Electrostatic chuck backside cooling gas overcharge prevention device and electrostatic chuck

Abstract

The application provides an electrostatic chuck back cooling gas anti-overcharge device and an electrostatic chuck. A gas adjusting module can realize total flow adjustment of cooling gas. A gas buffer module includes one or two gas buffer units. The gas buffer unit includes a flow limiting channel and a gravity flow limiting piece. The flow limiting channel is vertically arranged on the cooling gas channel. The gravity flow limiting piece is movably arranged in the flow limiting channel. When the cooling gas flows through the flow limiting channel, the gravity flow limiting piece is displaced under the combined action of its own gravity and the thrust of the cooling gas, so as to limit the flow of the cooling gas and inhibit the initial pressure overshoot. A pressure detection and regulation module collects the real-time gas pressure in the cooling gas channel on the side close to the electrostatic chuck downstream of the gas buffer module, forms a closed loop control, and dynamically drives the gas adjusting module to adjust the gas flow.

Description

Technical Field

[0001] This invention relates to the field of semiconductor equipment technology, and in particular to an anti-overcharge device for the back cooling gas of an electrostatic chuck and an electrostatic chuck. Background Technology

[0002] In semiconductor manufacturing, electrostatic chucks (ESCs) are core equipment in processes such as etching and deposition, using an electrostatic field to hold and hold the wafer. Because the wafer generates a significant amount of heat during the process, it needs to be cooled by a back-side cooling gas (such as helium). This back-side cooling gas enters the gap between the wafer and the ESC through microchannels on the surface of the ESC or through vents on the back of the wafer, forming a gas layer that facilitates heat conduction.

[0003] In existing technologies, back-side cooling gas is typically introduced directly into the air guide cavity of the electrostatic chuck through an air channel. However, during the initial stage of back-side cooling gas supply, sudden pressure changes within the air channel can easily lead to back-side cooling gas pressure overshoot. This overshoot pressure can cause uneven stress on the wafer, affecting wafer pick-up accuracy and even causing the wafer to be blown away, reducing processing yield. To address this issue, existing solutions typically employ multiple flow-limiting orifices in the air path. The principle is to use small orifices to limit the maximum instantaneous gas flow rate, thereby suppressing pressure overshoot. However, this solution has significant drawbacks: The current-limiting gasket is easily damaged: Frequent pressure impacts can cause plastic deformation of the current-limiting gasket, change the aperture, and reduce the over-pressure prevention effect after long-term use; Response speed and stability are contradictory: relying solely on flow-limiting gaskets results in a slow system response speed, making it difficult to adapt to the dynamic balance requirements of gas pressure during rapid switching of process steps, leading to long pressure regulation time and affecting process efficiency.

[0004] Therefore, it is necessary to provide a novel anti-overcharge device for the back-side cooling gas of an electrostatic chuck and an electrostatic chuck to solve the above-mentioned problems existing in the prior art. Summary of the Invention

[0005] The purpose of this invention is to provide an anti-overcharge device for the cooling gas on the back of an electrostatic chuck and an electrostatic chuck, so as to solve the above-mentioned technical problems.

[0006] To achieve the above objectives, the electrostatic chuck back-side cooling gas overcharge prevention device of the present invention includes: A gas regulation module is installed in the cooling gas channel that is connected to the air guide cavity of the electrostatic chuck, and is used to regulate the total flow rate of cooling gas delivered by the cooling gas channel. A gas buffer module includes one or two gas buffer units. Each gas buffer unit includes a flow-limiting channel and a gravity flow-limiting component. The flow-limiting channel is vertically arranged and disposed on the cooling gas passage. The gravity flow-limiting component is movably disposed within the flow-limiting channel. When the cooling gas flows through the flow-limiting channel, the gravity flow-limiting component is displaced under the combined action of its own gravity and the thrust of the cooling gas, thereby limiting the flow of the cooling gas. The pressure detection and control module is electrically connected to the gas regulation module. It is used to detect the gas pressure in the cooling gas passage between the gas buffer module and the gas guide chamber, and drive the gas regulation module to adjust the total flow rate of the cooling gas according to the gas pressure.

[0007] Optionally, the gas buffer unit further includes a buffer cavity, which is disposed between the flow-limiting channel and the cooling gas channel, for buffering and depressurizing the cooling gas entering the buffer cavity.

[0008] Optionally, a buffer cavity is provided in the buffer cavity, the cross-sectional area of ​​the buffer cavity is larger than the cross-sectional area of ​​the flow-limiting channel, and the cross-sections of the buffer cavity and the flow-limiting channel are both perpendicular to the flow direction of the cooling gas in the flow-limiting channel.

[0009] Optionally, the gravity flow restrictor is spherical.

[0010] Optionally, a spiral air passage is formed on the inner wall of the flow-limiting channel.

[0011] Optionally, the gas regulation module includes a first flow regulation unit and a second flow regulation unit electrically connected to the pressure detection and regulation module. The first flow regulation unit and the second flow regulation unit are arranged in parallel on the cooling gas passage to jointly regulate the flow rate of the cooling gas in the cooling gas passage. In the initial stage of gas supply, the flow rate of the first flow regulating unit is the first flow rate, and the flow rate of the second flow regulating unit is the second flow rate. The first flow rate is greater than the second flow rate. The downstream of the gas buffer module is determined along the flow direction of the cooling gas. When the pressure detection and control module detects that the gas pressure in the cooling gas passage downstream of the gas buffer module is greater than or equal to a preset pressure threshold, the pressure detection and control module drives the first flow regulating unit to shut down.

[0012] Optionally, the anti-overcharge device for the cooling gas on the back of the electrostatic chuck further includes a gas storage module. The gas storage module is disposed on the cooling gas channel, and the downstream of the gas storage module is determined along the flow direction of the cooling gas. When the internal pressure of the cooling gas channel downstream of the gas storage module is lower than a preset pressure replenishment threshold, the gas storage module replenishes the pressure of the cooling gas channel.

[0013] Optionally, the gas storage module includes a gas storage tank, an inlet check valve, and an outlet check valve. The gas storage tank is an adjustable-volume gas storage structure. The gas storage tank has an inlet and an outlet, both of which are connected to the cooling air passage. The inlet check valve is located on the inlet and allows cooling gas to flow from the cooling air passage to the gas storage tank while preventing cooling gas from flowing from the gas storage tank to the cooling air passage. The outlet check valve is located on the outlet and allows cooling gas to flow from the gas storage tank to the cooling air passage while preventing cooling gas from flowing from the cooling air passage to the gas storage tank. Specifically, when the gas pressure in the cooling air passage is greater than a preset storage pressure threshold, the inlet check valve opens; when the gas pressure in the cooling air passage is lower than a preset pressure replenishment threshold, the outlet check valve opens.

[0014] Optionally, the anti-overcharge device for the cooling gas on the back of the electrostatic chuck further includes a recovery module, which is connected to the cooling gas duct and is used to recover the residual gas in the cooling gas duct and / or the gas guide cavity at the end of the process.

[0015] The present invention also provides an electrostatic chuck, comprising a chuck body and an anti-overcharge device for cooling gas on the back of the electrostatic chuck as described in any one of the present inventions. The chuck body has a plurality of air guiding chambers, and the adsorption surface of the chuck body has a plurality of cooling air holes, which are connected to the air guiding chambers.

[0016] The beneficial effects of this invention are as follows: the gas regulating module can regulate the total flow rate of the cooling gas; the gas buffer module includes one or two gas buffer units, each gas buffer unit including a flow limiting channel and a gravity flow limiting element. The flow limiting channel is vertically arranged and located on the cooling gas passage. The gravity flow limiting element is movably arranged within the flow limiting channel. When the cooling gas flows through the flow limiting channel, the gravity flow limiting element is displaced under the combined action of its own gravity and the thrust of the cooling gas, thereby limiting the flow of the cooling gas; the pressure detection and control module collects the real-time gas pressure in the cooling gas passage downstream of the gas buffer module near the electrostatic chuck, forming a closed-loop control, and dynamically driving the gas regulating module to adjust the gas supply flow rate. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overcharge prevention device for the cooling gas on the back of the electrostatic chuck in some embodiments of the present invention; Figure 2 This is a schematic diagram of the overcharge prevention device for the cooling gas on the back of the electrostatic chuck in some embodiments of the present invention; Figure 3 This is a schematic diagram of the structure of a gas buffer unit in some embodiments of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed following the word and its equivalents, but do not exclude other elements or objects.

[0019] To address the problems existing in the prior art, embodiments of the present invention provide an overcharge prevention device for the cooling gas on the back of an electrostatic chuck. (Refer to...) Figure 1 and Figure 2 The anti-overcharge device for the cooling gas on the back of the electrostatic chuck includes a gas regulation module 100, a gas buffer module 200, and a pressure detection and control module.

[0020] Reference Figure 1 , Figure 2 and Figure 3 The gas regulating module 100 is disposed in the cooling air passage connected to the air guide cavity of the electrostatic chuck, and is used to regulate the total flow rate of cooling gas transported by the cooling air passage. The gas buffer module 200 includes one or two gas buffer units. The gas buffer unit includes a flow limiting channel 201 and a gravity flow limiting element 202. The flow limiting channel 201 is vertically arranged and disposed on the cooling air passage. The gravity flow limiting element 202 is movably disposed within the flow limiting channel 201. When the cooling gas flows through the flow limiting channel 201, the gravity flow limiting element 202 is displaced under the combined action of its own gravity and the thrust of the cooling gas, so as to limit the flow of the cooling gas. The pressure detection and control module is electrically connected to the gas regulating module 100, and is used to detect the gas pressure in the cooling air passage between the gas buffer module 200 and the air guide cavity, and drive the gas regulating module 100 to adjust the total flow rate of the cooling gas according to the gas pressure.

[0021] In this application, the gas regulating module can regulate the total flow rate of the cooling gas; the gas buffer module includes one or two gas buffer units, each including a flow limiting channel and a gravity flow limiting element. The flow limiting channel is vertically arranged and located on the cooling gas passage. The gravity flow limiting element is movably arranged within the flow limiting channel. When the cooling gas flows through the flow limiting channel, the gravity flow limiting element is displaced under the combined action of its own gravity and the thrust of the cooling gas to limit the flow of the cooling gas and suppress pressure overshoot in the initial gas supply. The pressure detection and control module collects the real-time gas pressure in the cooling gas passage downstream of the gas buffer module near the electrostatic chuck, forming a closed-loop control and dynamically driving the gas regulating module to adjust the gas supply flow rate.

[0022] This application abandons the single fixed aperture current limiting method, thus avoiding the problems of long-term pressure deformation and rapid performance degradation of the current limiting gasket. At the same time, it combines closed-loop pressure regulation and passive overpressure protection (i.e., current limiting by the gas buffer module), taking into account both the adjustment response speed and pressure stability. It can effectively suppress the pressure surge at the moment of cooling gas introduction, avoid uneven stress on the wafer and being blown away from the electrostatic chuck by the airflow, ensure the stability of the wafer adsorption state, improve the uniformity of the gas layer on the back of the wafer, reduce wafer temperature differences, and improve the semiconductor process yield. Furthermore, it can adapt to the scenario of rapid switching of process steps, shorten the pressure stabilization time, and improve the process efficiency of the equipment and the long-term reliability of the gas path.

[0023] In some embodiments, reference is made to Figure 1 The cooling air duct includes a first sub-cooling air duct 301, a first parallel cooling air duct 302, and a second parallel cooling air duct 303. One end of the first sub-cooling air duct 301 is connected to a cooling air source. One end of the first parallel cooling air duct 302 and one end of the second parallel cooling air duct 303 are both connected to the other end of the first sub-cooling air duct 301. The other ends of the first parallel cooling air duct 302 and the second parallel cooling air duct 303 are both connected to the air guide cavity 300 of the electrostatic chuck.

[0024] In some other embodiments, reference is made to Figure 2 The cooling air duct further includes a first sub-cooling air duct 301, a second sub-cooling air duct 304, a first parallel cooling air duct 302, and a second parallel cooling air duct 303. One end of the first sub-cooling air duct 301 is connected to a cooling air source. One end of the first parallel cooling air duct 302 and one end of the second parallel cooling air duct 303 are both connected to the other end of the first sub-cooling air duct 301. The other end of the first parallel cooling air duct 302 and the other end of the second parallel cooling air duct 303 are both connected to one end of the second sub-cooling air duct 304. The other end of the second sub-cooling air duct 304 is connected to the air guide cavity 300 of the electrostatic chuck.

[0025] In some embodiments, reference is made to Figure 1 and Figure 2 The gas regulation module 100 includes a first flow regulation unit 101 and a second flow regulation unit 102. The first flow regulation unit 101 and the second flow regulation unit 102 are connected in parallel on the cooling air passage (i.e., the first flow regulation unit 101 is located on the first parallel cooling air passage 302, and the second flow regulation unit 102 is located on the second parallel cooling air passage 303), jointly regulating the flow rate of the cooling gas in the cooling air passage. Specifically, at the initial stage of gas supply, the flow rate of the first flow regulation unit 101 is the first flow rate, and the flow rate of the second flow regulation unit 102 is the second flow rate. The first flow rate is greater than the second flow rate. The downstream of the gas buffer module is determined along the flow direction of the cooling gas. When the pressure detection and control module detects that the gas pressure in the cooling air passage downstream of the gas buffer module is greater than or equal to a preset pressure threshold, the pressure detection and control module drives the first flow regulation unit 101 to shut off.

[0026] The first flow regulating unit and the second flow regulating unit are arranged in parallel in the cooling air duct. At the beginning of the gas supply, the first flow regulating unit provides a larger first flow rate and the second flow regulating unit provides a smaller second flow rate. By relying on the two-way gas supply, the basic gas pressure of the cooling air duct can be quickly established, shortening the pressure build-up time. When the pressure detection and control module detects that the pressure in the cooling air duct downstream of the gas buffer module reaches the preset pressure threshold, it promptly controls the first flow regulating unit to shut down, leaving only the second flow regulating unit to continue supplying gas.

[0027] The segmented gas supply strategy, which involves rapid pressure build-up with a high flow rate followed by steady-state pressure stabilization with a low flow rate, effectively suppresses pressure overshoot during the initial cooling gas introduction. This prevents uneven wafer stress and displacement caused by instantaneous high-pressure impacts. Simultaneously, it balances pressure build-up speed and steady-state control accuracy, shortening process latency and maintaining a stable cooling gas layer on the back of the wafer to ensure wafer temperature uniformity and improve process yield. The parallel dual-flow unit (first and second flow regulation units) for graded control offers simple and reliable control logic, making it easier to balance pressure build-up rate and overshoot prevention requirements compared to a single flow regulation valve.

[0028] In some embodiments, flow-limiting gaskets may also be provided in the first sub-cooling air passage, the second sub-cooling air passage, the first parallel cooling air passage, and the second parallel cooling air passage. The orifice diameter of the flow-limiting gasket is 0.1 mm to 0.5 mm. Specifically, the orifice diameter of the flow-limiting gasket is 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, or 0.5 mm, or any value between any two of the aforementioned values.

[0029] In some embodiments, the cooling gas is helium or nitrogen, and the inner walls of the first sub-cooling gas channel, the second sub-cooling gas channel, the first parallel cooling gas channel, and the second parallel cooling gas channel are all coated with a ceramic coating. The low permeability of the ceramic coating can prevent helium and nitrogen leakage.

[0030] Reference Figure 1 The gas buffer module 200 includes two gas buffer units, which are respectively disposed on the first parallel cooling air passage 302 and the second parallel cooling air passage 303.

[0031] Reference Figure 2 The gas buffer module 200 includes a gas buffer unit, which is disposed on the second sub-cooling air passage 304.

[0032] Reference Figure 3 The gas buffer unit further includes a buffer cavity 203, which is disposed between the flow limiting channel 201 and the cooling gas channel, and is used to buffer and reduce the pressure of the cooling gas entering the buffer cavity 203.

[0033] Reference Figure 3 The buffer cavity 203 is provided with a buffer cavity 2031. The cross-sectional area of ​​the buffer cavity 2031 is larger than the cross-sectional area of ​​the flow-limiting channel 201. The cross-sections of the buffer cavity 2031 and the flow-limiting channel 201 are both perpendicular to the flow direction of the cooling gas in the flow-limiting channel 201.

[0034] In some embodiments, the volume of the buffer chamber is the product of the target cooling gas flow rate and time, where the time is between 1s and 5s. Specifically, the time is 1s, 2s, 3s, 4s, or 5s, or any value between any two of the aforementioned times.

[0035] Reference Figure 3 The gravity flow restrictor 202 is spherical.

[0036] Reference Figure 3 A spiral air passage 2011 is provided on the inner wall of the flow restriction channel 201.

[0037] In some embodiments, the inner diameter of the flow-limiting channel decreases continuously from the air inlet to the air outlet.

[0038] In some embodiments, the diameters at both ends of the flow-limiting channel are reduced, or a limiting structure is provided to prevent the gravity flow-limiting element from entering the buffer cavity or the cooling air passage.

[0039] In some embodiments, the buffer cavity and the flow-limiting channel are connected in series on the cooling air passage and are positioned upstream and downstream along the flow direction of the cooling gas, with the flow-limiting channel located downstream of the buffer cavity.

[0040] In some embodiments, the cooling gas is helium or nitrogen, and the inner wall of the buffer chamber and the inner wall of the flow-limiting channel are coated with a ceramic coating. The low permeability of the ceramic coating can prevent helium and nitrogen leakage.

[0041] In some embodiments, the anti-overcharge device for the cooling gas on the back of the electrostatic chuck further includes a gas storage module. The gas storage module is disposed on the cooling gas channel, and the downstream of the gas storage module is determined along the flow direction of the cooling gas. When the internal pressure of the cooling gas channel downstream of the gas storage module is lower than a preset pressure replenishment threshold, the gas storage module replenishes the pressure of the cooling gas channel.

[0042] The gas storage module is positioned on the cooling gas duct and can pre-store a certain pressure of cooling gas. When the pressure in the downstream gas duct of the gas storage module falls below a preset pressure replenishment threshold, the gas storage module can promptly release the stored gas into the cooling gas duct to replenish the pressure. During process switching or airflow fluctuations that cause a drop in downstream pressure, it quickly compensates for the gas volume, suppresses downward fluctuations in the supply pressure, and prevents the cooling gas pressure supplied to the electrostatic chuck from being too low. Working in conjunction with the overpressure relief function of the front-end gas buffer module, it forms a two-way pressure regulation mechanism of high-pressure relief and low-pressure replenishment, stabilizing the cooling gas pressure within the process-allowed range. This ensures the continuous stability of the cooling gas layer on the back of the wafer, reduces wafer temperature fluctuations, and improves semiconductor process consistency and processing yield.

[0043] In some embodiments, the gas storage module includes a gas storage tank, an inlet check valve, and an outlet check valve. The gas storage tank is an adjustable-volume gas storage structure with an inlet and an outlet. Both the inlet and outlet are connected to the cooling air passage. The inlet check valve is located at the inlet and allows cooling gas to flow from the cooling air passage to the gas storage tank while preventing cooling gas from flowing from the gas storage tank to the cooling air passage. The outlet check valve is located at the outlet and allows cooling gas to flow from the gas storage tank to the cooling air passage while preventing cooling gas from flowing from the cooling air passage to the gas storage tank.

[0044] In some embodiments, the inlet check valve opens when the gas pressure in the cooling air passage is greater than a preset storage pressure threshold, and the outlet check valve opens when the gas pressure in the cooling air passage is lower than a preset pressure replenishment threshold.

[0045] In some embodiments, the gas storage tank is a flexible tank. The gas storage module also includes a volume limiting member, such as a cover, which covers the outside of the gas storage tank to limit the volume of the gas storage tank.

[0046] In some embodiments, the gas storage tank is a rigid tank with a cylindrical inner cavity. A circular baffle is provided inside the cylindrical inner cavity, and the edge of the baffle is slidably and sealingly connected to the inner wall of the gas storage tank. The circular baffle is driven by a motor to slide along the longitudinal direction of the cylindrical inner cavity to achieve volume adjustment.

[0047] In some embodiments, when the cooling air passage does not include a second sub-cooling air passage, the gas storage module is disposed on the first parallel cooling air passage and downstream of the first flow regulating unit along the delivery direction of the cooling gas.

[0048] In some embodiments, when the cooling air passage includes a second sub-cooling air passage, the air storage module is disposed on the second sub-cooling air passage.

[0049] In some embodiments, a flow-limiting gasket can also be provided in the cooling air duct downstream of the gas storage module. The orifice diameter of the flow-limiting gasket is 0.1mm-0.5mm. Through the flow-limiting and overcharge prevention function of the gas buffer module, the impact of the cooling gas on the flow-limiting gasket is reduced, which can greatly avoid deformation and damage to the flow-limiting gasket. Furthermore, the flow-limiting gasket can also limit the flow, further enhancing the overcharge prevention effect. Specifically, the orifice diameter of the flow-limiting gasket is 0.1mm, 0.2mm, 0.3mm, 0.4mm, or 0.5mm, or any value between any two of the aforementioned values.

[0050] In some embodiments, both the first flow regulation unit and the second flow regulation unit are mass flow controllers (MFC).

[0051] In some embodiments, the pressure detection and control module includes a pressure sensor and a processing unit. The pressure sensor is electrically connected to the processing unit and is embedded in the inner wall of the second sub-cooling air passage or the inner wall of the second parallel cooling air passage. The processing unit is a central processing unit (CPU) or a microcontroller unit (MCU).

[0052] In some embodiments, the processing unit pre-stores a pressure-parameter relationship model. Based on this model, the processing unit drives the first and second flow regulation units to adjust the total flow rate of the cooling gas according to the gas pressure detected by the pressure sensor. The pressure-parameter relationship model can be obtained through simulation or by acquiring and fitting multiple sets of data.

[0053] In some embodiments, the anti-overcharge device for the cooling gas on the back of the electrostatic chuck further includes a recovery module connected to the cooling gas duct, which is used to recover the residual gas in the cooling gas duct and / or the gas guide cavity at the end of the process to avoid pollution caused by the residual gas.

[0054] In some embodiments, the recovery module includes an exhaust gas recovery valve, an exhaust gas pipeline, a vacuum pump, and an exhaust gas storage tank. One end of the exhaust gas pipeline is connected to the cooling air duct (for example, one end of the exhaust gas pipeline is connected to the second sub-cooling air duct), and the other end of the exhaust gas pipeline is connected to the exhaust gas storage tank. The exhaust gas recovery valve and the vacuum pump are both mounted on the exhaust gas pipeline. After the process is completed, both the exhaust gas recovery valve and the vacuum pump are opened to pump the residual gas in the cooling air duct and / or the air guide chamber into the exhaust gas storage tank.

[0055] The present invention also provides an electrostatic chuck, including a chuck body and an anti-overcharge device for cooling gas on the back of the electrostatic chuck. The chuck body has a plurality of air guiding chambers, and the adsorption surface of the chuck body has a plurality of cooling air holes, which are connected to the air guiding chambers.

[0056] In some embodiments, the plurality of air guiding cavities are divided into annular groove air guiding cavities and a plurality of radial groove air guiding cavities. The plurality of annular groove air guiding cavities are arranged in concentric rings with the center of the electrostatic chuck as the center, and the plurality of radial groove air guiding cavities are arranged between the annular groove air guiding cavities to connect two adjacent annular groove air guiding cavities.

[0057] In some embodiments, the diameter of the cooling vent is 0.5mm-0.6mm. Specifically, the diameter of the cooling vent is 0.5mm, 0.525mm, 0.55mm, 0.575mm, or 0.6mm, or any value between any two of the aforementioned diameters.

[0058] In some embodiments, the width of the annular groove air guide cavity is 0.2mm-0.6mm. Specifically, the width of the annular groove air guide cavity is 0.2mm, 0.3mm, 0.4mm, 0.5mm or 0.6mm, or any value between any two of the aforementioned widths.

[0059] In some embodiments, the depth of the annular groove air guide cavity is 0.1mm-0.2mm. Specifically, the depth of the annular groove air guide cavity is 0.1mm, 0.15mm, or 0.2mm, or any value between any two of the aforementioned depths.

[0060] In some embodiments, the distance between the outer edge of the maximum diameter annular groove air guide cavity and the outer edge of the electrostatic chuck is greater than 2 mm.

[0061] In some embodiments, the anti-overcharge device for the back cooling gas of the electrostatic chuck includes a pre-process start-up stage, a pressure build-up stage, a closed-loop control stage, a stable operation stage, a process switching stage, and an end stage.

[0062] Before the process starts, the target pressure is set to 20 mTorr, the initial flow rate of the first flow regulating unit is 1000 sccm, and the initial flow rate of the second flow regulating unit is 200 sccm.

[0063] During the pressure build-up phase, a flow-limiting gasket is installed in the first sub-cooling air duct. Cooling gas sequentially passes through the flow-limiting gasket, the first flow regulation unit, and the gas buffer module into the air guide chamber. When the pressure detection and control module detects that the gas pressure in the cooling air duct downstream of the gas buffer module reaches 95% of the target pressure (i.e., 19 mTorr), the pressure detection and control module drives the first flow regulation unit to shut off and fine-tunes the flow rate of the second flow regulation unit until the gas pressure in the cooling air duct downstream of the gas buffer module stabilizes at 20 mTorr. The pressure detection and control module continues to detect whether the gas pressure in the cooling air duct is 20 mTorr. If the gas pressure in the cooling air duct deviates from 20 mTorr, the flow rate of the first flow regulation unit is fine-tuned.

[0064] During the closed-loop control phase, the adsorption force of the electrostatic chuck increases, and the pressure detection and control module detects that the gas pressure in the cooling air passage is about to reach 18 mTorr. Then, it drives the first flow regulation unit to increase the flow rate, for example, from 200 sccm to 300 sccm.

[0065] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A device for preventing overcharging of cooling gas on the back of an electrostatic chuck, characterized in that, include: A gas regulation module is installed in the cooling gas channel that is connected to the air guide cavity of the electrostatic chuck, and is used to regulate the total flow rate of cooling gas delivered by the cooling gas channel. A gas buffer module includes one or two gas buffer units. Each gas buffer unit includes a flow-limiting channel and a gravity flow-limiting component. The flow-limiting channel is vertically arranged and disposed on the cooling gas passage. The gravity flow-limiting component is movably disposed within the flow-limiting channel. When the cooling gas flows through the flow-limiting channel, the gravity flow-limiting component is displaced under the combined action of its own gravity and the thrust of the cooling gas, thereby limiting the flow of the cooling gas. The pressure detection and control module is electrically connected to the gas regulation module. It is used to detect the gas pressure in the cooling gas passage between the gas buffer module and the gas guide chamber, and drive the gas regulation module to adjust the total flow rate of the cooling gas according to the gas pressure.

2. The anti-overcharge device for the cooling gas on the back of the electrostatic chuck according to claim 1, characterized in that, The gas buffer unit further includes a buffer cavity, which is disposed between the flow-limiting channel and the cooling gas channel, and is used to buffer and reduce the pressure of the cooling gas entering the buffer cavity.

3. The anti-overcharge device for the cooling gas on the back of the electrostatic chuck according to claim 2, characterized in that, The buffer cavity is provided with a buffer chamber, the cross-sectional area of ​​which is larger than that of the flow-limiting channel. The cross-sections of the buffer cavity and the flow-limiting channel are both perpendicular to the flow direction of the cooling gas in the flow-limiting channel.

4. The anti-overcharge device for the cooling gas on the back of the electrostatic chuck according to claim 3, characterized in that, The gravity flow restrictor is spherical.

5. The anti-overcharge device for the cooling gas on the back of the electrostatic chuck according to any one of claims 2-4, characterized in that, A spiral air passage is provided on the inner wall of the flow-limiting channel.

6. The anti-overcharge device for the back cooling gas of the electrostatic chuck according to claim 1, characterized in that, The gas regulation module includes a first flow regulation unit and a second flow regulation unit electrically connected to the pressure detection and regulation module. The first flow regulation unit and the second flow regulation unit are arranged in parallel on the cooling air passage to jointly regulate the flow rate of the cooling gas in the cooling air passage. In the initial stage of gas supply, the flow rate of the first flow regulating unit is the first flow rate, and the flow rate of the second flow regulating unit is the second flow rate. The first flow rate is greater than the second flow rate. The downstream of the gas buffer module is determined along the flow direction of the cooling gas. When the pressure detection and control module detects that the gas pressure in the cooling gas passage downstream of the gas buffer module is greater than or equal to a preset pressure threshold, the pressure detection and control module drives the first flow regulating unit to shut down.

7. The anti-overcharge device for the cooling gas on the back of the electrostatic chuck according to claim 1, characterized in that, It also includes a gas storage module, which is disposed on the cooling air passage. The downstream of the gas storage module is determined along the flow direction of the cooling gas. When the internal pressure of the cooling air passage downstream of the gas storage module is lower than a preset pressure replenishment threshold, the gas storage module replenishes the pressure of the cooling air passage.

8. The anti-overcharge device for the cooling gas on the back of the electrostatic chuck according to claim 7, characterized in that, The gas storage module includes a gas storage tank, an inlet check valve, and an outlet check valve. The gas storage tank is an adjustable-volume gas storage structure with an inlet and an outlet. Both the inlet and outlet are connected to the cooling air passage. The inlet check valve is located at the inlet and allows cooling gas to flow from the cooling air passage to the gas storage tank while preventing cooling gas from flowing from the gas storage tank to the cooling air passage. The outlet check valve is located at the outlet and allows cooling gas to flow from the gas storage tank to the cooling air passage while preventing cooling gas from flowing from the cooling air passage to the gas storage tank. Specifically, when the gas pressure in the cooling air passage is greater than a preset storage pressure threshold, the inlet check valve opens; when the gas pressure in the cooling air passage is lower than a preset pressure replenishment threshold, the outlet check valve opens.

9. The anti-overcharge device for the back cooling gas of the electrostatic chuck according to claim 1, characterized in that, It also includes a recovery module connected to the cooling air duct, used to recover residual gas in the cooling air duct and / or the air guide chamber at the end of the process.

10. An electrostatic chuck, characterized in that, The device includes a suction cup body and an anti-overcharge device for cooling gas on the back of the electrostatic suction cup as described in any one of claims 1-9. The suction cup body has a plurality of air guiding chambers, and the suction surface of the suction cup body has a plurality of cooling air holes, which are connected to the air guiding chambers.

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