JP5942380B2 - Wafer holder for semiconductor manufacturing equipment - Google Patents

Description

  The present invention relates to a wafer holder for a semiconductor manufacturing apparatus on which a semiconductor wafer is placed and a film forming process such as CVD or a process such as etching is performed.

  2. Description of the Related Art In a semiconductor manufacturing apparatus that performs processing such as CVD and etching on a semiconductor wafer, a wafer holder that mounts and heats the semiconductor wafer is used. Various materials mainly composed of aluminum nitride have been proposed for wafer holders as shown in Patent Document 1, and some of them have already been put into practical use. Since aluminum nitride has high corrosion resistance, the use of aluminum nitride for the wafer holder can improve the corrosion resistance against halogen-based corrosive gas used in the process such as CVD.

Japanese Patent Publication No. 6-28258

  Although the corrosion resistance can be improved by configuring the wafer holder with a material mainly composed of aluminum nitride as described above, since aluminum nitride is a kind of ceramics, the problem of being weak against tensile stress is unavoidable. This sometimes becomes a problem in terms of reliability.

  For example, in the case of a wafer holder comprising a ceramic substrate having a wafer placement surface and a cylindrical support for supporting the ceramic substrate, the ceramic substrate generally has a disk shape for placing the wafer. In such a disk-shaped ceramic substrate, when the temperature of the outer peripheral portion becomes higher than the temperature of the central portion or the inner peripheral portion, the thermal expansion amount of the outer peripheral portion becomes relatively larger than that of the central portion or the inner peripheral portion. As a result, a tensile stress acts from the central portion toward the outer peripheral portion, which may cause a problem that the ceramic substrate is damaged.

  In addition, with the recent miniaturization of wiring, the demand for uniform temperature of the wafer (that is, uniform temperature of the wafer surface) when processing a semiconductor wafer has become increasingly severe. In order to make the temperature of the wafer surface uniform, it is a matter of course that the thermal uniformity of the ceramic substrate is also required. Further, in the ceramic substrate, since the heat radiation amount from the outer peripheral portion is relatively larger than the heat radiation amount in the central portion, it is necessary to make the temperature of the outer peripheral portion higher than that in the central portion. However, when the temperature of the outer peripheral portion is increased in this way, there is a possibility that the ceramic substrate may be damaged due to tensile stress as described above.

  By the way, generally, the cylindrical support for supporting the ceramic substrate is made of a ceramic sintered body made of the same material as the ceramic substrate, and one end thereof is airtightly bonded to the surface of the ceramic substrate opposite to the wafer mounting surface. The other end is installed at the bottom of the chamber. Inside the cylindrical support, a heating element embedded in the ceramic substrate, a high-frequency electrode circuit, an electrode terminal for supplying power to the electrode circuit for the electrostatic chuck, and a thermoelectric for measuring the temperature of the wafer holder. A pair, a resistance temperature detector, and lead wires connected to them are housed. Thereby, the above-described electrode terminal, thermocouple, and the like are protected from the atmosphere in the chamber.

  However, the bottom of the chamber in which the cylindrical support is installed is generally at a lower temperature than the heating temperature when the wafer holder is heated, and in some cases, the low temperature is maintained by water cooling. Therefore, when one end of the cylindrical support is bonded to, for example, the center of the ceramic substrate, the heat at the center of the ceramic substrate is taken away by the chamber through the cylindrical support, and the center of the ceramic substrate is The temperature sometimes dropped locally.

  Further, the joining of the cylindrical support has a function of preventing the ceramic substrate from being deformed. That is, by bonding the cylindrical support to the surface of the ceramic substrate opposite to the wafer mounting surface, the temperature of the opposite surface relative to the wafer mounting surface is relatively lowered, and the wafer mounting is reduced. The stress which warps so as to be convex on the surface side acts on the ceramic substrate. However, since the cylindrical support is bonded to the ceramic substrate, the warpage is hindered, and there arises a problem that a large tensile stress is applied to the bonded portion of the cylindrical support or its vicinity in the ceramic substrate. was there.

  In order to solve the above-described problems, a wafer holder for a semiconductor manufacturing apparatus provided by the present invention includes a substrate having a heat generating element embedded therein and made of a material mainly composed of aluminum nitride, and mechanically attached to the substrate. A cylindrical support body that is coupled to and supports the cylindrical body, and a cylindrical body that houses a temperature measuring element for measuring the temperature of the substrate is provided inside the support body. The inside is an air atmosphere and is isolated from the atmosphere inside the support.

  Another wafer holder for a semiconductor manufacturing apparatus provided by the present invention has a plurality of embedded heating elements, a substrate made of a material mainly composed of aluminum nitride, and mechanically coupled to the substrate. And at least one of the plurality of heating elements mainly heats the inner peripheral portion of the substrate, and at least one other one of the outer peripheral portions of the substrate. A plurality of temperature measuring elements are respectively installed on the substrate corresponding to the heating elements for heating the inner peripheral portion and the outer peripheral portion, respectively, and at least of the plurality of temperature measuring elements. One is housed in a cylindrical body provided inside the support, and the inside of the cylindrical body is an air atmosphere and is isolated from the atmosphere inside the support. .

  According to the present invention, it is possible to provide a wafer holder that is less likely to break the wafer holder due to thermal stress and is excellent in heat uniformity.

It is a longitudinal cross-sectional view which shows typically a specific example of the wafer holder for semiconductor manufacturing apparatuses of this invention. It is a longitudinal cross-sectional view which shows typically the modification of the wafer holder shown in FIG. It is a longitudinal cross-sectional view which shows typically the other specific example of the wafer holder for semiconductor manufacturing apparatuses of this invention. It is a longitudinal cross-sectional view which shows typically the modification of the wafer holder shown in FIG. 6 is a longitudinal sectional view schematically showing a wafer holder produced in Comparative Example 1. FIG. 10 is a longitudinal sectional view schematically showing a wafer holder produced in Comparative Example 2. FIG. 10 is a longitudinal sectional view schematically showing a wafer holder produced in Comparative Example 3. FIG. 6 is a longitudinal sectional view schematically showing a wafer holder produced in Comparative Example 4. FIG.

  A specific example of the wafer holder for a semiconductor manufacturing apparatus according to the present invention will be described with reference to FIG. The wafer holder shown in FIG. 1 has a substantially disk-shaped ceramic substrate 1 having a wafer mounting surface 1a. The ceramic substrate 1 is made of a material mainly composed of aluminum nitride. The reason for this is that halogen-based corrosive gas typified by fluoride-based corrosive gas is used in semiconductor manufacturing equipment such as CVD equipment and etching equipment when processing such as etching and cleaning. This is because aluminum nitride is excellent in corrosion resistance against such corrosive gas.

  Moreover, since aluminum nitride is a ceramic having a relatively high thermal conductivity, it is possible to ensure high thermal uniformity when a wafer is placed and film formation is performed. Thereby, a uniform film thickness can be formed. In addition, as a material mainly composed of aluminum nitride, in addition to an AlN sintered body made of only aluminum nitride excluding inevitable impurities, a sintering aid such as a rare earth element containing yttrium or an alkaline earth metal was contained. An AlN sintered body can be used.

  A heating element 2 is embedded in the ceramic substrate 1, whereby the wafer placed on the wafer placement surface 1 a can be heated during a predetermined process such as film formation. The material of the heating element 2 is not particularly limited, but tungsten, molybdenum, alloys thereof, and the like are preferable in consideration of a difference in thermal expansion coefficient from aluminum nitride which is a main component of the ceramic substrate 1. . The heating element 2 can be formed, for example, by applying a paste containing the above metal by a method such as screen printing and then sintering.

  A high-frequency electrode circuit 3 is further embedded in the ceramic substrate 1, whereby plasma can be generated in a chamber in which the wafer holder is installed. The ceramic substrate 1 may be embedded with an electrostatic chuck electrode circuit that chucks the wafer on the wafer mounting surface by electrostatic force. Similarly to the heating element 2, the high-frequency electrode circuit 3 and the electrode circuit for the electrostatic chuck are also suitable materials such as tungsten, molybdenum, and alloys thereof, and after applying the paste containing the metal by screen printing. It can be formed by sintering.

  The wafer holder of this specific example has a cylindrical support 4 that supports the ceramic substrate 1 in which the heating element 2 and the high-frequency electrode circuit 3 are embedded from the surface opposite to the wafer mounting surface 1a. Yes. The cylindrical support 4 is mechanically coupled to the ceramic substrate 1. Thus, unlike the case where the cylindrical support 4 and the ceramic substrate 1 are chemically bonded using a bonding agent such as brazing material, glass, or an inorganic adhesive, a highly reliable bond is realized. Can do.

  That is, in the conventional chemical bonding, as described above, if the temperature distribution on the surface of the wafer mounted on the wafer mounting surface of the ceramic substrate is made uniform, the bonding between the cylindrical support and the ceramic substrate is performed. A large stress was applied to the part, and in some cases, the ceramic substrate itself could be damaged. On the other hand, since the ceramic substrate and the cylindrical support are mechanically coupled to each other in this specific example, the stress can be relieved.

  As a specific structure of the mechanical coupling, for example, as shown in FIG. 1, a flange portion 4a is formed at a coupling side end portion of the cylindrical support body 4 with the ceramic substrate 1, and the flange portion 4a is circumferentially provided. A plurality of bolt holes are provided at equal intervals, and bolts 6 such as tungsten and molybdenum are implanted at positions corresponding to the bolt holes in the ceramic substrate 1.

  The cylindrical support 4 can be mechanically coupled to the ceramic substrate 1 by inserting the bolt 6 through the bolt hole of the flange portion 4 a and then tightening the bolt 6 with the nut 7. In addition, it is preferable to seal between the cylindrical support body 4 and the chamber bottom part 50 with sealing members, such as an O-ring.

  As another specific structure of the mechanical coupling, a metal bulk such as tungsten or molybdenum having a relatively small difference in thermal expansion coefficient with respect to aluminum nitride which is a main component of the material of the ceramic substrate 1 is provided in the ceramic substrate 1. A material is embedded, and a female screw is formed at a position corresponding to the bolt hole of the flange portion 4a in the metal bulk material. Then, the cylindrical support 4 is coupled to the ceramic substrate 1 by inserting a male screw into the bolt hole of the flange portion 4a of the cylindrical support 4 and screwing it into the female screw of the metal bulk material. Also good.

  In this way, the ceramic substrate 1 and the cylindrical support 4 are mechanically joined instead of chemically joined, for example, between the bolt hole and the bolt described above, between the male screw and the female screw, or the like. It is possible to generate a slight gap (play), thereby relieving the stress generated due to the difference in thermal expansion coefficient between the two.

  There is no restriction | limiting in particular in the material of the cylindrical support body 4, For example, metals, such as stainless steel, aluminum, nickel, or these alloys, and ceramics, such as aluminum nitride, an alumina, and a mullite, can be used. Of these materials, aluminum nitride is preferable, and naturally, the same material as that of the ceramic substrate 1 is most preferable.

  This is because aluminum nitride is excellent in corrosion resistance and has a thermal expansion coefficient equivalent to that of the ceramic substrate 1, so that the stress applied to the ceramic substrate 1 and the cylindrical support body 4 can be suppressed most at or near the joint. . Other than aluminum nitride, mullite having a coefficient of thermal expansion relatively close to that of aluminum nitride and composites containing mullite as a main component can also be suitably used.

  Inside the cylindrical support 4, a conductor 8 such as a lead wire for feeding or grounding the heating element 2 and the high-frequency electrode circuit 3 embedded in the ceramic substrate 1 is housed. Thus, by storing the conductor (also referred to as an electrode terminal or simply an electrode) 8 inside the cylindrical support 4, the conductor 8 can be protected from the corrosive atmosphere in the chamber. The conductor 8 is further covered with an insulating pipe 9 whose both ends are hermetically sealed. Thereby, the conductor 8 can be more reliably protected from the corrosive atmosphere in the chamber. Instead of the insulating pipe 9 or in addition to the insulating pipe 9, the surface of the conductor 8 may be subjected to nickel plating having corrosion resistance.

  The structure of the conductor 8 and its insulating pipe 9 will be described in detail. As shown in FIG. 1, one end of the conductor 8 is electrically connected to the heating element 2 and the high-frequency electrode circuit 3, The end passes through the bottom 50 of the chamber and reaches the outside of the chamber. Further, one end of the insulating pipe 9 surrounding the conductor 8 is in close contact with the lower surface of the ceramic substrate 1 by a brazing material or the like, and the other end penetrates the through hole of the conductor 8 in the bottom 50 of the chamber. To the outside of the chamber.

  The space between the inner wall of the through hole provided in the bottom 50 and the outer peripheral surface of the insulating pipe 9 is hermetically sealed by a sealing member 10 such as an O-ring. With this structure, the inside of the insulating pipe 9 can be isolated from the space outside the insulating pipe 9. When the terminal of the high-frequency electrode circuit 3 is grounded, it can be grounded without taking the terminal out of the chamber. Also, a conductor electrically connected to the electrostatic chuck electrode circuit can be protected from a corrosive atmosphere using an insulating pipe and nickel plating similar to those described above.

  In this specific example, the wafer holder is further provided with a temperature measuring element 11 such as a thermocouple or a resistance temperature detector for measuring the temperature of the ceramic substrate 1 inside the cylindrical support 4. The temperature measuring element 11 is housed in a cylindrical body 12 whose both ends are hermetically sealed in the same manner as the insulating pipe 9 described above, so that the temperature measuring element 11 can be removed from the corrosive atmosphere in the chamber. It is possible to protect and perform accurate temperature measurement.

  More specifically, a bottomed hole is provided on the surface of the ceramic substrate 1 opposite to the wafer mounting surface 1a, and a temperature measuring element 11 is attached thereto. The temperature measuring element 11 or a lead wire electrically connected thereto extends inside the cylindrical support 4 and further reaches the outside of the chamber through a through hole provided in the bottom 50 of the chamber.

  On the other hand, the cylindrical body 12 surrounding the temperature measuring element 11 or the lead wire is hermetically joined to the ceramic substrate 1 using a brazing material or the like, and the other end is the above-mentioned of the chamber bottom 50. It penetrates the through hole, reaches the outside of the chamber, and is open to the atmosphere. The space between the inner wall of the through hole and the outer peripheral surface of the cylindrical body 12 is hermetically sealed by a sealing member 10 such as an O-ring. Thereby, while making the inner side of the cylindrical body 12 into air atmosphere, it becomes possible to isolate the inner side of the cylindrical body 12 from the atmosphere of the outer side, ie, the atmosphere inside the cylindrical support body 4. FIG.

  Thus, by isolating the inside of the cylindrical body 12 from the outside and making the inside an air atmosphere, temperature measurement by the temperature measuring element 11 such as a thermocouple or a resistance temperature detector housed inside the cylinder 12 is extremely accurate. become. The reason is that the temperature measuring element 11 such as a thermocouple is in contact with the object to be measured and measures its temperature, so that there is inevitably a minute gap between the object to be measured and the temperature measuring element 11. ing. Therefore, if the atmosphere around the temperature measuring element 11 fluctuates, the type and number of gas molecules existing between the temperature measuring element 11 and the object to be measured even when the temperature of the object to be measured does not substantially change. Changes and the heat transfer coefficient changes, which makes temperature measurement unstable.

  That is, the temperature monitored by the temperature measuring element 11 is influenced by gas molecules existing around the temperature measuring element 11, but as described above, the inside of the cylindrical body 12 is isolated from the outside. At the same time, since the inside of the cylindrical body 12 is in an air atmosphere, the atmosphere around the temperature measuring element 11 such as a thermocouple or a resistance temperature detector housed inside the cylindrical body 12 is stabilized and extremely accurate. Temperature measurement is possible.

  As described above, in the wafer holder for a semiconductor manufacturing apparatus according to an embodiment of the present invention, the cylindrical support is mechanically coupled to the ceramic substrate, thereby acting between the cylindrical support and the ceramic substrate. Stress can be relaxed. Furthermore, by providing a cylindrical body hermetically sealed inside the cylindrical support and storing a temperature measuring element for measuring the temperature of the ceramic substrate inside thereof, the temperature of the ceramic substrate can be accurately measured. Can do. Thereby, even if the temperature distribution of the ceramic substrate becomes a so-called center cool, the wafer holder is not easily damaged, and a wafer holder excellent in heat uniformity can be provided.

  In the above description, the heating element and the high-frequency electrode circuit embedded in the ceramic substrate were formed by sintering a paste containing metal, but the present invention is not limited to this. A metal foil or coil may be used, and a metal foil or mesh may be used for the high-frequency electrode circuit.

  For example, FIG. 2 shows a wafer holder having a ceramic substrate 21 in which a heating element 22 made of a metal coil and a high-frequency electrode circuit 23 made of a metal mesh are embedded. Molybdenum terminals 24 and 25 are attached to the heating element 22 and the high-frequency electrode circuit 23, respectively, and the conductor 8 is electrically connected through the terminals 24 and 25. 2 and the subsequent drawings, the same members as those shown in FIG. 1 are denoted by the same reference numerals.

  Next, another specific example of the wafer holder for a semiconductor manufacturing apparatus according to the present invention will be described with reference to FIG. The wafer holder shown in FIG. 3 includes a ceramic substrate 101 made of a material mainly composed of aluminum nitride, and a cylindrical support 4 that is mechanically coupled to and supports the ceramic substrate 101. ing. A plurality of heating elements 102 are embedded in the ceramic substrate 101, at least one of which mainly heats the inner peripheral portion of the ceramic substrate 101, and at least one other is the outer periphery of the ceramic substrate 101. The main part is heated.

  As described above, in the wafer holder shown in FIG. 3, in addition to the cylindrical support 4 being mechanically coupled to the ceramic substrate 101, the heating of the ceramic substrate 101 is performed at the inner peripheral portion and the outer peripheral portion. Done separately. As a result, in addition to being less likely to break at the joint between the ceramic substrate 101 and the cylindrical support 4, excellent temperature controllability and thermal uniformity are obtained, and an extremely reliable wafer holder is provided. can do.

  More specifically, the plurality of heating elements 102 embedded in the ceramic substrate 101 include those that mainly control the temperature of the inner peripheral portion and those that mainly control the temperature of the outer peripheral portion. Thus, by embedding a plurality of heating elements 102 in separate regions (zones) of the ceramic substrate 101, the temperature of the ceramic substrate 101 can be controlled separately for each region, and the heat uniformity is more excellent. A wafer holder can be realized.

  Thus, even when film formation is performed under a plurality of temperature conditions or when the wafer diameter is increased to 12 inches or 18 inches, the heat uniformity can be improved relatively easily. Note that the plurality of heating elements 102 may be embedded so as to be separated from each other or partially overlap when the ceramic substrate 101 is viewed in plan.

  By the way, when the ceramic substrate is enlarged for a 12-inch wafer or an 18-inch wafer, if the cylindrical support is chemically bonded to the ceramic substrate, the stress applied to the bonded portion is processed on the 8-inch wafer. This is significantly larger than a wafer holder of a size to be used. Therefore, if the temperature of the vicinity of the center of the ceramic substrate is relatively low compared to the outer periphery in order to heat the wafer mounted on the wafer mounting surface of the ceramic substrate to a uniform temperature, the wafer is relatively easy. The holder will be damaged.

  In order to avoid this problem, also in the wafer holder shown in FIG. 3, the cylindrical support 4 that supports the ceramic substrate 101 is mechanically coupled to the ceramic substrate 101. Thereby, similarly to the wafer holder shown in FIG. 1 described above, it is possible to significantly reduce the stress acting on the coupling portion or the vicinity thereof.

  The wafer holder shown in FIG. 3 has a temperature measuring element 113 for measuring the temperature of the outer peripheral portion in addition to the temperature measuring element 111 for measuring the temperature of the inner peripheral portion of the ceramic substrate 101. These temperature measuring elements 111 and 113 enable temperature control with higher accuracy and facilitate the temperature balance between the inner and outer peripheral portions of the ceramic substrate 101. As a result, it is possible to provide a wafer holder that is more excellent in heat uniformity. In this case, the temperature measuring elements 111 and 113 installed in the inner peripheral portion and the outer peripheral portion naturally heat the region where the heating element for heating the inner peripheral portion of the ceramic substrate 101 is embedded and the outer peripheral portion, respectively. It is installed in the area where the heating element is buried.

  The temperature measuring element 111 installed in the inner peripheral portion is protected by a cylindrical body 112 provided inside the cylindrical support body 4 in the same manner as the wafer holder shown in FIG. On the other hand, in order to accurately measure the temperature of the temperature measuring element 113 installed on the outer peripheral portion, the temperature measuring element 113 is protected by a cylindrical body as in the temperature measuring element 111 installed on the inner peripheral portion. It is preferable to measure the temperature with.

  However, in order to protect the temperature measuring element 113 installed on the outer peripheral part in the same manner as the temperature measuring element 111 installed on the inner peripheral part, outside the region where the cylindrical support 4 is bonded on the ceramic substrate 101. Therefore, it is necessary to attach a cylindrical body for protecting the temperature measuring element 113 in an airtight manner. Further, in the chamber in which the wafer holder is installed, it is necessary to make another through hole in a region other than the bottom of the chamber in which the cylindrical support 4 is installed, and to hermetically seal between the through hole and the cylindrical body. There is. Thus, the structure of the apparatus becomes complicated, and the maintenance work becomes complicated when the wafer holder itself is replaced, and the risk of accidentally damaging the ceramic substrate 101 and the cylindrical body increases.

  In order to avoid the above problem, in the wafer holder shown in FIG. 3, the temperature measuring element 111 installed inside the cylindrical support 4 is protected by a cylindrical body sealed at both ends. No cylindrical body is provided in the temperature measuring element 113 for measuring the outer peripheral portion installed outside the 4. As a result, handling of the wafer holder is facilitated, and a predetermined counterbore hole is formed in the ceramic substrate, and the temperature measurement of the outer peripheral portion of the ceramic substrate 101 is very simply performed by pressing a temperature measuring element such as a thermocouple there. Can be performed.

  By not storing the temperature measuring element 113 provided in the outer peripheral part in the cylindrical body, the temperature measurement by the temperature measuring element 113 may vary to some extent, but the temperature of the inner peripheral part and the temperature of the outer peripheral part may be controlled separately. Therefore, the temperature balance between the inner peripheral portion and the outer peripheral portion of the ceramic substrate 101 can be favorably achieved. Therefore, it is possible to avoid the problem that the ceramic substrate 101 becomes a significant center cool and is damaged. It is also possible to achieve extremely high heat uniformity.

  In the so-called one-zone heater that heats the entire ceramic substrate using one heating element such as the wafer holder shown in FIG. 1 described above, a temperature measuring element such as a thermocouple is provided outside the cylindrical support. You may install without protecting with a shape. Thereby, the temperature of the outer peripheral part of a ceramic substrate can be measured. When installing, similarly to the temperature measuring element 113 described above, a counterbored hole is formed outside the cylindrical support on the surface of the ceramic substrate opposite to the wafer mounting surface, and the temperature measuring element is formed in the counterbored hole. Can be inserted.

  By the way, the temperature distribution of the ceramic substrate in a steady state is usually determined by the environment around the wafer holder, the material of the wafer holder itself, and the like. It is determined almost uniquely by the circuit pattern of the body. For this reason, it seems that there is almost no merit which installs temperature measuring elements, such as a thermocouple, in the outer peripheral part of a ceramic substrate.

  However, in the temperature rising process, a temperature difference is generated between the central portion and the outer edge portion of the ceramic substrate due to the temperature rising rate or the like. Therefore, when the temperature is increased while keeping the in-plane temperature difference of the ceramic substrate constant, or when the wafer holder is prevented from being damaged due to an extreme temperature difference between the inner and outer peripheral parts, the outer peripheral part is measured. There is merit in installing temperature element and monitoring temperature.

  In another specific example of the wafer holder for a semiconductor manufacturing apparatus of the present invention described above, the heating element 102 and the high-frequency electrode circuit 103 embedded in the ceramic substrate 101 are formed by sintering a paste containing metal. However, the present invention is not limited to this, and a metal foil or coil may be used for the heating element, or a metal foil or mesh may be used for the high-frequency electrode circuit.

  For example, FIG. 4 shows a wafer holder having a ceramic substrate 121 in which a heating element 122 made of a metal coil and a high-frequency electrode circuit 123 made of a metal mesh are embedded. Molybdenum terminals 124 and 125 are attached to the heating element 122 and the high-frequency electrode circuit 123, respectively, and the conductor 108 is electrically connected through the terminals 124 and 125. 4 and subsequent drawings, the same members as those shown in FIG. 3 are denoted by the same reference numerals.

  As described above, various specific examples of the wafer holder for a semiconductor manufacturing apparatus according to the present invention have been described. However, the present invention is not limited to these specific examples, and various modifications can be made without departing from the gist of the present invention. Alternatives and variations can be considered. That is, the technical scope of the present invention covers the claims and their equivalents.

Example 1
A substrate made of aluminum nitride (AlN) having a diameter of 320 mm and a thickness of 8 mm was prepared, and a tungsten paste was applied to one surface thereof by screen printing to form a heating element pattern consisting of one zone. A circular pattern as a high-frequency electrode circuit was formed on the other surface by the screen printing method in the same manner as described above. Next, this was degreased in a nitrogen atmosphere at 700 ° C. and then fired in a nitrogen atmosphere at 1800 ° C.

A paste mainly composed of AlN—Al ₂ O ₃ —Y ₂ O ₃ is applied to both sides of the AlN substrate on which the heating element and the high-frequency electrode circuit formed of the tungsten layer are formed in this manner, and a nitrogen atmosphere at 700 ° C. Degreased in. After degreasing, a separately prepared AlN substrate having a diameter of 320 mm and a thickness of 8 mm is superimposed on the surface on which the heating element is formed, and a separately prepared AlN substrate having a diameter of 320 mm and a thickness of 3 mm is further formed on the surface on which the high-frequency electrode circuit is formed. Superimposed. This was joined in a hot press furnace at 1750 ° C. and a pressure of 50 t.

  Next, in the joined body obtained above, countersink processing was performed in the vicinity of the electrode lead-out portion of the heating element and the external electrode placement of the high-frequency electrode circuit to expose the buried tungsten layer. A tungsten paste was applied to these exposed portions and baked in a nitrogen atmosphere at 1700 ° C. to form a metallized layer. Next, a nickel-plated tungsten electrode was joined to the metallized layer using an active metal braze. Further, the nickel electrode plated molybdenum electrode was connected to the tungsten electrode, and the nickel electrode was further connected to the molybdenum electrode to complete the electrode. The outside of these electrodes was covered with an insulating pipe 9 made of a mullite-alumina composite, and extended outside the chamber from a through hole provided at the bottom of the chamber. One end of the insulating pipe 9 was hermetically bonded to the ceramic substrate 1 using glass, and the other end was hermetically sealed to the chamber using an O-ring.

  Next, a counterbore process was performed on the substantially central portion of the joined body to provide a bottomed hole having a diameter of 3 mm and a depth of 8 mm, and the tip of the thermocouple was inserted therein. Furthermore, in order to join the cylindrical support, a counterbore process was performed at five predetermined positions of the joined body, and a tungsten bolt having a diameter of 4 mm was inserted therein and fixed by adhesion using glass. On the other hand, the cylindrical support body which provided the flange part at both ends was prepared, and the through-hole was provided in the position corresponding to the said volt | bolt of the one flange part. And after inserting the said volt | bolt through a corresponding through-hole, this bolt was fastened with the nut made from tungsten, and the cylindrical support body was fixed as shown in FIG. The bonded body was subjected to peripheral processing and formation of a wafer pocket for mounting a 12-inch wafer.

  Next, in order to accommodate the thermocouple, one end of an aluminum nitride pipe was joined to the counterbore part into which the thermocouple was inserted with glass, and the other end was extended from a through hole provided in the bottom of the chamber. . And between the outer peripheral surface of this pipe and the through-hole was airtightly sealed with an O-ring. The completed wafer holder was mounted in the chamber. A wafer thermometer was attached to the wafer pocket, and the heating element was energized and heated to 400 ° C. At this time, the temperature of the wafer holder was controlled based on the temperature measured by the thermocouple while the pressure in the chamber atmosphere was changed stepwise to vacuum, 1 Torr, 10 Torr, and 100 Torr.

  As a result, the temperature controllability is good with respect to the pressure change in the chamber, and the temperature control is stable regardless of the pressure change in the chamber (that is, not affected by the pressure). I found out that In addition, the temperature distribution in the wafer plane was within ± 2 ° C. under any pressure condition, and it was found that good thermal uniformity was obtained.

(Comparative Example 1)
For comparison with Example 1, the wafer holder used in Example 1 was drilled with a through hole A in a pipe made of aluminum nitride used for thermocouple protection, as shown in FIG. The end of the pipe was filled with resin B and sealed inside. The same experiment as in Example 1 was performed on this wafer holder. As a result, it took more than 5 minutes for the display temperature of the thermocouple to stabilize with respect to the pressure fluctuation in the chamber, and accordingly, the wafer temperature varied between about 390 to 410 ° C. and was not stable.

(Comparative Example 2)
For comparison with Example 1, a wafer holder as shown in FIG. In this wafer holder, a paste mainly composed of AlN—Y ₂ O is applied between a ceramic substrate and a cylindrical support, and bonded by hot pressing at 1700 ° C. for 2 hours and a pressure of 10 kg / cm ² . This was made in the same manner as the wafer holder of Example 1 except that the inside of the cylindrical support was an air atmosphere. The same experiment as in Example 1 was performed on this wafer holder.

  As a result, although it was possible to raise the temperature up to about 300 ° C. in the same manner as in Example 1, the inside of the cylindrical support was maintained in the air atmosphere, so when the temperature of the thermocouple was 300 ° C., the wafer The temperature of the thermometer was about 10 ° C. lower at the center than at the outer periphery. Furthermore, when the temperature of the thermocouple was around 380 ° C., the wafer holder was damaged starting from the vicinity of the joint between the ceramic substrate and the cylindrical support.

(Example 2)
In place of the ceramic substrate having the heating element and the high-frequency electrode circuit formed by applying and firing the tungsten paste shown in Example 1, a heating element and a ceramic substrate having a high-frequency electrode circuit each made of a coil and mesh made of molybdenum are produced. did. Specifically, aluminum nitride granules were prepared by spray drying, and a press body having a diameter of 320 mm and a thickness of 10 mm was first prepared by press molding. The press body was counterbored and a molybdenum coil serving as a heating element was attached. In addition, the molybdenum terminal for connecting with an electrode was connected to the both ends of the molybdenum coil.

Next, the press body was mounted on a mold, and aluminum nitride granules were inserted and press-molded. Subsequently, a molybdenum mesh equipped with a molybdenum terminal was placed on the obtained pressed body, and aluminum nitride granules were inserted and press-molded to produce a molded body. The formed body was degreased in a nitrogen atmosphere at 700 ° C., and then heated at a pressure of 200 kg / cm ² and 1800 ° C. for 2 hours with a hot press in a nitrogen atmosphere to produce an AlN ceramic substrate.

  Thereafter, a wafer holder as shown in FIG. 2 was produced in the same manner as in Example 1. The same experiment as in Example 1 was performed on this wafer holder. As a result, the same good results as in Example 1 were obtained.

(Comparative Example 3)
For comparison with Example 2, the wafer holder used in Example 2 was drilled with a through hole A in an aluminum nitride pipe used to protect the thermocouple, as shown in FIG. The end of the pipe was filled with resin B and sealed inside. The same experiment as in Example 2 was performed on this wafer holder. As a result, it took more than 5 minutes for the display temperature of the thermocouple to stabilize with respect to the pressure fluctuation in the chamber, and accordingly, the wafer temperature varied between about 390 to 410 ° C. and was not stable. That is, almost the same result as in Comparative Example 1 was obtained.

(Comparative Example 4)
For comparison with Example 2, a wafer holder as shown in FIG. 8 was produced. This wafer holder is the same as in Comparative Example 2, except that the ceramic substrate and the cylindrical support are chemically bonded, and that the inside of the cylindrical support is in an atmospheric atmosphere. It was produced in the same manner as the body. The same experiment as in Example 2 was performed on this wafer holder.

  As a result, it was possible to raise the temperature up to around 300 ° C. as in Example 1. However, since the inside of the cylindrical support was maintained in an air atmosphere, when the thermocouple temperature was 300 ° C., the temperature of the wafer thermometer was about 10 ° C. lower than the outer periphery. Furthermore, when the temperature of the thermocouple was around 380 ° C., the wafer holder was damaged starting from the vicinity of the joint between the ceramic substrate and the cylindrical support.

(Example 3)
A wafer holder as shown in FIG. 3 was produced. The wafer holder includes a first heating element embedded in an inner peripheral portion having a diameter of 250 mm or less and a second heating element embedded in an outer peripheral portion having a diameter of 250 to 320 mm and routed to the vicinity of the center portion. And the temperature of the region heated by the second heating element on the counterbore formed on the outside of the cylindrical support on the ceramic substrate. This was produced in the same manner as in Example 1 except that a thermocouple was installed. In FIG. 3, only two electrodes (conductors 8) for the heating element 102 are shown for simplicity, but actually there are four of the same shape.

  A wafer thermometer was mounted on the wafer holder, and the temperature was raised while monitoring the temperature of the thermocouples installed on the inner and outer peripheral parts so that the inner peripheral and outer peripheral parts would have a uniform temperature. As a result, at the time of 400 ° C., the temperature of the wafer thermometer could be controlled to ± 0.5 ° C. Further, when the pressure in the chamber was changed in the same manner as in Example 1, when the temperature was controlled only with the thermocouple inside the cylindrical support, a stable temperature was confirmed with a wafer thermometer as in Example 1. I was able to. At that time, the outputs of the two heating elements could be stabilized by fixing the ratio of these outputs based on the data obtained at 400 ° C.

Example 4
A wafer holder as shown in FIG. 4 was produced. The wafer holder includes a first heating element embedded in an inner peripheral portion having a diameter of 250 mm or less and a second heating element embedded in an outer peripheral portion having a diameter of 250 to 320 mm and routed to the vicinity of the center portion. And the temperature of the region heated by the second heating element on the counterbore formed on the outside of the cylindrical support on the ceramic substrate. This was produced in the same manner as in Example 3 except that a thermocouple was installed. In FIG. 4, for simplicity, only two electrodes (conductor 8) for the heating element 122 are shown, but actually there are four of the same shape.

  A wafer thermometer was mounted on the wafer holder, and the temperature was raised while monitoring the temperature of the thermocouples installed on the inner and outer peripheral parts so that the inner peripheral and outer peripheral parts would have a uniform temperature. As a result, at the time of 400 ° C., the temperature of the wafer thermometer could be controlled to ± 0.5 ° C. Further, when the pressure in the chamber was changed in the same manner as in Example 1, when the temperature was controlled only with the thermocouple inside the cylindrical support, a stable temperature was confirmed with a wafer thermometer as in Example 2. I was able to. At that time, the outputs of the two heating elements could be stabilized by fixing the ratio of these outputs based on the data obtained at 400 ° C.

(Comparative Example 5)
For comparison with Example 3, a wafer holder was produced in the same manner as in Example 3 except that the ceramic substrate and the cylindrical support were joined as in Comparative Example 2. And while confirming the temperature of two thermocouples, it heated up until the average temperature of the wafer thermometer became 400 degreeC, maintaining an inner peripheral part 20 degreeC higher than an outer peripheral part. Then, while gradually increasing the output of the outer peripheral heating element, the output of the inner peripheral heating element was reduced to adjust the output so that the wafer temperature was uniform. As a result, it was possible to adjust soaking up to 406 ° C. at the central part and 393 ° C. at the outer peripheral part of the wafer temperature. The wafer holder was damaged starting from the vicinity of the joint.

DESCRIPTION OF SYMBOLS 1 Ceramic substrate 2 Heat generating body 3 High frequency electrode circuit 4 Cylindrical support body 6 Bolt 7 Nut 8 Conductor 9 Insulating pipe 10 Sealing member 11 Temperature measuring element 12 Cylindrical body

Claims (3)

A wafer for a semiconductor manufacturing apparatus, comprising a substrate having an embedded heating element and made of a material mainly composed of aluminum nitride, and a cylindrical support that is mechanically coupled to and supports the substrate. A holding body,
A plurality of temperature measuring elements are installed on the substrate,
At least one of the plurality of temperature measuring elements is housed in a cylindrical body provided inside the support body and is isolated from the atmosphere inside the support body. The temperature measuring element is a wafer holder for a semiconductor manufacturing apparatus provided outside the support and in an atmosphere outside the support without being housed in another cylindrical body. The heating element is composed of a plurality , and at least one of the plurality of heating elements mainly heats the inner peripheral portion of the substrate, and at least one other one mainly heats the outer peripheral portion of the substrate. The wafer holder for a semiconductor manufacturing apparatus according to claim 1, wherein the plurality of temperature measuring elements are respectively installed on the substrate in correspondence with the heating elements that heat the inner peripheral portion and the outer peripheral portion, respectively. The wafer holder for a semiconductor manufacturing apparatus according to claim 1, wherein an inner side of the cylindrical body is an air atmosphere.

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