KR20120102867A - Method for repairing a heating plate of a ceramic heater - Google Patents

Abstract

PURPOSE: A heating plate repair method of a ceramic heater is provided to prevent the deformation of a heating plate by performing sealing and welding using Y2O3-Al2O3-SiO2 mixture having a low melting point. CONSTITUTION: The upper side of a heating plate(10) is grinded. A pocket(14) is formed by partly cutting a damaged portion of the grinded upper side of the heating plate. A sealant(20) is bonded to the pocket. A ceramic plate(30) of same material as the heating plate is bonded to the heating plate using adhesive. The upper side of the ceramic plate is molded. At least one between the sealant and the adhesive comprises a mixture of Y2O3, Al2O3, and SiO2. [Reference numerals] (AA) Grinding process; (BB) Pocket formation process; (CC) Sealing process; (DD) Bonding process; (EE) Molding process

Description

Repair method of heating plate of ceramic heater {METHOD FOR REPAIRING A HEATING PLATE OF A CERAMIC HEATER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating plate repairing method of a ceramic heater, and more particularly, to a heating plate repairing method of a ceramic heater used for heating a substrate in a manufacturing process of a semiconductor device or a display device.

In general, ceramic heaters are used for high temperature processing such as chemical vapor deposition (CVD) or surface modification in the manufacturing process of semiconductor devices or display devices.

The ceramic heater is composed of a disk-shaped heating plate on which a substrate is placed and a cylindrical shaft coupled perpendicularly to the lower surface of the heating plate. A heating element, for example a resistance heating element, is embedded in the heating plate, and a rod for supplying power is provided in the shaft longitudinal direction.

Looking in more detail with reference to Figure 1, the bottom of the heating plate is provided with a terminal connected to the embedded heating element or RF electrode, the upper end of the rod is connected to this terminal. The rod is made of an insulating material, and a wire is embedded in the rod, so that the wire is connected to a heater or an RF electrode when connecting the rod and the terminal.

The heating plate of the ceramic heater, for example, is not only placed in an erosive atmosphere in the CVD process but also the damage of the upper part due to the physical impact of the process of raising and lowering the substrate, and also caused by chipping, whitening of the heating plate, and the like. A problem arises.

In addition, the ceramic heater is repeatedly heated and cooled at a temperature of about 350 to 550 ° C., and due to the thermal expansion difference between the rod (mainly in the longitudinal direction) and the ceramic during the repeated heating / cooling process, as shown in FIG. 2. This, cracks are generated on the heating plate. These cracks are difficult to recover by simple surface grinding.

If damage occurs to the heating plate of the ceramic heater as described above, at present the expensive heating plate itself is replaced and discarded. It would be nice if the damaged heating plate could be repaired and reused, but so far no repair method has been introduced.

As a well-known technique which can be referred to in connection with the present invention, there is Japanese Patent Laid-Open No. 2009-0104122.

The present invention provides a heating plate repair method and a ceramic heater reformed by such a repair method to be reformed and reused instead of replacing it, if a crack or the like occurs on the heating plate of the ceramic heater as described above. It aims to provide.

The heating plate repair method of such a ceramic heater should not cause a change in the coefficient of thermal expansion local to the heating plate due to the repair, and the repaired heating plate should be able to guarantee the overall crack.

On the other hand, if the heating plate repair is included in the bonding process, the deformation of the heating plate should not occur in the bonding process.

Heating plate repair method of a ceramic heater according to the present invention for achieving the above object, the process of grinding the entire upper surface of the heating plate; Forming a pocket by partially cutting a damaged part of the upper surface of the ground heating plate; Fusion sealing the sealing material to the pocket; Bonding a ceramic plate of the same material as the heating plate onto the sealed heating plate using a bonding material; And forming a top surface of the ceramic plate.

According to the present invention, at least one of the sealing material and the bonding material may include a mixture of Y ₂ O ₃ , Al ₂ O ₃ and SiO ₂ .

In addition, the mixture may include Y ₂ O ₃ 22 ~ 40wt%, Al ₂ O ₃ 18 ~ 40wt% and SiO ₂ 25 ~ 60wt%.

In addition, at least one of the sealing material and the bonding material may further include a ceramic of the same material as the heating plate in addition to the mixture.

In addition, more ceramic filler may be contained in the sealing material than the bonding material.

In addition, the heating plate is made of aluminum nitride, the sealing material may include an 8 to 15% aluminum nitride filler relative to the total weight of the mixture.

In addition, the heating plate is made of aluminum nitride, the bonding material may include an aluminum nitride filler of 3 to 5% of the total weight of the mixture.

In addition, the bonding material may be previously applied to the ceramic plate with a thickness of 30 ~ 40㎛.

In addition, each joint surface of the heating plate and the ceramic plate may have a surface roughness (Ra) of 0.1 ~ 0.3㎛.

On the other hand, the ceramic heater according to the present invention, the heating plate of the ceramic material is installed heating element; A hollow ceramic shaft vertically coupled to the bottom surface of the heating plate; And a power supply member connected to the heating element through the shaft. And the heating plate here is a heating plate repaired using the repair method described above.

According to the present invention as described above, if damage such as cracks in the upper portion of the heating plate during the use of the ceramic heater can be reused through repair without replacing the entire surface of the heating plate and discarded.

In addition, the heating plate repaired by the repair method according to the present invention, the ceramic plate of the same material is bonded to the entire upper surface of the heating plate is possible to crack the substrate mounted on the heating plate.

In addition, the heating plate repaired by the repair method according to the present invention is very similar to the original heating plate that the thermal expansion behavior and the thermal conductivity characteristics according to the temperature at the junction is not repaired, so that during the heating / cooling process within the process temperature range The overall heat distribution of the top surface is fairly uniform and does not cause quality problems due to reuse.

In addition, according to the present invention, the sealing material and the bonding material using the Y ₂ O ₃ -Al ₂ O ₃ -SiO ₂ mixture have very similar thermal expansion behavior to the heating plate or shaft of the ceramic heater, and the heating plate due to the difference in thermal expansion during use after repair It does not cause a defect.

In addition, according to the present invention, since the sealing and bonding is made by the Y ₂ O ₃ -Al ₂ O ₃ -SiO ₂ mixture having a low melting point, the deformation of the heating plate is prevented during the repair process, bonding through a conventional sintering process Because of this, Hot Pressing (Hot Pressing), Hot Isostatic Pressing (GPS), Gas Pressure Sintering (GPS), etc. are not required.

1 is a view showing the power supply members installed on the heating plate lower surface of the ceramic heater,
2 is a view showing a crack generated on the heating plate of the ceramic heater,
3 is a view showing a heating plate repair process according to an embodiment of the present invention,
Figure 4 is a three-phase component system showing the composition of the sealing material and the bonding material according to an embodiment of the present invention,
5 is a view showing a test result of the structure after curing the sealing material according to the amount of the ceramic filler included in the sealing material according to an embodiment of the present invention,
6 is a view showing the thermal expansion characteristics of the sealing member and the bonding material according to an embodiment of the present invention,
Figure 7 is a SEM picture of the joint using the bonding material according to an embodiment of the present invention.
8 is a view showing a test result of the heat distribution of the repaired heating plate and the heating plate before repair according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings looks at the heating plate repair method of the ceramic heater according to a preferred embodiment of the present invention.

Referring to FIG. 3, the heating plate repairing method according to the embodiment includes an upper grinding process, a pocket forming process, a sealing process, a bonding process, and a molding process of the heating plate in which damage occurs.

3 to 8 will be described in detail with respect to each of the above process.

Grinding  fair

Referring to FIG. 3, when the crack 1 is generated in the upper portion of the heating plate 10 due to a difference in thermal expansion between the heating plate 10 and the rod, the upper surface of the heating plate 10 is ground flat.

As shown in FIG. 3, the heating plate 10 is, as one example, an RF electrode 11 at an upper portion thereof, a pattern of a heating element 12 embedded at a lower portion thereof, and an upper edge of the heating plate 10. Along the protruding jaw 13 may be provided.

Grinding of the heating plate 10 as described above is made for the entire upper surface including the protruding jaw 13 of the edge as well as the damaged area, the grinding depth (D) is buried in the upper side of the heating plate (10) The RF electrode 11 is properly selected in such a degree that no damage occurs.

Pocket forming process

The pocket is formed by partially cutting the damaged part from the upper surface of the heating plate 10 which has been subjected to the entire process.

If cracks 1 are generated from the inside of the upper portion of the heating plate 10, cracks may remain after surface grinding, and the cracks may be cut and removed from the surroundings in a rectangular, circular or other form to seal the sealing site. Pocket 14).

Sealing process

The heating plate 10 and the sealing material 20 having a similar thermal expansion behavior according to temperature are fused to the pocket 14 formed through the entire process to seal.

As an example, the sealing material 20 is a mixture of Y ₂ O ₃ -Al ₂ O ₃ -SiO ₂ composition. Referring to the Y ₂ O ₃ -Al ₂ O ₃ -SiO ₂ three-phase state diagram of FIG. 4, in this state diagram, a mixture of Y ₂ O ₃ -Al ₂ O ₃ -SiO _{2 having} a composition corresponding to near an eutectic point It is used as this sealing material 20.

More specifically, the sealing material 20 is a mixture of Y ₂ O ₃ 22 ~ 40wt%, Al ₂ O ₃ 18 ~ 40wt%, SiO ₂ 25 ~ 60wt% and includes a ceramic of the same material as the heating plate 10 do. Aluminum nitride (AlN) is typically used as a material of the ceramic heater, and the sealing material 20 includes 8 to 15% of an aluminum nitride filler based on the total weight of the mixture.

The above ceramic filler is uniformly mixed with the Y ₂ O ₃ -Al ₂ O ₃ -SiO ₂ mixture and bubbles inside when the liquid phase is formed near the process temperature of Y ₂ O ₃ -Al ₂ O ₃ -SiO ₂ . It functions to slow down the rate at which the liquid phase is formed so that it does not remain.

When the content of the aluminum nitride filler in the sealing material is less than 8%, the sealing material is transferred to the liquid phase again at the joining temperature, and internal bubbles may be generated due to volatilization. Remaining, densification is deteriorated and does not act as a sealing and a problem occurs in the withstand voltage.

The filler content in the sealing material 20 should be at least about 5% more than that of the bonding material 40 and the sealing temperature is preferably set to about 50 ° C. higher than the bonding temperature. The reason for this is to prevent the sealing material 20 from being liquefied again and thereby contracted at the junction temperature.

The filler may not enter too much because the main material (Y ₂ O ₃ -Al ₂ O ₃ -SiO ₂ ) reacts and delays the time that the liquid phase is formed. In some cases, it may be necessary to properly include the main material.

5 shows some of the results of experiments performed in various ways to determine the composition of the sealing material 20 and the bonding material 40, in particular to determine the amount of ceramic filler included therein.

As shown in FIG. 5, when no filler is included (liquid temperature about 1400 ° C.), internal bubbles are generated due to liquid volatilization, and 5% filler (liquid temperature about 1425 ° C.) and 15% (liquid temperature about 1500 ° C.) Dense tissue without internal bubbles is obtained, and internal bubbles remain in case of 18% of filler (liquid temperature above 1500 ℃).

In consideration of the sealing temperature and the bonding temperature in addition to the results of the various experiments as described above, it is possible to determine the content of the filler contained in the sealing material 20 and the bonding material 40, for example, based on the relatively stable liquid at 1450 ℃ The filler content of (20) targets around 5%, and the filler content of the bonding material 40 targets 15%, and determines each filler content.

In the process of determining the filler content, the filler content in the sealing material 20 should be at least about 5% or more higher than that of the bonding material 40 and the sealing temperature should be set to about 50 ° C. higher than the bonding temperature. The optimal filler content is 8-15% for the sealing material 20, and 3-5% for the bonding material 40 as shown below.

On the other hand, fusion of the sealing material is applied to the pocket 14 formed through the entire process to paste the sealing plate 10 and the sealing material 20 similar in thermal expansion behavior to temperature, and then dried and dried at approximately 600 ℃ or less After degreasing it is carried out in a manner of fusion in the range of 1450 ~ 1500 ℃.

Bonding process

In the previous process, the ceramic plate 30 of the same material as the heating plate 10 is bonded to the heating plate 10 on which the pocket 14 is sealed using the bonding material 40.

For example, when the heating plate 10 is made of aluminum nitride, the ceramic plate 30 made of aluminum nitride is bonded. The ceramic plate 30 has a size of the heating plate 10, the bonding material 40 for bonding to the heating plate 10 is applied to the lower surface.

As the bonding material 40, a mixture of Y ₂ O ₃ -Al ₂ O ₃ -SiO ₂ having the same composition range (near the process point) as the sealing material described above is used as an example. More specifically, the bonding material 40 is a mixture of Y ₂ O ₃ 22-40 wt%, Al ₂ O ₃ 18-40 wt%, SiO ₂ 25-60 wt% and the heating plate 10 as in the sealing material 20 here. Aluminum nitride which is a material is included as a filler.

The bonding material 40 contains at least approximately 5% less aluminum nitride filler than in the sealing material 20. As an example, since the sealing material 20 includes 8 to 15% of aluminum nitride filler relative to the total weight of the Y ₂ O ₃ -Al ₂ O ₃ -SiO ₂ mixture, the bonding material 40 has less than 3 to 5% (Y _2). Relative to the total weight of the O ₃ -Al ₂ O ₃ -SiO ₂ mixture.

When the content of the aluminum nitride filler is less than 3%, internal bubbles may be generated due to some liquid volatilization at the joining temperature, and when added in excess of 5%, the filler may be excessively contained to significantly reduce the bonding strength. The reason why less filler is used than in the sealing material 20 is to bond at a lower temperature than the sealing material 20 and to obtain excellent bonding force.

On the other hand, the bonding of the heating plate 10 and the ceramic plate 30 using the bonding material 40, the surface (top surface) in which the cracks of the heating plate 10 is sealed and the ceramic plate (preprinted) the bonding material 40 ( After the surface (lower surface) of 30) is faced, it may be made by heating at a high temperature.

The thickness of the bonding material applied to the ceramic plate 30 is preferably 30 ~ 40㎛. If the thickness is less than 30 μm, a continuous bonding layer may not be formed and bubbles may be formed therein, which adversely affects bonding strength. In addition, when it is thicker than 40 μm, the thickness of the bonding layer becomes thick, and the thermal conductivity emitted from the heating plate 10 is lowered, resulting in poor temperature uniformity on the surface (upper surface) of the ceramic plate 30.

In addition, it is preferable that the mutual joining surface of the heating plate 10 and the ceramic plate 30 is 0.1-0.3 surface roughness (Ra, micrometer). If the surface roughness is less than 0.1, there is a problem in that the coating of the bonding material 40 is not fixed due to sliding, and if the surface roughness is larger than 0.3, there is a possibility that a void is generated in the bonding layer and there may be a problem in insulation resistance.

Bonding firing temperature of the heating plate 10 and the ceramic plate 30 is preferably 1400 ~ 1450 ℃, to prevent distortion when bonding the plate by pressing the weight produced larger than the material according to the area of the plate It is good.

6 is a heating plate of the aluminum nitride ceramic heater for thermal expansion behavior according to the temperature of the Y ₂ O ₃ -Al ₂ O ₃ -SiO ₂ mixture used as the sealing material 20 and the bonding material 40 according to the embodiment described above (10) and a graph showing an example of one of the results of the comparative experiment with Shaft.

As shown in FIG. 6, the bonding material 40 using the Y ₂ O ₃ -Al ₂ O ₃ -SiO ₂ mixture according to the embodiment has almost the same thermal expansion characteristics as the heating plate 10 or the shaft in the use temperature range of the ceramic heater. Appeared to be visible. Although not shown, the sealing material 20 according to the embodiment was also not significantly different from the result of FIG. 6.

The bonding material 40 evaluated in FIG. 6 includes 3% AlN filler, and has a high thermal shock resistance due to thermal expansion / shrinkage at elevated temperature / cooling because the thermal expansion behavior is similar.

As a result of the thermal shock test of the sample bonded with the bonding material 40 according to the embodiment, the bonding material after quenching from the temperature of 300 ° C. to 20 ° C. (of course, in the actual repair process) Although cracks occurred on the surface as a whole, it was confirmed that the joint was stable without separation.

7 is an electron micrograph (SEM) photograph of the vicinity of a boundary of a specimen in which plates of aluminum nitride are bonded to each other by using the bonding material 40 according to the embodiment. As shown in FIG. 7, the bonding material layer was almost continuously in interface with the aluminum nitride plates at a thickness of about 20 μm.

Due to the properties of the bonding interface as described above, the bonding layer using the bonding material 40 according to the embodiment is excellent in thermal shock resistance to thermal expansion / shrinkage at the time of heating / cooling, the ceramic plate 30 in the heating plate 10 As the thermal conductivity through the bonding layer to the furnace is 95% or more, temperature uniformity at the surface can be obtained.

Molding process

In the previous step, the upper surface of the heating plate 10 to which the ceramic plate 30 is bonded (that is, the upper surface of the ceramic plate) is molded, and the upper shape of the original heating plate 10 having the jaws 13 or the like protruding at the edges. Make it.

Such molding may be performed by machining the upper surface of the ceramic plate 30 using a machining center or a cylindrical polishing machine in a concave shape, and using sandblasting on the upper surface of the processed ceramic plate 30. Embossing and ribs of a certain size can be formed.

On the other hand, the ceramic plate 30 may be partially molded in advance before bonding to the heating plate 10. However, even in this case, since some deformation occurs in the bonding process, it is necessary to mold to remove such deformation. The present molding process needs to be understood as a process including molding for removing such deformation.

8 is a view showing one of the results of comparing and inspecting the heat distribution of the repaired heating plate and the repaired heating plate through a series of processes described above, and as shown in this figure, the temperature uniformity of the surface (ΔT, MAX-MIN). ) Improved the temperature uniformity by more than about 40% from 12.8 ℃ before repair to about 7.8 ℃ after repair.

The above results show that the temperature uniformity decreases due to contamination and whitening of the surface before repairing, but forms a new surface layer after repairing. In particular, the thickness of the bonding layer is thin and continuously formed. Since the thermal conductivity through the bonding layer from the heating plate 10 to the ceramic plate 30 is also very good, it seems that the temperature uniformity at the surface can be maintained.

In addition, the above heat distribution results show that the ceramic heater repaired through the process according to the present invention can be used normally in the field without any problem.

The present invention needs to be understood that a heating element for heating the substrate to a constant temperature is applicable to a ceramic heater embedded in or installed somewhere in a heating plate. Recently, the development of a ceramic heater having an electrostatic chuck (esc) function is active, it can be applied to such a ceramic heater.

In the above embodiment, only the aluminum nitride, which is typically used as a material of the ceramic heater, has been described, but it may be applicable to other ceramics. However, it may be necessary to develop other sealing and bonding materials to replace the Y ₂ O ₃ -Al ₂ O ₃ -SiO ₂ glass used as the sealing and bonding materials in the above embodiment.

Although specific embodiments of the present invention have been shown and described, the present invention may be variously modified and changed without departing from the spirit of the invention as set forth in the claims below, and this is in the technical field of the present invention. It should be understood that it is self-evident to those of ordinary knowledge.

10: heating plate 11: RF electrode
12: heating element 14: pocket
20: sealing material 30: ceramic plate
40: bonding material

Claims (10)

Grinding the entire upper surface of the heating plate;
Forming a pocket by partially cutting a damaged part of the upper surface of the ground heating plate;
Fusion sealing the sealing material to the pocket;
Bonding a ceramic plate of the same material as the heating plate onto the sealed heating plate using a bonding material; And
Forming a top surface of the ceramic plate; heating plate repair method of a ceramic heater comprising a. The method of claim 1, wherein at least one of the sealing material and the bonding material comprises a mixture of Y ₂ O ₃ , Al ₂ O ₃ and SiO ₂ heating plate repair method of a ceramic heater. The method of claim 2, wherein the mixture is Y ₂ O ₃ 22 ~ 40wt%, Al ₂ O ₃ 18 ~ 40wt% and SiO ₂ 25 ~ 60wt% heating plate repair method of a ceramic heater, characterized in that. The heating plate repair method of claim 2, wherein at least one of the sealing member and the bonding member further includes a ceramic having the same material as the heating plate as a filler in addition to the mixture. The method of repairing a heating plate of a ceramic heater according to claim 4, wherein more ceramic filler is contained in the sealing material than the bonding material. The heating plate repair method of claim 4, wherein the heating plate is made of aluminum nitride, and the sealing material includes 8 to 15% of an aluminum nitride filler based on the total weight of the mixture. The heating plate repair method of claim 4, wherein the heating plate is made of aluminum nitride, and the bonding material includes 3 to 5% of an aluminum nitride filler based on the total weight of the mixture. The method of claim 2, wherein the bonding material is a heating plate repair method of the ceramic heater, characterized in that the pre-coated to the ceramic plate with a thickness of 30 ~ 40㎛. The repairing method of a heating plate of a ceramic heater according to claim 2, wherein each joining surface of the heating plate and the ceramic plate has a surface roughness Ra of 0.1 to 0.3 µm. A heating plate of ceramic material provided with a heating element;
A hollow ceramic shaft vertically coupled to the bottom surface of the heating plate; And
And a power supply member connected to a heating element through the shaft.
The heating plate is a ceramic heater, characterized in that the heating plate repaired through the process of any one of claims 1 to 9.

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