Circular lamp tube wafer heater, annealing furnace system and temperature control method

Abstract

The invention relates to a round lamp tube wafer heater, an annealing furnace system and a temperature control method, and relates to the technical field of wafer processing, the round lamp tube wafer heater comprises a heater base, a plurality of heating lamp tubes, a pyrometer and a lamp tube power divider, the plurality of heating lamp tubes are arranged on the heater base to form a plurality of concentric circles, the pyrometer is arranged corresponding to the middle of a heating lamp tube arrangement area, the lamp tube power divider comprises a temperature control unit and a plurality of power control elements, and the plurality of heating lamp tubes are electrically connected with the plurality of power control elements respectively. And the temperature control unit is electrically connected with the pyrometer and the plurality of power control elements, so that the heating power of each heating lamp tube can be respectively controlled according to the detection result of the pyrometer, and the uniformity of the wafer heating temperature can be improved. The invention further discloses a wafer annealing furnace system using the circular lamp tube wafer heater and a temperature control method of the wafer annealing furnace system.

Description

Technical Field

[0001] The present application relates to the field of wafer processing technology, and in particular to a round tube wafer heater. In addition, the present application also relates to a wafer annealing furnace system and a temperature control method for the wafer annealing furnace system. Background Art

[0002] A wafer refers to a silicon chip used to make silicon semiconductor circuits. It is a silicon wafer formed by grinding, polishing and slicing silicon crystal rods. It is the basic material for manufacturing integrated circuits and other semiconductor components, and plays an extremely important role in today's information society.

[0003] In semiconductor processing, as a rapid thermal processing process, the wafer needs to be heated and annealed multiple times. Such as metal annealing after metal deposition, crystallization after implantation process, and rapid thermal oxidation (RTO) for preparing thermal oxide film, etc. When heating and annealing the wafer, it is necessary to ensure the uniformity of temperature at different positions of the wafer to ensure the uniformity of the wafer structure and the uniformity of the film thickness on the wafer surface.

[0004] In the existing wafer annealing furnace system, a disc-shaped heater is usually used to heat the wafer. In order to ensure the uniformity of heating in different areas of the disc heater, multiple heating elements are usually set in different areas of the disc heater, and multiple temperature sensors are set at different positions in the furnace chamber. The heating power of different heating elements is adjusted according to the temperature difference detected by the multiple temperature sensors to ensure the consistency of heating temperature at different positions of different wafers. However, the temperature uniformity of heating the wafer is required to be high. It is usually necessary to set a large number of heating elements and temperature sensors in the wafer area. The multiple heating elements are independently controlled by the detection results of multiple temperature sensors. The circuit setting is relatively complicated, which increases the risk of circuit failure. In order to reduce the number of temperature sensors, a method has recently emerged in which the temperature sensors are set along the radial direction of the wafer position, a large number of heating elements are set, the heating elements are grouped and connected in parallel into a small number of heating zones, and the wafer is driven to rotate relative to the disc heater to ensure the uniformity of the wafer heating temperature. This method requires temperature control of the relative rotating area, and the control method is very complicated. In addition, the number of temperature sensors and heating elements is large, which affects the utilization rate of the equipment and is not conducive to the maintenance and repair of the equipment. Summary of the invention

[0005] In order to simplify the structure of the wafer heater and improve the temperature uniformity in the annealing furnace, the present application provides a circular lamp tube wafer heater, an annealing furnace system and a temperature control method.

[0006] The circular lamp tube wafer heater provided in this application adopts the following technical solution: A circular lamp tube wafer heater comprises a heater seat, a heating lamp tube, a pyrometer and a lamp tube power distributor, wherein a plurality of the heating lamp tubes are arranged in a plurality of mutually concentric circles on the heater seat, the pyrometer is arranged corresponding to the middle of the heating lamp tube setting area, the lamp tube power distributor comprises a temperature control unit and a plurality of power control elements, the plurality of heating lamp tubes are electrically connected to the plurality of power control elements respectively, the temperature control unit is electrically connected to the pyrometer and the plurality of power control elements so as to be able to control the heating power of each heating lamp tube respectively according to the detection result of the pyrometer.

[0007] By adopting the above technical scheme, a plurality of heating lamps arranged in concentric circles can be used to form a uniform heating area for the heating lamps around the center of the circle, which is beneficial to ensuring the uniformity of temperature in the area where the heating lamps are set; a pyrometer set in the middle of the area where the heating lamps are set can be used to detect the real-time temperature of the heating area during the heating process, so that the heating lamps can be controlled to form different heating powers at different heating temperatures; a temperature control unit in a lamp power distributor can be used to control a plurality of power control elements separately, and the heating powers of the plurality of heating lamps can be controlled separately through the power control elements, so as to ensure the temperature uniformity of the heating areas of different heating lamps.

[0008] In a specific possible implementation manner, a metal reflector is provided between the heating lamp tube and the heater base.

[0009] By adopting the above technical solution, using a metal reflector arranged between the heating lamp tube and the heater seat, on the one hand, the heat source light emitted by the heating lamp tube can be reflected more toward the wafer direction, thereby improving the heating efficiency of the heating lamp tube; on the other hand, the heat radiation from the heating area can be reflected, reducing the transfer of heat to the heater seat, reducing the temperature of the heater seat and the resulting heat energy loss.

[0010] In a specific possible implementation manner, a cooling water circulation unit is provided between the heater seat and the metal reflector, a cooling water temperature sensor is provided on the heater seat, and both the cooling water circulation unit and the cooling water temperature sensor are electrically connected to the temperature control unit.

[0011] By adopting the above-mentioned technical scheme, a cooling water circulation unit is arranged between the heater seat and the metal reflector, so that the external temperature of the wafer heater can be effectively controlled, which is beneficial to ensuring the working stability of the external components of the wafer heater; using the cooling water temperature sensor arranged on the heater seat, the working condition of the cooling water circulation unit can be monitored in real time, and the failure of the cooling water circulation unit can be prevented from causing the external temperature of the wafer heater to be too high.

[0012] In a specific implementation scheme, the pyrometer is arranged on a side of the wafer to be processed away from the heating lamp, a focusing lens is arranged between the wafer and the pyrometer, and the focus of the focusing lens is located at the temperature sensing element area of ​​the pyrometer.

[0013] By adopting the above technical solution and utilizing a focusing lens disposed between the wafer and the pyrometer, the thermal radiation generated by the heated wafer can be focused more on the temperature sensing element area of ​​the pyrometer, so that the pyrometer can detect temperature values ​​within a larger range of the wafer and improve the sensitivity of the pyrometer to wafer heating temperature detection.

[0014] In a specific implementation manner, the number of the heating lamp tubes is the same as the number of the power control elements, and each of the heating lamp tubes is connected to a different power control element in a one-to-one correspondence.

[0015] By adopting the above technical solution and utilizing the one-to-one correspondence between heating lamps and power control elements, the heating power of multiple heating lamps can be independently controlled through different power control elements, thereby enabling more precise adjustment of the heating temperature of different areas of the wafer heater, thereby ensuring the uniformity of the heating temperature at different positions of the wafer.

[0016] In a specific possible implementation scheme, a power allocation storage element is provided in the temperature control unit, and the power allocation storage element stores the power ratio of each power control element corresponding to different pyrometer detection temperatures. The temperature control unit can call the power ratio value stored in the power allocation storage element according to the temperature value detected by the pyrometer to control the power ratio of each power control element.

[0017] By adopting the above technical solution and utilizing the power ratio values ​​of different power control elements stored in the power distribution storage element, the heating power of each heating lamp tube can be controlled separately through the heating temperature detected by a single pyrometer, thereby ensuring the uniformity of the heating temperature in different areas of the wafer heater.

[0018] The wafer annealing furnace system provided in this application adopts the following technical solutions: A wafer annealing furnace system comprises a furnace body and the circular lamp tube wafer heater of the present application, wherein a furnace cavity is arranged in the upper part of the furnace body, the circular lamp tube wafer heater is arranged at the opening of the furnace cavity, a heat conductive support ring for supporting wafers is arranged in the furnace cavity, the heat conductive support ring is arranged concentrically with the heating lamp tube, and the pyrometer is arranged at the bottom of the furnace cavity and is located in the middle area of ​​the heat conductive support ring.

[0019] By adopting the above-mentioned technical scheme, the wafer can be supported in a cavity separated from the furnace cavity wall by using a heat-conducting support ring arranged in the furnace cavity, thereby preventing metal impurities in the furnace cavity wall from seeping into the wafer and affecting the purity of the wafer material, and being able to form a stable heating area in the area where the wafer is located, which is beneficial to improving the uniformity of the wafer heating temperature; using the circular lamp tube wafer heater of the present application, different areas of the heater can be heated evenly, ensuring the uniformity of the heating temperature at different positions of the wafer during the annealing process.

[0020] The temperature control method of the wafer annealing furnace system provided in this application adopts the following technical solution: A temperature control method for a wafer annealing furnace system of the present application comprises the following steps: S10, presetting the initial power ratio of each heating lamp in the temperature control unit; S20, setting a calibration temperature sensor and a plurality of debugging temperature sensors in the furnace chamber, wherein the calibration temperature sensor is arranged relative to the pyrometer, and the debugging temperature sensors are dispersedly arranged at different positions around the calibration temperature sensor; S30, controlling the actual heating power of each corresponding heating lamp to heat by using the initial power ratio, and calibrating the detection value of the pyrometer by using the calibration temperature sensor; S40, calibrating the detection value of the pyrometer according to different values ​​of the debugging temperature sensors; The difference between the detected temperature and the temperature value detected by the pyrometer is used to adjust the power ratio of the debugging temperature sensor adjacent to the tube heater, so that the detection values ​​of different debugging temperature sensors tend to be consistent; S50, the power ratios of different heating lamps of the pyrometer at different temperatures are stored in the temperature control unit, replacing the initial power ratio value preset in the temperature control unit; S60, the calibration temperature sensor and the debugging temperature sensor are removed, the wafer to be processed is placed in the furnace chamber, the heating power of each heating lamp is controlled according to the power ratio at different temperatures stored in the temperature control unit, and the annealing operation of the wafer to be processed is performed.

[0021] By adopting the above technical scheme, the calibration temperature sensor arranged opposite to the pyrometer can be used to determine the deviation between the actual temperature of the wafer and the temperature value detected by the pyrometer, so as to adjust the temperature value detected by the pyrometer, so that the temperature detection value of the pyrometer can accurately reflect the actual temperature of the wafer; the debugging temperature sensors dispersedly arranged at different positions around the calibration temperature sensor in the furnace chamber can be used to detect the temperatures of different parts of the wafer when each heating lamp tube works under a preset power ratio, and the power ratio values ​​of different heating lamp tubes are adjusted according to the difference between the actual temperature of different parts of the wafer and the temperature detected by the pyrometer, so that the temperature difference of different parts of the wafer meets the set requirements, and then the actual power ratio of different heating lamp tubes that can ensure the uniformity of wafer temperature is stored in the temperature control unit, replacing the initial power ratio value preset in the temperature control unit, so that the heating power of different heating lamp tubes at different temperatures can be controlled according to the newly stored power configuration value, so as to ensure the uniformity of heating temperature of different parts of the wafer.

[0022] In a specific possible implementation, in step S20, a plurality of thermocouples are arranged on the test wafer, the test wafer is placed on the thermally conductive support ring, and a calibration temperature sensor and a plurality of debugging temperature sensors are arranged in the furnace chamber.

[0023] By adopting the above technical solution, a calibration temperature sensor and an adjustment temperature sensor are set in the furnace chamber by using the method of setting a thermocouple on the test wafer, which can facilitate the temporary setting of the temperature sensor in the furnace chamber and make the temperature test environment in the furnace chamber closer to the actual use environment.

[0024] In a specific feasible implementation scheme, in step S40, a PIDT controller is set in the temperature control unit, and the power ratio of the different tube heaters adjacent to the debugging temperature sensor is adjusted using the P, I, D, and T values ​​stored in the PIDT controller, and the P, I, D, and T values ​​stored in the PIDT controller are adjusted according to the difference between the adjusted temperature and the temperature detected by the pyrometer.

[0025] By adopting the above technical solution and using the PIDT controller set in the temperature control unit, it is possible to use the detection results of a small number of test temperature sensors to independently control and adjust the heating power of a large number of surrounding light heaters, thereby forming a different power ratio for each heating lamp tube and ensuring the uniformity of the wafer heating temperature in the furnace chamber.

[0026] In summary, the present application includes at least one of the following beneficial technical effects: 1. By arranging a plurality of heating lamps arranged in concentric circles in the heater seat and a lamp power distributor connected to each heating lamp, the heating power of the heating lamps at different positions on the heater seat can be controlled separately, so that the heating power of the heating lamps at different positions is adapted to the working environment of the heating lamps, thereby ensuring the uniformity of the heating temperature at different positions.

[0027] 2. The power allocation storage unit in the temperature control unit can be used to store the power ratio of each heating lamp tube that can ensure the uniformity of the heating temperature at different heating temperatures. The actual heating temperature of the wafer heater is detected according to a single pyrometer, and the power ratio stored in the power allocation storage unit is called to perform real-time control of the heating power of each heating lamp tube to ensure the uniformity of the heating temperature at different positions of the wafer heater. The structure of the wafer heater is simpler and the power control of multiple heating lamp tubes is more convenient.

[0028] 3. By setting multiple thermocouples on the test wafer, the actual heating temperatures at multiple different positions under different temperature states during the wafer heating process can be measured, and the deviation between the pyrometer and the thermocouple measurement values ​​can be corrected, and the power ratio of each heating lamp tube can be adjusted according to the difference between the actual heating temperature at different positions and the pyrometer detection temperature, so as to obtain the power ratio value of each heating lamp tube that can ensure the uniformity of wafer heating temperature, so as to control the actual heating power of each heating lamp tube at different temperatures during actual operation, and ensure the uniformity of heating temperature at different positions of the wafer.

[0029] 4. Through the PIDT controller in the temperature control unit, the detection values ​​of a small number of temperature sensors can be used to adjust the heating power of a large number of heating lamps at different positions around the wafer, balance the impact of the heating power changes of each heating lamp on the heating temperature of the wafer, simplify the adjustment process of the power ratio of each heating lamp, and ensure the consistency of the adjustment results with the actual working process. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of an embodiment of a circular lamp tube wafer heater of the present application.

[0031] Figure 2 This is a schematic diagram of the distribution of heating lamp tubes in one embodiment of a circular lamp tube wafer heater of the present application.

[0032] Figure 3 This is a schematic diagram of the temperature control structure of a circular lamp tube wafer heater in one embodiment of the present application.

[0033] Figure 4 This is a functional structure block diagram of a temperature control unit in one embodiment of a circular lamp tube wafer heater of the present application.

[0034] Figure 5 This is a schematic structural diagram of an embodiment of a wafer annealing furnace system of the present application.

[0035] Figure 6 It is a cross-sectional schematic diagram of an embodiment of a wafer annealing furnace system of the present application.

[0036] Figure 7 This is a schematic diagram of the relative positions of the temperature sensor and the heating lamp in one embodiment of the temperature control method of the wafer annealing furnace system of the present application.

[0037] Figure 8 The present invention is a flowchart of an embodiment of a temperature control method of a wafer annealing furnace system of the present invention.

[0038] Fig. 9 This is a comparison chart of the detection values ​​of the calibrated temperature sensor and the pyrometer in one embodiment of the temperature control method of the wafer annealing furnace system of the present application.

[0039] Fig.10 This is a temperature state diagram of different heating stages in one embodiment of a temperature control method for a wafer annealing furnace system of the present application.

[0040] Fig.11 This is a temperature comparison diagram of different positions of the wafer during the same heating process after adjustment using an embodiment of the temperature control method of the wafer annealing furnace system of the present application.

[0041] Fig.12 This is a schematic diagram of temperature control states in different heating stages in another embodiment of the temperature control method for a wafer annealing furnace system of the present application.

[0042] Fig.13 This is a comparison diagram of the control effect of the oxide layer thickness of wafers processed in one embodiment of the temperature control method of the wafer annealing furnace system of the present application.

[0043] Fig.14 A schematic diagram of repeatability verification of an embodiment of a temperature control method for a wafer annealing furnace system of the present application.

[0044] Explanation of the reference numerals: 1. heater seat; 11. cooling water circulation unit; 12. cooling water temperature sensor; 13. heater cover; 14. lamp power supply interface; 2. heating lamp; 21. support ring range line; 22. wafer range line; 3. pyrometer; 31. focusing lens; 4. lamp power distributor; 41. temperature control unit; 411. power distribution storage element; 412. PIDT controller; 42. power control element; 5. metal reflector; 6. furnace body; 61. furnace cavity; 62. heat conductive support ring; 63. cooling unit; 64. air inlet; 65. air outlet pipe; 7. wafer; 8. debugging wafer; 81. calibration temperature sensor; 82. modulation temperature sensor. DETAILED DESCRIPTION

[0045] The specific implementation of the present application is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present application, and is not used to limit the present application.

[0046] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0047] An embodiment of the circular lamp wafer heater of the present application is as follows: Figures 1 to 3 As shown, it includes a heater seat 1, a heating lamp tube 2, a pyrometer 3 and a lamp tube power distributor 4. The heater seat 1 is usually a disc-shaped seat structure made of aluminum alloy material, which can also be called an aluminum chamber. The heating lamp tube 2 can use various suitable lamp tube-shaped heaters. The heating structure of the lamp tube-shaped heater is encapsulated inside the lamp tube, which can reduce the escape of metal atoms in the heating structure under high temperature and the pollution of the crystal structure of the heated wafer 7. A plurality of heating lamp tubes 2 are provided, and the plurality of heating lamp tubes 2 are arranged on the same side of the heater seat 1, and are arranged on the heater seat 1 to form a plurality of mutually concentric circles.

[0048] The pyrometer 3 can be arranged on the heater base 1 or outside the heater base 1. The pyrometer 3 is arranged at a position corresponding to the middle area of ​​the area where the heating lamp tubes 2 are arranged, and is usually arranged at a position corresponding to the center of the concentric circles formed by the plurality of heating lamp tubes 2. The pyrometer 3 is arranged toward the wafer 7 to monitor the real-time temperature of the wafer 7 at different heating times during the heating process.

[0049] The lamp power distributor 4 can be arranged on the side of the heater base 1 opposite to the heating lamp 2, or can be arranged outside the heater base 1, and connected to each heating lamp 2 through a wire passing through the heater base 1. The lamp power distributor 4 includes a temperature control unit 41 and a plurality of power control elements 42. The temperature control unit 41 can use various suitable controllers or microprocessors, such as a single-chip microcomputer, a PLC controller, etc. The power control element 42 usually uses a thyristor, and other power control elements with similar functions can also be used.

[0050] For example, a circular lamp tube wafer heater for heating a 12-inch wafer 7 is provided with 71 heating lamp tubes 2, and the 71 heating lamp tubes 2 are arranged on a heater seat 1 as follows: Figure 2 The 15 concentric circles are numbered from the inner layer to the outer layer, and the number of heating lamps 2 on each concentric circle and the rated total power distribution of the heating lamps 2 are shown in Table 1. Among them, the diameter of the outer concentric circle is larger than the diameter of the wafer 7. Usually, the arrangement range of the heating lamps 2 is four to five concentric circles larger than the wafer range line corresponding to the wafer 7.

[0051] Table 1 Number and power distribution of heating lamps on different concentric circles Each heating lamp tube 2 is connected to a power control element 42 through a power supply line. A power control element 42 can be individually provided for each heating lamp tube 2, or a power controllable element 42 can be provided for several adjacent heating lamp tubes 2. Using one power control element 42 to control several heating lamp tubes 2 can reduce the number of power control elements 42 to be provided, reduce production and use costs, and simplify the control process.

[0052] The temperature control unit 41 is electrically connected to the pyrometer 3 and each power control element 42. The power ratio of each power control element 42 in each heating temperature section that can ensure the temperature uniformity of different parts of the heating area of ​​the wafer 7 is stored inside the temperature control unit 41. The temperature control unit 41 can call the power ratio value of each power control element 42 stored inside according to the temperature detected by the pyrometer 3, and use the power ratio value to control the working state of each power control element 42, thereby controlling the heating power of each heating lamp tube 2 connected to each power control element 42, and ensuring the temperature uniformity of different parts of the heating area of ​​the circular lamp tube wafer heater 7.

[0053] The existing wafer heaters that ensure temperature uniformity by rotation usually have a maximum temperature difference of about 10°C in different areas during the insulation stage. With the circular lamp tube wafer heater of the present application, the maximum temperature difference in different areas during the insulation stage can be reduced to about 3°C ​​after debugging, which greatly improves the uniformity of wafer heating temperature. Moreover, when using the circular lamp tube wafer heater of the present application, there is no need to set a rotating motion structure, which greatly improves the reliability of the equipment and reduces the equipment maintenance and repair costs.

[0054] In some embodiments of the circular lamp wafer heater of the present application, as Figure 2 and Figure 6 As shown, a metal reflector 5 is provided between the heating lamp tube 2 and the heater base 1. The metal reflector 5 can reflect more heat radiation generated by the heating lamp tube 2 toward the heating surface, thereby improving the thermal efficiency of the heating lamp tube 2.

[0055] In a preferred embodiment of the circular lamp wafer heater of the present application, as Figure 1 and Figure 3 As shown, a cooling water circulation unit 11 is provided between the heater seat 1 and the metal reflector 5. The cooling water circulation unit 11 can cool the outer side of the heater seat 1 to prevent the outer side of the heater seat 1 from being overheated and causing damage to other external components.

[0056] A cooling water temperature sensor 11 is also provided on the heater seat 1 for monitoring the working condition of the cooling water circulation unit 11. When the cooling water temperature sensor 11 detects that the temperature of the cooling water after passing through the cooling water circulation unit 11 is abnormal, it can be judged that the cooling water circulation unit 11 is working abnormally, which may easily cause the temperature in the heater seat 1 to be too high. At this time, the heating temperature of the heating lamp 2 can be limited, and a fault alarm can be issued at the same time.

[0057] The cooling water circulation unit 11 and the cooling water temperature sensor 12 are both connected to the temperature control unit 41 through wires. The temperature control unit 41 can control the operating state of the cooling water circulation unit 11 according to the detection result of the cooling water temperature sensor 12, and temporarily limit the heating power of the heating lamp 2 when the cooling water circulation unit 11 fails.

[0058] In some embodiments of the circular lamp wafer heater of the present application, as Figure 3 As shown, the pyrometer 3 is arranged on the side of the wafer 7 away from the heating lamp 2, so that the pyrometer 3 and the heating lamp 2 are respectively located on both sides of the wafer 7 to be heated. A focusing lens 31 is arranged between the wafer 7 and the pyrometer 3, and the focusing lens 31 uses an optical lens that can withstand a high temperature environment, such as a quartz glass lens. The focusing lens 31 is arranged in the middle of the area where the heating lamp 2 is arranged, and its focus is arranged in the temperature sensing element area of ​​the pyrometer 3, which can focus the heat radiation generated by the wafer 7 in a larger range after being heated to the temperature sensing element of the pyrometer 3, so that the temperature value detected by the pyrometer 3 can reflect the temperature in a larger range on the wafer 7, improve the sensitivity of the heating temperature of the heating lamp 2 detected by the pyrometer 3, and help to improve the stability of the temperature detection value.

[0059] In some embodiments of the circular lamp tube wafer heater of the present application, the number of heating lamp tubes 2 is the same as the number of power control elements 42, and each heating lamp tube 2 is connected to a different power control element 42 in a one-to-one correspondence. In this way, the power control element 42 can be used to control the heating power of each lamp tube heater individually, so that the heating temperature of different parts of the lamp tube wafer heater can be controlled more precisely, and the uniformity of the heating temperature of different parts can be better ensured.

[0060] In a preferred embodiment of the circular lamp wafer heater of the present application, as Figure 3As shown, a power allocation storage element 411 for storing the power ratio for controlling each power control element 42 under different temperature states is provided in the temperature control unit 41. The power ratio is stored in the form of a control signal capable of controlling the percentage of the actual heating power of the heating lamp 2 under the control of the temperature control element 42 to its rated power. For the thyristor, the power ratio is stored in the power allocation storage element 411 in the form of a trigger signal capable of controlling the trigger angle of the thyristor.

[0061] In the power allocation storage element 411, the power ratio control signal of each power control element 42 under the temperature states of different temperature segments detected by the pyrometer 3 is stored. When the temperature value detected by the pyrometer 3 is in different temperature segments, the temperature control unit 41 can call the power ratio value stored in the power allocation storage element 411 to generate a control signal for controlling the control state of each power control element 42, such as controlling the size of the thyristor trigger angle, and controlling the ratio of the actual heating power of the heating lamp 2 connected to each power control element 42 to the rated power, thereby controlling the temperature of each part of the heating lamp 2, so that the temperature of different parts of the wafer 7 heated by the lamp wafer heater is more uniform.

[0062] An embodiment of the wafer annealing furnace system of the present application is as follows: Figure 5 and Figure 6 As shown, it includes a furnace body 6 and a round light tube wafer heater of any embodiment of the present application. A furnace cavity 61 is arranged in the furnace body 6, and a furnace cover is arranged at the opening of the furnace cavity 61. The furnace cover is hinged on the furnace body 6 at one side of the opening of the furnace cavity 61, and can be opened and closed under the drive of a hydraulic cylinder. The round light tube wafer heater is arranged on the furnace cover, facing the opening of the furnace cavity 61.

[0063] A heat-conducting support ring 62 for supporting the wafer is arranged in the furnace chamber 61. The heat-conducting support ring 62 is usually made of SiC ring, but it can also be made of other heat-conducting materials that do not affect the silicon crystal structure in the wafer 7. The wafer 7 to be heated is placed on the heat-conducting support ring 62, which is concentrically arranged with the circularly arranged heating lamps 2 to ensure that the wafer 7 is located in the middle of the setting area of ​​the heating lamps 2 where the temperature uniformity is higher. The diameter of the heat-conducting support ring 62 is usually larger than the diameter of the wafer 7, but smaller than the diameter of the setting circle of the outermost heating lamps 2. Figure 2 As shown, the setting position of the wafer 7 on the heater seat 1 corresponds to the wafer range line 22, and the setting position of the thermal conductive support ring 62 on the heater seat 1 corresponds to the support ring range line 21. Both are located within the range of the setting circle of the outermost heating lamp tube 2 and are concentrically arranged with the setting circle of the outermost heating lamp tube 2.

[0064] A cooling unit 63 is provided at a certain distance below the bottom wall of the furnace chamber 61. The cooling unit 63 cools the outer side of the bottom wall of the furnace body 6 to ensure stable operation of the structure outside the bottom wall. An air inlet 64 for inputting process gas is provided on one side of the furnace chamber 61, and an air outlet 65 for discharging process gas is provided on the other side. By using process gas of different components, the lattice structure of the wafer 7 after heat treatment can be ensured, and the oxidation degree (thickness of the oxide layer) of the surface of the wafer 7 can be controlled.

[0065] The circular lamp wafer heater of the present application is fixed in the middle of the furnace cover, and a polygonal heater cover 13 is arranged on the outside of the heater seat 1, and a lamp power supply interface 14 is arranged on one side of the heater cover 13. The external heating power supply is introduced into the heater cover 13 through the lamp power supply interface 14, and connected to each heating lamp tube 2. The circulating water pipe of the cooling water circulation unit 11 is also arranged on the wall of one side of the heater cover 13, and the circulating cooling water is transported into the heater seat 1 to cool the outside of the heater seat 1.

[0066] When the wafer 7 is annealed, the wafer 7 is placed on the heat-conducting support ring 62 in the furnace chamber 61, so that the wafer 7 is away from the wall of the furnace chamber 61 and is located close to the area where the heating lamp tube 2 is set. A quartz window can also be provided between the heating lamp tube 2 and the wafer 7 to isolate the wafer in the furnace chamber 61 from the circular lamp tube wafer heater at the furnace chamber opening to prevent the heating of the circular lamp tube wafer heater from contaminating the wafer 7. The actual heating power of each heating lamp tube 2 is controlled by the lamp tube power distributor 4 to ensure the uniformity of the heating temperature of different parts of the wafer 7.

[0067] The pyrometer 3 is arranged on the furnace body 6 at the bottom wall of the furnace chamber 61, usually in the cooling unit 63 area, located at a position opposite to the middle area in the heat-conducting support ring 62. One end of the pyrometer 3 where the temperature sensing element is located passes through the bottom wall of the furnace chamber 61 and points to the wafer 7 placed on the heat-conducting support ring 62, so that the temperature detected by the pyrometer 3 can better represent the actual heating temperature of the wafer 7.

[0068] The wafer annealing furnace system of the present application can be used in semiconductor processes as processing equipment for rapid thermal processing, metal annealing after metal deposition, annealing for crystallization and defect removal after implantation, and RTO for thin oxidation.

[0069] An embodiment of the temperature control method of the wafer annealing furnace system of the present application is as follows: Figure 8 As shown, the following steps are included: S10, presetting the initial power ratio of each heating lamp tube 2 in the temperature control unit 41 of the lamp tube power distributor 4, wherein the power ratios set for different heating lamp tubes 2 can be the same or different. The power ratio control of different heating lamp tubes 2 is usually carried out in units of the power control element 42 that controls the actual heating power of the heating lamp tube 2. When multiple heating lamp tubes 2 are controlled by the same power control element 42, the power ratios of multiple heating lamp tubes 2 controlled by the same power control element 42 are the same; when each heating lamp tube 2 is controlled by a different power control element 42, the power ratio of each heating lamp tube 2 can be different, or the power ratios of several heating lamp tubes 2 that are close in position can be set to the same value. Specifically, the initial power ratio of the power ratio of each heating lamp tube 2 can be determined based on the previous adjustment value of the same type of circular lamp tube wafer heater combined with the debugging experience, and the setting value of the initial power ratio will not affect the actual temperature uniformity result of the circular lamp tube wafer heater after debugging.

[0070] S20. A calibration temperature sensor 81 and a plurality of debugging temperature sensors 82 are arranged within the range of the wafer 7 placement area in the furnace chamber 61, wherein the calibration temperature sensor 81 is arranged at a position opposite to the pyrometer 3, that is, the two measure the temperature value of the same position on the wafer; and the debugging temperature sensors 82 are dispersedly arranged at different positions around the calibration temperature sensor 81.

[0071] The specific number of debugging temperature sensors 82 to be set can be determined according to the size of the heated wafer 7 and the requirements for temperature uniformity. Generally, the higher the number of debugging temperature sensors 82, the better the temperature uniformity of the wafer 7 after debugging, but the more complicated the debugging process. Generally, for heating a 6-inch wafer, 1 calibration temperature sensor 81 and 4 debugging temperature sensors 82 can be set, a total of 5 temperature sensors; for heating an 8-inch wafer, 1 calibration temperature sensor 81 and 8 debugging temperature sensors 82 can be set, a total of 9 temperature sensors; for heating a 12-inch wafer, 1 calibration temperature sensor 81 and 8 or 16 debugging temperature sensors 82 can be set, a total of 9 or 17 temperature sensors.

[0072] When a specific wafer annealing furnace system for heating a 12-inch wafer 7 is used for temperature control, a calibration temperature sensor 81 and eight debugging temperature sensors 82 are provided. The projection positions of the nine temperature sensors and the pyrometer 3 on the circular lamp tube wafer heater are as follows: Figure 7 As shown, the nine temperature sensors are all arranged within the range corresponding to the wafer range line 22 , and the projection positions of the pyrometer 3 and the calibration temperature sensor 81 on the wafer heater overlap with each other.

[0073] S30, turn on the heating lamps 2, and use the initial power ratio to control the actual heating power of each corresponding heating lamp 2 to heat, so that the temperature in the furnace chamber 61 gradually increases. In each different temperature section during the temperature increase process, compare the difference between the detection value of the calibration temperature sensor 81 and the pyrometer 3. When there is a difference between the two, use the detection value of the calibration temperature sensor 81 to calibrate the detection value of the pyrometer.

[0074] In an actual heating process, the detection values ​​of the calibrated temperature sensor 81 and the pyrometer 3 at different temperatures are as follows: Fig. 9 As shown, in an ideal state, the temperature value detected by the pyrometer 3 (as shown on the horizontal axis) is the same as the temperature detected by the calibration temperature sensor 81 (as shown on the vertical axis), and the temperature comparison line is shown as the black line in the figure. In the actual heating process, in the stage of low heating temperature, the temperature value detected by the calibration temperature sensor 81 is lower than the temperature value detected by the pyrometer 3, and in the stage of high heating temperature, the temperature value detected by the calibration temperature sensor 81 is higher than the temperature value detected by the pyrometer 3, and the temperature comparison line is shown as the blue line. The temperature detected by the calibration temperature sensor 81 is used to correct and calibrate the temperature detected by the pyrometer 3.

[0075] S40, read the temperature corresponding to different parts of the wafer 7 detected by different debugging temperature sensors 82, and compare the temperature detected by each debugging temperature sensor 82 with the detection temperature of the calibrated pyrometer 3. If there is a difference between the two, it means that there is a difference between the actual heating temperature of the heating lamp tube 2 in the area and the required heating temperature, and this difference causes the temperature in different areas to be uneven. At this time, according to the positive and negative of the difference and the magnitude of the difference, combined with the inspection results of other adjacent debugging temperature sensors 82, adjust the power ratio of several heating lamp tubes 2 adjacent to the debugging temperature sensor 82, when the detection value of the debugging temperature sensor 82 is greater than the detection value of the pyrometer 3, reduce the actual heating power of the heating lamp tube 2; when the detection value of the debugging temperature sensor 82 is less than the detection value of the pyrometer 3, increase the actual heating power of the heating lamp tube 2, so that the temperature at each debugging temperature sensor 82 is close to the detection temperature of the pyrometer 3, so that the detection values ​​of the debugging temperature sensors 82 at different positions tend to be consistent, and improve the temperature uniformity of different debugging temperature sensors 82 positions.

[0076] S50, storing the adjusted power ratio of each heating lamp 2 at different temperature ranges of the pyrometer 3 in the temperature control unit 41, replacing the initial power ratio preset in the temperature control unit, and forming a power ratio database including the power ratio of each heating lamp 2 at different detection temperatures of the pyrometer 3.

[0077] S60, remove the calibration temperature sensor and the debugging temperature sensor in the furnace chamber 61, put the wafer 7 to be processed on the heat-conducting support ring 62 in the furnace chamber 61, control the heating power of each heating lamp 2 according to the power ratio value at different temperatures after debugging stored in the temperature control unit 41, and perform annealing operation on the wafer 7. In this way, there is no need to drive the wafer 7 and / or the heating lamp 2 to rotate, and only a pyrometer is used to detect the temperature in the furnace chamber 61, which can effectively ensure the uniformity of the heating temperature of different parts on the wafer 7.

[0078] In some embodiments of the temperature control method of the wafer annealing furnace system of the present application, in step S20, as Figure 2 As shown, 9 thermocouples are arranged on the test wafer 8, one of which is arranged in the middle of the test wafer 8, corresponding to the pyrometer 3, as a calibration temperature sensor 81; 8 thermocouples are arranged at different positions around the calibration temperature sensor 81, as debugging temperature sensors 82. By placing the test wafer 8 on the heat-conducting support ring 62 in the furnace chamber 61, a calibration temperature sensor 81 and multiple debugging temperature sensors 82 are arranged in the furnace chamber 61. Through this method, the equipment position and environment of each temperature sensor are consistent with the actual heating position and environment of the wafer 7, which can better ensure the uniformity of the temperature of different parts of the wafer 7 when the wafer 7 is heated.

[0079] In some embodiments of the temperature control method of the wafer annealing furnace system of the present application, in step S40, as Figure 4 As shown, an output generation module is provided in the temperature control unit 41, and the output generation module includes a PIDT parameter generator and a PIDT controller 412. The P, I, D, and T values ​​for controlling different heating lamps 2 around each debugging temperature sensor 82 are preset in the PIDT controller 412. During the heating process of the heating lamp 2, the debugging temperature detected by each debugging temperature sensor 82 and the temperature value detected by the pyrometer are input into the output generation module. The PIDT parameter generator adjusts the P, I, D, and T values ​​preset in the PIDT controller 412 according to the difference between the detection temperature of different debugging temperature sensors 82 and the detection temperature of the pyrometer, the position of different debugging temperature sensors 82, and the position of different heating lamps 2 around the debugging temperature sensor 82. The PIDT controller 412 can determine the adjustment direction and adjustment range of the power distribution of each heating lamp 2 according to the adjusted P, I, D, and T values ​​of each heating lamp 2, so that the power distribution ratio of a large number of heating lamps 2 around a small number of debugging temperature sensors 82 can be adjusted.

[0080] The PIDT controller 412 can also save the adjusted P, I, D, T values ​​to replace the original P, I, D, T preset values, so that the P, I, D, T values ​​used to adjust the power ratio of different heating lamps 2 are more accurate.

[0081] When the annealing temperature of wafer 7 is controlled by using a preferred embodiment of the temperature control method of the wafer annealing furnace system of the present application, the temperature curve required by the annealing process of wafer 7 is as follows: Fig.10 As shown by the blue line in the figure, the actual temperature curve of wafer 7 is as follows Fig.10 As shown by the red line in the figure, the temperatures of the two are highly consistent during the heating stage and the insulation stage. The power ratios of different heating lamps 2 during the heating process of wafer 7 from 550°C to 1050°C and during the insulation process at 1050°C are shown in Table 2 (only the power ratio values ​​of some heating lamps are shown).

[0082] Table 2 Power ratio of different heating lamps in different heating processes The output power in the heating stage is output according to the stored value in the power ratio database multiplied by 1.19.

[0083] During the heating process, the temperature values ​​detected by the five different debugging temperature sensors 82 are as follows: Fig.11 As shown. Among them, after adjustment using the temperature control method of the wafer annealing furnace system of the present application, in the preheating process before 550°C, the maximum difference of the detection values ​​of different debugging temperature sensors 82 is reduced from 40°C to less than 10°C; in the stage of heating from 550°C to 1050°C, the maximum difference of the detection values ​​of different debugging temperature sensors 82 is reduced from 30°C to less than 20°C; in the stage of keeping warm at 1050°C, the maximum difference of the detection values ​​of different debugging temperature sensors 82 is reduced from 10°C to less than 6°C, and the uniformity of the heating temperature is significantly improved.

[0084] When a preferred embodiment of the temperature control method of the wafer annealing furnace system of the present application is used to perform RTO processing of thin oxidation on a 12-inch wafer 7, the processing process is divided into several stages as shown in Table 3, wherein the PIDT controller 412 uses the PIDT parameter values ​​numbered as shown in Table 3 to adjust the power ratio of different heating lamps 2, wherein the values ​​of P, I, D, and T corresponding to the several PIDT parameter numbers involved are shown in Table 4. The adjusted temperature curve is shown in Fig.12 As shown by the red line on the top, it is close to the process requirement temperature curve shown by the white line, and the temperature control accuracy is higher, and the temperature deviation in the insulation stage is within ±1.0℃.

[0085] Table 3 PIDT control parameter number table at different stages of 1050℃RTO Table 4 Partial PIDT parameters in PIDT controller During the RTO process, Fig.13 As shown, before the processing temperature is adjusted using the temperature control method of the wafer annealing furnace system of the present application, by adjusting the temperature of the insulation stage (increasing by 3°C), the average thickness of the oxide layer on the surface of wafer 7 can be increased from 103.4A to 105.4A, which is closer to the thickness of 105A required by the process, but the difference in oxide layer thickness at different positions of wafer 7 changes from 3.71% of the thickness value to 3.72%, and the thickness of the oxide layer at different positions varies greatly. After adjustment using the method of the present application, the average thickness of the oxide layer of wafer 7 after processing is 106.5A, and the thickness difference at different positions is reduced to 1.88% of the thickness value. Further adjusting the temperature of the insulation stage (reducing by 2°C), the average thickness of the oxide layer on the surface of wafer 7 is reduced to 105.02A, which is closer to the thickness of 105A required by the process; the difference in oxide layer thickness at different positions of wafer 7 is also reduced to 1.82% of the thickness value, and the uniformity of the oxide layer thickness is higher.

[0086] like Fig.14 As shown, before using the temperature control method of the wafer annealing furnace system of the present application to adjust the heating temperatures of different heating lamps 2 of the wafer annealing furnace system, the total power consumption for processing 21 wafers 7 is shown in Figure (a), and the average total power consumption for processing each wafer 7 is 25672.59, with a repeatability of 0.51%; after adjustment using the method of the present application, the total power consumption for processing 21 wafers 7 is shown in Figure (b), and the average total power consumption for processing each wafer 7 is 25589.82, with a repeatability of 0.46%, indicating that the method of the present application has high repeatability.

[0087] In the description of the present application, the description with reference to the terms "one embodiment", "specific embodiment", "preferred embodiment", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0088] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A circular lamp tube wafer heater, characterized in that: The invention comprises a heater seat (1), a heating lamp tube (2), a pyrometer (3) and a lamp tube power distributor (4), wherein a plurality of the heating lamp tubes (2) are arranged on the heater seat (1) to form a plurality of mutually concentric circles, the pyrometer (3) is arranged corresponding to the middle of the area where the heating lamp tubes (2) are arranged, and the lamp tube power distributor (4) comprises a temperature control unit (41) and a plurality of power control elements (42), the plurality of the heating lamp tubes (2) are electrically connected to the plurality of power control elements (42) respectively, and the temperature control unit (41) is electrically connected to the pyrometer (3) and the plurality of power control elements (42) so as to be able to control the heating power of each heating lamp tube (2) respectively according to the detection result of the pyrometer (3).

2. The round lamp tube wafer heater according to claim 1, characterized in that: A metal reflector (5) is provided between the heating lamp tube (2) and the heater seat (1).

3. The round lamp tube wafer heater according to claim 2, characterized in that: A cooling water circulation unit (11) is provided between the heater seat (1) and the metal reflector (5), a cooling water temperature sensor (12) is provided on the heater seat (1), and both the cooling water circulation unit and the cooling water temperature sensor (12) are electrically connected to the temperature control unit (41).

4. The round lamp tube wafer heater according to claim 1, characterized in that: The pyrometer (3) is arranged on a side of a wafer (7) to be processed away from the heating lamp (2), and a focusing lens (31) is arranged between the wafer (7) and the pyrometer (3), with the focal point of the focusing lens (31) being located in a temperature sensing element area of ​​the pyrometer (3).

5. The round lamp tube wafer heater according to claim 1, characterized in that: The number of the heating lamp tubes (2) is the same as the number of the power control elements (42), and each of the heating lamp tubes (2) is connected to a different power control element (42) in a one-to-one correspondence.

6. The round lamp tube wafer heater according to claim 5, characterized in that: The temperature control unit (41) is provided with a power allocation storage element (411), and the power allocation storage element (411) stores the power ratio of each power control element (42) corresponding to different temperatures detected by the pyrometer (3). The temperature control unit (41) can call the power ratio value stored in the power allocation storage element (411) according to the temperature value detected by the pyrometer (3), so as to control the power ratio of each power control element (42).

7. A wafer annealing furnace system, characterized in that: The invention comprises a furnace body (6) and a circular lamp tube wafer heater according to any one of claims 1 to 6, wherein a furnace cavity (61) is arranged in the furnace body (6), the circular lamp tube wafer heater is arranged at the opening of the furnace cavity (61), a heat conductive support ring (62) for supporting a wafer is arranged in the furnace cavity (61), the heat conductive support ring (62) is arranged concentrically with the heating lamp tube (2), and the pyrometer (3) is arranged at the bottom of the furnace cavity (61) and is located in the middle area of ​​the heat conductive support ring (62).

8. A temperature control method for a wafer annealing furnace system according to claim 7, characterized in that: The steps include: S10, presetting the initial power ratio of each heating lamp tube (2) in the temperature control unit (41); S20, arranging a calibration temperature sensor (81) and a plurality of debugging temperature sensors (82) in the furnace chamber (61), wherein the calibration temperature sensor (81) is arranged opposite to the pyrometer (3), and the debugging temperature sensors (82) are dispersedly arranged at different positions around the calibration temperature sensor (81); S30, using the initial power ratio to control the actual heating power of each corresponding heating lamp (2) for heating, and using the calibration temperature sensor to calibrate the detection value of the pyrometer; S40, adjusting the power ratio of the adjacent heating lamp tubes (2) according to the difference between the temperature detected by the different debugging temperature sensors and the temperature value detected by the pyrometer (3), so that the detection values ​​of the different debugging temperature sensors tend to be consistent; S50, storing the power ratios of the pyrometer (3) and the heating lamps (2) at different temperatures in the temperature control unit (41), replacing the initial power ratios preset in the temperature control unit; S60, removing the calibration temperature sensor and the debugging temperature sensor, placing the wafer to be processed in the furnace chamber (61), controlling the heating power of each heating lamp tube (2) according to the power ratio at different temperatures stored in the temperature control unit (41), and performing annealing operation on the wafer to be processed.

9. The temperature control method of the wafer annealing furnace system according to claim 8, characterized in that: In step S20, a plurality of thermocouples are arranged on the test wafer (8), the test wafer (8) is placed in the furnace chamber (61), and one calibration temperature sensor (81) and a plurality of debugging temperature sensors (82) are arranged in the furnace chamber (61).

10. The temperature control method of the wafer annealing furnace system according to claim 8, characterized in that: In step S40, a PIDT controller (412) is provided in the temperature control unit (41), and the power ratio of the different tube heaters (2) adjacent to the debugging temperature sensor is adjusted using the P, I, D, and T values ​​stored in the PIDT controller (412), and the P, I, D, and T values ​​stored in the PIDT controller (412) are adjusted according to the difference between the adjusted temperature and the temperature detected by the pyrometer (3).

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