JP2005267931A - Heater unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heater unit of which a heater base plate support structure has high durability, having high reliability and evenness of heat, even if quenching is repeated. <P>SOLUTION: The heater unit has a structure supporting the heater base plate and a shield body for shielding the heat of the heater base body by supporting bodies. Through-holes are formed on the heater base plate, and the support bodies are inserted and fixed to the insertion hole. It is preferable to arrange cooling blocks between the heater unit and the heat-shielding body for improving quick cooling rate, and it is preferable that the difference of the coefficient of thermal expansion between that of supporting body and the heater base plate be 5×10<SP>-6</SP>/°C or lower. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention includes an etching apparatus, a sputtering apparatus, a plasma CVD apparatus, a low pressure plasma CVD apparatus, a metal CVD apparatus, an insulating film CVD apparatus, a low dielectric constant film (Low-K) CVD apparatus, an MOCVD apparatus, a degas apparatus, an ion implantation apparatus, The present invention relates to a heater unit used in a semiconductor manufacturing apparatus such as a coater developer.

  Conventionally, in a semiconductor manufacturing process, various processes such as a film formation process and an etching process are performed on a semiconductor substrate (wafer) that is an object to be processed. In a semiconductor manufacturing apparatus that performs processing on such a semiconductor substrate, a ceramic heater for holding the semiconductor substrate and heating the semiconductor substrate is used.

  Such a conventional ceramic heater is disclosed in, for example, Japanese Patent Laid-Open No. 4-78138. A ceramic heater disclosed in Japanese Patent Laid-Open No. 4-78138 is a ceramic heater portion in which a resistance heating element is embedded, installed in a container, and provided with a wafer heating surface, and the heater portion other than the wafer heating surface. And is connected to a resistance heating element and taken out of the container so as not to be substantially exposed to the internal space of the container. Electrode.

  In this invention, the contamination seen in the metal heater that is the previous heater and the improvement of the thermal efficiency are improved, but when the temperature distribution of the heater increases, the heater portion and the convex support portion Stress may concentrate on the joint and the heater may break.

  Japanese Patent Application No. 2002-163747 has proposed a heater unit having a cooling block for forcibly cooling a ceramic heater in order to shorten the manufacturing time in order to increase the productivity of the semiconductor. In this proposal, if a support structure similar to that of Patent Document 1 is used, the cooling block rapidly cools, so the risk of destruction of the joint between the heater portion and the convex support portion is even greater. .

  Further, instead of the convex support portion as in Patent Document 1, as shown in FIG. 7A, the front end of the support is processed with a male screw, the heater substrate is processed with a female screw, and the support is screwed into the heater substrate and fixed. There is also a way to do it. However, as shown in FIG. 7B, as the temperature rises and falls, the heater substrate may crack 20 and become unsupportable.

Semiconductor manufacturing is mass-produced by continuous operation, and competition for lower prices of products is conducted.Manufacturing equipment eliminates the above risks as much as possible, and has high reliability during long-time continuous operation. It is requested. Also, high temperature uniformity is required for the temperature distribution on the wafer heating surface.
Japanese Patent Laid-Open No. 04-078138 Japanese Patent Application No. 2002-163747

  The present invention has been made to solve the above problems. That is, an object of the present invention is to provide a heater unit that has a highly durable support structure for a heater substrate and that has high reliability and high heat uniformity even when rapid cooling is repeated.

  The heater unit of the present invention is a heater unit in which a heater substrate and the heater substrate are supported by a support, wherein a through hole is formed in the heater substrate, and the support is inserted and fixed in the through hole. It is characterized by being.

It is preferable to provide a cooling block in the heater unit because the cooling rate can be improved. The difference in thermal expansion coefficient between the support and the heater substrate is preferably 5 × 10 ⁻⁶ / ° C. or less. As a combination that provides such a difference in thermal expansion coefficient, the ceramics of the heater substrate is any one selected from the group consisting of aluminum nitride, silicon nitride, and silicon carbide, and the support is tungsten, It is preferably any one selected from the group consisting of molybdenum, Fe—Ni alloy, and Fe—Ni—Co alloy.

  The support preferably has a thermal conductivity of 50 W / mK or less, and the support is made of Fe—Ni—Co alloy, Fe—Ni alloy, titanium, chromium steel, Ti—Ni alloy, and stainless steel. It is preferably any one selected from the group.

  According to the present invention, it is possible to provide a heater unit in which the fixing between the heater substrate and the support is stable, and the reliability and heat uniformity are high. Furthermore, if a cooling block is provided, a cooling rate can be improved. A semiconductor manufacturing apparatus equipped with such a heater unit has a more uniform temperature distribution of the wafer than that of a conventional apparatus, has high reliability, and can improve productivity.

  An example of the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing a heater unit 1 of the present invention. The heater unit 1 supports a heater substrate 2 with a support 4 and is attached to a gantry 10 of a semiconductor manufacturing apparatus. An electrode 6 for supplying power to the heater and a temperature measuring means 7 are connected to the heater substrate.

  Moreover, you may attach the cooling block 5 to the heater unit 1 via the raising / lowering means 8 so that it can contact | abut or isolate | separate to a heater board | substrate. When the heater substrate is cooled, the heater substrate 2 can be rapidly cooled by bringing the cooling block 5 into contact with the heater substrate 2. Even with rapid cooling, with the structure of the present invention, the risk of the heater substrate being destroyed at the connecting portion between the heater substrate and the support is extremely reduced. Moreover, you may attach the heat shield 3 for interrupting the heat which generate | occur | produced with the heater. By attaching the heat shield, the heat diffusion of the heater is suppressed, and the power consumption can be suppressed. The heat shield 3 may be supported by the support 4.

  FIG. 2 is an enlarged view of a mounting portion between the heater substrate 2 and the support body 4. The support substrate is provided with a through hole 40, a front end portion is male threaded, and a stepped portion 43 is provided. 4 is inserted into the through hole and fixed with a nut 42. The heater substrate 2 is preferably provided with a counterbore portion 41 so that the nut 42 can be accommodated. At this time, it is preferable that the support and the nut are installed so as not to contact an object to be processed such as a wafer to be mounted. When the support or the nut is in contact with the object to be processed, the distance between the object to be processed and the heater substrate becomes non-uniform, and the temperature variation of the object to be processed may increase, which is not preferable.

The heat of the heater substrate escapes through the support. Since this heat escape inhibits the uniformity of the temperature of the heater substrate, the cross-sectional area of the support 4 is preferably small as long as the mechanical strength is not impaired, and is preferably 3 mm ² or more and 30 mm ² or less. If it is less than 3 mm ² , the mechanical strength is insufficient, so that it is difficult to sufficiently support the heater substrate and the heat shield. On the other hand, if it exceeds 30 mm ² , the amount of heat transfer will increase and the heat uniformity of the heater substrate will be inferior.

  Therefore, as shown in FIG. 3, it is preferable from the viewpoint of heat uniformity to provide a protruding portion 44 instead of the stepped portion 43 of the support 4. Further, as shown in FIG. 4, the protrusion 44 may be a ring 45 made of a known material. By doing in this way, the processing cost of a support body can be reduced.

  Further, as shown in FIG. 5, the tip of the support 4 can be processed with a protrusion 47, the support can be inserted from above the heater substrate, and fixed with a nut 46. As described above, the fixing method is not particularly limited as long as the heater substrate is provided with a through hole and the support body is inserted into the through hole and fixed. When the heat shield is also supported, for example, as shown in FIG. 6, the support 4 may be inserted into the through hole of the heat shield, fixed with the nut 42, and another support may be connected.

  Moreover, as shown in FIGS. 2-5, the ceramic heater board | substrate is pinched | interposed and fixed by the support body and the nut. When the thermal expansion coefficient of the support is smaller than that of the heater substrate, when the temperature of the heater substrate is increased, compressive stress due to the difference in thermal expansion coefficient is applied to the heater substrate. If the difference in thermal expansion coefficients is too large, the heater substrate may be destroyed or the support may be destroyed or deformed by this compressive stress.

On the contrary, if the thermal expansion coefficient of the support is large, the support expands as the temperature rises, and the fixation becomes loose, and the heater substrate moves due to external impact or vibration, and in some cases May destroy. Therefore, the difference in thermal expansion coefficient between the support and the heater substrate is preferably 5 × 10 ⁻⁶ / ° C. or less in the temperature range of 25 ° C. to 500 ° C. 2 × 10 ⁻⁶ / ° C. is more preferable.

The material of the heater substrate is preferably aluminum nitride or silicon carbide having high thermal conductivity if importance is attached to the uniformity of temperature distribution. If importance is placed on reliability, silicon nitride is preferable because it is strong and resistant to thermal shock. Thermal expansion coefficient of these ^ceramics, because it is 3.5x10 ^-6 ~5x10 -6 / ℃, the difference in thermal expansion coefficient in the temperature range of 25 ° C. to 500 ° C., or less 5x10 ^-6 / ° C. support The body is preferably any of tungsten, molybdenum, Fe—Ni alloy, and Fe—Ni—Co alloy. The support and the nut are preferably made of the same material, but any combination of these materials may be used.

  In addition, since the heat of the heater substrate escapes through the support and the temperature distribution of the heater substrate becomes non-uniform, in order to reduce the heat escape and make the heater substrate more uniform, the thermal conductivity of the support is The heat conductivity of the support is preferably 50 W / mK or less.

  Such a material is preferably any of Fe—Ni—Co alloy, Fe—Ni alloy, titanium, chromium steel, Ti—Ni alloy, and stainless steel. In this case as well, the support and the nut are preferably made of the same material, but any combination of these materials may be used.

  As the ceramic for the heater substrate, aluminum nitride (AlN) having high thermal conductivity and excellent corrosion resistance is suitable among the ceramics in view of the balance between performance and cost. Below, the manufacturing method of the heater substrate of this invention is explained in full detail in the case of AlN.

The raw material powder of AlN preferably has a specific surface area of 2.0 to 5.0 m ² / g. When the specific surface area is less than 2.0 m ² / g, the sinterability of aluminum nitride is lowered. On the other hand, if it exceeds 5.0 m ² / g, the aggregation of the powder becomes very strong, so that handling becomes difficult. Furthermore, the amount of oxygen contained in the raw material powder is preferably 2 wt% or less. When the amount of oxygen exceeds 2 wt%, the thermal conductivity of the sintered body decreases. The amount of metal impurities other than aluminum contained in the raw material powder is preferably 2000 ppm or less. When the amount of metal impurities exceeds this range, the thermal conductivity of the sintered body decreases. In particular, group IV elements such as Si and iron group elements such as Fe as metal impurities have a high effect of reducing the thermal conductivity of the sintered body, and therefore the content is preferably 500 ppm or less.

  Since AlN is a hardly sinterable material, it is preferable to add a sintering aid to the AlN raw material powder. The sintering aid to be added is preferably a rare earth element compound. The rare earth element compound reacts with the aluminum oxide or aluminum oxynitride existing on the surface of the aluminum nitride powder particles during the sintering to promote the densification of the aluminum nitride and the thermal conductivity of the aluminum nitride sintered body. Therefore, the thermal conductivity of the aluminum nitride sintered body can be improved.

  The rare earth element compound is preferably an yttrium compound that is particularly effective in removing oxygen. The addition amount is preferably 0.01 to 5 wt%. If it is less than 0.01 wt%, it is difficult to obtain a dense sintered body, and the thermal conductivity of the sintered body decreases. If it exceeds 5 wt%, a sintering aid exists at the grain boundaries of the aluminum nitride sintered body. Therefore, when used in a corrosive atmosphere, the sintering aid present at the grain boundaries is etched. , Cause degranulation and particles. Furthermore, the amount of the sintering aid added is preferably 1 wt% or less. If it is 1 wt% or less, the sintering aid is not present at the triple point of the grain boundary, so that the corrosion resistance is improved.

  As the rare earth element compound, an oxide, nitride, fluoride, stearic acid compound, or the like can be used. Of these, oxides are preferable because they are inexpensive and readily available. In addition, since the stearic acid compound has a high affinity with an organic solvent, when the aluminum nitride raw material powder and the sintering aid are mixed with the organic solvent, the mixing property is particularly preferable.

  Next, a predetermined amount of a solvent, a binder and, if necessary, a dispersant and a glaze are added to and mixed with the aluminum nitride raw material powder and the sintering aid powder. As the mixing method, ball mill mixing, ultrasonic mixing, or the like is possible. A raw material slurry can be obtained by such mixing.

  An aluminum nitride sintered body can be obtained by molding and sintering the obtained slurry. There are two types of methods, a cofire method and a post metallization method.

  First, the post metallization method will be described. Granules are prepared from the slurry by a technique such as spray drying. The granules are inserted into a predetermined mold and press-molded. At this time, the press pressure is desirably 9.8 MPa or more. When the pressure is less than 9.8 MPa, the strength of the molded body is often not sufficiently obtained, and is easily damaged by handling.

Although the density of a molded object changes with content of a binder, and the addition amount of a sintering auxiliary agent, it is preferable that it is 1.5 g / cm < ³ > or more. If it is less than 1.5 g / cm ³ , the distance between the raw material powder particles becomes relatively large, so that sintering does not proceed easily. Moreover, it is preferable that a molded object density is 2.5 g / cm < ³ > or less. If it exceeds 2.5 g / cm ³ , it will be difficult to sufficiently remove the binder in the molded body by the degreasing process in the next step. For this reason, it becomes difficult to obtain a dense sintered body as described above.

  Next, the molded body is heated in a non-oxidizing atmosphere to perform a degreasing treatment. When the degreasing treatment is performed in an oxidizing atmosphere such as the air, the surface of the AlN powder is oxidized, so that the thermal conductivity of the sintered body is lowered. As the non-oxidizing atmosphere gas, nitrogen or argon is preferable. The heating temperature for the degreasing treatment is preferably 500 ° C. or higher and 1000 ° C. or lower. When the temperature is less than 500 ° C., the binder cannot be sufficiently removed, and therefore excessive carbon remains in the laminated body after the degreasing treatment, which inhibits sintering in the subsequent sintering step. Further, at a temperature exceeding 1000 ° C., the amount of remaining carbon becomes too small, so that the ability of the oxide film present on the surface of the AlN powder to remove oxygen is lowered, and the thermal conductivity of the sintered body is lowered.

  Moreover, it is preferable that the carbon amount which remains in the molded object after a degreasing process is 1.0 wt% or less. If carbon exceeding 1.0 wt% remains, sintering is inhibited, and a dense sintered body cannot be obtained.

  Next, sintering is performed. Sintering is performed at a temperature of 1700 to 2000 ° C. in a non-oxidizing atmosphere such as nitrogen or argon. At this time, it is preferable that the moisture contained in the atmosphere gas such as nitrogen used is −30 ° C. or less in terms of dew point. In the case of containing more moisture than this, AlN reacts with moisture in the atmospheric gas during sintering to form oxynitrides, which may reduce the thermal conductivity. Moreover, it is preferable that the oxygen amount in atmospheric gas is 0.001 vol% or less. If the amount of oxygen is large, the surface of AlN may be oxidized and the thermal conductivity may be reduced.

  Furthermore, a boron nitride (BN) compact is suitable for the jig used during sintering. Since this BN compact has sufficient heat resistance to the sintering temperature and has a solid lubricating property on its surface, the friction between the jig and the laminate when the laminate shrinks during sintering. Therefore, a sintered body with less distortion can be obtained.

  The obtained sintered body is processed as necessary. When screen-printing the conductive paste in the next step, the surface roughness of the sintered body is preferably 5 μm or less in terms of Ra. If the thickness exceeds 5 μm, defects such as pattern bleeding and pinholes are likely to occur when a circuit is formed by screen printing. The surface roughness Ra is more preferably 1 μm or less.

  When polishing the above surface roughness, it is natural to screen print on both sides of the sintered body, but even when screen printing is performed only on one side, the surface opposite to the screen printed side is also polished. It is better to apply. When only the surface to be screen printed is polished, the sintered body is supported by the surface that is not polished during screen printing. At this time, there may be protrusions and foreign matters on the surface that has not been polished, so that the fixing of the sintered body becomes unstable, and the circuit pattern may not be drawn well by screen printing.

  At this time, the parallelism of both processed surfaces is preferably 0.5 mm or less. When the parallelism exceeds 0.5 mm, the thickness of the conductive paste may vary greatly during screen printing. The parallelism is particularly preferably 0.1 mm or less. Furthermore, the flatness of the screen printing surface is preferably 0.5 mm or less. Even in the case of flatness exceeding 0.5 mm, the variation in the thickness of the conductive paste may increase. A flatness of 0.1 mm or less is particularly suitable.

  A conductive paste is applied by screen printing to the polished sintered body to form an electric circuit. The conductive paste can be obtained by mixing a metal powder and, if necessary, an oxide powder, a binder and a solvent. The metal powder is preferably tungsten, molybdenum or tantalum from the viewpoint of matching the thermal expansion coefficient with ceramics.

In order to increase the adhesion strength with AlN, an oxide powder can also be added. The oxide powder is preferably an oxide of a IIa group element or a IIIa group element, Al ₂ O ₃ , SiO ₂ or the like. In particular, yttrium oxide is preferable because it has very good wettability to AlN. The addition amount of these oxides is preferably 0.1 to 30 wt%. When the content is less than 0.1 wt%, the adhesion strength between the metal layer, which is the formed electric circuit, and AlN is lowered. Moreover, when it exceeds 30 wt%, the electrical resistance value of the metal layer which is an electric circuit will become high.

  The thickness of the conductive paste is preferably 5 μm or more and 100 μm or less after drying. When the thickness is less than 5 μm, the electrical resistance value becomes too high and the adhesion strength also decreases. Moreover, also when exceeding 100 micrometers, adhesive strength falls.

  In addition, when the circuit pattern to be formed is a heater circuit (a heating element circuit), the pattern interval is preferably 0.1 mm or more. If the interval is less than 0.1 mm, when a current is passed through the heating element, a leakage current is generated depending on the applied voltage and temperature, resulting in a short circuit. In particular, when used at a temperature of 500 ° C. or higher, the pattern interval is preferably 1 mm or more, more preferably 3 mm or more.

  Next, the conductive paste is degreased and fired. Degreasing is performed in a non-oxidizing atmosphere such as nitrogen or argon. The degreasing temperature is preferably 500 ° C. or higher. If the temperature is less than 500 ° C., the binder in the conductive paste is not sufficiently removed, and carbon remains in the metal layer, and metal carbide is formed when baked, so that the electrical resistance value of the metal layer becomes high.

  Firing is preferably performed at a temperature of 1500 ° C. or higher in a non-oxidizing atmosphere such as nitrogen or argon. When the temperature is less than 1500 ° C., the particle growth of the metal powder in the conductive paste does not proceed, so that the electric resistance value of the fired metal layer becomes too high. The firing temperature should not exceed the sintering temperature of the ceramic. When the conductive paste is fired at a temperature exceeding the sintering temperature of the ceramic, the sintering aid contained in the ceramic begins to evaporate, and further, the grain growth of the metal powder in the conductive paste is promoted, and the ceramic and the metal layer. The adhesion strength of the is reduced.

Next, in order to ensure the insulation of the formed metal layer, an insulating coat can be formed on the metal layer. The material of the insulating coat is not particularly limited as long as the reactivity with the electric circuit is small and the difference in thermal expansion coefficient from AlN is 5.0 × 10 ⁻⁶ / K or less. For example, crystallized glass or AlN can be used. These materials can be formed, for example, by pasting them into a paste, performing screen printing with a predetermined thickness, degreasing as necessary, and firing at a predetermined temperature. For example, in the case of AlN, a predetermined amount of Group IIa element or Group IIIa element oxide or carbonate is added to the AlN powder as a sintering aid, mixed, and a binder or solvent is added thereto, and the paste is used as a paste. It can apply | coat on the said metal layer by screen printing.

  At this time, the amount of the sintering aid to be added is preferably 0.01 wt% or more. If it is less than 0.01 wt%, the insulating coating will not be densified, and it will be difficult to ensure the insulating properties of the metal layer. Moreover, it is preferable that the amount of sintering aid does not exceed 20 wt%. If it exceeds 20 wt%, an excessive sintering aid penetrates into the metal layer, and the electrical resistance value of the metal layer may change. Although there is no restriction | limiting in particular in the thickness to apply | coat, It is preferable that it is 5 micrometers or more. This is because if it is less than 5 μm, it is difficult to ensure insulation.

  Moreover, it is also possible to use a mixture or alloy of silver, palladium, platinum or the like as the conductive paste. Since these metals increase the volume resistivity of the conductor by adding palladium or platinum to the silver content, the addition amount may be adjusted according to the circuit pattern. Moreover, since these additives have an effect of preventing migration between circuit patterns, it is preferable to add 0.1 parts by weight or more with respect to 100 parts by weight of silver.

  A metal oxide is preferably added to these metal powders in order to ensure adhesion with AlN. For example, aluminum oxide, silicon oxide, copper oxide, boron oxide, zinc oxide, lead oxide, rare earth oxide, transition metal element oxide, alkaline earth metal oxide, or the like can be added. The addition amount is preferably 0.1 wt% or more and 50 wt% or less. If the content is less than this, the adhesion with aluminum nitride is lowered, which is not preferable. Further, if the content is higher than this, sintering of metal components such as silver is inhibited, which is not preferable.

  These metal powders and inorganic powders are mixed, an organic solvent or a binder is further added to form a paste, and a circuit can be formed by screen printing as described above. In this case, the formed circuit pattern is baked in a temperature range of 700 ° C. to 1000 ° C. in an inert gas atmosphere such as nitrogen or in the air.

  Furthermore, in this case, in order to ensure insulation between circuits, crystallized glass, glaze glass, an organic resin, or the like is applied, and the insulating layer can be formed by baking or curing. As the glass type, borosilicate glass, lead oxide, zinc oxide, aluminum oxide, silicon oxide, and the like can be used. An organic solvent or a binder is added to these powders to form a paste, which is applied by screen printing. Although there is no restriction | limiting in particular in the thickness applied, It is preferable that it is 5 micrometers or more. This is because if it is less than 5 μm, it is difficult to ensure insulation. The firing temperature is preferably lower than the temperature at which the circuit is formed. Baking at a higher temperature than the above circuit baking is not preferable because the resistance value of the circuit pattern changes greatly.

  Next, a ceramic sintered body can be further laminated as necessary. Lamination is preferably performed via a bonding agent. The bonding agent is obtained by adding a IIa group element compound or a group IIIa element compound and a binder or a solvent to aluminum oxide powder or aluminum nitride powder, and applying the paste to the bonding surface by a method such as screen printing. Although there is no restriction | limiting in particular in the thickness of the bonding agent to apply | coat, it is preferable that it is 5 micrometers or more. When the thickness is less than 5 μm, bonding defects such as pinholes and bonding unevenness easily occur in the bonding layer.

  The ceramic sintered body coated with the bonding agent is degreased at a temperature of 500 ° C. or higher in a non-oxidizing atmosphere. Thereafter, the ceramic substrates to be laminated are superposed, a predetermined load is applied, and the ceramic sintered bodies are joined together by heating in a non-oxidizing atmosphere. The load is preferably 5 kPa or more. When the load is less than 5 kPa, sufficient bonding strength cannot be obtained, or the above-described bonding defect is likely to occur.

  The heating temperature for bonding is not particularly limited as long as the ceramic sintered bodies are sufficiently adhered to each other through the bonding layer, but is preferably 1500 ° C. or higher. If it is less than 1500 degreeC, sufficient joint strength is hard to be obtained and it will be easy to produce a joint defect. Nitrogen or argon is preferably used for the non-oxidizing atmosphere during the degreasing and bonding.

  As described above, a ceramic laminated sintered body serving as a heater substrate can be obtained. For example, if the electric circuit is a heater circuit without using a conductive paste, for example, a molybdenum wire (coil), an electrostatic adsorption electrode or an RF electrode, a mesh of molybdenum or tungsten (network) It is also possible to use.

  In this case, the molybdenum coil and mesh are incorporated in the AlN raw material powder, and can be manufactured by a hot press method. The hot press temperature and atmosphere may be in accordance with the sintering temperature and atmosphere of AlN, but the hot press pressure is preferably 0.98 MPa or more. If it is less than 0.98 MPa, a gap may be formed between the molybdenum coil or mesh and AlN, and the performance of the heater may not be achieved.

  Next, the cofire method will be described. The raw material slurry described above is formed into a sheet by a doctor blade method. Although there is no restriction | limiting in particular regarding sheet shaping | molding, As for the thickness of a sheet | seat, 3 mm or less is preferable after drying. If the thickness of the sheet exceeds 3 mm, the amount of drying shrinkage of the slurry increases, so that the probability of cracking in the sheet increases.

  A metal layer to be an electric circuit having a predetermined shape is formed on the above-described sheet by applying a conductive paste by a technique such as screen printing. The same conductive paste as that described in the post metallization method can be used. However, in the cofire method, there is no problem even if the oxide powder is not added to the conductive paste.

  Next, the sheet on which the circuit is formed and the sheet on which the circuit is not formed are stacked. In the laminating method, each sheet is set at a predetermined position and overlapped. At this time, a solvent is applied between the sheets as necessary. In the state of being overlaid, heat as necessary. When heating, it is preferable that heating temperature is 150 degrees C or less. When heated to a temperature exceeding this, the laminated sheets are greatly deformed. Then, the stacked sheets are integrated by applying pressure. The applied pressure is preferably in the range of 1 to 100 MPa. If the pressure is less than 1 MPa, the sheets may not be sufficiently integrated and may peel during the subsequent steps. Further, when a pressure exceeding 100 MPa is applied, the deformation amount of the sheet becomes too large.

  This laminated body is degreased and sintered in the same manner as the above-described post metallization method. The degreasing treatment and sintering temperature, the amount of carbon, etc. are the same as in the post metallization method. When the conductive paste is printed on a sheet as described above, a heater circuit, an electrostatic adsorption electrode, etc. are printed on a plurality of sheets, respectively, and these are stacked to facilitate an energizing heat generating heater having a plurality of electric circuits. It is also possible to create it. In this way, a ceramic laminated sintered body serving as a heater substrate can be obtained.

  In addition, when an electric circuit such as a heating element circuit is formed in the outermost layer of the ceramic laminate, in order to protect the electric circuit and ensure insulation, the electric circuit An insulating coating can be formed thereon.

  The obtained ceramic laminated sintered body is processed as necessary. Usually, in the sintered state, the accuracy required for a semiconductor manufacturing apparatus is often not reached. As for the processing accuracy, for example, the flatness of the workpiece mounting surface is preferably 0.5 mm or less, more preferably 0.1 mm or less. When the flatness exceeds 0.5 mm, a gap is likely to be formed between the workpiece and the heater substrate, and the heat of the heater substrate is not transmitted uniformly to the workpiece, and the temperature unevenness of the workpiece is likely to occur. Become.

  The surface roughness of the heater substrate is preferably 5 μm or less in terms of Ra. When the Ra exceeds 5 μm, AlN degranulation may increase due to friction between the heater substrate and the wafer. At this time, the shed particles become particles, which adversely affects processing such as film formation and etching on the wafer. Further, the surface roughness is preferably 1 μm or less in terms of Ra. As described above, the heater substrate body can be manufactured.

  Next, an electrode is attached to the heater substrate. Attachment can be performed by a known method. For example, it is only necessary to perform counterbore processing from the opposite side of the wafer holding surface of the heater substrate to the electric circuit, and to apply metallization to the electric circuit or directly connect an electrode such as molybdenum or tungsten using an active metal brazing without metallization. . Thereafter, the electrode can be plated as necessary to improve oxidation resistance. In this way, a heater substrate can be manufactured.

  Furthermore, the heater unit of the present invention can be obtained by supporting the heater substrate and the heat shield with a support.

Mix 100 parts by weight of aluminum nitride (AlN) powder and 0.6 parts by weight of yttrium stearate powder in terms of yttrium, mix 10 parts by weight and 5 parts by weight, respectively, using polyvinyl butyral as a binder and dibutyl phthalate as a solvent. The granules were prepared by spray drying, press-molded, degreased in a nitrogen atmosphere at 700 ° C., and sintered at 1850 ° C. in a nitrogen atmosphere to prepare an aluminum nitride sintered body. The aluminum nitride powder used had an average particle size of 0.6 μm and a specific surface area of 3.4 m ² / g. The aluminum nitride sintered body was processed to have a diameter of 330 mm and a thickness of 12 mm. The thermal expansion coefficient of this AlN sintered body was 4.5 × 10 ⁻⁶ / ° C., and the thermal conductivity was 170 W / mK.

Also, a W paste was prepared using 100 parts by weight of W powder having an average particle size of 2.0 μm, 1 part by weight of Y ₂ O ₃ , 5 parts by weight of ethyl cellulose as a binder, and butyl carbitol as a solvent. did. A pot mill and three rolls were used for mixing. The W paste was screen-printed to form a heating element circuit pattern on the processed aluminum nitride sintered body. Then, it degreased in 900 degreeC and nitrogen atmosphere, and baked at 1800 degreeC in nitrogen atmosphere.

A ZnO—B ₂ O ₃ —Al ₂ O ₃ glass paste was applied to the surface on which the heating element circuit pattern was formed, applied to a thickness of 100 μm, excluding the power feeding portion, and baked at 700 ° C. in a nitrogen atmosphere. . In addition, a tungsten terminal was attached to the power feeding portion with a gold solder, and a nickel electrode was screwed to the tungsten terminal to complete a heater substrate.

  Moreover, the thing of the bottomed cylindrical shape (radiation factor 0.18) made from stainless steel was prepared as a heat shield. The height of the inner surface was 31 mm, the inner diameter was 333 mm, the side surface thickness was 1.5 mm, and the bottom surface thickness was 3 mm.

  In addition, two pure aluminum plates having a diameter of 330 mm and a thickness of 5 mm were prepared as cooling blocks. The thermal conductivity of the pure aluminum plate is 200 W / mK. A flow path for flowing a cooling medium having a width of 5 mm and a depth of 3 mm was formed on one of the sheets by machining. Further, a groove having a width of 2 mm and a depth of 1 mm for inserting an O-ring was formed on the outer periphery of the flow path. In addition, through holes were formed at the entrance and exit of the cooling medium. These two aluminum plates were fixed with screws by inserting an O-ring.

  As shown in FIG. 1, the heater substrate 2, the heat shield 3, and the cooling block 5 are supported by a columnar support 4 made of an Fe—Ni—Co alloy and having a diameter of 3 mm, and fixed to the apparatus base 10. installed. Three support bodies were equally arranged on a concentric circle. In addition, the bottom of the heat shield and the cooling block were provided with through holes for inserting the power supply wiring 6, the temperature measuring means 7 and the support 4. The bottom of the heat shield was also provided with a through-hole for inserting lifting means 8 such as an air cylinder for lifting the cooling block. The distance between the device mount and the container was 30 mm, and the distance between the container and the heater substrate was 24 mm. The nut material was also made of Fe-Ni-Co alloy.

  The heater substrate and the support were fixed in a shape as shown in FIG. The support had a diameter of 5 mm, and an M3 screw was formed at the fixing portion with the nut. Further, as shown in FIG. 6, the heat shield and the support are fixed by forming a through hole through which the M3 screw passes through the heat shield, forming the M3 screw at the tip of the support, Fixed with.

  For comparison, as shown in FIG. 7 (a), the tip of a cylindrical support 4 made of an Fe-Ni-Co alloy and having a diameter of 3 mm is threaded with M3. A heater unit attached with a female thread was also prepared. The heat shield and the support were attached in the same manner as in the previous example.

  A temperature cycle test was carried out using the heater unit prepared as described above. First, the temperature is raised to 300 ° C. in 10 minutes, held at 300 ° C. for 2 minutes, then cooled to 80 ° C. in about 20 minutes by natural air cooling, and then heated up to 300 ° C. in 10 minutes again. The number of times until the heater unit broke was examined. Further, after holding at 300 ° C. for 2 minutes, the cooling block in which the cooling water is flowed is brought into contact with the heater substrate, and is cooled to 80 ° C. in 8 minutes by forced cooling. A forced cooling temperature cycle test in which the temperature was raised in minutes was also conducted.

  During the cycle test, a 12-inch wafer thermometer was mounted on the heater substrate so that the temperature distribution could be measured. In the heater unit of the present invention, the temperature distribution did not occur more than 1000 times during the 1000 cycle tests both in the temperature cycle test without forced cooling and in the forced cooling temperature cycle test, and a good temperature distribution was maintained.

  On the other hand, in the conventional heater unit, without forced cooling, an abnormality was observed in the temperature distribution at the 775th time, and when the cycle test was interrupted and examined, there was a crack at one location of the heater substrate support portion. It has occurred. In the forced cooling temperature cycle test, an abnormality occurred in the temperature distribution at the 553th time, and a crack was also generated in the heater substrate.

In addition to the AlN heater substrate manufactured in Example 1, heater substrates made of silicon nitride and silicon carbide were prepared. The silicon nitride heater substrate is obtained by adding 3 wt% yttria (Y ₂ O ₃ ) and 2 wt% alumina (Al ₂ O ₃ ) as a sintering aid to silicon nitride (Si ₃ N ₄ ) powder, A binder was added, dispersed and mixed, and granules were produced by spray drying, and then the sintering conditions were 1650 ° C. in a nitrogen atmosphere for 4 hours. After that, 10 weight% of borosilicate glass with Ag 70 weight Pd as 20 weight glass component is added, and further a binder solvent is added in the same manner as in the case of the AlN heater, a paste is prepared, screen-printed, and then baked at 850 ° C. in the atmosphere. Thereafter, an insulating coat was applied in the same manner as the AlN heater to produce a heater. This Si ₃ N ₄ heater substrate had a thermal expansion coefficient of 3.5 × 10 ⁻⁶ / ° C. and a thermal conductivity of 25 W / mK.

In addition, the silicon carbide heater substrate is prepared by adding 2 wt% boron carbide (B ₄ C) and 1 wt% carbon (C) as a sintering aid to silicon carbide (SiC) powder, and further adding a binder. The mixture was dispersed and mixed, and the granules were prepared by spray drying. The granules were prepared in the same manner as the AlN heater substrate except that the sintering conditions were 2000 ° C. in an argon atmosphere for 7 hours. This SiC heater substrate had a thermal expansion coefficient of 4.0 × 10 ⁻⁶ / ° C. and a thermal conductivity of 100 W / mK.

  A heater unit was prepared in the same manner as in Example 1 except that the materials of the support and nut were changed to those shown in Tables 1 to 3, and the forced cooling temperature cycle test was performed 1000 times in the same manner as in Example 1. Further, the variation in temperature distribution during holding at 300 ° C. was measured as the difference between the maximum temperature and the minimum temperature of the wafer thermometer. These results are shown in Tables 1-3. Table 1 shows an AlN heater substrate, Table 2 shows an Si3N4 heater substrate, and Table 3 shows an SiC heater substrate. The difference in thermal expansion coefficient in the table indicates the difference between the thermal expansion coefficient of the heater substrate used and the thermal expansion coefficient of the support.

As can be seen from Tables 1 to 3, when the difference in thermal expansion coefficient is 5 × 10 ⁻⁶ / ° C. or less, no damage occurs in 1000 temperature cycle tests, and the reliability is excellent. However, SiC and zirconia are ceramics, and the cost of processing a male screw is higher than that of metal.

  Further, when the thermal conductivity of the support is 50 W / mK or less, the temperature distribution can be within 1% regardless of the material of the heater substrate. Further, when the heater substrate is made of AlN, the temperature distribution can be within 0.4% if the thermal conductivity of the support is 20 W / mK or less.

  According to the present invention, it is possible to provide a heater unit in which the fixing between the heater substrate and the support is stable, and the reliability and heat uniformity are high. Furthermore, if a cooling block is provided, a cooling rate can be improved. A semiconductor manufacturing apparatus equipped with such a heater unit has a more uniform temperature distribution of the wafer than that of a conventional apparatus, has high reliability, and can improve productivity.

The cross-sectional schematic diagram of the heater unit of this invention is shown. An example of a principal part section schematic diagram of a heater unit of the present invention is shown. The other example of the principal part cross-sectional schematic diagram of the heater unit of this invention is shown. The other example of the principal part cross-sectional schematic diagram of the heater unit of this invention is shown. The other example of the principal part cross-sectional schematic diagram of the heater unit of this invention is shown. The other example of the principal part cross-sectional schematic diagram of the heater unit of this invention is shown. The cross-sectional schematic diagram of the conventional heater unit is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heater unit 2 Heater board 3 Heat shield 4 Support body 5 Cooling block 6 Electrode 7 Temperature measuring means 8 Lifting means 10 Device mount 20 Crack 40 Through-hole 41 Counterbore part 42 Nut 43 Step part 44 Projection part 45 C ring 46 Nut 47 protrusion

Claims (4)

  In a heater unit composed of a ceramic heater substrate and a support that supports the ceramic heater substrate, a through hole is formed in the ceramic heater substrate, and the support is inserted and fixed in the through hole. A featured heater unit.   The heater unit according to claim 1, wherein the heater unit includes a cooling block for cooling the ceramic heater substrate. 3. The heater unit according to claim 1, wherein a difference in thermal expansion coefficient between the support and the ceramic heater substrate is 5 × 10 ⁻⁶ / ° C. or less. The heater unit according to claim 1 or 2, wherein the support has a thermal conductivity of 50 W / mK or less.

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