KR101266584B1 - Evaporation source for Large scale deposition using parallel connection of point source - Google Patents

Abstract

The present invention relates to an evaporation source for a large area deposition, and is made by linearly arranging a plurality of modular heating elements, crucibles and reflecting plates. The plurality of heating elements are connected in parallel with the common electrode blocks at predetermined intervals between the heating elements, and individual crucibles and reflectors are provided for each of the heating elements to form an evaporation source capable of depositing a large area. The common electrode block flows cooling water to prevent overheating. The combination of individual heating elements, crucibles and reflectors can be regarded as an approximate point evaporation source, and the uniformity of the large area deposition is ensured by controlling the distance between the point evaporation sources. Therefore, the evaporation source using the parallel-connected heating element structure of the present invention is an invention device that can prevent thermal deformation and breakage of the evaporation source while ensuring uniformity for large area deposition.

Description

Evaporation source for Large scale deposition using parallel connection of point source}

The present invention relates to an evaporation source fabrication technology for large-area thin film deposition required in semiconductor and display processes. In particular, it is a technology that can be applied to a metal evaporation source that requires high temperature heating.

In the manufacturing process of semiconductor devices, display panels, and solar cells, vacuum deposition is mainly used to fabricate high purity and uniform thin films. The vacuum deposition methods are mainly physical vapor deposition (PVD) and chemical vapor deposition. Chemical vapor deposition (CVD) can be divided into deposition methods. Among them, vacuum evaporation (Thermal evaporation) is a physical vapor deposition method commonly used for manufacturing organic light emitting devices or solar cells. In the vacuum heating deposition method, an evaporation source containing an evaporation material source is placed in a vacuum chamber, and the evaporation material is deposited on a substrate in the same vacuum chamber by heating it. The simplest form of evaporation source used in vacuum heating evaporation is the point evaporation source, commonly referred to as Knudsen cell. A general point evaporation source is composed of a crucible containing a deposition raw material, a heating element capable of heating the crucible, and a predetermined opening which is a passage through which raw material evaporated from the crucible is ejected. This point evaporation source is sprayed the most raw material in the direction perpendicular to the opening, and since the material injection rate is changed drastically according to the injection direction, it is difficult to apply even if the substrate size is only 370x470 mm or more. In order to overcome the limitation of point evaporation source, a method of rotating the substrate or depositing on an obliquely inclined substrate is used, but it is also not suitable for large area substrate deposition. The evaporation source used for conventional large area substrate deposition is mainly a linear evaporation source as shown in FIG. The elongated linear nozzle 50 of the linear evaporation source cancels the effect of reducing the amount of raw material injection at the edge, and is relatively narrow at the center for uniform thin film deposition, and has a wider shape toward the edge. The linear evaporation source for large area deposition has a disadvantage in that it is vulnerable to heat deformation because of its length, and it is difficult to obtain a uniform temperature distribution when heated. In the case of a metal evaporation source using an indirect heating method, the difference in thermal expansion coefficient between the crucible and the heating element has a problem of causing deformation and breakage of the evaporation source. This tendency is exacerbated in metal evaporation sources that require high evaporation temperatures such as Cu. In addition, it is difficult to accurately predict the nozzle shape of the linear evaporation source that can obtain a uniform thin film thickness.

Vacuum heating evaporation can be divided into bottom-up, top-down, or vertical type depending on the relative position between the evaporation source and the substrate.In organic light-emitting device fabrication, the bottom-up method where the evaporation source is located under the substrate is often used. In the case of solar cell fabrication, since the substrate sag is severe, it is preferable to perform top-down deposition. Linear evaporation sources for large-area deposition, bottom-up or top-down, suffer from the problems of breakage, temperature unevenness due to thermal deformation, and include common drawbacks that are difficult to optimize opening shape.

Accordingly, an object of the present invention is to provide an evaporation source device capable of uniform thin film deposition as an evaporation source for large area thin film deposition and without evaporation source damage due to heat deformation at high temperature.

The present invention relates to a common electrode block located in a deposition chamber connected to two poles of an external power supply.

 Heating elements having a plurality of the same characteristics connected in parallel to the common electrode block,

 In addition, the present invention provides an evaporation source for large-area thin film deposition, which consists of a linear arrangement of crucibles that are in one-to-one correspondence with the heating elements and indirectly heated by the heating elements.

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The crucibles include a bottom-up or a downward nozzle as a passage for injecting the deposition raw material, and the heating element surrounding the crucible prevents thermal energy loss by surrounding the outside of the heating element with a reflector insulated by a predetermined insulation.

A common electrode block connected to both ends of a plurality of heating elements connected in parallel has a predetermined cooling water line, thereby forming an evaporation source structure that prevents overheating of the electrode block and reduces heat energy loss.

Therefore, the present invention,
A linear common electrode block connected to the + and − poles of the external power supply, respectively;
A plurality of evaporation sources electrically connected in parallel to the common electrode block and arranged at intervals from each other; And

The common electrode block may provide a large-area deposition evaporation source including a connection groove having a predetermined length in which the evaporation source is in contact with the common electrode block so that the arrangement interval of the plurality of evaporation sources can be adjusted. have.

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In addition, the present invention, in the deposition evaporation source, the plurality of evaporation source may provide a large-area deposition evaporation source characterized in that arranged so that the arrangement interval is narrowed toward the end from the center of the linear common electrode block toward the end. .

In addition, the present invention, in the deposition evaporation source, each of the evaporation source,

Respective heating elements electrically connected to the common electrode block;

A crucible seated in the heating element and indirectly heated; And

It can provide a large-area deposition evaporation source comprising a; reflecting plate surrounding the heating element.

In addition, the present invention, in the deposition evaporation source, the crucible may provide a large-area deposition evaporation source, characterized in that configured in the bottom-up, top-down or vertical.

In addition, the present invention, in the deposition evaporation source, the heating element may provide a large-area deposition evaporation source, characterized in that the coil, mesh or plate configuration.

In addition, the present invention, in the vapor deposition evaporation source, the reflecting plate can be provided with a large-area vapor deposition evaporation source, characterized in that it is fitted in a ring member made of an insulator, consisting of a plurality of layers.

According to the present invention, in the construction of an evaporation source for a large area deposition, a plurality of evaporation sources connected in parallel through a common electrode block can be used to adjust the positions of individual evaporation sources to ensure uniformity of the thin film during large area deposition. By installing a cooling water line in the common electrode block, it is possible to prevent thermal deformation and breakage of the entire evaporation source. In addition, the evaporation source for the large-area deposition is composed of a combination of a modular heating element, crucible, reflector plate, it is easy to maintain and reduce the maintenance cost.

1 is a schematic diagram showing a conventional linear evaporation source for large area deposition.
Figure 2 is a plan view schematically showing an embodiment of a parallel connection heating element structure of the present invention.
Figure 3 is a perspective view showing an embodiment of a parallel connection heating element structure of the present invention.
4 is a schematic diagram illustrating an embodiment in which a connection unit connecting between the parallel connection heating element and the common electrode block of the present invention is configured.
5 is a cross-sectional view showing a state in which the heating element and the common electrode block of the present invention are connected by a connecting portion.
6 is a schematic cross-sectional view and a cross-sectional view schematically illustrating a crucible, a reflector, and a heating unit of a top-down large-area evaporation source to which a parallel connection heating element of the present invention is applied.
7 is a schematic diagram of a plate-like heating element and a mesh (mesh) heating element which are embodiments of the heating element of the present invention.
8 is a cross-sectional view showing a bottom-up crucible is applied in another embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the present invention as a means for solving the above problems, as shown in the embodiment shown in Figure 2 by connecting a plurality of separate heating element 120 in the form of parallel connection between the two common electrode block heating method of the evaporation source for large area deposition Used as Each of the heating elements 120 is wound around a refractory metal (W, Ta, Mo, etc.) wire in the form of a coil, one end of the wire to the positive electrode block 100, which is a common electrode block, and the other end to the cathode It is connected to the (-) electrode block 110. This connection allows each of the heating elements 120 to be connected in parallel with each other. The common electrode block is made longer than the length of the substrate to be deposited, and connects the plurality of heating elements 120 along the side of the long linear electrode block. The common electrode block is made of Cu or STS material, and has a coolant line 190 to flow coolant. An electrode support 130 made of an insulator is connected between the two positive electrode blocks and the negative electrode block. In FIG. 2, nine heating elements 120 are connected between two common electrode blocks. Each coil-shaped heating element 120 is heated inside by placing a crucible as shown in FIG. 6 in each heating element 120. This enables deposition of a deposition raw material onto a substrate, which is injected from a plurality of heated crucibles into a gas in a molecular beam state. Here, the combination of each heating element, crucible, and reflector to be described later can be seen as an evaporation source, and in the present invention, a linear evaporation source that can cover a large area substrate can be regarded as being formed by linearly arranging a plurality of evaporation sources. In order to secure deposition uniformity, two methods may be used to reduce the distance between the evaporation sources arranged to the edge, or to increase the size of the opening from which the material is injected from each evaporation source toward the edge. As shown in Fig. 3, the method of controlling the distance between evaporation sources is used. 3 is a perspective view in which a spiral coil-shaped heating element 120 is connected to the common electrode block shown in FIG. The detailed configuration of the coil-shaped heating element 120, the common electrode block and the connecting portion is shown in FIG. Both ends of the wires forming the heating element 120 are placed on the connection grooves 140 processed at a height slightly lower than the wire diameter on each common electrode block, and then the wire fixing plate 150 made of the same material as the electrode block thereon. It is fixed to the connection screw # 1 (160) and the connection screw # 2 (170) to form a connection. The connecting groove 140 is formed to have a predetermined width in the left and right (the longitudinal direction of the linear evaporation source), the slot 180 of the wire fixing plate through which the connecting screw 160, 170 penetrates also long left and right, the heating element 120 The left and right positions of the) is to be adjusted in the sliding groove 140 in a sliding manner. Therefore, it is a structure that can be used to control the uniform source flux distribution by adjusting the interval of the evaporation source by adjusting the position of the evaporation source as needed.

As described above, the heating element 120 and the common electrode structure connected in parallel in FIGS. 2 and 3 may prevent breakage due to thermal deformation and thermal expansion. Since the common electrode block is cooled through the coolant line, there is little thermal deformation. In addition, since the heating element 120 can be made very small compared to the overall substrate size, it is possible to minimize thermal deformation and thermal expansion, thereby preventing damage. By using a parallel connection heating unit (including a heating element and a reflector to be described later) according to the present invention, the crucible can also be made much smaller than the required large area substrate size, thereby minimizing thermal deformation.

In addition, as a variation of the above embodiment, the crucible and the heating element may be constituted by a direct heating type evaporation source capable of electrically connecting the crucible itself to an electric connection.

5 and 6 are cross-sectional views of a large-area Cu evaporation source applicable to 600X1200 or more that can be used in CIGS thin film solar cells by applying a top-down crucible structure as an embodiment of the large-area evaporation source using the parallel connection heating unit of the present invention. Is shown in detail. The cross-sectional view shows only one of a plurality of parallel-connected heating units and crucibles at that location. 5 is a cross-sectional view illustrating an embodiment in which a heating unit, a common electrode block, and a connecting unit are configured. The heating element 120 is made of a wire wound in the shape of a spiral coil, and both ends of the heating element 120 are positioned in the connection groove 140, and then the wire fixing plate 150 and the common electrode block are connected with the connection screw 160 and 170. The fastening is connected to the positive electrode block 100 and the negative electrode block 110. Cooling water lines 190 are provided in the electrode blocks 100 and 110 to prevent deformation and damage of the evaporation source due to overheating of the electrode block. 6 illustrates the top down crucible 300 and the reflecting plates 230 and 240 together. The top-down crucible 300 is a method in which the deposition raw material evaporated from the crucible body 260 is reflected from the top of the crucible closed by the crucible lid 250 and is discharged downward through the nozzle 270 at the center of the crucible. The crucible lid 250 is screwed to open and close to facilitate refilling of the deposition raw material while preventing leakage of the deposition raw material. The crucible 300 is inserted into the center of the heating element 120, maintains a predetermined distance from the heating element 120 and wraps the outside of the heating element 120 with the primary reflector 230 and the secondary reflector 240 to generate the heating element 120. ) And the thermal energy loss of the crucible 300, and the heating of the crucible 300 can be efficient. It is preferable that the primary and secondary reflecting plates 230 and 240 be made by stacking a plurality of thin Ta plates. The reflector plates 230 and 240 may be formed in a cylindrical shape and follow a circular arc on one side of a ring made of an insulator as shown in FIG. 6 so as to be insulated from the common electrode blocks 100 and 110 and the heating element 120. A groove is formed and the edges of the reflecting plates 230 and 240 are sandwiched and then positioned between the common electrode blocks 100 and 110 and the heating element 120. More specifically, between the lower portion of the upper insulating ring 200 and the groove of the upper end of the lower insulating ring 220 and the lower reflection plate 230 and the primary reflecting plate 230 is inserted between the groove of the upper end of the central insulating ring (210). There is a second primary reflector 230 to be fitted to the outer, the outer side of the upper secondary insulating ring 200 and the cylindrical secondary reflector 240 having a radius slightly larger than the primary reflecting plate 230 It is a structure that is to be fitted into a predetermined groove formed in the same radius as the second reflecting plate 240 on the top. The insulating ring is preferably made of a ceramic insulator such as boron nitride. In this way, it is possible to provide a reflector plate structure surrounding the crucible with a small and concise structure.

The evaporation source for the large-area deposition of the present invention includes a crucible 300, a heating element 120, a primary and secondary reflector plates 230 and 240, and upper, middle and lower insulating rings 200, 210 and 220 shown in cross-sectional view in FIG. ) Are modular. That is, the crucible 300, the heating element 120, the first and second reflecting plates 230 and 240 and the upper, center, and lower insulating rings 200, 210 and 220 shown in FIG. 6 are assembled to form one evaporation source module. As shown in the embodiments of FIGS. 2 and 3, many of these evaporation source modules are linearly arranged in parallel between common electrode blocks to implement an evaporation source for large area deposition. In the embodiment of Figures 2 and 3, nine evaporation source modules were used. Because of this modularity, maintenance and failures can be handled by modules, reducing maintenance costs.

Another embodiment of the present invention is to replace the heating element in the form of a thin plate surrounding the crucible instead of the wire coil as a heating element connected in parallel.

Another embodiment of the present invention is to replace the heating coil of the mesh type surrounding the crucible instead of the wire coil as a heating element connected in parallel. FIG. 7 schematically illustrates an embodiment of a thin plate type heating element and a net type heating element that may replace the wire coil.

Another embodiment of the present invention is to replace the bottom-up crucible with the bottom-up crucible to constitute the large-area deposition evaporation source of the present invention. As briefly shown in Figure 8 in the configuration of the present invention by changing only the crucible up-top crucible 310 is inserted into a parallel connection heating element to produce a bottom-up large area evaporation source is the same effect of the present invention.

The configuration of the present invention is not limited to the above-described embodiments, and it is obvious that various applications and modifications can be made by those skilled in the art.

50: linear nozzle 100: anode electrode block
110: cathode electrode block 120: heating element
130: electrode support 140: connection groove
150: wire fixing plate 160: connection screw # 1
170: connecting screw # 2 180: (fixing plate) slot
190: coolant line 200: upper insulation ring
210: center insulation ring 220: lower insulation ring
230: primary reflector 240: secondary reflector
250: crucible lid 260: crucible body
300: top down crucible 310: top down crucible

Claims (7)

A linear common electrode block connected to the + and − poles of the external power supply, respectively;
A plurality of evaporation sources electrically connected in parallel to the common electrode block and arranged at intervals from each other; And
And the common electrode block includes a connection groove having a predetermined length in which the evaporation source is in contact with the common electrode block so that an arrangement interval of the plurality of evaporation sources can be adjusted.
delete The large area deposition evaporation source of claim 1, wherein the plurality of evaporation sources are arranged such that the arrangement intervals become narrower from the center portion of the linear common electrode block toward the end portion. The method according to claim 1, wherein each of the incremental sources,
Respective heating elements electrically connected to the common electrode block;
A crucible seated in the heating element and indirectly heated; And
Large area deposition evaporation source comprising a; reflecting plate surrounding the heating element. 5. The large area deposition evaporation source according to claim 4, wherein the crucible is configured in a bottom-up, top-down, or vertical form. The large-area vapor deposition evaporation source according to claim 4, wherein the heating element is formed in a coil shape, a mesh shape, or a plate shape. 5. The large-area vapor deposition evaporation source according to claim 4, wherein the reflector is fitted in a ring member made of an insulator and is formed of several layers.

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