Method for removing silicon dust residues on surface of wafer

Abstract

The invention discloses a method for removing silicon chip residues on the surface of a wafer. The method comprises the steps that S1, the wafer subjected to edge cutting process treatment is provided; s2, spraying ozone water to the wafer through a first nozzle to wash the surface of the wafer; s3, cleaning liquid is sprayed to the wafer through a second nozzle so as to wash the surface of the wafer, and the cleaning liquid is deionized water with the resistivity not larger than 0.7 Mohm.cm; s4, spraying a second fluid to the wafer by using a third nozzle so as to wash the surface of the wafer; and S5, transferring the cleaned wafer into a wafer conveying box. According to the technical scheme, residual silicon chips on the surface of the wafer after the edge cutting process can be effectively removed.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor manufacturing, and specifically to a method for removing silicon scraps residue from the surface of a wafer. Background Art

[0002] BSI technology optimizes the light transmission path by placing photosensitive elements on the back of the wafer, improves the sensitivity, signal-to-noise ratio and image quality of the image sensor, and can meet the needs of different application scenarios for high-quality images, thus becoming an important development direction for image sensors. Among them, the edge trimming process can remove possible defects and contamination at the edge of the wafer, which is beneficial to the bonding and thinning process of the back-end wafer, improves the quality and stability of the BSI wafer, and ensures the performance and reliability of the final product.

[0003] In the edge trimming process, the water infiltration state of the wafer surface is first ensured, and the edge is trimmed with a grinder, and then the back and surface of the wafer are cleaned to remove the residual silicon chips. However, in the actual production process, due to the large amount of silicon chips generated by edge trimming, it is difficult to effectively remove them in the subsequent cleaning process, resulting in silicon chips remaining on the wafer surface. These residual silicon chips will cause bubbles to appear in the subsequent bonding and break during the thinning process, greatly affecting the yield of the wafer product. Summary of the invention

[0004] In order to solve the problems in the related art, the present application provides a method for removing silicon chips residue on the surface of a wafer.

[0005] The present application provides a method for removing silicon chips residue on the surface of a wafer, comprising: S1: Provide wafers after edge cutting process; S2: spraying ozone water toward the wafer through a first nozzle to rinse the surface of the wafer; S3: spraying a cleaning liquid toward the wafer through a second nozzle to rinse the surface of the wafer, wherein the cleaning liquid is deionized water having a resistivity of no more than 0.7 Mohm·cm; S4: using a third nozzle to spray two fluids toward the wafer to flush the surface of the wafer; S5: Transferring the cleaned wafer to a wafer transfer box.

[0006] In some embodiments, before S1, the method further includes: By adjusting the concentration of carbon dioxide, the resistivity of the cleaning liquid is adjusted to no more than 0.7 Mohm·cm; The cleaning fluid is sprayed using the second nozzle for a predetermined period of time to ensure that the resistivity of the cleaning fluid in the pipeline connected to the second nozzle is stable.

[0007] In some embodiments, the predetermined duration is no less than 15 minutes.

[0008] In some embodiments, in S4, the angular velocity of the rotation of the third nozzle is 0.3° / s.

[0009] In some embodiments, the second fluid is deionized water carrying nitrogen.

[0010] The technical solution of this application has at least the following advantages: 1. By setting the cleaning liquid to deionized water with a resistivity of no more than 0.7 Mohm·cm, when the cleaning liquid is used to clean the wafer with silicon chips remaining on the surface, the electronegativity of the residual silicon chips can be effectively neutralized, and the adsorption capacity of the silicon chips on the positively charged silicon nitride surface can be weakened, thereby improving the cleaning effect of the silicon chips and effectively removing the silicon chips remaining on the wafer surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0012] Figure 1 It is a flow chart of a method for removing silicon chips residue from a wafer surface provided by an exemplary embodiment of the present application.

[0013] Figure 2-1 It is a defect distribution diagram of a wafer before using the method, provided by an exemplary embodiment of the present application; Figure 2-2 It is a defect distribution diagram of a wafer after using the method, provided by an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0014] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0015] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0016] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0017] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0018] The present application provides a method for removing silicon chips residue on the surface of a wafer, which is mainly used to clean a wafer that has undergone an edge cutting process. Figure 1 , the method comprises the following steps: S1: Provide a wafer after edge cutting process.

[0019] Exemplarily, a wafer is provided, the wafer comprising a substrate and a silicon nitride layer formed on a surface of the substrate. In order to remove possible defects and contamination at the edge of the wafer, the wafer surface is first trimmed by an edge cutting process, during which silicon chips remain on the wafer surface.

[0020] S2: Spray ozone water toward the wafer through the first nozzle to rinse the wafer surface.

[0021] For example, ozone water is first sprayed onto the surface of the wafer through the first nozzle to clean the organic pollutants attached to the front and back of the wafer. The duration of this step can be specifically set according to the specifications of the wafer or the process requirements, and this application does not make specific restrictions. After the cleaning is completed, the first nozzle is closed.

[0022] S3: Spraying a cleaning liquid onto the wafer through the second nozzle to rinse the surface of the wafer, wherein the cleaning liquid is deionized water with a resistivity of no more than 0.7 Mohm·cm.

[0023] Exemplarily, a cleaning liquid is sprayed onto the wafer through the second nozzle, so that the front and back sides of the wafer are rinsed with the cleaning liquid. The cleaning liquid is deionized water with a resistivity of no more than 0.7 Mohm·cm, and the cleaning liquid has a high positive charge concentration, so that the electronegativity of the residual silicon chips can be effectively neutralized, and the adsorption capacity of the silicon chips on the positively charged silicon nitride surface can be weakened. After the cleaning is completed, the second nozzle is closed.

[0024] Furthermore, in this step, the wafer is rinsed with the cleaning solution for at least 30 seconds to ensure a cleaning effect.

[0025] S4: Use the third nozzle to spray the second fluid toward the wafer to flush the wafer surface.

[0026] Exemplarily, the third nozzle is used to spray two fluids onto the surface of the wafer, so that the two fluids are used to flush the front and back sides of the wafer to further remove silicon chips remaining on the surface of the wafer.

[0027] Furthermore, in this step, the second fluid is deionized water carrying nitrogen.

[0028] Furthermore, in this step, the rotation speed of the third nozzle can be reduced so that each part of the wafer surface is fully cleaned and the cleaning ability is improved. For example, the angular speed of the third nozzle can be set to 0.3° / s.

[0029] S5: Transfer the cleaned wafer to a wafer transfer box.

[0030] After cleaning, the wafer is transferred to a wafer transfer box and proceeds to subsequent processes.

[0031] Furthermore, before the above step S1, the following steps may also be included: S01: By adjusting the concentration of carbon dioxide, the resistivity of the cleaning liquid is adjusted to no more than 0.7 Mohm·cm.

[0032] For example, before cleaning, the resistivity of the cleaning liquid needs to be adjusted. Therefore, the resistivity of the cleaning liquid can be adjusted to no more than 0.7 Mohm·cm by adjusting the concentration of carbon dioxide therein.

[0033] S02: Use the second nozzle to spray the cleaning fluid for a predetermined period of time to ensure that the resistivity of the cleaning fluid in the pipeline connected to the second nozzle is stable.

[0034] Exemplarily, the second nozzle is used to spray the cleaning fluid for a predetermined period of time, thereby removing old cleaning fluid in the pipe connected to the second nozzle, ensuring that the resistivity of the cleaning fluid sprayed subsequently is no greater than 0.7 Mohm·cm.

[0035] The present application provides a method for removing silicon chips from the surface of a wafer. By setting the cleaning liquid to deionized water with a resistivity of no more than 0.7 Mohm·cm, when the cleaning liquid is used to clean a wafer with silicon chips remaining on the surface, the electronegativity of the remaining silicon chips can be effectively neutralized, and the adsorption capacity of the silicon chips on the positively charged silicon nitride surface can be weakened, thereby improving the cleaning effect of the silicon chips and effectively removing the silicon chips remaining on the surface of the wafer. Figure 2-1 and 2-2 , respectively show the defect distribution diagrams of the wafer before and after using this method. It can be found that after using this method, the defects are significantly reduced.

[0036] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection created by this application.

Claims

1. A method for removing silicon chips residue on the surface of a wafer, characterized in that: include: S1: Provide wafers after edge cutting process; S2: spraying ozone water toward the wafer through a first nozzle to rinse the surface of the wafer; S3: spraying a cleaning liquid toward the wafer through a second nozzle to rinse the surface of the wafer, wherein the cleaning liquid is deionized water having a resistivity of no more than 0.7 Mohm·cm; S4: using a third nozzle to spray two fluids toward the wafer to flush the surface of the wafer; S5: Transferring the cleaned wafer to a wafer transfer box.

2. The method for removing silicon chips residue on the surface of a wafer according to claim 1, characterized in that: Before the S1, it also includes: By adjusting the concentration of carbon dioxide, the resistivity of the cleaning liquid is adjusted to no more than 0.7 Mohm·cm; The cleaning fluid is sprayed using the second nozzle for a predetermined period of time to ensure that the resistivity of the cleaning fluid in the pipeline connected to the second nozzle is stable.

3. The method for removing silicon chips residue on the surface of a wafer according to claim 2, characterized in that: The predetermined duration is not less than 15 minutes.

4. The method for removing silicon chips residue on the surface of a wafer according to claim 1, characterized in that: In S4, the angular velocity of the rotation of the third nozzle is 0.3° / s.

5. The method for removing silicon chips residue on the surface of a wafer according to claim 1, characterized in that: The second fluid is deionized water carrying nitrogen.

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