A freezing cleaning method and device for removing micro-particles

Abstract

The present application provides a freezing cleaning method and device for removing tiny particles, the method comprising: cooling the substrate to be cleaned to a certain temperature; spraying ultrapure deionized water on the substrate to be cleaned to form a water film; freezing first to form ice particles where particles exist, and the ice particles float up and leave the retention layer; spraying ultrapure deionized water to melt the ice particles and spin-drying the substrate to be cleaned. The device comprises: a rotatable platform for carrying the substrate to be cleaned; a cooling member arranged in the rotatable platform and located below the substrate to be cleaned, the cooling member being used to cool the substrate to be cleaned; a movable arm located above the rotatable platform, a nozzle being arranged on the movable arm, the spraying direction of the nozzle being toward the substrate to be cleaned, and the movable arm driving the nozzle to spray ultrapure deionized water on the substrate to be cleaned. The treatment scheme of the present application improves the efficiency of removing tiny particles.

Description

Technical Field

[0001] The present application relates to the technical field of cleaning, and particularly to a freezing cleaning method and device for removing micro-particles. Background Art

[0002] As the semiconductor manufacturing process progresses from deep ultraviolet light (DUV) to extreme ultraviolet light (EUV), the sizes of patterns on photomasks and chips are getting smaller and smaller, and the requirement for the ability to remove micro-particles smaller than 100 nm is also higher. However, it is very difficult to remove particles smaller than 100 nm. One reason is that the adhesion force between the particle and the surface is the van der Waals force F v , which is proportional to the size d of the particle (F v ∝d), and the fluid drag force F d for carrying away the particle is proportional to the square of the particle size d and the square of the flow velocity u (F d ∝d 2 u 2 ). Therefore, when the particle is smaller, the fluid drag force will become smaller, and a faster flow velocity is required to generate enough drag force to carry away the particle. However, too fast a flow velocity may cause damage to the pattern. Another reason is that there is a stagnant layer between the fluid and the object surface, and the flow velocity of the liquid in it is very slow. The thickness of the stagnant layer of water is about 100 nm, so it is difficult to remove particles smaller than 100 nm.

[0003] Currently, the commonly used cleaning methods include megasonic cleaning and wet chemical cleaning. Megasonic cleaning uses sound waves with a frequency of 0.8 - 2 Mega Hz. Its oscillation will cause cavitation in water, generating countless micro-bubbles. When these bubbles burst, they generate pressure to peel off the particles / dirt on the surface. As the pattern size on the substrate gets smaller and smaller, it becomes more fragile, and the pressure generated when the bubbles burst may damage the pattern itself. Wet chemical cleaning uses various chemicals, such as sulfuric acid, ammonia water, hydrogen peroxide, etc. to achieve various cleaning effects, such as dissolving particles / dirt, changing the surface affinity to make particles / dirt easily fall off, and corroding the oxide layer on the surface to make particles / dirt fall off, etc. However, the chemicals may cause reactions with the materials on the substrate, resulting in changes in the pattern size or residues of chemical ions, etc. Summary of the Invention

[0004] In view of this, embodiments of the present application provide a freezing cleaning method and device for removing micro-particles, which at least partially solve the problem of damage to the pattern on the substrate caused by the cleaning method in the prior art.

[0005] In a first aspect, embodiments of the present application provide a freezing cleaning method for removing micro-particles, and the method includes:

[0006] Cooling the substrate to be cleaned to a certain temperature;

[0007] Spraying ultrapure deionized water on the substrate to be cleaned to form a water film;

[0008] The particles begin to freeze first to form ice particles, and the ice particles float up and leave the retention layer;

[0009] Ultrapure deionized water is sprayed to melt the ice particles and the substrate to be cleaned is spin-dried.

[0010] According to a specific implementation of the embodiment of the present application, the cooling temperature range of the substrate to be cleaned is minus 20 degrees to minus 40 degrees.

[0011] According to a specific implementation of the embodiment of the present application, the substrate to be cleaned is cooled using nitrogen.

[0012] According to a specific implementation of the embodiment of the present application, during the process of spraying ultrapure deionized water to melt the ice particles, the temperature range of the ultrapure deionized water is 15° C.-25° C.

[0013] According to a specific implementation of the embodiment of the present application, after the step of spraying ultrapure deionized water to melt the ice particles and spinning the substrate to be cleaned, the step further includes:

[0014] Performing cleanliness detection on the substrate to be cleaned;

[0015] If the cleanliness requirement is not met, repeat the freezing cleaning process until the cleanliness requirement is met.

[0016] In a second aspect, an embodiment of the present application further provides a freezing cleaning device for removing tiny particles, which is applied to the freezing cleaning method for removing tiny particles as described in any embodiment of the first aspect above, and the device comprises:

[0017] A rotatable platform for carrying the substrate to be cleaned;

[0018] A cooling component is disposed in the rotatable platform and is located below the substrate to be cleaned, and the cooling component is used to cool the substrate to be cleaned;

[0019] The movable arm is located above the rotatable platform. The movable arm is provided with a nozzle. The spraying direction of the nozzle is toward the substrate to be cleaned. The movable arm drives the nozzle to spray ultrapure deionized water on the substrate to be cleaned.

[0020] According to a specific implementation of the embodiment of the present application, a thermometer is also provided on the movable arm, and the thermometer is used to monitor the surface temperature of the substrate to be cleaned.

[0021] According to a specific implementation manner of an embodiment of the present application, the cooling member is a nitrogen pipeline, and the nitrogen pipeline is used to introduce nitrogen to cool the substrate to be cleaned.

[0022] Beneficial effects

[0023] In the freezing cleaning method in the embodiment of the present application, the principle that the volume of water becomes larger and the density becomes smaller after freezing is used to generate buoyancy to carry the particles away from the stagnant layer to remove the particulate matter, increasing the cleaning efficiency for micro-particles smaller than 100 nm; the method of the present application does not damage the fine patterns on the substrate; no chemicals are used, there is no pollution problem and it has the advantage of low cost. Description of the drawings

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0025] Figure 1 It is a schematic diagram of a freezing cleaning method for removing micro-particles according to an embodiment of the present invention;

[0026] Figure 2 It is a structural diagram of a freezing cleaning device for removing micro-particles according to an embodiment of the present invention.

[0027] In the figure: 1, a rotatable platform; 2, a substrate to be cleaned; 3, a movable arm; 4, a nozzle; 5, a cooling member; 6, a thermometer. Specific implementation manners

[0028] The embodiments of the present application will be described in detail below with reference to the drawings.

[0029] The following illustrates the implementation manners of the present application through specific specific examples. Those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts belong to the scope of protection of the present application.

[0030] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0031] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0032] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects described may be practiced without these specific details.

[0033] On the first aspect, the embodiments of the present application provide a freezing cleaning method for removing tiny particles, which uses the physical properties of water to achieve the effect of removing particles. Ultra-pure deionized water is poured onto the surface of a substrate that has been pre-cooled to a low temperature to form a water film. Because water needs ice nuclei to freeze, the water will first cover the particles and begin to freeze. Since the density of ice is smaller than that of water, the ice will float up and leave the retention layer with the particles, and then the ice will melt and then be rinsed to take the particles away.

[0034] Specifically, refer to Figure 1 , the freezing cleaning method comprises the following steps:

[0035] Step 1: Cool the substrate to be cleaned to a certain temperature. The cooling temperature range is -20 degrees Celsius to -40 degrees Celsius. The substrate to be cleaned can be cooled by low-temperature nitrogen, but the cooling method of the substrate to be cleaned is not limited to that listed in this embodiment.

[0036] Step 2: Spray ultrapure deionized water on the substrate to be cleaned to form a water film. During the spraying process, try to ensure the uniformity of the spraying, and the water flow rate during spraying should not be too fast. Too much impact may damage the pattern. The specific water flow rate is set according to the substrate to be cleaned.

[0037] Step 3: The particles begin to freeze first to form ice particles, and the ice particles float up and leave the retention layer. Since water needs ice nuclei to freeze, on the surface of the substrate, water will first cover the particles and begin to freeze. Since the density of ice is smaller than that of water, the ice particles will float up and leave the retention layer. If the temperature is low enough, the entire surface of the substrate to be cleaned will freeze.

[0038] Step 4: Spray ultrapure deionized water to melt the ice particles and spin dry the substrate to be cleaned. In this step, the particles are wrapped in ice and separated from the retention layer. At this time, there is no restriction of the retention layer when removing the tiny particles. Therefore, spray ultrapure deionized water to melt the ice on the surface of the substrate to be cleaned and rotate the substrate to be cleaned at the same time. Since the ice will melt from the upper layer, the water will carry away the particles during rotation. Since the ice needs to be melted, the temperature range of the ultrapure deionized water is 15℃-25℃.

[0039] It needs to be explained that for particles to be able to escape from the retention layer, two conditions must be met. First, the buoyancy generated by ice must be greater than the sum of the gravity of the particles plus ice particles and the adhesion between the particles and the substrate surface; second, the particles must be able to freeze first. There is some uncertainty here. For ice to freeze, there must be ice nuclei, that is, there must be tiny particles as ice attachments. Therefore, the added water must be ultra-pure deionized water, and try to ensure that the freezing starts from the particles. It cannot be ruled out that the freezing will start from the small patterns on the photomask, so it is necessary to repeat many times to increase the particle removal rate.

[0040] Therefore, after step 4, the following steps are also included:

[0041] Step 5: performing cleanliness detection on the substrate to be cleaned;

[0042] Step 6: If the cleanliness does not meet the requirements, repeat the freezing and cleaning process until the cleanliness requirements are met.

[0043] In the second aspect, the present application also provides a freezing cleaning device for removing tiny particles, which is applied to the freezing cleaning method for removing tiny particles as described in any embodiment of the first aspect above. Figure 1, the device includes a rotatable platform 1, a cooling member 5, a movable arm 3 and a nozzle 4. The rotatable platform 1 is used to carry the substrate 2 to be cleaned, and the rotatable platform 1 can drive the substrate 2 to be cleaned to rotate. On the one hand, it is beneficial to make the spraying more uniform during spraying. On the other hand, when removing particles, it rotates quickly to spin dry the water on the surface of the substrate; the cooling member 5 is arranged inside the rotatable platform 1 and below the substrate 2 to be cleaned, and the cooling member 5 is used to cool the substrate 2 to be cleaned; the movable arm 3 is located above the rotatable platform 1, and a nozzle 4 is provided on the movable arm 3. The spraying direction of the nozzle 4 faces the substrate 2 to be cleaned, and the movable arm 3 drives the nozzle 4 to spray ultrapure deionized water on the substrate 2 to be cleaned.

[0044] Preferably, a thermometer 6 is further provided on the movable arm 3, and the thermometer 6 is used to monitor the surface temperature of the substrate 2 to be cleaned.

[0045] Further, the cooling member 5 is a nitrogen gas pipeline, and the nitrogen gas pipeline is used to introduce low-temperature nitrogen gas to cool the substrate 2 to be cleaned. The temperature of the low-temperature nitrogen gas needs to meet the requirement of cooling the substrate 2 to be cleaned to minus 20 degrees to minus 40 degrees.

[0046] The freezing cleaning method for removing micro-particles in this application has a small physical impact force and does not damage the pattern; there is no consumption of chemicals, the cost is relatively low, and there will be no change in the pattern size or the influence of chemical ion residues.

[0047] The above is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in this application should be covered within the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

1. A cryogenic cleaning method for removing fine particles, characterized in that, The method comprises: Cooling the substrate to be cleaned to a certain temperature, wherein the temperature range of the substrate to be cleaned is from -20 degrees Celsius to -40 degrees Celsius; Spraying ultrapure deionized water on the cooled substrate to be cleaned to form a water film, so that the water film begins to freeze first at the location where the particles exist to form ice particles, thereby making use of the physical principle that the density of ice is smaller than that of water to make the ice particles float up in the water film and leave the retention layer; Ultrapure deionized water is sprayed to melt the ice particles and the substrate to be cleaned is spun dry. During the process of spraying ultrapure deionized water to melt the ice particles, the temperature of the ultrapure deionized water is in the range of 15°C-25°C. As the ice melts from the upper layer, the water removes the particles when rotating.

2. The cryogenic cleaning method for removing fine particles according to claim 1, characterized in that, The substrate to be cleaned is cooled by nitrogen.

3. The cryogenic cleaning method for removing fine particles according to claim 1, characterized in that, After the step of spraying ultrapure deionized water to melt the ice particles and spinning the substrate to be cleaned, the step further includes: Performing cleanliness detection on the substrate to be cleaned; If the cleanliness requirement is not met, repeat the freezing cleaning process until the cleanliness requirement is met.

4. A cryogenic cleaning device for removing fine particles, characterized in that, The freezing and cleaning method for removing tiny particles according to any one of claims 1 to 3, wherein the device comprises: A rotatable platform for carrying the substrate to be cleaned; A cooling component is disposed in the rotatable platform and is located below the substrate to be cleaned, and the cooling component is used to cool the substrate to be cleaned; The movable arm is located above the rotatable platform. The movable arm is provided with a nozzle. The spraying direction of the nozzle is toward the substrate to be cleaned. The movable arm drives the nozzle to spray ultrapure deionized water on the substrate to be cleaned.

5. The cryogenic cleaning device for removing fine particles according to claim 4, characterized in that, The movable arm is also provided with a thermometer, and the thermometer is used to monitor the surface temperature of the substrate to be cleaned.

6. The cryogenic cleaning device for removing fine particles according to claim 4, characterized in that, The cooling component is a nitrogen pipeline, and the nitrogen pipeline is used to pass nitrogen to cool the substrate to be cleaned.

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