JP5202175B2 - Heater with shaft - Google Patents

Description

  The present invention relates to a heater with a shaft used for heating a wafer.

Conventionally, a heater with a shaft used for heating a wafer is known. Such a heater with a shaft is generally used by being installed in a vacuum chamber. For example, in Patent Document 1, as shown in FIG. 13, a ceramic substrate 20 that can support a wafer and has a resistance heating element embedded therein, and a metal substrate that supports the ceramic substrate 20 from the back side through an alumina ring 112 are used. The heater 110 with a shaft provided with the cylindrical shaft 30 of this is disclosed. The cylindrical shaft 30, the alumina ring 112, and the ceramic substrate 20 are fixed by bolts 114. That is, after positioning the through hole that penetrates the flange of the cylindrical shaft 30, the through hole that penetrates the alumina ring 112, and the bolt hole 116 provided on the back surface of the ceramic substrate 20 so as to be coaxial, The cylindrical shaft 30, the alumina ring 112, and the ceramic substrate 20 are integrated by inserting a bolt 114 from below the through hole of the flange of the shaft 30 and screwing it into the bolt hole 116. The material of the ceramic substrate 20 is exemplified by aluminum nitride, and the material of the cylindrical shaft 30 is exemplified by aluminum alloy. Here, the cylindrical shaft 30 and the ceramic substrate 20 are fastened by the bolts 114 because the thermal expansion coefficients are greatly different between aluminum nitride and aluminum alloy.
JP 2005-166368 A

  However, in the heater 110 with a shaft of Patent Document 1, since the cylindrical shaft 30, the alumina ring 112, and the ceramic substrate 20 are fastened by the bolts 114, a minute gap between the cylindrical shaft 30 and the alumina ring 112 or alumina. Gas leak may occur from a minute gap between the ring 112 and the ceramic substrate 20. When such a gas leak occurs, there is a possibility that the internal space of the vacuum chamber is contaminated by the air when the internal space of the cylindrical shaft 30 is made air. Further, since the above-mentioned minute gap is likely to become a thermal barrier, there is a problem that the heat of the ceramic substrate 20 is difficult to escape to the cylindrical shaft 30 and the temperature of the wafer is difficult to control. On the other hand, a heater with a shaft in which a ceramic shaft is solid-phase bonded is also conceivable, but with such a heater with a shaft there is no problem of gas leakage, but the bonding temperature is as high as the ceramic sintering temperature (approximately 2000 ° C.). There was a problem that very special equipment was required.

  The present invention has been made in view of such problems, and can be manufactured by a relatively simple manufacturing process, can prevent gas from leaking from the internal space of the cylindrical shaft, and can be heated from the cylindrical shaft. The main object is to provide a heater with a shaft that is easy to escape.

  The present invention adopts the following means in order to achieve the main object described above.

The heater with a shaft of the present invention is
A ceramic substrate made of aluminum nitride capable of supporting a wafer and having an embedded resistance heating element;
A cylindrical shaft joined to the back surface of the ceramic substrate;
With
The cylindrical shaft has at least an end portion on the ceramic substrate side made of an aluminum-silicon alloy, and the end portion is joined to the back surface of the ceramic substrate.

  In this heater with a shaft, the end on the ceramic substrate side of the cylindrical shaft is made of an aluminum-silicon alloy, and the end is joined to the back surface of the ceramic substrate. For this reason, the cylindrical shaft itself is hermetically sealed, the sealing portion of the cylindrical shaft and the ceramic substrate is hermetically sealed, or the thermal expansion coefficient of the end of the cylindrical shaft on the ceramic substrate side is determined as the thermal expansion coefficient of the ceramic substrate. It becomes possible to approach. Therefore, when the heater with a shaft is installed in the chamber, it is possible to prevent gas leakage from the internal space of the cylindrical shaft to the internal space of the chamber. Moreover, there is no thermal barrier between the cylindrical shaft and the ceramic substrate. For this reason, when plasma is generated by installing a heater with a shaft in the chamber, heat near the center of the ceramic substrate can be efficiently removed via the cylindrical shaft. Therefore, the temperature difference between the points on the ceramic substrate can be reduced, and the temperature of the wafer supported on the ceramic substrate can be easily controlled.

  In the heater with a shaft of the present invention, the cylindrical shaft can be joined by heating the end without brazing material. That is, since at least the end of the cylindrical shaft is made of an aluminum-silicon alloy, a liquid phase is generated when heated to the eutectic point (577 ° C.) of the aluminum-silicon alloy, but pressure is applied at a lower temperature. Heating while increasing the diffusion fluidity at the bonding interface of the alloy, and solid-phase bonding can be performed without causing the entire deformation. Here, the aluminum-silicon alloy preferably has a relatively large amount of silicon. In this way, high melting point silicon forms a skeleton, and an eutectic aluminum-silicon alloy serves as a binder. For this reason, deformation due to joining is less likely to occur. The cylindrical shaft may be bonded to the ceramic substrate using a brazing material made of an aluminum-silicon eutectic alloy for the purpose of lowering the bonding temperature.

  In the heater with a shaft of the present invention, the cylindrical shaft may be entirely made of an aluminum-silicon alloy, and the thermal expansion coefficient may be 0.9 to 1.1 times that of the ceramic substrate. In this case, since the difference in thermal expansion coefficient between the cylindrical shaft and the ceramic substrate is small, the bonding between the cylindrical shaft and the ceramic substrate is more easily airtight. If the thermal expansion coefficient is 0.9 to 1.1 times that of the ceramic substrate, the residual stress associated with the thermal expansion coefficient at the time of bonding generated on the ceramic substrate becomes excessive, and cracks may occur in the ceramic substrate. There is. By using an aluminum-silicon alloy for the cylindrical shaft, the cylindrical shaft can have a thermal expansion coefficient equivalent to that of the ceramic substrate. In addition, the aluminum-silicon alloy can be changed relatively easily from 23 ppm / K of aluminum to about 3 ppm / K of silicon with the composition ratio of aluminum and silicon, and is suitable for the present invention. It can be said that it is a material.

  In the heater with a shaft according to the present invention, the cylindrical shaft includes a first part made of an aluminum-silicon alloy including an end part on the ceramic substrate side, and an end part of the first part opposite to the ceramic substrate. You may have the 2nd part made from aluminum joined. In this case, since the second part is made of aluminum, the heat of the ceramic substrate can be released more efficiently, and the entire cylindrical shaft is advantageous in terms of cost compared to the case where the entire cylindrical shaft is made of aluminum-silicon alloy. . Here, “made of aluminum” is not only made of pure aluminum but also an aluminum alloy mainly composed of aluminum and having a lower silicon content than the first part aluminum-silicon alloy. Including the case where it is done.

  Thus, in the heater with a shaft of the present invention using the cylindrical shaft having the first part and the second part, the first part is entirely made of an aluminum-silicon alloy and has a thermal expansion coefficient of the ceramic substrate. It is good also as 0.9-1.1 times. In this case, since the difference in thermal expansion coefficient between the cylindrical shaft and the ceramic substrate is small, the bonding between the cylindrical shaft and the ceramic substrate is more easily airtight.

  Further, in the heater with a shaft of the present invention using a cylindrical shaft having a first part and a second part, the first part is formed by joining a plurality of aluminum-silicon alloy segments, The plurality of segments may be arranged so that a thermal expansion coefficient gradually increases from a value close to aluminum nitride to a value close to aluminum from the ceramic substrate side toward the second part. This reduces the difference in thermal expansion between the ceramic substrate and the first part of the cylindrical shaft and the difference in thermal expansion between the first part and the second part of the cylindrical shaft. Even if the cycle is repeated over a long period of time, the airtightness of the internal space of the cylindrical shaft can be maintained.

  At this time, since the first part is made of an aluminum-silicon alloy, the plurality of segments can be joined by heating without brazing. Alternatively, in the first part, the plurality of segments may be joined by heating using a brazing material made of an aluminum-silicon eutectic alloy. By doing so, it is not necessary to press the segments so that they are in close contact with each other as compared with the case where no brazing material is used, and therefore the joining operation can be performed easily. That is, the dimensional accuracy of the joint surface may be less than when no brazing material is used. Further, by using a brazing material, better sealing properties can be obtained microscopically. Moreover, you may heat using a brazing material, when joining the 1st part made from an aluminum silicon alloy, and the 2nd part made from aluminum. Although the second part made of aluminum is easily deformed when pressed when heated, there is no need to press using a brazing material, so there is no risk of deformation of the second part.

  In the heater with a shaft of the present invention, the cylindrical shaft may contain aluminum and silicon, and may not contain alkali metal or heavy metal. In this way, no contamination occurs when used in a semiconductor manufacturing apparatus.

The heater with a shaft of the present invention can be manufactured by various manufacturing methods. For example, in manufacturing the heater with a shaft of the present invention, the end of the cylindrical shaft on the ceramic substrate side is pressed against the back surface of the ceramic substrate, heated to a predetermined temperature, and then cooled to remove the end. And may be bonded to the back surface of the ceramic substrate. Here, the pressing force and temperature may be set within a numerical range in which the cylindrical shaft is liquid-phase bonded or solid-phase bonded to the ceramic substrate. For example, the pressing force is 9.8 × 10 ^{2 to} 9.8 × 10. ^The temperature may be set to ³ Pa, preferably 9.8 × 10 ^{2 to} 2.9 × 10 ³ Pa, and the temperature may be set to 500 to 580 ° C., preferably 520 to 560 ° C. Or, after heating to a predetermined temperature with a brazing material (such as a brazing material made of an aluminum-silicon eutectic alloy) interposed between the end of the cylindrical shaft on the ceramic substrate side and the ceramic substrate, cooling is performed. The end portion may be bonded to the back surface of the ceramic substrate.

  Further, as the cylindrical shaft, a first part made of an aluminum-silicon alloy including an end part on the ceramic substrate side, and a second part made of aluminum joined to the end part on the opposite side to the ceramic substrate of the first part You may employ | adopt what has. In that case, the first part and the second part may be joined to form a cylindrical shaft, and then the cylindrical shaft and the ceramic substrate may be joined. Alternatively, the first part and the ceramic substrate may be joined first. The part and the second part may be joined, or the first part, the second part, and the ceramic substrate may be joined simultaneously. At this time, as the first part, a plurality of aluminum-silicon alloy segments joined so that the coefficient of thermal expansion gradually increases from a value close to aluminum nitride to a value close to aluminum may be adopted. In that case, the plurality of segments may be joined in advance to form the first part, and then joined to the ceramic substrate or the second part, or the plurality of segments may be joined together and simultaneously the ceramic substrate and the segment that contacts the ceramic substrate. The first part and the second part may be joined after the ceramic substrate-first part assembly is joined, and the plurality of segments are joined together and at the same time the second part and the second part are in contact with the second part. May be joined to form a first part-second part assembly, and the ceramic substrate and the first part may be joined. In addition, when joining the 1st part and the 2nd part, you may join in the state which fitted the unevenness | corrugation provided in the joining surface of the 1st part, and the unevenness | corrugation provided in the joining surface of the 2nd part. At this time, in consideration of the difference in thermal expansion coefficient between the first and second parts, the unevenness of the second part is designed to be smaller than the unevenness of the first part at room temperature. The second part may expand larger than the first part immediately before reaching the temperature, and the unevenness of the first part and the unevenness of the second part may be fitted.

  Next, the best mode for carrying out the present invention will be described using examples.

  1 is a cross-sectional view of a heater 10 with a shaft of Example 1, FIG. 2 is a perspective view of a cylindrical shaft 30, FIG. 3 is a sectional view with dimensions of the cylindrical shaft 30, and FIG. 4 is a manufacturing process diagram of the heater 10 with a shaft. It is.

  The shaft-equipped heater 10 is used to heat a wafer subjected to a heat treatment such as a plasma CVD process, and is installed in a vacuum chamber (not shown). The heater 10 with a shaft includes a ceramic substrate 20 that can support a wafer and has a resistance heating element 22 embedded therein, and a cylindrical shaft 30 that is joined to the back surface of the ceramic substrate 20.

  The ceramic substrate 20 is a disk member made of aluminum nitride. In the ceramic substrate 20, a molybdenum resistance heating element is embedded as the resistance heating element 22. A first hole 24 and a second hole 26 are formed near the center of the back surface of the ceramic substrate 20. The resistance heating element 22 starts from one end 22a located substantially at the center of the ceramic substrate 20, and is wired over almost the entire surface of the ceramic substrate 20 in a so-called one-stroke manner. It reaches the end 22b. One end 22a and the other end 22b of the resistance heating element 22 are exposed to the outside from the first hole 24 and the second hole 26 of the ceramic substrate 20, respectively. In the ceramic substrate 20, a flat plate electrode 23 is also embedded as a high-frequency electrode.

  The cylindrical shaft 30 is a member made entirely of an aluminum-silicon alloy. The cylindrical shaft 30 has a step 32 in the middle, and the ceramic substrate side is a large diameter portion 34 and the opposite side of the ceramic substrate 20 is a small diameter portion 36 with the step 32 as a boundary. Flange 34a, 36a is formed in the end part of large diameter part 34, and the end part of small diameter part 36, respectively. The end of the large diameter portion 34 of the cylindrical shaft 30 is joined to the back surface of the ceramic substrate 20. Inside the cylindrical shaft 30, nickel power supply rods 38 and 38 that are brazed to one end 22 a and the other end 22 b of the resistance heating element 22 are provided along the axial direction. Electric power is supplied to the resistance heating element 22 of the ceramic substrate 20 through the power supply rods 38 and 38.

  Next, the manufacturing method of this heater 10 with a shaft is demonstrated. First, as the ceramic substrate 20, an aluminum nitride substrate having a diameter of 340 mm and a thickness of 18 mm was prepared. The thermal expansion coefficient of the ceramic substrate 20 was 5.0 ppm / K. Then, the back surface of the ceramic substrate 20, that is, the joint surface with the cylindrical shaft 30 was polished so that the surface roughness Ra was 0.5 μm. In addition, such a ceramic substrate 20 can be manufactured according to the description of the Example of Unexamined-Japanese-Patent No. 2006-232576, for example. On the other hand, an ingot made of a 20 wt% Al-80 wt% Si alloy (thermal expansion coefficient 4.9 ppm / K) is produced by a spray forming method, and the cylindrical shaft 30 having the shape and dimensions shown in FIG. 3 is cut from this ingot. Was made. The end surface of the large-diameter portion 34 of the cylindrical shaft 30, that is, the joint surface with the ceramic substrate 20, was polished so that the surface roughness Ra was 0.5 μm. Subsequently, as shown in FIG. 4, the cylindrical shaft 30 was placed on the back surface of the ceramic substrate 20 with the end of the large-diameter portion 34 of the cylindrical shaft 30 facing down. At this time, the axial center of the cylindrical shaft 30 and the center of the ceramic substrate 20 were made to coincide. And in this state, it puts in the vacuum furnace of inert gas atmosphere (here nitrogen gas atmosphere, pressure reduction 100Pa or less), and the flange 34a formed in the edge part of the large diameter part 34 is 10 kg with the cylindrical alumina jig | tool 40. FIG. It heated at 540 degreeC, pressing and applying the load of (1000 Pa), and hold | maintaining for 1 hour, Then, it cooled in the furnace. By doing so, the end of the large-diameter portion 34 of the cylindrical shaft 30 was joined to the back surface of the ceramic substrate 20. The eutectic component (88 wt% Al-12 wt% Si) in the 20 wt% Al-80 wt% Si alloy diffuses and flows by pressing at 540 ° C. and becomes a semi-liquid phase. Joined by joining (diffusion joining). Note that boron nitride powder was previously sprayed on the pressing surfaces of the alumina jig 40 and the flange 34a to prevent them from sticking to each other (the same applies to the following examples).

Next, the performance of the heater 10 with a shaft thus obtained will be described. Using a helium leak detector (model name: MSE-2000, manufacturer name: Shimadzu Corporation), the outside of the cylindrical shaft 30 is made a helium gas atmosphere by vacuuming the inside of the cylindrical shaft 30 by the hood method. Then, when the airtightness of the joint surface between the ceramic substrate 20 and the cylindrical shaft 30 was measured, the leak amount was 1 × 10 ⁻⁹ Pa · m ³ / sec or less. From this result, it was found that the joint surface between the ceramic substrate 20 and the cylindrical shaft 30 of the heater with shaft 10 has very good airtightness.

  In addition, the shaft-equipped heater 10 is installed in a vacuum chamber (not shown), and power is supplied to the resistance heating element 22 embedded in the ceramic substrate 20 in nitrogen gas 50 Pa through the power supply rods 38 and 38 and the temperature is raised to 350 ° C. Warm up. When the temperature distribution of the ceramic substrate 20 at this time was measured using an infrared temperature monitor (model name: JTG6400, manufacturer name: JEOL), it was 6 ° C. without plasma and 8 ° C. with plasma. Here, the temperature distribution means a difference between the highest temperature and the lowest temperature when an area of φ300 mm on the wafer mounting surface of the ceramic substrate 20 is measured with an infrared temperature monitor. From this result, it was found that there was almost no difference in temperature distribution depending on the presence or absence of plasma. The plasma was generated by applying high frequency power of 13.56 MHz and 1200 W between the flat plate electrode 23 embedded in the ceramic substrate 20 and the flat plate electrode (not shown) installed in the vacuum chamber. .

Furthermore, after repeating the heat cycle between room temperature and 450 ° C. 1000 times, the airtightness was measured in the same manner as before. The leak amount was still 1 × 10 ⁻⁹ Pa · m ³ / sec or less, which was good. Airtightness was maintained.

  According to the shaft-equipped heater 10 of the first embodiment described in detail above, gas leakage from the internal space of the cylindrical shaft 30 to the internal space of the vacuum chamber can be prevented when installed in the vacuum chamber. Further, since there is no thermal barrier between the cylindrical shaft 30 and the ceramic substrate 20, when the plasma is generated by installing the heater 10 with the shaft in the vacuum chamber, the heat near the center of the ceramic substrate 20 is cylindrical. It can be efficiently removed via the shaft 30 and the temperature difference between the points on the ceramic substrate 20 can be reduced. Thereby, it becomes easy to control the temperature of the wafer supported by the ceramic substrate 20.

Comparative example

  FIG. 13 is a sectional view of a heater 110 with a shaft of a comparative example. The heater 110 with a shaft is the same ceramic substrate 20 as in the first embodiment, and a cylinder similar to the first embodiment that supports the ceramic substrate 20 from the back side through an alumina ring 112 (diameter 120 mm, inner diameter 80 mm, thickness 10 mm). The shaft 30 is provided. This heater 110 with a shaft was manufactured as follows. That is, a through hole that penetrates the flange 34 a provided at the end of the large diameter portion 34 of the cylindrical shaft 30, a through hole that penetrates the alumina ring 112, and a bolt hole 116 provided on the back surface of the ceramic substrate 20. Are positioned so as to be coaxial, and then the bolt 114 is inserted from below the through hole of the flange 34a and screwed into the bolt hole 116, thereby integrating the cylindrical shaft 30, the alumina ring 112, and the ceramic substrate 20. .

Next, the performance of the heater 110 with a shaft thus obtained will be described. When the airtightness of the joint surface between the ceramic substrate 20 and the cylindrical shaft 30 was measured in the same manner as in Example 1, the leak amount was 1 × 10 ⁻³ Pa · m ³ / sec or more, and helium gas leaked. confirmed. Further, when the temperature distribution of the ceramic substrate 20 at 350 ° C. was measured in the same manner as in Example 1, it was 6 ° C. without plasma and 12 ° C. with plasma, and there was a large difference in temperature distribution depending on the presence or absence of plasma. all right.

  FIG. 5 is a sectional view of the heater 50 with a shaft according to the second embodiment, FIG. 6 is a sectional view with dimensions of the cylindrical shaft 60, and FIGS. 7 and 8 are manufacturing process diagrams of the heater 50 with a shaft.

  The heater 50 with a shaft is the same as that of the first embodiment except that the cylindrical shaft 60 is adopted instead of the cylindrical shaft 30 of the first embodiment. The description is omitted.

  The cylindrical shaft 60 has a step 62 in the middle, and the ceramic substrate side has a large-diameter portion 64 and the opposite side to the ceramic substrate 20 has a small-diameter portion 66 with the step 62 as a boundary. Flange 64 a and 66 a are formed at the end of the large diameter portion 64 and the end of the small diameter portion 66, respectively. The end of the large diameter portion 64 of the cylindrical shaft 60 is joined to the back surface of the ceramic substrate 20. Moreover, the cylindrical shaft 60 is produced by joining the 1st part P1 and the 2nd part P2. The first part P1 is a portion from the end of the large diameter portion 64 to the front of the step 62, and is made of an aluminum-silicon alloy. The end surface P1a opposite to the ceramic substrate side of the first part P1 has a concavo-convex shape in which the inner peripheral side protrudes compared to the outer peripheral side. On the other hand, the second part P2 is a part including a part of the large diameter part 64 and the entire small diameter part 66, and is made of aluminum. The end surface P2a on the side of the second part P2 facing the first part P1 has a concave-convex shape in which the inner peripheral side is immersed compared to the outer peripheral side. And the end surface P1a of the 1st part P1 and the end surface P2a of the 2nd part P2 are joined in the state by which the mutual unevenness | corrugation fits without gap. Such a joining form is called a spigot joint. The dimensions of the cylindrical shaft 60 are shown in FIG.

  Next, the manufacturing method of this heater 50 with a shaft is demonstrated based on FIG.7 and FIG.8. First, the same ceramic substrate 20 as in Example 1 was prepared. Further, an ingot made of a 20 wt% Al-80 wt% Si alloy (thermal expansion coefficient 4.9 ppm / K) was produced by a spray forming method, and a first part P1 was produced from the ingot by cutting. At this time, the end surface P1a of the first part P1 was cut so as to have an uneven shape with the inner peripheral side protruding compared to the outer peripheral side. And the joining surface with the ceramic substrate 20 of the 1st part P1 was grind | polished so that surface roughness Ra might be set to 0.5 micrometer. On the other hand, 2nd part P2 was produced using the corrosion-resistant aluminum extension material A6061. At this time, the end surface P2a of the second part P2 was cut so as to have an uneven shape in which the inner peripheral side was immersed compared to the outer peripheral side. The first part P1 and the second part P2 are dimensioned so that the second part P2 is smaller than the first part P1 in consideration of the difference in thermal expansion coefficient so that the irregularities fit each other at the bonding temperature. . Here, the clearance was set to be 0.1 mm or less in the radial direction at 540 ° C.

  Subsequently, as shown in FIG. 7, in the heating furnace, the first part P1 is placed on the back surface of the ceramic substrate 20 with the flange 64a of the first part P1 facing down, and the end surface P2a of the second part P2 is further placed. The second part P2 is placed on the end face P1a of the first part P1 so that the lower part is on the lower side. At this time, the axial centers of the first part P1 and the second part P2 were made to coincide with the center of the ceramic substrate 20. In this state, the unevenness of the second part P2 and the first part P1 is not fitted, so the outer periphery of the second part P2 is supported by the cylindrical inner alumina jig 42. In this state, the heating furnace is set to an inert gas atmosphere, and the flange 34a of the first part P1 is heated to 540 ° C. while applying a load of 10 kg (1000 Pa) by the cylindrical outer alumina jig 44. When the temperature reached 60 ° C., the inner alumina jig 42 applied the load of 4 kg (1300 Pa) to the step 62 of the second part P2, and heated it to 540 ° C. while pressing. Prior to reaching 540 ° C., the unevenness of the end face P2a of the second part P2 expanded due to thermal expansion, and as shown in FIG. 8, it was lowered by the action of gravity and fitted into the unevenness of the first part P1. Then, after hold | maintaining at 540 degreeC for 1 hour, it cooled in the furnace. By doing so, the end of the first part P1 on the flange side was joined to the back surface of the ceramic substrate 20, and the first part P1 and the second part P2 were joined.

Next, the performance of the thus obtained shaft-equipped heater 50 will be described. When the airtightness of the joint surface between the ceramic substrate 20 and the cylindrical shaft 60 was measured in the same manner as in Example 1, the leak amount was 1 × 10 ⁻⁹ Pa · m ³ / sec or less, and good airtightness was obtained. Had. Further, when the temperature distribution of the ceramic substrate 20 at 350 ° C. was measured in the same manner as in Example 1, it was 6 ° C. without plasma and 7 ° C. with plasma, and there was almost no difference in temperature distribution depending on the presence or absence of plasma. Further, when the airtightness was measured after repeating the thermal cycle between room temperature and 450 ° C. 1000 times, the leak amount was 5 × 10 ⁻⁹ Pa · m ³ / sec.

According to the heater 50 with a shaft of Example 2 explained in full detail above, in addition to the effect of Example 1, the following effects are also acquired. That is, the effect of shrink fitting can be obtained by utilizing the difference in thermal expansion coefficient between the first part P1 and the second part P2. Further, by making the pressing surface (step 62) of the second part P2 by the inner alumina jig 42 close to the end surface P2a, it becomes easy to apply a pressing force directly to the joining surface, and the portion other than the pressing surface (hollow portion or It is possible to prevent deformation due to load during high-temperature heating of the flange portion). For this reason, favorable dimensional accuracy can be obtained. Furthermore, since the ingot made of aluminum-silicon alloy can be reduced in size as compared with the first embodiment, it is extremely advantageous in terms of cost, and the second part P2 made of aluminum is the first made of aluminum-silicon alloy. Since the thermal conductivity is higher than that of the first part P1, heat near the center of the ceramic substrate 20 can be removed more efficiently through the cylindrical shaft 60. Furthermore, since the first part P1 is designed to be sufficiently long (70 mm or more in this case), the temperature of the joint part between the first part P1 and the second part P2 does not become too high, and the difference in thermal expansion coefficient between the two parts The resulting decrease in hermeticity is effectively prevented. If it is less than 70 mm, when a heater with a shaft is subjected to a thermal cycle at 450 ° C. and room temperature, a leak of 2 × 10 ⁻⁷ Pa · m ³ / sec occurs in 300 times, but it is good as described above at 70 mm or more. Results were obtained.

  The third embodiment is substantially the same as the second embodiment except that the manufacturing method of the first part P1 of the second embodiment is changed. Therefore, the same components as those of the second embodiment are denoted by the same reference numerals and the description thereof is omitted. Omitted. FIGS. 9A and 9B are explanatory views of segments used when the first part P1 of Example 3 is manufactured, in which FIG. 9A is a cross-sectional view and FIG. 9B is a plan view. FIG. 10 is a manufacturing process diagram of the first part P1 of the third embodiment. The first part P1 of Example 3 was 28 mm in height, and the second part P2 was 142 mm in height.

  In Example 3, the first part P1 was produced by joining ring-shaped first to fourth segments S1 to S4 made of an aluminum-silicon alloy. The first segment S1 is an alloy of 20 wt% Al-80 wt% Si (thermal expansion coefficient 4.9 ppm / K), the second segment S2 is an alloy of 30 wt% Al-70 wt% Si (thermal expansion coefficient 7 ppm / K), the third Segment S3 was an alloy of 55 wt% Al-45 wt% Si (thermal expansion coefficient 12 ppm / K), and the fourth segment S4 was an alloy of 75 wt% Al-25 wt% Si (thermal expansion coefficient 17 ppm / K). Each of the segments S1 to S4 is produced by grinding from an ingot produced by a spray forming method. Each joint surface is provided with a countersink hole into which a silicon pin (for positioning) can be inserted. Two locations were provided so as to be point-symmetric with respect to the center. In addition, the flange 64a was formed in 1st segment S1, and the end surface P1a which has an unevenness | corrugation was formed in 4th segment S4.

  Then, as shown in FIG. 10, the first segment S <b> 1 to the fourth segment S <b> 1 were sequentially stacked on the back surface of the ceramic substrate 20 in the heating furnace while inserting pins into the countersunk holes. At this time, the axis center of each segment S1-S4 and the center of the ceramic substrate 20 were made to correspond. In this state, the fourth segment S4 is pressed with a load of 4 kg (1300 Pa) from the inner alumina jig 46 and is pressed with a load of 10 kg (1000 Pa) by the outer alumina jig 48 on the flange 64a. The mixture was heated to 540 ° C. in an active gas atmosphere, held for 1 hour, and then cooled in the furnace. By carrying out like this, the edge part of 1st segment S1 was joined to the back surface of the ceramic substrate 20, and 1st-4th segment S1-S4 was joined, respectively. Thereafter, the second part P2 (height 142 mm) was joined to the end face P1a of the first part P1 according to the manufacturing process of Example 2, thereby obtaining the heater with a shaft of Example 3.

When the airtightness of the heater with a shaft thus obtained was measured in the same manner as in Example 1, the leak amount was 1 × 10 ⁻⁹ Pa · m ³ / sec or less, and it had good airtightness. . Further, when the temperature distribution of the ceramic substrate 20 at 350 ° C. was measured in the same manner as in Example 1, it was 6 ° C. without plasma and 6 ° C. with plasma, and there was no difference in temperature distribution depending on the presence or absence of plasma. Furthermore, when the airtightness was measured after 1000 thermal cycles between room temperature and 450 ° C., the leak rate was still 1 × 10 ⁻⁹ Pa · m ³ / sec or less, and good airtightness was maintained. It was.

  According to the heater with a shaft of the third embodiment described in detail above, the following effects can be obtained in addition to the effects of the first and second embodiments. That is, since the thermal expansion coefficient of the first part P1 gradually changes from a value close to the ceramic substrate 20 to a value close to the second part P2, the length of the first part P1 is shortened to reduce the second part P1. Even if the length of P2 is increased, there is no possibility that the airtightness between the parts is reduced due to the difference in thermal expansion. Moreover, since the length of the 2nd part P2 with high heat conductivity compared with the 1st part P1 can be lengthened, generation | occurrence | production of the temperature distribution by the presence or absence of a plasma can be suppressed more effectively. Furthermore, since the joining surfaces of the segments S1 to S4 and the joining surfaces of the first part P1 and the second part P2 become a strong and airtight interface and the generated thermal stress is reduced, even after a long repeated thermal cycle. High airtightness is maintained. Further, since most of the shaft portion is made of aluminum having a good thermal conductivity, the heat escape from the shaft portion is good, and the temperature change of the plate due to the presence or absence of plasma can be better controlled.

  The fourth embodiment is substantially the same as the second embodiment except that the manufacturing method of the first part P1 of the second embodiment is changed. Therefore, the same components as those of the second embodiment are denoted by the same reference numerals and the description thereof is omitted. Omitted. FIG. 11 is a cross-sectional view of a segment used when manufacturing the first part P1 of Example 4, and FIG. 12 is a manufacturing process diagram of the heater with a shaft of Example 4. The first part P1 of Example 4 was 28 mm in height, and the second part P2 was 142 mm in height.

  In Example 4, the first part P1 was produced by joining the ring-shaped first to fourth segments S11 to S14 shown in FIG. The material of each segment S11-S14 is the same as each segment S1-S4 of Example 3. In addition, each of the segments S11 to S14 was prepared by grinding from an ingot produced by a spray forming method, and each joint surface was provided with concavities and convexities that fit each other so that the spigot joint was possible. .

  Then, as shown in FIG. 12, a doughnut-shaped foil (outer diameter 100 mm, inner diameter 91 mm, thickness 0.05 mm) made of an alloy of 88 wt% Al-12 wt% Si is placed on the back surface of the ceramic substrate 20 in the heating furnace. Then, the first segment S1 to the fourth segment S1 were laminated in that order while sandwiching the same foil as before, and the second part P2 was further placed thereon via the foil. At this time, the axial centers of the segments S1 to S4, the center of the ceramic substrate 20, and the axial center of the second part P2 were made to coincide. Such positioning was performed by using the inner alumina jig 42 and the outer alumina jig 44 used in Example 2. At this time, the outer alumina jig 44 also served as a guide for the inner alumina jig 42. In this state, the alumina jigs 42 and 44 were heated to 540 ° C. in an inert gas atmosphere without applying a load, held for 1 hour, and then cooled in the furnace. In this way, a heater with a shaft was obtained.

When the airtightness of the heater with a shaft thus obtained was measured in the same manner as in Example 1, the leak amount was 1 × 10 ⁻⁹ Pa · m ³ / sec or less, and the airtightness was good. . Further, when the temperature distribution of the ceramic substrate 20 at 350 ° C. was measured in the same manner as in Example 1, it was 6 ° C. without plasma and 6 ° C. with plasma, and there was no difference in temperature distribution depending on the presence or absence of plasma. Furthermore, when the airtightness was measured after 1000 thermal cycles between room temperature and 450 ° C., the leak rate was still 1 × 10 ⁻⁹ Pa · m ³ / sec or less, and good airtightness was maintained. It was.

  According to the heater with a shaft of the fourth embodiment described in detail above, the following effects can be obtained in addition to the effects of the third embodiment. That is, since it can join only with the weight of each component and a jig | tool, a manufacturing process is simplified compared with Example 3. FIG.

  In addition, this invention is not limited to the Example mentioned above at all, and as long as it belongs to the technical scope of this invention, it cannot be overemphasized that it can implement with a various aspect.

  For example, in each of the above-described embodiments, the cylindrical shafts 30 and 60 are provided with the steps 32 and 62. However, the steps 32 and 62 may be eliminated to form a straight shaft.

  In Examples 1 to 3 described above, solid phase bonding or liquid phase bonding is performed between the ceramic substrate 20 and the cylindrical shafts 30 and 60 without using a brazing material, but the brazing material (for example, 88 wt% of Example 4). Bonding may be performed using a foil made of an alloy of Al-12 wt% Si.

  In Example 3 mentioned above, the 1st-4th segment S1-S4 is laminated | stacked on the ceramic substrate 20, and the assembly of the ceramic substrate 20 and 1st-4th segment S1-S4 is heated and joined in the state. However, only the first to fourth segments S1 to S4 may be laminated to produce the first part P1, and then the heater with a shaft may be produced in the same manner as in Example 2. Or the 2nd part P2 is laminated | stacked on the 1st-4th segments S1-S4, the cylindrical shaft 60 is produced by heating and joining in that state, and it is the heater with a shaft similarly to Example 1 after that. May be produced.

Sectional drawing of the heater 10 with a shaft of Example 1. FIG. The perspective view of the cylindrical shaft 30. FIG. 3 is a cross-sectional view with dimensions of a cylindrical shaft 30. The manufacturing process figure of the heater 10 with a shaft. Sectional drawing of the heater 50 with a shaft of Example 2. FIG. A sectional view with dimensions of a cylindrical shaft 60. FIG. The manufacturing process figure of the heater 50 with a shaft. The manufacturing process figure of the heater 50 with a shaft. It is explanatory drawing of 1st-4th segment S1-S4 used in Example 3, (a) is sectional drawing, (b) is a top view. FIG. 6 is a manufacturing process diagram of a cylindrical shaft used in Example 3. Sectional drawing of 1st-4th segment S11-S14 used in Example 4. FIG. FIG. 6 is a manufacturing process diagram of a heater with a shaft according to a fourth embodiment. Sectional drawing of the heater 110 with a shaft of a comparative example.

Explanation of symbols

  10, 50, 110 Heater with shaft, 20 ceramic substrate, 22 resistance heating element, 22a one end, 22b other end, 23 flat plate electrode, 24 first hole, 26 second hole, 30, 60 cylindrical shaft, 32, 62 steps 34, 64 Large diameter part, 34a, 36a, 64a, 66a Flange, 36, 66 Small diameter part, 38 Feed rod, 40 Alumina jig, 42, 46 Inner alumina jig, 44, 48 Outer alumina jig, 112 Alumina Ring, 114 bolt, 116 bolt hole, P1 first part, P1a, P2a end face, P2 second part, S1 to S4, S11 to S14 First to fourth segments.

Claims (6)

A ceramic substrate made of aluminum nitride capable of supporting a wafer and having an embedded resistance heating element;
A cylindrical shaft joined to the back surface of the ceramic substrate;
With
The cylindrical shaft is joined to a first part made of an aluminum-silicon alloy including an end part joined to a back surface of the ceramic substrate, and an end part of the first part opposite to the ceramic substrate. A second part made of aluminum,
Heater with shaft. The cylindrical shaft is joined by heating the end without brazing material,
The heater with a shaft according to claim 1. The first part is entirely made of an aluminum-silicon alloy and has a thermal expansion coefficient of 0.9 to 1.1 times that of the ceramic substrate.
The heater with a shaft according to claim 1 or 2 . The first part is formed by joining a plurality of aluminum-silicon alloy segments, and the plurality of segments has a coefficient of thermal expansion close to that of aluminum nitride from the ceramic substrate side toward the second part. It is arranged to gradually increase to a value close to aluminum,
The heater with a shaft according to claim 1 or 2 . The first part is joined by heating the plurality of segments without brazing material,
The heater with a shaft according to claim 4 . In the first part, the plurality of segments are joined by heating using a brazing material made of an aluminum-silicon alloy,
The heater with a shaft according to claim 4 .

Images