JP4522963B2 - Heating device - Google Patents

Description

  The present invention relates to a heating device.

  In a semiconductor device manufacturing process, heat treatment is performed to form an oxide film or the like on a wafer using a semiconductor manufacturing apparatus. In this semiconductor manufacturing apparatus, a heating apparatus for heating a wafer includes a ceramic heater in which a linear resistance heating element is embedded in a disk-shaped ceramic substrate having a heating surface on which a wafer as an object to be heated is set. There is. One or a plurality of the resistance heating elements are embedded in a wiring pattern parallel to the heating surface of the ceramic substrate, and the heating surface is heated by applying a voltage to both ends of the wire.

  Also, in this ceramic heater, a disc-shaped high-frequency electrode capable of applying a high frequency is embedded in the vicinity of the heating surface, and high-frequency plasma is generated in the space near the object to be heated set on the heating surface between the counter electrode. Some can generate or apply a bias electrode. This high frequency plasma is used for forming a film by plasma CVD.

  As a material used for the ceramic heater, a material having a sufficiently high electric resistivity or an insulating property with respect to the resistance heating element at an operating temperature for heating the object to be processed is used. This is because when the material of the ceramic substrate is conductive, a part of the current supplied to heat the resistance heating element flows through the ceramic and generates heat in a region other than the resistance heating element, or This is because the desired current does not flow through the resistance heating element, and soaking is significantly impaired.

  For this reason, aluminum nitride is frequently used as the base material of the ceramic heater. Aluminum nitride has good heat resistance and corrosion resistance, high thermal conductivity, and high resistance.

  With respect to a sintered body using aluminum nitride used in such a ceramic heater, there is an aluminum nitride sintered body mixed with carbon fiber in order to obtain a volume resistivity suitable as an electrostatic chuck (Patent Document 1). .

Further, regarding a susceptor having a low volume resistivity, a ceramic susceptor has a laminated structure of a surface layer having a mounting surface on which a non-processed object is placed and a support layer, and this surface layer is entirely covered with a support layer. Some have low volume resistivity (Patent Document 2).
JP-A-2005-14765 JP 2002-134590 A

  When generating plasma on the surface of the object to be heated set on the heating surface of the ceramic heater, it is important to generate the plasma so that it is uniformly distributed on the surface of the object to be heated. This is because, when the distribution of plasma on the surface of the object to be heated is non-uniform, for example, when a film is formed on the surface of the wafer by the plasma CVD method, the in-plane variation in the film thickness of the film occurs. This is because the product characteristics may vary.

  However, in the conventional ceramic heater, there is a case where the plasma state is different between the central portion and the outer peripheral portion of the wafer, and the plasma distribution is uneven in the radial direction. For this reason, the film thickness of the film formed on the surface of the wafer by the plasma CVD method sometimes varies between the central portion and the outer peripheral portion of the wafer.

  Such non-uniformity of the plasma distribution is caused by the fact that a convex part having an upper surface with a diameter slightly smaller than the diameter of the wafer is formed at the center of the heating surface among ceramic heaters. There is a possibility that this may occur in the case of a ceramic heater for heating a wafer.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a heating apparatus that can uniformly produce a product with good characteristics by making the plasma distribution uniform at the center and the periphery of an object to be heated.

  In order to achieve the above object, a heating device of the present invention comprises an insulating ceramic substrate having a heating surface for heating an object to be heated, a heating element disposed on the insulating ceramic substrate, and the insulating ceramic substrate. And a conductive member connected to the low-resistance ceramic member, and a low-resistance ceramic member provided in parallel with the heating surface.

  According to the heating device of the present invention, the distribution of plasma generated on the object to be heated can be made uniform.

  Embodiments of the heating device of the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an embodiment of a heating device according to the present invention. In the drawings described below, in order to facilitate understanding of each component of the heating device, each component has a dimensional ratio different from that of the actual heating device. Therefore, the heating device according to the present invention is not limited to the dimensional ratio of the heating device illustrated in the drawings.

The heating apparatus of the present embodiment shown in FIG. 1 has a disk-shaped insulating ceramic substrate 10. The insulating ceramic substrate 10 includes an upper ceramic member 11 and a lower ceramic member 12, and the upper ceramic member 11 and the lower ceramic member 12 are made of, for example, aluminum nitride (AlN) ceramics. Moreover, it has high resistance or insulation, and has a volume resistivity of, for example, 10 ⁸ Ω · cm or more, similar to the resistivity of ordinary ceramics.

  The upper ceramic member 11 of the insulating ceramic substrate 10 shown in FIG. 1 is formed in a central portion on the side where the wafer W, which is an object to be heated, is placed with a diameter slightly smaller than the diameter of the wafer W. Yes. That is, FIG. 1 shows an example of an insulating ceramic substrate 10 in which a step is formed on the heating surface. The upper ceramic member 11 engages with the peripheral portion of the upper ceramic member 11 when the wafer W is placed on the insulating ceramic substrate 10 or when the wafer W is removed from the insulating ceramic substrate 10. This is to make it possible to use a jig (not shown) for carrying W. The wafer W is placed on the flat upper surface of the upper ceramic member 11 of the insulating ceramic substrate 10 shown in FIG. 1 and heated.

  A resistance heating element 13 is embedded in the lower ceramic member 12. An electrode rod 14 connected to the resistance heating element 13 is connected to the end of the resistance heating element 13. The electrode rod 14 is connected to an external power source (not shown).

  A high-frequency electrode 15 is embedded below the upper ceramic member 11 and parallel to the upper surface of the upper ceramic member 11. As the high-frequency electrode 15, for example, a planar electrode having a perforated pattern made of a bulk material of a metal such as Mo or W, more preferably a mesh-shaped (wire mesh-shaped) electrode can be used. Plasma P is generated between the high-frequency electrode 15 and the counter electrode 20 disposed on the opposite side of the high-frequency electrode 15 across the wafer W to perform surface treatment of the wafer W, for example, film formation. In order to generate the plasma P satisfactorily, the high-frequency electrode 15 is desirably embedded to a depth of about several millimeters from the surface of the upper ceramic member 11 on which the wafer W is placed. It is also embedded to protect the high frequency electrode from a corrosive atmosphere. Therefore, the high frequency electrode 15 is embedded in the upper ceramic member 11, and the diameter of the high frequency electrode 15 is smaller than the diameter of the upper ceramic member 11.

  A plate-like low-resistance ceramic member 16 is provided in parallel with the heating surface in contact with the back surface of the high-frequency electrode 15. The low resistance ceramic member 16 has the same diameter as the lower ceramic member 12 and is larger than the diameter of the wafer W. An electrode rod 17 is connected to the high-frequency electrode 15 through the low-resistance ceramic member 16, and high-frequency plasma power is supplied from a power source (not shown) to the high-frequency electrode 15 and the low-resistance ceramic member 16 in contact with the high-frequency electrode 15. It is possible.

  The heating device of the present embodiment is provided with the plate-like low-resistance ceramic member 16 as described above, and the low-resistance ceramic member 16 is in contact with the high-frequency electrode 15. 15 integrally functions as a high-frequency electrode. Since the low resistance ceramic member 16 has the same diameter as the lower ceramic member 12 and is larger than the diameter of the wafer W, the plasma P generated between the low resistance ceramic member 16 and the counter electrode 20 is generated in the radial direction from the center of the wafer W. A uniform plasma state from the outer periphery to the outer side of the wafer W can be obtained. Therefore, the distribution of the plasma in the radial direction on the wafer W can be made uniform between the central portion and the peripheral portion.

  The material of the low resistance ceramic member 16 is a conductive material having a lower electrical resistance than the upper ceramic member 11 and the lower ceramic member 12, and for example, low resistance aluminum nitride (AlN) ceramics is used. Can do. The component composition of the low resistance aluminum nitride-based ceramics is not particularly limited. For example, aluminum nitride containing carbon fibers as disclosed in Patent Document 1 can be used. As a conventionally known low resistance aluminum nitride ceramic, aluminum nitride containing an oxide of a rare earth element such as yttrium oxide, cerium oxide, or samarium oxide can be used.

  The volume resistivity of the low-resistance ceramic member 16 is preferably as low as possible in order to function as a high-frequency electrode. For example, a material having a resistance of 1Ωcm or more and 100Ωcm or less can be used. As a material having a volume resistivity in such a numerical range, for example, there is a low resistance aluminum nitride ceramic material disclosed in Patent Document 1, which can be suitably applied in the present invention.

  From the viewpoint of acting as a high-frequency electrode, it is conceivable to use a conductive metal material instead of the low-resistance ceramic member 16. However, when a metal material is used instead of the low-resistance ceramic member 16, the metal material is exposed in the region outside the outer peripheral portion of the wafer W in the configuration as shown in FIG. Corrosion is caused by the corrosive atmosphere of the use environment, and contamination of the wafer W is caused.

  As the ceramic of the low resistance ceramic member 16, it is conceivable to use a low resistance or conductive ceramic made of a different main component from the upper ceramic member 11 and the lower ceramic member 12. However, when low resistance or conductive ceramics composed of main components different from the upper ceramic member 11 and the lower ceramic member 12 are used for the low resistance ceramic member 16, the low resistance ceramic member 16 and the upper ceramic member 11 are used. Further, due to the difference in thermal expansion coefficient between the lower ceramic member 12 and the lower ceramic member 12, internal stress may remain inside the upper ceramic member 11 and the lower ceramic member 12 and may be damaged. On the other hand, when the low resistance ceramic member 16 is a ceramic having a main component in common with the upper ceramic member 11 and the lower ceramic member 12 of the insulating ceramic base 10, the difference in thermal expansion coefficient is slight, Almost no stress is generated, resulting in excellent durability. Further, there is almost no difference in thermal conductivity, and high-frequency plasma can be efficiently generated without impairing the thermal uniformity of the insulating ceramic substrate 10. Therefore, it is more preferable that the low resistance ceramic member 16 is a ceramic having a main component in common with the insulating ceramic base 10.

Figure 2 is a cross-sectional view illustrating an example of a pressurized thermal device. In FIG. 2, the same members as those in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted below.

Pressure heat system shown in FIG. 2 includes an insulating ceramic base 30. The insulating ceramic substrate 30 includes an upper ceramic member 31 and a lower ceramic member 32. The upper ceramic member 31 and the lower ceramic member 32 are made of, for example, aluminum nitride (AlN) ceramics. The upper surface of the upper ceramic member 11 is a heating surface, and the wafer W is placed at the center of the heating surface. Further, in the vicinity of the heating surface, a plate-like low resistance ceramic member 16 is embedded in parallel with the heating surface. The low resistance ceramic member 16 has the same diameter as the upper ceramic member 31 and the lower ceramic member 32 and is larger than the diameter of the wafer W. An electrode rod 17 is connected to the low resistance ceramic member 16 so that high frequency plasma power can be supplied to the low resistance ceramic member 16 from a power source (not shown).

In the heating device shown in FIG. 2, since the low resistance ceramic member 16 has conductivity, it becomes a high frequency electrode by itself and does not require the metal high frequency electrode 15 shown in FIG. Further, since the low resistance ceramic member 16 has the same diameter as the upper ceramic member 31 and the lower ceramic member 32 and is larger than the diameter of the wafer W, the plasma P generated between the counter electrode 20 From the center to the radial direction, a uniform plasma state can be obtained from the outer periphery of the wafer W to the outside. Therefore, the distribution of the plasma in the radial direction on the wafer W can be made uniform between the central portion and the peripheral portion.

The heating device shown in FIG. 2 does not require the metal high-frequency electrode 15, so that the insulating ceramic base 30 has a difference in thermal expansion coefficient between the metal high-frequency electrode and the insulating ceramic base 10. There is no risk of internal stress remaining inside. Therefore, even when the normal temperature wafer W is placed on the insulating ceramic substrate 30 that has been heated to a high temperature, almost no internal stress is generated, so that the heating device is excellent in durability.

  FIG. 3 is a cross-sectional view for explaining another embodiment of the heating device according to the present invention. In FIG. 3, the same members as those in FIGS. 1 and 2 are denoted by the same reference numerals, and redundant description is omitted below.

Heating apparatus of this embodiment shown in Figure 3, have substantially the same configuration as the pressurized heat apparatus shown in FIG. 2, and thereby connected to the low resistance ceramic member 16 is exposed to the heated surface This is an example in which pin-shaped low-resistance ceramic members 18 are disposed at the center and the peripheral edge of the heating surface, respectively. The pin-shaped low-resistance ceramic member 18 can be made of an aluminum nitride-based ceramic having a main component in common with the low-resistance ceramic member 16. The volume resistivity of the low resistance ceramic member 18 is preferably 10 Ωcm or more and less than 10000 Ωcm. As an aluminum nitride ceramic having such a volume resistivity, there is a sintered body described in Patent Document 1, which can be used.

  The heating device of the present example has not only the effect obtained by the heating device shown in FIG. 2 but also the pin-like low-resistance ceramic member 18, so that it is disposed at the center of the heating surface. The low resistance ceramic member 18 can release the plasma charge remaining on the heated surface to the outside from the low resistance ceramic member 18 via the low resistance ceramic member 16 and the electrode rod 17. Therefore, it is possible to effectively prevent the wafer W from being adsorbed by the charge remaining on the heating surface.

  Further, the low resistance ceramic member 18 disposed on the peripheral portion of the heating surface transfers the plasma charge remaining on the ring member which may be placed in this region as needed from the low resistance ceramic member 18. It can escape to the outside through the low resistance ceramic member 16 and the electrode rod 17. Therefore, arcing due to the plasma charge remaining on the ring member can be effectively prevented.

  FIG. 3 shows an example in which the pin-shaped low-resistance ceramic member 18 is disposed at the center and the peripheral edge of the heating surface, respectively. However, the heating device according to the present invention has a pin-shaped low-resistance ceramic member 18. The case where the resistance ceramic member 18 is disposed at either the central portion or the peripheral portion of the heating surface is also included.

  FIG. 4 is a cross-sectional view of an example of a conventional heating apparatus shown for comparison. In FIG. 4, the same members as those in FIGS. 1 to 3 are denoted by the same reference numerals, and redundant description is omitted below.

  In the heating apparatus shown in FIG. 4, the ceramic substrate 101 is formed with a convex portion 101a having a diameter slightly smaller than the diameter of the wafer W at the center portion on the side where the wafer W to be heated is placed. ing. The wafer W is placed on the flat upper surface of the convex portion 101a of the ceramic substrate 101 and heated.

  In addition, the high-frequency electrode 15 is embedded in the convex portion 101a of the ceramic substrate 101 and parallel to the upper surface of the convex portion 101a. The high-frequency electrode 15 is embedded in the convex portion 101a, and the diameter of the high-frequency electrode 15 is limited by the diameter of the convex portion 101a and is smaller than the diameter of the wafer W. Therefore, the plasma P generated between the high-frequency electrode 15 and the counter electrode 20 may have a difference in plasma state between the central portion and the outer peripheral portion of the wafer W, and the plasma distribution may be uneven in the radial direction. It was.

  Next, an example of the manufacturing method of the heating apparatus of this invention is demonstrated.

  First, the raw ceramic powder for the upper ceramic members 11 and 31 and the lower ceramic members 12 and 32 of the insulating ceramic bases 10 and 30 and the ceramic powder for the low resistance ceramic member 16 and the low resistance ceramic member 18 are prepared. .

  The raw ceramic powders of the upper ceramic members 11 and 31 and the lower ceramic members 12 and 32 of the insulating ceramic bases 10 and 30 are obtained by a conventionally known manufacturing method such as a reduction nitriding method, a gas phase synthesis method, or a direct nitriding method. Aluminum nitride raw material powder, and rare earth oxides such as yttrium oxide added according to the desired volume resistivity or raw material compounds of rare earth oxides, such as nitrates, sulfates, oxalates, chlorides, alkoxides, It mixes with a predetermined | prescribed compounding ratio, adds solvents, such as isopropyl alcohol, and mixes using mixing mills, such as a pot mill, a trommel, or an attrition mill. Mixing may be either wet or dry, and when wet is used, after mixing, drying is performed using a spray drying method or the like to obtain a raw material mixed powder. In addition, it is desirable to adjust the particle size of the granulated powder by sieving the dried powder after the vacuum drying method.

  The ceramic powder for the low resistance ceramic member 16 and the low resistance ceramic member 18 is prepared by mixing aluminum nitride raw material powder and carbon fiber, and more preferably rare earth oxides such as yttrium oxide in a predetermined mixing ratio, such as isopropyl alcohol. A solvent is added and mixed using a mixing and grinding machine such as a pot mill, a trommel or an attrition mill. Low resistance ceramic members can be realized by adding rare earth oxides to aluminum nitride raw material powder, but low resistance ceramic members by adding carbon fibers can easily form conductive paths in the sintered body. This is advantageous because low volume resistivity can be obtained while maintaining the characteristics of aluminum.

  As the carbon fiber, for example, a carbon fiber having a fiber diameter of 1 μm or less and an aspect ratio of 5 or more, more preferably an aspect ratio of 10 or more can be used. Carbon nanotubes can also be used.

What is necessary is just to determine the addition amount of the carbon fiber with respect to aluminum nitride raw material powder according to the electrical property and physical property required for the use of the sintered compact finally obtained. For example, when it is desired to obtain a volume resistivity of about 10 ¹² Ωcm or less while maintaining the same physical properties as those of the upper ceramic member 11 and the lower ceramic member 12 of the insulating ceramic substrate 10, the aluminum nitride raw material powder is added to 100 parts by weight. On the other hand, the amount of carbon fiber added is preferably 5 parts by weight or less, and more preferably 1 part by weight or less. In addition, when it is desired to obtain a lower volume resistivity of about 10 ⁴ Ωcm or less while having good strength, heat resistance, and corrosion resistance, the amount of carbon fiber added to 100 parts by weight of the aluminum nitride raw material powder Is preferably 20 parts by weight or less, and more preferably 10 parts by weight or less.

  Moreover, when adding rare earth oxide, Preferably the compounding ratio shall be 0.2 to 20 weight part, Preferably it is 10 weight part or less.

  Mixing these raw material powders may be either wet or dry, and when wet is used, after mixing, drying is performed using a spray drying method or the like to obtain a raw material mixed powder. Further, it is desirable to adjust the particle size by sieving the dry powder after the vacuum drying method. In addition, binder components, such as polyvinyl alcohol, can be added in raw material mixed powder. When a binder is added, it is necessary to be careful not to oxidize and lose the carbon fiber by a method in which the degreasing step is performed in an inert atmosphere such as nitrogen.

  Next, when manufacturing the insulating ceramic substrate 10, a pin-shaped low-resistance ceramic member 18 is prepared in advance as necessary. The low-resistance ceramic member 18 is produced by pressure forming raw ceramic powder into a pin shape. More preferably, the molded body obtained by this pressure molding is sintered into a pin-shaped sintered body. In short, the low-resistance ceramic member 18 may be an unsintered molded body as long as the shape of the low-resistance ceramic member 18 can be reliably maintained in the manufacturing process of the insulating ceramic substrate 10. Further, it may be a sintered body. However, since the sintered body has higher strength than the molded body and can maintain the pin shape more reliably, the sintered body is preferable.

  For pressure forming of the low resistance ceramic member 18, a mold forming method or CIP may be used, and a known method for forming ceramic powder into a pin shape may be used. In addition, the sintered compact of the low-resistance ceramic member 18 can be sintered by a known sintering method such as a hot press method, a normal pressure sintering method, or HIP. At this time, it is desirable that the atmosphere during the heating and firing of the compact is a vacuum, inert or reducing atmosphere so that the carbon fibers contained in the low-resistance ceramic member 18 are not oxidized or burned out. The firing temperature is preferably 1650 ° C. to 2200 ° C., although it varies depending on the addition amount of the sintering aid.

  In the aluminum nitride sintered body obtained after firing, carbon fibers remain in a state of being dispersed in grain boundaries and grains while maintaining the fibrous structure at the time of the raw material, and are adjacent to each other in the aluminum nitride sintered body. In contact with the carbon fiber to form a continuous three-dimensional conductive path.

  Next, the insulating ceramic substrate 10 is produced. An example of a manufacturing method in which the insulating ceramic base 10 is embedded with a resistance heating element 13 and, if necessary, a high-frequency electrode 15 is shown below. A predetermined amount of granulated powder made of the above-mentioned high-resistance ceramic powder is put into a mold and formed into a disk shape by a uniaxial press. The molded product that becomes the insulating ceramic substrate 10 can be obtained by placing the resistance heating element 13 and the raw material ceramic powder on the molded product and press-molding them.

  The granulated powder to be the low resistance ceramic described above is put on the molded body to be the insulating ceramic substrate 10 and is uniaxially pressed again. The high-frequency electrode 15 and the insulating ceramic powder are put on the granulated powder, and the layers are sequentially laminated. Press molding. The molded body or sintered body of the low-resistance ceramic member 18 described above is embedded in a predetermined position of the laminated molded body obtained as described above, if necessary. This embedding can be performed, for example, by punching a sintered body of the pin-like low-resistance ceramic member 18 in the surface of the partial molded body and pushing it in the thickness direction.

  In addition, even if it shape | molds by making the order of the above lamination | stacking reverse, it does not change at all and can obtain a lamination | stacking molded object.

  The resistance heating element 13 can be made of a refractory metal such as Mo or W made of a metal bulk body processed into a predetermined shape such as a coil shape or a spiral shape.

  The obtained molded body is heated and fired using a hot press method, an atmospheric pressure sintering method, or the like to produce a sintered body. In this firing, by using a hot press method, pressurization in the uniaxial direction is performed at the time of firing, which is advantageous because the adhesion between the electrode and the aluminum nitride sintered body can be improved.

  The firing temperature varies depending on the amount of the sintering aid added, but is preferably 1650 ° C to 2200 ° C. At this time, it is desirable that the firing atmosphere is a vacuum, an inert atmosphere, or a reducing atmosphere.

  After producing the sintered body of the ceramic body, the peripheral portion of the heating surface can be ground and processed into a shape having a convex portion at the center of the heating surface as shown in FIG. The surface roughness of the heating surface can be adjusted.

  Next, a countersink hole is provided in the lower ceramic member 12 to expose the low-resistance ceramic member 16 or the high-frequency electrode 15 and the resistance heating element 13, and a power feeding member such as a Ni bar is joined thereto by gold brazing or the like. A heating device according to the invention is obtained.

[Example 1]
An aluminum nitride powder containing 5 wt% Y ₂ O ₃ was placed in a mold having a diameter of 355 mm so that the thickness after sintering was 2 mm, and formed into a disk shape by uniaxial pressure molding. Next, a Mo mesh with a diameter of Φ290 mm to be a high frequency electrode is placed, and then the low resistance AlN raw material powder (containing 1 wt% carbon fiber and 3 wt% Y ₂ O ₃ ) has a thickness of 1 mm after sintering. And uniaxial pressure molding. Next, 5 wt% Y ₂ O ₃ -containing aluminum nitride powder was placed so that the thickness after sintering was 5 mm, and uniaxial pressure molding was performed again. Furthermore, a resistance heating element made of a Mo coil was installed, and 5 wt% Y ₂ O ₃ -containing aluminum nitride powder was placed in the mold so that the thickness after sintering would be 15 mm. Obtained.

  The compact was fired at 1900 ° C. in a nitrogen inert atmosphere in a hot press furnace. From the high-frequency electrode side of the obtained sintered body, the outer peripheral portion is cut to a depth of 2.5 mm so that the wafer mounting surface is Φ295 mm, and the low-resistance AlN surface is exposed to the outer peripheral portion. The shape of the substrate 10 was adopted. Thereafter, countersunk holes were made in the sintered body so that the two ends of the resistance heating element and the high-frequency electrode were exposed from the resistance heating element side of the obtained heater plate. Further, a conductive rod made of Ni was joined to the resistance heating element and the high-frequency electrode through Kovar and gold brazing.

[Comparative Example 1]
On the other hand, the stepped heater plate shown in FIG. 4 is made entirely of 5 wt% Y2O3-containing aluminum nitride in the same manner as in Example 1 except that the plate-like low resistance AlN member is not disposed near the heating surface. Created.

When a Si wafer is placed on these heater plates and heated to 400 ° C., a SiH ₄ / O ₂ mixed gas is allowed to flow, a high frequency voltage is applied to the high frequency electrode 15 to generate plasma, and a SiO ₂ film is formed. Generated. As a result, in the case of Example 1 using the heater plate including the low resistance AlN layer (volume resistivity 15 Ωcm), since the plasma was uniformly generated up to the outer peripheral portion of the heating surface, there was a variation in film thickness on the 300 mm Si wafer. It was less than 2%. On the other hand, in the case of Comparative Example 1 using a heater plate that does not include the low-resistance AlN layer and the high-frequency electrode made of Mo mesh has only a range of Φ290 mm, the film thickness of the outer peripheral portion of the formed SiO ₂ film is Thin film thickness variation of 5% or more.

[ Reference Example 1 ]
In Reference Example 1 , the durability of the heating device having the configuration shown in FIG. 2 was examined.

An aluminum nitride powder containing 5 wt% Y ₂ O ₃ was placed in a Φ100 mm mold so that the thickness after sintering was 2 mm, and formed into a disk shape by uniaxial pressure molding. Next, a low-resistance AlN raw material powder (containing 1 wt% carbon fiber and 3 wt% Y ₂ O ₃ ) was placed as a high-frequency electrode so that the thickness after sintering was 1 mm, and uniaxial pressing was performed. Next, aluminum nitride powder containing 5 wt% Y ₂ O ₃ was placed so that the thickness after sintering was 5 mm, and uniaxial pressure molding was performed again to obtain a molded body. This was fired at 1900 ° C. in a nitrogen inert atmosphere in a hot press furnace.

[Comparative Example 2]
Comparative Example 2 is an example having no low resistance aluminum nitride layer for comparison with Reference Example 1 .

An aluminum nitride powder containing 5 wt% Y ₂ O ₃ was placed in a Φ100 mm mold so that the thickness after sintering was 2 mm, and formed into a disk shape by uniaxial pressure molding. Next, after placing Mo mesh of Φ90mm thickness 0.2mm to be high frequency electrode, put aluminum nitride powder containing 5wt% Y ₂ O ₃ so that the thickness after sintering becomes 5.8mm and press again uniaxially Molded to obtain a molded body. This was fired at 1900 ° C. in a nitrogen inert atmosphere in a hot press furnace.

[Comparative Example 3]
Comparative Example 3 is the same as Comparative Example 2 except that no Mo mesh is disposed for reference.

An aluminum nitride powder containing 5 wt% Y ₂ O ₃ was put into a Φ100 mm mold so that the thickness after sintering was 8 mm, and formed into a disk shape by uniaxial pressure molding. This was fired at 1900 ° C. in a nitrogen inert atmosphere in a hot press furnace.

A thermal shock test was performed in which the three types of plates of Reference Example 1 , Comparative Example 2, and Comparative Example 3 were heated to a predetermined temperature in an in-air electric furnace and dropped into room temperature water, and the presence or absence of cracks was confirmed. The results are shown in Table 1.

  As can be seen from Table 1, the example using low resistance AlN for the high-frequency electrode is higher in resistance to thermal shock than the comparative example using conventional Mo, and AlN's inherent thermal shock resistance with no electrode inside It was confirmed that the residual stress during fabrication was sufficiently small.

[ Reference Example 2 ]
An aluminum nitride powder containing 5 wt% Y ₂ O ₃ was placed in a mold having a diameter of 355 mm so that the thickness after sintering was 2 mm, and formed into a disk shape by uniaxial pressure molding. Next, a low-resistance AlN raw material powder to be a high-frequency electrode was placed so that the thickness after sintering was 1 mm, and uniaxial pressure molding was performed. Next, 5 wt% Y ₂ O ₃ -containing aluminum nitride powder was placed so that the thickness after sintering was 5 mm, and uniaxial pressure molding was performed again. Furthermore, a resistance heating element made of a Mo coil was installed, and 5 wt% Y ₂ O ₃ -containing aluminum nitride powder was placed in the mold so that the thickness after sintering was 15 mm, and uniaxially molded. Obtained.

  The compact was fired at 1900 ° C. in a nitrogen inert atmosphere in a hot press furnace. The obtained sintered body was ground to a predetermined size to obtain the shape of the heating device shown in FIG. Thereafter, countersunk holes were made in the sintered body so that the two ends of the resistance heating element and the high-frequency electrode were exposed from the resistance heating element side of the obtained heater plate. Further, a conductive rod made of Ni was joined to the resistance heating element and the high-frequency electrode through Kovar and gold brazing.

  When the heating device thus obtained was used for forming the SiO2 film on the wafer in the same manner as in Example 1, the variation in the thickness of the SiO2 film was less than 2% as in the Example. Moreover, when this heating apparatus was installed in the chamber and the temperature was raised to 600 ° C., a test of placing a wafer at room temperature on the surface was repeated 10,000 times. On the other hand, when conventional Mo is used as a high-frequency electrode, a peeling crack may enter and break the heating surface above the portion where the power supply member is connected.

It is sectional drawing which shows one Example which concerns on the heating apparatus of this invention. It is sectional drawing which shows an example of a heating apparatus . It is sectional drawing which shows the other Example which concerns on the heating apparatus of this invention. It is sectional drawing of an example of the conventional heating apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Ceramic base | substrate 11a Convex part 12 Resistance heating element 14 High frequency electrode 15 Low resistance ceramic member

Claims (6)

An insulating ceramic substrate having a heating surface for heating an object to be heated;
A heating element disposed on the insulating ceramic substrate;
A high-frequency electrode made of a low-resistance ceramic member provided in the vicinity of the heating surface and in parallel with the inside of the insulating ceramic substrate;
A conductive member connected to the low-resistance ceramic member ,
The heating apparatus, wherein the low-resistance ceramic member is partially exposed on the heating surface of the insulating ceramic substrate .   The low resistance ceramic member has a pin that vertically penetrates a central portion and a peripheral portion of the insulating ceramic substrate, and a surface of the pin is exposed on a heating surface of the insulating ceramic substrate. The heating apparatus according to claim 1. The low resistance ceramic member, the width of the heating surface and parallel to the direction, heating apparatus according to claim 1 or 2, wherein greater than the diameter of the object to be heated placed on the heating surface. The heating apparatus according to any one of claims 1 to 3, wherein the low-resistance ceramic member has a main component in common with the insulating ceramic base. The heating apparatus according to claim 4 , wherein the low-resistance ceramic member and the insulating ceramic base are both aluminum nitride ceramics , and the low-resistance ceramic member is aluminum nitride containing carbon fibers. . The low resistance ceramic member and the insulating ceramic substrate, both an aluminum nitride ceramics, the low resistance ceramic member according to claim 4, characterized in that the aluminum nitride containing oxides of rare earth elements Heating device.

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