Wafer cleaning method and device

Abstract

The invention discloses a wafer cleaning method and a wafer cleaning device. According to one embodiment of the invention, the wafer cleaning method comprises the following steps: cleaning a wafer by using a micro-nano bubble cleaning liquid, and forming a micro-nano bubble cleaning liquid film on the wafer; using a supersonic / megasonic device to transmit acoustic energy to the liquid film to clean the wafer; and drying the wafer. According to the wafer cleaning method and device, the wafer is cleaned by adopting the micro-nano bubble cleaning solution, and the wafer is cleaned in combination with ultrasonic / megasonic waves, so that the wafer cleaning effect is improved, the cleaning capacity of the cleaning solution is improved, the use of chemical liquid medicine is reduced or even avoided while pollutants on the wafer are removed, the production cost can be saved, and the environmental pollution can be effectively reduced.

Description

Technical Field

[0001] The present application relates to the field of wafer cleaning, and in particular to a wafer cleaning method and device. Background Art

[0002] Wafer cleaning is a key step in integrated circuit manufacturing. As device feature sizes continue to shrink, not only is the number of cleaning steps increasing, but more stringent requirements are placed on the tolerable size and number of particles on the wafer surface, and therefore the requirements for cleaning technology are becoming increasingly demanding.

[0003] Wet cleaning is the main method of wafer cleaning at present. Chemical liquid is often used in the wet cleaning process to achieve the purpose of cleaning through chemical reaction. It has achieved good results, but it also brings at least the following problems:

[0004] 1. The chemical liquids commonly used in wet cleaning are usually strong acids and strong oxidizing chemical liquids, which will cause certain safety hazards during transportation and large-scale use;

[0005] 2. The residual chemical solution will cause a loss in the yield of the wafer. Therefore, after using the chemical solution to remove the contaminants on the wafer, a large amount of ultrapure water will be used to rinse to remove the residual chemical solution, which also causes a waste of water resources;

[0006] 3. It is usually difficult to treat the waste liquid after using a large amount of chemical liquid, which can easily cause environmental pollution problems.

[0007] Therefore, developing new wafer cleaning technologies to reduce the use of chemical solutions is of great significance for saving integrated circuit manufacturing costs and reducing environmental pollution. Summary of the invention

[0008] The present application aims to propose a new wafer cleaning method and device to reduce the use of chemical solutions, reduce the cost of integrated circuit manufacturing, and reduce environmental pollution.

[0009] According to an embodiment of the present application, a wafer cleaning method is provided, comprising:

[0010] Cleaning the wafer using a micro-nano bubble cleaning solution and forming a micro-nano bubble cleaning solution film on the wafer;

[0011] Using an ultrasonic / megasonic device to transmit acoustic energy to the liquid film to clean the wafer;

[0012] The wafer is dried.

[0013] According to another embodiment of the present application, a wafer cleaning method is provided, comprising:

[0014] Applying liquid to the wafer to form a liquid film on the wafer, and using an ultrasonic / megasonic device to transmit acoustic energy to the liquid film to clean the wafer;

[0015] Use micro-nano bubble cleaning fluid to clean the wafer;

[0016] The wafer is dried.

[0017] According to an embodiment of the present application, a wafer cleaning device is provided, comprising:

[0018] A wafer clamp for holding the wafer;

[0019] A micro-nano bubble cleaning liquid generating device is used to generate micro-nano bubble cleaning liquid and provide the micro-nano bubble cleaning liquid to the wafer to form a micro-nano bubble cleaning liquid film on the wafer;

[0020] An ultrasonic / megasonic device for transmitting acoustic energy to the liquid film to clean the wafer;

[0021] A drying device is used to dry the wafer.

[0022] According to another embodiment of the present application, a wafer cleaning device is provided, comprising:

[0023] A wafer clamp for holding the wafer;

[0024] A micro-nano bubble cleaning liquid generating device, used for generating micro-nano bubble cleaning liquid and providing the micro-nano bubble cleaning liquid to the wafer to clean the wafer;

[0025] A nozzle, used for applying liquid to the wafer and forming a liquid film on the wafer;

[0026] An ultrasonic / megasonic device for transmitting acoustic energy to the liquid film to clean the wafer;

[0027] A drying device is used to dry the wafer.

[0028] The present application utilizes the physical and chemical properties of micro-nano bubbles, adopts a micro-nano bubble cleaning liquid generating device to generate micro-nano bubble cleaning liquid for cleaning wafers, and combines ultrasonic / megasonic waves to clean the wafers, thereby improving the wafer cleaning effect and the cleaning ability of the cleaning liquid, while removing contaminants on the wafer and reducing or even avoiding the use of chemical solutions.

[0029] Details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0031] Figure 1 is a flow chart of a wafer cleaning method according to a first embodiment of the present application;

[0032] Figure 2 is a flow chart of a wafer cleaning method according to a second embodiment of the present application;

[0033] Figure 3 is a schematic structural diagram of a wafer cleaning device according to a third embodiment of the present application; and

[0034] Figure 4 It is a schematic structural diagram of a wafer cleaning device according to the fourth embodiment of the present application. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for ordinary technicians in the field related to the contents disclosed in the present application, some changes such as design, manufacturing or production based on the technical contents disclosed in the present application are only conventional technical means, and should not be understood as insufficient contents disclosed in the present application.

[0036] Embodiment 1

[0037] Figure 1 1 is a flow chart of a wafer cleaning method according to an embodiment of the present application. Figure 1 As shown, the wafer cleaning method comprises the following steps:

[0038] Step S101 , cleaning a wafer with a micro-nano bubble cleaning solution and forming a liquid film of the micro-nano bubble cleaning solution on the wafer.

[0039] Micro-nano bubbles are bubbles with diameters ranging from tens of nanometers to hundreds of micrometers. Compared with conventional bubbles, micro-nano bubbles have the following physical and chemical properties:

[0040] Characteristic 1: Micro-nano bubbles have a large specific surface area and extraordinary gas solubility, which can easily promote the reaction speed between gas and liquid;

[0041] Feature 2: Micro-nano bubbles shrink by themselves, and their size is very small, so they can penetrate into the surface of complex structures;

[0042] Feature 3: Micro-nano bubbles themselves carry negative charges and can combine with pollutants through electrostatic attraction, thereby cleaning the pollutants from the surface of objects. Micro-nano bubble cleaning is a physical cleaning method that does not require any chemical reagents.

[0043] Step S102 , using an ultrasonic / megasonic device to transmit acoustic energy to a micro-nano bubble cleaning liquid film on the wafer to clean the wafer.

[0044] Step S103, drying the wafer.

[0045] In step S103 , a dry gas may be sprayed toward the wafer to dry the wafer.

[0046] In this embodiment, by applying micro-nano bubble cleaning to the field of wafer cleaning, it is possible to reduce or even avoid the use of chemical solutions while cleaning pollutants on the wafer, which helps to save production costs and effectively reduce environmental pollution.

[0047] In some embodiments, the step of using an ultrasonic / megasonic device to transmit acoustic energy to a micro-nano bubble cleaning liquid film on a wafer to clean the wafer includes: using TEBO megasonic waves to clean the wafer, wherein the TEBO megasonic waves are generated by a sequential energy-induced cavitation oscillation method, and the sequential energy-induced cavitation oscillation method forces bubbles to oscillate in a specific size and shape through rapid pressure changes, thereby precisely controlling the cavitation of the bubbles and avoiding damage to the graphic structure on the wafer.

[0048] In traditional ultrasonic or megasonic assisted wet cleaning, the pattern structure on the wafer is easily damaged by the microjet shock wave generated by the instantaneous cavitation explosion of bubbles. To solve this problem, a new ultrasonic cleaning technology called Timely Energized Bubble Oscillation (TEBO) has emerged. This technology can clean wafers with pattern structures without damaging the pattern structures. The principle of this technology is to use a series of rapid pressure changes (for example, a frequency of one million times per second or other times) to force bubbles to oscillate in a specific size and shape, and to accurately and multi-parameterly control the cavitation of bubbles during megasonic cleaning, thereby avoiding pattern damage caused by instantaneous cavitation in traditional ultrasonic or megasonic cleaning, and cleaning the wafer without damage.

[0049] Therefore, in this embodiment, by using micro-nano bubble cleaning liquid to clean the wafer and combining it with TEBO megasonic waves, it is possible to improve the efficiency of particle removal on the wafer surface, reduce the amount of chemical liquid used, and reduce damage to wafers with graphic structures.

[0050] Specifically, the TEBO megasonic wave technology can refer to the prior patent WO2019095126A1. The "semiconductor wafer cleaning damage control method" described in the patent can be understood as the TEBO megasonic wave technology in this application.

[0051] In some embodiments, the step of using an ultrasonic / megasonic device to transfer acoustic energy to a micro-nano bubble cleaning liquid film on a wafer to clean the wafer includes: using SAPS megasonic waves to clean the wafer, wherein the SAPS megasonic waves are generated by a spatial alternating phase shift method, and the spatial alternating phase shift method is to use a megasonic wave generator and utilize the spatial alternating phase shift of the megasonic waves to provide megasonic wave energy to a flat plate or a wafer with a patterned structure in a highly uniform manner, thereby effectively removing random defects on the entire wafer.

[0052] In traditional ultrasonic or megasonic cleaning processes, the wafer warping caused by stress after different processes makes it impossible to achieve uniform distribution of acoustic wave energy on the wafer surface. In order to solve this problem, a new acoustic cleaning technology called Space Alternative Phase Shift (SAPS) has emerged, which can clean wafers without graphic structures. The principle of this technology is to use a megasonic generator and utilize the spatial alternating phase shift of megasonic waves to provide megasonic energy to the surface of a flat plate or a wafer with a graphic structure in a highly uniform manner at the microscopic level, effectively removing random defects on the entire wafer and reducing the use of chemicals.

[0053] Specifically, the SAPS megasonic wave technology can refer to the prior patent WO2010066081, and the "method and apparatus for cleaning semiconductor wafers" described in the patent can be understood as the SAPS megasonic wave technology in the present application.

[0054] In this embodiment, micro-nano bubble cleaning liquid is used to clean the wafer, and then combined with SAPS megasonic waves, so that the wafer surface can obtain uniform megasonic wave energy density, thereby improving the particle removal efficiency on the wafer surface, reducing the use of chemical solutions, and reducing damage to wafers with graphic structures.

[0055] Before step S103 , the following step may also be included: using deionized water or carbon dioxide deionized water to clean the surface of the wafer to remove pollutants on the surface of the wafer.

[0056] In some embodiments, the micro-nano bubble cleaning liquid in step S101 may be generated by passing compressed gas and cleaning liquid into a micro-nano bubble cleaning liquid generating device to generate the micro-nano bubble cleaning liquid.

[0057] In this embodiment, the cleaning liquid can be ultrapure water. By passing compressed gas and ultrapure water into a micro-nano bubble cleaning liquid generating device to generate a micro-nano bubble cleaning liquid, it is possible to avoid using chemical liquids to clean the wafers, which helps save production costs and effectively reduce environmental pollution. In other embodiments, the cleaning liquid can also be a chemical liquid. By passing compressed gas and chemical liquid into a micro-nano bubble cleaning liquid generating device to generate a micro-nano bubble cleaning liquid, the micro-nano bubbles and chemical liquid are used in combination, which can improve the cleaning ability of the chemical liquid and reduce the amount of chemical liquid used.

[0058] In this embodiment, micro-nano bubbles can be generated by the Venturi effect. Therefore, the micro-nano bubble cleaning liquid generating device in this embodiment can be a Venturi tube type micro-nano bubble cleaning liquid generating device. The Venturi tube type micro-nano bubble cleaning liquid generating device uses the special structure of the Venturi tube that first contracts and then expands when the high-speed liquid flows through the venturi tube, and continuously converts the dynamic pressure and static pressure, thereby generating strong turbulent shear. The large bubbles in the low-pressure area of ​​the throat are sheared and broken multiple times to finally form micro-nano bubbles. Compared with other micro-nano bubble generation methods, this method has the characteristics of simple process, convenient operation and easy to achieve engineering scale-up.

[0059] In some embodiments, the micro-nano bubble cleaning solution can also be generated by ultrasonic cavitation, chemical reaction, electrolysis, dissolved gas precipitation, gas shearing, etc.

[0060] Before step S101, it is also possible to detect whether the bubble size in the micro-nano bubble cleaning liquid is within a preset size range. When it is detected that the bubble size is not within the preset size range, the flow rate of the compressed gas and / or the flow rate of the cleaning liquid is adjusted so that the bubble size in the micro-nano bubble cleaning liquid is within the preset size range. The average bubble diameter increases with the increase of the gas volume and decreases with the increase of the liquid volume.

[0061] In this embodiment, the bubble size in the micro-nano bubble cleaning solution is controlled by adjusting the flow rate of compressed gas and / or the flow rate of cleaning solution, so as to realize the generation of micro-nano bubbles of specific size according to different requirements. In addition, by supplying the micro-nano bubble cleaning solution with micro-nano bubbles of specific size to the wafer, the contaminants in the complex graphic structure on the wafer can be removed by utilizing the small volume of micro-nano bubbles to easily reach the surface of the complex graphic structure and the electrostatic attraction of the micro-nano bubbles to absorb impurities.

[0062] Embodiment 2

[0063] The present application also provides a wafer cleaning method. Figure 2 1 is a flow chart of a wafer cleaning method according to an embodiment of the present application. The wafer cleaning method comprises the following steps:

[0064] Step S201, applying liquid to the wafer to form a liquid film on the wafer, and using an ultrasonic / megasonic device to transmit acoustic energy to the liquid film to clean the wafer;

[0065] Step S202, cleaning the wafer using a micro-nano bubble cleaning solution;

[0066] Step S203, drying the wafer.

[0067] In step S201, applying liquid to the wafer may be applying chemical reagents or deionized water to the wafer. Using an ultrasonic / megasonic device to clean the wafer may be using TEBO megasonic waves to clean the wafer as described in the first embodiment or using SAPS megasonic waves to clean the wafer.

[0068] Before step S203, the following step may also be included: using deionized water or carbon dioxide deionized water to clean the surface of the wafer to remove pollutants on the surface of the wafer.

[0069] The method for generating the micro-nano bubble cleaning liquid in this embodiment and the method for detecting and adjusting the bubble size in the micro-nano bubble cleaning liquid can refer to the example described in the above-mentioned embodiment 1, and this embodiment will not be repeated here.

[0070] In this embodiment, step S201 and step S202 may be performed alternately for a preset number of times according to process requirements to improve the wafer cleaning effect.

[0071] Embodiment 3

[0072] The present application embodiment provides a wafer cleaning device, which can execute the wafer cleaning method in the above embodiment 1, such as Figure 3 As shown, the device comprises:

[0073] A wafer clamp 31 for clamping a wafer 35;

[0074] A micro-nano bubble cleaning liquid generating device 32 is used to generate a micro-nano bubble cleaning liquid and provide the micro-nano bubble cleaning liquid to a wafer 35 to form a micro-nano bubble cleaning liquid film 38 on the wafer 35;

[0075] Ultrasonic / megasonic device 33, used to transmit acoustic energy to liquid film 38 to clean wafer 35;

[0076] The drying device 34 is used to dry the wafer 35 .

[0077] In some embodiments, the wafer cleaning device further includes a rotating mechanism 36 for driving the wafer 35 to rotate.

[0078] In some embodiments, the micro-nano bubble cleaning liquid generating device 32 comprises:

[0079] A micro-nano bubble generator 322, used to generate a micro-nano bubble cleaning solution;

[0080] The outlet 321 connected to the micro-nano bubble generator 322 is used to supply the micro-nano bubble cleaning liquid to the surface of the wafer 35 to clean the wafer 35 .

[0081] Embodiment 4

[0082] The present application also provides a wafer cleaning device, which can execute the wafer cleaning method in the above-mentioned embodiment 2. Figure 4 As shown, the device comprises:

[0083] A wafer clamp 41 for clamping a wafer 45;

[0084] A micro-nano bubble cleaning liquid generating device 42, used for generating micro-nano bubble cleaning liquid and providing the micro-nano bubble cleaning liquid to the wafer 45 to clean the wafer 45;

[0085] a nozzle 47 for applying liquid onto the wafer 45 and forming a liquid film 48 on the wafer 45;

[0086] Ultrasonic / megasonic wave device 43, used to transmit acoustic energy to liquid film 48 to clean wafer 45;

[0087] The drying device 44 is used to dry the wafer 45 .

[0088] In some embodiments, the wafer cleaning device further includes a rotating mechanism 46 for driving the wafer 45 to rotate.

[0089] In some embodiments, the micro-nano bubble cleaning liquid generating device 42 comprises:

[0090] A micro-nano bubble generator 422, used to generate a micro-nano bubble cleaning solution;

[0091] The outlet 421 connected to the micro-nano bubble generator 422 is used to supply the micro-nano bubble cleaning liquid to the surface of the wafer 45 to clean the wafer 45 .

[0092] Those skilled in the art should understand that the technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0093] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A wafer cleaning method, characterized in that: include: Cleaning the wafer using a micro-nano bubble cleaning solution and forming a micro-nano bubble cleaning solution film on the wafer; Using an ultrasonic / megasonic device to transmit acoustic energy to the liquid film to clean the wafer; The wafer is dried.

2. The wafer cleaning method according to claim 1, characterized in that: The step of using an ultrasonic / megasonic device to transmit acoustic energy to the liquid film to clean the wafer includes: using TEBO megasonic waves to clean the wafer, wherein the TEBO megasonic waves are generated by a sequential energy-induced cavitation oscillation method, and the sequential energy-induced cavitation oscillation method forces bubbles to oscillate in a specific size and shape through rapid pressure changes, thereby accurately controlling the cavitation of the bubbles and avoiding damage to the graphic structure on the wafer.

3. The wafer cleaning method according to claim 1, characterized in that: The step of using an ultrasonic / megasonic device to transfer acoustic energy to the liquid film to clean the wafer includes: using SAPS megasonic waves to clean the wafer, wherein the SAPS megasonic waves are generated by a spatial alternating phase shift method, and the spatial alternating phase shift method is to use a megasonic wave generator and utilize the spatial alternating phase shift of megasonic waves to provide megasonic wave energy to the wafer in a highly uniform manner, thereby effectively removing random defects on the entire wafer.

4. The wafer cleaning method according to claim 1, characterized in that: Before drying the wafer, the method further comprises: Rinse the wafer using deionized water or carbon dioxide deionized water.

5. The wafer cleaning method according to claim 1, characterized in that: The method for generating the micro-nano bubble cleaning solution includes: The compressed gas and the cleaning liquid are introduced into a micro-nano bubble cleaning liquid generating device to generate the micro-nano bubble cleaning liquid.

6. The wafer cleaning method according to claim 5, characterized in that: The cleaning liquid includes ultrapure water or chemical liquid.

7. The wafer cleaning method according to claim 5, characterized in that: Before cleaning the wafer with the micro-nano bubble cleaning solution, the method further includes: Detecting whether the bubble size in the micro-nano bubble cleaning solution is within a preset size range; When it is detected that the bubble size is not within the preset size range, the flow rate of the compressed gas and / or the flow rate of the cleaning liquid is adjusted so that the bubble size in the micro-nano bubble cleaning liquid is within the preset size range.

8. A wafer cleaning method, characterized in that: include: Applying liquid to the wafer to form a liquid film on the wafer, and using an ultrasonic / megasonic device to transmit acoustic energy to the liquid film to clean the wafer; Use micro-nano bubble cleaning fluid to clean the wafer; The wafer is dried.

9. The wafer cleaning method according to claim 8, characterized in that: The steps of applying liquid to the wafer and forming a liquid film on the wafer, and using an ultrasonic / megasonic device to transmit acoustic energy to the liquid film to clean the wafer include: using TEBO megasonic waves to clean the wafer, wherein the TEBO megasonic waves are generated by a sequential energy-induced cavitation oscillation method, and the sequential energy-induced cavitation oscillation method forces bubbles to oscillate in a specific size and shape through rapid pressure changes, thereby accurately controlling the cavitation of the bubbles and avoiding damage to the graphic structure on the wafer.

10. The wafer cleaning method according to claim 8, characterized in that: The steps of applying liquid to the wafer and forming a liquid film on the wafer, and using an ultrasonic / megasonic device to transfer acoustic energy to the liquid film to clean the wafer include: using SAPS megasonic waves to clean the wafer, wherein the SAPS megasonic waves are generated by a spatial alternating phase shift method, and the spatial alternating phase shift method is to use a megasonic wave generator and utilize the spatial alternating phase shift of the megasonic waves to provide megasonic wave energy to the wafer in a highly uniform manner, thereby effectively removing random defects on the entire wafer.

11. The wafer cleaning method according to claim 8, characterized in that: Before drying the wafer, the method further comprises: Rinse the wafer using deionized water or carbon dioxide deionized water.

12. The wafer cleaning method according to claim 8, characterized in that: The method for generating the micro-nano bubble cleaning solution includes: The compressed gas and the cleaning liquid are introduced into a micro-nano bubble cleaning liquid generating device to generate the micro-nano bubble cleaning liquid.

13. The wafer cleaning method according to claim 12, characterized in that: The cleaning liquid includes ultrapure water or chemical liquid.

14. The wafer cleaning method according to claim 12, characterized in that: Before cleaning the wafer with the micro-nano bubble cleaning solution, the method further includes: Detecting whether the bubble size in the micro-nano bubble cleaning solution is within a preset size range; When it is detected that the bubble size is not within the preset size range, the flow rate of the compressed gas and / or the flow rate of the cleaning liquid is adjusted so that the bubble size in the micro-nano bubble cleaning liquid is within the preset size range.

15. The wafer cleaning method according to claim 8, characterized in that: The steps of applying liquid to the wafer to form a liquid film on the wafer, using an ultrasonic / megasonic device to transmit acoustic energy to the liquid film to clean the wafer and the step of using a micro-nano bubble cleaning liquid to clean the wafer are alternately performed a preset number of times.

16. A wafer cleaning device, characterized in that: include: A wafer clamp for holding the wafer; A micro-nano bubble cleaning liquid generating device is used to generate micro-nano bubble cleaning liquid and provide the micro-nano bubble cleaning liquid to the wafer to form a micro-nano bubble cleaning liquid film on the wafer; An ultrasonic / megasonic device for transmitting acoustic energy to the liquid film to clean the wafer; A drying device is used to dry the wafer.

17. A wafer cleaning device, characterized in that: include: A wafer clamp for holding the wafer; A micro-nano bubble cleaning liquid generating device, used for generating micro-nano bubble cleaning liquid and providing the micro-nano bubble cleaning liquid to the wafer to clean the wafer; A nozzle, used for applying liquid to the wafer and forming a liquid film on the wafer; An ultrasonic / megasonic device for transmitting acoustic energy to the liquid film to clean the wafer; A drying device is used to dry the wafer.

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