KR20190130794A - Filament heater for thermal evaporator - Google Patents

Abstract

The present invention relates to a filament heater for a thermal evaporator. The filament heater for a thermal evaporator has a coil shape surrounding an outer surface of a container containing an organic material, wherein the coil shape has the variable number of turning a coil for each container portion.

Description

Filament Heater for Thermal Evaporator {FILAMENT HEATER FOR THERMAL EVAPORATOR}

The present invention relates to a filament heater for a thermal evaporator, and more particularly, to a filament type heater of a thermal evaporator used in the deposition of an organic material for manufacturing an organic electronic device represented by an organic light emitting diode.

The thermal evaporator is used to deposit thin films included in the organic light emitting diode display on a substrate.

Thermal evaporators generally comprise an evaporation source installed in a vacuum chamber. The substrate on which the organic material in the evaporation source is to be deposited is loaded into the vacuum chamber at a height spaced a predetermined distance from the evaporation source. The thermal evaporator applies power to the heater, heats the organic material of the evaporation source, vaporizes or sublimes it, and deposits it on the substrate. The evaporation source includes a crucible containing an organic material and a heater for heating the crucible.

Typically, the heater may be installed in a structure surrounding the cylindrical crucible. The heater may be made of filament of tantalum (Ta) (Tm: 2850 ° C tungsten (W) (Tm: 3387 ° C), which is a material having excellent thermal stability and efficiency.

The crucible heating method using a heater corresponds to an indirect heating method, in addition to the direct heating method for flowing electricity directly to the crucible or the electron beam heating method using an electron beam. Indirect heating using a heater is mainly used because the deposition control is stable.

Due to the nature of the organic material, when using a common heater is often sublimated (vaporized) from the side or bottom material as it is vaporized from the organic material adjacent to the heater. This causes various problems.

First, a problem of scattering of organic materials is generated. When the lower or side organic material is first sublimed (vaporized), the solid organic material is blown at the upper end. If organic materials are scattered, process time and costs are increased due to sample contamination, chamber contamination, and reduced utilization of organic materials.

In addition, crucible blockage occurs. This phenomenon occurs depending on the type of organic material and the shape of the crucible.In particular, in the case of an organic material having good reaction characteristics with the crucible, the upper part of the crucible is clogged because it is deposited on the upper part of the crucible where the temperature is relatively low during deposition. Cause. When crucible blockage occurs, deposition thin film uniformity and coverage are significantly reduced, resulting in poor deposition thin film reliability. This significantly increases process time and costs with reloading, clogging, crucible replacement, and the like.

The inventor of the present invention has completed the present invention after a long research and trial and error to solve these problems.

Embodiment of the present invention provides a filament heater for the thermal evaporator that can improve the process yield by improving the problems of the existing heater at a low cost.

On the other hand, other unspecified objects of the present invention will be further considered within the range that can be easily inferred from the following detailed description and effects.

The filament heater for the thermal evaporator according to an embodiment of the present invention has a coil shape surrounding the outer surface of the container containing the organic material, the coil shape may vary the number of coil turns for each container portion.

The container is divided into a continuous upper end, a stop and a lower end, and the number of coil turns surrounding the upper end may be greater than the number of coil turns surrounding the stop or the lower end.

The number of coil turns may increase from the lower end toward the upper end after the interruption part.

The upper end includes a first upper end having a larger diameter than the stop or the lower end, and a second upper end having the same diameter as the stop or the lower end, and the first upper end has a funnel shape of which diameter increases toward the uppermost part. The coil turns surrounding the first upper end and the second upper end may be more than the coil turns surrounding the stop or the lower end.

The coil pitch surrounding the upper end may be smaller than the coil pitch surrounding the stop or the lower end.

The coil pitch may be narrowed from the lower end toward the upper end after the interruption part.

The coil pitch surrounding the first upper end may be equivalent to the coil pitch surrounding the second upper end.

The present technology can provide a filament heater for the thermal evaporator that can improve the process yield by improving the problems of the existing heater at a low cost.

In addition, the present technology can provide a filament heater for a thermal evaporator that prevents material scattering and crucible blockage regardless of the type of material for organic material deposition.

In addition, the present technology can achieve a shorter overall process time by improving the reliability of the deposited thin film, simplifying the loading process through the application of a high capacity crucible independent of the material, and reducing the preheating time.

1 is a perspective view showing the overall shape of a filament heater for a thermal evaporator according to an embodiment of the present invention.
2 is a perspective view illustrating a filament heater for a thermal evaporator according to an embodiment of the present invention and a container mounted thereto.
3 is a cross-sectional view showing a filament heater for a thermal evaporator according to an embodiment of the present invention and a crucible mounted thereto.
4 is a cross-sectional view showing a filament heater for a thermal evaporator and a crucible mounted thereto according to another embodiment of the present invention.
5 is a view showing a comparative example of the use of the crucible to which the filament heater for the thermal evaporator according to an embodiment of the present invention is applied.
The accompanying drawings show that they are illustrated as a reference for understanding of the technical idea of the present invention, by which the scope of the present invention is not limited.

In the following, the most preferred embodiment of the present invention is described. In the drawings, the thickness and spacing are expressed for convenience of description and may be exaggerated compared to the actual physical thickness. In describing the present invention, well-known structures irrelevant to the gist of the present invention may be omitted. In adding reference numerals to the components of each drawing, it should be noted that the same components as much as possible, even if displayed on different drawings.

1 is a perspective view showing the overall shape of a filament heater 100 for a thermal evaporator according to an embodiment of the present invention.

2 is a perspective view showing the filament heater 100 and the container 10 mounted thereon for the thermal evaporator according to the embodiment of the present invention.

First, referring to FIG. 1, a filament-type heater 100 (hereinafter, referred to as a “heater” for convenience of description) is installed in the power supply unit P. Referring to FIG.

The heater 100 receives electric power from the power supply unit P and heats the container 10 (see FIG. 2) to be mounted therein.

The heater 100 may be formed of a material having excellent thermal stability and efficiency, for example, a filament made of tantalum or tungsten.

The container 10 may be formed of ceramic, which is an insulator material. The container 10 may be referred to as a crucible.

The heater 100 and the power supply unit P shown in FIG. 1 correspond to some components of the thermal evaporator. Although only some of the components of the thermal evaporator are illustrated in FIG. 1 for convenience of description, the present invention is not limited thereto. The thermal evaporator may include a vacuum chamber, a substrate placed in the vacuum chamber, and an organic thin film deposited on the substrate. The apparatus may further include a mask for forming a pattern on the substrate, a film thickness monitoring unit for monitoring the degree of film formation on the substrate, a film thickness control unit for receiving a signal from the film thickness monitoring unit and feeding back the film thickness information to the power supply. .

The heater 100 and the crucible 10 may be referred to as an evaporation source 1. The power supply unit P heats the crucible 10 included in the evaporation source 1 to generate evaporated particles from the evaporation source. To this end, the power supply may control the temperature of the evaporation source.

Referring to FIG. 2, the crucible 10 has a cylindrical structure.

According to the exemplary embodiment of the present invention, the crucible 10 may have an overhang structure in which a funnel-shaped opening portion O is formed at a top thereof in a cylindrical structure. On the whole, it can be seen that it includes a body portion (B), which generally maintains the same diameter, and a funnel-shaped opening portion (O) that increases in diameter toward the top.

An organic material (film forming material) S is accommodated in the crucible. As the organic material, a suitable material for the required film formation can be selected. The organic material may be a solid (usually a powder).

And, to enclose this crucible 10, the filament heater 100 has a cylindrical coil structure.

According to the exemplary embodiment of the present invention, the heater 100 may have a structure in which a funnel-shaped expansion portion E is provided at an upper end thereof in a cylindrical coil structure. On the whole, it can be seen that it includes a tunnel portion (T), the diameter of which is generally maintained consistently, and a funnel-shaped expansion portion (O) that increases in diameter toward the top.

The trunk portion B of the crucible is disposed in the tunnel portion T of the heater, and the opening portion O of the crucible is disposed in the extension portion E of the heater.

The extension portion E of the heater may serve not only to heat the crucible, but also to serve as a support for holding the crucible. The weight of the crucible can be supported by contact between the opening and the extension.

The funnel-shaped opening O of the crucible may be utilized for gripping. When the crucible is mounted inside the thermal evaporator or when the crucible is detached from the outside of the thermal evaporator, the crucible may correspond to a part of holding the crucible.

On the other hand, the crucible consumes the heat received as the evaporation source, the funnel-shaped opening (O) corresponds to a particularly large heat consumption. If there is a large portion of heat consumption, as described above, it may cause the problem of scattering of the organic material. As the bottom or side organic material of the crucible is first sublimed, the solid organic material at the top is blown. In addition, the organic material may adhere to the relatively low temperature during deposition, which may cause clogging of the upper end of the crucible.

Thus, the filament heater according to the embodiment of the present invention controls the temperature distribution by controlling the number of coil turns, that is, the number of coil turns. By controlling the filament heater to have a partially different structure, the heating portion and the heat distribution of the crucible are controlled. Hereinafter, the present invention will be described in more detail with reference to FIGS. 3 to 4.

3 is a cross-sectional view showing a filament heater 100 and a crucible 10 mounted thereto for the thermal evaporator according to an embodiment of the present invention. Corresponds to the cross-sectional view of FIG.

Referring to FIG. 3, the crucible 10 is mounted to the heater 100. The heater 100 is provided in a coil shape to surround the outer surface of the crucible 10.

The coil shape of the heater 100 has a variable coil turn for each crucible 10. That is, the crucible 10 may be divided into the upper part P1, the stop part P2, and the lower part P3 which are continuously connected, and the number of coil turns of the heater 100 is variable for each part of the crucible.

According to the exemplary embodiment of the present invention, the number of coil turns surrounding the upper end P1 may be greater than the number of coil turns surrounding the stop P2 or the lower end P3.

For example, in FIG. 3, the number of coil turns enclosing the upper end P1 is 11, the number of coil turns enclosing the stop P2 is 4, the number of coil turns encircling the lower end P3 is 5, and the upper coil turns 11 are interrupted. More than the sub coil turn 4 and the lower coil turns 5. That is, if the coil is wound four times at the stop portion or the coil is wound five times at the lower end, the coil is wound 11 times at the upper end to concentrate the heating element.

Therefore, the upper end portion P1 of the crucible is relatively higher in temperature than other portions P2 or P3 due to the concentration of the heating element, thereby preventing the above-mentioned problem of scattering of the organic material. This is because, as the temperature at the upper end is higher, the organic material at the upper end of the crucible can be sublimed (vaporized). The phenomenon of sublimation (vaporization) of the lower end portion or the middle portion of the organic material first than the upper end can be suppressed as much as possible.

In addition, since the upper end portion P1 of the crucible is relatively higher in temperature, the redeposition phenomenon of the sublimed material generated during the deposition process can be prevented, and thus the crucible top clogging phenomenon can be significantly reduced.

By controlling the temperature distribution by adjusting the number of coil turns, the problem of the existing heater can be solved very effectively with very little cost and effort.

3, the coil pitches d1, d2, and d3 for each crucible are shown together. This coil pitch may be a measure of whether the number of windings made about the same length, that is, the number of coil turns is large or small.

When the filament is coiled for the winding object having one winding axis, the coil pitch becomes narrower as the number of coil turns increases.

Therefore, the coil pitch d1 surrounding the upper end P1 appears smaller than the coil pitch d2 or d3 surrounding the interruption P2 or the lower end P3.

As such, the coil pitch is narrowly formed at the upper end of the crucible so that the heating element is concentrated at the upper end of the crucible and the temperature of the upper end of the crucible can be formed relatively higher than the other parts.

There may be various ways to increase the temperature of the upper part of the crucible, but the filament-type heater according to the embodiment of the present invention further means that only one turn of the filament of the same thickness is adjusted for each position. There is.

In addition, by increasing the number of coil turns directly under the funnel-shaped opening of the crucible, it is possible to more firmly secure a supporting structure for the role of the pedestal holding the crucible. This is because the larger the number of turns, the greater the number of coils in contact with the crucible and the stronger the supporting structure can be.

On the other hand, the upper portion (P1) has been described as an element in contrast to the interruption portion (P2) or lower portion (P3) located below, but the upper portion (P1) and overhang structure portion (P1a) and the remaining portion except this Divided by (P1b), the coil turn trend tends to be the same.

Specifically, the upper end P1 may include a first upper end P1a corresponding to the opening O and a second upper end P1b corresponding to the remaining part. The first upper end portion P1a has a funnel shape and corresponds to a portion having a larger diameter toward the top. The second upper end portion P1b corresponds to a portion having a diameter substantially the same as the diameter of the interruption portion and the lower end continuous below.

The coil pitch d1a of the first upper end P1a may be substantially the same as the coil pitch d1b of the second upper end P1b. For example, the coil pitch d1a and the coil pitch d1b may be the same.

As described above, since the coil pitch is influenced by the number of coil turns, it may mean that the smaller the coil pitch d1a is as small as the coil pitch d1b, the greater the number of coil turns relative to the middle portion or the lower end portion. That is, the coil pitch d1a for the first upper end P1a is smaller than the stop coil pitch d2 or the lower end coil pitch d3, so that the number of coil turns for the first upper end for the same length is the stop or the lower end. More than Similarly, the coil pitch d1b for the second upper end P1b is smaller than the stop coil pitch d2 or the lower end coil pitch d3 and thus the number of coil turns for the second upper end is greater than that of the stop or the lower end.

4 is a cross-sectional view illustrating a filament heater 200 and a crucible 10 mounted thereto for a thermal evaporator according to another embodiment of the present invention.

The temperature distribution control by adjusting the coil turns can be achieved even when the coil turns are increased from the lower end to the upper end of the crucible. Only the difference in the coil turn adjustment is different, the description of the remaining components can be applied to the same description as in FIG.

Referring to FIG. 4, the number of coil turns surrounding the upper end portion P1 may be greater than the number of coil turns surrounding the stop portion P2. The number of coil turns surrounding the stop P2 may be greater than the number of coil turns surrounding the lower end P3. That is, the number of coil turns may increase from the lower end P3 to the upper end P1 after passing through the stop P2.

For example, in FIG. 4, the number of coil turns enclosing the upper end P1 is 11, the number of coil turns enclosing the stop P2 is 5, and the number of coil turns encloses the lower end P3 is 4, and the upper coil turns 11 are stopped. More than the sub coil turn number 5 and the lower coil turn number 4, the interruption coil turn number 5 is also larger than the lower coil turn number 4. In other words, as the coil is wound from the lower end to the upper end, the heating element is concentrated on the upper end.

Therefore, the upper end portion P1 of the crucible is relatively higher in temperature than the other portions P2 or P3 due to the concentration of the heating element, thereby preventing the above-mentioned scattering problem of the organic material and clogging of the crucible top.

Referring to FIG. 4, the coil pitches d1, d2 and d3 ′ for each crucible part are shown together.

As described above, when the filament is coiled with respect to the winding object having one winding axis, the coil pitch becomes narrower as the number of coil turns increases, so that the coil pitch d1 surrounding the upper end P1 is the interruption part P2 or the lower end part. It may be smaller than the coil pitch d2 or d3 'surrounding (P3). In addition, the coil pitch d2 surrounding the stop portion P2 may be smaller than the coil pitch d3 ′ surrounding the lower end portion P3.

As such, by narrowing the coil pitch from the lower end to the upper end, the heating element is concentrated on the upper end of the crucible and the temperature of the upper end of the crucible can be formed relatively higher than other parts.

Meanwhile, in FIG. 4, the coil pitch is narrower from the lower end to the upper end, so that the coil pitch d1a at the first upper end P1a is smaller than the coil pitch d1b at the second upper end P1b. Can be. Even in this case, the upper end portion including the first upper end portion and the second upper end portion has more coil turns than the interruption portion or the lower end portion located below it, and thus the coil pitch is also formed smaller, thereby concentrating the heating element on the upper end portion.

5 is a view showing a comparative example of the use of the crucible to which the filament heater for the thermal evaporator according to an embodiment of the present invention is applied. 5A shows a conventional use example and FIG. 5B shows a use example of the present invention, respectively.

First, as shown in FIG. 5A, in a crucible to which a conventional filament heater for a thermal evaporator is applied, about 5 mm deposition growth is observed from the side of the upper end of the crucible after 1000 nm deposition. This side deposition growth is directly related to the crucible blockage phenomenon.

In contrast, as shown in FIG. 5B, in the crucible to which the filament heater for the thermal evaporator according to the embodiment of the present invention is applied, the crucible blockage does not occur even after 5000 nm deposition. Only crucible top side deposition growth of less than about 0.1 mm is observed. As the number of coils on the top of the crucible is increased, the temperature is relatively increased due to the concentration of the heating element, which causes sublimation (vaporization) of the material on the top of the crucible, thereby preventing the material from scattering. This is because the blockage caused by the redeposition of the material was significantly reduced.

According to the embodiment of the present invention, it is possible to improve the process yield by improving the problem of the existing heater at a low cost. In addition, material scattering and crucible blockage can be prevented regardless of the type of material for organic material deposition. In addition, the overall process time can be shortened by improving the reliability of the deposited thin film, simplifying the loading process through the application of high capacity crucibles independent of materials, and reducing the preheating time.

Although the technical spirit of the present invention has been specifically recorded in accordance with the above-described preferred embodiments, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, one of ordinary skill in the art will appreciate that various embodiments are possible within the spirit of the present invention.

10: crucible
100, 200: filament heater
S: organic material
O: opening
B: torso
E: Extension
T: tunnel part
P1: upper part
P2: interruption
P3: lower part

Claims (7)

In filament heater for thermal evaporator,
It has a coil shape surrounding the outer surface of the container containing the organic material,
The coil shape is a filament heater for a thermal evaporator, the number of coil turns for each container portion is variable. The method of claim 1,
The container is divided into a continuous top portion, a stop portion and a lower portion,
A filament heater for a thermal evaporator, wherein the number of coil turns surrounding the upper end is greater than the number of coil turns surrounding the interruption or the lower end. The method of claim 2,
Filament heater for the thermal evaporator having a tendency to increase the number of coil turns from the lower end to the upper end beyond the interruption. The method of claim 2,
The upper end includes a first upper end having a diameter larger than the stop or the lower end, and a second upper end having the same diameter as the stop or the lower end,
The first upper end portion has a funnel shape that increases in diameter toward the uppermost portion,
A filament heater for a thermal evaporator, wherein the number of coil turns surrounding the first and second upper ends is greater than the number of coil turns surrounding the interruption or the lower end. The method of claim 2,
A filament heater for a thermal evaporator, wherein the coil pitch surrounding the upper end is smaller than the coil pitch surrounding the interruption or the lower end. The method of claim 3,
Filament heater for the thermal evaporator having a tendency to narrow the coil pitch from the lower end to the upper end beyond the interruption. The method of claim 4, wherein
The coil pitch surrounding the first upper end is equivalent to the coil pitch surrounding the second upper end.

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