High heat capacity hot plate

Abstract

According to one embodiment, an apparatus for a hotplate device is disclosed. The hotplate device includes a housing structure, an alloy, and a heating element. The housing structure includes an outer shell surrounding a cavity. The alloy is disposed within the cavity. The alloy has a melting temperature range. The heating element is configured to transition the alloy from a solid state to a liquid state at a set temperature within the melting temperature range.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Non-Provisional Patent Application No. 17 / 989,333, filed November 17, 2022, which is incorporated herein by reference in its entirety.

[0002] FIELD OF THE DISCLOSURE The present disclosure relates generally to semiconductor manufacturing and, in particular embodiments, to hot plates used in, for example, semiconductor manufacturing. [Background technology]

[0003] Semiconductor manufacturing consists of several process steps that create a finished chip or integrated circuit. These steps include creating a wafer, adding one or more films, depositing photoresist, exposing the wafer to a pattern of actinic radiation, developing the soluble portions of the photoresist, etching the wafer, and cleaning the wafer. This process can be performed several times until the desired structures are added and unwanted material is removed. The corresponding circuit can then be tested.

[0004] Typically, there are several bake steps in semiconductor manufacturing. For example, bake steps associated with photolithography processes include bake, pre-bake, post-exposure bake, and post-bake. These bake steps are commonly used in conjunction with the deposition and setting of films such as photoresist, and benefit from precise temperature control.

[0005] For example, when baking a wafer, the wafer chuck is heated to within 0.1 degrees using a hotplate so that the wafer is heated uniformly across its entire surface area. Typically, the hotplate is set to the desired temperature, and then the cold wafer is introduced into the system. The system temperature drops upon loading (i.e., introduction) of the cooled wafer. The process requires a period of time for the system temperature to reach the desired value. It would be advantageous to have a hotplate that can reliably maintain the desired temperature when loading the cold wafer. Summary of the Invention [Means for solving the problem]

[0006] Technical advantages are generally achieved by embodiments of the present disclosure, which describe hotplates used, for example, in semiconductor manufacturing, that have high heat capacity.

[0007] A first aspect relates to a hotplate apparatus. The hotplate apparatus includes a housing structure, an alloy, and a heating element. The housing structure includes an outer shell surrounding a cavity. The alloy is disposed within the cavity. The alloy has a melting temperature range. The heating element is configured to transition the alloy from a solid state to a liquid state at a set temperature within the melting temperature range.

[0008] Thus, in a first implementation of the hotplate device according to the first aspect, the alloy comprises bismuth (Bi), lead (Pb), tin (Sn), cadmium (Cd), or a combination thereof.

[0009] Thus, in the second implementation of the hot plate device according to the first aspect or any preceding implementation of the first aspect, the alloy consists of 42.5-50% bismuth, 25-37.7% lead, 11.3-25% tin, and 0-8.5% cadmium.

[0010] Thus, in the third implementation of the hotplate device according to the first aspect or any preceding implementation of the first aspect, the alloy consists of 42.5% bismuth, 37.7% lead, 11.3% tin, and 8.5% cadmium.

[0011] Thus, in the fourth implementation of the hotplate device according to the first aspect or any preceding implementation of the first aspect, the alloy consists of 50% bismuth, 25% lead, and 25% tin.

[0012] Thus, in the fifth implementation of the hotplate apparatus according to the first aspect or any preceding implementation of the first aspect, the alloy is in a solid state at room temperature.

[0013] Thus, in the sixth implementation of the hot plate apparatus according to the first aspect or any preceding implementation of the first aspect, the outer shell is made of aluminum.

[0014] Thus, in the seventh implementation of the hot plate apparatus according to the first aspect or any preceding implementation of the first aspect, the thickness of the outer shell is 3 millimeters (mm) or less.

[0015] Thus, in the eighth implementation of the hot plate apparatus according to the first aspect or any preceding implementation of the first aspect, the top surface of the housing structure is configured to hold a wafer.

[0016] Thus, in the ninth implementation of the hotplate apparatus according to the first aspect or any preceding implementation of the first aspect, the outer shell encloses the cavity.

[0017] Thus, in a tenth implementation of the hot plate apparatus according to the first aspect or any preceding implementation of the first aspect, the hot plate apparatus is configured to heat the wafer to a melting temperature range of the alloy during a post-exposure bake (PEB).

[0018] A second aspect relates to a hotplate apparatus. The hotplate apparatus includes a housing structure and a heating element. The housing structure includes an outer shell enclosing a first cavity and a second cavity. The first cavity is filled with a first alloy having a first melting range. The second cavity is filled with a second alloy having a second melting range. The heating element is configured to bring the first alloy to a first temperature within the first melting range during a first operating mode of the hotplate apparatus. The heating element is configured to bring the second alloy to a second temperature within the second melting range during a second operating mode of the hotplate apparatus. The second temperature is higher than the first temperature.

[0019] Thus, in a first implementation of the hot plate device according to the second aspect, the first cavity includes a plurality of first channels, and in this embodiment, the first alloy spreads uniformly through the plurality of first channels at the first temperature.

[0020] Thus, in the second implementation of the hot plate device according to the second aspect or any preceding implementation of the second aspect, each of the plurality of first channels is coupled to one another via a first connecting channel.

[0021] Thus, in the third implementation of the hot plate device according to the second aspect or any preceding implementation of the second aspect, the second cavity includes a plurality of second channels, and the second alloy spreads uniformly through the plurality of second channels at the second temperature.

[0022] Thus, in the fourth implementation of the hot plate device according to the second aspect or any preceding implementation of the second aspect, each of the plurality of second channels is coupled to one another via a second connecting channel.

[0023] Thus, in the fifth implementation of the hot plate device according to the second aspect or any preceding implementation of the second aspect, the first channels and the second channels are arranged parallel to each other, and each first channel is arranged adjacent to a neighboring second channel.

[0024] A third aspect relates to a method for operating a hotplate in a first mode and a second mode of operation. The hotplate includes a housing structure having a heating element, an outer shell enclosing a first cavity and a second cavity, a first alloy disposed in the first cavity and having a first melting temperature range, and a second alloy disposed in the second cavity and having a second melting temperature range. In the first mode of operation, the method includes causing the heating element to transition the first alloy to a first temperature within the first melting temperature range, and in the second mode of operation, the method includes causing the heating element to transition the second alloy to a second temperature within the second melting temperature range.

[0025] Thus, in a first implementation of the method according to the third aspect, the first alloy and the second alloy each include bismuth (Bi), lead (Pb), tin (Sn), cadmium (Cd), or a combination thereof.

[0026] Thus, in the second implementation of the method according to the third aspect or any preceding implementation of the third aspect, the first alloy and the second alloy are in a solid state at room temperature.

[0027] The embodiments may be implemented in hardware, software, or any combination thereof.

[0028] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a block diagram of a hot plate according to an embodiment. [Figure 2] FIG. 1 is a cross-sectional plan view of one embodiment of a housing structure having multiple cavities. [Figure 3]1 is a cross-sectional plan view of a housing structure in one embodiment having a first set of horizontal cavities mated with a first vertical cavity and a second set of horizontal cavities mated with a second vertical cavity. FIG. [Figure 4] FIG. 1 is a flow diagram of one embodiment method of operation of a hot plate. DETAILED DESCRIPTION OF THE INVENTION

[0030] The present disclosure provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. Specific embodiments are merely illustrative of particular configurations and do not limit the scope of the claimed embodiments. Features from different embodiments may be combined to form further embodiments, unless otherwise specified.

[0031] Variations or modifications described with respect to one of the embodiments may also be applied to the other embodiments. Furthermore, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the present disclosure as defined by the appended claims.

[0032] Although aspects of the present invention are described primarily in the context of hot plates used in semiconductor manufacturing, aspects of the present invention may be applicable to areas outside the semiconductor industry as well. For example, hot plates can be used for cooking, as a heat source in laboratories, etc. In these various embodiments, and throughout the industry, a hot plate that can reliably maintain a desired temperature through the introduction of external devices onto the hot plate, as disclosed herein, would be advantageous.

[0033] In one embodiment, a hotplate is provided that includes a cavity within a housing structure. A non-eutectic alloy having a melting temperature range is disposed within the cavity. A heating element of the hotplate transitions the non-eutectic alloy from a solid state to a liquid state at a set temperature within the alloy's melting temperature range. The non-eutectic alloy begins to melt at a first melting temperature but does not change to a liquid state (e.g., between the solid and liquid states) until a second melting temperature higher than the first melting temperature is reached. When the non-eutectic alloy is at a temperature within the melting temperature range, the specific heat capacity of the mixture is significantly greater than the specific heat capacity of the mixture in either the solid or liquid state.

[0034] Embodiments of the present disclosure take advantage of this increased heat capacity by setting the hotplate to a temperature within the melting temperature range of the mixture. In this configuration, external objects with different temperatures have minimal effect on the surface temperature when placed on the hotplate surface.

[0035] Aspects of the present disclosure provide hotplates having multiple cavities, with different cavities containing different non-eutectic mixtures. In such embodiments, the hotplate can take advantage of the increased heat capacity of each non-eutectic mixture at their corresponding melting temperature ranges. These and further details are discussed in more detail below.

[0036] FIG. 1 illustrates an embodiment of a hotplate 100. The hotplate 100 includes a housing structure 102, a top surface 108, and heating elements 110, which may (or may not) be arranged as shown. In an embodiment, the hotplate is configured to heat a wafer 112 during a post-exposure bake (PEB). Additionally, the hotplate 100 may include additional components not depicted in FIG. 1.

[0037] The housing structure 102 includes an outer shell 104 that surrounds a cavity 106. In an embodiment, the outer shell 104 encloses the cavity 106. In an embodiment, the cavity 106 is an open volume within the housing structure 102 that is completely surrounded by the outer shell 104 that holds an alloy, preferably a non-eutectic mixture. In an embodiment, the outer shell is made of aluminum. In an embodiment, the outer shell 104 is a thin metal clad having a thickness of 3 millimeters (mm) or less. In general, it is preferred that the thickness of the metal clad be as thin as possible to increase heat capacity while maintaining structural rigidity.

[0038] The heating element 110 is thermally coupled to the housing structure 102. The heating element 110 radiates heat through the housing structure 102 toward the top surface 108 of the hotplate 100. The housing structure 102 distributes the heat evenly across the top surface 108 of the hotplate 100.

[0039] In an embodiment, the heating element 110 has a serpentine shape housed within a separate housing.

[0040] In an embodiment, the heating element 110 is electrically coupled to a temperature sensor 116 and a controller 114. The temperature sensor 116 is mounted, for example, to the housing structure 102 or the top surface 108 of the hotplate. The controller 114 monitors the temperature at the mounted surface, for example, and sets the heating element to a corresponding desired temperature. In an embodiment, a feedback circuit in the controller 114 may be used to maintain the desired temperature.

[0041] The top surface 108 is used as a location for an object to be heated to a set temperature. In an embodiment, the top surface 108 is configured to hold a wafer for semiconductor processing. The shape of the top surface 108 is non-limiting, and any shape of the top surface 108 is contemplated.

[0042] In an embodiment, the alloy within cavity 106 is a non-eutectic mixture having a melting point range between a first melting point and a second melting point. At temperatures below the first melting point (i.e., solidus temperature), the non-eutectic alloy is solid (e.g., not molten). At temperatures above the second melting point (i.e., liquidus temperature), the non-eutectic alloy is liquid (e.g., molten). Because the alloy is a non-eutectic alloy, the first melting point is different from the second melting point.

[0043] Generally, between the first and second melting points (i.e., the melting temperature range), some of the non-eutectic mixture will melt, while others will not. At any point within the melting temperature range, the atoms of the non-eutectic mixture are neither tightly packed as in the solid state nor flow freely and separately as in the liquid state. In this intermediate state, in addition to kinetic energy, there is additional potential energy that results from the atoms being pulled apart or crushed (similar to a spring). As a result, in this conditional state, the specific heat capacity of the non-eutectic mixture tends to be much higher compared to the specific heat capacity of the non-eutectic mixture in either the solid or liquid state.

[0044] Embodiments of the present disclosure advantageously take advantage of the higher specific heat capacity of non-eutectic mixtures operating within the melting temperature range.

[0045] In some embodiments, the alloy is a eutectic mixture having a single melting point value. In contrast to non-eutectic mixtures, in eutectic mixtures, the first melting point (i.e., solidus temperature) is the same as the second melting point (i.e., liquidus temperature). In such embodiments, the benefits of the corresponding hotplate are limited to a single temperature (i.e., melting temperature), which has less practical use cases than hotplates having non-eutectic mixtures with a range of melting temperatures.

[0046] Like non-eutectic mixtures, eutectic mixtures have a much higher specific heat capacity at the melting point compared to the specific heat capacity in the solid or liquid state. However, unlike non-eutectic mixtures, which have a range of melting points, eutectic mixtures have a single melting point value. Therefore, the benefits provided by this property are more limited in the case of eutectic mixtures.

[0047] In various embodiments, the cavity 106 of the hotplate 100 contains a non-eutectic mixture. In response to setting the temperature of the hotplate to a temperature corresponding to a temperature within the melting temperature range of the non-eutectic mixture, a portion of the non-eutectic mixture within the cavity 106 melts, while other portions of the non-eutectic mixture within the cavity 106 do not melt. The non-eutectic mixture is thermally coupled to the outer shell 104 of the housing structure 102, which is in turn thermally coupled to the top surface 108 of the hotplate 100. In this configuration, while the non-eutectic mixture is at a temperature within the melting temperature range, the specific heat capacity of the system (i.e., the hotplate apparatus) is significantly higher than the specific heat capacity of the system when the temperature is set to a value at which the non-eutectic mixture is still in a solid state or at which the non-eutectic mixture is in a liquid state.

[0048] Furthermore, the specific heat capacity of the system in this configuration is orders of magnitude greater than the specific heat capacity of a hotplate having a solid (ie, cavity-free) housing structure.

[0049] For example, a typical solid aluminum hotplate with a specific heat capacity of 3,492 J / kg°C when constructed with a housing structure having a cavity constructed from a non-eutectic mixture as disclosed herein (e.g., a mixture of bismuth (Bi), lead (Pb), tin (Sn), and cadmium (Cd), or a combination thereof) has a specific heat capacity of 29,250 J / kg°C.

[0050] Due to the increased specific heat capacity of hot plate 100, when the temperature is set to a point within the melting temperature range of the non-eutectic mixture, placing an object on top surface 108 having a temperature significantly different from the set temperature of hot plate 100 does not result in a significant decrease in temperature at top surface 108 compared to conventional hot plates.

[0051] For example, when a cold (i.e., 23° C.) 300 mm diameter and 875 μm thick silicon wafer (or any other similar material) is placed on a typical solid aluminum hotplate set at 80° C., the temperature drop is approximately 2.9° C. In comparison, when the same cold wafer is placed on a hotplate 100 having approximately the same dimensions and a non-eutectic mixture of bismuth, lead, tin, and cadmium, or a combination thereof, set at the same 80° C., the temperature drop is approximately 0.5° C.

[0052] Thus, advantageously, the increased specific heat capacity of the non-eutectic mixture within cavity 106 allows, for example, the introduction of a cold wafer during wafer bake while maintaining a desired temperature at top surface 108. Embodiments of the present disclosure therefore minimize any undesirable increase in the time required to bring the temperature of the hotplate and cold wafer back to the desired temperature after the introduction of the cold wafer.

[0053] Advantageously, by selecting a non-eutectic mixture based on its corresponding melting temperature range and the desired bake temperature of the wafer, the hotplate can substantially maintain a set temperature upon introduction of a cold wafer.

[0054] It should be noted that while hotplate 100 can greatly benefit from a non-eutectic alloy having a melting temperature range within cavity 106, a temperature range over which hotplate 100 can operate, a hotplate having a eutectic alloy within cavity 106 is also contemplated. However, unlike a non-eutectic alloy, the benefits of a hotplate having a eutectic alloy within cavity 106 are limited to a single temperature (i.e., the melting point of the eutectic alloy).

[0055] In embodiments, the alloy is a mixture of one or more of bismuth, lead, tin, and cadmium. Note that non-eutectic mixtures are not limited to such alloys, but rather any non-eutectic mixture with a melting temperature range is contemplated (as opposed to a eutectic mixture with a single melting temperature point).

[0056] In one embodiment, the alloy consists of 42.5-50% bismuth, 25-37.7% lead, 11.3-25% tin, and 0-8.5% cadmium.

[0057] In one embodiment, the alloy is Cerrosafe® (also known as Wood's metal, Bend alloy, or pewtalloy), which is a non-eutectic mixture of 42.5% bismuth, 37.7% lead, 11.3% tin, and 8.5% cadmium. Cerrosafe® has a melting point between 158°F (70°C) and 190°F (88°C).

[0058] In another embodiment, the alloy is a non-eutectic mixture of 50% bismuth, 25% lead, and 25% tin. In this embodiment, the alloy has a melting point between 199°F (93°C) and 239°F (115°C).

[0059] In embodiments, the ratios of the mixture of bismuth, lead, tin, and cadmium are adjusted to achieve the desired temperature range based on the application.

[0060] In an embodiment, the alloy is in a solid state at room temperature.

[0061] 2 illustrates a cross-sectional plan view of one embodiment of a housing structure 102 having multiple cavities 202a-n. As shown, the cavities 202a-n are evenly distributed throughout the housing structure 102. In an embodiment, each cavity 202a-n is sealed.

[0062] In an embodiment, each cavity 202a-n contains one or more alloys, either eutectic or non-eutectic. For example, in one embodiment, each cavity 202a-n may contain the same non-eutectic alloy.

[0063] As another example, in one embodiment, each of the other cavities 202a-n may contain a different non-eutectic mixture. For example, the first cavity 202a may contain a first non-eutectic mixture, the second cavity 202b may contain a second non-eutectic mixture, and so on, with a repeating arrangement throughout the remaining cavities. In such an example, the hotplate 100 may advantageously have two different melting temperature ranges, one corresponding to the melting temperature range of the first non-eutectic mixture and a second corresponding to the melting temperature range of the second non-eutectic mixture.

[0064] It should be appreciated that other configurations involving additional placement of non-eutectic mixtures may be contemplated as well. Generally, the placement configuration may benefit from a uniform distribution of variation across the cavities 202a-n, but this is not limiting and other configurations are contemplated as well.

[0065] FIG. 3 shows another cross-sectional plan view of one embodiment of a housing structure 102 having a first set of horizontal cavities 308 paired with vertical cavities 306 and a second set of horizontal cavities 304 paired with vertical cavities 302.

[0066] Cavities 306 and 308 are sealed, allowing, for example, molten alloy within these cavities to flow freely therethrough. Similarly, cavities 302 and 304 are sealed, allowing, for example, molten alloy within these cavities to flow freely therethrough.

[0067] In one embodiment, cavities 302, 304, 306, and 308 have the same non-eutectic mixture, allowing hotplate 100 to advantageously operate over the melting temperature range of the non-eutectic mixture, as disclosed herein.

[0068] In another embodiment, cavities 302 and 304 contain a first non-eutectic mixture and cavities 306 and 308 contain a second non-eutectic mixture. In this embodiment, hotplate 100 can advantageously operate over two different melting temperature ranges for each of the non-eutectic mixtures, as disclosed herein.

[0069] For example, in one embodiment, cavities 302 and 304 contain a non-eutectic mixture of 42.5% bismuth, 37.7% lead, 11.3% tin, and 8.5% cadmium, while cavities 306 and 308 contain a non-eutectic mixture of 50% bismuth, 25% lead, and 25% tin. In such an embodiment, the hotplate can advantageously operate in a temperature range between 158°F (70°C) and 239°F (115°C). This contrasts with a hotplate having only a non-eutectic mixture of 42.5% bismuth, 37.7% lead, 11.3% tin, and 8.5% cadmium, which operates in a melting temperature range between 158°F (70°C) and 190°F (88°C). Similarly, this contrasts with hotplates that have only a non-eutectic mixture of 50% bismuth, 25% lead, and 25% tin, which operate at a melting temperature between 199°F (93°C) and 239°F (115°C).

[0070] As previously mentioned, a uniform distribution of cavities is beneficial but not limiting, and additional cavity arrangements may be considered as well to allow for a more uniform distribution and multiple melting temperature ranges for different non-eutectic mixtures.

[0071] Additionally, in each of Figures 2 and 3, multiple cavities may be arranged vertically (i.e., a sealed cavity on one plane and another sealed cavity on another plane between the first sealed cavity and the top surface 108) to provide the advantage of multiple non-eutectic mixtures within the hotplate 100.

[0072] 4 shows a flow diagram 400 of one embodiment of a method of operation of the hotplate 100. In step 402, a foreign object is placed on the hotplate 100. The temperature of the hotplate 100 is set so that the temperature of the non-eutectic mixture is within the melting temperature range. The introduction of the foreign object causes a temporary drop in the temperature of the hotplate 100.

[0073] In embodiments, optionally, a feedback circuit is used to adjust the heating element to slightly increase the set temperature to account for the minimal amount of temperature drop that results from the introduction of an external object.

[0074] In step 404, which is also applicable when the hotplate 100 contains a single non-eutectic mixture, the hotplate is set to a first temperature within the melting temperature range of the single or first non-eutectic mixture corresponding to a first mode of operation.

[0075] In step 406, the hotplate is set to a second temperature within the melting temperature range of the second non-eutectic mixture, corresponding to a second mode of operation. Additional modes of operation are contemplated as well.

[0076] 4 is not absolutely required, and in principle, various steps may be performed out of the order shown. Also, certain steps may be skipped, different steps may be added or substituted, or selected steps or groups of steps may be performed in different applications.

[0077] Although embodiments of the present disclosure have been discussed in the example of eutectic systems outside the eutectic point, embodiments of the present application may also be applied to solid solutions having a miscibility gap, eutectic systems outside the eutectic point, or peritectic / peritectic systems outside the peritectic / peritectic point.

[0078] Although described in detail, it should be understood that various changes, substitutions, and alterations may be made therein without departing from the spirit and scope of the present disclosure, as defined by the appended claims. Like elements in the various figures are designated with like reference numerals. Moreover, the scope of the present disclosure is not intended to be limited to the particular embodiments described herein; those skilled in the art will readily recognize from this disclosure that any now-existing or later-developed process, machine, manufacture, composition of matter, means, method, or step may perform substantially the same function or achieve substantially the same result as the corresponding embodiment described herein. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

[0079] The specification and drawings are therefore to be considered merely as illustrative of the disclosure as defined by the appended claims, and are intended to cover any and all modifications, variations, combinations, or equivalents that fall within the scope of the disclosure.

Claims

1. A hot plate apparatus comprising: a housing structure having an outer shell enclosing a cavity; an alloy disposed in the cavity, the alloy having a melting temperature range; a heating element configured to transition the alloy from a solid state to a liquid state at a set temperature within the melting temperature range. Hot plate equipment.

2. 10. The hot plate apparatus of claim 1, wherein the alloy comprises bismuth (Bi), lead (Pb), tin (Sn), cadmium (Cd), or a combination thereof.

3. 3. The hot plate apparatus of claim 2, wherein the alloy consists of 42.5-50% bismuth, 25-37.7% lead, 11.3-25% tin, and 0-8.5% cadmium.

4. 10. The hot plate apparatus of claim 1, wherein the alloy consists of 42.5% bismuth, 37.7% lead, 11.3% tin, and 8.5% cadmium.

5. 10. The hot plate apparatus of claim 1, wherein the alloy comprises 50% bismuth, 25% lead, and 25% tin.

6. 10. The hotplate apparatus of claim 1, wherein said alloy is in said solid state at room temperature.

7. 10. The hot plate apparatus of claim 1, wherein the outer shell is made of aluminum.

8. 10. The hot plate apparatus of claim 1, wherein the outer shell has a thickness of 3 millimeters (mm) or less.

9. The hot plate apparatus of claim 1 , wherein a top surface of the housing structure is configured to hold a wafer.

10. 10. The hot plate apparatus of claim 1, wherein the outer shell encloses the cavity.

11. 10. The hotplate apparatus of claim 1, wherein the hotplate apparatus is configured to heat a wafer to the melting temperature range of the alloy during a post-exposure bake (PEB).

12. A hot plate apparatus comprising: a housing structure having an outer shell enclosing a first cavity and a second cavity, the first cavity being filled with a first alloy having a first melting range and the second cavity being filled with a second alloy having a second melting range; a heating element configured to bring the first alloy to a first temperature within the first melting range during a first mode of operation of the hotplate apparatus and to bring the second alloy to a second temperature within the second melting range during a second mode of operation of the hotplate apparatus, the second temperature being higher than the first temperature. Hot plate equipment.

13. 13. The hot plate apparatus of claim 12, wherein the first cavity comprises a plurality of first channels, and the first alloy spreads uniformly throughout the plurality of first channels at the first temperature.

14. The hot plate apparatus of claim 13 , wherein each of the plurality of first channels is coupled to one another via a first connecting channel.

15. 14. The hot plate apparatus of claim 13, wherein the second cavity comprises a plurality of second channels, and the second alloy spreads uniformly through the plurality of second channels at the second temperature.

16. 16. The hot plate apparatus of claim 15, wherein each of the plurality of second channels is coupled to one another via a second connecting channel.

17. 16. The hot plate apparatus of claim 15, wherein the first channels and the second channels are disposed parallel to one another, and each first channel is disposed adjacent to an adjacent second channel.

18. 1. A method comprising: a hot plate including a heating element, a housing structure having an outer shell enclosing a first cavity and a second cavity, a first alloy disposed in the first cavity and having a first melting temperature range, and a second alloy disposed in the second cavity and having a second melting temperature range; In the first mode of operation, the method includes causing the heating element to transition the first alloy to a first temperature within the first melting temperature range; In the second mode of operation, the method includes causing the heating element to transition the second alloy to a second temperature within the second melting temperature range. method.

19. 20. The method of claim 18, wherein the first alloy and the second alloy each comprise bismuth (Bi), lead (Pb), tin (Sn), cadmium (Cd), or a combination thereof.

20. 20. The method of claim 18, wherein the first alloy and the second alloy are in a solid state at room temperature.

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