Heating device

Abstract

1. A heating device (1) comprising a heating plate (2) for heating a workpiece (3), particularly a wafer, within a vacuum chamber (4), the heating plate (2) having a support layer (5) with an upper surface (6), on or above which the workpiece (3) can be placed for heating, the heating device (1) having a heating element (7) for heating the support layer (5) of the heating plate (2), the heating device (1) having mounting arms (9) arranged on edges (8) of the heating plate (2) for mounting the heating plate (2) to support stays (10) within the vacuum chamber (4), the mounting arms (9) each having at least one elastically displaceable spring element (11) and a mounting device (12) for mounting each spring element (11) to each support stay (10).

Description

[Technical Field]

[0001] The present invention relates to a heating device according to the preamble of claim 1 and to a vacuum chamber equipped with such a heating device.

[0002] Heating devices of this kind are known in the prior art. They are used to heat workpieces, such as wafers, thereby bringing them to a temperature required for a subsequent processing step, for example. U.S. Pat. No. 6,551,448 shows a heating device comprising a heating plate for heating the workpiece.

[0003] The object of the present invention is to improve the heating device described at the beginning so that the heating device can particularly well compensate for thermally induced size changes of the heating plate without causing undesirable thermally induced distortions of the heating plate.

[0004] To solve this problem, the invention proposes a heating device as claimed in claim 1.

[0005] Therefore, according to the present invention, it is specified that the heating device has mounting arms arranged on the edges of the heating plate for attaching the heating plate to support stays in the vacuum chamber, and the mounting arms each have at least one elastically displaceable spring element and a mounting device for attaching each spring element to each support stay.

[0006] The mounting arms arranged at the edge of the heating plate, in particular their elastically displaceable spring elements, can compensate for thermally induced changes in the size of the heating plate without undesirable strains occurring in the heating device. The elastically displaceable spring elements are preferably elongated. The elastic displacement of the spring elements preferably occurs transversely to the longitudinal extension direction of the spring elements. Particularly preferably, the elastically displaceable spring elements of the mounting arms are each formed as leaf springs. However, differently configured elastically displaceable spring elements can also be provided. Particularly preferably, one end of each elastically displaceable spring element is attached to the edge of the heating plate, while the opposite end is where the mounting device of the respective mounting arm is located. Particularly preferably, the spring elements are each elastically displaceable in a displacement plane extending parallel to the upper surface of the support layer. However, it is also advantageous if the mounting arms project outward from the heating plate. Each mounting arm may have exactly one resiliently displaceable spring element and exactly one mounting device. However, variations are also possible in which a mounting arm has two resiliently displaceable spring elements, both of which lead to the same mounting device. In general, each mounting arm may have multiple resiliently displaceable spring elements and / or multiple mounting devices.

[0007] The mounting device likewise has a wide variety of possible designs. In a particularly simple design, the mounting device is a mounting eyelet through which the support stay itself or a mounting means, such as a screw or a rivet, can be guided in order to mount the mounting device on the support stay. However, the mounting connection can also be configured as, for example, a clamping connection, a screw connection, and the like.

[0008] The mounting arm may be formed in one piece or in multiple parts. The mounting arm or its resiliently displaceable spring element may be molded integrally with the heating plate. However, it is also possible for the mounting arm or its resiliently displaceable spring element to first be produced as a separate component and then attached to the heating plate by suitable means, such as screwing, riveting, brazing, welding, and the like. The same applies to the connection between the resiliently displaceable spring element and the mounting device.

[0009] In order to be able to carry out the compensation for the above-mentioned temperature-induced size changes, it is particularly preferred that the spring elements each have a spring constant in the range of 30 N / mm to 100 N / mm, preferably 50 N / mm to 80 N / mm, where the spring constant, as is generally known, indicates the ratio of the force acting on the spring element to the resulting displacement of the spring element, where the displacement is preferably measured in a direction perpendicular to or radial to the adjacent edges of the heating plate.

[0010] There are many different possibilities for how the heating element can be configured to heat the support layer of the heating plate and thus also the top surface of the support layer. A particularly preferred embodiment of the present invention specifies that the heating element is planar and is arranged in contact with the support layer on the side opposite the top surface. The heating element may be, for example, a known pressure film heater in which an electric heating element is arranged planarly between two glass plates. This sandwich-shaped heating element is preferably in direct planar contact with the support layer on the side opposite the top surface.

[0011] The heating plate may consist solely of a support layer or may be constructed in multiple layers, particularly if, for example, the heating element is also formed as a separate layer of the heating plate attached to the support layer.

[0012] In any case, it is advantageous if the heating element is an electrically operated heating element. In this case, a particularly preferred embodiment specifies that the power supply lines of the heating device are led to the heating element through at least one duct sealed from the outside. This allows the electrical connections connecting the power supply lines to the heating element to be constantly kept under atmospheric pressure, which helps to avoid electrical flashovers due to the application of a vacuum in the vacuum chamber. The duct sealed from the outside can be led directly to the heating element or can open into a connection chamber sealed from the outside and in which the electrical connections of the heating element are located.

[0013] The support layer is preferably made of steel, but it may also be made of an aluminum alloy or other suitably thermally conductive material.

[0014] Each workpiece to be heated may rest directly on the upper surface of the support layer of the heating plate during the heating process or may be spaced above the upper surface of the support layer of the heating plate.

[0015] The heating plate can have recesses for guiding lifting arms for lifting each workpiece from the upper surface of the support layer of the heating plate or for holding each workpiece above the upper surface of the support layer of the heating plate. In other words, if the workpiece is positioned at some distance above the upper surface of the support layer during the heating process, the workpiece can be placed on the lifting arm. Particularly preferably, the lifting arm is provided with support balls, preferably made of glass, on which the workpiece can be placed.

[0016] The workpiece to be processed is preferably designed in the form of a plate, which may in particular be a so-called wafer.

[0017] The temperature provided by the heating element to the substrate, and in particular to the upper surface of the substrate, is preferably regulated by a corresponding temperature regulation device. In this sense, it is advantageous if the heating device has at least one temperature sensor for measuring the temperature of the substrate on the heating plate. In this case, this temperature value can be supplied as a measured value to a corresponding regulation device of the heating element.

[0018] In addition to the heating device itself, the present invention also relates to a vacuum chamber equipped with at least one heating device according to the present invention, the vacuum chamber having a base plate and preferably at least three support stays protruding from the base plate and arranged spaced apart from one another, the heating plate of the at least one heating device being attached to the support stays, preferably exclusively by a mounting device on a mounting arm. The vacuum chamber may be a pre-chamber, a load lock chamber, or a process chamber. It is particularly preferred that the vacuum chamber is a pre-chamber. The workpiece to be processed is inserted into this pre-chamber under atmospheric pressure, and then a corresponding negative pressure is generated in the closed pre-chamber, during which heating of the workpiece by the heating device can be carried out simultaneously or subsequently. However, the vacuum chamber according to the present invention may also be a process chamber, in which, in addition to heating the workpiece, other processing processes are also carried out on the workpiece.

[0019] Vacuum chambers are generally used when work must be carried out in a specific atmosphere and / or at a specific low pressure level. In particular, they are called vacuum chambers when work is carried out at pressure levels below 0.001 mbar (millibar), i.e., 0.1 Pascal. However, they can also be called vacuum chambers if they are designed for pressures below atmospheric pressure, i.e., below 1 bar.

[0020] A single heating device with a single heating plate may be provided in the vacuum chamber. However, it is also entirely possible for the heating plates of two or more heating devices to be arranged one above the other in the vacuum chamber. Both vacuum valves for opening and closing the vacuum chamber and transport devices for inserting and removing workpieces into and from the vacuum chamber are known per se in the prior art and do not need to be described further here.

[0021] It is advantageously envisaged that the mounting arms provided according to the present invention not only serve to compensate for thermally induced size changes of the heating plate, but also to thermally insulate the heating device from the base plate of the vacuum chamber. In this connection, it is advantageously specified that, during heating by the at least one heating device, a temperature difference of at least 100°C, preferably at least 200°C, occurs between the base plate and the support layer of the heating plate of the at least one heating device. To achieve this value, the mounting arms, and in particular the elastically displaceable spring elements of the mounting arms, may have a correspondingly small cross-sectional area and / or may consist of a suitable material that is also thermally insulating. Numerous means exist for achieving this that can be configured by a person skilled in the art as needed.

[0022] Further features and details of preferred embodiments of the invention will now be described by way of example only with reference to an embodiment. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic longitudinal section of a vacuum chamber according to the invention, comprising two heating devices according to the invention arranged one above the other; [Figure 2] FIG. 2 is a perspective view showing both heating devices shown in FIG. 1 from obliquely above. [Figure 3] FIG. 3 is a plan view of the assembly shown in FIG. 2. [Figure 4] FIG. 3 is an exploded view of FIG. [Figure 5] FIG. 4 is a cross-sectional view taken along the AA cut line in FIG. 3.

[0024] The longitudinal cross-section of the vacuum chamber 4 shown in FIG. 1 is depicted very diagrammatically. Only the base plate 18 and the rest of the housing of the vacuum chamber itself are visible in the cross-section. Neither the vacuum valves for inserting the workpiece 3 into the vacuum chamber 4 nor any exhaust devices, process devices, and the like are shown. These components not shown here may be configured as known in the prior art. The same also applies to the loading robot, which inserts the workpiece 3 into the vacuum chamber 4 and also removes it from the vacuum chamber 4.

[0025] FIG. 1 shows two heating devices 1 according to the present invention, each equipped with a heating plate 2, arranged one above the other. The heating plates 2 each have a support layer 5 with an upper surface 6. For heating, a workpiece 3, for example implemented as a wafer, is placed directly on the respective upper surface 6 of the respective support layer 5 or is arranged at a distance above this upper surface 6 of the support layer 5. The support layer 5 is heated by a heating element 7. In this embodiment, the heating elements 7 are each so-called pressure film heaters, as known per se and already explained at the beginning. The heating elements 7 are each designed as a surface and arranged on the side of the support layer 5 of each heating plate 2 opposite the upper surface 6, in contact with the support layer 5. In addition to the heating devices 1, FIG. 1 also shows a lifting drive plate 19, which is arranged in the vacuum chamber and can be raised and lowered by a known lifting drive 20 (shown only diagrammatically in FIG. 1). The lifting arm 16 is formed on the lifting drive plate 19. These lifting arms 16, together with a lifting drive plate 19, can be raised and lowered by a lifting drive 20. The lifting arms 16 are used, in particular, to place the workpiece 3 on the upper surface 6 of the support layer 5 and to lift it back up from this upper surface 6. This placement occurs when it is desired that the workpiece 3 rests directly on the upper surface 6 of the support layer 5 during the heating process. If it is desired that the workpiece 3 be positioned at some distance above the upper surface 6 of the support layer 5 during the heating process, the workpiece 3 may be placed on the lifting arms 16 at a corresponding distance from the upper surface 6 during the heating process. It is particularly preferred, as will be shown further below, that each of the lifting arms 16 has at least one ball 21, preferably made of glass, on which the workpiece 3 is supported. Also shown in FIG. 1 are support stays 10. As will be described in more detail below, the heating plate 2 is attached to these support stays 10 by its mounting arms 9.

[0026] 1 also shows a line 15 through which a power supply line 14 for the heating elements 7 of each heating device 1, which in the present example are configured as electric heating elements, is guided.

[0027] In the perspective view according to Figure 2, the upper part of the vacuum chamber 4 has now been removed, so that only the base plate 18, the support stay 10 mounted on the base plate 18 and the heating device 1 with the heating plate 2 mounted on the support stay 10 can still be seen.

[0028] In any case, the present invention specifies that each heating device 1 has a mounting arm 9 arranged on each edge 8 of the heating plate 2 for mounting each heating plate 2 to a support stay 10 in the vacuum chamber 4. Each mounting arm 9 in this case has at least one elastically deformable spring element 11 and a mounting device 12 for mounting each spring element 11 to each support stay 10. The elastically deformable spring elements 11 are preferably formed as elongated leaf springs, as shown in FIG. 2 . In the illustrated embodiment, each elastically deformable spring element 11 is integrally formed on each edge of each heating plate 2. At the opposite ends of the elastically deformable spring elements 11 are mounted mounting devices 12, which in this embodiment are formed as simple mounting eyelets. Naturally, other types of mounting devices 12 may be implemented for mounting each mounting arm 9 and thus each heating plate 2 to each support stay 10. This may be, for example, a clamped or screwed connection, or another type of attachment. There are, of course, several different ways of attaching the mounting arms 9 or the resiliently displaceable spring elements 11 to the respective edge 8 of each heating plate 2, different from the embodiment shown here. Instead of integrally molding the mounting arms 9 or the resiliently displaceable spring elements 11, these components can also be screwed, riveted, soldered, welded, and / or otherwise attached to the respective edge of each heating plate 2. FIG. 2 also shows that the mounting arms 9 may be configured in various different ways. The mounting arms 9 shown in the lower right of FIG. 2 each have a single resiliently displaceable spring element 11, with a single mounting device 12 located at the end of this resiliently displaceable spring element 11 opposite the edge 8 of each heating plate 2. The upper left of FIG. 2 shows a variant of the mounting arms 9, in which the mounting device 12 is arranged between and attached to two resiliently displaceable spring elements 11. There are a wide variety of means for this.It should be noted in particular that the elastically displaceable spring element 11 may be formed more or less straight, slightly curved or with an extension shape that is much more rounded or curved than that shown in FIG. 2.

[0029] In any case, it is advantageously specified, as is also realized in the present embodiment, that the spring elements 11 are each elastically displaceable in a displacement plane 13 which extends parallel to the upper surface 6 of the support layer 5. The position of the displacement plane 13 is depicted diagrammatically in Figure 1. It is also advantageous, as is also realized in the present embodiment, if the mounting arms 9 each project outwardly from the heating plate 2.

[0030] Also visible in FIG. 2 are measuring feelers 17 attached to the corresponding support layers 5 of each heating plate 2, respectively, for measuring the temperature of the support layers 5 thereof.

[0031] For completeness, it is pointed out again here that either only one heating device 1 according to the invention or two or more heating devices 1 according to the invention may be arranged in the vacuum chamber 4 according to the invention. If two or more heating devices 1 according to the invention are provided, they are advantageously arranged one above the other in the vacuum chamber 4, as also shown in FIG.

[0032] In FIG. 2, a workpiece 3 is placed on the upper surface 6 of each of the support layers 5 of each of the heating plates 2. In this embodiment, this may be, for example, a wafer or other plate-like workpiece 3. However, the workpiece 3 is not shown in the plan view of FIG. 3. In FIG. 3, as in the exploded view of FIG. 4, it is clearly visible that the heating plates 2 each have a notch 22 for guiding the lifting arm 16 therethrough. Also visible in FIG. 3 is a ball 21, preferably a glass ball, on the lifting arm 16. It is advantageously specified that each workpiece 3 is placed exclusively on the lifting arm 16 with the ball 21 interposed therebetween. When the lifting arm 16 is lowered a corresponding distance by the lifting drive 20, the workpiece 3 is placed directly on the upper surface 6 of the support layer 5.

[0033] FIG. 4 shows the assembly shown in FIG. 2 again in an exploded view, in which the individual components already described can be particularly well seen.

[0034] Figure 5 shows a cross-section of the externally sealed duct 15 provided in this embodiment, taken along the line AA in Figure 3. The power supply lines 14 for operating each electrically operated heating element 7 are guided through this duct 15. Figure 5 shows how the electrical supply lines 14 are connected to the electrical heating elements 7 by electrical connection points 24. In Figure 5, the electrical connection points 24 are located in externally sealed connection chambers 25, into which the externally sealed duct 15 is introduced. Alternatively, however, the duct 15 can also be guided directly to the electrical connection points 24, thereby eliminating the need for a corresponding connection chamber 25.

[0035] For completeness, it should also be pointed out that, as shown in Figure 5, the line 15 may be formed partly as a bellows hose 23. Such a bellows hose 23 makes it possible to compensate for thermally induced expansion and displacement of the line 15. [Explanation of symbols]

[0036] 1 Heating device 2 heating plates 3 Workpiece 4. Vacuum chamber 5 Support layer 6 Top side 7 Heating element 8 Edge 9 Mounting Arm 10 Support stay 11 Spring elements 12 Mounting device 13 Displacement Plane 14 Power supply line 15 Conduit 16 Lifting arm 17 Temperature sensor 18 Base Plate 19 Lifting drive plate 20 Lifting drive device 21 Ball 22 Notch 23 Bellows hose 24 Electrical Connections 25 Connection Chamber

Claims

1. A heating device (1) comprising a heating plate (2) for heating a workpiece (3), in particular a wafer, in a vacuum chamber (4), the heating plate (2) has a support layer (5) with an upper surface (6) on or above which the workpiece (3) can be placed for heating; The heating device (1) has a heating element (7) for heating the support layer (5) of the heating plate (2). In the heating device (1), The heating device (1) has mounting arms (9) arranged on the edge (8) of the heating plate (2) for mounting the heating plate (2) to a support stay (10) in the vacuum chamber (4), The mounting arms (9) each have at least one elastically displaceable spring element (11) and a mounting device (12) for mounting each of the spring elements (11) to each of the support stays (10). A heating device (1) characterized in that:

2. 2. The heating device (1) according to claim 1, characterized in that the spring elements (11) are each elastically displaceable in a displacement plane (13) extending parallel to the upper surface (6) of the support layer (5).

3. 3. Heating device (1) according to claim 1 or 2, characterized in that the mounting arms (9) project outwardly from the heating plate (2).

4. Heating device (1) according to any one of claims 1 to 3, characterized in that the spring elements (11) each have a spring constant in the range of 30 N / mm to 100 N / mm, preferably 50 N / mm to 80 N / mm.

5. 5. The heating device (1) according to claim 1, wherein the heating element (7) is formed in a planar shape and is arranged in contact with the support layer (5) on the side of the support layer (5) opposite the upper surface (6).

6. 6. The heating device (1) according to claim 1, wherein the heating element (7) is an electrically operated heating element (7) and the power supply line (14) of the heating device (1) is guided to the heating element (7) through at least one pipe (15) sealed against the outside.

7. 7. The heating device (1) according to claim 1, wherein the heating plate (2) has a notch (22) for guiding a lifting arm (16) for lifting each of the workpieces (3) from the upper surface (6) of the support layer (5) of the heating plate (2) or for holding each of the workpieces (3) above the upper surface (6) of the support layer (5) of the heating plate (2), and / or the heating device (1) has at least one temperature sensor (17) for measuring the temperature of the support layer (5) of the heating plate (2).

8. 8. A vacuum chamber (4) comprising at least one heating device (1) according to any one of claims 1 to 7, the vacuum chamber (4) having a base plate (18) and preferably at least three support stays (10) protruding from the base plate (18) and arranged spaced apart from one another, the heating plate (2) of the at least one heating device (1) being attached to the support stays (10) preferably exclusively by the attachment devices (12) of the attachment arms (9).

9. 9. Vacuum chamber (4) according to claim 8, characterized in that in the vacuum chamber (4) the heating plates (2) of two or more heating devices (1) are arranged one above the other.

10. 10. The vacuum chamber (4) according to claim 8 or 9, characterized in that, when heated by the at least one heating device (1), a temperature difference of at least 100°C, preferably at least 200°C, occurs between the base plate (18) and the support layer (5) of the heating plate (2) of the at least one heating device (1).

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