High-precision hot plate for wafer heating

Abstract

The utility model relates to a high-precision hot plate used for wafer heating. The hot plate comprises a substrate, a PID temperature adjusting module, a cooling module and a plurality of groups of thermocouple temperature sensors. A plurality of wafer supporting pins are arranged on one surface, facing a wafer, of the substrate, and an insulating layer is arranged on the other surface of the substrate. The PID temperature adjusting module is provided with a heating element and a power supply terminal used for supplying power to the heating element, the heating element is divided into three areas and arranged on the insulating layer, and the power supply terminal is arranged on the heating element. The multiple groups of thermocouple temperature sensors are used for measuring the temperature of each point of the hot plate, and are uniformly distributed from the center to the edge of the other surface of the substrate. And the PID temperature adjusting module is set to carry out regional adjustment on the temperature of the hot plate according to the temperature of each point of the hot plate detected by the thermocouple temperature sensor so as to reduce the temperature fluctuation of the hot plate, so that the temperature of the hot plate is uniform. And the cooling module is arranged on the substrate and is used for cooling the hot plate after the hot plate is heated.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductors, in particular to a high-precision hot plate for wafer heating, and in particular to a wafer heating plate suitable for forming semiconductor films on semiconductor wafers, liquid crystal substrates, circuit boards and the like. Background Art

[0002] Currently, the semiconductor integrated circuit (IC) industry has experienced exponential growth, with each generation of ICs having smaller and more complex circuits than the previous generation. In the process of IC development, functional density (i.e., the number of interconnected devices per chip area) has generally increased, while geometric size (i.e., the smallest component that can be produced using a manufacturing process) has decreased. In addition to IC components becoming smaller and more complex, the wafers used to manufacture ICs are also becoming smaller and smaller, and the requirements for wafer quality and yield are becoming higher and higher. The hot plate for baking wafers plays a vital role in the smooth progress of the entire lithography process. Hot plates are required in post-exposure baking, pre-baking, APCVD (atmospheric pressure chemical vapor deposition), PECVD (plasma vapor deposition), MOCVD (metal chemical vapor deposition) and other processes, and the fluctuation of the hot plate temperature is a key indicator affecting the wafer yield.

[0003] The existing hot plate only performs temperature feedback on the entire heating plate once, that is, the surface temperature of the wafer is only measured once to adjust the temperature of the heating element as a whole. Due to the structure of the hot plate, there is always airflow and contact between the outer cover and the substrate in the edge area of ​​the hot plate, which causes heat loss at the edge of the hot plate. Therefore, only adjusting the temperature of the hot plate as a whole once cannot improve the temperature fluctuation of the hot plate, which can easily lead to uneven temperature of the hot plate. Utility Model Content

[0004] The purpose of the utility model is to provide a high-precision hot plate for wafer heating, which can divide the hot plate into three areas for zone heating, accurately adjust the temperature of the hot plate in different areas to reduce the temperature fluctuation of the hot plate, ensure the uniform temperature of the hot plate, and improve the heating efficiency and yield rate of the wafer.

[0005] In order to achieve the above object, the utility model provides a high-precision hot plate for wafer heating, comprising:

[0006] A substrate, wherein a plurality of wafer supporting pins are arranged on one side of the substrate facing the wafer, and an insulating layer is arranged on the other side of the substrate;

[0007] A substrate, wherein a plurality of wafer supporting pins are arranged on one side of the substrate facing the wafer, and an insulating layer is arranged on the other side of the substrate;

[0008] A PID temperature adjustment module is provided with a heating element and a power supply terminal for supplying power to the heating element, the heating element is arranged on the insulating layer in three areas, and the power supply terminal is arranged on the heating element;

[0009] Multiple groups of thermocouple temperature sensors are used to measure the temperature of each point of the hot plate, and the multiple groups of thermocouple temperature sensors are evenly distributed from the center to the edge of the other side of the substrate. One group of thermocouple temperature sensors is composed of multiple thermocouple temperature sensors, and the multiple thermocouple temperature sensors in the same group are evenly distributed along the circumference of the substrate;

[0010] The PID temperature adjustment module is configured to perform regional adjustment on the temperature of the hot plate according to the temperature of each point of the hot plate detected by the thermocouple temperature sensor to reduce the temperature fluctuation of the hot plate so as to make the temperature of the hot plate uniform;

[0011] The cooling module is arranged on the substrate and is used to cool the hot plate after the hot plate is heated.

[0012] Optionally, the heating element is a resistance foil, and the three areas where the heating element is set include a first area, a second area and a third area. The resistance foil in each area is coiled on the insulating layer in a ring shape, and the PID temperature adjustment module is configured to control the temperature fluctuation of the hot plate to make the temperature of the hot plate uniform according to the width of the resistance foil in the three areas, the distance between the first area and the second area, the distance between the second area and the third area, the distance between the third area and the edge of the hot plate, the distance between the resistance foils in the first area, the distance between the resistance foils in the second area, and the distance between the resistance foils in the third area.

[0013] Optionally, at least two power supply terminals are provided on the resistance foil of each area, and the power supply terminals are connected to the resistance foil of the corresponding area by soldering to supply power, so as to adjust the current of the resistance foil of the corresponding area so that it heats the hot plate uniformly.

[0014] Optionally, the cooling module comprises:

[0015] A cooling cavity is arranged on the other side of the substrate and connected to the substrate by screws, and a cooling groove is provided in the cooling cavity;

[0016] A cooling pipe is arranged in the cooling tank. A solenoid valve is arranged on the cooling pipe. The solenoid valve is used to open after the heating of the hot plate is completed so that cold water flows into the cooling pipe to cool the hot plate.

[0017] Optionally, a plurality of avoidance grooves are provided in the cooling cavity, and the plurality of avoidance grooves correspond one-to-one to the plurality of power supply terminals. An elastic member is sleeved on the power supply terminal, and the elastic member cooperates with the avoidance grooves to protect the power supply terminal to ensure good contact between the power supply terminal and the heating element.

[0018] Optionally, the material of the substrate is a ceramic material, the thickness of the substrate is 2.8-3.2 mm, the thermal conductivity of the substrate is greater than 80 W / mK, and the color of the substrate is black.

[0019] Optionally, a plurality of interference holes are opened on a side of the substrate facing the wafer, and the plurality of interference holes correspond one-to-one to the plurality of wafer support pins. The wafer support pins are arranged in the corresponding interference holes by interference fit, and the height of the end of the wafer support pin protruding from the one side of the substrate is 0.05mm-0.5mm.

[0020] Optionally, the insulating layer is made of resin material, the thickness of the insulating layer is 0.3 mm-1 mm, and the withstand voltage of the insulating layer is greater than 1.5 KV.

[0021] Optionally, the temperature fluctuation of the hot plate after being heated to the target temperature is 0.7-0.9°C.

[0022] The beneficial effects of the utility model are as follows: the hot plate is divided into three areas for zone heating by the heating element, and the temperature of the hot plate is accurately adjusted in different areas according to the temperature of each point of the hot plate detected by the thermocouple temperature sensor to reduce the temperature fluctuation of the hot plate, ensure the uniform temperature of the hot plate, and improve the heating efficiency and yield rate of the wafer.

[0023] The above description is only an overview of the technical solution of the utility model. In order to more clearly understand the technical means of the utility model and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the utility model in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic structural diagram of a high-precision heat plate for wafer heating shown in an embodiment of the utility model;

[0025] Figure 2 This is a schematic structural exploded diagram of a high-precision heat plate for wafer heating shown in an embodiment of the utility model;

[0026] Figure 3 This is a schematic plan view of a high-precision heat plate for wafer heating according to an embodiment of the utility model;

[0027] Figure 4This is a schematic structural cross-sectional view of a high-precision heat plate for wafer heating shown in one embodiment of the utility model;

[0028] Figure 5 for Figure 4 A detailed enlarged view of the selected part;

[0029] Figure 6 This is a schematic distribution diagram of heating elements of a high-precision hot plate for wafer heating shown in one embodiment of the utility model;

[0030] Figure 7 This is a schematic plan view of a cooling module of a high-precision hot plate for wafer heating shown in one embodiment of the utility model;

[0031] In the figure: 1. substrate; 101. substrate; 102. insulation layer; 103. wafer support pin; 2. PID temperature adjustment module; 201. heating element; 202. power supply terminal; 203. elastic member; 3. cooling module; 301. cooling cavity; 302. cooling pipe; 303. cooling groove; 304. avoidance groove; 4. thermocouple temperature sensor. DETAILED DESCRIPTION

[0032] The technical solution of the utility model will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0033] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0034] In the description of the present utility model, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" 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 mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances. In addition, the technical features involved in the different embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other.

[0035] See also Figures 1 to 5 A high-precision hot plate for wafer heating shown in a preferred embodiment of the present application includes a substrate 1, a PID temperature adjustment module 2, a cooling module 3 and a plurality of groups of thermocouple temperature sensors. The substrate 1 (101) is provided with a plurality of wafer support pins 103 on one side facing the wafer, and an insulating layer 102 is provided on the other side of the substrate 101. The PID temperature adjustment module 2 is provided with a heating element 201 and a power supply terminal 202 for supplying power to the heating element 201. The heating element 201 is arranged on the insulating layer 102 in three areas, and the power supply terminal 202 is arranged on the heating element 201. The plurality of groups of thermocouple temperature sensors are used to measure the temperature of each point on the hot plate. The plurality of groups of thermocouple temperature sensors are evenly distributed from the center to the edge of the other side of the substrate 101. A group of thermocouple temperature sensors 4 is composed of a plurality of thermocouple temperature sensors 4, and the plurality of thermocouple temperature sensors 4 in the same group are evenly distributed along the circumference of the substrate 101. The PID temperature adjustment module 2 is configured to adjust the temperature of the hot plate in a region according to the temperature of each point of the hot plate detected by the thermocouple temperature sensor 4 to reduce the temperature fluctuation of the hot plate so that the temperature of the hot plate is uniform. The cooling module 3 is arranged on the substrate 101 and is used to cool the hot plate after the hot plate is heated.

[0036] According to the scheme of the embodiment of the utility model, the hot plate is divided into three areas for zone heating by the heating element 201, and the temperature of the hot plate is accurately adjusted according to the temperature of each point of the hot plate detected by the thermocouple temperature sensor 4 to reduce the temperature fluctuation of the hot plate, ensure the uniform temperature of the hot plate, and improve the heating efficiency and yield rate of the wafer. The hot plate can reach the target temperature of 180°C within 20s, and the temperature fluctuation at the target temperature is only 0.8°C.

[0037] The following is a detailed description with specific embodiments:

[0038] The hot plate in this embodiment is used to heat a 300 mm wafer.

[0039] See also Figure 6The heating element 201 is a resistance foil made of nickel-chromium alloy. The resistance foil is heated by the flow of electric current thereon. The three areas in which the heating element 201 is arranged include a first area, a second area and a third area. The resistance foil in each area is coiled on the insulating layer 102 in a ring shape. The PID temperature adjustment module 2 is arranged to reduce the temperature fluctuation of the hot plate to make the temperature of the hot plate uniform according to the settings of the widths W1, W2, and W3 of the resistance foil in the three areas, the distance S1 between the first area and the second area, the distance S2 between the second area and the third area, the distance S3 between the third area and the edge of the hot plate, the distance G1 between the resistance foils in the first area, the distance G2 between the resistance foils in the second area, and the distance G3 between the resistance foils in the third area.

[0040] The concept of temperature fluctuation is the difference between the highest temperature and the lowest temperature in a certain area. Taking into account the degree of temperature fluctuation control required by the hot plate in this embodiment and the cost reasons, dividing the hot plate into three areas for heating is the optimal solution under comprehensive cost and precision adjustment. After determining that the heating area of ​​the hot plate is three areas, in order to achieve the expected heating effect under the premise of the shortest length of the heating element 201, while being able to reduce costs and prevent the problem of uneven heating caused by overlapping multiple heat sources, the above-mentioned 9 key dimensions can be set to solve the above problems well. Obviously, the length and width of the resistor foil determine the size of its heating capacity. The larger the width and length of the resistor foil, the larger the area affected by the heating. Since the wafer and the hot plate are both circular, the arrangement of the heating element 201 is also circular, and its heating affected area is affected by the width and radius. Specifically, the value range of the width W of the resistor foil is between 1mm and 2mm. Regarding the setting of the distance G between the resistor foils in each area, its main function is to adjust the spacing between each area to improve the phenomenon of heat overlap of multiple heat sources between the resistor foils. Its value range is closely related to the width of the resistor foil, and the value range is between 5mm and 20mm. For the three-zone zoning, the temperature of each area is controlled by the resistor foil of each area separately, and the interval S between the areas is determined by two adjacent resistor foils. In this embodiment, the interval S between the areas is the sum of the heating influence ranges of the resistor foils in the two areas. For the 9 distance parameters contained in the three areas set by the heating element 201, they affect each other and are not fixed values. An optimal combination can be obtained through an optimization algorithm to control the temperature fluctuation of the hot plate. Specifically, for the optimization calculation of the 9 distance parameters, the structure of the entire hot plate is first simplified (where the heating element 201 is not simplified), and placed in the simulation software (comsol) for thermal analysis. The purpose of the thermal analysis is to obtain the temperature fluctuation under the hot plate structure. The simulation content is converted into the programming language of MATLAB, and the MOSO algorithm is used in the programming language to perform multi-objective optimization on the entire process. The input is the above-mentioned 9 distance parameters, and the output is the temperature fluctuation of the hot plate. By controlling the temperature fluctuation of the hot plate, the 9 distance parameters can be obtained.

[0041] See also Figure 3 At least two power supply terminals 202 are provided on the resistance foil of each area. The power supply terminals 202 are connected to the resistance foil of the corresponding area by soldering to supply power, and are used to adjust the current of the resistance foil of the corresponding area so that it can heat the hot plate evenly, and the temperature fluctuation of the hot plate can be controlled more accurately. Since the heating element 201 is a three-zone heating, after the temperature data of each point of the hot plate detected by the thermocouple temperature sensor 4 shows uneven temperature, the current size of each area can be adjusted by adjusting the power supply terminal 202 to adjust the temperature of each area so as to achieve uniform temperature of each point of the hot plate.

[0042] See also Figure 7 The cooling module 3 includes a cooling chamber 301 and a cooling pipe 302. The cooling chamber 301 is arranged on the other side of the substrate 101 and connected to the substrate 101 by screws. A cooling groove 303 is provided in the cooling chamber 301. The cooling pipe 302 is arranged in the cooling groove 303 through a hole provided at the bottom of the cooling chamber 301. A solenoid valve is provided on the cooling pipe 302. The solenoid valve is used to open after the heating of the hot plate is completed so that cold water flows into the cooling pipe 302 to cool the hot plate. After the thermocouple temperature sensor 4 detects that the temperature of the substrate 101 drops to room temperature, the solenoid valve is closed to stop supplying cooling water to the cooling pipe 302.

[0043] See also Figure 4 and Figure 7 The cooling cavity 301 is provided with a plurality of avoidance grooves 304, which correspond to the plurality of power supply terminals 202 one by one. The power supply terminals 202 are sleeved with elastic members 203, which cooperate with the avoidance grooves 304 to protect the power supply terminals 202 to ensure good contact between the power supply terminals 202 and the heating element 201. Even if the substrate 101 and the cooling cavity 301 expand due to the temperature difference during heating, the elasticity of the elastic member 203 can still make the power supply terminals 202 and the heating element 201 in line contact, so that the hot plate can fully respond to the dimensional changes caused by thermal cycles during use and handling.

[0044] Specifically, the material of the substrate 101 is a ceramic material including ceramic sintered materials such as silicon carbide, boron carbide, boron nitride, silicon nitride, aluminum oxide, and aluminum nitride. The thickness of the substrate 101 is 2.8-3.2 mm, and the thermal conductivity of the substrate 101 is greater than 80 W / mK to obtain effective heat diffusion. Since the heat transfer between the substrate 101 and the wafer is mainly through radiation heating, and semiconductors such as silicon absorb the most infrared rays with a wavelength of 8 um, in order to ensure the heat absorption rate, the ceramic color is selected as black, and the brightness is reduced to N3 or lower as the degree of blackening.

[0045] Specifically, see Figure 5, a plurality of interference holes are provided on the side of the substrate 101 facing the wafer, and the plurality of interference holes correspond to the plurality of wafer support pins 103 one by one, and the wafer support pins 103 are arranged in the corresponding interference holes through interference fit. The wafer support pins can control the distance between the wafer and the substrate 101, and the height of the end of the wafer support pins 103 protruding from the side of the substrate 101 is 0.05mm-0.5mm. When the height is lower than 0.05mm, the wafer warping will make the wafer contact with the substrate 101, and when the height is higher than 0.5mm, the heat transfer will be reduced, affecting the temperature response; the wafer support pins will compensate for the heat of thermal radiation during the heat transfer process, and the total heat obtained by the wafer is the sum of the thermal radiation of the substrate 101 and the heat conduction of the wafer support pins. In this embodiment, there are 6 interference holes and 9 thermocouple temperature sensors. Correspondingly, 9 corresponding holes for setting thermocouple temperature sensors are provided on the other side of the substrate 101.

[0046] The insulating layer 102 is made of resin material, has a thickness of 0.3 mm to 1 mm, and has a withstand voltage greater than 1.5 KV. When the thickness of the insulating layer 102 is less than 0.3 mm, the withstand voltage of the insulating layer 102 will be less than 1.5 KV, and its insulation cannot be maintained; and when the thickness of the insulating layer 102 exceeds 1 mm, when the insulating layer 102 is baked, the evaporation of the solvent and water increases, and bubbles are formed between the insulating layer 102 and the substrate 101, causing the substrate 101 to separate from the insulating layer 102, thereby inhibiting uniform heating of the substrate 101.

[0047] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0048] The above-mentioned embodiments only express several implementation methods of the utility model, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the utility model patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, which all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent shall be based on the attached claims.

Claims

1. A high-precision hot plate for wafer heating, characterized in that: include: A substrate, wherein a plurality of wafer supporting pins are arranged on one side of the substrate facing the wafer, and an insulating layer is arranged on the other side of the substrate; A PID temperature adjustment module is provided with a heating element and a power supply terminal for supplying power to the heating element, the heating element is arranged on the insulating layer in three areas, and the power supply terminal is arranged on the heating element; Multiple groups of thermocouple temperature sensors are used to measure the temperature of each point of the hot plate, and the multiple groups of thermocouple temperature sensors are evenly distributed from the center to the edge of the other side of the substrate. One group of thermocouple temperature sensors is composed of multiple thermocouple temperature sensors, and the multiple thermocouple temperature sensors in the same group are evenly distributed along the circumference of the substrate; The PID temperature adjustment module is configured to perform regional adjustment on the temperature of the hot plate according to the temperature of each point of the hot plate detected by the thermocouple temperature sensor to reduce the temperature fluctuation of the hot plate so as to make the temperature of the hot plate uniform; The cooling module is arranged on the substrate and is used to cool the hot plate after the hot plate is heated.

2. The high-precision hot plate for wafer heating according to claim 1, characterized in that: The heating element is a resistance foil. The three regions of the heating element include a first region, a second region and a third region. The resistance foil of each region is coiled on the insulating layer in a ring shape.

3. The high-precision hot plate for wafer heating according to claim 2, characterized in that: At least two power supply terminals are arranged on the resistance foil of each area, and the power supply terminals are connected to the resistance foil of the corresponding area by soldering to supply power, and are used to adjust the current of the resistance foil of the corresponding area so that it can evenly heat the hot plate.

4. The high-precision hot plate for wafer heating according to claim 1, characterized in that: The cooling module comprises: A cooling cavity is arranged on the other side of the substrate and connected to the substrate by screws, and a cooling groove is provided in the cooling cavity; A cooling pipe is arranged in the cooling tank. A solenoid valve is arranged on the cooling pipe. The solenoid valve is used to open after the heating of the hot plate is completed so that cold water flows into the cooling pipe to cool the hot plate.

5. The high-precision hot plate for wafer heating according to claim 4, characterized in that: A plurality of avoidance grooves are provided in the cooling cavity, and the plurality of avoidance grooves correspond one-to-one to the plurality of power supply terminals. An elastic member is sleeved on the power supply terminal, and the elastic member cooperates with the avoidance grooves to protect the power supply terminal to ensure good contact between the power supply terminal and the heating element.

6. The high-precision hot plate for wafer heating according to claim 1, characterized in that: The substrate is made of ceramic material, has a thickness of 2.8-3.2 mm, has a thermal conductivity greater than 80 W / mK, and has a black color.

7. The high-precision hot plate for wafer heating according to claim 6, characterized in that: The substrate is provided with a plurality of interference holes on one side facing the wafer, and the plurality of interference holes correspond one-to-one to the plurality of wafer support pins. The wafer support pins are arranged in the corresponding interference holes by interference fit, and the height of the end of the wafer support pin protruding from the one side of the substrate is 0.05mm-0.5mm.

8. The high-precision hot plate for wafer heating according to claim 1, characterized in that: The insulating layer is made of resin material, the thickness of the insulating layer is 0.3 mm-1 mm, and the withstand voltage of the insulating layer is greater than 1.5 KV.

9. The high-precision hot plate for wafer heating according to claim 1, characterized in that: The temperature fluctuation of the hot plate after being heated to the target temperature is 0.7-0.9°C.

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