Heating elements for substrate processing systems

Abstract

The present invention relates to a heating element, a substrate processing system including such a heating element, and a method for processing substrates in such a substrate processing system. The heating element includes a conductive electrode extending along a path between an input contact and an output contact. The conductive electrode includes a segment along the path where the conductive electrode divides into at least two separate conductive electrode branches electrically connected in parallel. The conductive electrode and the at least two separate conductive branches include a heat-generating component configured to generate heat and / or emit thermal radiation when an electric current is passed through the heat-generating component.

Description

[Technical Field]

[0001] The present invention relates to a heating element, a substrate processing system including such a heating element, and a method for processing a substrate using such a substrate processing system. In particular, the present invention relates to a heating element including conductive electrodes extending between input and output contacts, the conductive electrodes extending along paths for providing a circuit pattern, the conductive electrodes including heat-generating components, and the paths configured to provide optimized heat generation performance. [Background technology]

[0002] The pattern design of the conductive electrodes and / or the placement of the heat-generating components of the heating element directly affects the performance of the heating element, most importantly the temperature uniformity across the area of ​​the heating element. Poor uniformity in the heat generated by a heating element in a substrate processing system results in significant heating variations across the substrate, making it impossible to heat the substrate uniformly.

[0003] For example, U.S. Patent Application Publication No. 2008 / 0029195 discloses a wafer processing apparatus having an optimized electrode pattern for a resistive heating element. The optimized electrode pattern is designed to generate more heat near or around contact areas, electrical connections, through-holes, etc., thereby compensating for heat loss around these areas and thereby providing maximum temperature uniformity. In addition, U.S. Patent Application Publication No. 2008 / 0029195 teaches the use of a multi-zone heater pattern with different geometries and specifications for each zone to achieve a uniform heater temperature distribution.

[0004] Alternatively, U.S. Patent Application Publication No. 2021 / 0398829 discloses a substrate support for a substrate processing system configured to perform a deposition process on a substrate. The substrate support includes a pedestal having an upper surface configured to support a substrate and multiple heating layers vertically stacked within the pedestal below the upper surface. Each of the multiple heating layers includes a respective resistive heating element in the form of a resistive coil. In at least one of the heating layers, the pitch of the resistive coil in a radial zone of the substrate support is different from the pitch of the resistive coil in other radial zones of the substrate support. Thus, the watt density of the resistive heating element in at least one heating layer varies in the radial zone compared to the other radial zones of the substrate support. By arranging different coils having different geometries in the various heating layers and / or individually controlling the power supplied to the various heating layers, non-uniformity in the temperature distribution across the upper surface of the pedestal can be reduced.

[0005] Both of the above prior art documents recognize the problem of heat loss at the periphery of the heater. According to US Patent Application Publication No. 2008 / 0029195, this heat loss can be compensated for by using narrower outermost electrode paths for more localized heating. According to US Patent Application Publication No. 2021 / 0398829, this heat loss can be compensated for by increasing the heat generation in the outer zones using more densely packed coils of the heating element in the outer zones. Summary of the Invention [Problem to be solved by the invention]

[0006] It is an object of the present invention to provide a heating element with an alternative method of varying the heat output in different regions of the heating element. [Means for solving the problem]

[0007] According to a first aspect, the present invention relates to a heating element for a substrate processing system, the heating element including a conductive electrode extending along a path between an input contact and an output contact, the conductive electrode including a segment along the path where the conductive electrode divides into at least two separate conductive electrode branches electrically connected in parallel, the conductive electrode and the at least two separate conductive branches each including a heat-generating component configured to generate heat and / or emit thermal radiation when an electric current is flowing through the heating element.

[0008] In the heating element of the present invention, the conductive electrode includes a segment in which the electrode is divided into at least two separate conductive electrode branches electrically connected in parallel. As a result, at the division point, the total current through the conductive electrode is distributed to the at least two separate conductive electrode branches depending on the electrical resistance of the separate conductive electrode branches relative to each other. For example, when the electrode is divided into two separate electrode branches, and the electrical resistance of the two electrode branches is substantially equal, the total current through the conductive electrode is distributed so that the current through each of the two electrode branches is substantially half of the total current. Because the power generated by the heating element is a function of the current through the heating element, the power generated by the heating element disposed on the conductive electrode before division will be higher than the power generated by the heating element disposed on each of the separate conductive electrode branches after division.

[0009] Thus, in the heating element of the present invention, the power generated in different portions of the conductive electrode is varied by dividing the current through the conductive electrode into at least two separate conductive electrode branches electrically connected in parallel. The different portions particularly refer to the conductive electrode portion on the outside of the segment and the portion inside the segment where the conductive electrode is divided into at least two separate conductive electrode branches electrically connected in parallel. Because the power generated is a function of the current through the conductive electrode, the variation in the power generated can be much greater than when using only the variation in the resistance of the heating element, as described in, for example, U.S. Patent Application Publication No. 2008 / 0029195, or when using more densely packed heating coils, as described in, for example, U.S. Patent Application Publication No. 2021 / 0398829.

[0010] When processing substrates at very high temperatures, achieving uniform heating becomes more difficult. Higher temperatures generally result in greater heat dissipation, leading to greater temperature non-uniformities. Due to the potential for large variations in the power generated at different portions of the conductive electrode, the heating element of the present invention is particularly suitable for substrate processing systems for processing substrates at higher temperatures, for example, for growing two-dimensional graphene layers on substrates at temperatures in the range of 600°C to 1300°C, particularly at or around 1000°C.

[0011] In one embodiment, the heat generating component extends along the conductive electrode. In one embodiment, the heat generating component extends substantially the entire length of the conductive electrode. Thus, the heat generating component is distributed along at least a portion of the path, preferably substantially the entire length of the path of the conductive electrode, which results in a more uniform distribution of heat generated along the path.

[0012] In one embodiment, the heat generating component comprises an electrical resistance heating component. Because the power generated by an electrical resistance heating component is quadratically related to the current through the resistance heating component, the power generated in the resistive heating component of the conductive electrode before splitting can be as high as four times the power generated in the resistive heating component of each of the conductive electrode branches after splitting (assuming the conductive electrode is split into two separate electrode branches and the resistance of each of the separate conductive electrode branches is substantially equal).

[0013] In one embodiment, the pathway is arranged in a plane, preferably a substantially flat plane, making the heating element according to this embodiment particularly suitable for use in substrate processing systems for processing substantially flat substrates, such as thin silicon wafers or thin sapphire plates.

[0014] In one embodiment, the electrical resistance heating element includes a cross-sectional area in a direction substantially transverse to a direction along a path from the input contact to the output contact, the cross-sectional area varying along the path. Because the generated power is inversely proportional to the cross-sectional area of ​​the electrical resistance heating element, a method is provided for varying the heating power along the path of the conductive electrode by varying the cross-sectional area along the path, which method can be used to fine-tune large variations in generated power resulting from the division of the conductive electrode into at least two separate conductive electrode branches electrically connected in parallel, in order to optimize the resistive heating element to provide optimal uniform heating of the substrate in a particular application.

[0015] In one embodiment, the thickness of the electrical resistance heating element in a direction perpendicular to the plane is substantially constant, and the width of the electrical resistance heating element in a direction parallel to the plane varies along the path. This embodiment offers the same fine tuning possibilities as the previous embodiment, and additionally allows the cross-sectional area to be varied in a less complicated way by simply varying the width of the electrical resistance heating element along its path and keeping the thickness of the electrical resistance heating element substantially constant.

[0016] In one embodiment, the heating element includes an edge, preferably a peripheral edge, and the conductive electrode includes a first section adjacent the edge and a second section, the first and second sections being electrically connected in series, the first section being disposed between the edge and the second section, and the second section of the conductive electrode including a segment along which the conductive electrode is divided into at least two separate conductive electrode branches electrically connected in parallel. The first section does not include a segment along which the conductive electrode is divided into at least two separate conductive electrode branches electrically connected in parallel, and therefore, in use, the total current flows through the conductive electrode in the first section, which results in a relatively high heat output in the first section to compensate for heat losses at the edge of the planar surface.

[0017] In one embodiment, the first section provides an outer ring that substantially surrounds the second section of the heating element. Therefore, compensation for heat loss at the edges of the heating element is achieved over substantially the entire circumference of the heating element. The second section is located in the inner zone of the heating element. In the inner zone, heat loss to the surrounding environment is much less than heat loss at the periphery. Therefore, to adjust the uniformity of heat generation in the inner zone, it is not necessary to generate such high heat output, and the conductive electrode in the inner zone can be divided into at least two separate conductive electrode branches electrically connected in parallel. In one embodiment, the temperature profile in the inner zone is fine-tuned using the above-described variation in the width of the electrical resistance heating element, particularly the width of the conductive heating element in each of the at least two separate conductive electrode branches.

[0018] In one embodiment, the conductive electrode includes two first and second sections electrically connected in series, with the second section positioned between the two first sections, each of which is positioned adjacent to opposing edges, with the opposing edges being positioned on the side of the first section facing away from the second section. In an embodiment in which the heating element has a circular shape, the two first sections each provide a portion of an outer ring that substantially surrounds the second section of the heating element. Preferably, the heating element includes the following connected in series behind each other: an input contact, a first section providing a portion of the outer ring, a second section located in an inner region of the outer ring and including at least two separate conductive electrode branches, a first section providing the remainder of the outer ring, and an output contact. This embodiment provides the same advantages as the previous embodiment, and additionally allows the input and output contacts to be located at or near the periphery so that the heating element can be easily connected to a power source.

[0019] In one embodiment, the second section is substantially completely divided into at least two separate conductive electrode branches electrically connected in parallel, so that the current in the conductive electrodes is divided behind the outer ring, allowing a larger proportion of the power supplied to the heating element to be converted to generate heat and / or emit thermal radiation in the outer ring of the heating element where the greater heat losses occur, resulting in more uniform heating.

[0020] It should be noted that the at least two separate conductive electrode branches are recombined within the second section. Preferably, the at least two separate conductive electrode branches are confined within the second section.

[0021] In one embodiment, the conductive electrode comprises a carbon-based material, preferably a carbon-carbon composite (CCC) material, which allows for the use of heating elements in substrate processing systems for processing substrates at higher temperatures, for example, at temperatures in the range of 600-1300°C, more preferably at or around 1000°C, to grow two-dimensional graphene layers on the substrate.

[0022] In one embodiment, the heating element is a single-zone heating element that includes only one input contact and only one output contact. Such single-zone heating elements are relatively easy to produce and do not require complex controllers to individually control power to multiple zones, as in U.S. Patent Application Publication No. 2008 / 0029195, or multiple vertically stacked coils, as in U.S. Patent Application Publication No. 2021 / 0398829.

[0023] According to a second aspect, the present invention relates to a substrate processing system and an embodiment thereof, including the above-described first and second heating elements, wherein the first and second heating elements are disposed in a processing chamber, and the first and second heating elements are spaced apart to provide a processing compartment between the first and second heating elements. By providing a processing compartment between the two heating elements, it is possible to obtain a more uniform temperature distribution on the surface between the first and second heating elements, while there may be a temperature gradient in a direction perpendicular to the surface.

[0024] In one embodiment, the processing compartment includes a top wall and a bottom wall, and the first and second heating elements are disposed on the surfaces of the top wall and the bottom wall, respectively, outside the processing compartment. Thus, the first and second heating elements are disposed outside the processing compartment and are not affected or only to a small extent by substances used inside the processing compartment to process the substrate, such as gaseous substances for chemical vapor deposition and / or plasma. It should be noted that the first and second heating elements and the processing compartment are disposed within a processing chamber.

[0025] In one embodiment, the top and bottom walls of the processing compartment comprise plates of Shapal (AlN). Shapal, or aluminum nitride, is an electrical insulator material with high thermal conductivity that advantageously allows the heat generated by the heating element to be transferred to the inside of the processing compartment.

[0026] In one embodiment, the bottom wall of the processing compartment is configured to support the substrate to be processed, i.e., the upper wall of the lower one of the first and second heating elements is configured to support the substrate to be processed, so that gravity can assist in maintaining the substrate at a desired position within the processing compartment.

[0027] In one embodiment, the substrate processing system further includes a first heat shield and / or a second heat shield, where the first heat shield is positioned on a side of the first heating element facing away from the processing chamber at a distance from the first heating element, and the second heat shield is positioned on a side of the second heating element facing away from the processing chamber at a distance from the second heating element. In one embodiment, the first and / or second heat shields comprise one or more sheets of carbon-carbon composite (CCC), tungsten, molybdenum, and stainless steel. The first and / or second heat shields reduce heat loss on the side of the heating element facing away from the processing chamber and therefore contribute to more uniform heat generation by the heating element. In one embodiment, the substrate processing system includes a plurality of first heat shields and / or a plurality of second heat shields, where the plurality of heat shields are positioned back and forth at a distance from the heating element. Preferably, the plurality of heat shields includes four or five heat shields.

[0028] In one embodiment, the substrate processing system further includes a third and / or fourth heat shield, where the third heat shield is configured to provide a ring around the first heating element, the third heat shield being spaced apart from the first heating element, and the fourth heat shield is configured to provide a ring around the second heating element, the fourth heat shield being spaced apart from the second heating element. In one embodiment, the third and / or fourth heat shields comprise sheets of one or more of carbon-carbon composite (CCC), tungsten, molybdenum, and stainless steel. The third and / or fourth heat shields substantially reduce heat loss at the periphery of the heating element, thus contributing to more uniform heat generation by the heating element.

[0029] According to a third aspect, the present invention relates to a method or an embodiment thereof for processing a substrate in a substrate processing system as described above, comprising: The method is: providing a substrate and placing the substrate in a processing compartment; heating the substrate in the processing compartment using the first heating element and the second heating element; At least includes.

[0030] In one embodiment, the first and second heating elements are powered to generate heat and / or emit thermal radiation to heat the substrate and / or processing compartment to a temperature in the range of 600°C to 1300°C, particularly to a temperature at or around 1000°C.

[0031] The various aspects and features described and illustrated in this specification may, to the extent possible, be applied individually. These individual aspects, in particular those aspects and features described in the accompanying dependent claims, may be the subject of divisional patent applications.

[0032] The invention will be elucidated on the basis of exemplary embodiments shown in the accompanying drawings. [Brief explanation of the drawings]

[0033] [Figure 1A] 1 is a schematic diagram of a first example of a heating element according to the present invention; [Figure 1B] FIG. 2 is a schematic top view of an alternative to the first example of a heating element according to the present invention. [Figure 2] FIG. 2 is a top view of a second example of a heating element according to the present invention. [Figure 3] 1 is a partial cross-sectional view of a first example of a substrate processing system according to the present invention; [Figure 4] 4 shows a schematic diagram of a temperature profile in the substrate processing system of FIG. [Figure 5] FIG. 10 is a top view of a third example of a resistive heating element according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0034] 1A shows a schematic diagram of a first example of a heating element 100 according to the present invention. The heating element 100 in this example has a generally planar shape. It should be noted that the plane 130 on which the heating element 100 is disposed does not have to be a flat plane, but may be curved, for example so that the plane extends substantially parallel to the curved surface of the substrate.

[0035] The heating element 100 according to this example comprises the following components electrically coupled in series behind each other: an input contact 102; a first section 121 including a conductive electrode 103 including a first heat generating component 111; a second section 122, in which the conductive electrode is divided into at least two separate conductive electrode branches 141, 142 electrically connected in parallel, each conductive electrode including a second heat-generating element 112 and a third heat-generating element 113, respectively; a third section 123 including a conductive electrode 105 including a fourth heat generating component 114; Output contact 106 and Includes.

[0036] Note that the two separate conductive electrode branches 141 , 142 are reconnected within the second section 122 .

[0037] The first, second, third, and / or fourth heat-generating components 111, 112, 113, 114 in this example include emitters for emitting infrared or thermal radiation. Preferably, the amount of infrared or thermal radiation emitted is a function of the current passing through the emitter. Examples of emitters for infrared radiation include heat lamps, infrared lamps, or infrared light-emitting diodes (LEDs).

[0038] During use of the heating element 100, current flowing from the input contact 102 to the output contact 106 flows through the conductive electrode 103 in the first section 121, splits in the second section 122 where the current is distributed to at least two separate conductive electrode branches 141, 142 electrically connected in parallel, and recombines before reaching the third section 123 where the total current again flows through the conductive electrode 105. Thus, the first and fourth heat generating elements 111, 114 receive the total current through the heating element 100. The second and third heat generating elements 112, 113 receive a portion of the total current through the heating element 100 that depends on the electrical resistance of the separate conductive electrode branches 141, 142. In this example, there are two separate conductive electrode branches 141, 142, and when the electrical resistances of the two electrode branches 141, 142 are substantially equal, the total current through the heating element 100 is distributed so that the current through each of the two electrode branches 141, 142 is substantially half of the total current. Because the power generated by a heat-generating component is a function of the current through the heat-generating component, the power generated by the first and fourth heat-generating components 111, 114 is higher than the power generated by the second and third heat-generating components 112, 113, respectively. The relatively high power generation in the first section 121 and the third section 123 is used to compensate for heat losses at the edges 131, 132 of the plane 130.

[0039] Figure 1B shows a schematic diagram of a first alternative example of a heating element 100 according to the present invention. The heating element 100 in this example has substantially the same planar shape as the example in Figure 1A. In the alternative example of Figure 1B, the number of heat-generating elements along the edge of the heating element is equal to the number of heat-generating elements in the center of the heating element.

[0040] The heating element 100 according to this alternative example includes the following components electrically coupled in series behind one another: an input contact 102; a first section 121 including a conductive electrode 103 including a pair of first heat generating components 111a, 111b electrically connected in series; a second section 122, in which the conductive electrode is divided into at least two separate conductive electrode branches 141, 142 electrically connected in parallel, each conductive electrode including a second heat-generating element 112 and a third heat-generating element 113, respectively; a third section 123 including a conductive electrode 105 including a pair of fourth heat generating components 114a, 114b electrically connected in series; Output contact 106 and Includes.

[0041] Note that the two separate conductive electrode branches 141 , 142 are reconnected within the second section 122 .

[0042] Again, the first, second, third, and / or fourth heat-generating components 111a, 111b, 112, 113, 114a, 114b of this alternative embodiment include emitters for emitting infrared or thermal radiation, with the amount of emitted infrared or thermal radiation being a function of the current through the emitters. Thus, the heating elements 111a, 111b, 114a, and 114b receive a total current and therefore have a high output power. Because the central heating elements 112 and 113 are electrically connected in parallel, the total current is shared between these two heating elements, reducing the amount of heat they generate. The relatively high heat output in the first section 121 and the third section 123 is used to compensate for heat loss at the edges 131, 132 of the flat surface 130.

[0043] Figure 2 shows a schematic top view of a first example of a resistive heating element 1 according to the present invention. As shown in Figure 2, the resistive heating element 1 has a generally circular shape that is particularly suitable for use in substrate processing systems in which the substrate is a generally circular plate, such as a silicon wafer.

[0044] The resistive heating element 1 in this example comprises the following components connected in series behind each other: Input contact 2, A conductive electrode, a first section 3 providing part of the outer ring; a second section 4 disposed in an inner region of the outer ring, the second section 4 being divided into two separate conductive electrode branches 41, 42; a third section 5 that provides the remainder of the outer ring; a conductive electrode comprising: Output contact 6 and Includes.

[0045] Note that the two separate conductive electrode branches 41, 42 are recombined within the second section 5 before reaching the third section 5. Thus, in this example, the two separate conductive electrode branches are confined within the second section 4.

[0046] In this example, the third section 5 is substantially symmetrical to the first section 3 about the center point CP of the resistive heating element. In addition, the second section 4 is substantially completely divided into two separate conductive electrode branches 41, 42.

[0047] Although the thickness of the conductive electrodes may vary along the path of the conductive electrodes, in this example the resistive heating element 1 has a substantially constant thickness in a direction perpendicular to the plane of the drawing. In this example, the resistive heating element 1 is made from a carbon-carbon composite (CCC) having a thickness of about 3 mm. Slots 7 defining the paths of the conductive electrodes are cut out of a sheet of CCC material using, for example, a water jet cutter.

[0048] As shown schematically in FIG. 2, each of the two separate conductive electrode branches 41, 42 has a first serpentine path from the outer ring of the resistive heating element toward the center point CP in a first quarter of the circular area of ​​the resistive heating element, followed by a second serpentine path from the center of the resistive heating element toward the outer ring in a second quarter adjacent to the first quarter of the circular area of ​​the resistive heating element.

[0049] As shown in Figure 2, the turns in the serpentine path of the conductive electrode are provided with cuts 8. The cuts 8 at the turns in the serpentine path are configured to prevent cold spots in the temperature distribution across the resistive heating element.

[0050] In the example of Figure 2, one or more of the turning portions includes two notches 8 that extend at angles α1, α2, α3 relative to each other. The angles α1, α2, α3 are greater than 0 degrees and less than 180 degrees. In the example of Figure 2, the angle α1, α2, α3 between the two notches 8 in a turning portion is substantially 45 degrees, 90 degrees, or 135 degrees. In the example of Figure 2, substantially each turning portion includes two notches 8, except for the turning portion closest to the center point CP of the resistive heating element.

[0051] Furthermore, the width of the two separate conductive electrode branches 41, 42 in a direction parallel to the plane of the conductive electrode varies along the path. The longer the path to the center point CP of the resistive heating element, the wider the conductive electrode, and the less heat will be generated for a given current through the conductive electrode. This allows for fine tuning of the resistive heating to obtain optimal, uniform heat distribution for a particular application.

[0052] Figure 3 shows a schematic partial cross-sectional view of a first example of a substrate processing system 10 according to the present invention. The cross-sectional view of Figure 3 extends from a center point P to the periphery of the substrate processing system 10. The left side of the cross-sectional view is therefore equivalent to a mirror image at a line 20 passing through the center point CP.

[0053] The substrate processing system 10 includes a first heating element 11 and a second heating element 12. Each of the first and second heating elements 11, 12 preferably includes a resistive heating element 1 as shown in FIG. 2 . The substrate processing system 10 further includes a processing compartment 13 disposed between the first heating element 11 and the second heating element 12. The processing compartment 13 includes a top wall 14 and a bottom wall 15 made of a thermally conductive material, in this specific example, Shapal (AlN). The bottom wall 15 is configured to support a substrate to be processed, such as a silicon wafer. Additionally, the processing compartment 13 is configured to allow introduction of processing gases or vapors into the processing compartment 13. The substrate processing system 10 is disposed within a processing chamber (not shown).

[0054] As shown schematically in FIG. 3, the first heating element 11 is positioned against the side of the top wall 14 facing outward of the processing compartment 13, and the second heating element 12 is positioned against the side of the bottom wall 15 facing outward of the processing compartment 13.

[0055] The substrate processing system 10 further includes a first heat shield 16 disposed on a side of the first heating element 11 facing away from the processing compartment 13 at a distance from the first heating element 11. Additionally, the substrate processing system 10 includes a second heat shield 17 disposed on a side of the second heating element 12 facing away from the processing compartment 13 at a distance from the second heating element 12. In particular, the first heat shield 16 and the second heat shield 17 include two layers 16a, 16b, 17a, 17b of heat-reflective and / or insulating material. In this example, the first and / or second heat shield 16, 17 include layers 16a, 16b, 17a, 17b including one or more sheets of carbon-carbon composite (CCC), tungsten, molybdenum, and stainless steel.

[0056] The substrate processing system 10 further includes a third heat shield 18 that forms a ring around the first heating element 11 and is spaced apart from the first heating element 11. The third heat shield 18 is connected to the top wall 14 of the processing chamber 13 and extends in a direction perpendicular to the surface of the top wall 14. In the example of Figure 3, the first heat shield 16 is connected to the third heat shield 18 at a position spaced apart from the top wall 14 and the first heating element 11.

[0057] In addition, the substrate processing system 10 further includes a fourth heat shield 19 that forms a ring around the second heating element 12 and is spaced apart from the second heating element 12. The fourth heat shield 19 is connected to the bottom wall 15 of the processing chamber 13 and extends in a direction perpendicular to the surface of the bottom wall 15. In the example of Figure 3, the second heat shield 17 is connected to the fourth heat shield 19 at a position spaced apart from the bottom wall 15 and the second heating element 12. In this example, the third and fourth heat shields 18, 19 are made of stainless steel or molybdenum.

[0058] It should be noted that the third and fourth heat shields 18, 19 are connected to or are part of the processing chamber or housing of the substrate processing system 10, which is preferably provided with ducts for a cooling fluid, e.g., cooling water. In such a substrate processing system 10, this is a further reason for increased heat loss at the periphery of the first and second heating elements 11, 12. As explained in more detail above, this heat loss is compensated for by the outer rings 51, 52 of the first and second heating elements 11, 12. The outer rings 51, 52 have a width w0 through which, in use, all of the drive current flows. Between the outer rings 51, 52 and the center point CP, the conductive electrode path is divided into two separate conductive electrode branches electrically connected in parallel (see FIG. 2 ), so that, in use, only a portion of the total drive current flows through the conductive electrode branches. In the example of FIG. 2, the conductive electrode branches have substantially equal resistance, and therefore the total current is divided substantially in half as it flows through one of the conductive electrode branches.

[0059] 2 and 3, the width of each conductive electrode branch varies as a function of the distance to the center point CP. By selecting an appropriate set of widths w1, w2, w3, w4, w5, the temperatures of the first and second resistive heating elements 11, 12 can be optimized to provide a substantially uniform temperature distribution.

[0060] FIG. 4 schematically illustrates a simulation of a temperature profile in the substrate processing system of FIG. The treatment compartment 13 has a height of 10 mm, The top wall 14 and bottom wall 15 have a thickness of 3 mm and are made of Shapal, The first and second resistive heating elements 11, 12 have a thickness of 3 mm and a diameter of 110 mm, and the conductive electrode branches inside the outer rings 51, 52 include five coils with w1 = 7 mm, w2 = 9 mm, w3 = 19 mm, w4 = 20 mm, and w5 = 18 mm.

[0061] As shown schematically in Figure 4, the temperature variation of the heating elements 11, 12 is expected to be about 6 degrees around the operating temperature of about 1355 degrees, which is a variation of about 0.4%. Note that R (m) in the graph of Figure 4 is the distance from the center point CP.

[0062] Valleys in the temperature profile may even be reduced by varying the width w3. Additionally or alternatively, each of the conductive electrode branches may be further divided into two conductive electrode sub-branches electrically connected in parallel, whereby the current flowing through the conductive electrode branch in use is redistributed between the two conductive electrode sub-branches.

[0063] 5 is a top view of a second example of a resistive heating element 1′ according to the present invention, with some minor modifications. Most notably, compared to the first example of FIG. 2 , a first serpentine path from the outer ring 3′ of the resistive heating element to the center point CP spans more than a quarter of the circular area of ​​the resistive heating element 1′, followed by a second serpentine path from the center of the resistive heating element to the outer ring 3′ that spans less than a quarter of the circular area of ​​the resistive heating element 1′. Consequently, the radially arranged slots 7′ are no longer substantially perpendicular to one another, as in the first example of FIG. 2 , which allows tailoring the resistive heating element 1′ to the specific requirements and characteristics of the substrate processing system, such as the location within the substrate processing system where gases or vapors for processing a substrate are disposed and / or the location of openings for introducing or removing substrates from the processing compartment, and, of course, a more uniform temperature distribution across the area of ​​the resistive heating element.

[0064] In addition, some of the slits 8' are shaped differently to optimize the prevention of cold spots in the temperature distribution across the resistive heating element 1'.

[0065] It should be understood that the above description is included to illustrate the operation of the preferred embodiments and is not intended to limit the scope of the invention. Many variations will be apparent to those skilled in the art from the above discussion which would still fall within the scope of the invention.

[0066] In summary, the present invention relates to a heating element, a substrate processing system including such a heating element, and a method for processing substrates in such a substrate processing system. The heating element includes a conductive electrode extending along a path between an input contact and an output contact. The conductive electrode includes a segment along the path where the conductive electrode divides into at least two separate conductive electrode branches electrically connected in parallel. The conductive electrode and the at least two separate conductive branches include a heat-generating component configured to generate heat and / or emit thermal radiation when an electric current is passed through the heat-generating component.

Claims

1. 1. A heating element for a substrate processing system, comprising: the heating element includes a conductive electrode, the conductive electrode extending along a path between an input contact and an output contact; the conductive electrode includes a segment along a path that divides the conductive electrode into at least two separate conductive electrode branches electrically connected in parallel; the conductive electrode and the at least two separate conductive branches each include a heat-generating component configured to generate heat and / or emit thermal radiation when an electrical current is passed through the heat-generating component; Heating element.

2. 2. The heating element of claim 1, wherein the heat generating component extends along the conductive electrode, preferably over substantially the entire length of the conductive electrode.

3. The heating element of claim 1 or 2, wherein the heat generating component comprises an electrical resistance heat generating component.

4. 4. The heating element of claim 3, wherein the electrical resistance heating component has a cross-sectional area in a direction substantially transverse to a direction along the path from the input contact to the output contact, the cross-sectional area varying along the path.

5. 5. The heating element of claim 4, wherein the path is disposed in a plane, the thickness of the electrical resistance heating component in a direction perpendicular to the plane is substantially constant, and the width of the electrical resistance heating component in a direction parallel to the plane varies along the path.

6. 6. The heating element of claim 1, wherein the heating element includes an edge, the conductive electrode includes a first section adjacent the edge and a second section, the first section and the second section being electrically connected in series, the first section being disposed between the edge and the second section, and the second section of the conductive electrode includes the segment along the path along which the conductive electrode is divided into the at least two separate conductive electrode branches that are electrically connected in parallel.

7. 7. The heating element of claim 6, wherein the first section provides an outer ring that substantially surrounds the second section of the heating element, or wherein the conductive electrode comprises two first and second sections electrically connected in series, the second section being disposed between the two first sections, and each of the two first sections providing a portion of the outer ring that substantially surrounds the second section of the heating element.

8. 8. A heating element according to claim 6 or 7, wherein the second section is substantially completely divided into the at least two separate conductive electrode branches which are electrically connected in parallel.

9. A heating element according to any one of the preceding claims, wherein the conductive electrodes comprise a carbon-based material, preferably a carbon-carbon composite (CCC) material.

10. A heating element according to any one of claims 1 to 9, wherein the heating element is a single-zone heating element comprising only one input contact and only one output contact.

11. A substrate processing system including a first heating element and a second heating element according to any one of claims 1 to 10, wherein the first heating element and the second heating element are disposed within the processing chamber, and the first heating element and the second heating element are disposed at a distance from each other to position a processing compartment between the first heating element and the second heating element.

12. 12. The substrate processing system of claim 11, wherein the processing compartment comprises a top wall and a bottom wall, the first heating element and the second heating element are disposed against a surface of the top wall and a surface of the bottom wall outside the processing compartment, respectively, and preferably the top wall and the bottom wall comprise plates of Shapal (AlN).

13. The substrate processing system of claim 12 , wherein the bottom wall of the processing compartment is configured to support a substrate to be processed.

14. the substrate processing system further includes a first thermal shield and / or a second thermal shield; the first heat shield is positioned spaced apart from the first heating element on a side of the first heating element facing away from the processing compartment; the second heat shield is positioned spaced apart from the second heating element on a side of the second heating element facing away from the processing compartment; 14. A substrate processing system according to any one of claims 11 to 13, wherein the first and / or second heat shields preferably comprise sheets of one or more of carbon-carbon composite (CCC), tungsten, molybdenum, stainless steel.

15. the substrate processing system further includes a third thermal shield and / or a fourth thermal shield; the third heat shield is configured to provide a ring around the first heating element, the third heat shield being spaced apart from the first heating element; the fourth heat shield is configured to provide a ring around the second heating element, the fourth heat shield being spaced apart from the second heating element; 15. A substrate processing system according to any one of claims 11 to 14, wherein the third and / or fourth heat shields preferably comprise sheets of one or more of carbon-carbon composite (CCC), tungsten, molybdenum, stainless steel.

16. 16. A method for processing a substrate in a substrate processing system according to any one of claims 11 to 15, the method comprising the steps of: providing the substrate and placing the substrate in the processing compartment; and heating the substrate in the processing compartment using the first heating element and the second heating element.

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