Element manufacturing method and heating device

Abstract

The present invention reduces variation in temperature during heating of a wafer. This element manufacturing method includes: a step for causing a gas to flow into a chamber which is capable of housing a wafer; and a step for heating the wafer by conductive heat transfer via the gas, while floating the wafer by using air pressure of the gas in the vertical upward direction.

Description

Element manufacturing method and heating device

[0001] The present disclosure relates to a heating method and a heating apparatus for heating a wafer.

[0002] Patent Document 1 discloses a method for manufacturing a composite piezoelectric substrate.

[0003] Japanese Patent Application Publication No. 2010-273127

[0004] A method for manufacturing an element according to one aspect of the present disclosure includes the steps of: flowing a gas into a chamber capable of accommodating a wafer; and heating the wafer by conductive heat transfer via the gas while floating the wafer by the vertical upward wind pressure of the gas.

[0005] Furthermore, a heating device according to one aspect of the present disclosure has a chamber capable of accommodating a wafer and a flow path for introducing gas into the chamber, and is configured to float the wafer by the vertically upward wind pressure of the gas, while heating the wafer by conductive heat transfer via the gas.

[0006] FIG. 1 is a cross-sectional view showing the configuration of a main part of a heating apparatus according to embodiment 1; FIG. 2 is a plan view of a stage viewed from vertically above; FIG. 3 is a view showing an example of a wafer processing step; FIG. 4 is a view showing an example of a wafer processing step that follows FIG. 3 or FIG. 4; FIG. 5 is a view showing an example of a wafer processing step that follows FIG. 5; FIG. 6 is a view explaining an example of heating by a heating apparatus according to embodiment 1; FIG. 7 is a cross-sectional view showing the configuration of a main part of a heating apparatus according to embodiment 2; FIG. 8 is a plan view of a first surface of a stage in a heating apparatus according to embodiment 2 viewed from vertically above; FIG. 9 is a cross-sectional view showing the configuration of a main part of a heating apparatus according to embodiment 3; FIG. 10 is a plan view of a stage of a heating apparatus according to embodiment 3 viewed from vertically above; FIG. 11 is a cross-sectional view showing the configuration of a main part of a heating apparatus according to embodiment 4;

[0007] [Embodiment 1] Hereinafter, one embodiment of the present disclosure will be described in detail. The relative sizes of components in each drawing do not reflect the relative sizes of components in an actual device or the like.

[0008] (Heating Apparatus 1) Fig. 1 is a cross-sectional view showing the configuration of a main part of a heating apparatus 1 according to embodiment 1. The heating apparatus 1 is an apparatus for heating a wafer 100. As shown in Fig. 1, the heating apparatus 1 may include a chamber 10, a flow path 20, and a stage 30. The heating apparatus 1 may further include wafer transfer claws 40 and an upper cover 50. For simplicity, structures for supporting, for example, the stage 30 are omitted from Fig. 1.

[0009] The chamber 10 is a chamber capable of accommodating a wafer 100. The flow path 20 is a flow path that allows a gas to flow into the chamber 10. Any known chamber 10 and flow path 20 can be used without any particular restrictions. The gas that flows into the chamber 10 via the flow path 20 may be, for example, air, but is not limited to this.

[0010] The stage 30 may be a member on which the wafer 100 to be heated is placed. The stage 30 may have a function of levitating the placed wafer 100. The stage 30 may have a first surface 31a facing the wafer 100. Specifically, the stage 30 may include an upper stage 31 and a lower stage 32. The upper stage 31 may have a first surface 31a and a second surface 31b opposite to the first surface 31a. The lower stage 32 may have a third surface 32a facing the second surface 31b of the upper stage 31.

[0011] The upper stage 31 and the lower stage 32 may be made of aluminum or carbon, for example, and may be made of the same material as or different from each other.

[0012] An airtight member (not shown) may be disposed between the lower stage 32 and the upper stage 31. The airtight member may be, for example, an O-ring. The lower stage 32 may have a communication hole 32b that connects the space formed by the upper stage 31, the lower stage 32, and the airtight member with the outside space. In this case, gas flowing into the chamber 10 via the flow path 20 flows into the space formed by the upper stage 31, the lower stage 32, and the airtight member via the communication hole 32b.

[0013] Furthermore, in this case, the gas may be ejected from the first surface 31a, so that the heating device 1 can float the wafer 100 by the gas ejected from the first surface 31a.

[0014] In the heating apparatus 1, the wafer 100 does not necessarily have to be floating above the first surface 31a at all times, and there may be a moment when the wafer 100 comes into contact with the first surface 31a. For example, the wafer 100 may be floating above the first surface 31a for 95% or more of the time that the wafer 100 is heated by the heating apparatus 1. However, the length of time that the wafer 100 floats above the first surface 31a is not limited to this.

[0015] The heating device 1 may be configured so that the gas is ejected in a dispersed manner from the first surface 31 a. That is, the gas may levitate the wafer 100 by wind pressure at multiple points on the vertically lower surface of the wafer 100. This makes it possible to stabilize the wafer 100 that is levitated by the gas, compared to, for example, a case in which the gas is ejected from a single point on the first surface 31 a.

[0016] Furthermore, the heating apparatus 1 does not necessarily have to include the stage 30. For example, the heating apparatus 1 may have claws for holding the wafer 100 in the air and a plurality of pipes for ejecting gas. In this case, the wafer 100 is heated while being held by the claws.

[0017] FIG. 2 is a plan view of the stage 30 viewed vertically from above. FIG. 2 shows the first and second surfaces 31a and 31b of the upper stage 31, as well as the third surface 32a of the lower stage 32 when viewed through the first surface 31a. As shown in FIG. 2, the upper stage 31 may have a plurality of through-holes 31c formed therein. The through-holes 31c extend from the first surface 31a to the second surface 31b. In this case, gas may be ejected through the through-holes 31c. The manufacturer of the heating device 1 can determine the position and density of the through-holes 31c through which the gas is ejected. For example, the plurality of through-holes 31c may be holes with a diameter of 0.3 mm and spaced at a 5 mm pitch, but this is not a limitation.

[0018] The upper stage 31 or the lower stage 32 may further include a heat generating unit 33 that generates heat. For example, the lower stage 32 is divided into two layers, with the heat generating unit 33 sandwiched between the two layers. The heat generating unit 33 has an opening in the center, and a flow path 20 inside the opening. In this case, the gas ejected from the first surface 31 a is heated by the heat of the heat generating unit 33. The heating device 1 can heat the wafer 100 by conductive heat transfer via the gas while floating the wafer 100 by the vertically upward wind pressure of the gas. The heat generating unit 33 is omitted in the drawings of other embodiments described below.

[0019] However, in the heating apparatus 1, the upper stage 31 or the lower stage 32 does not necessarily have to include the heat generating unit 33. The heating apparatus 1 may also include a heat generating unit outside the upper stage 31 that generates heat for heating the wafer 100.

[0020] The heating device 1 may also be capable of heating the levitated wafer 100 by radiant heat transfer from the upper stage 31. This allows the heat generated by the heat generating portion 33 to be used more efficiently than when the wafer 100 is heated only by conductive heat transfer via gas.

[0021] Furthermore, the stage 30 may have grooves on at least one of the second surface 31 b and the third surface 32 a. In the example shown in Fig. 2, the stage 30 has two grooves 32 c on the third surface 32 a that pass through the center of the third surface 32 a and are perpendicular to each other. By having the grooves 32 c on the stage 30, the grooves 32 c serve as gas flow paths, and the gas is dispersed into each of the through-holes 32 c, facilitating the inflow of the gas.

[0022] 2, when the first surface 31a is viewed from above, the plurality of through holes 31c and the grooves 32c do not need to overlap. If the plurality of through holes 31c and the grooves 32c overlap, gas flowing in from the through holes 31c that overlap with the grooves 32c may stagnate in the grooves 32c, which may deteriorate the uniformity of the amount of gas on the first surface 31a. By preventing the plurality of through holes 31c and the grooves 32c from overlapping, the uniformity of the amount of gas ejected from the first surface 31a can be improved.

[0023] However, the shape of the grooves of the stage 30 is not limited to the example shown in Fig. 2. Furthermore, the stage 30 may have grooves on the second surface 31b instead of the third surface 32a, or may have grooves on both the second surface 31b and the third surface 32a.

[0024] Furthermore, the upper stage 31 does not necessarily have to have multiple through-holes 31c. For example, the upper stage 31 may include a porous material with pores. In this case, the gas is ejected from the first surface 31a through the pores of the porous material. In this case, the gas flow path is fine, so the wafer 100 can be heated uniformly. Furthermore, because the pores are smaller than the through-holes 31c, even if foreign matter is mixed into the gas, the problem of the foreign matter entering the gas flow path and clogging the flow path can be reduced. Furthermore, in the manufacturing process of the heating device 1, the process of forming multiple through-holes 31c in the upper stage 31 is not necessary. Therefore, the manufacturing cost of the heating device 1 may be reduced.

[0025] The wafer transfer claws 40 are used to transfer the wafer 100 between an external wafer transfer device and the heating device 1. The wafer transfer claws 40 may have a placement surface 41 and a restriction surface 42.

[0026] The mounting surface 41 is a substantially horizontal surface on which the wafer 100 is mounted. The substantially horizontal surface here may be any surface that can be regarded as substantially horizontal, and may be inclined within a range of 5° with respect to the horizontal plane, for example.

[0027] The limiting surface 42 is a surface that is approximately perpendicular to the mounting surface 41 and limits the horizontal movement of the wafer 100 placed on the mounting surface 41. Here, the surface that is approximately perpendicular to the mounting surface 41 may be any surface that can be considered to be substantially perpendicular to the mounting surface 41, and may be inclined within a range of 5° with respect to the direction perpendicular to the mounting surface 41, for example. However, the wafer transfer claws 40 may have a portion with a shape different from the limiting surface 42 that limits the horizontal movement of the wafer 100.

[0028] In the heating apparatus 1, the stage 30 may be raised and lowered by a lifting mechanism (not shown). In FIG. 1, the stage 30 is in a lowered position. Furthermore, as shown in FIG. 2, the upper stage 31 may be provided with countersunk holes 31d that accommodate portions of the wafer transfer claws 40. In the example shown in FIG. 2, the upper stage 31 is provided with four countersunk holes 31d. In this case, the heating apparatus 1 may also be provided with four wafer transfer claws 40. However, the number of wafer transfer claws 40 provided in the heating apparatus 1 and the number of countersunk holes 31d provided in the upper stage 31 are not limited to these. Furthermore, the wafer transfer claws 40, rather than the stage 30, may be raised and lowered.

[0029] When the stage 30 is in a lowered state, the first surface 31 a of the stage 30 may be located below the mounting surface 41. When the stage 30 is in a raised state, the first surface 31 a of the stage 30 may be located above the mounting surface 41. In this case, a portion of the wafer transfer claw 40 may be accommodated in the countersunk hole 31 d. The heating device 1 may heat the wafer 100 when the stage 30 is in a raised state so that the first surface 31 a of the stage 30 is higher than the mounting surface 41 of the wafer transfer claw 40.

[0030] However, at least a portion of the limiting surface 42 may be located above the first surface 31 a even when the stage 30 is raised. In this case, the limiting surface 42 limits the movement of the wafer 100 in the horizontal direction even when the wafer 100 is floating above the stage 30. This reduces the possibility that the wafer 100 will fall off the stage 30 while being heated.

[0031] The top lid 50 may be a lid that covers the wafer 100 from above while it is being heated by the heating apparatus 1. Covering the wafer 100 with the top lid 50 reduces contact between the wafer 100 and the unheated, low-temperature outside air, and traps the heat around the wafer 100. This reduces the temperature difference between the top side of the wafer 100, which is closer to the stage 30, and the bottom side, which is farther from the stage 30. The top lid 50 also reduces the possibility that unintended objects, such as dust, will come into contact with the wafer 100 while it is being heated. The top lid 50 may be made of, for example, aluminum or carbon, but is not limited to these.

[0032] (Wafer 100) The wafer 100 may be a laminated substrate made of multiple materials. Such a wafer 100 deforms more when heated than, for example, a wafer made of a single material. In particular, when the linear expansion coefficients of the multiple materials forming the wafer 100 are different from each other, the deformation of the wafer 100 becomes greater. When such a wafer 100 is heated while placed on a pedestal, the deformation causes only a portion of the wafer 100 to come into contact with the pedestal. In this case, the temperature difference between the portion of the wafer 100 that is in contact with the pedestal and the other portions becomes greater. With the heating device 1, even such a wafer 100 can be heated more uniformly than when heated while placed on a pedestal.

[0033] The wafer 100 heated by the heating device 1 may be a bonded wafer including a piezoelectric layer, which is used for an element for a SAW (Surface Acoustic Wave) device. Specifically, the wafer 100 is a LiTaO ３ (LT) or LiNbO ３ The wafer 100 may have a piezoelectric layer containing (LN) and a Si layer.２ The wafer 100 may further include a low acoustic velocity layer containing SiO between the piezoelectric layer and the Si layer. ２ a low acoustic impedance layer comprising HfO ２ The wafer 100 may have four combinations of high acoustic impedance layers including the piezoelectric layer and the Si layer. The wafer 100 may also have a so-called membrane structure in which a space is formed between the piezoelectric layer and the Si layer. The heating device 1 can heat such a wafer 100 more uniformly than when the wafer 100 is heated while placed on a pedestal.

[0034] The wafer 100 may further include an IDT (Interdigital Transducer) electrode on the piezoelectric layer, and may further include a protective film for protecting the IDT electrode.

[0035] In the wafer 100, the piezoelectric layer may be thinner than the Si layer. Specifically, the thickness of the piezoelectric layer may be 30 μm or less. The thickness of the piezoelectric layer may be, for example, 1 μm or less. Alternatively, the thickness of the piezoelectric layer may be determined based on the pitch of the IDT electrodes formed on the piezoelectric layer. Specifically, the thickness of the piezoelectric layer may be two times or less the pitch of the IDT electrodes. On the other hand, the thickness of the Si layer may be 100 μm or more.

[0036] LT or LN has a relatively large linear expansion coefficient. On the other hand, Si has a relatively small linear expansion coefficient. When a wafer 100 made of bonded materials with different linear expansion coefficients is heated, warping of the wafer 100 may occur. The heating apparatus 1 heats such a wafer 100 more uniformly than when it is heated while placed on a pedestal, thereby improving the yield of devices obtained from the wafer 100.

[0037] In the process of heating the wafer 100, the wafer 100 may be arranged such that, of the multiple materials forming the wafer 100, the material with the highest thermal conductivity is positioned vertically downward. This allows heat from the stage 30 to be efficiently transferred to materials arranged farther from the stage 30. Therefore, the entire wafer 100 can be heated more uniformly.

[0038] Furthermore, when the wafer 100 has the above-described piezoelectric layer and Si layer, the thermal conductivity of Si is higher than that of the LT or LN that forms the piezoelectric layer. Therefore, when heating the wafer 100 having a piezoelectric layer and a Si layer, the wafer 100 is positioned so that the Si layer is positioned vertically downward. Here, in the heating apparatus 1, the wafer 100 is not always in a floating state and may collide with the stage 30. Positioning the wafer 100 so that the Si layer is positioned vertically downward reduces the possibility of the pattern surface of the piezoelectric layer, including the IDT electrodes, colliding with the stage 30 and being damaged or broken.

[0039] However, the wafer 100 is not limited to a wafer used for an element for a SAW device, and may be any wafer that requires uniform heating, such as a semiconductor wafer.

[0040] (First Processing Example of Wafer 100) Figure 3 is a diagram showing an example of a process for processing wafer 100. Figure 3 shows an example of a process for forming IDT electrodes by a so-called etching process, which is part of a manufacturing method for manufacturing SAW elements from wafer 100. In this example, a so-called positive photoresist is used as photoresist 140.

[0041] 3, at the start of the process, the wafer 100 has only the Si layer 111 and the piezoelectric layer 112, as indicated by the reference numeral 301. In the following figures, the Si layer 111 and the piezoelectric layer 112 are collectively referred to as the base layer 110. After the surface of the base layer 110 is cleaned, as indicated by the reference numeral 302, a Ti layer 120 and an Al—Cu layer 130, which will be materials for the IDT electrodes, are laminated in this order on the base layer 110. The Ti layer 120 and the Al—Cu layer 130 may be laminated by, for example, a sputtering method. However, the materials and lamination method for the IDT electrodes are not limited to these.

[0042] As indicated by reference numeral 303, photoresist 140 is applied onto the Al—Cu layer 130. Specifically, after the photoresist 140 containing a solvent is applied onto the Al—Cu layer 130, the wafer 100 is baked to remove the solvent. In this state, the photoresist 140 is exposed to light as indicated by reference numeral 304. At this time, the areas of the photoresist 140 to be exposed are limited by a photomask 200. A crosslinking reaction occurs in the exposed photoresist 140, changing its solubility and insolubility in a developer.

[0043] Furthermore, the wafer 100 after exposure is baked again. At this time, the photoresist 140 in the exposed area is heated to cause thermal diffusion, thereby mitigating the effects of standing waves during exposure.

[0044] After baking, the photoresist 140 on the wafer 100 is developed with a developer. As a result, only the photoresist 140 in the exposed areas is removed, as indicated by reference numeral 305. Furthermore, as indicated by reference numeral 306, the Ti layer 120 and the Al—Cu layer 130 are removed by dry etching with a chlorine-based gas from the areas where the photoresist 140 has been removed. The Ti layer 120 and the Al—Cu layer 130 that remain unremoved form the IDT electrodes. Thereafter, as indicated by reference numeral 307, unnecessary photoresist 140 remaining on the Al—Cu layer 130 is removed by ashing using oxygen plasma or the like.

[0045] The heating apparatus 1 may be used in a baking process of the wafer 100, for example, in the process indicated by the reference numeral 303, to remove the solvent from the photoresist 140. This allows the solvent to be uniformly removed from the photoresist 140. The heating apparatus 1 may also be used in a baking process of the wafer 100, for example, in the process indicated by the reference numeral 304, to cause a crosslinking reaction in the exposed photoresist 140. This allows the exposed portions of the photoresist 140 to undergo a uniform crosslinking reaction.

[0046] (Second Processing Example of Wafer 100) Figure 4 is a diagram showing another example of the process of processing wafer 100, different from Figure 3. Figure 4 shows an example of the process of forming IDT electrodes by a so-called lift-off process, which is one of the manufacturing methods for manufacturing SAW elements from wafer 100. In this example, a so-called negative photoresist is used as photoresist 140.

[0047] 4, at the start of the process, the wafer 100 has only the base layer 110, as indicated by reference numeral 401. After the surface of the base layer 110 is cleaned, as indicated by reference numeral 402, a photoresist 140 containing a solvent is applied onto the base layer 110 and baked to remove the solvent.

[0048] After the photoresist 140 is exposed to light, it is baked again, as indicated by the reference numeral 403, causing a crosslinking reaction in the exposed portions of the photoresist 140. The photoresist 140 used here hardens in the exposed portions, unlike the photoresist 140 used in the step of forming the IDT electrodes by the etching process of FIG.

[0049] The photoresist 140 is then developed with a developer, so that only the exposed portions of the photoresist 140 remain on the base layer 110, as shown by reference numeral 404.

[0050] As shown by the reference numeral 405, a Ti layer 120 and an Al—Cu layer 130, which are materials for the IDT electrodes, are laminated in this order on the base layer 110, with the photoresist 140 present on a portion of the surface. The Ti layer 120 and the Al—Cu layer 130 may be laminated by, for example, vapor deposition. However, the materials and lamination method for the IDT electrodes are not limited to these.

[0051] At this time, in the areas where the photoresist 140 exists, the Ti layer 120 and the Al—Cu layer 130 are laminated on top of the photoresist 140. For example, by immersing the wafer 100 in an organic solvent or remover, the photoresist 140 is removed together with the Ti layer 120 and the Al—Cu layer 130 thereon, as shown by reference numeral 406. The Ti layer 120 and the Al—Cu layer 130 that remain unremoved form the IDT electrodes.

[0052] The heating apparatus 1 may be used in a baking process of the wafer 100, for example, in the process indicated by reference numeral 402, to remove the solvent from the photoresist 140. This allows the solvent to be uniformly removed from the photoresist 140. The heating apparatus 1 may also be used in a baking process of the wafer 100, for example, in the process indicated by reference numeral 403, to cause the exposed photoresist 140 to undergo a crosslinking reaction. This allows the exposed portions of the photoresist 140 to undergo a uniform crosslinking reaction.

[0053] In the example of FIG. 4 , as indicated by reference numerals 403 and 404, the wafer 100 is baked a second time, and then the photoresist 140 is immediately developed. However, depending on the type of photoresist 140, the entire surface of the photoresist 140 may be exposed again after the second bake and then developed. For example, when a so-called image reversal resist is used, two exposures are performed. The exposed portions in the first exposure undergo a cross-linking reaction by subsequent baking, changing from positive photoresist to negative photoresist. Meanwhile, the unexposed portions remain as positive photoresist. Then, in the second exposure, the entire surface of the photoresist 140 is exposed and then developed, leaving the portions that have changed to negative photoresist. Then, the Ti layer 120 and the Al—Cu layer 130 are laminated. The photoresist 140 is removed together with the Ti layer 120 and the Al—Cu layer 130 thereon, and the IDT electrodes are formed from the Ti layer 120 and the Al—Cu layer 130 that remain unremoved. Variations in the baking temperature can affect the dimensions of the remaining negative resist, and can also affect the line width of the IDT electrodes, etc.

[0054] (Third Processing Example of Wafer 100) Fig. 5 is a diagram showing an example of a process subsequent to Fig. 3 or Fig. 4 in the process of processing wafer 100. Fig. 5 shows an example of a manufacturing method for manufacturing SAW elements from wafer 100, in which wiring electrodes are further formed on wafer 100 in a state in which IDT electrodes have been formed by the series of processes shown in Fig. 3 or Fig. 4.

[0055] 5, as shown in FIG. 5, a protective film 150 is formed on the surface of the wafer 100 on which the IDT electrodes have been formed, as indicated by the reference numeral 501. The protective film 150 is made of, for example, SiO ２ Next, as indicated by reference numeral 502, photoresist 140 is applied to regions other than the regions where the wiring electrodes are to be formed. At this time, as described with reference to reference numerals 302 to 304 in FIG. 3 , application of photoresist 140, baking, exposure, baking again, and development may be performed. At this time, one or both of the two baking steps may be performed by the heating device 1.

[0056] As shown by reference numeral 503, the protective film 150 is removed from the area where the photoresist 140 is not present, and then an Al / Ti layer 160, which will be the material for the wiring electrodes, is laminated as shown by reference numeral 504. The Al / Ti layer 160 may be laminated by vapor deposition, for example. However, the material and lamination method for the wiring electrodes are not limited to these.

[0057] Thereafter, as shown by the reference numeral 505, the photoresist 140 is removed together with the Al / Ti layer 160. As a result, the Al / Ti layer 160 remaining only in the area where the photoresist 140 was not present forms a wiring electrode.

[0058] Fig. 6 is a diagram showing an example of a process subsequent to Fig. 5 in the process of processing the wafer 100. Fig. 6 shows an example of a manufacturing method for manufacturing SAW elements from the wafer 100, in which pad electrodes 170 are further formed on the wafer 100 in a state in which wiring electrodes have been formed by the processing of Fig. 5.

[0059] 6, as indicated by reference numeral 601, photoresist 140 is applied to the wafer 100 on which wiring electrodes have been formed, in areas other than the areas on which pad electrodes are to be formed. At this time, as described with reference to reference numerals 302 to 304 in FIG. 3, application of photoresist 140, baking, exposure, baking again, and development may be performed. At this time, one or both of the two baking steps may be performed by the heating apparatus 1.

[0060] As shown by reference numeral 602, the protective film 150 is removed from the areas where the photoresist 140 is not present. Then, as shown by reference numeral 603, an Au / Ni / Cr layer 170, which will be the material for the pad electrode, is deposited. The Au / Ni / Cr layer 170 may be deposited by, for example, vapor deposition. However, the material and deposition method for the pad electrode are not limited to this. The photoresist 140 is then removed together with the Au / Ni / Cr layer 170 thereon. As shown by reference numeral 604, the Au / Ni / Cr layer 170 remaining only in the areas where the photoresist 140 was not present forms the pad electrode. Then, as shown by reference numeral 605, a solder ball 180 for connecting the SAW element to another element is mounted on the Au / Ni / Cr layer 170 on which the pad electrode has been formed.

[0061] The wafer 100 illustrated up to this point has not been the entire wafer 100, but rather a single SAW element region included in the wafer 100. As shown by the reference numeral 606, the processing of the wafer 100, i.e., the process of manufacturing a plurality of SAW elements from the wafer 100, is completed by a dicing process in which each SAW element region is separated from the other regions.

[0062] However, the element manufacturing method according to this embodiment is not limited to the examples described above with reference to Figures 3 to 6. The element manufacturing method according to this embodiment only needs to include a step of heating the wafer 100 by a heating method using the heating apparatus 1. Furthermore, the element manufacturing method according to this embodiment is not limited to a method of manufacturing a SAW element, and may be, for example, a method of manufacturing a semiconductor element.

[0063] (Example) FIG. 7 is a diagram illustrating an example of a heating method using the heating apparatus 1. In addition to the example, FIG. 7 also shows a comparative example. In both the example and the comparative example, the wafer 100 was a bonded wafer having an LT layer and a Si layer. The thickness of the LT layer was 20.1 μm, and the thickness of the Si layer was 500 μm. The heating temperature was 105° C., and the heating time was 10 minutes. Heating was performed only from below the wafer 100. As described above, in the example, the wafer 100 was heated while floating. The gas supplied from the flow path 20 into the chamber 10 was air at 0.3 MPa. In the comparative example, heating was performed using a heating apparatus that heated the wafer 100 without floating it.

[0064] 7, reference numeral 701 indicates the temperature distribution of the wafer 100 in the comparative example, and reference numeral 702 indicates the temperature distribution of the wafer 100 in the example. In reference numerals 701 and 702, the darker the color, the higher the temperature, and the lighter the color, the lower the temperature.

[0065] The center of the wafer 100 in the vertical direction on the paper surface of FIG. 7 was deformed into a shape that was convex upward from the stage. Therefore, in the comparative example, only the upper and lower ends of the wafer 100 were in contact with the stage. As a result, a large variation in temperature distribution was observed between the upper and lower ends of the wafer 100 and the rest of the wafer. Specifically, the difference between the maximum and minimum values ​​of the temperature distribution of the wafer 100 in the comparative example was 5.4°C.

[0066] On the other hand, in the example, the wafer 100 was heated in a floating state, and therefore no significant variation in temperature distribution was observed compared to the wafer 100 in the comparative example. Specifically, the difference between the maximum and minimum values ​​in the temperature distribution of the wafer 100 in the example was 1.1°C.

[0067] In FIG. 7 , reference numeral 703 indicates the distribution of the duty ratio of the wafer 100 in the comparative example, and reference numeral 704 indicates the distribution of the duty ratio of the wafer 100 in the example. The duty ratios indicated by reference numerals 703 and 704 are the ratios of the width of the IDT electrodes formed on the wafer 100 by the process shown in FIG. 3 or 4 to the pitch of the IDT electrodes. Reference numeral 703 indicates the case where both of the two bakes in the process shown in FIG. 3 or 4 were heated using the heating method of the comparative example. Reference numeral 704 indicates the case where both of the bakes in the process shown in FIG. 4 were heated using the heating method of the example. In reference numerals 703 and 704, the darker the color, the smaller the duty ratio, and the lighter the color, the larger the duty ratio.

[0068] In Figure 7, reference numeral 705 indicates the distribution of center frequencies within a band of the wafer 100 in the comparative example, and reference numeral 706 indicates the distribution of center frequencies within a band of the wafer 100 in the example. The center frequencies within a band indicated by reference numerals 705 and 706 refer to the distribution of center frequencies within a band to be transmitted in elements for SAW devices obtained from each position on the wafer 100 by the processes shown in Figures 3 to 6. Reference numeral 705 indicates the case where all baking in the process was performed using the heating method of the comparative example. Reference numeral 706 indicates the case where all baking in the process was performed using the heating method of the example. In reference numerals 705 and 706, the darker the color, the larger the distribution of center frequencies, and the lighter the color, the smaller the distribution of center frequencies.

[0069] As described above, the wafer 100 in the comparative example exhibited large variations in temperature distribution. Therefore, large variations were also observed in the duty ratio distribution and the frequency bandwidth distribution. Specifically, the difference between the maximum and minimum values ​​of the frequency duty ratio for the wafer 100 in the comparative example was 0.046. Furthermore, the variance Fσ of the center frequency distribution was 1.4 MHz.

[0070] On the other hand, as described above, no significant variation in temperature distribution was observed in the wafer 100 of the example. Therefore, no significant variation was observed in the duty ratio distribution or the frequency bandwidth distribution. Specifically, the difference between the maximum and minimum values ​​of the frequency duty ratio in the wafer 100 of the comparative example was 0.031. Furthermore, the variance Fσ of the center frequency distribution was 0.8 MHz.

[0071] As described above, it was confirmed that the wafer 100 of the example had smaller variations in temperature distribution than the wafer 100 of the comparative example. It was also confirmed that the wafer 100 of the example had smaller variations in duty ratio and dispersion of the center frequency distribution than the wafer 100 of the comparative example.

[0072] (Effects) As described above, the heating apparatus 1 includes the chamber 10, the flow path 20, the stage 30, and the heat generating unit 33. The heating apparatus 1 having this configuration is configured to levitate the wafer 100 by vertically upward gas pressure and heat the wafer 100 by conductive heat transfer via the gas. In other words, the heating method using the heating apparatus 1 includes the steps of: introducing gas into the chamber 10; and heating the wafer 100 by vertically upward gas pressure and heating the wafer 100 by conductive heat transfer via the gas. Therefore, the wafer 100 can be heated more uniformly than when the wafer 100 is heated while placed on a pedestal. Therefore, for example, when dicing multiple elements formed on the wafer 100 to manufacture individual elements, variations in element characteristics due to variations in temperature during heating of the wafer 100 are reduced.

[0073] Furthermore, with the above configuration, temperature variations among different portions of the wafer 100 are reduced, thereby improving the yield of devices manufactured from the wafer 100. This reduces the waste of resources caused by the disposal of defective products. This effect also contributes to the achievement of Goal 12 of the Sustainable Development Goals (SDGs) advocated by the United Nations, "Responsible Consumption and Production." This effect is also common to other embodiments described below.

[0074] [Embodiment 2] Another embodiment of the present disclosure will be described below. For convenience of explanation, the same reference numerals will be used to designate components having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0075] Fig. 8 is a cross-sectional view showing the configuration of the main parts of a heating device 2 according to embodiment 2. As shown in Fig. 8, the heating device 2 may differ from the heating device 1 in that it includes a stage 60 instead of the stage 30, and in that it further includes an adjustment mechanism 21, a measurement unit 70, and a pressure control unit 75. Furthermore, the heating device 2 may include a plurality of flow channels 20, as described below.

[0076] The stage 60 may be a member on which the wafer 100 to be heated is placed. The stage 60 may have a function of levitating the placed wafer 100. The stage 60 may have a first surface 61a facing the wafer 100. Specifically, the stage 60 may include an upper stage 61 and a lower stage 62. In this case, the upper stage 61 may have the first surface 61a. An airtight member (not shown) may be disposed between the lower stage 62 and the upper stage 61. Furthermore, the lower stage 62 may have a communication hole (not shown) that connects the space formed by the upper stage 61, the lower stage 62, and the airtight member with an external space.

[0077] Fig. 9 is a plan view of the first surface 61a of the stage 60 in the heating device 2 as viewed vertically from above. In Fig. 9, reference numerals 901 and 902 indicate different examples of the first surface 61a.

[0078] In the example indicated by the reference numeral 901, the first surface 61a is divided into four regions R11, R12, R13, and R14. The regions R11 to R14 may be fan-shaped regions obtained by dividing the circular first surface 61a by two straight lines that pass through the center of the first surface 61a and are perpendicular to each other. When the first surface 61a is divided into four regions R11 to R14, the heating device 2 may include a separate flow path 20 for introducing gas into the chamber 10, corresponding to each of the regions R11 to R14. In this case, the lower stage 62 may have a communication hole corresponding to each of the regions R11 to R14.

[0079] In the example indicated by the reference numeral 902, the first surface 61a is divided into five regions R21, R22, R23, R24, and R25. Region R25 may be a region concentric with, but smaller than, the outer periphery of the first surface 31a. Regions R21 to R24 may be regions obtained by dividing the area between the outer periphery of the first surface 31a and region R25 by two straight lines that pass through the center of the first surface 61a and are perpendicular to each other. When the first surface 61a is divided into five regions R21 to R25, the heating device 2 may include separate flow paths 20 for introducing gas into the chamber 10, each corresponding to one of the regions R21 to R25. In this case, the lower stage 62 may have a communication hole corresponding to each of the regions R21 to R25.

[0080] In particular, in the example shown by reference numeral 902, the wafer 100 may be floated mainly by gas from region R25, and then the degree of floating near the outer periphery of the wafer 100 may be finely adjusted by gas from regions R21 to R24. In this case, the number of through holes 31c present in region R25 may be greater than the number of through holes 31c present in each of regions R21 to R24. For example, if the number of through holes 31c per unit area is constant in regions R21 to R25, the area of ​​region R25 may be greater than the areas of regions R21 to R24.

[0081] The number and shape of the divided regions on the first surface 61a are not limited to those shown in Fig. 9. The heating device 2 may have separate flow paths 20 corresponding to the divided regions on the first surface 61a. Furthermore, the regions do not need to be strictly separated by, for example, physical barriers. In this case, gases flowing in from different flow paths 20 are mixed near the boundaries between the regions.

[0082] The adjustment mechanism 21 may have a function of adjusting the gas supply pressure depending on the portion of the wafer 100. Specifically, the adjustment mechanism 21 may have a function of adjusting the pressure of the gas from the flow path 20 in each of the above-mentioned regions. In the example shown in Figure 8, the adjustment mechanism 21 is a valve that is provided in the middle of the flow path 20 corresponding to each of the above-mentioned regions and can change the cross-sectional area of ​​the flow path 20. In this case, the gas supply pressure is adjusted by changing the opening of the valve.

[0083] The measuring unit 70 may have a function of measuring the warpage shape or temperature of the wafer 100. The measuring unit 70 may be, for example, a distance sensor provided at the center of the top lid 50 in a plan view from the vertical direction, which measures the distance to each part of the wafer 100 using a laser. The measuring unit 70 may also be, for example, an infrared sensor provided at the center of the top lid 50, which measures the temperature of each part of the wafer 100. However, the configuration of the measuring unit 70 is not limited to these as long as it is capable of measuring the warpage shape or temperature of the wafer 100. The measuring unit 70 outputs a signal indicating the measurement value of the warpage shape or temperature of the wafer 100 to the pressure control unit 75.

[0084] The pressure control unit 75 may adjust the pressure of the gas supplied between the upper stage 61 and the lower stage 62 from the flow paths 20 corresponding to each region of the first surface 61 a using the adjustment mechanism 21, in accordance with the measurement value of the measurement unit 70. In the example shown in Fig. 8, the pressure control unit 75 adjusts the gas supply pressure by changing the opening degree of the adjustment mechanism 21, which is a valve. In particular, the pressure control unit 75 may adjust the pressure of the gas supplied between the upper stage 61 and the lower stage 62 from the flow paths 20 corresponding to each region so as to reduce variations in the warpage shape or temperature of the wafer 100.

[0085] However, the heating apparatus 2 does not necessarily have to include the pressure control unit 75. For example, an operator of the heating apparatus 2 may manually adjust the pressure of the gas supplied between the upper stage 61 and the lower stage 62 from the flow paths 20 corresponding to the respective regions, using the adjustment mechanism 21, based on the warpage shape or temperature of the wafer 100 obtained by the measurement unit 70.

[0086] In the heating method using the heating device 2, the warpage shape or temperature of the wafer 100 is measured, and the pressure of the gas supplied between the upper stage 61 and the lower stage 62 is adjusted according to the warpage shape or temperature. For example, the gas supply pressure may be higher for portions of the wafer 100 that are separated from the upper stage 61 due to warpage or for portions with lower temperatures than for other portions. This increases the degree of heating due to conductive heat transfer via the gas, thereby increasing the temperature. Therefore, the heating method using the heating device 2 allows the wafer 100 to be heated more uniformly.

[0087] Third Embodiment Still another embodiment of the present disclosure will be described below.

[0088] Fig. 10 is a cross-sectional view showing the configuration of the main parts of a heating device 3 according to embodiment 3. As shown in Fig. 10, the heating device 3 may differ from the heating device 1 in that it includes a stage 80 instead of the stage 30, and in that it further includes a measuring unit 70 and a pressure control unit 75.

[0089] The stage 80 may be a member on which the wafer 100 to be heated is placed. The stage 80 may have a function of levitating the placed wafer 100. The stage 80 may have a first surface 81a facing the wafer 100. Specifically, the stage 80 may include an upper stage 81 and a lower stage 82. In this case, the upper stage 81 may have the first surface 81a. An airtight member (not shown) may be disposed between the lower stage 82 and the upper stage 81. Furthermore, the lower stage 82 may have a communication hole (not shown) that connects the space formed by the upper stage 81, the lower stage 82, and the airtight member with an external space.

[0090] 11 is a plan view of the stage 80 as viewed vertically from above. The stage 80 is provided with an adjustment flow path (not shown) that allows gas supplied between the upper stage 81 and the lower stage 82 to escape laterally. Furthermore, the stage 80 may be provided with a plurality of adjustment mechanisms 83 on its side. For ease of visibility, the adjustment mechanisms 83 are shown vertically above the stage 80 in FIG. 11.

[0091] The adjustment mechanism 83 is a valve that adjusts the flow rate of gas flowing through the adjustment channel. The adjustment mechanism 83 may be, for example, a needle valve. When the opening degree of the adjustment mechanism 83 is large, the flow rate of gas flowing toward the side of the stage 80 through the adjustment channel is higher than when the opening degree of the adjustment mechanism 83 is small. Therefore, the pressure of the gas supplied between the upper stage 81 and the lower stage 82 through the channel 20 in the vicinity of the adjustment mechanism 83 decreases. In FIG. 11 , the stage 80 includes six adjustment mechanisms 83. The six adjustment mechanisms 83 are arranged at equal angular intervals from one another in the circumferential direction of the stage 80. However, the number and arrangement of the adjustment mechanisms 83 included in the stage 80 are not limited to this.

[0092] In the heating apparatus 3, the pressure control unit 75 controls the pressure of the gas supplied between the upper stage 81 and the lower stage 82 via the flow path 20 by adjusting the opening degree of each adjustment mechanism 83. However, the heating apparatus 3 does not necessarily have to include the pressure control unit 75. For example, an operator of the heating apparatus 3 may manually adjust the pressure of the gas supplied between the upper stage 81 and the lower stage 82 via the flow path 20 using the adjustment mechanism 83 based on the warpage shape or temperature of the wafer 100 obtained by the measurement unit 70.

[0093] In the heating method using heating device 3, the warpage shape or temperature of wafer 100 is measured, and the pressure of the gas supplied between upper stage 81 and lower stage 82 is adjusted according to the warpage shape or temperature using a method different from that used in the heating method using heating device 2. The heating method using heating device 3 also makes it possible to heat wafer 100 more uniformly.

[0094] Fourth Embodiment Still another embodiment of the present disclosure will be described below.

[0095] Fig. 12 is a cross-sectional view showing the configuration of the main parts of a heating device 4 according to embodiment 4. As shown in Fig. 12, the heating device 4 further includes an upper gas injection unit 90 in addition to the configuration of the heating device 1. For simplicity, a structure supporting the upper gas injection unit 90 is omitted in Fig. 12.

[0096] The upper gas injection unit 90 injects heated gas from above the wafer 100. That is, in the heating method using the heating device 4, heated gas is injected from above the wafer 100. The heating device 4 may further include a flow path (not shown) for supplying gas to the upper gas injection unit 90. The upper gas injection unit 90 may further include a heat generating unit (not shown) for heating the gas. The upper gas injection unit 90 may be integrated with the upper lid 50, or the upper lid 50 may have a through-hole, a flow path, a heat generating unit, etc.

[0097] In the heating method using the heating device 4, the wafer 100 may be heated by conductive heat transfer via gas from the first surface 31a of the stage 30, as well as by conductive heat transfer via gas from the upper gas injection unit 90. Furthermore, the wafer 100 may be heated by radiant heat transfer from the stage 30, as well as by radiant heat transfer from a heat generating unit provided in the upper gas injection unit 90. In the heating method using the heating device 4, the wafer 100 is heated from above and below, thereby allowing the wafer 100 to be heated more uniformly.

[0098] The invention according to the present disclosure has been described above based on the drawings and examples. However, the invention according to the present disclosure is not limited to the above-described embodiments. In other words, the invention according to the present disclosure can be modified in various ways within the scope of the present disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the invention according to the present disclosure. In other words, it should be noted that a person skilled in the art can easily make various modifications or corrections based on the present disclosure. It should also be noted that these modifications or corrections are included in the scope of the present disclosure.

[0099] [Summary] The present disclosure can also be expressed as follows.

[0100] A method for manufacturing an element according to aspect 1 of the present disclosure includes the steps of: flowing a gas into a chamber capable of accommodating a wafer; and heating the wafer by conductive heat transfer via the gas while floating the wafer by the vertical upward wind pressure of the gas.

[0101] Aspect 2 of the present disclosure relates to the method of manufacturing an element in aspect 1, wherein the gas floats the wafer by applying wind pressure to a plurality of points on the vertically lower surface of the wafer.

[0102] A third aspect of the present disclosure relates to a method for manufacturing an element in accordance with the first or second aspect, wherein the gas is injected through a through-hole in a stage facing the wafer.

[0103] In the element manufacturing method according to aspect 4 of the present disclosure, in addition to aspect 1 or 2, the gas is injected through pores in a stage that faces the wafer and includes a porous material.

[0104] A fifth aspect of the present disclosure relates to a method for manufacturing an element in the third or fourth aspect, wherein the wafer is heated by radiative heat transfer from the stage.

[0105] A sixth aspect of the present disclosure relates to a method for manufacturing an element in any one of the first to fifth aspects, wherein the supply pressure of the gas is adjusted depending on the portion of the wafer.

[0106] A seventh aspect of the present disclosure relates to a method for manufacturing an element according to the sixth aspect, wherein the warpage shape or temperature of the wafer is measured, and the supply pressure of the gas is adjusted according to the warpage shape or the temperature.

[0107] According to an eighth aspect of the present disclosure, in the method for manufacturing an element in any one of the first to seventh aspects, heated gas is injected from above the wafer.

[0108] A ninth aspect of the present disclosure relates to a method for manufacturing an element in any one of the first to eighth aspects, wherein the wafer is a bonded substrate made of a plurality of materials.

[0109] A tenth aspect of the present disclosure provides a method for manufacturing an element according to the ninth aspect, wherein the wafer is made of LiTaO ３or LiNbO ３ and a Si layer.

[0110] An eleventh aspect of the present disclosure provides a method for manufacturing an element according to the tenth aspect, wherein the piezoelectric layer is thinner than the Si layer.

[0111] A twelfth aspect of the present disclosure relates to a method for manufacturing an element in any one of aspects 9 to 11, wherein the wafer is arranged so that the material with the highest thermal conductivity among the plurality of materials is located vertically downward.

[0112] A heating device according to aspect 13 of the present disclosure has a chamber capable of accommodating a wafer and a flow path for introducing gas into the chamber, and is configured to float the wafer by the vertically upward wind pressure of the gas, while heating the wafer by conductive heat transfer via the gas.

[0113] A heating apparatus according to a fourteenth aspect of the present disclosure is the heating apparatus of the thirteenth aspect, further comprising a stage having a first surface facing the wafer, and configured so that the gas is ejected from the first surface.

[0114] A heating device according to Aspect 15 of the present disclosure is the heating device of Aspect 14, wherein the gas is configured to be dispersed and ejected from the first surface.

[0115] A heating device according to Aspect 16 of the present disclosure is the heating device of Aspect 14 or 15, wherein the gas is configured to be ejected through a through-hole in the stage.

[0116] A heating device according to aspect 17 of the present disclosure is, in aspect 16, wherein the stage has an upper stage having the through holes and a lower stage having a third surface facing a second surface opposite the first surface of the upper stage, and at least one of the second surface and the third surface has a groove, and when viewed from a plane perspective of the first surface, the multiple through holes and the groove do not overlap.

[0117] A heating device according to aspect 18 of the present disclosure is the same as aspect 14, wherein the stage is formed of a porous material and the gas is configured to be ejected from the first surface through pores in the porous material.

[0118] A heating device according to aspect 19 of the present disclosure is any one of aspects 14 to 18, wherein the stage further has a heat generating portion that generates heat, and is configured to be able to heat the levitated wafer by radiative heat transfer from the first surface.

[0119] The heating device according to Aspect 20 of the present disclosure is in any one of Aspects 14 to 19, further comprising an adjustment mechanism for adjusting the gas supply pressure depending on the portion of the wafer.

[0120] The heating apparatus according to aspect 21 of the present disclosure is the same as in aspect 20, further comprising a measurement unit that measures the warpage shape or temperature of the wafer, and a pressure control unit that changes the supply pressure of the gas using the adjustment mechanism in accordance with the measurement value of the measurement unit.

[0121] A heating device according to Aspect 22 of the present disclosure is in any one of Aspects 13 to 21, wherein heated gas is injected from above the wafer.

[0122] A heating apparatus according to a twenty-third aspect of the present disclosure is any one of the thirteenth to twenty-second aspects, wherein the wafer is a bonded substrate made of multiple materials.

[0123] A heating apparatus according to Aspect 24 of the present disclosure is the heating apparatus of Aspect 23, wherein the wafer is LiTaO ３ or LiNbO ３ and a Si layer.

[0124] A heating apparatus according to aspect 25 of the present disclosure is the same as aspect 23 or 24, wherein the wafer is arranged such that the material with the highest thermal conductivity among the plurality of materials is positioned vertically below.

[0125] 1, 2, 3, 4 Heating device 10 Chamber 20 Flow path 21, 83 Adjustment mechanism 30, 60, 80 Stage 31, 61, 81 Upper stage 31a, 61a, 81a First surface 31b Second surface 31c Through hole 32, 62, 82 Lower stage 32a Third surface 32c Groove 70 Measurement unit

Claims

1. flowing a gas into a chamber capable of containing a wafer; and heating the wafer by conductive heat transfer via the gas while floating the wafer by vertically upward wind pressure of the gas. Element manufacturing method.

2. the gas floats the wafer by applying wind pressure to a plurality of points on the vertically lower surface of the wafer; A method for manufacturing the element according to claim 1 .

3. The gas is injected through a through-hole in a stage facing the wafer. A method for manufacturing the element according to claim 1 .

4. The gas is injected through pores in a stage including a porous material facing the wafer. A method for manufacturing the element according to claim 1 .

5. heating the wafer by radiative heat transfer from the stage; A method for manufacturing the element according to claim 3 or 4.

6. adjusting the supply pressure of the gas according to the portion of the wafer; A method for manufacturing the element according to any one of claims 1 to 4.

7. measuring the warpage shape or temperature of the wafer; adjusting the supply pressure of the gas in accordance with the warpage shape or the temperature; The method for manufacturing the element according to claim 6 .

8. Injecting heated gas from above the wafer; A method for manufacturing the element according to any one of claims 1 to 4.

9. The wafer is a bonded substrate made of multiple materials. A method for manufacturing the element according to any one of claims 1 to 4.

10. The wafer is LiTaO ３ or LiNbO ３ and a Si layer, The method for manufacturing the element according to claim 9 .

11. The piezoelectric layer is thinner than the Si layer. The method for manufacturing the element according to claim 10.

12. The wafer is arranged such that a material having a high thermal conductivity among the plurality of materials is positioned vertically downward. The method for manufacturing the element according to claim 9 .

13. a chamber capable of accommodating a wafer; a flow path for allowing a gas to flow into the chamber; The wafer is levitated by the vertically upward wind pressure of the gas, and the wafer is heated by conductive heat transfer via the gas. heating device.

14. a stage having a first surface facing the wafer; The gas is configured to be ejected from the first surface. The heating device according to claim 13.

15. The gas is configured to be dispersed and ejected from the first surface.

15. The heating device of claim 14.

16. The gas is configured to be ejected through a through-hole in the stage.

15. The heating device of claim 14.

17. The stage is an upper stage having the through hole; a lower stage having a third surface facing a second surface of the upper stage opposite to the first surface, a groove in at least one of the second surface and the third surface; When the first surface is seen through in a plan view, the plurality of through holes and the groove do not overlap with each other.

17. The heating device of claim 16.

18. the stage is formed of a porous material; The gas is configured to be ejected from the first surface through pores of the porous material.

15. The heating device of claim 14.

19. the stage further includes a heat generating portion that generates heat, The floating wafer can be heated by radiative heat transfer from the first surface.

19. A heating device according to any one of claims 14 to 18.

20. 19. The heating device according to claim 14, further comprising an adjusting mechanism for adjusting the supply pressure of the gas depending on the portion of the wafer.

21. a measurement unit that measures the warpage shape or temperature of the wafer; and a pressure control unit that changes the supply pressure of the gas by the adjustment mechanism in accordance with the measurement value of the measurement unit.

21. The heating device of claim 20.

22. Injecting heated gas from above the wafer; 19. A heating device according to any one of claims 13 to 18.

23. The wafer is a bonded substrate made of multiple materials.

19. A heating device according to any one of claims 13 to 18.

24. The wafer is LiTaO ３ or LiNbO ３ and a Si layer, 24. The heating device of claim 23.

25. The wafer is arranged such that a material having a high thermal conductivity among the plurality of materials is positioned vertically downward.

24. The heating device of claim 23.