KR20220039772A - Crucible for vapor deposition - Google Patents

Abstract

The crucible for deposition according to the present embodiment includes a lower body having a cylindrical shape in which deposition raw materials are contained; an upper body extending above the lower body and evaporating a deposition material; and a plurality of pockets formed on the inner bottom surface of the lower body and formed in an annular shape coincident with the center of the lower body.

Description

Crucible for vapor deposition

The present invention relates to a crucible for deposition capable of improving damage caused by thermal stress.

Deposition is a method of coating gaseous particles with a thin solid film on the surface of an object such as metal or glass.

Recently, as the use of OLED (Organic Light Emitting Diodes) displays increases in electronic devices such as TVs and mobile phones, research on devices for manufacturing OLED display panels is active. In particular, the OLED display panel manufacturing process includes a process of depositing an organic material or an inorganic material on a glass substrate in a vacuum state.

The deposition process is a process of heating a crucible in which a deposition raw material such as an organic/inorganic material is accommodated to evaporate the deposition raw material into a gaseous deposition material, and the gaseous deposition material passes through a nozzle and is deposited on the substrate. includes the process.

Unlike organic materials, inorganic materials may include metals, and metals such as Al, Ag, and Mg used to form a metal thin film are used as deposition materials.

In order to evaporate the metal deposition raw material, the crucible must be heated to a high temperature of 700° C. or higher, and thermal stress may be applied to deteriorate the durability of the crucible.

Korean Patent Registration No. 1757925 (filed on Nov. 26, 2010) discloses a crucible having a body in which the deposition material is contained and a nozzle in which the deposition material is evaporated, and the thickness of the lower body is thicker than that of the upper body; and first, second, and third inner plates seated on the crucible nozzle; a crucible for deposition comprising a; and a deposition apparatus using the same are disclosed.

The crucible is (U)-shaped, and the thickness of the body is configured to be thicker as it goes down from the top to the bottom, and is installed to be accommodated in the heater.

When a deposition raw material such as aluminum is used, aluminum melts the latest at the lower side of the crucible and solidifies the fastest, and even if aluminum expands due to the structure of the crucible, breakage or cracking of the crucible can be prevented.

1 is a view showing a thermal stress distribution of a crucible for deposition according to the prior art.

According to the prior art, it can be confirmed that the maximum thermal stress appears at the boundary between the surface of the deposition material and the inner circumferential surface of the crucible as shown in FIG. can

However, according to the above technique, since the entire crucible cannot be uniformly heated or cooled to the same temperature, even if the lower thickness of the crucible is increased, the thermal stress generated according to the difference in the actual thermal expansion coefficient and the temperature distribution cannot be reduced. .

In addition, since the lower thickness of the crucible is increased, a temperature difference between the inner/outer walls of the crucible is greatly generated during cooling, and thus thermal stress is greatly applied to the crucible, which may further cause breakage or cracking of the crucible.

The present invention has been devised to solve the problems of the prior art, and an object of the present invention is to provide a crucible for deposition capable of improving damage caused by thermal stress.

The crucible for deposition according to the present embodiment includes a lower body having a cylindrical shape in which deposition raw materials are contained; an upper body extending above the lower body and evaporating a deposition material; and a plurality of pockets formed on the inner bottom surface of the lower body and formed in an annular shape coincident with the center of the lower body.

The pockets may be arranged to be spaced apart from each other in a radial direction.

The pockets may be formed to have the same thickness in the radial direction.

The pockets may be formed to have the same height in the vertical direction.

The pockets may be formed to be less than 20% of the height of the lower body.

The lower body may include a step portion in which the inner diameter is rapidly reduced at the connection portion with the upper body.

The upper body may have an inner diameter gradually increasing from the lower side to the upper side, and may be formed to have a height lower than the height of the lower body.

The crucible for mounting may be made of a material having a smaller coefficient of thermal expansion than the deposition material, and may be made of a ceramic composite material.

The crucible for deposition according to this embodiment is provided with annular pockets on the inner bottom surface, so that thermal stress affected by the temperature distribution difference can be minimized, and the strength of the crucible is reinforced in structure in which partition walls are provided between the annular pockets. Therefore, it is possible to prevent breakage or cracking of the crucible as well as increase the durability of the crucible.

1 is a view showing a thermal stress distribution of a crucible for deposition according to the prior art.
2 to 4 are views showing a crucible for deposition according to the present embodiment.
5 is a view showing the thermal stress distribution of Comparative Examples and Examples.

2 to 4 are views showing a crucible for deposition according to the present embodiment.

The crucible 100 of this embodiment is for evaporating a deposition material made of a metal material such as aluminum into a deposition material, and includes a lower body 110, an upper body 120, annular pockets 130, and partitions ( 140) can be configured.

The deposition raw material is a material in a solid/liquid state that is filled in the crucible 100, and the deposition material is a gaseous material evaporated in the crucible 100. The deposition raw material and the deposition material are the same, and are separated for convenience of explanation. only, and need not be limited.

The lower body 110 is configured in a container shape provided with a groove 110h in which the deposition material is contained, and may include a cylinder part 111 , a bottom part 112 , and a step part 113 .

The cylinder part 111 may have a cylindrical shape having a constant inner diameter D1 and a predetermined height H, and may provide a space in which a deposition material can be accommodated.

The bottom part 112 is a closed portion on the lower side of the cylinder part 111 , and pockets 130 and partition walls 140 to be described below may be provided.

The stepped portion 113 is a portion whose inner diameter is abruptly narrowed on the upper side of the cylinder portion 111 , and when the deposition material is evaporated from the step portion 113 , the internal pressure may be high to spread the deposition material further away. The step portion 113 may be inclined upward at an angle of 45° or less, or may be formed horizontally, but is not limited thereto.

The upper body 120 is configured in the shape of a flow path provided with a hole 120h through which the deposition material in which the deposition raw material is vaporized passes, and may include an inclined portion 121 and a flange portion 122 .

The inclined portion 121 communicates with the upper side of the stepped portion 113 , and has a cylindrical shape with an inner diameter narrowing toward the upper side, and may provide a flow path through which the deposition material may be diffused. Of course, the lower inner diameter D2 of the inclined portion 121 may be the smallest and the upper inner diameter D3 of the inclined portion 121 may be the largest.

The flange portion 122 is a radially extended portion on the upper end of the inclined portion 121 , and a heater (not shown) may be mounted on the lower side of the flange portion 122 , that is, on the outer peripheral surfaces of the upper/lower bodies 110 and 120 .

The upper body 120 is integrally configured on the upper side of the lower body 110, and the groove 110h of the lower body and the hole 120h of the upper body communicate with each other, and the center thereof may be configured to coincide.

The upper body 120 may be formed to have a height lower than the height H of the lower body 110 , and the deposition material in which the deposition raw material is vaporized in the lower body 110 moves upward through the upper body 120 . Let it escape and spread.

The pocket portion 130 and the partition walls 140 are formed on the inner bottom surface of the lower body 110, and the annular pocket portion 130 and the annular partition wall 140 may be alternately disposed in the radial direction one by one. That is, the pockets 130 may be provided between the partition walls 140 .

Of course, the centers of the pockets 130 and the partition walls 140 may be arranged to coincide with the centers of the cylinder part 111 and the bottom part 112 .

The pockets 130 provide a space for accommodating a liquid deposition raw material, and the partition walls 140 may be provided to form annular pockets 130 in a radial direction.

The pockets 130 are formed to have a larger diameter from the inside to the outside, but may be configured to have the same thickness t1 in the radial direction and the same height h in the vertical direction.

It can be seen that the pockets 130 are radially spaced apart from each other by the thickness t2 of the partition walls 140 . Similarly, it can be seen that the partition walls 140 are spaced apart from each other in the radial direction by the thickness t1 of the pockets 130 .

However, when the pockets 130 and the partition walls 140 are formed inside the lower body 110, the remaining internal space of the lower body 110 except for the space where the pockets 130 and the partition walls 140 are formed. A solid state deposition raw material may be input, and the deposition raw material may be heated in the corresponding space.

Accordingly, the height h of the pockets 130 may be determined based on the height H of the lower body 110 in consideration of the input and heating space of the deposition material. The height (h) of the pockets 130 may be formed to be 20% or less of the height (H) of the lower body 110, but is not limited thereto.

The crucible 100 for deposition configured as described above is used under a high temperature capable of melting a metal deposition raw material, and should be made of a material that can withstand high temperature, and is preferably made of a material having a smaller coefficient of thermal expansion than the deposition material. .

The crucible 100 for deposition may be made of a ceramic composite material that can withstand high temperatures and has the strength to withstand thermal stress, but is not limited thereto.

A process performed in the crucible for deposition configured as described above will be described as follows.

Aluminum in a solid state may be put into the crucible, and the crucible may be gradually heated. When the melting temperature is 650°C, the solid aluminum starts to melt, and when the vaporization temperature is 1000°C or higher, the liquid aluminum is vaporized.

The deposition material vaporized in the crucible flows out to the upper side of the crucible, and the particles of the diffused deposition material come into contact with the deposition target and solidify, thereby forming an aluminum thin film on the deposition target.

When the deposition process is completed, a cool down process of lowering the temperature of the crucible may be performed. When the melting temperature is 650° C. or lower, the remaining aluminum undergoes a phase change from a liquid phase to a solid phase.

As aluminum shrinks, the crucible also contracts. Since aluminum, a deposition material, has a larger thermal expansion coefficient than ceramic, which is a material of the crucible, thermal stress is applied to the crucible due to the difference in thermal expansion coefficient.

However, as the annular pockets and the annular partition walls are applied to the inner bottom surface of the crucible, a phase change occurs in a state in which liquid aluminum is accommodated in the pockets and fused with the partition walls.

Therefore, by dividing the inner space of the crucible into annular pockets, the thermal stress affected by the temperature distribution difference can be minimized and the strength of the crucible can be reinforced structurally, thereby preventing damage or cracking of the crucible as well as It is possible to increase the durability of the crucible.

5 is a view showing the thermal stress distribution of Comparative Examples and Examples.

The comparative example is a form in which pockets and partition walls are not formed on the inner bottom surface of the crucible. As a result of measuring the thermal stress at points 1 to 8, the average thermal stress is 3350 MPa and the maximum thermal stress is 4770 MPa.

On the other hand, the Example is a form in which pockets and partition walls are formed on the inner bottom surface of the crucible, and as a result of measuring the same points 1 to 8 as in Comparative Example, the average thermal stress is 2170 MPa and the maximum thermal stress is 3530 MPa.

Compared to the comparative example, it can be seen that the embodiment reduced the average thermal stress by about 65% and the maximum thermal stress by about 75%.

The above description is merely illustrative of the technical spirit of the present invention, and various modifications and variations will be possible without departing from the essential characteristics of the present invention by those skilled in the art to which the present invention pertains.

Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments.

The protection scope of the present invention should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

This embodiment can be applied to a crucible for deposition in which a metal material is deposited in a thin film shape on a glass substrate when manufacturing an OLED display panel.

Claims (10)

The lower body of the cylindrical shape containing the deposition material;
an upper body extending above the lower body and evaporating a deposition material; and
A deposition crucible comprising a; a plurality of pockets formed on the inner bottom surface of the lower body, and formed in an annular shape coincident with the center of the lower body. According to claim 1,
The pockets are
A crucible for deposition that is arranged to maintain a certain distance in the radial direction. According to claim 1,
The pockets are
A crucible for deposition that is formed to have the same thickness in the radial direction. According to claim 1,
The pockets are
A crucible for deposition that is formed to have the same height in the vertical direction. According to claim 1,
The pockets are
A crucible for deposition that is formed to be 20% or less of the height of the lower body. According to claim 1,
The lower body is
A crucible for mounting including a step portion in which the inner diameter is rapidly reduced in the upper body and the connection portion. 7. The method of claim 6,
The upper body is
A crucible for mounting whose inner diameter gradually increases from the lower side to the upper side. 8. The method of claim 7,
The upper body is
A crucible for mounting that is formed to have a height lower than the height of the lower body. According to claim 1,
The crucible for mounting,
A crucible for mounting composed of a material having a smaller coefficient of thermal expansion than the deposition material. 10. The method of claim 9,
The crucible for mounting,
Mounting crucible made of ceramic composite material.

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