JPH0824069B2 - Method for manufacturing thin film EL element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The present invention is a thin film E using a ZnS thin film added with a rare earth as a base material.
In order to obtain an EL element with high reproducibility and high brightness in the L element, a two-source deposition method using ZnS as a light emitting base material source and a mixed target of rare earth fluoride and rare earth sulfide as a source for adding an emission center is used. It is possible to improve reproducibility and increase brightness.

[Industrial applications]

The present invention relates to a method for manufacturing a thin film EL (electroluminescence) element, and more specifically, to a method for manufacturing a thin film EL element capable of improving the luminous efficiency and brightness of the thin film EL element.

[Conventional technology]

A thin film EL element is a rare earth element such as terbium, samarium, thulium, praseodymium or the like that functions as a luminescence center, and a halogen element such as fluorine or chlorine. It is a light emitting element that emits light based on the luminescence phenomenon.

The present inventors have previously found that the composition ratio of the rare earth metal (trivalent) and the halogen element (monovalent) for forming the emission center is smaller than the stoichiometric ratio of 3: 1, and particularly preferably 1: 1. This is disclosed (Japanese Patent Application No. 60-217098).

As a method for forming an EL film having an emission center as described above, zinc sulfide, a halide of a rare earth element, and a sulfide of a rare earth element are independently or mixed and used as a source, or zinc sulfide and a rare earth element are mixed. It has been disclosed that it is effective to use a halide and sulfur independently or in a mixture as a source (Japanese Patent Application No. 60-282320).

[Problems to be solved by the invention]

By the above method, the reproducibility of the EL film was improved, and the luminous efficiency and brightness of the EL element were improved. However, it is desirable to further improve these for practical use of the thin film EL element.

[Means for solving problems]

In order to solve the above problems, the present invention includes the step of depositing zinc sulfide as a source of a mixture of a fluoride of rare earth metal and a sulfide of rare earth metal on one source to form an EL film. A method of manufacturing a characteristic thin film EL element is provided.

The molar ratio of fluorine (F) to sulfur (S) in the mixed source of rare earth metal fluoride and rare earth metal sulfide is 0.
It is within the range of 5 <F / S <1.5, but F / S = about 1.0 is most preferable. A mixed source of rare earth metal fluoride and rare earth metal sulfide is used as a rare earth metal hydrofluoride by reacting a mixture of fluoride and sulfide before being used as a source for EL film deposition. . With such a composition range and reaction product, the reproducibility and characteristics of the obtained EL film are significantly improved.

As the rare earth metal, terbium, samarium, thulium, praseodymium, etc. (a mixture thereof may be used) are preferable.

The EL film may be deposited by the above-mentioned two-source deposition method, such as sputtering method, plasma sputtering method, ion plating method,
A vapor deposition method or the like can be used. The addition mole ratio of the emission center material (MFS) to the emission base material (ZnS) is preferably about 0.5 to 6 mol%, and such an addition ratio is adjusted by adjusting the ratio of the deposition rates of the two sources. It is realized by co-deposition.

[Work]

The addition state of the emission center material in ZnS is rare earth (for example, T
The best condition is that b) replaces Zn and is bound to F located between the lattices. If Tb and F are then supplied using a dual source, then additional S is needed to neutralize these charges. Therefore, in order to realize such an added state by the two-source deposition method, when using ZnS source and TbF ₃ + Tb ₂ S ₃ source, it is best when the F / S in the TbF ₃ + Tb ₂ S ₃ source is 1. . To further improve reproducibility, Tb ₂ S ₃ + T
It would be desirable for the bF ₃ source to react to a new product, TbFS, rather than just a mixture of the respective powders.

〔Example〕

 Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a sputtering apparatus for carrying out the method of the present invention, and FIG. 2 shows a thin film EL element.

Referring to FIG. 2, a transparent electrode (IT
O) layer 2 and insulating film (Si ₃ N ₄ ) 3 are each formed by 2000Å sputtering. ZnS target, TbF ₃ on top of it
The ZnS: TbF film 4 is formed at 6000Å using a + Tb ₂ S ₃ target. After sputtering, heat treatment is performed at 600 ° C. for 1 hour, thereafter, a Si ₃ N ₄ film 5 is further formed to 2000 liters, and finally an Al electrode 6 is formed.

As shown in FIG. 1, the vacuum chamber 11 of the sputtering apparatus 10
A substrate 12 is set in the inside so that it can reciprocate between two targets, which will be described later, and a ZnS target 1 is used as a sputtering target.
3 and TbF ₃ + Tb ₂ S ₃ mixed target 14 were prepared separately.
In the figure, 15 and 16 are high frequency power supplies, and 17 is a heater. ZnS
The substrate temperature during sputtering is 250 ° C, the gas pressure of the sputtering gas (Ar) is 1 × 10 ^-2 torr, and the sputtering rate of ZnS is 80Å /
min, the sputter rate of TbF ₃ + Tb ₂ S ₃ was 1 Å / min.
The ratio of the sputter rate of ZnS and TbF ₃ + Tb ₂ S ₃ was monitored by a film thickness meter using a quartz oscillator, and the power applied to the target was adjusted so as to be constant during sputtering.

Here, TbF ₃ + Tb, which is the target for the emission center,
By changing the mixing ratio of TbF ₃ and Tb ₂ S ₃ in the ₂ S ₃ mixed target, the relationship with the brightness of the obtained thin film EL element (brightness at a voltage that drives at 1 KHz and exceeds the emission value voltage by 30 V) It was The results are shown in Fig. 3. When the F / S ratio in the mixed target is 1, the brightness is highest, and in the range of 0.5 <F / S <1.5, the brightness of 1/2 or more of the maximum brightness is obtained. It was Also simply TbF
₃ and Tb ₂ S ₃ powder mixed target and Tb
A comparison was made with the case where a target was used as a new product by hot pressing a mixture of F ₃ and Tb ₂ S ₃ at 850 ° C. and 5 atm. The X-ray diffraction patterns of the product obtained by hot pressing are, as shown in FIG. 4 (a), the X-ray diffraction pattern of TbF _{3 and} the X-ray diffraction pattern of Tb ₂ S _3. Different from (c), it shows that it is a new product TbFS. The brightness of the thin film EL device manufactured using these
As shown in the figure, when using a hot-pressed target, compared to using a simple mixture target,
A brightness of 1.5 times was achieved.

〔The invention's effect〕

According to the present invention, since TbF can be added to ZnS in a highly efficient state, it is effective in achieving high brightness and reproducibility.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a sputtering apparatus for carrying out the method of the present invention, FIG. 2 is a sectional view of a thin film EL element, and FIG. 3 is TbF ₃ + Tb ₂ S.
₃ Graph showing the brightness of thin film EL device with respect to F / S ratio in mixed target, Fig. 4 is X-ray diffraction pattern of various targets, and Fig. 5 is for using simple mixed target and hot press target Element characteristics (luminance)
It is a comparison graph figure of. 1 ... Glass substrate, 2 ... Transparent electrode layer, 3 ... Si ₃ N ₄ film, 4 ... Emitting layer (EL film), 5 ... Si ₃ N ₄ film, 6 ... Al electrode, 10 ... Sputtering equipment, 11 …… Chamber, 12 …… Substrate, 13 …… ZnS target, 14 …… TbF ₃ + Tb ₂ S ₃ mixed target.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor ▲ Yoshi ▼ Takuya 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Limited (72) Inventor, Seiei Sato, 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Incorporated (56) References JP 61-34890 (JP, A) JP 63-81791 (JP, A)

Claims (1)

[Claims] 1. One source is zinc sulfide, and the other source is a mixture of a rare earth metal fluoride and a rare earth metal sulfide, and the molar ratio of fluorine (F) to sulfur (S) is F / S.
Is within the range of 0.5 <F / S <1.5 and is a fluorinated sulfide formed by the reaction of a fluoride and a sulfide, including the step of depositing an electroluminescent film using a binary source Method for manufacturing thin film EL device.