Substrate heating device and load lock chamber including substrate heating device

Abstract

To provide a substrate heating device that can heat a substrate with excellent in-plane uniformity irrespective of the heating temperature thereof when heating a substrate having a rectangular contour in a heating chamber.SOLUTION: When directions orthogonal to each other within a surface of a substrate are an X axis direction and a Y axis direction, a plurality of rod-like lamp heaters 2 longer than a length in the Y axis direction of the substrate is arrayed at predetermined intervals in the X axis direction while facing one surface of the substrate. The surface of the substrate is sectioned into at least three regions in the X axis direction which include: a center region Cz in which lamp heaters 2a positioned on both end sides in the X axis direction are positioned outward from both ends in the X axis direction and which includes a substrate center Sc therein; and peripheral regions Sz1, Sz2 of which areas are smaller than the area of the center region on both sides in the X axis direction of the center region. When respective lamp heaters facing the center region are center lamp groups 21, and respective lamp heaters facing the peripheral regions, respective lamp heaters positioned outward from both ends in the X axis direction of the substrate are lateral lamp groups 22, 23, respective lamps of the lateral lamp groups operate at a lamp output equivalent to or higher than that of the center lamp group.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a substrate heating apparatus for heating a substrate having a rectangular profile within a heating chamber, and a load lock chamber including the substrate heating apparatus. [Background technology]

[0002] In the manufacturing process of flat panel displays, a rectangular glass substrate (hereinafter referred to as "substrate") is preheated to a predetermined temperature prior to the deposition of various thin films on its surface. The preheating process is sometimes performed in a load lock chamber connected to a process chamber where film deposition is performed via a gate valve. The load lock chamber is equipped with a substrate heating device for heating the substrate. The size of the substrate on which film deposition is performed has increased with each generation (e.g., 2300 mm × 2700 mm for the G8.7 generation) and its thickness has also decreased (e.g., 0.5 mm). Known substrate heating devices for preheating such substrates to a predetermined temperature range (e.g., 50°C to 200°C) in a short time include those using lamp heaters such as halogen lamps. Specifically, the X-axis and Y-axis directions are orthogonal to each other within the substrate plane. The substrate heating device generally comprises a plurality of rod-shaped lamp heaters, each longer than the length of the substrate in the Y-axis direction, arranged at equal intervals in the X-axis direction and facing one side of the substrate (see, for example, Patent Document 1). At this time, the lamp heaters at both ends in the X-axis direction are arranged so as to be positioned above both edges of the substrate in the X-axis direction.

[0003] The amount of heat radiated onto the substrate during heating depends on the lamp output of each lamp heater (power density: W / m 2 / k), but also depends on the directionality of light irradiation from the lamp heater to the substrate. Therefore, with the lamp heaters arranged as in the conventional example, the amount of heat irradiated to the substrate at both ends in the X-axis direction is reduced, and the substrate may only be heated to a lower temperature than the central region. This makes it impossible to achieve a substantially uniform substrate temperature (e.g., ±5°C) across the substrate surface. In such cases, it is possible to use lamp heaters with high lamp output that are arranged opposite the both end regions in the X-axis direction of the substrate. However, it has been found that when the substrate temperature to be heated is relatively low, the both end regions in the X-axis direction of the substrate become locally high in temperature. In other words, the temperature at which the substrate is preheated varies depending on the film material to be formed in the subsequent process (e.g., 50°C for an Al film and 200°C for a Mo film). However, when the substrate is heated to a relatively low temperature, the both end regions in the X-axis direction of the substrate become locally high in temperature. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-140684 Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above, an object of the present invention is to provide a substrate heating device and a load lock chamber equipped with a substrate heating device that can maintain a substantially uniform substrate temperature across the substrate surface at all times, regardless of the temperature of the substrate to be heated. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a substrate heating apparatus for heating a rectangular substrate within a heating chamber, the apparatus comprising: an X-axis direction and a Y-axis direction that are orthogonal to each other within the substrate plane; a plurality of rod-shaped lamp heaters, each longer than the length of the substrate in the Y-axis direction, arranged in a row at intervals in the X-axis direction facing one side of the substrate; the lamp heaters located at both ends in the X-axis direction are located outward from both ends of the substrate in the X-axis direction; the substrate plane is divided into at least three regions in the X-axis direction: a central region inward from the center of the substrate; and peripheral regions on both sides of the central region in the X-axis direction and smaller in area than the central region; the lamp heaters facing the central region are referred to as a central lamp group; and the lamp heaters facing the peripheral regions and the lamp heaters outward from both ends of the substrate in the X-axis direction are referred to as side lamp groups, the lamp heaters in the side lamp groups operating with a lamp output equal to or greater than that of the central lamp group. The present invention also provides a load lock chamber defining the heating chamber, the apparatus comprising: a substrate setting table on which a substrate is placed; and the substrate heating apparatus having the above-described features.

[0007] Through extensive research, the inventors of the present invention have discovered the following. Specifically, when lamp heaters with a predetermined lamp output are selected based on the maximum heating temperature within the substrate's heating temperature range, and multiple lamp heaters are arranged in a row as in the conventional example, the regions at both ends of the substrate in the X-axis direction can only be heated to a lower temperature than the central region of the substrate, regardless of the heating temperature. Next, by defining the distance in the X-axis direction between the lamp heaters facing the central region as the lamp pitch, and adding at least one lamp heater with a lamp pitch equal to or smaller than the lamp pitch outside both ends of the substrate in the X-axis direction, it has been discovered that when the substrate heating temperature is relatively low (e.g., 50°C), the substrate can be heated to a substantially uniform temperature across the substrate. On the other hand, when the substrate heating temperature is relatively high (e.g., 100°C), the regions at both ends of the substrate in the X-axis direction can only be heated to a lower temperature than the central region of the substrate.

[0008] Based on this knowledge, the present invention divides the substrate surface into at least three regions in the X-axis direction: a central region and peripheral regions on both sides of the central region. Each lamp heater in the side lamp group operates with a lamp output equal to or greater than that of the central lamp group. This allows for a substantially uniform substrate temperature across the substrate surface at all times, regardless of the substrate temperature being heated. Lamp heaters, such as halogen heaters, typically have a lamp output that can be adjusted within a predetermined range by adjusting the input power. Therefore, by selecting lamp heaters based on the lamp output control range and the maximum heating temperature in the peripheral region of the substrate, the same type of lamp heater can be used for the substrate heating device (in other words, there is no need to use lamp heaters of a different type for the side lamp group than for the central lamp group, allowing for component sharing), which is advantageous in terms of cost, etc. Furthermore, the width of the peripheral region in the X-axis direction can be determined experimentally in advance.

[0009] Furthermore, through intensive research by the inventors, it was found that when the heating temperature of the substrate becomes even higher (e.g., 150°C or higher), a temperature gradient also occurs in the peripheral region of the substrate (i.e., the temperature decreases toward each end of the substrate). Therefore, in the present invention, the peripheral region is further divided into multiple small regions in the X-axis direction depending on the heating temperature when the substrate is heated in the heating chamber, and one of the adjacent small regions located in the central region is designated as a first peripheral region, and the other is designated as a second peripheral region, and the lamp heaters of the side lamp group facing the second peripheral region operate at a lamp output equal to or greater than that of the lamp heaters of the side lamp group facing the first peripheral region. This allows the substrate temperature to be kept approximately uniform across the substrate surface at all times, regardless of the substrate temperature to be heated, even when a relatively wide-area substrate is heated.

[0010] However, even if the length of the lamp heater in the Y-axis direction is set longer than the substrate and the lamp heaters protrude from both ends of the substrate in the Y-axis direction, the amount of heat radiated onto the substrate at both ends of the Y-axis direction may be reduced, resulting in the substrate only being heated to a lower temperature than the central region of the substrate. Therefore, in the present invention, it is preferable to further provide a strip-shaped reflector plate disposed opposite the other surface of the substrate and straddling each of the two sides of the substrate extending in the X-axis direction. This allows the light reflected by the reflector plate to heat the both ends of the substrate in the Y-axis direction, thereby making the substrate temperature more uniform across the substrate surface. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a schematic cross-sectional view of a load lock chamber of the present embodiment equipped with the substrate heating device of the present embodiment. [Figure 2] Cross-sectional view along line II-II in Figure 1. [Figure 3] 10 is a graph showing experimental results of lamp output required to heat a substrate surface to a predetermined temperature. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, with reference to the drawings, an embodiment of a substrate heating device SH and a load lock chamber LC equipped with the substrate heating device SH of the present invention will be described, taking as an example a case where a glass substrate (hereinafter referred to as "substrate Sg") of a predetermined size and having a rectangular outline is heated to a predetermined temperature range in a load lock chamber. Hereinafter, the directions orthogonal to each other in the plane of the substrate Sg are referred to as the X-axis direction and the Y-axis direction, and the direction orthogonal to the X-axis direction and the Y-axis direction is referred to as the Z-axis direction. The terms indicating directions are based on FIG. 1, which shows the load lock chamber LC in its installed position.

[0013] Referring to FIG. 1 , a load lock chamber LC, which is connected via a gate valve Gv to a process chamber Pc for performing various vacuum processes such as film formation and etching, has a gas inlet 11 and an exhaust port 12 in its wall. A gas inlet pipe 13 with a vent valve 13a is connected to the gas inlet 11, leading to a gas source (not shown) such as nitrogen gas. An exhaust pipe 14 with an on-off valve 14a is connected to the exhaust port 12, leading to a vacuum pump (not shown), enabling the interior of the load lock chamber LC to be quickly switched between atmospheric and vacuum. A substrate mounting stage 15 having an upper surface 15a with an area slightly larger than the outline of a substrate Sg is provided within the load lock chamber LC. In this embodiment, the upper surface of the substrate mounting stage 15 is provided with multiple support pins 15b protruding upward in the Z-axis direction, and the substrate Sg is supported by the upper ends of each support pin 15b. Opposite to the substrate Sg placed on the substrate placement table 15, the substrate heating device SH of this embodiment is disposed above the load lock chamber LC, which also serves as the heating chamber LC1.

[0014] Referring also to FIG. 2, the substrate heating device SH is configured by arranging a plurality of rod-shaped lamp heaters 2, each longer than the length of the substrate Sg in the Y-axis direction, at intervals in the X-axis direction. Each lamp heater 2 is of the same type, and for example, a halogen heater is used, which has a structure in which a filament such as tungsten is provided in the Y-axis direction within a tube (bulb) such as glass, and halogen gas and inert gas are sealed within the tube. In this case, the lamp heater 2 is selected to have a predetermined lamp output based on the maximum heating temperature within the heating temperature range when heating the substrate Sg, and the lamp output (output density: W / m) from each lamp heater 2 is set. 2 / k), infrared light is emitted radially. As known lamp heaters can be used as such lamp heaters 2, further explanation, including the power source for energizing them, will be omitted. In this embodiment, one lamp heater 2 is arranged at a position facing the Y-axis line passing through the substrate center Sc, and other lamp heaters 2 are arranged at a constant lamp pitch Rp1 on both sides of this lamp heater 2 in the X-axis direction at a starting point. The lamp heaters 2 at both ends of the X-axis direction (hereinafter, these will be referred to as "lamp heaters 2a, 2a") are positioned outward from both ends of the substrate Sg in the X-axis direction. The lamp pitch Rp1 is determined by the lamp output (power density: W / m 2 / k) and the directionality of light irradiation from each lamp heater 2 to the substrate Sg. The lamp pitch Rp2 between each lamp heater 2a, 2a at both ends in the X-axis direction and the lamp heater 2, 2 adjacent thereto in the X-axis direction is set to the same as the lamp pitch Rp1, but can also be set shorter than the lamp pitch Rp1 depending on the amount of heat irradiated at both ends of the X-axis direction of the substrate Sg, and multiple lamp heaters can also be arranged outward from both ends of the X-axis direction of the substrate Sg.

[0015] Here, a G8.7 generation glass substrate was prepared as the substrate Sg, and this glass substrate was transported to the load lock chamber LC and placed on the upper surface of the substrate placement table 15 while being supported by each support pin 15b. An experiment was carried out in which the glass substrate was heated to target temperatures (50°C and 150°C) in the load lock chamber LC in a vacuum atmosphere. At this time, the temperature was measured at multiple points between the substrate center Sc and the substrate edge Se in the X-axis direction, and the lamp output (W / m) of each lamp heater 2 when the temperature at each measurement point reached approximately 50°C or approximately 150°C was calculated. 2 / K) was calculated for each measurement point. Figure 3 is a graph showing the lamp output of each lamp heater 2 for each measurement point, with ● representing the target temperature of 50°C and ◯ representing the target temperature of 150°C. This shows that, within a predetermined range from the substrate center Sc to the substrate edge Se (i.e., a relatively wide range including the substrate center Sc), the lamp output of each lamp heater 2 can be equal regardless of the target temperature to be heated. Furthermore, when the target temperature is 50°C, by arranging the lamp heaters 2a, 2a outward from both ends of the substrate Sg in the X-axis direction, it was found that the lamp output of each lamp heater 2 can be equal throughout the entire range from the substrate center Sc to the substrate edge Se. On the other hand, when the glass substrate is heated to a relatively high target temperature of 150°C, it was found that the lamp output needs to be increased as it approaches the substrate edge Se. This is thought to be because the amount of heat irradiated onto the substrate Sg in the regions at both ends in the X-axis direction is smaller, and because heat is radiated onto the wall surfaces of the load lock chamber LC adjacent to both ends of the substrate Sg in the X-axis direction, making it more difficult for the regions at the outer edge of the substrate Sg to rise in temperature the higher the target temperature.

[0016] Based on the above findings, in this embodiment, the surface of the substrate Sg facing the substrate heating device SH is divided into five regions: a central region Cz inward from the substrate center Sc (in other words, a relatively wide region in the center of the substrate where the lamp outputs of the lamp heaters 2 can be equal regardless of the target temperature), first peripheral regions Sz1 as subdivided regions on both sides of the central region Cz in the X-axis direction and having smaller areas than the central region Cz (in other words, regions requiring higher lamp outputs than the lamp heaters 2 in the central region), and a second peripheral region Sz2 as a subdivided region on the outer side of the first peripheral region Sz1 in the X-axis direction and having an area equivalent to that of the first peripheral region Sz1 (in other words, regions requiring higher lamp outputs than the lamp heaters 2 in the first peripheral region Sz1). The lamp heaters 2 facing the central region Cz are designated as a central lamp group 21, the lamp heaters 2 facing the first peripheral region Sz1 are designated as a first side lamp group 22, and the lamp heaters 2 facing the second peripheral region Sz2 are designated as a second side lamp group 23, and each lamp heater 2 in the first side lamp group 22 operates with a lamp output equal to or greater than that of the central lamp group 21, and each lamp heater 2 in the second side lamp group 23 operates with a lamp output equal to or greater than that of the first side lamp group 22.

[0017] Even if the length of each lamp heater 2 in the Y-axis direction is set longer than that of the substrate Sg and the lamp heaters 2 are arranged to protrude from both ends of the substrate Sg in the Y-axis direction, as in this embodiment, it has been found that, for example, the amount of heat irradiated onto the substrate Sg at both ends of the Y-axis direction is reduced, and the substrate Sg can only be heated to a lower temperature than the central region of the substrate Sg. In this embodiment, a strip-shaped reflector plate 3 is provided on the upper surface of the substrate mounting table 15 (i.e., arranged facing the other side of the substrate Sg) so as to straddle two sides of the substrate Sg extending in the X-axis direction in the Y-axis direction. For example, considering cost, the reflector plate 3 is made of metal foil made of gold, copper, or aluminum with a predetermined thickness (several mm) that has a high reflectivity for infrared light. In this case, it is preferable to arrange multiple metal foil pieces 3a with a short length in the X-axis direction in a row to reduce the influence of thermal deformation when the reflector plate 3 is heated.

[0018] According to the above embodiment, even when a substrate Sg having a relatively wide range and large area is heated, the substrate temperature can be kept substantially uniform across the substrate surface at all times, regardless of the substrate temperature to be heated. Since the lamp heaters 2 are of the same type (same shape), this is advantageous in terms of cost, etc. Furthermore, since the reflector plate 3 is provided and light reflected by the reflector plate 3 also heats the regions on both ends of the substrate Sg in the Y-axis direction, the substrate temperature can be made more uniform across the substrate Sg.

[0019] Although the above describes an embodiment of the present invention, various modifications are possible without departing from the scope of the technical concept of the present invention. In the above embodiment, the substrate Sg is divided into five regions: a central region Cz, a first peripheral region Sz1, and a second peripheral region Sz2. However, this is not limited to this. If the temperature range to which the substrate Sg is to be heated is narrow, the peripheral region need not be further divided into smaller regions. Instead, it can be divided into three regions: a central region Cz and two peripheral regions on either side of the central region Cz in the X-axis direction. On the other hand, the peripheral region can also be divided into three or more regions, and the width of each of the smaller regions in the X-axis direction can be appropriately set. Furthermore, in the above embodiment, a halogen lamp was used as the lamp heater 2, but this is not limited thereto and other known lamp heaters may also be used. Furthermore, in the above embodiment, the substrate heating device SH was installed in a load lock chamber LC. However, this is not limited thereto and the present invention can be widely used, such as heating the substrate Sg in a film formation chamber Pc. [Explanation of symbols]

[0020] SH...substrate heating device, LC...load lock chamber, LC1...heating chamber, 15...substrate placement table, 15a...top surface of substrate placement table, 2, 2a...lamp heater body, 21...central lamp group, 22, 23...side lamp groups, 3...reflector plate, Sg...substrate, Cz...central region, Sz1...first peripheral region (divided region), Sz2...second peripheral region (divided region).

Claims

1. 1. A substrate heating apparatus for heating a substrate having a rectangular contour within a heating chamber, comprising: The X-axis direction and the Y-axis direction are mutually orthogonal directions within the substrate surface, and a plurality of rod-shaped lamp heaters, each longer than the length of the substrate in the Y-axis direction, are arranged in a row at intervals in the X-axis direction, facing one surface of the substrate, The lamp heaters located on both ends in the X-axis direction are located outward from both ends of the substrate in the X-axis direction, The substrate surface is divided into at least three regions in the X-axis direction: a central region located inward from the center of the substrate; and peripheral regions located on both sides of the central region in the X-axis direction and having an area smaller than that of the central region. A substrate heating device characterized in that the lamp heaters facing the central region are defined as a central lamp group, and the lamp heaters facing the peripheral region and the lamp heaters outward from both ends of the substrate in the X-axis direction are defined as side lamp groups, and each lamp heater in the side lamp groups is configured to operate with a lamp output equal to or greater than that of the central lamp group.

2. A substrate heating device characterized in that the peripheral area is further divided into a plurality of subdivided areas in the X-axis direction depending on the heating temperature when the substrate is heated in the heating chamber, one of the adjacent subdivided areas located in the central area is designated as a first peripheral area, and the other is designated as a second peripheral area, and the lamp heaters of the side lamp group facing the second peripheral area are configured to operate with the same or higher lamp output as the lamp heaters of the side lamp group facing the first peripheral area.

3. 3. The substrate heating device according to claim 2, further comprising a strip-shaped reflector plate disposed opposite the other surface of the substrate and straddling two sides of the substrate extending in the X-axis direction.

4. 4. A load lock chamber defining the heating chamber, comprising: a substrate placement stage on which a substrate is placed; and a substrate heating device according to claim 1.

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