JPH0517170B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a zinc sulfide-based thin film,
In particular, it relates to a method for producing a homogeneous, high-quality zinc sulfide-based thin film that does not contain microparticles or pinholes in the thin film. Conventionally, zinc sulfide-based thin films have been formed by electron beam evaporation of zinc sulfide-based sintered bodies.
The zinc sulfide-based sintered body used in this case is made by molding zinc sulfide powder or zinc sulfide powder containing active substances such as Mn, Cu, and TbF ₃ at a pressure of, for example, 400 kg/cm ² and then blowing inert gas or hydrogen sulfide. It was formed by firing at a temperature of 1000° C. to 1200° C. for 1 to 3 hours in an inert gas containing. When a zinc sulfide-based sintered body formed in this way is irradiated with an electron beam and heated to evaporate to form a zinc sulfide-based thin film, microparticles and pinholes with a particle size of 1 to 20 microns are generated in the thin film. There were flaws. Furthermore, when such a thin film is applied as an EL thin film, microparticles and pinholes cause dielectric breakdown, making it impossible to form a stable EL element. The reason for the formation of microparticles and pinholes in the thin film is that the zinc sulfide sintered body produced by the conventional method has a density of about 60 to 75% of the theoretical density, and the crystal grain size that makes up the sintered body Also, zinc sulfide-based sintered bodies sublimate and evaporate without melting, so when the zinc sulfide sintered body is irradiated with an electron beam and evaporated, it becomes electrically charged, and the microscopic particles that were present in the sintered body are charged. This is thought to be because particles and microparticles made of crystal grains that have become smaller due to sublimation are scattered due to electrostatic repulsion and adhere to the substrate surface. The present invention is based on the above-mentioned conventional technology, and uses powder containing zinc sulfide as a main component, Li, Na, K, Rb, Cs, Ba,
A zinc sulfide-based sintered body formed by adding one or more types of chlorides, hydroxides, and nitrates of Sr, Ca, and Mg and heat-treating it in an inert gas or sulfide atmosphere is irradiated with an electron beam, It uses heating and evaporation, so-called electron beam evaporation, to form a high-quality, homogeneous zinc sulfide-based thin film with almost no microparticles or pinholes in the thin film. The zinc sulfide sintered body created by this method contains Li, Na, K, Rb, Cs, Ba, Sr, Ca, Mg
one or more of the following acts as a flux for sintering [described in J.Amer.Cer.Soc, page 65(2)C-18],
Due to the high density and large particle size, when irradiated with an electron beam, sublimation occurs uniformly from the surface of the sintered body, which is thought to provide the above characteristics. In addition, as metals to be added, Li, Na, K, Rb, and Cs are effective, and the addition amount is 0.1 to 0.1 to
2 atomic % was appropriate. In other words, if it is less than 0.1%, the effect is weak, and if it is more than 2%, it has the disadvantage of reacting with the boat during firing. Further, as other metals, Ca, Mg, Sr, and Ba were effective, and the appropriate amount to be added was 0.02 to 2 atomic percent relative to zinc. That is, below 0.02 atomic %, the effect is weak, and above 2 atomic %, there is a drawback that it reacts with the boat during firing. Li, Na, K, Rb, Cs,
Ba, Sr, Ca, and Mg could be easily added homogeneously by wet mixing using water-soluble compounds such as chlorides, hydroxides, or nitrates. In addition, Mn,
Cu, Ag, Al, Tb, Dy, Er, Pr, Sm, Ho,
Even when it contains Tm or at least one of these halides, Li, Na,
Addition of one or more of K, Rb, Cs, Ba, Sr, Ca, and Mg is effective. This will be explained below using examples. Commercially available zinc sulfide powder (particle size 0.1 to 1.5 microns) contains Li, Na, K,
After adding one or more compounds of Rb, Cs, Ba, Sr, Ca, Mg and mixing in a mortar, approximately 10% by weight
of water was added, further mixed, and then granulated. This powder was molded at a pressure of 400Kg/cm ² to a diameter of 15mm and a thickness of
A 10 mm cylindrical body is heated at a temperature of 1000 to 1200°C in a sulfuric atmosphere or an inert gas atmosphere for 1 hour.
The firing of the time was carried out. Table 1 shows the Li used,
Type and concentration of metal compounds of Na, K, Rb, Cs, Ba, Sr, Ca, Mg, firing atmosphere, firing temperature,
The firing time and the density (ratio to theoretical density) of the obtained zinc sulfide-based sintered body are shown. As can be seen from the table, the density of the obtained sintered body was 90% or more of the theoretical density. When a zinc sulfide-based thin film was formed using this sintered body by electron beam evaporation, the microparticles in the thin film and pins The number of holes was drastically reduced, and a high-quality, homogeneous zinc sulfide-based thin film could be formed. In addition, the EL light emitter layer 4 of the EL element as shown in the drawing
A zinc sulfide-based sintered body containing 0.03 at% barium chloride was deposited using an electron beam, and Mn was simultaneously deposited by resistance heating to form a zinc sulfide thin film containing 0.8 at% Mn, and the luminescence properties were measured. As a result, it was found that the EL element was stable, with very little dielectric breakdown.

【table】

[Table] As described above, according to the manufacturing method of the present invention, a high-quality zinc sulfide-based thin film with extremely few pinholes and minute deposits can be formed with good reproducibility. It can be widely applied as a phosphor thin film, which is being researched as a fluorescent screen for CRTs, or an EL thin film.

[Brief explanation of drawings]

The drawings are diagrams showing the structure of an EL element formed by a manufacturing method according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Glass substrate, 2...Transparent electrode, 3...Yttrium oxide thin film, 4...Manganese activated zinc sulfide thin film, 5...Yttrium oxide thin film, 6...Aluminum electrode.

Claims (1)

[Claims] 1 Main component is zinc sulfide, Li, Na, K, Rb,
A material containing one or more of chlorides, hydroxides, and nitrates of Cs, Ba, Sr, Ca, and Mg as an additive is heat-treated in an inert gas or sulfide atmosphere to form a zinc sulfide-based sintered body, and the sulfide irradiating the zinc-based sintered body with an electron beam to heat and evaporate the zinc sulfide-based sintered body,
A method for producing a zinc sulfide-based thin film, which comprises depositing a zinc sulfide-based thin film on a substrate. 2 The zinc sulfide-based sintered body contains Mu, Cu, Ag, Al,
The method for producing a zinc sulfide-based thin film according to claim 1, characterized in that it contains at least one of Tb, Dy, Er, Pr, Sm, Ho, and Tm. 3. Production of a zinc sulfide-based thin film according to claim 1, characterized in that the concentration of one or more additives of Li, Na, K, Rb, and Cs relative to zinc is 0.1 to 2 atomic %. Method. 4. The method for producing a zinc sulfide-based thin film according to claim 1, wherein the concentration of one or more additives of Ba, Sr, Ca, and Mg relative to zinc is 0.02 to 2 atomic %.