JP5381879B2 - Wafer heating heater unit and semiconductor manufacturing apparatus equipped with the same - Google Patents

Description

  The present invention relates to a wafer heating heater unit used in a semiconductor manufacturing apparatus. In particular, the present invention relates to a heater unit for heating a wafer that is excellent in rapid temperature rise and heat uniformity and excellent in reliability.

  In a semiconductor manufacturing process, various processes such as a film forming process and an etching process are performed on a semiconductor wafer which is an object to be processed. When it is necessary to heat the wafer, the wafer is placed on the wafer heating heater unit and subjected to a predetermined heat treatment. Examples thereof include a coater developer used for wafer photolithography, a wafer prober for semiconductor inspection, and a CVD apparatus for film formation.

  Among these, in the photolithography process for forming a resist film on the wafer, the wafer is washed, heated, dried, cooled, and then coated with a resist film on the wafer surface, and the wafer is applied to the heater unit in the photolithography processing apparatus. After mounting and drying, processing such as exposure and development is performed.

  Regarding the processing of wafers in these semiconductor manufacturing apparatuses, it is required to finish the processing in as short a time as possible in order to improve the throughput. Also, when the wafer is heated, the wafer is mounted on the heater unit, subjected to heat treatment, and then removed from the heater unit for transfer to the next process. Thermal properties are required. In addition, when the temperature condition of the heater is changed, for example, when the temperature is raised or lowered, it is necessary to quickly set the heater temperature. In addition, reliability is required for the heater to be used.

  For example, Patent Document 1 discloses a heating body for heating a wafer, which includes a heater provided with a heating element and a soaking plate via a heat insulating layer. In Patent Document 1, when the heating element is a metal foil, the metal foil is sandwiched between heat-resistant resins, for example, and the resin sandwiched between the metal foils is fixed between the heater substrate and the heat equalizing plate via a heat insulating layer. It is disclosed.

  As in Patent Document 1, when a metal foil heating element is sandwiched between heat-resistant resins and sandwiched between a heater substrate and a soaking plate via a heat insulating layer, the resin sandwiched between the metal foils is a portion where the metal foil is present. Then, the thickness is reduced as compared with a portion where no metal foil is present. For this reason, in the portion where the metal foil does not exist, a gap is likely to be generated between the heater substrate or the soaking plate, and the heat generated in the metal foil by this gap is uniformly conducted to the heater substrate and the soaking plate. In some cases, the soaking property may be impaired.

  In addition, when the metal foil generates heat, both the metal foil and the heat insulation layer rise in temperature. However, when the metal foil and the heat insulation layer have different thermal expansion coefficients, the metal foil and the heat insulation layer have different amounts of thermal expansion. When the heat insulating layer is bonded, the heating body is deformed due to the difference in thermal expansion amount, and warpage or the like occurs. For this reason, the adhesion of the heater substrate, the heating element, and the soaking plate is impaired, so that the soaking property is greatly deteriorated, and when these are mechanically fixed, the fixing portion may be damaged. It was.

  Furthermore, even when the cooling module is in contact with the soaking plate, there is a problem that if there is a gap between the cooling module and the soaking plate, the cooling of the gap becomes slow and temperature unevenness is likely to occur. To do.

JP 2008-118080 A

  The present invention has been made to solve the above problems. That is, an object of the present invention is to provide a wafer heating heater unit excellent in heat uniformity and reliability and a semiconductor manufacturing apparatus equipped with the same.

The heater unit for heating a wafer according to the present invention has a mounting table having a wafer mounting surface, a resistance heating unit on a surface opposite to the wafer mounting surface, and a support plate for supporting the mounting table and the resistance heating unit. The resistance heating unit includes a heating element and a plurality of insulating layers sandwiching the heating element. A groove is formed in at least one layer of the insulating layer, and the heating element is accommodated in the groove. are sandwiched by another insulating layer Te, the insulating layer each other have a part that is not adhered to each other, the thickness of the heating element is equal to or greater than the depth of the groove.

  It is preferable that the insulating layers are not bonded to each other. Moreover, it is preferable that the mounting table, the resistance heating unit, and the support plate are mechanically coupled. The groove of the insulating layer is preferably formed by an etching process.

  A semiconductor manufacturing apparatus equipped with such a wafer heating heater unit can be excellent in heat uniformity, reliability, and throughput.

  ADVANTAGE OF THE INVENTION According to this invention, the heater unit for wafer heating excellent in soaking | uniform-heating property and reliability can be provided.

The schematic diagram of the cross-sectional structure of the heater unit for wafer heating of this invention is shown. The other schematic diagram of the cross-sectional structure of the heater unit for wafer heating of this invention is shown. The other schematic diagram of the cross-sectional structure of the heater unit for wafer heating of this invention is shown. The schematic diagram of the cross-section of the insulating layer of the heater unit for wafer heating of this invention is shown. The schematic diagram of the cross-section of the insulating layer of the heater unit for wafer heating of a comparative example is shown. The schematic diagram of the cross-section of the insulating layer of the heater unit for wafer heating of a comparative example is shown. The schematic diagram of the cross-section of the heater unit for wafer heating of a comparative example is shown. The other schematic diagram of the cross-sectional structure of the heater unit for wafer heating of a comparative example is shown.

  Referring to FIG. 1, a wafer heating heater unit of the present invention has a mounting table 1 having a wafer mounting surface 10 and a resistance heating unit 2 on the surface of the mounting table opposite to the wafer mounting surface. The resistance heating unit 2 includes a heating element 21 and a plurality of insulating layers 22 sandwiching the heating element, and at least the insulating layer is included in the mounting table and the support plate 3 that supports the resistance heating unit. Grooves are formed in one layer, and the insulating layers have portions that are not bonded to each other.

  The heating element 21 and the insulating layer 22 are not bonded. When the heating element is energized and raised to a predetermined temperature, the temperature of the insulating layer also rises. Since the heating element and the insulating layer are made of different materials, they have different coefficients of thermal expansion. For this reason, the amount of thermal expansion accompanying the temperature rise differs between the heating element and the insulating layer. When the heating element and the insulating layer are bonded, the resistance heating unit is deformed due to the difference in the amount of thermal expansion, and warping or the like occurs, so that the adhesion between the mounting table, the resistance heating unit, and the support plate is impaired, so Thermal properties are greatly deteriorated. For this reason, a heat generating body and an insulating layer do not adhere.

  Further, it is necessary to have a portion where the insulating layers do not adhere to each other. The insulating layers are preferably not bonded at all, but may be partially bonded. The insulating layer can be bonded using, for example, an adhesive.

  When the insulating layers are bonded over the entire surface, for example, when a wafer at room temperature is placed on the placement surface while the heater unit for heating the wafer is heated to a predetermined temperature, the temperature of the placement surface is once lowered. The insulating layer on the side shrinks more than the insulating layer on the support plate side. When contracted, the central portion of the resistance heating unit is deformed (warped) in a direction away from the mounting table, the adhesion between the mounting table and the resistance heating unit is deteriorated, and the thermal uniformity is deteriorated temporarily but.

  In addition, when a cooling module (to be described later) is brought into contact with the support plate, the insulating layer on the support plate side is further contracted, so that it deforms in the opposite direction to the above, and the adhesion between the mounting table and the resistance heating unit also deteriorates. , Soaking becomes worse.

  If there is a portion where the insulating layers are not bonded to each other as in the present invention, it is possible to prevent the above-described deterioration in heat uniformity.

  In other words, the heat shrinkage amount or thermal expansion amount of the insulating layer is absorbed by the portion where the mounting table side and the support plate side are not bonded to prevent the resistance heating unit from being deformed, and the mounting table and the support plate are not deformed. Can be prevented.

  Since the insulating layer is made of the same material on the mounting table side and the support plate side, there is only a difference in thermal expansion amount or thermal contraction amount due to a temperature difference. Since it is smaller than the difference, if there is a part that is not partially bonded, the difference in thermal expansion or the difference in thermal shrinkage can be absorbed.

  For this reason, the insulating layers may be partially bonded. For example, the heating element can be sandwiched between two insulating layers, and the vicinity of the central portion of the insulating layer and the four outer peripheral portions can be fixed with an adhesive. By partially adhering the insulating layer, it is possible to prevent the heating element and the insulating layer from being displaced during assembly.

  It is preferable that the insulating layers do not adhere at all as shown in FIG. If the adhesive heating unit is not bonded at all, the deformation of the resistance heating unit is reduced, so that the transient thermal uniformity during temperature rise and fall is improved. Also, the cooling rate can be increased.

  As shown in FIG. 4, groove processing can be performed on one side of the insulating layer 22, the heating element can be inserted into the groove, and then covered with an insulating layer that has not been grooved. It is also possible to perform groove processing on the insulating layer on the covering side. However, when groove processing is performed on both insulating layers, it is necessary to align the groove of the other insulating layer after inserting the heating element into the groove of one insulating layer, so the process becomes complicated. Therefore, it is preferable to perform groove processing only on the insulating layer on one side.

  There is no particular limitation on the method for forming the groove in the insulating layer. For example, there are methods such as chemical etching, sand blasting, or press molding. However, in sandblasting, it is difficult to control the depth of the groove, and as shown in FIG. 5, the surface roughness in the groove becomes relatively rough, which hinders heat conduction between the insulating layer and the heating element. This is not preferable.

  When the groove is press-molded, as shown in FIG. 6, the surface opposite to the press surface of the insulating layer has a convex shape, so that the contact between the insulating layer and the mounting table or the support plate is uniform over the entire surface. This is not preferable because heat transfer is reduced and heat uniformity is deteriorated.

  Etching is most preferable because not only can pattern formation be performed freely by photolithography, but also the depth of the groove can be controlled relatively easily by controlling the etching time.

  The depth of the groove formed in the insulating layer is preferably thinner (shallow) than the thickness of the heating element to be inserted. The resistance heating unit is sandwiched between the mounting table and the support plate, but when the thickness of the heating element is thinner than the depth of the groove, a gap is formed between the heating element and the insulating layer, so that heat conduction is inhibited. This is not preferable because it adversely affects heat uniformity, temperature rise rate, cooling rate, transient heat uniformity, and the like.

  If the thickness of the heating element is greater than the depth of the groove, the heating element and the insulating layer are in close contact with each other, so that good heat conduction can be realized. In this case, a gap may be formed between the insulating layers, but since the insulating layer has a lower thermal conductivity than the heating element, the influence on the heat uniformity is relatively small.

  The thickness of the heating element and the depth of the groove are preferably the same, or the heating element is preferably about 20 μm thick. If the thickness of the heating element is increased to more than 50 μm from the depth of the groove, it is not preferable because the above-described heat uniformity is likely to be adversely affected. The most preferred range is from equivalent to about 10 μm.

  In the present invention, two or more heating elements can be laminated. For example, one surface of a single insulating layer is grooved, a heating element is inserted, and then the non-grooved surface of the insulating layer that is grooved on one side is the insulating layer with the heating element inserted. A resistance heating unit composed of a plurality of layers of heating elements can be formed by inserting heating elements into the grooves of the stacked insulating layers and overlapping the insulating layers that have not been grooved. It is also possible to form a resistance heating unit by performing groove processing on both surfaces of one insulating layer, and it is possible to stack three or more heating elements.

  The mounting table and the support plate of the present invention are preferably made of a material having high thermal conductivity from the viewpoint of heat uniformity. Examples of the material having high thermal conductivity include copper, aluminum, silicon carbide, aluminum nitride, and composite materials containing these. Examples of the composite material include a composite of silicon and silicon carbide (Si—SiC) and a composite of aluminum and silicon carbide (Al—SiC).

  In the combination of the mounting table and the support plate, at least one of them is preferably made of a highly rigid material. The material having high rigidity is a composite containing aluminum nitride, silicon carbide, and ceramics thereof.

  If both the mounting table and the support plate are made of a material with relatively low rigidity, such as aluminum, deformation is likely to occur due to the heat cycle of the resistance heating unit or the like, and the cooling module and the support plate or resistance heating unit Since the adhesiveness with the mounting table changes and the shape of the mounting surface changes, characteristics such as heat uniformity deteriorate, which is not preferable. Further, in order to improve the thermal uniformity of the wafer to be mounted, it is preferable that the thermal conductivity of the mounting table is relatively high and the rigidity (Young's modulus) of the support plate is relatively high.

  The heating element is preferably a metal foil such as stainless steel, nickel chromium alloy, inconel, molybdenum, tungsten. Among these, stainless steel is most preferable because it is general-purpose and inexpensive and circuit forming means such as etching is relatively simple.

  The insulating layer is preferably made of polyimide, mica, Teflon (registered trademark), or the like. Of these, polyimide is most preferred because of its high heat resistance and relatively simple groove forming means such as etching.

  The mounting table and the support plate are preferably mechanically coupled with the resistance heating unit interposed therebetween. When the material of the mounting table and the support hill are different, or when the cooling module is installed on the support plate side, when a normal temperature wafer is mounted on the mounting table, a temperature difference or a thermal expansion difference occurs, which is affected by these effects. This is to make it difficult. Examples of the mechanical coupling method include screwing and fixing by a spring. From the viewpoint of stability, screwing is most preferable as shown in FIG.

  It is preferable to install a support (not shown) for supporting the wafer on the mounting surface. The support forms a minute space between the wafer and the mounting surface to prevent particles from adhering to the backside of the wafer, and improves the temperature distribution (thermal uniformity) of the wafer by forming a minute space. Can be made. The support is preferably installed so that the distance between the wafer and the mounting surface is about 10 to 300 μm.

  The heater unit for heating a wafer according to the present invention preferably includes a movable cooling module below the support plate. For example, the cooling rate can be improved by keeping the cooling module away from the support plate during heating and contacting the support plate during cooling. The cooling module includes a method in which a groove is formed in a plate-like body such as copper or aluminum, a metal pipe is attached to the groove, and water or an organic refrigerant is allowed to flow through the pipe.

  Moreover, a flow path can be formed in one or both of two metal plates, and it can join by brazing or welding to make a cooling module. In addition, the cooling module is not formed with a flow path for flowing the refrigerant, but is brought into contact with a container such as a chamber when the cooling module is separated from the support plate, so that the cooling module is cooled by flowing the refrigerant through the container. It may be a structure.

  Among the above, it is preferable not to form a refrigerant flow path in the cooling module itself because the temperature distribution of the cooling module is less likely to affect the wafer heating heater unit. When the refrigerant flow path is formed in the cooling module, the temperature of the refrigerant introduction portion out is low, but the temperature of the cooling module increases because the temperature of the refrigerant rises near the refrigerant outlet. Occurs. This is because the temperature distribution of the cooling module may affect the temperature distribution of the wafer mounting surface of the wafer heating heater unit.

0.5 part by weight of yttrium oxide (Y ₂ O ₃ ) is added to 99.5 parts by weight of aluminum nitride (AlN) powder, an acrylic binder and an organic solvent are added, and they are mixed for 24 hours in a ball mill to obtain an AlN slurry. Was made. The slurry is spray-dried to produce granules, press-molded, degreased in a nitrogen atmosphere at 700 ° C., and sintered in a nitrogen atmosphere at 1850 ° C. to produce a plurality of aluminum nitride (AlN) sintered bodies. did. This AlN sintered body was machined to have a diameter of 320 mm and a thickness of 3 mm. The surface roughness of the upper and lower surfaces of this AlN sintered body was Ra 0.8 μm, and the flatness was 50 μm. This AlN sintered body was used as a support plate.

  A stainless foil having a thickness of 30 μm was etched into a predetermined circuit pattern to obtain a heating element. A polyimide having a thickness of 50 μm was prepared, and a groove into which a stainless steel foil heating element was inserted was formed by etching so as to have a depth of 25 μm. A stainless steel heating element was inserted into the groove, and a polyimide having a thickness of 50 μm was placed thereon to form a resistance heating unit.

  A copper plate (Cu) having a diameter of 320 mm and a thickness of 3 mm and an aluminum plate (Al) were prepared as mounting tables. The mounting table, the resistance heating unit and the support plate of the AlN sintered body are fixed with screws, a power supply electrode is attached to the stainless steel foil heating element, and a temperature measuring resistance element for temperature control is mounted on the wafer of the mounting table. A heater unit for heating the wafer was installed on the opposite side of the mounting surface.

  As a resistance heating unit, a unit in which stainless steel foil was bonded to a polyimide groove with a heat resistant resin and fixed was also prepared. Also, polyimides that are insulating layers are bonded to each other at 10 locations other than the groove, using a heat-resistant resin in the form of dots having a diameter of about 1 mm at almost equal intervals, and the polyimide is used on the entire surface except for the groove. We prepared a glued one. These resistance heating units, the AlN sintered body, and the mounting table were fixed with screws, and the electrodes and the resistance temperature detectors were similarly attached to produce a heater unit for heating the wafer.

  The thermal uniformity at 230 ° C. of these heater units for heating the wafer was measured. Measurement was performed using a wafer thermometer with a diameter of 300 mm capable of measuring 17 points, and the difference between the maximum temperature and the minimum temperature at 17 points was made uniform.

  Further, after heating to 230 ° C., cooling to 100 ° C., heating again to 230 ° C., holding for 10 minutes, and then cooling to 100 ° C. is performed 1000 times, soaking at 230 ° C. after 1000 times Was also measured.

  In order to increase the cooling speed, a cooling pipe is embedded in the bottom of the chamber, cooling water cooled by a chiller is poured, and an aluminum plate having a thickness of 5 mm and a diameter of 320 mm is used as a movable cooling module. Adhered.

  Further, the flatness of the wafer mounting surface was measured with a three-dimensional measuring instrument before and after the thermal cycle test. These results are shown in Table 1.

  In any of the wafer heating heater units, on the wafer placement surface, one support (proximity) is provided near the center of the wafer placement surface, and eight on the outer periphery of the wafer placement surface. Four pieces were arranged almost evenly in the middle region so that the distance between the wafer mounting surface and the wafer back surface was 0.1 mm.

＊は比較例を示す。

* Indicates a comparative example.

No. of the present invention. In Nos. 1 to 4, there was almost no change in the thermal uniformity and flatness after the thermal cycle. No. 5, heating element and insulating layer No. 6 shows that both the thermal uniformity and the flatness after the heat cycle are deteriorated.
[Comparative Example 1]

  No. 1 in Example 1 except that the method for forming the polyimide groove as the insulating layer was performed by sandblasting and press molding. A wafer heating heater unit similar to 2 was prepared, and the initial thermal uniformity and flatness were measured. Similarly, No. 1 in Example 1 was used. The same heater unit for heating the wafer as in No. 4 was produced, and the initial thermal uniformity and flatness were measured. The results are shown in Table 2.

  No. As a result of the soaking property measured for 7 to 10, a high temperature portion (heat spot) and a low temperature portion (cool spot) were partially present. The depth of the polyimide groove in each part was investigated using a height gauge. As a result, the depth of the groove in the heat spot portion was shallow, and the stainless steel foil as the heating element was strongly pressed, and it was considered that the temperature was high. In addition, the depth of the polyimide groove near the cool spot was deep, and it was estimated that heat was not transferred well from the stainless steel foil as a heating element to the mounting table via the polyimide.

  No. of Example 1 Using the resistance heating unit 2, the material of the mounting table and the material of the support plate are as shown in Table 3, and the thermal uniformity and flatness were measured in the same manner as in Example 1. The results are shown in Table 3.

  As can be seen from Table 3, the combination of the mounting table and the support plate shows that there is almost no change in the flatness and thermal uniformity after the thermal cycle from the initial state when at least one of them is made of a rigid material. . When both the mounting table and the supporting hill are made of metal, the flatness after the heat cycle is deteriorated and the thermal uniformity is slightly deteriorated, but there is no big problem in the processing of the wafer.

  No. of Example 1 1, no. 2 and No. 2 in Example 2. 11 to 19 were mounted on a semiconductor manufacturing apparatus for resist film curing, and 1000 wafers were processed, but the wafer heating units could process the wafers without any change in characteristics. .

  According to the present invention, it is possible to provide a wafer heating heater unit having high reliability and excellent heat uniformity, and a semiconductor manufacturing apparatus equipped with the same.

Reference Signs List 1 mounting table 2 resistance heating unit 3 support plate 4 screw 10 wafer mounting surface 21 heating element 22 insulating layer

Claims (5)

The resistance heating unit, comprising: a mounting table having a wafer mounting surface; a resistance heating unit on a surface opposite to the wafer mounting surface; and a support plate supporting the resistance heating unit. Comprises a heating element and a plurality of insulating layers sandwiching the heating element, and a groove is formed in at least one of the insulating layers, and the heating element is housed in the groove and sandwiched between other insulating layers. cage, wherein the insulating layer each other have a part that is not adhered to each other, the wafer heater unit thickness of the heating element is equal to or greater than the depth of the groove.   The heater unit for heating a wafer according to claim 1, wherein the insulating layers are not bonded to each other.   3. The wafer heating heater unit according to claim 1, wherein the mounting table, the resistance heating unit, and the support plate are mechanically coupled.   4. The wafer heating heater unit according to claim 1, wherein the groove of the insulating layer is formed by an etching process.   5. A semiconductor manufacturing apparatus, wherein the heater unit for heating a wafer according to claim 1 is mounted.

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