 21 .

Next, Si, N, and ZnS:Mn were sputtered using E.
A first insulating layer 221, a light emitting layer 23, and a second insulating layer 24 are formed by depositing Si and N by B evaporation and sputtering, thereby forming an EL light emitting element CEL.

Next, a glass substrate 1 corresponding to the EL light emitting element CEL is
A chromium (Cr) film is deposited on the upper position and patterned by photolithography to form the gate electrode 2.

By decomposing a mixed gas of CH and SiH by the PCVD method, a-5i xcl-x (x≦0,5) is deposited to form a light-shielding gate insulating film 31. 3i to form a semiconductor layer 4, and further SiNx
A channel protective layer 5 is formed by depositing and patterning.

Next, n''a-3i and chromium (Cr) are deposited and patterned using the same mask to form an ohmic contact layer 11.12 and a barrier metal layer 13.14.

Finally, an aluminum (AI) film is deposited and patterned on the entire surface, and the second insulating layer 2 of the EL light emitting element CEL is formed.
A metal electrode 25 is provided on the barrier metal layer 13.14, and a source electrode 6.14 is provided on the barrier metal layer 13.14. A wiring 30 connecting the drain electrode 7 and the metal electrode 25 to the drain electrode 7 is formed.

FIG. 2 is a cross-sectional explanatory diagram showing another embodiment of the EL light emitting device.

In this embodiment, the gate insulating film 3 is a-3ixC+-x
The transparent gate insulating film 32 is made of 5iNX, a material conventionally used as a gate insulating film member. Since the other configurations are the same as those in FIG. 1, the same reference numerals are given and explanations are omitted.

The gate insulating film 3 having the above-mentioned two-layer structure is made of C.
By decomposition of a mixed gas of H, and SiH, a-3i
The light-shielding gate insulating film 31 is formed by depositing xC+-x (x≦0.5), and the gas is switched on the way without breaking the vacuum, and the light-shielding gate insulating film 31 is formed with a mixed gas of SH and NH. A transparent gate insulating film 32 made of SiNx is formed on the film 31, and then a semiconductor layer 4 is formed.

According to this embodiment, since the interface between the gate insulating film 3 and the semiconductor layer 4 is SiNx/a-3i, it is stable, and the characteristics of the thin film transistor TPT can be stabilized.

(Effects of the Invention) According to the present invention, since the light-shielding insulating film is provided on the glass substrate side of the switching element, light is prevented from entering the offset portion of the switching element from the glass substrate side, and the semiconductor layer of the switching element It is possible to prevent deterioration of the EL light emitting device and improve the reliability of an EL light emitting device using a high breakdown voltage switching element having an offset structure.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional explanatory diagram of an EL light-emitting device according to an embodiment of the present invention, FIG. 2 is a cross-sectional explanatory diagram showing another embodiment of the EL light-emitting device, and FIG. 3 is an EL light-emitting device using an active matrix drive method.
FIG. 4, which is an equivalent circuit diagram for one bit of a display device, is a cross-sectional explanatory diagram of a switching element having a conventional offset structure. 6... Source electrode 7... Drain electrode 21... Transparent electrode 22... First insulating layer 23... Light emitting layer 24... ...Second insulating layer 25...Metal electrode 3]...Light-shielding gate insulating film 32...Transparent gate insulating film Q,...No. 1 switching element Q2...
...Second switching element CEL...EL light emitting element 1...Glass substrate 2...Gate electrode 3...Gate insulating film 4... ...Semiconductor layer Figure 1 Figure 3 Figure 2

Claims (1)

[Claims] An EL light emitting element and a switching element connected to the EL light emitting element are formed on a glass substrate, the switching element has an offset portion, and a light shielding insulating film is provided on the glass substrate side of the switching element. An EL light emitting device.