Wafer baking device

Abstract

The invention provides a wafer baking device, which comprises a hot cavity provided with a heating top plate and filled with a liquid heat transfer medium; the heating unit is used for heating the liquid heat transfer medium, boiling the liquid heat transfer medium and transferring heat to the heating top plate through hot steam generated by boiling of the liquid heat transfer medium; and the pressure control unit is configured to regulate and control the pressure intensity in the hot cavity to be maintained at the preset pressure intensity, so that when the liquid heat transfer medium is heated, the liquid heat transfer medium boils at the preset boiling point corresponding to the preset pressure intensity. According to the wafer baking device, the relationship between the boiling point of the liquid and the external pressure is utilized, and the pressure in the hot cavity is regulated and controlled through the pressure control unit, so that when the liquid heat transfer medium is heated, the liquid heat transfer medium boils at the preset boiling point corresponding to the preset pressure, and hot steam generated by boiling of the liquid heat transfer medium is in contact with and heats the disc surface of the top plate to achieve the purpose of heat conduction; and better heating temperature uniformity is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor manufacturing, and in particular relates to a wafer baking device. Background Art

[0002] Photolithography is a crucial process in semiconductor manufacturing. It utilizes photochemical reactions to transfer the pattern from the mask to the wafer, enabling selective etching and ion implantation. The basic photolithography process consists of wafer surface pretreatment, resist coating, pre-exposure bake (referred to as "soft bake"), exposure, post-exposure bake (referred to as "post bake"), development, and post-development bake (referred to as "hard bake"). The soft bake removes solvent from the photoresist, thereby improving its viscosity and uniformity, and controlling line width uniformity during etching. For chemically amplified photoresists, the soft bake can also be used to modify the diffusion length of the photoacid to adjust process window parameters. Typical soft bake temperatures range from 90°C to 100°C. The post bake heats the photochemical reaction to complete its full potential. In particular, for chemically amplified photoresists, the post bake generates additional acid, amplifying the photochemical reaction and significantly impacting photoresist performance. Post-bake temperature is one of the main factors affecting line width uniformity (CDU, CD uniformity). Typical post-bake temperatures range from 80°C to 200°C. Hardening bake is used to remove excess moisture absorbed by the photoresist after development, facilitating subsequent etching processes.

[0003] All baking processes are performed on a hot plate within the photoresist developer. The general process for wafer baking is as follows: After photoresist is coated, the wafer is robotically transferred to the hot plate directly above it, where it is baked. During the baking process, the temperature uniformity of the hot plate directly impacts the uniformity of the line width (CDU) after exposure. Therefore, temperature uniformity on the hot plate surface is a crucial technical specification for any photolithography process. Currently, traditional hot plates used for wafer baking utilize resistance wires to heat the plate surface. These resistance wires are divided into several control zones, and temperature regulation across these zones is used to achieve consistent temperature across the plate surface. However, in practice, the zoned arrangement of the resistance wires makes it difficult to achieve uniform temperature control across these zones. Furthermore, the accuracy of temperature control is relatively low, which can easily lead to process issues and affect wafer yield. Summary of the Invention

[0004] In order to improve the uniformity of heating of wafers by a hot plate during wafer baking, the present invention provides a wafer baking device.

[0005] The present invention provides a wafer baking device, comprising:

[0006] A heat cavity having a heating top plate and filled with a liquid heat transfer medium;

[0007] a heating unit for heating the liquid heat transfer medium and boiling the liquid heat transfer medium, and transferring heat to the heating top plate through hot vapor generated by the boiling of the liquid heat transfer medium;

[0008] The pressure control unit is configured to regulate the pressure in the heat chamber to maintain it at a preset pressure, so that when the liquid heat transfer medium is heated, it boils at a preset boiling point corresponding to the preset pressure.

[0009] According to a specific implementation of the embodiment of the present application, the pressure control unit includes a gas output port, a first gas delivery pipeline, a first valve, a pressure sensor and a controller;

[0010] The gas outlet is provided on the heat cavity and is located above the liquid level of the liquid heat transfer medium. The gas outlet is connected to the first gas delivery pipeline, and the first valve is provided on the first gas delivery pipeline.

[0011] The pressure sensor is arranged above the liquid heat transfer medium, and is used to monitor the pressure inside the heat cavity in real time and send the pressure detection value to the controller;

[0012] The controller is configured to receive the pressure detection value and control the opening or closing of the first valve according to the pressure detection value when the liquid heat transfer medium is heated, so as to maintain the pressure in the heat chamber at the preset pressure.

[0013] According to a specific implementation of the embodiment of the present application, the pressure control unit further includes a gas input port, a second gas delivery pipeline, and a second valve. The gas input port is provided on the heat cavity and is located above the liquid level of the liquid heat transfer medium. The gas input port is connected to the second gas delivery pipeline, and the second valve is provided on the second gas delivery pipeline.

[0014] The controller is further configured to control the opening or closing of the second valve.

[0015] According to a specific implementation of the embodiment of the present application, the heating top plate includes a process area and a transition area;

[0016] The process area is located in the middle area of ​​the heating top plate, and the size of the process area is greater than or equal to the size of the wafer to be heated;

[0017] The transition area is located at the edge area of ​​the heating top plate.

[0018] According to a specific implementation of the embodiment of the present application, the lower surface of the heating top plate is coated with a liquid-repellent coating.

[0019] According to a specific implementation of the embodiment of the present application, a liquid level detector is provided inside the thermal cavity for detecting the liquid level of the liquid heat transfer medium inside the thermal cavity.

[0020] According to a specific implementation of the embodiment of the present application, the method further includes:

[0021] The liquid external circulation unit is connected to the heat cavity and is configured to adjust the liquid level of the liquid heat transfer medium in the heat cavity to be within a preset range.

[0022] According to a specific implementation of the embodiment of the present application, the liquid external circulation unit includes a liquid storage tank and a liquid delivery pipeline, and the liquid storage tank is connected to the heat cavity through the liquid delivery pipeline.

[0023] According to a specific implementation of the embodiment of the present application, the liquid external circulation unit includes a power delivery unit;

[0024] The controller is configured to control the activation or deactivation of the power delivery unit to regulate the liquid heat transfer medium to enter or flow out of the liquid storage tank through the liquid delivery pipeline.

[0025] According to a specific implementation of the embodiment of the present application, the first gas delivery pipeline is connected to the liquid storage tank.

[0026] According to a specific implementation method of an embodiment of the present application, a cooling jacket is provided on the outer cover of the liquid storage tank, and the inner wall of the cooling jacket and the outer wall of the liquid storage tank together form a cooling cavity. A coolant inlet and a coolant outlet are provided on the cooling jacket. The coolant enters the cooling cavity through the coolant inlet to cool the liquid heat transfer medium inside the liquid storage tank, and then flows out through the coolant outlet.

[0027] The wafer baking device of the present invention utilizes the relationship between the boiling point of the liquid and the external pressure, and regulates the pressure in the heat chamber through a pressure control unit so that when the liquid heat transfer medium is heated, it boils at a preset boiling point corresponding to the preset pressure. The hot vapor generated by the boiling of the liquid heat transfer medium contacts the heating top plate surface, thereby achieving the purpose of heat conduction and obtaining better heating temperature uniformity.

[0028] In addition, the wafer baking device of the present invention has a zoned design for the heating top plate during the baking process, so that the heat loss during the process is concentrated in the transition area, so that the heat received by the wafer during the process is more uniform, further ensuring the uniformity of the heating temperature of the wafer.

[0029] In addition, the present invention also provides a liquid external circulation unit, which can not only adjust the amount of liquid heat transfer medium inside the heat cavity, but also recover the liquid heat transfer medium vapor discharged by the pressure control unit so that it can be further recycled and reused, thereby achieving the effect of saving resources and reducing costs.

[0030] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 A schematic structural diagram of a wafer baking device according to an embodiment of the present invention is shown;

[0033] Figure 2 Another structural schematic diagram of a wafer baking device according to an embodiment of the present invention is shown;

[0034] Figure 3 A schematic structural diagram of a heating top plate according to an embodiment of the present invention is shown;

[0035] Figure 4 shows another structural schematic diagram of a wafer baking device according to an embodiment of the present invention; and

[0036] Figure 5 A schematic diagram of another implementation structure of a wafer baking device according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0038] Please refer to Figure 1 The present invention provides a wafer baking device, including a thermal cavity 100, a heating unit 200 and a pressure control unit.

[0039] Specifically, the heat cavity 100 is surrounded by a bottom plate 101, side plates 102, and a heating top plate 103, and the heat cavity 100 is filled with a liquid heat transfer medium. In this embodiment, the heating top plate 103, the side plates 102, and the bottom plate 101 are integrally formed to improve their mechanical strength. It should be understood that in other examples, processes such as welding can also be used to assemble them, and the examples listed here are not limited. Furthermore, the liquid heat transfer medium is composed of one or more liquids. Exemplarily, the liquid heat transfer medium includes but is not limited to liquids such as water and oil.

[0040] The heating unit 200 is used to heat the liquid heat transfer medium to make the liquid heat transfer medium boil, and the hot vapor generated by the boiling liquid heat transfer medium heats the heating top plate 103 to improve the heating uniformity of the heating top plate 103, thereby improving the uniformity of the heating top plate 103 heating the wafer.

[0041] In this embodiment, the heating unit 200 is arranged inside the heat cavity 100, for example, at the bottom of the heat cavity 100, and the heating unit 200 is an electric heating wire, but is not limited to this. It can be selected and set according to needs. The specific type and position of the heating unit are not limited here.

[0042] The pressure control unit is configured to regulate the pressure in the heat cavity 100 to maintain it at a preset pressure, so that when the liquid heat transfer medium is heated, it boils at a preset boiling point corresponding to the preset pressure. The pressure control unit can control the boiling point of the liquid heat transfer medium by regulating the pressure in the heat cavity 100 because the boiling point of the liquid is related to the external pressure. Specifically, when the external pressure increases, the boiling point of the liquid increases; when the external pressure decreases, the boiling point of the liquid decreases, that is, under different external pressures, the liquid has different boiling points. Therefore, in the present application, the pressure control unit can regulate the pressure in the heat cavity 100 to a preset pressure corresponding to the preset boiling point of the liquid heat transfer medium based on the relationship between the boiling point of the liquid and the external pressure, so that the liquid heat transfer medium can boil at the preset boiling point. It should be noted that the pressure in the heat cavity 100 is the external pressure of the environment in which the liquid heat transfer medium is located.

[0043] In some embodiments, the pressure control unit includes a gas outlet 302, a pressure sensor 303, and a controller. The gas outlet 302 is disposed on the side panel 102 of the heat chamber 100 and is located above the liquid level of the liquid heat transfer medium. The gas outlet 302 is connected to a first gas delivery pipeline 305, which is provided with a first valve 3051. Opening or closing the first valve 3051 connects or closes the first gas delivery pipeline 305. The pressure sensor 303 is disposed within the heat chamber 100 to monitor the internal pressure of the heat chamber 100 in real time and transmit the pressure detection value to the controller. Furthermore, the pressure sensor 303 is disposed above the liquid heat transfer medium. The controller is configured to receive the pressure detection value from the pressure sensor 303 and control the opening or closing of the first valve 3051 based on the pressure detection value to regulate the pressure within the heat chamber 100.

[0044] Taking water as liquid heat transfer medium as an example Figure 1 The specific application of the wafer baking apparatus shown is illustrated as an example. When the wafer baking process requires a target process temperature of 119°C for heating the wafer, the preset boiling point of water is 119°C. According to the boiling point comparison table of water at different pressures, the preset boiling point corresponds to a preset pressure of 202.65 kPa. Therefore, the pressure control unit should control the pressure in the thermal chamber 100 to maintain 202.65 kPa. Before the baking process begins, an appropriate amount of water is injected into the heat chamber 100. The controller controls the first valve 3051 to close, and the heating unit 200 continues to heat the water. The heated water continuously generates hot steam, which continuously increases the pressure within the heat chamber 100. When the pressure value detected by the pressure sensor 303 exceeds 202.65 kPa, the pressure sensor 303 feeds the pressure value back to the controller, which controls the first valve 3051 to open, exhausting some of the gas from the heat chamber 100 to maintain the pressure within the heat chamber 100 at the preset pressure of 202.65 kPa. Since the pressure within the heat chamber 100 is stabilized at 202.65 kPa, the boiling point of the water in the heat chamber 100 can be stabilized at 119°C (i.e., the preset boiling point) after it is heated to boiling. At the same time, the temperature of the hot steam generated by the boiling water is the same as the boiling point of the water, also at 119°C. In order to make the heating top plate 103 heated more evenly, in the present application, the heating top plate 103 is heated by hot steam with stable temperature, so that the wafer can be heated evenly.

[0045] In another embodiment, the pressure control unit further includes a gas input port 301. Figure 2A gas inlet 301 is provided on the side panel 102 of the heat chamber 100 and is located above the liquid level of the liquid heat transfer medium. The gas inlet 301 is connected to a second gas delivery pipeline 304, which is provided with a second valve 3041. A controller controls the opening or closing of the second valve 3041, which determines whether the second gas delivery pipeline 304 is connected or closed. The gas inlet 301 can be used to pre-fill the heat chamber 100 with an appropriate amount of gas to regulate the pressure within the heat chamber 100.

[0046] Taking water as liquid heat transfer medium as an example Figure 2 The specific application of the wafer baking device shown is illustrated as an example. When the wafer baking process requires a target process temperature of 119°C for heating the wafer, the preset boiling point of water is 119°C. According to the boiling point comparison table of water at different pressures, the preset pressure corresponding to this preset boiling point is 202.65kPa. Therefore, the pressure control unit should adjust the pressure in the hot chamber 100 to maintain it at 202.65kPa. Before the process begins, an appropriate amount of water is injected into the hot chamber 100. At this time, the pressure in the hot chamber 100 is 101.3kPa at normal pressure. According to the boiling point comparison table of water at different pressures, the boiling point of water at normal pressure is 100°C. To ensure that the boiling point of water reaches the preset boiling point of 119°C, the pressure control unit can pre-regulate the pressure in the hot chamber 100. First, the first valve 3051 on the first gas delivery pipe 305 is closed, and the second valve 3041 on the second gas delivery pipe 304 is opened. The second gas delivery pipe 304 delivers gas (e.g., N2) into the heat chamber 100 through the gas inlet 301. At the same time, the pressure sensor 303 monitors the pressure in the heat chamber 100 in real time and feeds the pressure detection value back to the controller. When the pressure sensor 303 detects that the pressure detection value in the heat chamber 100 is a preset pressure corresponding to the preset boiling point, i.e., 202.65 kPa, the controller controls the second valve 3041 on the second gas delivery pipe 304 to close and controls the heating unit 200 to start heating the water. Since the water continuously generates hot vapor during the heating process, the hot vapor will increase the pressure in the heat chamber 100. In order to maintain a stable pressure in the heat chamber 100, the continuously generated hot vapor needs to be discharged.

[0047] The pressure control unit regulates the pressure within the heat chamber 100 to maintain a preset pressure as follows: when the pressure sensor 303 detects a pressure value greater than the preset pressure, the controller controls the first valve 3051 to open, allowing excess hot vapor to be discharged from the heat chamber 100 through the gas outlet 302 and the first gas delivery pipe 305. This process continues until the pressure sensor 303 detects a pressure value equal to the preset pressure, at which point the controller controls the first valve 3051 to close. When the pressure sensor 303 again detects a pressure value greater than the preset pressure, the controller controls the first valve 3051 to open again, discharging excess vapor. This process repeats, and the pressure control unit regulates the pressure within the heat chamber 100, stabilizing the pressure within the heat chamber 100 at 202.65 kPa. Consequently, after the water within the heat chamber 100 is heated to boiling, its boiling point stabilizes at 119°C (i.e., the preset boiling point). The temperature of the hot vapor generated by the boiling water is the same as the boiling point of the water, also at 119°C. After the liquid heat transfer medium has been heated to boiling for a predetermined time (illustratively, in this embodiment, the predetermined time is 3 minutes to 10 minutes), and the temperature of the heating top plate 103 has reached the target process temperature and is relatively stable, the wafer baking process begins, achieving stable and uniform heating of the wafers. When the baking process for a wafer is completed, the overall heating temperature of the heat chamber 100 is maintained (i.e., the liquid heat transfer medium in the heat chamber 100 is maintained at a boiling state at a preset pressure) to facilitate the baking process of the next wafer.

[0048] Furthermore, the heating plate 103 in the embodiment of the present invention is made of a material with high thermal conductivity, which helps improve heat transfer efficiency. Exemplary materials used for the heating plate 103 include, but are not limited to, aluminum nitride, silicon carbide, and the like. In the embodiment of the present invention, the material selected for the heating plate 103 is aluminum nitride.

[0049] The heating top plate 103 has some heat loss during the actual heat transfer process, especially in the edge area where the heat loss is more obvious. Therefore, during the process, the baking effect of the heating top plate on different parts of the wafer 400 will be different, affecting the wafer processing quality. To this end, a design is proposed, please refer to Figure 3 The heating plate 103 includes a process area 1031 and a transition area 1032. The process area 1031 is located in the middle of the heating plate 103 and is larger than or equal to the wafer size. The transition area 1032 is located at the edge of the heating plate 103 and surrounds the process area 1031, creating a certain distance between the process area 1031 and the edge of the heating plate 103. During the processing, the wafer 400 remains in the process area 1031, and the heat loss from the heating plate 103 is primarily concentrated in the transition area 1032, which does not affect the temperature of the process area 1031 corresponding to the wafer 400, thereby ensuring temperature uniformity across the processing area of ​​the wafer 400.

[0050] Furthermore, the lower surface of the heating plate 103 in the embodiment of the present invention is coated with a lyophobic coating. The lyophobic coating is formed from a material that repels liquid heat transfer media (e.g., PFA or PTFE). This makes it difficult for the liquid heat transfer medium to adhere to the lower surface of the heating plate 103, thereby preventing the liquid heat transfer medium from corroding the heating plate 103 after a long process. Furthermore, the lyophobic coating prevents the liquid heat transfer medium from condensing on the lower surface of the heating plate 103 to form droplets that adhere to the lower surface of the heating plate 103, thereby eliminating the impact of the condensation of the liquid heat transfer medium on the heat conduction effect of the heating plate 103.

[0051] Furthermore, a liquid level detector 500 is provided inside the thermal cavity 100 for detecting the liquid level of the liquid heat transfer medium inside the thermal cavity.

[0052] Considering that the amount of liquid heat transfer medium within the heat chamber 100 gradually decreases as the hot vapor is continuously exhausted, in order to ensure the safe and efficient execution of the process, the wafer baking apparatus of the present invention further includes a liquid external circulation unit 600. The liquid external circulation unit 600 is connected to the heat chamber 100 and is configured to regulate the liquid level of the liquid heat transfer medium within the heat chamber 100 to be within a preset range. During the actual process, the liquid level within the heat chamber 100 is measured using the liquid level detector 500. The liquid external circulation unit 600 regulates the liquid level within the heat chamber 100 based on the liquid level detection result to ensure that the liquid level of the liquid heat transfer medium within the heat chamber 100 is within the preset range.

[0053] Please refer to the Figure 4 The external liquid circulation unit 600 includes a liquid storage tank 601, a first liquid delivery pipeline 602, and a second liquid delivery pipeline 606. The liquid storage tank 601 is connected to the heat chamber 100 via the first and second liquid delivery pipelines 602 and 606. A valve 6021 is provided on the first liquid delivery pipeline 602. The opening and closing of valve 6021 determines whether the liquid storage tank 601 can deliver liquid heat transfer medium into the heat chamber 100. A valve 6061 is provided on the second liquid delivery pipeline 606. The opening and closing of valve 6061 determines whether the liquid heat transfer medium in the heat chamber 100 can be delivered to the liquid storage tank 601. In actual processing, to ensure a more stable and uniform temperature within the heat chamber 100 during the baking process, liquid replenishment is generally performed after the baking process is completed. To more efficiently replenish the heat chamber 100, the external liquid circulation unit 600 also includes a power delivery unit. The controller controls the start or shut down of the power delivery unit to achieve the purpose of regulating the liquid heat transfer medium from entering or flowing out of the liquid storage tank.

[0054] In some embodiments, the power delivery unit includes a second pump 6031. The second pump 6031 is an air pump that has both exhaust and inflation functions. The second pump 6031 is configured to regulate the pressure within the liquid storage tank 601. Specifically, a vent 604 is provided at the top of the liquid storage tank 601, and the second pump 6031 is disposed on a pipeline 6041 connected to the vent 604. The second pump 6031 delivers or extracts gas from the interior of the liquid storage tank 601 to regulate the pressure within the liquid storage tank 601, allowing the liquid heat transfer medium to enter the liquid storage tank 601 through the second liquid delivery pipeline 606 or the liquid heat transfer medium in the liquid storage tank 601 to flow out of the liquid storage tank 601 through the first liquid delivery pipeline 602. When the second pump 6031 inputs gas into the liquid storage tank 601 through the air vent 604, the internal pressure of the liquid storage tank 601 increases. At this time, the valve 6021 on the first liquid delivery pipeline 602 is opened, and the valve 6061 provided on the second liquid delivery pipeline 606 is closed. The liquid heat transfer medium will flow into the heat cavity 100 through the first liquid delivery pipeline 602, thereby achieving the effect of liquid replenishment; when the second pump 6031 extracts gas from the liquid storage tank 601 through the air vent 604, the internal pressure of the liquid storage tank 601 decreases. At this time, the valve 6021 on the first liquid delivery pipeline 602 is closed, and the valve 6061 on the second liquid delivery pipeline 606 is opened. The liquid heat transfer medium in the heat cavity 100 flows into the liquid storage tank 601 through the second liquid delivery pipeline 606, thereby achieving the effect of reducing the liquid heat transfer medium in the heat cavity 100.

[0055] Furthermore, considering that there may be a need to replenish the hot cavity 100 during the process, the present application provides a heater 6022 on the first liquid delivery pipeline 602. When the liquid level detector 500 detects the liquid level value in the hot cavity 100 and feeds it back to the controller, the controller determines that the detected liquid level value is lower than the preset value, and then controls the valve 6021 on the first liquid delivery pipeline 602 to open and the heater 6022 to turn on. At this time, the heating target temperature of the heater 6022 is the temperature of the liquid heat transfer medium inside the hot cavity 100 during the process (i.e., the preset boiling point). Through this design, it is possible to ensure that the liquid heat transfer medium inside the hot cavity 100 is maintained at a relatively ideal liquid level in real time, further ensuring the stable progress of the baking process.

[0056] In another embodiment, the power delivery unit includes a first pump 6062 and a third pump 6032. In this embodiment, the first pump 6062 is selectively provided on the second liquid delivery pipeline 606, and the third pump 6032 is selectively provided on the first liquid delivery pipeline 602. Figure 5 ,and Figure 4The difference between the illustrated example and the illustrated example is that the top of the liquid storage tank 601 is closed and no longer has a vent. When liquid needs to be added to the heat cavity 100, the valve 6021 on the first liquid delivery pipeline 602 and the third pump 6032 are opened to control the liquid heat transfer medium to flow into the heat cavity 100 through the first liquid delivery pipeline 602, thereby achieving the effect of liquid replenishment. When the liquid in the heat cavity 100 needs to be reduced, the valve 6021 on the first liquid delivery pipeline 602 is closed, the valve 6061 provided on the second liquid delivery pipeline 606 is opened, and the first pump 6062 provided on the second liquid delivery pipeline 606 is started, and the liquid heat transfer medium flows into the liquid storage tank 601 through the second liquid delivery pipeline 606, thereby achieving the purpose of reducing the liquid heat transfer medium in the heat cavity 100.

[0057] Further, see Figure 4 and Figure 5 The other end of the first gas delivery pipe 305 is connected to the bottom of the liquid storage tank 601 of the liquid external circulation unit 600. When the liquid in the heat chamber 100 continues to boil, the vaporization of the liquid causes the pressure in the heat chamber 100 to change. Once the pressure sensor 303 detects that the pressure inside the heat chamber 100 is greater than the preset pressure, the valve 3051 on the first gas delivery pipe 305 is opened to drain the hot vapor inside the heat chamber 100 and transport it through the first gas delivery pipe 305 to the liquid storage tank 601 of the liquid external circulation unit 600 for recycling and reuse.

[0058] Further, see Figure 4 and Figure 5 In order to improve the recovery efficiency, a cooling jacket 605 is provided on the outside of the liquid storage tank 601. The inner wall of the cooling jacket 605 and the outer wall of the liquid storage tank 601 together form a cooling cavity. A coolant inlet 6051 and a coolant outlet 6052 are provided on the cooling jacket 605. The coolant enters the cooling cavity through the coolant inlet 6051 to cool the liquid heat transfer medium inside the liquid storage tank 601, and then flows out through the coolant outlet 6052, continuously cooling the liquid storage tank 601, so that the liquid heat transfer medium entering the liquid storage tank 601 in a vapor state is quickly condensed to form a liquid liquid heat transfer medium.

[0059] The present invention utilizes the relationship between the boiling point of the liquid and the external pressure, and regulates the pressure in the heat cavity through a pressure control unit, so that when the liquid heat transfer medium is heated, it boils at a preset boiling point corresponding to the preset pressure, and the hot vapor generated by the boiling of the liquid heat transfer medium contacts the heating top plate surface, thereby achieving the purpose of heat conduction and obtaining better heating temperature uniformity.

[0060] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A wafer baking device, characterized in that: A heat cavity has a heating top plate and is filled with a liquid heat transfer medium; A heating unit, used for heating the liquid heat transfer medium and boiling the liquid heat transfer medium, and transferring heat to the heating top plate through hot vapor generated by the boiling of the liquid heat transfer medium; The pressure control unit is configured to regulate the pressure in the heat cavity to maintain it at a preset pressure, so that when the liquid heat transfer medium is heated, it boils at a preset boiling point corresponding to the preset pressure.

2. The wafer baking device according to claim 1, characterized in that: The pressure control unit includes a gas output port, a first gas delivery pipeline, a first valve, a pressure sensor and a controller; The gas outlet is arranged on the heat cavity and is located above the liquid level of the liquid heat transfer medium. The gas outlet is connected to the first gas delivery pipeline, and the first valve is arranged on the first gas delivery pipeline. The pressure sensor is arranged above the liquid heat transfer medium, and is used to monitor the internal pressure of the heat cavity in real time, and send the pressure detection value to the controller; The controller is configured to receive the pressure detection value, and when the liquid heat transfer medium is heated, control the opening or closing of the first valve according to the pressure detection value, so that the pressure in the heat chamber is maintained at the preset pressure.

3. The wafer baking device according to claim 2, characterized in that: The pressure control unit further comprises a gas input port, a second gas delivery pipeline and a second valve, wherein the gas input port is arranged on the heat cavity and is located above the liquid level of the liquid heat transfer medium, the gas input port is connected to the second gas delivery pipeline, and the second valve is arranged on the second gas delivery pipeline; The controller is further configured to control the opening or closing of the second valve.

4. The wafer baking device according to claim 1, characterized in that: The heating top plate includes a process area and a transition area; The process area is located in the middle area of ​​the heating top plate, and the size of the process area is greater than or equal to the size of the wafer to be heated; The transition area is located at the edge area of ​​the heating top plate.

5. The wafer baking device according to claim 1, characterized in that: The lower surface of the heating top plate is coated with a liquid-repellent coating.

6. The wafer baking device according to claim 2, characterized in that: A liquid level detector is arranged inside the thermal cavity to detect the liquid level of the liquid heat transfer medium inside the thermal cavity.

7. The wafer baking device according to claim 6, characterized in that: Also includes: The liquid external circulation unit is connected to the heat cavity and is configured to adjust the liquid level of the liquid heat transfer medium in the heat cavity to be within a preset range.

8. The wafer baking device according to claim 7, characterized in that: The liquid external circulation unit comprises a liquid storage tank and a liquid delivery pipeline, and the liquid storage tank is connected with the heat cavity through the liquid delivery pipeline.

9. The wafer baking device according to claim 8, characterized in that: The liquid external circulation unit includes a power delivery unit; The controller is configured to control the start or stop of the power delivery unit to regulate the liquid heat transfer medium to enter or flow out of the liquid storage tank through the liquid delivery pipeline.

10. The wafer baking device according to claim 8, characterized in that: The first gas delivery pipeline is in communication with the liquid storage tank.

11. The wafer baking device according to claim 10, characterized in that: A cooling jacket is provided on the outside of the liquid storage tank, and the inner wall of the cooling jacket and the outer wall of the liquid storage tank together form a cooling cavity. A coolant inlet and a coolant outlet are provided on the cooling jacket. The coolant enters the cooling cavity through the coolant inlet to cool the liquid heat transfer medium inside the liquid storage tank, and then flows out through the coolant outlet.

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