High-temperature phosphoric acid heater

Abstract

The invention discloses a high-temperature phosphoric acid heater in the field of semiconductor cleaning, which comprises a horizontally arranged metal fixing plate, a film coating heating disc coaxially arranged below the metal fixing plate and a quartz heat conducting disc with a limiting ring extending upwards, and the limiting ring hermetically wraps the film coating heating disc and the metal fixing plate. An air heat radiation layer is reserved between the coating heating disc and the quartz heat conduction disc, quartz damage caused by thermal expansion stress is avoided through non-contact heat transfer, and a liquid outlet hole is formed in the center of the quartz heat conduction disc and externally connected with a liquid inlet pipe. A nitrogen inlet and a nitrogen outlet pointing to the central area of the coating heating disc are symmetrically formed in the center of the metal fixing plate. The central heat accumulation area is actively cooled through nitrogen flow, and intrinsic safety, stress damage prevention and effective temperature control of the central area under the high-temperature working condition are achieved in cooperation with a radiation heat transfer and full-sealing structure.

Description

Technical Field

[0001] This invention relates to the field of semiconductor cleaning, and more specifically to a high-temperature phosphoric acid heater. Background Technology

[0002] In the semiconductor manufacturing process, the cleaning process is a core step to ensure device performance and yield. Phosphoric acid can significantly optimize the selectivity of etching rate under specific high temperature conditions.

[0003] However, existing semiconductor cleaning equipment heating technology still faces multiple limitations. In terms of safety, if the electrical connection points of traditional heaters are directly exposed to volatile organic liquids, they are highly susceptible to combustion and explosion accidents caused by electrical sparking.

[0004] In terms of structural reliability, the bonding heating method often generates huge thermal stress at high temperatures due to the difference in the expansion coefficients of the heating element and the quartz disk, which in turn leads to the crushing and breakage of the quartz disk.

[0005] In addition, since the heater is usually in a relatively closed working condition, and the process of the chemical liquid flowing from the center to the periphery is prone to heat accumulation in the central area of ​​the heater, the central temperature is much higher than that of the surrounding area. This risk of overheating in the central area, coupled with the limitations of traditional materials such as thermal conductive putty in terms of strict construction and low thermal conductivity, seriously affects the preheating efficiency of the cleaning fluid and the temperature uniformity of the wafer surface. Summary of the Invention

[0006] The purpose of this invention is to provide a high-temperature phosphoric acid heater to solve the problems of low heating efficiency, poor safety, and uneven temperature distribution caused by heat accumulation in the central region in semiconductor cleaning processes.

[0007] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution: A high-temperature phosphoric acid heater, comprising: The metal mounting plate is set horizontally. The coating heating plate is set coaxially below the metal fixing plate; A quartz heat-conducting plate is positioned coaxially below the coating heating plate; A limiting ring is formed coaxially at the outer edge of the quartz heat-conducting plate. The limiting ring extends upward to seal and cover the coated heating plate and the metal fixing plate. Among them, a preset distance is maintained between the coated heating plate and the quartz heat-conducting plate to form an air heat radiation layer; The quartz heat-conducting plate has a liquid outlet in the center area, which is connected to the external liquid supply system through an inlet pipe that passes through the coating heating plate and the metal fixing plate. The metal fixing plate has nitrogen inlets and outlets symmetrically distributed about the center of the circle. Both nitrogen inlets and outlets point to the center of the coating heating plate, so as to actively cool the central heat accumulation area of ​​the coating heating plate through the flow of nitrogen.

[0008] Furthermore, an annular groove is formed at the connection between the quartz heat-conducting plate and the inner side of the limiting ring. A nickel-chromium alloy heating wire is embedded in the annular groove. A PTFE protective ring is provided at the top opening of the annular groove to fix the nickel-chromium alloy heating wire in the annular groove.

[0009] Furthermore, the coated heating plate is made of microcrystalline glass, and its surface is printed with multiple independently temperature-controlled metal heat-conducting strips distributed in a concentric circle. All the metal heat-conducting strips divide the coated heating plate into multiple independent annular heating temperature zones radially.

[0010] Furthermore, a water-cooled heat dissipation plate is provided above the metal fixing plate in a coaxial state. A PTFE insulation layer is sandwiched between the water-cooled heat dissipation plate and the metal fixing plate. The metal fixing plate is fixed and suspended below the water-cooled heat dissipation plate by several isolation columns. The upper end of the limiting ring seals and covers the water-cooled heat dissipation plate and the PTFE insulation layer. The liquid inlet pipe passes through the PTFE insulation layer and the water-cooled heat dissipation plate in sequence upwards.

[0011] Furthermore, there are at least two liquid outlet holes, all of which are evenly distributed circumferentially, and sealing connections are provided at the penetration points of the liquid inlet pipe into the coating heating plate, the metal fixing plate, and the water-cooled heat dissipation plate.

[0012] Furthermore, the nickel-chromium alloy heating wire has an integrated first temperature sensor to detect the temperature of the nickel-chromium alloy heating wire in real time.

[0013] Furthermore, a second temperature sensor is installed at the joint of the PTFE protective ring to monitor whether the quartz heat-conducting plate is overheating.

[0014] Furthermore, the metal fixing plate, PTFE insulation layer, and water-cooled heat dissipation plate are all provided with connector through holes at the points where the wiring terminals of all metal heat-conducting strips protrude.

[0015] Furthermore, each annular heating zone is equipped with an independent temperature feedback module. The heater uses a PID control algorithm to adjust the output power of the corresponding metal heat-conducting strip in real time according to the measured plate temperature of each annular heating zone, so as to maintain the temperature difference on the surface of the quartz heat-conducting plate within ±0.5℃.

[0016] Furthermore, the water-cooled heat sink is fixedly mounted on a lifting gantry frame, which is used to move the heater in a vertical direction to adjust the distance between the quartz heat conduction plate and the wafer to be processed.

[0017] The beneficial effects of this invention are: This invention achieves physical isolation between the core heating component and the external volatile organic liquid environment by extending the limiting ring upward and sealing and covering the coated heating plate and the metal fixing plate, thereby eliminating the safety hazard caused by electrical sparking at the electrical connection point; This invention utilizes an air heat radiation layer formed by a preset gap between a coated heating plate and a quartz heat-conducting plate for non-contact heat transfer, eliminating the huge thermal stress caused by the difference in thermal expansion coefficients of different materials in traditional bonding heating, and preventing the quartz heat-conducting plate from being crushed and damaged in high-temperature working environments. This invention, in conjunction with a nitrogen inlet and outlet located in the central region of a metal fixing plate and pointing towards the central region of the coating heating plate, actively intervenes in the central heat accumulation phenomenon caused by the flow of liquid from the center outward under closed operating conditions through forced convection heat transfer. This effectively suppresses the overheating trend in the central region and ensures the uniformity of the thermal field on the wafer surface and the reliability of system operation under complex processes. Attached Figure Description

[0018] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0019] Figure 1 This is a top view schematic diagram of an embodiment of the present invention; Figure 2 This is a side view schematic diagram of an embodiment of the present invention; Figure 3 This is an exploded three-dimensional structural diagram of an embodiment of the present invention; Figure 4 This is a schematic diagram of the temperature zone distribution of the coating heating plate according to an embodiment of the present invention; The labels in the diagram represent the following: 1-Metal fixing plate; 2-Coated heating plate; 2a-Metal heat-conducting strip; 3-Quartz heat-conducting plate; 3a-Limiting ring; 4-Liquid inlet pipe; 5-Nitrogen inlet; 6-Nitrogen outlet; 7-Nichrome alloy heating wire; 8-PTFE protective ring; 9-Water-cooled heat sink; 9a-Connector through hole; 10-PTFE insulation layer; 11-Sealing connector. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] This embodiment provides a high-temperature phosphoric acid heater, designed to solve the problems of low heating efficiency, poor safety, and uneven temperature distribution caused by heat accumulation in the central region during semiconductor cleaning processes. For details, see [link to details]. Figures 1 to 3 The high-temperature phosphoric acid heater device includes a metal fixing plate 1, a coated heating plate 2, a quartz heat-conducting plate 3, and a limiting ring 3a.

[0022] The metal fixing plate 1 is set in a horizontal position; The coating heating plate 2 is arranged coaxially below the metal fixing plate 1; The quartz heat-conducting plate 3 is coaxially positioned below the coating heating plate 2; The limiting ring 3a is formed on the outer edge of the quartz heat conduction plate 3 in a coaxial state, and the limiting ring 3a extends upward to seal and cover the coated heating plate 2 and the metal fixing plate 1; A preset distance is maintained between the coated heating plate 2 and the quartz heat-conducting plate 3 to form an air heat radiation layer.

[0023] In terms of working principle, the coating heating plate 2 generates heat when energized, and the heat generated is transferred to the quartz heat-conducting plate 3 below through the air heat radiation layer in the form of heat radiation, thereby heating the wafer.

[0024] The use of non-contact radiative heat transfer can effectively prevent the risk of quartz disc breakage caused by the inconsistency in the expansion coefficients of the coated heating plate 2 and the quartz heat conduction plate 3. The limiting ring 3a completely covers the internal components, isolating the electrical connection points from external volatile liquids and improving the inherent safety of the equipment.

[0025] The quartz heat conduction plate 3 has a liquid outlet hole in the center area. The liquid outlet hole is connected to the external liquid supply system through the liquid inlet pipe 4 that passes through the coating heating plate 2 and the metal fixing plate 1. The liquid inlet pipe 4 passes through the coating heating plate 2 and the metal fixing plate 1 in sequence upwards. The metal fixing plate 1 has nitrogen inlet 5 and nitrogen outlet 6 symmetrically distributed about the center, and both nitrogen inlet 5 and nitrogen outlet 6 point towards the center of the coating heating plate 2.

[0026] Since the liquid flows from the center to the periphery and the heater is in a closed environment, heat accumulation is very likely to occur in the central area. By connecting to the nitrogen circulation system through nitrogen inlet 5 and nitrogen outlet 6, the flow of nitrogen is used to actively cool the heat accumulation area in the center of the coating heating plate 2, thereby meeting the process requirements for dynamic temperature regulation.

[0027] Because conventional heating structures suffer from heat loss at the edges, the wafer edge temperature drops, affecting process consistency. To address this edge effect, an annular groove is formed at the connection point between the quartz heat-conducting disk 3 and the inner side of the limiting ring 3a. A nickel-chromium alloy heating wire 7 is embedded in the annular groove, and a PTFE protective ring 8 is provided at the top opening of the annular groove. The PTFE protective ring 8 is used to fix the nickel-chromium alloy heating wire 7 in the annular groove. The nickel-chromium alloy heating wire 7 acts as an independent heating ring, directly providing thermal compensation to the outer ring of the quartz heat-conducting disk 3.

[0028] A single heating source is insufficient to achieve the extremely high temperature distribution on the wafer surface. Therefore, the coated heating plate 2 is made of microcrystalline glass, and its surface is printed with multiple independently temperature-controlled metal heat-conducting strips 2a distributed concentrically, such as... Figure 4 As shown, all the metal heat-conducting strips 2a divide the coated heating plate 2 into multiple independent annular heating temperature zones in the radial direction; Each annular heating zone is equipped with an independent temperature feedback module. The heater uses a PID control algorithm to adjust the output power of the corresponding metal heat-conducting strip 2a in real time according to the measured plate temperature of each annular heating zone, so as to maintain the temperature difference on the surface of the quartz heat-conducting plate 3 within ±0.5℃.

[0029] When the heater provides a high temperature above 150°C, if thermal isolation is not implemented, the upward dissipation of heat will damage external components. Therefore, a water-cooled heat sink 9 is provided above the metal fixing plate 1 in a coaxial position. A PTFE insulation layer 10 is sandwiched between the water-cooled heat sink 9 and the metal fixing plate 1. The metal fixing plate 1 is fixed and suspended below the water-cooled heat sink 9 by several isolation columns. The upper end of the limiting ring 3a seals and covers the water-cooled heat sink 9 and the PTFE insulation layer 10. The liquid inlet pipe 4 passes through the PTFE insulation layer 10 and the water-cooled heat sink 9 in sequence. The PTFE insulation layer 10 can isolate most of the air heat. Combined with the convective heat transfer of the water-cooled heat sink 9, it can effectively limit the upward conduction of heat.

[0030] To ensure the integrity and sealing of the multi-layered structure in the liquid transmission path, there are at least two liquid outlet holes. All liquid outlet holes are evenly distributed in the circumference. Sealing connectors 11 are provided at the penetration points of the liquid inlet pipe 4, the coating heating plate 2, the metal fixing plate 1, and the water cooling heat dissipation plate 9. Meanwhile, to meet the complex wiring requirements of multi-temperature zone control, the metal fixing plate 1, the PTFE insulation layer 10, and the water-cooled heat dissipation plate 9 are all provided with connector through holes 9a at the positions where the wiring terminals of all metal heat-conducting strips 2a pass through.

[0031] To monitor the status of high-load heat sources in real time, the nickel-chromium alloy heating wire 7 has an integrated first temperature sensor to detect the temperature of the nickel-chromium alloy heating wire 7 in real time. Based on this, in order to monitor the safety of the overall thermal field, a second temperature sensor is installed at the PTFE protection ring 8 joint to monitor whether the quartz heat conduction plate 3 is overheating. The second temperature sensor serves as a high temperature alarm and can trigger power-off protection when the temperature at the junction point is abnormal.

[0032] At the system integration level, in order to achieve precise positioning of the wafer, the water-cooled heat sink 9 is fixedly mounted on a lifting gantry frame. The lifting gantry frame is used to drive the heater to move in the vertical direction to adjust the distance between the quartz heat conduction plate 3 and the wafer to be processed, so that it can work stably inside the cleaning tower.

[0033] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. The scope of protection of the present invention is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within its spirit and scope of protection, and such modifications or equivalent substitutions should also be considered as falling within the scope of protection of the embodiments of the present invention.

Claims

1. A high-temperature phosphoric acid heater, characterized in that, include: The metal fixing plate (1) is set in a horizontal position; The coating heating plate (2) is arranged coaxially below the metal fixing plate (1); A quartz heat-conducting plate (3) is arranged coaxially below the coating heating plate (2); A limiting ring (3a) is formed on the outer edge of the quartz heat-conducting plate (3) in a coaxial state. The limiting ring (3a) extends upward to seal and cover the coated heating plate (2) and the metal fixing plate (1). The coated heating plate (2) and the quartz heat-conducting plate (3) maintain a preset distance to form an air heat radiation layer; The quartz heat-conducting plate (3) has a liquid outlet hole in its central area. The liquid outlet hole is connected to an external liquid supply system through a liquid inlet pipe (4) that passes through the coating heating plate (2) and the metal fixing plate (1). The metal fixing plate (1) has a nitrogen inlet (5) and a nitrogen outlet (6) symmetrically distributed about the center in its central area. Both the nitrogen inlet (5) and the nitrogen outlet (6) point to the central area of ​​the coating heating plate (2) so as to actively cool the central heat accumulation area of ​​the coating heating plate (2) through the flow of nitrogen.

2. A high-temperature phosphoric acid heater according to claim 1, characterized in that, The quartz heat-conducting plate (3) has an annular groove at the connection with the inner side of the limiting ring (3a). The annular groove is inlaid with a nickel-chromium alloy heating wire (7). A PTFE protective ring (8) is provided at the top opening of the annular groove. The PTFE protective ring (8) is used to fix the nickel-chromium alloy heating wire (7) in the annular groove.

3. A high-temperature phosphoric acid heater according to claim 1, characterized in that, The coated heating plate (2) is made of microcrystalline glass, and its surface is printed with multiple independently temperature-controlled metal heat-conducting strips (2a) distributed in a concentric circle. All the metal heat-conducting strips (2a) divide the coated heating plate (2) into multiple independent annular heating temperature zones in the radial direction.

4. A high-temperature phosphoric acid heater according to claim 1, characterized in that, A water-cooled heat sink (9) is provided above the metal fixing plate (1) in a coaxial state. A PTFE insulation layer (10) is sandwiched between the water-cooled heat sink (9) and the metal fixing plate (1). The metal fixing plate (1) is fixedly suspended below the water-cooled heat sink (9) by several isolation columns. The upper end of the limiting ring (3a) seals and covers the water-cooled heat sink (9) and the PTFE insulation layer (10). The liquid inlet pipe (4) passes through the PTFE insulation layer (10) and the water-cooled heat sink (9) in sequence.

5. A high-temperature phosphoric acid heater according to claim 4, characterized in that, The number of liquid outlet holes is at least two, and all the liquid outlet holes are evenly distributed circumferentially. Sealing connectors (11) are provided at the penetration points of the liquid inlet pipe (4) with the coating heating plate (2), the metal fixing plate (1) and the water cooling heat dissipation plate (9).

6. A high-temperature phosphoric acid heater according to claim 2, characterized in that, The nickel-chromium alloy heating wire (7) has a first temperature sensor integrated inside to detect the temperature of the nickel-chromium alloy heating wire (7) in real time.

7. A high-temperature phosphoric acid heater according to claim 6, characterized in that, A second temperature sensor is provided at the joint of the PTFE protective ring (8) to monitor whether the quartz heat-conducting plate (3) is overheating.

8. A high-temperature phosphoric acid heater according to claim 4, characterized in that, The metal fixing plate (1), the PTFE insulation layer (10) and the water-cooled heat dissipation plate (9) are provided with connector through holes (9a) at the positions where the wiring terminals of all the metal heat-conducting strips (2a) pass through.

9. A high-temperature phosphoric acid heater according to claim 1, characterized in that, Each of the aforementioned annular heating zones is equipped with an independent temperature feedback module. The heater adopts a PID control algorithm to adjust the output power of the corresponding metal heat-conducting strip (2a) in real time according to the measured plate temperature of each of the aforementioned annular heating zones, so as to maintain the temperature difference on the surface of the quartz heat-conducting plate (3) within the range of ±0.5℃.

10. A high-temperature phosphoric acid heater according to claim 1, characterized in that, The water-cooled heat dissipation plate (9) is fixedly mounted on a lifting gantry frame. The lifting gantry frame is used to drive the heater to move in the vertical direction in order to adjust the distance between the quartz heat conduction plate (3) and the wafer to be processed.

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