Electrostatic chuck air hole cleaning device and method

Abstract

The present invention discloses an electrostatic chuck air hole cleaning device and method, the device comprises: a cleaning rack, a platform is provided on the top of the cleaning rack, and an opening is provided on the platform that penetrates the upper and lower surfaces of the platform; a support ring assembly overlaps and cooperates with the edge of the opening, and is used to support electrostatic chucks of different sizes above the circular hole; a pressurized flushing device comprises a flushing liquid supply end and a flushing pipeline, the flushing liquid supply end is used to press the flushing solution and deionized water into the flushing pipeline at a set pressure, one end of the flushing pipeline is connected to the flushing liquid supply end, and the other end of the flushing pipeline is connected to the air inlet on the back of the electrostatic chuck. The present invention can improve the cleaning effect of the blocked air holes of the electrostatic chuck and improve the stability of the plasma etching process.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor equipment cleaning, and more specifically, relates to an electrostatic chuck air hole cleaning device and method. Background Art

[0002] In the etching chamber of the plasma etcher, the electrostatic chuck (ESC) is a workpiece in direct contact with the wafer. It is crucial in the process to achieve the adsorption and desorption of the wafer. At the same time, adding liquid and gas flow holes in the electrostatic chuck can control the temperature of the electrostatic chuck, so as to achieve temperature control between different areas of the wafer and meet the requirements of the key dimensions of the etching process. A large number of particles will be generated during the process. If the cleaning effect is not good, they will be deposited on the inner wall of the chamber. As the number of hours increases, the deposited layer gradually becomes thicker and falls off, floating in the chamber, causing secondary pollution to the interior. After the particles are deposited, the pores of the electrostatic chuck cannot be partially cleaned by WAC (waferless automatic cleaning) like the particles attached to the surface. Over time, the pores will gradually become blocked, affecting the process parameters and reducing the stability of production. Therefore, it is necessary to deal with the ESC with blocked pores.

[0003] As an important component in the chamber, ESC is highly complex and has a high production cost. If a new electrostatic chuck is replaced after its pores are blocked, the application cost of the chip manufacturer will increase. Therefore, other methods are needed to solve this pore blocking problem. Workpiece cleaning, as a derivative industry of the current semiconductor industry, is of great significance in solving the problem of workpiece contamination. It can not only remove the attached materials on the surface of the workpiece, but also extend the overall service life of the workpiece, reduce costs and increase efficiency. Summary of the invention

[0004] The purpose of the present invention is to provide an electrostatic chuck pore cleaning device and method, so as to improve the cleaning effect of the electrostatic chuck pore blockage and improve the stability of the plasma etching process.

[0005] In a first aspect, the present invention provides an electrostatic chuck air hole cleaning device, wherein the air hole comprises an air inlet located at the back of the electrostatic chuck and a plurality of air outlets located at the front of the electrostatic chuck, wherein the air inlet is connected to each of the air outlets, and the device comprises:

[0006] A cleaning rack, wherein a platform is provided on the top of the cleaning rack, and an opening is provided on the platform that passes through the upper and lower surfaces of the platform;

[0007] A support ring, the support ring overlaps with the edge of the opening and is used to support an electrostatic chuck of corresponding size with its front side facing upward or its back side facing upward above the opening;

[0008] A pressurized flushing device, the pressurized flushing device includes a flushing liquid supply end and a flushing pipeline, the flushing liquid supply end is used to press the flushing solution and deionized water into the flushing pipeline at a set pressure respectively, one end of the flushing pipeline is used to be connected to the flushing liquid supply end, and the other end of the flushing pipeline is used to be connected to the air inlet on the back of the electrostatic chuck.

[0009] Optionally, the support ring comprises a plurality of support rings of different sizes;

[0010] The bottom surface of each support ring is provided with a convex portion or a concave portion, and the top surface is correspondingly provided with a concave portion or a convex portion;

[0011] Of any two support rings with the closest sizes, the support ring with the smaller size is located above the support ring with the larger size, and the raised portion or recessed portion on the bottom surface of the support ring with the smaller size is positioned and matched with the recessed portion or raised portion on the top surface of the support ring with the larger size;

[0012] The platform surface around the opening is provided with a recessed portion or a raised portion which is positioned and matched with the raised portion or the recessed portion of the bottom surface of the largest supporting ring;

[0013] The size of the uppermost support ring corresponds to the size of the electrostatic chuck, and the inner diameter of the uppermost support ring is smaller than the diameter of the back side of the electrostatic chuck and larger than the diameter of the front side of the electrostatic chuck.

[0014] Optionally, the flushing liquid supply end includes a flushing liquid storage tank and a pressure pump, and the pressure pump is used to pump the liquid in the flushing liquid storage tank into the flushing pipeline at a set pressure.

[0015] Optionally, a flushing nozzle is provided at the other end of the flushing pipeline, and the flushing nozzle includes a nozzle, a bracket and a sealing ring. The bracket and the sealing ring are sleeved on the water outlet end of the nozzle, and the bracket is arranged on the side of the sealing ring away from the water outlet end. The water outlet end of the nozzle is conical.

[0016] Optionally, it further comprises: a detection tool for measuring the water output of each of the air outlets when the electrostatic chuck is placed face down on the support ring and liquid is flushed into the air inlet; and / or

[0017] It is used to measure the water outlet height of each of the air outlet holes when the electrostatic chuck is placed on the support ring with its front side facing upward and liquid is flushed into the air inlet hole.

[0018] In a second aspect, the present invention provides a method for cleaning air holes of an electrostatic chuck, wherein the air holes include an air inlet located on the back of the electrostatic chuck and a plurality of air outlets located on the front of the electrostatic chuck, wherein the air inlet is connected to each of the air outlets, and the method includes:

[0019] Determine the blocking rate of each air outlet on the front of the electrostatic chuck;

[0020] Sampling the obstruction in the air outlet and analyzing the composition of the obstruction;

[0021] A corresponding flushing solution is prepared according to the composition of the blockage, and the flushing pressure is determined according to the blockage rate;

[0022] Flushing the flushing solution into the air inlet holes of the electrostatic chuck according to the flushing pressure to clean the air holes until the opening rate of any air outlet hole is greater than a first set threshold value;

[0023] Flushing deionized water into the air inlet, and judging whether the cleaning effect of the air hole meets the set conditions according to the water output of the air outlet;

[0024] When the cleaning effect of the air hole does not meet the set condition, the step of flushing the flushing solution into the air inlet hole of the electrostatic chuck according to the flushing pressure to clean the air hole is re-executed until the cleaning effect of the air hole meets the set condition.

[0025] Optionally, the method further comprises: when the cleaning effect of the air hole satisfies the set condition, introducing a purge gas into the air inlet of the electrostatic chuck for a first set time, and placing the electrostatic chuck in a vacuum drying oven for drying;

[0026] After drying is completed, the purge gas is introduced into the air inlet of the electrostatic chuck for a second set time, and the purge material is collected at the air outlet, and the particle number and composition of the purge material are analyzed until the particle number of the purge material is less than the second set threshold value and the composition of the purge material does not contain polluting elements.

[0027] Optionally, the step of injecting deionized water into the air inlet and judging whether the cleaning effect of the through hole meets a set condition according to the water output from the air outlet comprises:

[0028] Place the electrostatic chuck face down, flush deionized water into the air inlet, measure the water output of each air outlet per unit time, calculate the water output volume difference between any two air outlets, and determine whether the water output volume difference is less than the third set threshold.

[0029] Optionally, the step of flushing deionized water into the air inlet and judging whether the cleaning effect of the through hole meets a set condition according to the water output from the air outlet further includes:

[0030] If the volume difference of the water output is less than the third set threshold, flip the electrostatic chuck so that the front side is facing upward, flush deionized water into the air inlet, increase the flushing pressure, measure the height of the water column of each air outlet, and calculate the height difference between the highest water column and the lowest water column to determine whether the height difference is less than the fourth set threshold.

[0031] Optionally, before flushing the flushing solution into the air inlet of the electrostatic chuck according to the flushing pressure to clean the air inlet, the method further comprises:

[0032] Immersing the front surface of the electrostatic chuck in deionized water at a set temperature for a fifth set time;

[0033] The electrostatic chuck is taken out and cooled to room temperature, and the front side of the electrostatic chuck is immersed in an immersion liquid for a sixth set time, wherein the immersion liquid contains an alkaline solute and a surfactant;

[0034] The electrostatic chuck is taken out, and the front side of the electrostatic chuck is immersed in deionized water at room temperature for a seventh set time to remove the immersion liquid remaining on the surface.

[0035] Optionally, configuring a corresponding flushing solution according to the composition of the blockage includes:

[0036] When the main component of the blockage is a polymer, the components of the flushing solution include: an organic solvent, deionized water, an alkaline solute and a surfactant;

[0037] When the main component of the blockage is metal oxide, the components of the flushing solution include: deionized water, acidic solute and surfactant.

[0038] The beneficial effects of the present invention are:

[0039] The device of the present invention can support electrostatic chucks of different sizes through the cleaning frame and the supporting ring assembly, and can pressurize the flushing solution to flush the air holes of the electrostatic chuck through the pressurized flushing device.

[0040] The method of the present invention realizes a method for cleaning the blocked pores on an electrostatic chuck and determining the cleaning effect. First, the components of the blockages in the blocked pores are analyzed, and a corresponding flushing solution is configured according to the components of the blockages. The pores are pressurized and flushed through a circulation method. Then, the apertures of the cleaned pores are observed and tested for flow, so as to determine whether the blocked pores are cleaned. By determining whether the pores are cleaned in a simple manner, the cumbersome process of on-machine verification after cleaning can be avoided, the cleaning process can be simplified, the cleaning efficiency can be improved, and at the same time, the reusability of the electrostatic chuck can be improved, thereby achieving the effect of reducing costs and increasing efficiency.

[0041] The system of the present invention has other characteristics and advantages, which will be apparent from the drawings incorporated herein and the following detailed description, or will be described in detail in the drawings incorporated herein and the following detailed description, which together serve to explain the specific principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, in which like reference numerals generally represent like components.

[0043] Figure 1a , Figure 1b Schematic diagram showing the front and back of an electrostatic chuck

[0044] Figure 1c A cross-sectional view of an electrostatic chuck is shown.

[0045] Figure 2a A schematic structural diagram of a cleaning frame in an electrostatic chuck air hole cleaning device according to embodiment 1 of the present invention is shown.

[0046] Figure 2b A top view of a cleaning rack platform in an electrostatic chuck air hole cleaning device according to embodiment 1 of the present invention is shown.

[0047] Figure 2c Shown along Figure 2b Sectional view of AA.

[0048] Figure 3 A structural diagram of multiple support rings of different sizes in an electrostatic chuck air hole cleaning device according to Example 1 of the present invention is shown.

[0049] Figure 4 A schematic diagram showing a plurality of support rings of different sizes supporting an electrostatic chuck in an electrostatic chuck air hole cleaning device according to Example 1 of the present invention.

[0050] Figure 5 A schematic diagram showing the connection between a pressurized flushing device and an electrostatic chuck in an electrostatic chuck air hole cleaning device according to Example 1 of the present invention is shown.

[0051] Figure 6 A schematic structural diagram of a flushing nozzle in an electrostatic chuck air hole cleaning device according to Example 1 of the present invention is shown.

[0052] Figure 7 A schematic structural diagram of a water column height measuring tool in an electrostatic chuck air hole cleaning device according to Example 1 of the present invention is shown.

[0053] Figure 8A flow chart showing the steps of an electrostatic chuck air hole cleaning method according to embodiment 2 of the present invention is shown.

[0054] Fig. 9 A schematic diagram showing pressurized flushing of a static chuck using an electrostatic chuck air hole cleaning device in Example 2 of the present invention is shown.

[0055] Fig.10 A schematic diagram showing the use of an electrostatic chuck air hole cleaning device to flip a static chuck and allow water to enter the chuck in Embodiment 2 of the present invention is shown. DETAILED DESCRIPTION

[0056] The prior art discloses a pore cleaning method, which is mainly aimed at cleaning the ESC pore blockage problem in CVD and PVD machines. A needle-shaped spiral hard probe is designed to mechanically loosen the hole blockage, and then the hole is cleaned with an acidic solution composed of nitric acid and hydrofluoric acid. Finally, the residual reagent is removed in a plasma atmosphere to stabilize the state of the ESC after cleaning. This solution designs a pore unblocking probe, which mechanically rotates the probe from the ESC surface into the hole to unblock the blockage in the pore.

[0057] This solution has the following problems:

[0058] 1. This technology mainly uses a hard needle-like object to penetrate into the pores and clean the blockages in the holes in a rotating manner. Since a hard mechanical method is used to penetrate into the pores, and the ceramic surface of the ESC is relatively soft, it is easy to scratch the surface of the ESC pores, causing the problem of wafer adsorption and leakage. At the same time, it may also cause damage to the side walls of the pores, and the damage is not easy to observe, resulting in the actual pore flow rate not matching the set pore flow rate, resulting in deviations during the process operation;

[0059] 2. This technology is mainly used for deposition coating machines such as CVD and PVD. The deposits of coating machines are mainly metals. A single acid-based cleaning solution cannot completely and effectively clean the deposits mainly composed of polymers in the ESC pores of etching machines.

[0060] 3. The loosening process during mechanical grinding will cause the blockage to penetrate further into the pores. Although the cleaning will be done again with liquid medicine later, it increases the difficulty and cost of cleaning, and it may not be completely cleaned;

[0061] 4. Use plasma atmosphere to stabilize the ESC. Even non-reactive gases, such as argon, will still penetrate into the pores and physically bombard the pore walls, causing damage.

[0062] 5. After the ESC pores are cleaned, this technology uses electrical testing to evaluate the cleaning effect. The evaluation method is complex and difficult to implement, and there is no clear judgment effect on the cleaning effect, making it difficult to intuitively reflect the cleaning effect.

[0063] The present invention proposes an electrostatic chuck pore cleaning device and a cleaning method, which can significantly clean and remove deposited particles in the pores of the electrostatic chuck of an etcher, and determine the cleaning effect by means of detection means, thereby achieving the effect of reusing the hole-blocking electrostatic chuck, improving the stability of the plasma etching process, and reducing production costs.

[0064] The present invention will be described in more detail below with reference to the accompanying drawings. Although preferred embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0065] Example 1

[0066] like Figure 1a-Figure 1c As shown, the front of the electrostatic chuck 1 has two inner and outer circles of air outlet holes 3, and the back center of the electrostatic chuck 1 has an air inlet hole 2, and the air inlet hole 2 is connected to multiple air outlet holes 3 through a flow channel provided in the electrostatic chuck 1. Those skilled in the art should understand that the electrostatic chuck to which the present invention is applicable has no restrictions on the number and arrangement of air inlets and air outlet holes, and may have more or fewer air outlet holes, or more air inlets. For example, the air holes of the electrostatic chuck can blow gas such as helium to the wafer when the wafer is processed to control the temperature of the wafer.

[0067] This embodiment provides an electrostatic chuck air hole cleaning device, including: a cleaning frame 4, a support ring and a pressurized flushing device 14.

[0068] like Figure 2a As shown, a platform 5 is provided on the top of the cleaning rack 4, and an opening 6 is provided on the platform 5 that passes through the upper and lower surfaces of the platform 5. The opening 6 in this embodiment is circular; the support ring assembly overlaps and cooperates with the edge of the opening 6 to support electrostatic chucks 1 of different sizes above the opening 66;

[0069] The support ring overlaps with the edge of the opening 6 to support the electrostatic chuck of corresponding size with the front side facing upward or the back side facing upward above the opening 6; preferably, the support ring includes a plurality of support rings 9 of different sizes, each of which has a raised portion or a recessed portion on the bottom surface and a recessed portion or a raised portion on the top surface; wherein the support method of the front side facing upward is as follows Fig.10As shown, the inner diameter of the support ring 9 at the top needs to be smaller than the diameter of the back of the electrostatic chuck 1; the support method with the back facing upward is as follows Figure 4 As shown, the inner diameter of the uppermost support ring 9 needs to be larger than the diameter of the front surface of the electrostatic chuck 1 .

[0070] Of any two support rings with the closest sizes, the support ring with the smaller size is located above the support ring with the larger size, and the raised portion or recessed portion on the bottom surface of the support ring with the smaller size is positioned and matched with the recessed portion or raised portion on the top surface of the support ring with the larger size;

[0071] The surface of the platform 5 around the opening 6 is provided with a recessed portion or a raised portion which is positioned and matched with the raised portion or the recessed portion of the bottom surface of the largest supporting ring;

[0072] The size of the uppermost support ring corresponds to the size of the electrostatic chuck 1 , and the inner diameter of the uppermost support ring is smaller than the diameter of the back side of the electrostatic chuck 1 and larger than the diameter of the front side of the electrostatic chuck 1 .

[0073] exist Figure 3 and Figure 4 In the example of, the support ring in this embodiment includes a plurality of support rings 9 of different sizes, each support ring 9 can be used to support an electrostatic chuck 1 of a corresponding size; a protrusion 8 is provided on the bottom surface of the support ring 9, a recessed portion 7 is provided on the top surface of the support ring 9, and the inner edge of the support ring 9 overlaps with the edge of the electrostatic chuck 1; of any two support rings 9 with the closest sizes, the protrusion 8 on the bottom surface of the support ring 9 with the smaller size cooperates with the recessed portion 7 on the top surface of the support ring 9 with the larger size;

[0074] like Figure 2a-2c As shown, a recessed portion 18 is provided on the surface of the platform 5 around the opening 6 on the top platform 5 of the cleaning rack 4 to match the raised portion 8 on the bottom surface of the largest supporting ring 9 .

[0075] In other embodiments, it is also possible to choose to set a groove on the bottom surface of each support ring 9 and a protrusion on the top surface of the support ring, and correspondingly, a protrusion that cooperates with the groove on the bottom surface of the largest support ring 9 is set on the surface of the platform 5 around the opening 6 on the platform 5.

[0076] like Figure 5 As shown, the pressurized flushing device 14 in this embodiment includes a flushing liquid supply end and a flushing pipeline 17. The flushing liquid supply end is used to press the flushing solution and deionized water into the flushing pipeline 17 at a set pressure, respectively. One end of the flushing pipeline 17 is connected to the flushing liquid supply end, and the other end of the flushing pipeline 17 is connected to the air inlet 2 on the back of the electrostatic chuck 1.

[0077] The flushing liquid supply end includes a flushing liquid storage tank 15 and a pressure pump 16, and the pressure pump 16 is used to pump the flushing liquid in the flushing liquid storage tank 15 into the flushing pipeline 17 at a set pressure. Figure 6 As shown, the other end of the flushing pipeline is provided with a flushing nozzle, which is connected to the air inlet 2 on the back of the electrostatic chuck 1 through the flushing nozzle. The flushing nozzle includes a nozzle 10, a tray 11 and a sealing ring 12. The tray 11 and the sealing ring 12 are sleeved on the water outlet end of the nozzle 10, and the tray 11 is arranged on the side of the sealing ring 12 away from the water outlet end. The water outlet end of the nozzle 10 is conical; preferably, the sealing ring 12 is made of flexible material, and the material of the tray 11 is polytetrafluoroethylene.

[0078] The electrostatic chuck air hole cleaning device of this embodiment further includes a detection tool for measuring the water output of each of the air outlets when the electrostatic chuck 1 is placed face down on the support ring 9 and liquid is flushed into the air inlet 2; and / or

[0079] It is used to measure the water outlet height of each of the air outlet holes 3 when the electrostatic chuck 1 is placed on the support ring 9 with its front side facing upward and liquid is flushed into the air inlet hole.

[0080] Specifically, the measuring tool is used to measure the cleaning effect of the through hole according to the water outlet of the air outlet 2 on the front side of the electrostatic chuck 1 after the through hole is cleaned.

[0081] The detection tool of this embodiment may include at least one of a measuring cylinder and a tape measure. The measuring cylinder is used to measure the water flow rate of each air outlet 3 when the electrostatic chuck 1 is placed face down on the support ring 9 and liquid is flushed into the air inlet 2. The tape measure is used to measure the height of the water column sprayed from the multiple air outlets 3 on the front of the electrostatic chuck 1 when the electrostatic chuck 1 is placed face up on the support ring 9 and liquid is flushed into the air inlet 2. Figure 7 As shown, the tape measure of this embodiment includes a tape measure portion 13a and a conical weight 13b fixed to the bottom of the tape measure portion 13a. The cleaning effect of the air holes can be evaluated by measuring the water flow rate of each air outlet 3 with a measuring cylinder and / or measuring the height of the water column sprayed from multiple air outlets 3 with a tape measure.

[0082] Example 2

[0083] like Figure 8 As shown, this embodiment provides an electrostatic chuck pore cleaning method, the method comprising:

[0084] S1: Determine the blocking rate of each air outlet on the front side of the electrostatic chuck;

[0085] S2: sampling the obstruction in the air outlet and analyzing the components of the obstruction;

[0086] S3: preparing a corresponding flushing solution according to the composition of the blockage, and determining the flushing pressure according to the pore blocking rate;

[0087] S4: flushing the flushing solution into the air inlet holes of the electrostatic chuck according to the flushing pressure to clean the air holes until the opening rate of any air outlet hole is greater than a first set threshold;

[0088] S5: flushing deionized water into the air inlet, and judging whether the cleaning effect of the air hole meets the set conditions according to the water output of the air outlet; when the cleaning effect of the air hole does not meet the set conditions, re-execute the step of flushing the flushing solution into the air inlet of the electrostatic chuck according to the flushing pressure to clean the air hole until the cleaning effect of the air hole meets the set conditions.

[0089] The method of this embodiment can be completed using the electrostatic chuck pore cleaning device described in Example 1, and the specific steps are as follows:

[0090] S1: determining the blocking rate of each air outlet 3 on the front side of the electrostatic chuck 1;

[0091] Specifically, the pores of the electrostatic chuck 1 are magnified and observed to determine the degree of pore blockage. The pores are magnified and observed using an optical microscope, the actual diameter of the pores is measured, the ratio of the difference between the initial diameter and the actual diameter to the initial diameter is calculated, and the blockage rate of any pore is determined, so as to judge the degree of blockage of the pores on the surface of the electrostatic chuck 1.

[0092] S2: sampling the obstruction in the air outlet 3 and analyzing the composition of the obstruction;

[0093] Specifically, the plugging material in the pores is sampled using a needle, and its composition is analyzed using an energy dispersive X-ray spectrometer (EDX).

[0094] S3: preparing a corresponding flushing solution according to the composition of the blockage, and determining the flushing pressure according to the pore blocking rate;

[0095] Specifically, a corresponding flushing solution is prepared according to the composition of the pore blockage material, and the flushing water pressure is determined according to the pore blockage rate, preferably taking the pores with the highest degree of blockage as the basis.

[0096] Prepare a pore flushing solution. The pore blockage is related to the wafer film layer and the specific process. The flushing solution composition needs to be determined according to the blockage composition. If the polymer is the main component of the blockage, that is, C, O, Si, S, F, Cl, etc. are the main elements, then the flushing solution uses an organic solvent and deionized water as a mixed solvent, mainly weakly alkaline, and adds a small amount of surfactants. Weakly alkaline solutions have good solubility for polymers and can effectively clean the blockage. Preferably, the components of the flushing solution include: 15-25 parts of at least one of ethanol, isopropanol or acetone and 15-40 parts of deionized water as a mixed solvent, 1-5 parts of at least one of sodium hydroxide, potassium hydroxide or sodium carbonate as an alkaline solute, and 0.5-5 parts of at least one of sodium dodecyl sulfate or sodium dodecylbenzene sulfonate as a surfactant.

[0097] If metal oxides are the main components, i.e. Al, O, Si, Cu, Ti, W, Cr, etc. are the main elements, then the flushing solution mainly uses deionized water as the solute, which is mainly weakly acidic and neutral, and a small amount of oxidant and surfactant are added. Weakly acidic solutions have good solubility for metal oxides and can effectively clear blockages. Preferably, the flushing solution includes: 20-50 parts of deionized water as a solvent, 1-8 parts of at least one of phosphoric acid, hydrochloric acid, nitric acid, hydrofluoric acid, citric acid, hydrofluoric acid, and acrylic acid as an acidic solute, 0.5-6 parts of hydrogen peroxide, and 0.5-5 parts of at least one of sodium dodecyl sulfate or sodium dodecylbenzene sulfonate as a surfactant.

[0098] In this embodiment, before executing step S4, the process further includes:

[0099] S001: Immersing the front surface of the electrostatic chuck 1 in deionized water at a set temperature for a fifth set time;

[0100] Specifically, since the clogging of the pores on the ceramic surface (front) of the electrostatic chuck 1 is relatively serious, the surface of the electrostatic chuck 1 needs to be pretreated before flushing: the ceramic surface of the electrostatic chuck 1 is immersed in deionized water, the water temperature is preferably controlled to be 40-80°C, and the immersion time (the fifth set time) is preferably 60min-90min. This operation mainly uses deionized water at an appropriate temperature to soften the clogged pores on the surface. Higher temperatures can accelerate molecular movement and the softening effect is obvious, but too high a temperature can easily damage the ceramic coating on the surface of the electrostatic chuck 1.

[0101] S002: taking out the electrostatic chuck 1 and cooling it to room temperature, and immersing the front side of the electrostatic chuck 1 in an immersion liquid for a sixth set time, wherein the immersion liquid contains an alkaline solute and a surfactant;

[0102] Specifically, the electrostatic chuck 1 is taken out and cooled to room temperature, and the ceramic surface continues to be immersed in the immersion liquid. The immersion time (the sixth set time) is preferably 30-45 minutes. The alkaline solute and surfactant added to the immersion liquid have a more obvious immersion effect than deionized water, which weakens the binding force between the blockage and the hole wall, and has a further softening effect, which is convenient for the subsequent cleaning of the hole. Preferably, the composition of the immersion liquid includes: 2-5 parts of inorganic alkali (including at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, ammonia water, and sodium carbonate), 0.5-5 parts of surfactant (including at least one of alkylbenzene sulfonate, alkyl sulfate, sulfate ester salt, succinate ester sulfonate, and fatty acid methyl ester sulfonate), and 70-90 parts of deionized water. In this method, the purpose of first soaking the front side of the electrostatic chuck 1 in deionized water of a set temperature and then soaking it in the soaking liquid is: first, using deionized water of a certain temperature can accelerate the molecular movement of the blockage, soften the blockage and increase the fluffiness of the blockage, thereby improving the softening effect of the blockage using the chemical soaking liquid, and then improving the subsequent cleaning effect of the blockage. If the high-temperature deionized water soaking is omitted and the chemical soaking liquid is directly used to soften the blockage, the softening effect of the blockage may be poor, thereby affecting the subsequent cleaning effect.

[0103] S003: taking out the electrostatic chuck 1, and immersing the front side of the electrostatic chuck 1 in deionized water at room temperature for a seventh set time to remove the immersion liquid remaining on the surface.

[0104] Specifically, the electrostatic chuck 1 is taken out and continues to be immersed in deionized water at room temperature. The immersion time (the seventh set time) is preferably 20-40 minutes to remove most of the residual immersion liquid on the surface to avoid interference between the residual immersion liquid on the surface and the subsequent cleaning liquid.

[0105] S4: flushing the flushing solution into the air inlet holes of the electrostatic chuck according to the flushing pressure to clean the air holes until the opening rate of any air outlet hole is greater than a first set threshold;

[0106] This step specifically includes:

[0107] S401: according to the size of the electrostatic chuck 1, the electrostatic chuck 1 is placed face down on the platform 5 of the cleaning rack 4 using the support ring assembly, the flushing nozzle is connected to the air inlet 2 on the back of the electrostatic chuck 1, and the flushing solution is flushed into the air inlet 2 of the electrostatic chuck 1 according to the flushing pressure by the pressurized flushing device 14, and the flushing is continued for a third set time.

[0108] Specifically, Fig. 9As shown, the electrostatic chuck 1 is placed with the ceramic surface facing downward on the cleaning rack 4. Preferably, a shock-absorbing cotton can be placed at the contact position between the electrostatic chuck 1 and the cleaning rack 4 to prevent scratches on the surface of the electrostatic chuck 1. The flushing solution is connected to the back of the static chuck and the air inlet 2 through a pressurizing device, and the corresponding flushing pressure is set for flushing. The flushing time (the third set time) is preferably 30-60 minutes.

[0109] S402: Determine whether the opening rate of any air outlet 3 is greater than a first set threshold value, if so, execute step S5, otherwise return to step S401;

[0110] Specifically, the pores of the electrostatic chuck 1 can be enlarged and observed every 30-60 minutes to determine the ratio of the through hole diameter to the initial diameter, and judge whether the pore opening rate is greater than a first set threshold value. The first set threshold value is preferably 65%, that is, judge whether the pore opening rate is above 65%. If the requirement is not met, return to step S401 to continue flushing until any pore meets the requirement, and then execute step S5.

[0111] S5: flushing deionized water into the air inlet, and judging whether the cleaning effect of the through hole meets the set conditions according to the water outlet of the air outlet; when the cleaning effect of the air hole does not meet the set conditions, re-execute the step of flushing the flushing solution into the air inlet of the electrostatic chuck according to the flushing pressure to clean the air hole until the cleaning effect of the air hole meets the set conditions.

[0112] This step specifically includes:

[0113] S501: Place the electrostatic chuck face downward, flush deionized water into the air inlet, measure the water output per unit time of each air outlet, calculate the water output volume difference between any two air outlets, and determine whether the water output volume difference is less than a third set threshold.

[0114] Specifically, the electrostatic chuck 1 is placed face down on the cleaning rack 4, and deionized water is flushed into the air inlet at the back of the electrostatic chuck 1. A single air inlet corresponds to all the air outlets 3, and all the air outlets 3 can be flushed at the same time. The liquid flowing out of any air outlet is collected using a measuring cylinder, and the volume difference of the water output of any two air outlets 3 is calculated; then, it is determined whether the volume difference of the water output is less than a third set threshold value. Preferably, the third set threshold value is 10%, that is, the volume difference of the water flow of any two air outlets per unit time needs to be less than 10%; if the volume difference of the water flow of any two air outlets is less than 10%, it can be considered that a better cleaning effect has been achieved, and step S502 can be executed. Optionally, step S6 can also be executed directly. If the above conditions are not met, return to step S4 for re-flushing.

[0115] In this embodiment, in order to further verify the flushing effect, optionally, this step also includes:

[0116] S502: If the volume difference of the water output is less than the third set threshold, flip the electrostatic chuck to face up, flush deionized water into the air inlet, increase the flushing pressure, measure the height of the water column of each air outlet, and calculate the height difference between the highest water column and the lowest water column to determine whether the height difference is less than the fourth set threshold.

[0117] Specifically, when it is determined that the water volume difference between any two water outlets is less than the third set threshold, in order to further evaluate the cleaning effect, the electrostatic chuck 1 can be reversed and placed on the cleaning rack 4, with the front side facing up and the back side placed on the cleaning rack 4, and deionized water is introduced from the back air inlet. Fig.10 As shown, increase the water pressure, use a tapered ruler 13a with a conical weight 13b tied to the bottom to measure the height of the water column pressed out of the air hole, and calculate the height difference between the highest water column and the lowest water column; the fourth set threshold is preferably 5%, that is, the height difference between the highest and lowest water columns should be less than 5%. If the above two conditions are met at the same time, it can be determined that any air hole is not obviously blocked, and normal air flow can be guaranteed after the machine is put on, and then step S6 can be executed; if either of the two conditions is not met, it is necessary to return to step S4 until both of the above conditions are met.

[0118] In other embodiments, this step may also evaluate the cleaning effect by only measuring the height difference of the water columns of the plurality of air outlet holes 3 .

[0119] In order to further improve the cleaning effect of the pores, preferably the method of this embodiment further includes:

[0120] Step S6: When the cleaning effect of the air holes in step S5 meets the set conditions, a purge gas is introduced into the air inlet 2 of the electrostatic chuck 1 for a first set time, and the electrostatic chuck 1 is placed in a vacuum drying oven for drying;

[0121] Specifically, the purge gas is preferably high-purity nitrogen (above 99.99999%). After the pores are purged with high-purity nitrogen (above 99.99999%) for a first set time, which is preferably 30-60 minutes, the electrostatic chuck 1 is placed in a vacuum drying oven for drying, and the heating and cooling speed is controlled to be less than 1°C / min to prevent the temperature from changing too quickly, resulting in excessive local temperature differences in the electrostatic chuck 1 and cracking on the surface of the electrostatic chuck 1.

[0122] S7: After drying is completed, the purge gas is introduced into the air inlet of the electrostatic chuck 1 for a second set time, and the purge material is collected at the air outlet 3. The particle number and composition of the purge material are analyzed. If the particle number of the purge material is less than the second set threshold value and the composition of the purge material does not contain polluting elements, the cleaning is completed.

[0123] Specifically, continue to use high-purity nitrogen (99.99999% or more) to purge the pores for the second set time, which is preferably 10 minutes, and collect the purged material at the outlet, and analyze the number and composition of the purged material particles. If the number of particles above 0.3um is less than the second set threshold, which is preferably three, and there are no obvious polluting elements, such as carbon, silicon, oxygen, aluminum, titanium, yttrium, chromium, copper, etc., it can be proved that the pore cleaning has achieved the use effect and can operate normally after being installed. Otherwise, return to step S4 and clean again.

[0124] Compared with the prior art, the present invention has the following advantages:

[0125] 1. Compared with the prior art method of using a hard needle-like object to penetrate into the pore and clean the blockage in the hole in a rotating manner, the present method completely uses a flushing liquid to clean the pore, which will not cause damage to the surface of the electrostatic chuck, nor will it cause scratches on the side walls of the pore. Therefore, the problem of the actual flow rate of the pore not being consistent with the set flow rate after cleaning will not occur. At the same time, there is no problem of loosening during the mechanical grinding process of the needle-like object in the prior art, which will cause the blockage to further penetrate into the interior of the pore and increase the difficulty of subsequent cleaning. Moreover, the present invention does not have the problem of damaging the inner wall of the pore using a plasma atmosphere in the prior art.

[0126] 2. This method configures the corresponding flushing solution according to the composition of the blockage. Compared with the existing technology that uses a single acid-based cleaning solution, it can more specifically remove blockages of different forms and achieve better cleaning effects.

[0127] 3. Through simple flushing liquid cleaning and a simple judgment method using the difference in water flow rate and water column height at the air outlet, the blocked air holes of the electrostatic chuck can be cleaned and it can be determined whether the conditions for use are met, which reduces the tediousness of cleaning and machine verification, improves cleaning efficiency, and can also restore the blocked air holes of the electrostatic chuck to a usable state to meet the needs of the machine.

[0128] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. An electrostatic chuck air hole cleaning device, wherein the air hole comprises an air inlet located at the back of the electrostatic chuck and a plurality of air outlets located at the front of the electrostatic chuck, wherein the air inlet is connected to each of the air outlets. It is characterized in that The device comprises: A cleaning rack, wherein a platform is provided on the top of the cleaning rack, and an opening is provided on the platform that passes through the upper and lower surfaces of the platform; A support ring, the support ring overlaps with the edge of the opening and is used to support an electrostatic chuck of corresponding size with its front side facing upward or its back side facing upward above the opening; A pressurized flushing device, the pressurized flushing device comprising a flushing liquid supply end and a flushing pipeline, the flushing liquid supply end is used to press the flushing solution and deionized water into the flushing pipeline at a set pressure, one end of the flushing pipeline is used to be connected to the flushing liquid supply end, and the other end of the flushing pipeline is used to be connected to the air inlet on the back of the electrostatic chuck; A detection tool, used to measure the water output of each of the air outlets when the electrostatic chuck is placed face down on the support ring and liquid is flushed into the air inlet; and / or Used to measure the water outlet height of each of the air outlets when the electrostatic chuck is placed on the support ring with the front side facing upward and liquid is flushed into the air inlet; The cleaning device can judge whether the cleaning effect of the air outlet meets the set conditions based on the volume difference of water output per unit time of any two air outlets measured by the detection tool; and / or the height difference between the highest water column and the lowest water column of the air outlet measured by the detection tool.

2. The device according to claim 1, It is characterized in that The support ring includes a plurality of support rings of different sizes; The bottom surface of each support ring is provided with a convex portion or a concave portion, and the top surface is correspondingly provided with a concave portion or a convex portion; Of any two support rings with the closest sizes, the support ring with the smaller size is located above the support ring with the larger size, and the raised portion or recessed portion on the bottom surface of the support ring with the smaller size is positioned and matched with the recessed portion or raised portion on the top surface of the support ring with the larger size; The platform surface around the opening is provided with a recessed portion or a raised portion which is positioned and matched with the raised portion or the recessed portion of the bottom surface of the largest supporting ring; The size of the uppermost support ring corresponds to the size of the electrostatic chuck, and the inner diameter of the uppermost support ring is smaller than the diameter of the back side of the electrostatic chuck and larger than the diameter of the front side of the electrostatic chuck.

3. The device according to claim 1, It is characterized in that The flushing liquid supply end includes a flushing liquid storage tank and a pressure pump, and the pressure pump is used to pump the liquid in the flushing liquid storage tank into the flushing pipeline at a set pressure.

4. The device according to claim 1, It is characterized in that A flushing nozzle is arranged at the other end of the flushing pipeline, and the flushing nozzle includes a nozzle, a bracket and a sealing ring. The bracket and the sealing ring are sleeved on the water outlet end of the nozzle, and the bracket is arranged on the side of the sealing ring away from the water outlet end. The water outlet end of the nozzle is conical.

5. A method for cleaning air holes of an electrostatic chuck, wherein the air holes include an air inlet located at the back of the electrostatic chuck and a plurality of air outlets located at the front of the electrostatic chuck, wherein the air inlet is connected to each of the air outlets. It is characterized in that The method comprises: Determine the blocking rate of each air outlet on the front of the electrostatic chuck; Sampling the obstruction in the air outlet and analyzing the composition of the obstruction; A corresponding flushing solution is prepared according to the composition of the blockage, and the flushing pressure is determined according to the blockage rate; Flushing the flushing solution into the air inlet holes of the electrostatic chuck according to the flushing pressure to clean the air holes until the opening rate of any air outlet hole is greater than a first set threshold value; Flushing deionized water into the air inlet, and judging whether the cleaning effect of the air hole meets the set conditions according to the water output of the air outlet; When the cleaning effect of the air hole does not meet the set condition, re-performing the step of flushing the flushing solution into the air inlet hole of the electrostatic chuck according to the flushing pressure to clean the air hole until the cleaning effect of the air hole meets the set condition; Wherein, the step of flushing deionized water into the air inlet and judging whether the cleaning effect of the air outlet meets the set conditions according to the water discharge condition of the air outlet comprises: Place the electrostatic chuck face down, flush deionized water into the air inlet, measure the water output of each air outlet per unit time, calculate the water output volume difference between any two air outlets, and determine whether the water output volume difference is less than the third set threshold.

6. The cleaning method according to claim 5, It is characterized in that Also includes: When the cleaning effect of the air holes meets the set conditions, a purge gas is introduced into the air inlet of the electrostatic chuck for a first set time, and the electrostatic chuck is placed in a vacuum drying oven for drying; After drying is completed, the purge gas is introduced into the air inlet of the electrostatic chuck for a second set time, and the purge material is collected at the air outlet, and the particle number and composition of the purge material are analyzed until the particle number of the purge material is less than the second set threshold value and the composition of the purge material does not contain polluting elements.

7. The method according to claim 5, It is characterized in that The step of injecting deionized water into the air inlet and judging whether the cleaning effect of the air outlet meets the set conditions according to the water output of the air outlet may further include: If the volume difference of the water output is less than the third set threshold, flip the electrostatic chuck so that the front side is facing upward, flush deionized water into the air inlet, increase the flushing pressure, measure the height of the water column of each air outlet, and calculate the height difference between the highest water column and the lowest water column to determine whether the height difference is less than the fourth set threshold.

8. The method according to claim 5, It is characterized in that Before flushing the flushing solution into the air inlet of the electrostatic chuck according to the flushing pressure to clean the air inlet, the method further comprises: Immersing the front surface of the electrostatic chuck in deionized water at a set temperature for a fifth set time; Taking out the electrostatic chuck and cooling it to room temperature, immersing the front side of the electrostatic chuck in an immersion liquid for a sixth set time, wherein the immersion liquid contains an alkaline solute and a surfactant; The electrostatic chuck is taken out, and the front side of the electrostatic chuck is immersed in deionized water at room temperature for a seventh set time to remove the immersion liquid remaining on the surface.

9. The method according to claim 5, It is characterized in that The flushing solution configured according to the components of the blockage includes: When the main component of the blockage is a polymer, the components of the flushing solution include: an organic solvent, deionized water, an alkaline solute and a surfactant; When the main component of the blockage is metal oxide, the components of the flushing solution include: deionized water, acidic solute and surfactant.

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