KR20180131793A - Method for Manufacturing Ceramic Heater - Google Patents

Abstract

The present invention relates to a method for manufacturing a ceramic heater which comprises the steps of: forming a laminate structure of a sandwich structure having a ceramic powder layer in which a heating body is embedded interposed between first and second ceramic blocking layers; and sintering a molded body of the laminate structure. The method performs sintering using the ceramic blocking layer which improves a local resistance change rate of the heating body.

Description

TECHNICAL FIELD The present invention relates to a method of manufacturing a ceramic heater,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a ceramic heater, and more particularly, to a method of manufacturing a ceramic heater that improves local rate of resistance change of a heating element.

The ceramic heater is used for heat-treating a heat treatment object for various purposes such as a semiconductor wafer, a glass substrate, and a flexible substrate at a predetermined heating temperature. Ceramic heaters are used in combination with the functions of electrostatic chucks for semiconductor wafer processing. Generally, a ceramic heater includes a ceramic plate that generates heat by receiving power from an external electrode. The ceramic plate includes a heating element having a predetermined resistance buried in the ceramic sintered body.

No. 10-0533471 (December 06, 2005) and the like can be referred to as related prior arts. Japanese Patent Application No. 10-0533471 discloses a ceramic heater for suppressing carbonization of a built-in heating element by sintering a molded body in contact with upper and lower parts of the ceramic plate in contact with at least one metal dummy member selected from the elements in the periodic table 4a, 5a, . However, such a conventional method of manufacturing a ceramic heater of a metallic dummy type poses various problems.

First, the ceramic heater manufactured by the metal dummy method has a local resistance irregularity depending on the heating element part. Next, in the conventional metal dummy method, the metal dummy member is a one-time consumable part which must be removed after manufacture and is difficult to be reused. Further, in the conventional metal dummy method, the carbide formed by the carbonization of the metal dummy member causes damage to the surface of the ceramic heater sintered body in contact with the ceramic sintered body. However, the thickness of the ceramic heater becomes thicker than necessary .

The inventors of the present invention have found that, in the method of using the conventional metal dummy member, the metal dummy member reacts with the carbide during sintering to exhibit brittleness, thereby causing cracking. Further, the inventors of the present invention have found that the carbon source acting as a factor of the resistance change of the heating element is caused by the carbon sources in the external sources, that is, the carbon mold or the furnace, rather than the carbon content in the powder. Therefore, the cracks formed in the introduced metal dummy member act as inflow passages for carbon originating from other carbon sources in the furnace, such as the carbon mold or the carbon members, and are therefore suitable for suppressing the inflow of carbon derived from the outside of the molded body And the carbonization of the heating element can not be sufficiently suppressed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a ceramic heater in which a sintering process is performed using a ceramic barrier layer for improving a local rate of resistance change of a heating element, And to provide a ceramic heater.

It is another object of the present invention to provide a method of manufacturing a ceramic heater using a reusable ceramic barrier layer for suppressing carbonization and a ceramic heater manufactured by the method.

It is another object of the present invention to provide a method of manufacturing a ceramic heater capable of appropriately maintaining the thickness of a sintered body and a ceramic heater manufactured by the method.

A method of manufacturing a ceramic heater according to an aspect of the present invention includes the steps of forming a ceramic powder having a heating element embedded between a first ceramic barrier layer and a second ceramic barrier layer, Forming a laminated structure of a sandwich structure in which a layer is interposed; And sintering the formed body of the laminated structure.

The forming of the laminate structure may include: providing the first ceramic barrier layer; Providing the ceramic powder layer on which the heating element is embedded on the first ceramic barrier layer; And providing the second ceramic barrier layer on the ceramic powder layer.

Providing the ceramic powder layer comprises: providing a first ceramic powder layer; Disposing the heating element on the first ceramic powder layer; And providing a second ceramic powder layer on the first ceramic powder layer on which the heating element is disposed.

In the step of providing the first ceramic powder layer, the first ceramic powder layer may be a molded body.

The method further comprises a step of press-molding the first ceramic powder layer, the heating element and the second ceramic powder layer after the second ceramic powder layer providing step.

An inert layer containing boron nitride (BN) is interposed between each of the first and second ceramic barrier layers and the ceramic powder layer.

The first and second ceramic barrier layers comprise rare earth oxides.

Wherein the first and second ceramic barrier layers comprise nitride and rare earth oxides, wherein the rare earth oxide is less than 10 wt% of the ceramic barrier layer.

The first and second ceramic barrier layers are preferably sintered bodies.

The first and second ceramic barrier layers reduce the local generation of carbide due to the reaction with the carbon introduced from the outside in the heating element during the sintering process.

According to another aspect of the present invention, there is provided a ceramic heater comprising a ceramic sintered body and a heating element buried in the ceramic sintered body, wherein the ceramic sintered body has, between the first ceramic block layer and the second ceramic block layer, The ceramic powder layer is formed by forming a compact having a laminated structure of a sandwich structure in which a ceramic powder layer is interposed, and then sintering the ceramic powder layer.

According to the method for manufacturing a ceramic heater according to the present invention, a ceramic barrier layer is formed above and below a ceramic powder compact in which a heating element is buried, thereby improving the local resistance change rate of the heating element in the sintering process. That is, since the increase in resistance of the local heating element is blocked by the use of the ceramic barrier layer, the temperature deviation of the heating surface of the target body such as the wafer is remarkably reduced, and the temperature uniformity of the heating surface can be increased.

Further, in the prior art, there is a problem that the sintered ceramic powder must be made thicker than necessary in order to suppress the occurrence of scratches on the surface of the product. However, in the present invention, cracks are not generated by using the ceramic barrier layer, Can be reduced and the amount of ceramic used can be reduced.

1 is a view for explaining a ceramic heater according to an embodiment of the present invention.
2 is a flowchart illustrating a process of manufacturing a ceramic heater according to an embodiment of the present invention.
FIG. 3 is a view for explaining the comparison of the rate of resistance change according to conditions in the conventional ceramic heater and the heating element of the ceramic heater according to the embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same components are denoted by the same reference symbols as possible. In addition, detailed descriptions of known functions and / or configurations are omitted. The following description will focus on the parts necessary for understanding the operation according to various embodiments, and a description of elements that may obscure the gist of the description will be omitted. Also, some of the elements of the drawings may be exaggerated, omitted, or schematically illustrated. The size of each component does not entirely reflect the actual size, and therefore the contents described herein are not limited by the relative sizes or spacings of the components drawn in the respective drawings. In the present invention, 'lamination' is used to define the relative positional relationship of each layer. The expression "layer B on layer A" expresses the relative positional relationship between layer A and layer B, which does not necessarily require contact between layer A and layer B, and a third layer may be interposed therebetween. Similarly, the expression 'intervening C layer between layer A and layer B' does not exclude the presence of a third layer between layer A and layer C or between layer B and layer C.

1 is a view for explaining a ceramic heater 100 according to an embodiment of the present invention.

Referring to FIG. 1, a ceramic heater 100 according to an embodiment of the present invention includes a ceramic sintered body (hereinafter referred to as 130 ') formed by sintering a ceramic powder layer 130 and a ceramic sintered body 130' And a heating element 140 embedded in the heating element 140. The heating element 140 embedded in the ceramic sintered body 130 'and the ceramic sintered body 130' corresponds to a ceramic plate.

In the present invention, the ceramic sintered body 130 'is formed by forming ceramic barrier layers 110 and 150 on the upper and lower surfaces of a ceramic powder layer 130 in which a heating element 140 is inserted, (130) is formed by sintering in a carbon furnace or a carbon mold (200).

Before the sintering process, BN (Boron Nitride (BN)) is introduced into each of the ceramic barrier layers formed on the upper and lower surfaces of the ceramic powder layer 130, that is, inside any one of the first ceramic barrier layer 110 and the second ceramic barrier layer 150 The BN layer 115/155 may be interposed. The BN layer 115/155 is used as a mold release agent for suppressing the reaction between the ceramic barrier layers 110 and 150 and the ceramic sintered body 130 '. The BN layer 115/155 may be formed in the form of a coating or spray using a material including BN, or may be used in the form of a sintered body through a sintering process.

Hereinafter, a manufacturing process of the ceramic heater 100 according to an embodiment of the present invention will be described in detail with reference to the flowchart of FIG.

2 is a flowchart illustrating a manufacturing process of the ceramic heater 100 according to an embodiment of the present invention.

Referring to FIG. 2, first and second ceramic barrier layers 110 and 150 are stacked on top and bottom surfaces of a ceramic powder layer 130 in which a heating element 140 is inserted (S110). In the present invention, the laminated structure and the components constituting the laminated structure can be manufactured by various methods.

For example, the first and / or second ceramic barrier layers 110 and 150 may be applied in a mold or sprayed by a spray method, and may also be provided in the form of a molded body or a sintered body. The first and / or second ceramic barrier layers 110 and 150 are preferably provided in the form of a dense sintered body. The first and / or the second ceramic barrier layers 110 and 150 of dense sintered bodies having high brittleness and no plastic deformation can effectively block the inflow of carbon source from the outside.

A first ceramic barrier layer 110 is provided and then a ceramic powder layer 130 in which a heating element 140 is buried is formed on the first ceramic barrier layer 110. At this time, the ceramic powder layer 130 may be laminated in various ways. For example, a first ceramic powder layer is formed as a part of the ceramic powder layer 130, a heating element 140 is disposed on the first ceramic powder layer, and then a first ceramic powder layer on which the heating element 140 is disposed The ceramic powder layer 130 may be formed by covering the second ceramic powder layer. At this time, the first ceramic powder layer may be provided in the form of a molded body which can be pressed under a predetermined pressure to maintain its shape. Of course, the entire ceramic powder layer 130 may be provided in the form of a pressed molded body. A second ceramic barrier layer 150 is deposited on the ceramic powder layer 130.

Between each of the ceramic barrier layers formed on the upper and lower surfaces of the ceramic powder layer 130, that is, either one of the first ceramic barrier layer 110 and the second ceramic barrier layer 150 and the ceramic powder layer 130, As the inert layer for the role, a material including BN (Boron Nitride) may be applied or sprayed or a BN layer 115/155 in the form of a sintered body may be formed.

Since the heat generating body 140 generates heat during use as a heater, the heat generating body 140 is buried in the ceramic powder layer 130 having excellent heat resistance and excellent heat transfer characteristics. The heating element 140 may be made of a conductive material and may be formed of a metal such as tungsten (W), molybdenum (Mo), silver (Ag), nickel (Ni), gold (Au), niobium (Nb) And the like can be formed as a resistance heating element having an appropriate resistance value.

Ceramic powder layer 130 is, for _{example, Al 2 O 3, Y 2} O 3, Al 2 O 3 / Y 2 O 3, ZrO 2, AlC (Autoclaved lightweight concrete), TiN, AlN, TiC, MgO, CaO , CeO ₂ , TiO ₂ , BxCy, BN, SiO 2, SiC, YAG, Mullite, AlF 3 and the like, or a combination of these.

As described above, the heating element 140 inserted in the ceramic powder layer 130 reacts with the surrounding carbon during the sintering process to form carbide in the heating element 140, thereby increasing the resistance and causing temperature unevenness on the heating surface .

However, in the present invention, the ceramic barrier layers 110/150 are formed on and under the ceramic powder layer 130 before sintering. Carbon existing in the ceramic powder layer 130 is insignificant, and the main cause of carbide formation in the heating element 140 is mostly carbon introduced from the outside.

The first ceramic barrier layer 110 covering the lower surface of the ceramic powder layer 130 and the second ceramic barrier layer 150 covering the upper surface of the ceramic powder layer 130 are formed on the surface of the heat generating element 140 during the sintering process, It is possible to suppress the generation of carbide due to the reaction with the carbon introduced from the outside.

The first ceramic barrier layer 110 and the second ceramic barrier layer 150 may include the same material as the ceramic powder layer 130. However, since the above-mentioned ceramic material has low reactivity with carbon, it is preferable to add a predetermined amount of rare earth oxide so as to be able to react with carbon. For example, the first ceramic barrier layer 110 and the second ceramic barrier layer 150 may include nitrides such as the ceramic powder layer 130 and include 1-10 wt% (wt%) of rare earth oxides desirable. As the rare earth oxide is for example a variety of rare earth oxide such as _{LaAlO 3, La 2 O 3,} Y 2 O 3, LaAl 3 O 6 it can be used.

After forming a molded body having a laminated structure of a sandwich structure in which a ceramic powder layer 130 in which a heating element 140 is embedded is sandwiched between the first and second ceramic barrier layers 110 and 150, Similarly, the sintering process is performed in the carbon furnace or the carbon mold 200 so that the ceramic powder layer 130 becomes the ceramic sintered body (S120).

The sintering process may be performed by heating the carbon furnace 200 or the carbon mold 200 to a predetermined temperature (for example, 1500 to 2500 ° C) at which the ceramic is not decomposed and holding the carbon furnace 200 for a predetermined time (for example, 10 hours or less). The sintering process is preferably performed in a non-oxidizing atmosphere such as a vacuum or N ₂ atmosphere. Also, the sintering process can be performed by a conventional hot press sintering process.

After the sintering process, the ceramic barrier layers 110 and 150 (including the BN layers 115 and 155) are removed to remove the ceramic powder layer 130 from the sintered ceramic sintered body 130 'and the ceramic sintered body 130 A ceramic plate for a ceramic heater 100 including a heating element 140 embedded in the ceramic plate 100 is obtained (S130). At this time, the ceramic barrier layers 110 and 150 can be easily separated from the ceramic powder layer 130 due to the presence of the inert layer.

The removed ceramic barrier layers 110 and 150 can then be reused as a ceramic barrier layer of a new ceramic heater. For example, the ceramic barrier layer 110/150 may be reused after being used more than once in the sintering process, and the number of times of use may be reused within a total of 10 times.

The heating element 140 buried in the ceramic sintered body generates heat according to resistance characteristics by using electric power (for example, RF (Radio Frequency) power) supplied from the outside through an electrode (not shown). One surface of the ceramic plate is a heating surface for heating the object, and may be a surface for placing the object or for applying heat on the object. An electrode (not shown) for supplying power to the heating element 140 through the other surface of the ceramic plate may be coupled.

The ceramic heater 100 including the ceramic plate can be used for heat-treating various objects of a heat treatment target such as a semiconductor wafer, a glass substrate, and a flexible substrate at a predetermined heating temperature. For the semiconductor wafer processing, the ceramic heater may be used in combination with the function of the electrostatic chuck.

FIG. 3 is a graph for comparing resistance change rates of the conventional ceramic heater and the ceramic heater 100 according to an embodiment of the present invention.

3 shows the case where the metal dummy layer is used (Comparative Example # 2) and the ceramic barrier layers 110 and 150 of the present invention (Comparative Example # 1) when the sintering process is performed without the dummy layer or the barrier layer (Examples # 1 to # 6), the number of times of use of the ceramic barrier layer, the rare earth content (wt%), and the like. Here, AlN was used for the ceramic barrier layer 110/150, and Y ₂ O ₃ was added as a rare earth oxide capable of reacting with carbon.

As shown in FIG. 3, when the content of the rare earth oxide exceeds 10 wt%, the appearance of the liquid phase in the ceramic barrier layer 110/150 during sintering becomes high, so that the product reacts with the carbon furnace or the carbon mold 200, This became difficult. Therefore, it is preferable to add a rare earth oxide to the ceramic barrier layer 110/150 in an amount of 10 wt% or less. If the rare earth oxide content is less than 1 wt%, the effect of suppressing the carbonization of the heating element may become insignificant.

It was also confirmed that the rate of change in resistance of the heating element 140 was not so large depending on the carbon content contained in the ceramic powder layer 130 as the raw material.

The ceramic barrier layer 110/150 can be reused for sintering other ceramic powder compacts. However, as shown in FIG. 3, when the number of times of use is 10 or more, the resistance change rate of the heating element 140 starts to increase Respectively.

When the present invention is compared with the case where the conventional dummy layer or barrier layer (Comparative Example # 1) is used and the case where the metal dummy layer is used as in the prior art (Comparative Example # 2), the ceramic barrier layers 110, It can be confirmed that the temperature deviation of each position of the ceramic plate heating surface is significantly improved when the ceramic heater 100 is used by applying electric power in the case of Embodiments # 1, # 2, # 5 and # , It can be seen that the resistance change rate of the hot zone, which is caused by the increase in resistance due to the generation of localized carbides, is lower than that of the prior art, when manufactured according to the embodiment of the present invention.

In the prior art, a metal dummy member (e.g., 4A, 5A, 6A group metal) is used to reduce the resistance of the heating element, and the resistance of the heating element can be lowered to some extent by shielding the carbon inflow from the outside. That is, the metal dummy member reduces the carbon that flows in from the outside, thereby reducing the carbonization area of the heating body, thereby reducing the resistance of the heating body to some extent. However, such a conventional technique can lower the overall resistance change of the heating element, but can not prevent the resistance change of the heating element locally unevenly. In addition, the conventional metal dummy member is used as a one-time type, reacts with carbon, and is carbonized rapidly during sintering to exhibit brittleness, thereby causing cracks in use, and the generated crack acts as an inflow path of carbon source . Further, the carbonization reaction of the metal pile also causes damage to the product surface. Therefore, the powder sintered body has to be made thicker than necessary to remove the damaged portion.

However, according to the ceramic heater 100 of the present invention as described above, the ceramic barrier layer 110/150 is formed above and below the ceramic powder compact for embedding the heating element, and the BN layer 115/155 for the release agent is further provided The overall resistance change of the heating body 140 can be lowered in the sintering process, and the local resistance change ratio can also be improved. That is, by using the ceramic barrier layer 110/150 in the present invention, the formation of brittle carbides and the occurrence of cracks in the sintering process can be remarkably reduced. Therefore, by using the ceramic barrier layer 110/150 of the present invention, the amount of carbon flowing into the ceramic block layer 110 is significantly reduced, thereby reducing the overall resistance change of the heating body 140 during the sintering process and improving the local resistance change ratio. Further, the BN layer 115/155 for the role of a mold release agent is more advantageous for blocking carbon from the ceramic barrier layer 110/150 by preventing the reaction with the ceramic powder layer 130, and the ceramic barrier layer 110 / 150). ≪ / RTI >

In addition, when a part of the heating body 140 which is locally carbonized is operated as a heater after sintering, the amount of heat generated at the corresponding part can be increased to form a hot zone around the area. According to the present invention, the possibility of an increase in the resistance of the heating element at a local position such as a hot zone is blocked, so that the temperature deviation per position of the heating surface of the object such as a wafer is remarkably reduced, and the temperature uniformity of the heating surface can be increased. Further, in the prior art, there is a problem that a ceramic powder sintered body must be made thicker than necessary in order to suppress the occurrence of scratches on the product surface. However, in the present invention, by using the ceramic block layer 110/150 having low reactivity, The machining allowance of the ceramic powder compact can be reduced and the amount of the ceramic powder compact used can be reduced.

As described above, the present invention has been described with reference to particular embodiments, such as specific elements, and specific embodiments and drawings. However, it should be understood that the present invention is not limited to the above- Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the essential characteristics of the invention. Therefore, the spirit of the present invention should not be construed as being limited to the embodiments described, and all technical ideas which are equivalent to or equivalent to the claims of the present invention are included in the scope of the present invention .

The ceramic powder layer (130)
The heating element 140,
The ceramic barrier layers 110 and 150,
BN (Boron Nitride) layers 115 and 155,

Claims (11)

Forming a laminate structure of a sandwich structure in which a ceramic powder layer embedded with a heating element is sandwiched between the first ceramic barrier layer and the second ceramic barrier layer; And
Sintering the formed article of the laminated structure
Wherein the ceramic heater is made of a ceramic material. The method according to claim 1,
In the forming step of the laminated structure,
Providing the first ceramic barrier layer;
Providing the ceramic powder layer on which the heating element is embedded on the first ceramic barrier layer; And
Providing the second ceramic barrier layer on the ceramic powder layer
The method of manufacturing a ceramic heater according to claim 1, 3. The method of claim 2,
The step of providing the ceramic powder layer comprises:
Providing a first ceramic powder layer;
Disposing the heating element on the first ceramic powder layer; And
Providing a second ceramic powder layer on the first ceramic powder layer on which the heating element is disposed
The method of manufacturing a ceramic heater according to claim 1, The method of claim 3,
Wherein the first ceramic powder layer is a molding in the step of providing the first ceramic powder layer. The method of claim 3,
After the step of providing the second ceramic powder layer,
A step of press-molding the first ceramic powder layer, the heating element and the second ceramic powder layer
Further comprising a step of heating the ceramic heater. The method according to claim 1,
Wherein an inert layer containing boron nitride (BN) is interposed between each of the first and second ceramic barrier layers and the ceramic powder layer. The method according to claim 1,
Wherein the first and second ceramic barrier layers comprise rare earth oxides. 8. The method of claim 7,
Wherein the first and second ceramic barrier layers comprise a nitride and a rare earth oxide,
Wherein the rare earth oxide is 10 wt% or less of the ceramic barrier layer. The method according to claim 1,
Wherein the first and second ceramic barrier layers are sintered bodies. The method according to claim 1,
Wherein the first and second ceramic barrier layers reduce local generation of carbide due to reaction with carbon flowing from the outside in the heating element during the sintering process. A ceramic sintered body and a heating element buried in the ceramic sintered body,
The ceramic sintered body may be,
Wherein a ceramic body having a laminate structure of a sandwich structure in which a ceramic powder layer embedded with a heating element is sandwiched between the first ceramic barrier layer and the second ceramic barrier layer is formed by sintering the ceramic powder layer, .

Images