Ceramic heater

Abstract

The application discloses a ceramic heater and belongs to the technical field of semiconductor device manufacturing. The ceramic heater comprises a ceramic plate with a wafer loading surface, a main heating body arranged in the ceramic plate, and an auxiliary heating body arranged on the side surface of the ceramic plate and independent of the main heating body. The auxiliary heating body arranged on the side surface of the ceramic plate and independent of the main heating body can effectively reduce the heat deviation between the middle region and the edge region of the wafer loading surface of the ceramic plate, greatly improving the overall heating uniformity of the wafer. When the wafer on the wafer loading and heating surface is heated, if the heat dissipation of the edge region of the ceramic plate is large, the heat received by the wafer in the edge region is obviously smaller than that in the middle region. The auxiliary heating body generates heat in operation, effectively inhibits the heat dissipation of the edge region of the ceramic plate, and thus the overall heating of the wafer is uniform.

Description

Technical Field

[0001] This application relates to the field of semiconductor equipment manufacturing technology, and specifically to a ceramic heater. Background Technology

[0002] The semiconductor chip manufacturing process generally involves creating the required conductive, dielectric, and insulating pattern structures on a wafer through processes such as photolithography, etching, sputtering, and evaporation. The wafer is then diced into individual chips and packaged into finished products. During wafer processing, ceramic heaters are typically used to support and heat the wafer. A ceramic heater usually consists of a ceramic plate, a heating element built into the ceramic plate, a support shaft, and power supply lines that supply power to the heating element. The wafer is placed on the support surface of the ceramic plate, and the heating element generates heat when energized. The heat is transferred to the wafer through the ceramic plate, thus heating the wafer.

[0003] As chip manufacturing precision increases, stricter requirements are placed on the uniformity of wafer heating during the processing. In current ceramic heaters, the heat generated by the heating element is mainly transferred towards the bearing surface and the opposite side of the bearing surface in the middle region of the ceramic plate. However, in the edge region of the ceramic plate, in addition to the aforementioned two directions, heat is also transferred towards the side of the ceramic plate. This results in a significant difference in the amount of heat received by the edge and middle regions of the wafer, causing uneven heating of the wafer as a whole, which adversely affects chip quality.

[0004] CN114585114A discloses a ceramic heater that uses a first resistive heating element and a second resistive heating element arranged parallel to the wafer mounting surface, with the wiring of the second resistive heating element positioned approximately centered between the wiring of the first resistive heating element. This makes it easier to obtain the target temperature distribution compared to arranging the wiring of the first and second resistive heating elements in an overlapping manner when viewed from above; however, it cannot effectively reduce the heat deviation between the central and edge regions of the ceramic plate mounting surface.

[0005] Therefore, how to reduce the heat deviation between the middle and edge areas on the ceramic plate bearing surface has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] The purpose of this application is to overcome the shortcomings of the existing technology and provide a ceramic heater. By setting an auxiliary heating element independent of the main heating element on the side of the ceramic plate in the ceramic heater, the heat deviation between the middle area and the edge area on the ceramic plate bearing surface can be effectively reduced, and the overall heating uniformity of the wafer can be greatly improved.

[0007] To achieve the above objectives, the technical solution adopted in this application is as follows: A ceramic heater, comprising: Ceramic plate with wafer mounting surface; The main heating element is disposed inside the ceramic plate; An auxiliary heating element is disposed on the side of the ceramic plate and is independent of the main heating element.

[0008] This application innovatively sets an auxiliary heating element, independent of the main heating element, on the side of the ceramic plate. This can effectively reduce the heat deviation between the middle and edge areas of the ceramic plate bearing surface, greatly improving the overall heating uniformity of the wafer. When the wafer on the bearing heating surface is heated, if the edge area of ​​the ceramic plate dissipates heat more, resulting in the wafer receiving significantly less heat in the edge area than in the middle area, the auxiliary heating element generates heat, effectively suppressing heat dissipation in the edge area of ​​the ceramic plate, thereby ensuring uniform heating of the wafer as a whole.

[0009] In the ceramic heater of this application, the main heating element includes multiple arc segments with different radii and multiple transition segments. The arc segments and the transition segments are alternately arranged and connected end to end in sequence, and the connection between the transition segment and the arc segment forms a rounded corner.

[0010] In the prior art, the connection between the arc segment and the transition segment is usually set at a right angle, such as CN108028220A and CN114585114 A. After extensive research, the inventors found that when the connection between the arc segment and the transition segment is set at a right angle, the connection point is prone to stress concentration due to the repeated rapid heating and cooling process of the ceramic heater, which can cause the heating element to crack.

[0011] This application alternates between the arc segments and the transition segments and connects them end to end in sequence. In this way, the arc segments are connected in series, and the transition segments and the arc segments form rounded corners. This can effectively prevent stress concentration at the connection points due to repeated temperature rises and falls, and thus effectively prevent the heat-generating element from collapsing.

[0012] In the ceramic heater of this application, the two arc segments with the smallest radius in the main heating element respectively form a first port and a second port, so that current flows in from the first port and flows out from the second port.

[0013] In the ceramic heater of this application, the radius of the arc segment with the largest radius in the main heating element is R. In the area covered by 2R / 3, the distance between adjacent arc segments is S1. In the area covered by 2R / 3~R, the distance between adjacent arc segments is S2, where S1>S2.

[0014] In the main heating elements arranged in concentric circles, the distance S1 between two adjacent arc segments in the main heating element is large in the middle region near the ceramic plate (within the area covered by 2R / 3), and the heat generation density in this region is relatively low. In the edge region near the ceramic plate (within the area covered by 2R / 3~R), the distance S2 between two adjacent arc segments in the main heating element is small, and the heat generation density in this region is relatively high. This further reduces the heat difference between the middle region and the edge region of the ceramic plate, making the overall heating of the wafer more uniform.

[0015] In the ceramic heater of this application, the ratio of S1 to S2 satisfies: 1.2 ≤ S1 / S2 ≤ 2.8. By controlling the ratio of S1 to S2 within this range, the heat difference between the middle and edge regions of the ceramic plate can be further reduced, resulting in more uniform heating of the entire wafer.

[0016] In the ceramic heater of this application, the auxiliary heating element is disposed in a surrounding manner on the side of the ceramic plate, and the surface of the auxiliary heating element is covered with a glass layer.

[0017] This application incorporates a glass layer, which effectively suppresses heat transfer from the ceramic edge region to the side of the ceramic plate, resulting in more uniform heating of the entire wafer.

[0018] In the ceramic heater of this application, the ceramic heater further includes a first power supply line and a second power supply line, wherein the first power supply line is electrically connected to both ends of the main heating element, and the second power supply line is electrically connected to both ends of the auxiliary heating element.

[0019] In the ceramic heater of this application, the lower surface of the ceramic plate is provided with a first pad and a second pad. The first pad is electrically connected to a first port of the main heating element through a through-hole conductor, and the second pad is electrically connected to a second port of the main heating element through a through-hole conductor. The first power supply line is electrically connected to the first port of the main heating element through the first pad and the through-hole conductor, and the first power supply line is also electrically connected to the second port of the main heating element through the second pad and the through-hole conductor.

[0020] In the ceramic heater of this application, the lower surface of the ceramic plate is provided with a third pad and a fourth pad. The third pad is electrically connected to one end of the auxiliary heating element through a through-hole conductor, and the fourth pad is electrically connected to the other end of the auxiliary heating element through a through-hole conductor. The second power supply line is electrically connected to one end of the auxiliary heating element through the third pad and the through-hole conductor, and the second power supply line is electrically connected to the other end of the auxiliary heating element through the fourth pad and the through-hole conductor.

[0021] In the ceramic heater of this application, the ceramic heater further includes a support body, which is disposed below the ceramic plate. The support body has a hollow cylindrical structure and a power supply is provided inside the support body. The first power supply line and the second power supply line pass through the cavity of the support body and are electrically connected to the power supply. The beneficial effects of this application are as follows: (1) This application provides an auxiliary heating element independent of the main heating element on the side of the ceramic plate, which can effectively reduce the heat deviation between the middle area and the edge area on the ceramic plate bearing surface, greatly improving the overall heating uniformity of the wafer. When the wafer on the bearing heating surface is heated, if the edge area of ​​the ceramic plate has a large heat dissipation, the heat received by the wafer in the edge area is significantly less than that in the middle area. The auxiliary heating element generates heat, effectively suppressing the heat dissipation in the edge area of ​​the ceramic plate, thereby making the overall heating of the wafer uniform; (2) This application forms a rounded corner at the connection between the transition section and the arc section, which can It can effectively prevent stress concentration at the connection due to repeated temperature rise and fall, and thus effectively prevent the collapse of the heating element; (3) In the main heating elements arranged in concentric circles in this application, the distance S1 between two adjacent arc segments in the main heating element is large in the middle area near the ceramic plate (within the area covered by 2R / 3), and the heat generation density in this area is relatively low. In the edge area near the ceramic plate (within the area covered by 2R / 3~R), the distance S2 between two adjacent arc segments in the main heating element is small, and the heat generation density in this area is relatively high, thereby further reducing the heat difference between the middle area and the edge area of ​​the ceramic plate, making the overall heating of the wafer more uniform. Attached Figure Description Figure 1 This is a schematic diagram of the ceramic heater structure of this application; Figure 2 A schematic diagram of the main heating element structure; Figure 3 A magnified structural diagram of the main heating element at point a; Figure 4 This is a left view of the ceramic heating element of this application.

[0022] Reference numerals: 1. Ceramic plate; 101. Wafer mounting surface; 102. Side surface; 103. Lower surface; 2. Main heating element; 201. Arc segment; 202. Transition segment; 203. Rounded corner; 204. First port; 205. Second port; 3. Auxiliary heating element; 4. Glass layer; 5. First power supply line; 6. Second power supply line; 7. First pad; 8. Second pad; 9. Third pad; 10. Fourth pad; 11. Through-hole conductor; 12. Support body; 13. Power supply; 14. Temperature sensor; 141. First temperature sensor; 142. Second temperature sensor; 143. Third temperature sensor; 144. Fourth temperature sensor; 15. Controller. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] The terminology used in this application is for illustrative purposes only and is not intended to limit the scope of this application. Unless otherwise expressly indicated, the singular includes the plural. In this application, terms such as "comprising" or "having" are used to specify the presence of features, numbers, steps, actions, constituent elements, components, or combinations thereof recorded in the specification, and should be understood not to preclude the presence or additional possibilities of one or more other features or numbers, steps, actions, constituent elements, components, or combinations thereof.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0026] The following reference Figures 1-4 The embodiments of this application will be described.

[0027] like Figures 1-4 As shown in the embodiments of this application, the ceramic heater is used to heat the wafer.

[0028] The ceramic heater according to the embodiments of this application includes a ceramic plate 1, a main heating element 2, and an auxiliary heating element 3.

[0029] The ceramic plate 1 includes a wafer mounting surface 101, a side surface 102, and a lower surface 103. The wafer mounting surface 101 is used to mount the wafer, which allows the wafer to be heated. The wafer mounting surface 101 and the lower surface 103 are arranged opposite to each other, and the lower surface 103 is perpendicular to the plane direction of both the wafer mounting surface 101 and the lower surface 103. It should be noted that the diameter of the wafer mounting surface 101 is larger than the diameter of the wafer.

[0030] The main heating element 2 is embedded inside the ceramic plate 1. The main heating element 2 includes multiple arc segments 201 with different radii and multiple transition segments 202. The arc segments 201 and transition segments 202 are alternately arranged and connected end to end in sequence. In this way, the arc segments 201 are connected in series through the transition segments 202. The connection between the transition segment 202 and the arc segment 201 forms a rounded corner 203. This can effectively prevent stress concentration at the connection due to repeated temperature rise and fall, and thus effectively prevent the heating element from collapsing.

[0031] The auxiliary heating element 3 is located on the side of the ceramic plate 1 and is independent of the main heating element 2. This effectively reduces the heat deviation between the middle and edge areas of the ceramic plate bearing surface, greatly improving the overall heating uniformity of the wafer. When the wafer on the bearing heating surface is heated, if the edge area of ​​the ceramic plate 1 experiences greater heat dissipation, resulting in significantly less heat received by the wafer in the edge area compared to the middle area, the auxiliary heating element generates heat, effectively suppressing heat dissipation in the edge area of ​​the ceramic plate, thus ensuring uniform heating of the wafer. Furthermore, the main heating element 2 is arranged in an axisymmetric structure, with the two smallest arc segments forming the first port 204 and the second port 205, respectively, allowing current to flow into the first port 204 and out of the second port 205.

[0032] In some embodiments of this application, such as Figure 2 As shown, the radius of the largest arc segment 201 in the main heating element 2 is R. Within the area covered by 2R / 3 (referring to the area covered by a circle with a radius of 2R / 3), as... Figure 2 Within the dashed circle region, the distance between adjacent arc segments 201 is S1. Within the region covered by 2R / 3~R (referring to the area covered by the circle drawn from the dashed circle to the maximum radius R), the distance between adjacent arc segments 201 is S2, where S1>S2. Thus, in the middle region near the ceramic plate 1 (within the region covered by 2R / 3), the distance S1 between two adjacent arc segments 201 in the main heating element is large, and the heat generation density in this region is relatively low. In the edge region near the ceramic plate 1 (within the region covered by 2R / 3~R), the distance S2 between two adjacent arc segments 201 in the main heating element 2 is small, and the heat generation density in this region is relatively high. This further reduces the heat difference between the middle region and the edge region of the ceramic plate 1, making the overall heating of the wafer more uniform.

[0033] In some embodiments of this application, the ratio of S1 to S2 satisfies: 1.2 ≤ S1 / S2 ≤ 2.8. This further reduces the heat difference between the middle and edge regions of the ceramic plate, making the overall heating of the wafer more uniform.

[0034] Furthermore, the auxiliary heating element 3 is arranged in a surrounding manner on the side of the ceramic plate 1, and the surface of the auxiliary heating element 3 is covered with a glass layer 4. The glass layer 4 can cover the surface of the auxiliary heating element 3 close to the ceramic plate 1 or the surface of the auxiliary heating element 3 away from the ceramic plate 1. In this way, due to the arrangement of the glass layer 4, the heat in the ceramic edge area can be better suppressed from being transferred to the side of the ceramic plate 1, thereby making the overall heating of the wafer more uniform.

[0035] In some embodiments of this application, the ceramic heater mentioned further includes a first power supply line 5 and a second power supply line 6, wherein the first power supply line 5 is electrically connected to both ends of the main heating element 2 and is used to supply power to the main heating element 2, and the second power supply line 6 is electrically connected to both ends of the auxiliary heating element 3 and is used to supply power to the auxiliary heating element 3.

[0036] In some embodiments of this application, the ceramic heater mentioned further includes a first pad 7 and a second pad 8. The first pad 7 and the second pad 8 are respectively disposed on the lower surface 103 of the ceramic plate 1. The first pad 7 is electrically connected to the first port 204 of the main heating element 2 through a through-hole conductor 11, and the second pad 8 is electrically connected to the second port 205 of the main heating element 2 through a through-hole conductor 11.

[0037] More specifically, the first power supply line 5 is electrically connected to the first port 204 of the main heating element 2 through the first pad 7 and the through-hole conductor 11, and the first power supply line 5 is electrically connected to the second port 205 of the main heating element 2 through the second pad 8 and the through-hole conductor 11.

[0038] In some embodiments of this application, the ceramic heater further includes a third pad 9 and a fourth pad 10, which are respectively disposed on the lower surface 103 of the ceramic plate 1. The third pad 9 is electrically connected to one end of the auxiliary heating element 3 through a through-hole conductor 11, and the fourth pad 10 is electrically connected to the other end of the auxiliary heating element 3 through a through-hole conductor 11. The second power supply line 6 is electrically connected to one end of the auxiliary heating element 3 through the third pad 9 and the through-hole conductor 11, and the second power supply line 6 is electrically connected to the other end of the auxiliary heating element 3 through the fourth pad 10 and the through-hole conductor 11.

[0039] In some embodiments of this application, the ceramic heater mentioned further includes a support body 12, which is located below the ceramic plate. The upper end of the support body 12 is connected to the lower surface 103 of the ceramic plate 1. The support body has a hollow cylindrical structure. A power supply 13 is provided inside the support body 12. The first power supply line 5 and the second power supply line 6 pass through the cavity of the support body 12 and are electrically connected to the power supply 13. In this way, the first power supply line 5 can supply power to the main heating element 2, and the second power supply line 6 can supply power to the auxiliary heating element 3.

[0040] In some embodiments of this application, the first pad 7 and the second pad 8 are positioned corresponding to the cavity region of the support 12; the third pad 9 and the fourth pad 10 are positioned in the edge region of the lower surface 103.

[0041] In some embodiments of this application, the ceramic heater mentioned further includes a temperature sensor 14 and a controller 15. The number of temperature sensors 14 can be set to multiple, respectively distributed in the edge area and the middle area of ​​the lower surface 103 of the ceramic plate 1, so that the temperature of different areas of the ceramic plate 1 can be detected. The controller 15 is connected to the temperature sensor 14 and the power supply 13 respectively. The controller 15 can receive signals from the temperature sensor 14. When the temperature difference between the middle area and the edge area of ​​the ceramic plate 1 is too large, the second power supply line 6 is connected by controlling the power supply 13 to make the auxiliary heating element 3 heat up. In this way, the system of this application can be more intelligent. In an unattended environment, the controller 15 can realize whether the auxiliary heating element 3 heats up or not.

[0042] In some embodiments of this application, the controller 15 and the temperature sensor 14 can be connected by a wired electrical connection or a wireless communication connection. Those skilled in the art can use existing connection methods according to actual conditions. In other embodiments of this application, the controller 15 and the temperature sensor 14 are connected by a wireless communication connection.

[0043] In some embodiments of this application, the controller 15 and the power supply 13 can be connected by a wired electrical connection or a wireless communication connection. Those skilled in the art can use existing connection methods according to actual conditions. In other embodiments of this application, the controller 15 and the power supply 13 are connected by a wired electrical connection.

[0044] It is understood that the main material of ceramic plate 1 can be selected from at least one of oxide ceramics (such as alumina, zirconium oxide), nitride ceramics (such as aluminum nitride, silicon nitride, boron nitride), carbide ceramics (such as silicon carbide).

[0045] It is understood that the main heating element 2 and the auxiliary heating element 3 can be made of at least one of the following materials: tungsten, manganese, silver, gold-platinum, niobium, titanium, copper, nickel, or their alloys, or ruthenium-based conductor materials (such as ruthenium oxide, lead ruthenate, etc.). The heating element can be formed by embedding metal wires inside the ceramic plate, or by using processes such as printing, sputtering, or vapor deposition to prepare a metal layer inside the ceramic plate.

[0046] In some embodiments of this application, a groove can be formed inside the ceramic plate by existing conventional means. The size of the groove is sufficient to accommodate the auxiliary heating element. Then, the auxiliary heating element is placed in the groove to fix the auxiliary heating element.

[0047] In other embodiments of this application, the inventors investigated the effects of whether the glass layer 4 is covered, whether the auxiliary heating element 3 is working, and the effects of S1 / S2 on the effect, as follows: Power is supplied to the heater, and the temperature of the heater is controlled at 500°C. The average temperature T1 in the 2R / 3 region and the average temperature T2 in the 2R / 3-R region are detected. The detection method is to detect the temperature at four points equidistant from each other in the radial direction within the region, and then calculate the average temperatures T1 and T2. Then, the temperature difference ΔT between the two regions is calculated as ΔT = T1 - T2. ΔT is required to be within ±1°C. The detection results are shown in Table 1. The working status of the auxiliary heating element is controlled by a controller.

[0048] Table 1

[0049] Comparing Experiment 2 with Comparative Example 1 and Experiment 2 with Comparative Example 2, it can be seen that the auxiliary heating element in this application can effectively improve the uniformity of heating.

[0050] Comparing Experiment 5 with Experiment 2, and Experiment 6 with Experiment 3, it can be seen that the addition of the glass layer further improves the uniformity of heating.

[0051] Comparing Experiments 1-4 with Experiments 7-8, it can be seen that by controlling the ratio of S1 to S2 between 1.2 and 1.8, the uniformity of heating is further improved.

[0052] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the substance and scope of the technical solutions of this application.

Claims

1. A ceramic heater, characterized in that, include: Ceramic plate with wafer mounting surface; The main heating element is disposed inside the ceramic plate; An auxiliary heating element is disposed on the side of the ceramic plate and is independent of the main heating element; The main heating element includes multiple arc segments with different radii and multiple transition segments. The arc segments and transition segments are alternately arranged and connected end to end in sequence, and the connection between the transition segment and the arc segment forms a rounded corner. The radius of the arc segment with the largest radius in the main heating element is R. In the area covered by 2R / 3, the distance between adjacent arc segments is S1. In the area covered by 2R / 3~R, the distance between adjacent arc segments is S2. The ratio of S1 and S2 satisfies: 1.2≤S1 / S2≤2.

8.

2. The ceramic heater according to claim 1, characterized in that, The two arc segments with the smallest radius in the main heating element form a first port and a second port, respectively, so that current flows in from the first port and flows out from the second port.

3. The ceramic heater according to claim 1, characterized in that, The auxiliary heating element is arranged in a surrounding manner on the side of the ceramic plate, and the surface of the auxiliary heating element is covered with a glass layer.

4. The ceramic heater according to claim 2, characterized in that, The ceramic heater also includes a first power supply line and a second power supply line. The first power supply line is electrically connected to both ends of the main heating element, and the second power supply line is electrically connected to both ends of the auxiliary heating element.

5. The ceramic heater according to claim 4, characterized in that, The lower surface of the ceramic plate is provided with a first pad and a second pad. The first pad is electrically connected to the first port of the main heating element through a through-hole conductor. The second pad is electrically connected to the second port of the main heating element through a through-hole conductor. The first power supply line is electrically connected to the first port of the main heating element through the first pad and the through-hole conductor, and the first power supply line is also electrically connected to the second port of the main heating element through the second pad and the through-hole conductor.

6. The ceramic heater according to claim 4, characterized in that, The lower surface of the ceramic plate is provided with a third pad and a fourth pad. The third pad is electrically connected to one end of the auxiliary heating element through a through-hole conductor, and the fourth pad is electrically connected to the other end of the auxiliary heating element through a through-hole conductor. The second power supply line is electrically connected to one end of the auxiliary heating element through the third pad and the through-hole conductor, and the second power supply line is electrically connected to the other end of the auxiliary heating element through the fourth pad and the through-hole conductor.

7. The ceramic heater according to claim 4, characterized in that, The ceramic heater also includes a support body located below the ceramic plate. The support body has a hollow cylindrical structure and a power supply is provided inside the support body. The first power supply line and the second power supply line pass through the cavity of the support body and are electrically connected to the power supply.

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