A low temperature evaporation source

Abstract

This invention provides a low-temperature evaporation source, comprising: an evaporation source body; a crucible disposed within the evaporation source body; liquid metal disposed between the crucible and the evaporation source body; an outer cooling water pipe fixed to the bottom of the evaporation source body, wherein a coaxial inner cooling water pipe is disposed within the outer cooling water pipe; a mounting flange connected to the outer cooling water pipe; a manual baffle actuator fixed to the mounting flange; a cooling water inlet pipe and a cooling water outlet pipe fixed to the mounting flange; and an electrode fixed to the mounting flange. The low-temperature evaporation source provided by this invention achieves efficient heat conduction by arranging liquid metal between the evaporation source body and the crucible, and by arranging a coaxial dual-channel cooling water pipe within the evaporation source body, thereby controlling the temperature of the evaporation source body between 10℃ and 300℃, allowing for rapid temperature adjustment and good temperature stability.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor equipment technology, and in particular to a low-temperature evaporation source. Background Technology

[0002] Molecular beam epitaxy (MBE) is a coating technique developed in the late 1960s. MBE has driven the development of semiconductor devices based on ultrathin microstructure materials, expanded the field of semiconductor science, and has since been widely applied in the growth of metals, insulators, and superconducting materials, playing a significant role in both basic research and industrial production. For achieving perfect MBE growth, the evaporation apparatus is particularly important, directly affecting the stability and uniformity of the molecular beam, the purity of the material, and the surface smoothness.

[0003] When growing materials using MBE equipment, the evaporation source typically used is either a thermal evaporation source or an electron beam evaporation source. Both types of evaporation sources use an electrically heated filament to heat the crucible and the material placed within it through radiation or electron beam heating, raising the material to the desired growth temperature, thus allowing the material to evaporate and grow. At higher temperatures, these two heating methods can achieve relatively stable temperature control, resulting in a stable growth beam. However, at low temperatures, especially at room temperature, precise temperature control is difficult to achieve. This is because these two heating methods can only control the heating power by adjusting the filament current, but cooling can only be achieved through natural radiation, without adjustable cooling power. At room temperature, the radiative cooling power is very low. At room temperature, if the temperature is too low, the heating power can be increased to raise the temperature; however, if the temperature is too high, even if the heating power is reduced to zero, the low cooling power means the temperature takes a long time to decrease and stabilize. Furthermore, the evaporation source temperature cannot be lowered below room temperature. When growing certain organic materials with relatively low growth temperatures, it is necessary to control the temperature of the evaporation source at a relatively low temperature, or even below room temperature. In this case, a low-temperature evaporation source is required. Utility Model Content

[0004] To address some or all of the problems in the existing technology, this utility model provides a low-temperature evaporation source, comprising:

[0005] Evaporation source body;

[0006] A crucible, which is arranged in the evaporation source body, is used to hold the material to be evaporated;

[0007] Liquid metal is disposed between the crucible and the evaporation source body, and the liquid metal is used to ensure thermal contact between the crucible and the evaporation source body;

[0008] The cooling water pipe outer tube is fixed to the bottom of the evaporation source body, and a coaxial cooling water pipe inner tube is arranged in the cooling water pipe outer tube;

[0009] The mounting flange is connected to the outer pipe of the cooling water pipe and is used to fix the low-temperature evaporation source to the vacuum chamber;

[0010] A manual baffle actuator, which is fixed on the mounting flange, is used to control the switch;

[0011] A cooling water inlet pipe and a cooling water outlet pipe are fixed to the mounting flange, and the cooling water inlet pipe and the cooling water outlet pipe are used for the introduction and discharge of cooling water; and

[0012] An electrode, which is fixed to the mounting flange, is used to power the heating filament and to read the thermocouple temperature.

[0013] Furthermore, the low-temperature evaporation source also includes:

[0014] An evaporator cover that encloses the evaporator body and is used to protect the internal components;

[0015] The outer cover fixing screws are used to fix the outer cover of the evaporation source.

[0016] Furthermore, the low-temperature evaporation source also includes:

[0017] A baffle, wherein the baffle is used to control the discharge of the material to be evaporated;

[0018] A baffle drive rod is arranged inside the outer casing of the evaporation source, and the baffle drive rod is used to control the movement of the baffle;

[0019] A crucible fixing plate is arranged at the top opening of the crucible, and the crucible fixing plate is used to fix the crucible; and

[0020] The pressure plate fixing screw is used to fix the crucible fixing pressure plate.

[0021] Furthermore, the liquid metal is gallium or a gallium-indium-tin alloy.

[0022] Furthermore, the melting point of the liquid metal is 5°C-8°C.

[0023] Furthermore, cooling water flows in through the inner pipe of the cooling water pipe and flows out through the gap between the inner pipe and the outer pipe of the cooling water pipe.

[0024] Furthermore, the low-temperature evaporation source also includes:

[0025] A closed heating chamber is formed, which is surrounded by the evaporation source body and the heater cover, and the heater cover is fixed to the evaporation source body by heater cover fixing screws;

[0026] A heating filament is arranged in the enclosed heating chamber. An insulating ceramic tube covers the side of the heating filament, and insulating ceramic sheets are arranged at the upper and lower ends of the heating filament to ensure electrical insulation between the heating filament and the evaporation source body and the heater cover.

[0027] Furthermore, the low-temperature evaporation source also includes:

[0028] A thermocouple is used to measure the temperature of the evaporation source body, and the thermocouple is fixed to the evaporation source body by thermocouple fixing screws.

[0029] Furthermore, the low-temperature evaporation source also includes:

[0030] The PID temperature control system is used to control the heating current of the heating filament, thereby controlling the temperature of the evaporation source body.

[0031] Furthermore, the temperature of the main body of the evaporation source is 10℃-300℃.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] 1. The low-temperature evaporation source provided by this utility model arranges liquid metal between the evaporation source body and the crucible to achieve efficient heat conduction, and arranges coaxial dual-channel cooling water pipes in the evaporation source body, thereby controlling the temperature of the evaporation source body in a wide range of 10℃-300℃, and can quickly adjust the temperature near room temperature, with good temperature stability.

[0034] 2. The low-temperature evaporation source provided by this utility model has a thermocouple directly placed on the main body of the evaporation source to read the temperature, and the heating current of the heating filament is controlled by a PID temperature control system, thereby accurately adjusting the temperature of the main body of the evaporation source.

[0035] 3. The low-temperature evaporation source provided by this utility model consists of an evaporation source body and a heater cover forming a closed heating chamber, which can transfer all the heat generated by the heating filament to the evaporation source body, reduce heat loss, and improve the energy utilization rate for heating the heating filament.

[0036] 4. The low-temperature evaporation source provided by this utility model designs the evaporation source components as modular components and uses flanges to install and fix them to the vacuum chamber, which improves the convenience of equipment maintenance. Attached Figure Description

[0037] To further illustrate the above and other advantages and features of the various embodiments of the present invention, a more specific description of the various embodiments of the present invention will be presented with reference to the accompanying drawings. It is understood that these drawings depict only typical embodiments of the present invention and are therefore not intended to limit its scope. In the drawings, for clarity, the same or corresponding parts will be indicated by the same or similar reference numerals.

[0038] Figure 1 A schematic diagram of the overall structure of a low-temperature evaporation source according to an embodiment of the present invention is shown;

[0039] Figure 2 A cross-sectional structural schematic diagram of a low-temperature evaporation source according to an embodiment of the present invention is shown;

[0040] Figure 3 A schematic diagram of the crucible and baffle according to an embodiment of the present invention is shown;

[0041] Figure 4 A schematic diagram of the evaporator source body and cooling water pipe according to an embodiment of the present invention is shown; and

[0042] Figure 5 A schematic diagram of the evaporation source body and heating shield according to an embodiment of the present invention is shown.

[0043] List of reference numerals

[0044] 1001 Mounting flange, 1002 Manual baffle actuator, 1003 Cooling water inlet pipe, 1004 Cooling water outlet pipe, 1005 Electrode, 1006 Evaporation source outer cover, 1007 Outer cover fixing screws, 1008 Cooling water outer pipe, 1009 Baffle, 1010 Crucible, 1011 Baffle drive rod, 1012 Crucible fixing plate, 1013 Plate fixing screws, 1014 Cooling water inner pipe, 1015 Evaporation source body, 1016 Thermocouple fixing screws, 1017 Liquid metal, 1018 Insulating ceramic sheet, 1019 Insulating ceramic tube, 1020 Heating filament, 1021 Heater cover, 1022 Heater cover fixing screws. Detailed Implementation

[0045] In the following description, the present invention is described with reference to various embodiments. However, those skilled in the art will recognize that the embodiments may be implemented without one or more specific details or with other alternatives and / or additional methods or components. In other instances, well-known structures or operations are not shown or described in detail so as not to obscure the inventive aspects of the present invention. Similarly, for illustrative purposes, specific numbers and configurations are set forth to provide a comprehensive understanding of embodiments of the present invention. However, the present invention is not limited to these specific details.

[0046] In this invention, unless otherwise specified, "arranged on" or "arranged above" does not exclude the possibility of an intermediate element between the two. Furthermore, "arranged on or above" merely indicates the relative positional relationship between two components, and under certain circumstances, such as when the product orientation is reversed, it can also be converted to "arranged below or under," and vice versa.

[0047] In this specification, references to "an embodiment" or "this embodiment" mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the present invention. The phrase "in one embodiment" appearing throughout this specification does not necessarily refer to all of the same embodiment.

[0048] It should be noted that the embodiments of this utility model use the terms "comprising", "including", "having", "containing" and / or "comprising", which, when used in this specification, indicate the presence of the stated features, elements and / or components, but do not exclude the presence or addition of one or more other features, elements, components and / or combinations thereof.

[0049] In this specification, the quantifiers “multiple” and “more” refer to one or more elements.

[0050] This invention provides a low-temperature evaporation source. Liquid metal is arranged between the evaporation source body and the crucible to achieve efficient heat conduction. Coaxial dual-channel cooling water pipes are arranged in the evaporation source body, which solves the problem of temperature control in the low-temperature section. Thus, the temperature of the evaporation source body can be controlled in a wide range of 10℃-300℃. The temperature can be quickly adjusted near room temperature, and the temperature stability is good.

[0051] The present invention will be further described below with reference to the accompanying drawings of the embodiments.

[0052] Figure 1 A schematic diagram of the overall structure of a low-temperature evaporation source according to an embodiment of the present invention is shown. Figure 2 A cross-sectional structural schematic diagram of a low-temperature evaporation source according to an embodiment of the present invention is shown. Figure 3 A schematic diagram of the crucible and baffle according to an embodiment of the present invention is shown. Figure 4 A schematic diagram of the evaporation source body and cooling water pipe according to an embodiment of the present invention is shown. Figure 5A schematic diagram of the evaporation source body and heating shield according to an embodiment of the present invention is shown. As shown in the figure, the low-temperature evaporation source includes a mounting flange 1001, a manual baffle actuator 1002, a cooling water inlet pipe 1003, a cooling water outlet pipe 1004, an electrode 1005, an evaporation source outer cover 1006, an outer cover fixing screw 1007, a cooling water pipe outer tube 1008, a baffle 1009, a crucible 1010, a baffle drive rod 1011, a crucible fixing plate 1012, a plate fixing screw 1013, a cooling water pipe inner tube 1014, an evaporation source body 1015, a thermocouple fixing screw 1016, liquid metal 1017, an insulating ceramic sheet 1018, an insulating ceramic tube 1019, a heating filament 1020, a heater shield 1021, and a heater shield fixing screw 1022.

[0053] As shown in the figure, the mounting flange 1001 is connected to the manual baffle actuator 1002, cooling water inlet pipe 1003, cooling water outlet pipe 1004, electrode 1005, and cooling water outer pipe 1008. The mounting flange 1001 is used to fix the low-temperature evaporation source into the vacuum chamber. In one embodiment, the mounting flange 1001 is a DN40CF type. The manual baffle actuator 1002 is fixed to the mounting flange 1001 and is used to control the switch. Here, the switch refers to the switch that controls the growth beam of the evaporation source; when the switch is turned on, the material to be evaporated evaporates to form a growth beam, and growth begins on the substrate; when the switch is turned off, the material to be evaporated stops forming a growth beam, thereby stopping growth on the substrate. The cooling water inlet pipe 1003 and the cooling water outlet pipe 1004 are fixed to the mounting flange 1001 and are used for the introduction and discharge of cooling water. Electrode 1005 is fixed to mounting flange 1001 and is used to power the heating filament and read the thermocouple temperature. Evaporator cover 1006 encloses the evaporator body 1015 and protects the internal components. Cover fixing screws 1007 are used to secure the evaporator cover. In one embodiment, the evaporator body 1015 may be made of copper. In another embodiment, the evaporator cover 1006 may be made of copper, molybdenum, or stainless steel.

[0054] The outer cooling water pipe 1008 is fixed to the bottom of the evaporator body 1015, and a coaxial inner cooling water pipe 1014 is arranged inside the outer cooling water pipe 1008. Cooling water flows in through the inner cooling water pipe 1014 and flows out through the gap between the inner cooling water pipe 1014 and the outer cooling water pipe 1008. During this process, the cooling water directly contacts the bottom of the evaporator body 1015, resulting in a large contact area and thus providing good cooling and sufficient cooling power to the evaporator body 1015. In one embodiment, the outer cooling water pipe 1008 and the inner cooling water pipe 1014 can also be arranged inside the evaporator body 1015 to further enhance the cooling power provided to the evaporator body 1015.

[0055] A crucible 1010 is arranged within an evaporation source body 1015 and is used to hold the material to be evaporated. In one embodiment, the crucible 1010 is a quartz crucible, which is of high purity, high temperature resistance, good thermal conductivity and insulation, low coefficient of thermal expansion, and does not react with most molten metals and semiconductor materials at high temperatures. Liquid metal 1017 is arranged between the crucible 1010 and the evaporation source body 1015. The liquid metal 1017 ensures excellent thermal contact between the crucible 1010 and the evaporation source body 1015, thereby ensuring that the material to be evaporated inside the crucible 1010 and the evaporation source body 1015 have the same temperature. In one embodiment, the liquid metal 1017 can be gallium or a gallium indium tin alloy. In one embodiment, the melting point of the liquid metal 1017 is 5°C-8°C. A baffle 1009 is arranged near the top opening of the crucible 1010 and is used to control the discharge of the material to be evaporated. A baffle drive rod 1011 is arranged inside the evaporation source outer casing 1006, and is used to control the movement of the baffle 1009. Specifically, moving the baffle 1009 covers the top opening of the crucible 1010, thus preventing the material to be evaporated from growing onto the substrate; moving the baffle 1009 does not cover the top opening of the crucible 1010, thus allowing the material to be evaporated to be discharged and grow onto the substrate. A crucible fixing plate 1012 is arranged at the top opening of the crucible 1010, and is used to fix the crucible 1010. A plate fixing screw 1013 is used to fix the crucible fixing plate 1012.

[0056] The heating assembly is placed within a closed heating chamber formed by the evaporator source body 1015 and the heater cover 1021. The heater cover 1021 is fixed to the evaporator source body 1015 by heater cover fixing screws 1022, ensuring good contact between the two. The heating assembly mainly includes an insulating ceramic sheet 1018, an insulating ceramic tube 1019, and a heating filament 1020. The heating filament 1020 is arranged within the closed heating chamber. The insulating ceramic tube 1019 covers the sides of the heating filament 1020, and the insulating ceramic sheet 1018 is arranged at the upper and lower ends of the heating filament 1020, ensuring electrical insulation between the heating filament 1020 and the evaporator source body 1015 and the heater cover 1021. The heat emitted by the heating filament 1020 after being energized is completely absorbed by the evaporator source body 1015 and the heater cover 1021. Because the evaporator source body 1015 and the heater cover 1021 are fixed together and have good thermal contact, the heat emitted by the heating filament 1020 is efficiently transferred to the evaporator source body 1015. In one embodiment, the insulating ceramic sheet 1018 and the insulating ceramic tube 1019 are made of ceramic, or sapphire. In one embodiment, the heating filament 1020 is a tantalum (Ta) heating filament, which is heat-resistant, has good ductility, does not become brittle after repeated heating, is easy to degas, and has a moderate resistivity.

[0057] Thermocouple (not shown in the figure) is used to measure the temperature of the evaporation source body 1015. The thermocouple is fixed to the evaporation source body 1015 by thermocouple fixing screw 1016.

[0058] When the low-temperature evaporator is operating, cooling water (e.g., water temperature 5℃, ambient temperature 20℃) flows through the cooling water inlet pipe 1003. Due to the excellent thermal contact between the cooling water and the evaporator body 1015, the evaporator body 1015 is quickly cooled to a temperature slightly higher than the cooling water temperature (e.g., 5.2℃). At this time, by applying different currents (i.e., different heating powers) to the heating filament 1020, the evaporator body 1015 can be heated to different temperatures. The PID temperature control system precisely controls the heating current of the heating filament 1020, thereby precisely controlling the temperature of the evaporator body 1015. Since all the heat generated by the filament heating 1020 is transferred to the evaporator body 1015, and the evaporator body 1015 has excellent thermal contact with the cooling water, the evaporator body 1015 can be quickly adjusted to the required temperature. The PID (Proportional Integral Derivative) temperature control system here is a system that uses proportional (P), integral (I), and derivative (D) control algorithms for temperature regulation. This PID temperature control system achieves precise temperature control by calculating the setpoint and the real-time values ​​fed back by the sensor.

[0059] The evaporation source body 1015 has very good thermal contact with the crucible 1010 through the liquid metal 1017, which allows the crucible 1010 (and the material to be evaporated placed in the crucible) to be quickly adjusted to the required temperature.

[0060] The low-temperature evaporation source provided by this utility model can be used in a temperature range of 10℃-300℃, which can be lower than room temperature.

[0061] The low-temperature evaporation source provided by this invention utilizes liquid metal arranged between the evaporation source body and the crucible to achieve efficient heat conduction. A coaxial dual-channel cooling water pipe is arranged within the evaporation source body, thereby controlling the temperature of the evaporation source body within a wide range of 10℃-300℃. The temperature can be rapidly adjusted near room temperature, exhibiting good temperature stability. Thermocouples are directly placed on the evaporation source body to read the temperature, and a PID temperature control system controls the heating current of the heating filament, allowing for precise temperature adjustment. The evaporation source body and heater cover enclose a sealed heating chamber, transferring all the heat generated by the heating filament to the evaporation source body, reducing heat loss and improving the energy utilization rate for heating the filament. The evaporation source components are designed as modular parts, using flanges for mounting and fixing to the vacuum chamber, enhancing the convenience of equipment maintenance.

[0062] Although various embodiments of the present invention have been described above, it should be understood that they are presented by way of example only and not as limitations. It will be apparent to those skilled in the art that various combinations, modifications, and alterations can be made without departing from the spirit and scope of the present invention. Therefore, the breadth and scope of the present invention disclosed herein should not be limited to the exemplary embodiments disclosed above, but should be defined only according to the technical solutions and their equivalents.

Claims

1. A low-temperature evaporation source, characterized in that, include: Evaporation source body; A crucible, which is arranged in the evaporation source body, is used to hold the material to be evaporated; Liquid metal is disposed between the crucible and the evaporation source body, and the liquid metal is used to ensure thermal contact between the crucible and the evaporation source body; The cooling water pipe outer tube is fixed to the bottom of the evaporation source body, and a coaxial cooling water pipe inner tube is arranged in the cooling water pipe outer tube; The mounting flange is connected to the outer pipe of the cooling water pipe and is used to fix the low-temperature evaporation source to the vacuum chamber; A manual baffle actuator, which is fixed on the mounting flange, is used to control the switch; A cooling water inlet pipe and a cooling water outlet pipe are fixed on the mounting flange. The cooling water inlet pipe and the cooling water outlet pipe are used for the introduction and discharge of cooling water. as well as An electrode, which is fixed to the mounting flange, is used to power the heating filament and to read the thermocouple temperature.

2. The low-temperature evaporation source according to claim 1, characterized in that, Also includes: An evaporator cover that encloses the evaporator body and is used to protect the internal components; The outer cover fixing screws are used to fix the outer cover of the evaporation source.

3. The low-temperature evaporation source according to claim 1 or 2, characterized in that, Also includes: A baffle, wherein the baffle is used to control the discharge of the material to be evaporated; A baffle drive rod is arranged inside the outer casing of the evaporation source, and the baffle drive rod is used to control the movement of the baffle; A crucible fixing plate is arranged at the top opening of the crucible, and the crucible fixing plate is used to fix the crucible; and The pressure plate fixing screw is used to fix the crucible fixing pressure plate.

4. The low-temperature evaporation source according to claim 1, characterized in that, The liquid metal is gallium or a gallium-indium-tin alloy.

5. The low-temperature evaporation source according to claim 1, characterized in that, The melting point of the liquid metal is 5℃-8℃.

6. The low-temperature evaporation source according to claim 1, characterized in that, Cooling water flows in through the inner pipe of the cooling water pipe and flows out through the gap between the inner pipe and the outer pipe of the cooling water pipe.

7. The low-temperature evaporation source according to claim 1, characterized in that, Also includes: A closed heating chamber is formed, which is surrounded by the evaporation source body and the heater cover, and the heater cover is fixed to the evaporation source body by heater cover fixing screws; A heating filament is arranged in the enclosed heating chamber. An insulating ceramic tube covers the side of the heating filament, and insulating ceramic sheets are arranged at the upper and lower ends of the heating filament to ensure electrical insulation between the heating filament and the evaporation source body and the heater cover.

8. The low-temperature evaporation source according to claim 1, characterized in that, Also includes: A thermocouple is used to measure the temperature of the evaporation source body, and the thermocouple is fixed to the evaporation source body by thermocouple fixing screws.

9. The low-temperature evaporation source according to claim 1, characterized in that, Also includes: The PID temperature control system is used to control the heating current of the heating filament, thereby controlling the temperature of the evaporation source body.

10. The low-temperature evaporation source according to claim 9, characterized in that, The temperature of the main body of the evaporation source is 10℃-300℃.

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