JP3060582B2 - Active matrix type fluorescent display tube and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film transistor control type fluorescent display panel, and more particularly to an active matrix type fluorescent display tube in which a phosphor layer is formed by an electrodeposition method.

[0002]

2. Description of the Related Art In recent years, in the field of display device technology, an active matrix drive system for integrating a switching element in each pixel and controlling and driving each pixel to improve display performance has been developed. , Fluorescent display tube (FIP), electrochromic display device (ECD), electroluminescent device (E
(LD). In the LCD, an active matrix drive type LCD (AM-LC) using a thin film transistor (TFT) having amorphous silicon (a-Si) as an active layer as a switching element.
D) is a stage of mass production and commercialization. In the field of fluorescent display tubes, an active matrix drive type FIP (AM-FIP) using a TFT has been announced [K. Sera et al., "Japan Display '89 Proceeding" (K, Sera atel, "Japan Dis").
play '89 Proceedings "), 70
0 (1989)].

In general, TFTs, MIMs (Metal-In)
As with other semiconductor devices, a passivation film is formed on the surface of a thin-film device such as a sul- lator-metal) diode in order to stabilize the characteristics and prevent the surface from being affected by the outside. Conventionally, the passivation technique is a surface treatment technique for protecting against contamination such as alkali ions. Alkali ion (Na
⁺ ) Is easily diffused into the inside when it adheres to the surface of the SiO ₂ film through various media, moves inside according to the electric field, increases the leakage current of the pn junction, changes the threshold voltage,
The effect on device characteristics, such as an increase in noise, is significant. By performing the passivation process, the contamination is absorbed or fixed, and the influence on the device can be removed. Although the above is for stabilizing the characteristics of the MOS structure device, the formation of a surface protective film after the formation of the metal wiring is also a passivation technique necessary for improving device reliability.
As a passivation treatment as such a surface protective film, a method of forming a glass layer of SiO ₂ or the like or an insulating layer of Si ₃ N ₄ or the like on the surface is general. Also,
Passivation technology has led to the application of thin film devices such as TFTs and MIM diodes to the field of display devices.
There is a need not only for improving device characteristics and protecting the surface, but also in another dimension.

[0004] In AM-FIP, a phosphor electrodeposition method is employed as a method for forming a fine matrix phosphor screen. In the phosphor electrodeposition method, a voltage is applied to an organic solvent in which phosphor particles are dispersed, in which a phosphor-coated surface and a counter electrode are immersed, and a voltage is applied to the counter electrode so that the coated surface has a negative potential. A layer is formed on a desired adherend surface.

As shown in FIG. 3, a P-type channel TFT (P
ch-TFT) 31 as a switching element
In the M-FIP, a negative potential is applied to the gate electrode 32 and the source electrode 33 with respect to the counter electrode 34, and the P-ch TF
By turning on T31, the phosphor is deposited on the drain electrode 35. At this time, the passivation film formed of SiO ₂ , Si ₃ N ₄ or the like formed on the device surface needs to have a performance as an insulating film for preventing the phosphor from being attached to the metal wiring.

[0006]

As mentioned above, usually,
When a passivation film made of a Si ₃ N ₄ film or a SiO ₂ film formed on a device surface is used as a mask when forming a phosphor screen by an electrodeposition method, insulation becomes insufficient.
There has been a problem that the phosphor particles adhere to the passivation film along the pattern of the metal wiring.
Removal of such unnecessary phosphor particles complicates the subsequent removal operation, and it is virtually impossible to remove particles deposited on wiring arranged in a narrow space in the matrix. This causes unnecessary light emission and deteriorates display quality.

[0007]

According to the present invention, there are provided switching elements arranged and formed in a matrix on a glass substrate inside a vacuum envelope, and an electrodeposition method is performed on one electrode of the switching element. In the active matrix type fluorescent display tube which emits light by impacting the phosphor layer formed by the method with an electron beam, the passivation film of the control element is composed of two layers of a silicon nitride layer and a fired film of photoresist.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG.
Is a forward staggered type polysilicon (Poly-type) used for an AM-FIP switching element according to an embodiment of the present invention.
(Si) It is sectional drawing of a TFT part. Glass substrate 11, 1
The space between 1a is evacuated. The cathode and the grid are arranged in this space, and the switching elements and the phosphors 17 are arranged and formed in a matrix on the inner surface of the glass substrate 11 together with the metal wiring 15. To form a switching element, first, a Poly-Si
A layer is formed, and ion implantation is performed on the Poly-Si layer. After the heat treatment, predetermined patterning is performed to form the source / drain layers 12. On top of this, intrinsic Poly-Si
The layer is formed by a low pressure vapor phase epitaxy (LP-CVD) method, and is patterned to form an active layer 13. A silicon oxide (SiO ₂ ) film serving as a gate insulating film 14 is further formed thereon by the LP-CVD method. To form a film. Next, a contact hole is opened and chromium (Cr) and aluminum (Al)
The layers are continuously formed by a vapor deposition method, and are patterned to form the metal wiring 15. On the surface of the device thus formed, a silicon nitride (Si ₃ N ₄ ) layer 16 is formed by a plasma-enhanced chemical vapor deposition (P-CVD) method, and a polycinnamic acid side β-vinyloxyethyl ester negative type is formed. Using a photoresist, patterning is performed by a lithography technique to expose only the phosphor-coated surface 17a. In a normal process, the resist is removed after the etching process. However, in the present invention, the resist is baked by heat treatment in the air at 240 ° C. for 30 minutes after the etching to completely remove the residual organic solvent component. By this heat treatment, the fired resist film 18 becomes insoluble in the electrodeposition method in which the phosphor is dispersed in the organic solvent. After that, the phosphor 17 is formed on the exposed metal wiring. Thus, the obtained Si ₃ N ₄
By using the passivation film as the two layers, the layer and the photoresist baked film, it is possible to completely insulate the metal wiring and the electrodeposition solution during electrodeposition, and the phosphor particles are coated on the passivation film on the metal wiring. Wearing can be prevented.

The other points, such as the adhesion of the glass substrates 11 and 11a and the arrangement and formation of the cathode and anode, are the same as those in the prior art, and therefore the description thereof is omitted.

FIG. 2 is a sectional view of an inverted staggered type Poly-Si TFT according to a second embodiment of the present invention. Other parts are not shown. To form this SiTFT, first, Cr is deposited on a glass substrate 21 and patterned to form a gate electrode 22. Next, after a SiO ₂ layer is formed as the gate insulating layer 23 by the LP-CVD method, a Poly-Si layer to be the active layer 24 is formed by the LP-CVD method. After patterning the Poly-Si layer in an island shape, ion implantation is performed to form source / drain regions 25. Subsequently, a Cr film is deposited and patterned to form the metal wiring 26, thereby completing the inverted staggered type Poly-Si TFT. On the surface of the device thus formed, a Si ₃ N ₄ layer 27 is formed by a P-CVD method, and is patterned by lithography using a cyclized rubber-azide negative photoresist, and a phosphor is deposited. Only the surface 28 is exposed. Subsequently, the resist is heat-treated in the air at 300 ° C. for 30 minutes to remove residual organic solvent components, thereby completing a resist fired film 29 which is insoluble in the electrodeposition method. In addition to the photoresists used in the first and second embodiments, it is also possible to use an oil-soluble photoresist such as a polyvinyl cinnamylidene acetate-based photoresist or a 0-naphthoquinonediazide-based photoresist. By using the thus obtained two layers of the Si ₃ N ₄ layer and the photoresist baked film as the passivation film, the metal wiring and the electrodeposition liquid are completely insulated during the electrodeposition as in the first embodiment. It is possible to prevent phosphor particles from being attached to the passivation film on the metal wiring.

[0011]

As described above, according to the present invention, the AM
During electrodeposition since the passivation film of the switching element is constituted by two layers of sintered film the Si ₃ N ₄ layer and the photoresist in -fip, it is possible to completely isolate the metal wiring and the electrodeposition solution, the metal wires This has an effect that phosphor particles can be prevented from adhering to the passivation film thereon. This makes it possible to provide an active matrix type fluorescent display tube with excellent display quality without unnecessary light emitting elements.

[Brief description of the drawings]

FIG. 1 shows a forward staggered type Poly-Si according to an embodiment of the present invention.
FIG. 4 is a cross-sectional view of a TFT.

FIG. 2 is an inverted staggered type Poly- according to a second embodiment of the present invention.
Sectional drawing of a SiTFT.

FIG. 3 is an explanatory diagram of a phosphor electrodeposition method when a P-ch TFT is used as a control element.

[Explanation of symbols]

11, 21 Glass substrate 12 Source / drain layer 13, 24 Active layer 14, 23 Gate insulating layer 15, 26 Metal wiring 16, 27 Si ₃ N ₄ layer 17a, 28 Phosphor-coated surface 18, 29 Resist baking film 22, 32 Gate electrode 25 Source / drain region 31 Pch-TFT 33 Source electrode 34 Counter electrode 35 Drain electrode

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-294328 (JP, A) JP-A-61-198531 (JP, A) JP-A-51-38864 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01J 31/15

Claims (4)

(57) [Claims] A switching element arranged and formed in a matrix on a glass substrate inside a vacuum envelope; and a phosphor layer formed by electrodeposition on one electrode of the switching element. In an active matrix type fluorescent display tube in which the phosphor is irradiated with an electron beam to emit light, a passivation film of the switching element is baked by removing an organic solvent component of a silicon nitride layer and a photoresist.
The active matrix type fluorescent display tube which is characterized by being composed of two layers meta insulating photoresist baked film. 2. A cyclized rubber-azide based photoresist is used as a photoresist.
The actip according to claim 1, wherein a moth-shaped photoresist is used.
Matrix type fluorescent display tube. 3. A switching element mounted on a glass substrate.
Arranging and forming in a liquefied form; and
After forming a silicon nitride layer covering the switching element,
Photoresist is deposited and patterned on silicon nitride layer
Using the patterned photoresist as a mask
After etching the silicon nitride layer, by heat treatment
The residual organic solvent component in the resist is removed to remove the resist.
Bake the silicon nitride on the switching element.
Passivator consisting of two layers:
Forming a switching film and contacting the switching element.
And exposed without being covered by the passivation film
A step of forming a phosphor layer on a metal wiring portion by an electrodeposition method;
Active matrix type fluorescence characterized by having
Display tube manufacturing method. 4. A cyclized rubber-azide based photoresist is used as a photoresist.
The actip according to claim 3, wherein a moth-shaped photoresist is used.
Manufacturing method of matrix type fluorescent display tube.