Wafer cleaning method
Through the carbon dioxide cleaning step of splitting the wafer, the back of the wafer is first rinsed with SC1 standard cleaning solution, then the front of the wafer is rinsed with SC1 standard cleaning solution, and the back of the wafer is rinsed with SC1 standard cleaning solution, which solves the problem of volcanic defects caused by the accumulation of charge on the substrate surface, and achieves the effect of reducing the probability of volcanic defects and shortening the cleaning time.
Patent Information
- Application Number
- CN202311458772.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-03
- Publication Date
- 2025-05-06
AI Technical Summary
In semiconductor manufacturing process, the accumulation of charge on the substrate surface leads to the occurrence of volcanic defects, affecting the deposition quality of the material layer.
By splitting the original carbon dioxide cleaning steps on the front and back of the wafer, first SC1 standard cleaning solution is rinsed on the back of the wafer, then rinsed on the front of the wafer, and then rinsed on the back of the wafer, SC1 standard cleaning solution is rinsed on the back to derive most charges and reduce the probability of volcanic defects.
This method can greatly reduce the occurrence of volcanic defects, from about 0.27% to 0.15%, while shortening the cleaning time, from 45 seconds to less than 30 seconds, improving the yield and efficiency of the semiconductor manufacturing process.
Smart Images
Figure CN119943645A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor manufacturing technology, and in particular to a cleaning method for reducing volcano defects caused by charge accumulation on the surface of a substrate. Background Art
[0002] In the semiconductor manufacturing process, the cleaning step is a very common step, which is used to remove residual liquid or impurities on the surface of the material layer after etching or grinding. However, in the process of material layer accumulation, volcano defects may be formed due to excessive charge accumulated on the substrate surface. The so-called volcano defect means that when too much charge accumulates on the substrate surface, when the subsequent accumulation material liquid contacts the substrate surface, the charge will be released instantly and produce a local explosion effect (similar to an electrostatic reaction). This volcano defect will cause defects in the deposition of the material layer.
[0003] Therefore, it is necessary to study a method to reduce or solve the occurrence probability of the above-mentioned volcanic defects on the substrate surface. Summary of the invention
[0004] The present invention provides a method for cleaning a wafer, comprising providing a wafer, performing a first cleaning step on the wafer, wherein the first cleaning step comprises rinsing a back side of the wafer with an SC1 standard cleaning solution, and performing a second cleaning step on the wafer, wherein the second cleaning step comprises rinsing a front side of the wafer with a carbon dioxide water solution and rinsing the back side of the wafer with another SC1 standard cleaning solution.
[0005] According to the method provided by the present invention, the original step of simultaneously cleaning the front and back sides of the wafer with carbon dioxide water is split into two cleaning steps, that is, the back side of the wafer is first rinsed with SC1 standard cleaning solution, and then the front side of the wafer is rinsed with carbon dioxide water, and the back side is rinsed with SC1 standard cleaning solution. In this way, most of the charges accumulated on the wafer can be firstly discharged from the back side of the wafer, avoiding the accumulation of charges on the front side of the wafer, which can greatly reduce the probability of volcano defects. BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Figure 1 A schematic diagram of wafer cleaning and a schematic diagram of charge flow in a cross-sectional structure of a wafer according to an embodiment of the present invention;
[0007] Figure 2 and Figure 3 FIG. 1 is a schematic diagram of wafer cleaning and a schematic diagram of charge flow in a cross-sectional structure of a wafer according to another embodiment of the present invention.
[0008] Main component symbols
[0009] 10: Carbon dioxide water
[0010] 12: Electronic components
[0011] 20:SC1 standard cleaning fluid
[0012] A:front
[0013] B: Back
[0014] Q: Charge
[0015] W: Wafer DETAILED DESCRIPTION
[0016] In order to enable a person skilled in the art to further understand the present invention, the preferred embodiments of the present invention are listed below, and the components and intended effects of the present invention are described in detail with reference to the accompanying drawings.
[0017] For the convenience of explanation, the drawings of the present invention are only for illustration to make it easier to understand the present invention, and the detailed proportions can be adjusted according to the design requirements. The upper and lower relationships of the relative elements in the drawings described in the text should be understood by those skilled in the art to refer to the relative positions of the objects, so they can be flipped to present the same components, which should all fall within the scope of the disclosure of this specification, and will be explained here first.
[0018] Figure 1 A schematic diagram of wafer cleaning and a schematic diagram of charge flow in a cross-sectional structure of a wafer according to an embodiment of the present invention are shown, wherein the upper half shows a schematic diagram of wafer cleaning and the lower half shows a schematic diagram of charge flow in a cross-sectional structure of a wafer. Figure 1 As shown, a wafer W is provided, and the wafer W includes a front side A and a back side B. At this time, the front side A of the wafer W may have formed some electronic components 12 (such as transistors, etc., but not limited to this). Then, a cleaning step is performed on the wafer W. The purpose of the cleaning step is to remove impurities or etching liquids remaining on the surface of the wafer, and the cleaning step can also help to derive some charges on the surface of the wafer W. In other words, the cleaning step described in the present invention is performed before some components have been formed on the surface of the wafer W and the cleaning step is about to be performed.
[0019] exist Figure 1 In the embodiment shown, Figure 1As shown in the upper half of the figure, the wafer W is placed on a turntable (not shown) and rotated at a speed of about 30 to 200 rpm, but not limited thereto. While rotating, the front side A and the back side B of the wafer W are simultaneously rinsed with carbon dioxide water 10, and the carbon dioxide water 10 is sprayed through a nozzle (not shown) to the center of the front side A and the back side B of the wafer W or its vicinity, and the spraying rate is about 2 liters / minute. Then, by rotating the wafer W, the carbon dioxide water 10 is diffused from the center to the outside to achieve the cleaning purpose.
[0020] The carbon dioxide water 10 is used for cleaning for two purposes: one is to remove impurities and residual liquid on the front and back sides of the wafer W, and the other is to remove the accumulated charge on the surface of the wafer W. Figure 1 As shown in the lower half of , the charge Q is extracted from the front side A and the back side B of the wafer W, as shown by the direction of the arrows.
[0021] However, the applicant found that Figure 1 Although the implementation method can extract the charge, it takes a long time. In the current semiconductor manufacturing process, it takes about 45 seconds to clean the carbon dioxide water, which is not conducive to the speed of the semiconductor manufacturing process.
[0022] Therefore, the applicant provides another step of cleaning the wafer. Figure 2 and Figure 3 A schematic diagram of wafer cleaning and a schematic diagram of charge flow in a cross-sectional structure of a wafer according to another embodiment of the present invention are shown, wherein the upper half shows a schematic diagram of wafer cleaning and the lower half shows a schematic diagram of charge flow in a cross-sectional structure of a wafer. Figure 2 and Figure 3 As shown, the original ( Figure 1 The carbon dioxide water washing step in the embodiment shown in the figure is divided into two stages, namely, Figure 2 During the rotation of the wafer W, only the back side B of the wafer W is cleaned with the SC1 standard cleaning solution 20, and then Figure 3 As shown, the back side B of the wafer W is continuously cleaned with the SC1 standard cleaning solution 20 during the rotation of the wafer W, and the front side A of the wafer W is cleaned with the carbon dioxide water 10. In this embodiment, the rotation speed of the wafer W is about 30-200 rpm, the ejection rate of the SC1 standard cleaning solution 20 is about 0.5-2 liters / minute, the ejection rate of the carbon dioxide water 10 is about 2 liters / minute, and the other two cleaning steps ( Figure 2 and Figure 3 The total time of the steps shown in the figure is about 5-30 seconds, wherein the first cleaning step ( Figure 2 The cleaning step shown) and the second cleaning step ( Figure 3 The time ratio of the cleaning step shown is about 1:1, but is not limited to this.
[0023] In this embodiment, the SC1 standard cleaning solution 20 is a mixed solution of ammonia water, hydrogen peroxide and water. The remaining features belong to the prior art in this field and will not be elaborated here.
[0024] like Figure 2 and Figure 3 As shown in the lower half of the figure, since the conductivity of the SC1 standard cleaning solution 20 is much higher than that of carbon dioxide water (about 100 times), and most of the electronic components 12 are formed on the front side of the wafer W, when the back side of the wafer is cleaned with the SC1 standard cleaning solution 20 first, most of the charges Q will be derived from the back side B of the wafer W. Since the conductivity of the SC1 standard cleaning solution 20 is higher, the amount of charges Q derived at this time will be greater than Figure 1 The amount of charge Q shown is that extracted from the back side of the wafer W. Since the flow path of the charge Q does not pass through the front side A of the wafer W, the electronic components 12 on the front side A of the wafer W will not be damaged.
[0025] Follow up Figure 3 As shown, the front side A of the wafer W is rinsed with carbon dioxide water 10, and the back side B of the wafer W is rinsed with SC1 standard cleaning solution 20. In this way, impurities and residues on the front side A of the wafer W can be cleaned, and the hydrophilicity of the surface of the wafer W can be improved at the same time. It is also worth noting that although there will be charges Q being derived from the front side of the wafer W, since the conductivity of the carbon dioxide water 10 is lower than that of the SC1 standard cleaning solution 20, the amount of charges Q flowing out from the front side A is small, and it is not easy to damage the electronic components 12 on the front side A.
[0026] According to the experimental results of the applicant, the second embodiment of the present invention ( Figures 2 to 3 The embodiment shown in the figure can reduce the probability of volcano defects by about half, from about 0.27% to 0.15% according to statistical results, and the cleaning time can also be shortened from 45 seconds to less than 30 seconds, thus helping to improve the yield and efficiency of the semiconductor manufacturing process.
[0027] After the cleaning step is completed, the wafer W may be subjected to other cleaning steps, such as cleaning specific impurities with a chemical solution (such as hydrofluoric acid, sulfuric acid or ammonia water), or rinsing with deionized water. These cleaning steps belong to the prior art in the field and will not be repeated.
[0028] In summary, the present invention provides a method for cleaning a wafer, comprising providing a wafer W, performing a first cleaning step ( Figure 2 The first cleaning step includes rinsing a back side B of the wafer W with a SC1 standard cleaning solution 20, and performing a second cleaning step ( Figure 3The second cleaning step includes washing a front side A of the wafer W with a carbon dioxide water 10, and washing a back side B of the wafer W with another SC1 standard cleaning solution 20.
[0029] In some embodiments of the present invention, the solution used in the rinsing of the SC1 standard cleaning solution 20 includes a mixed solution of ammonia water, hydrogen peroxide and water.
[0030] In some embodiments of the present invention, the total time of performing the first cleaning step and the second cleaning step is between 5 and 30 seconds.
[0031] In some embodiments of the present invention, during the first cleaning step, a backside nozzle (not shown) sprays the SC1 standard cleaning solution 20 onto the backside B of the wafer W, and the wafer W continues to rotate.
[0032] In some embodiments of the present invention, when the second cleaning step is performed, the SC1 standard cleaning solution 20 is sprayed onto the back side B of the wafer W by a back nozzle, and the carbon dioxide water 10 is sprayed onto the front side A of the wafer W by a front nozzle (not shown), and the wafer W continues to perform a rotation step.
[0033] In some embodiments of the present invention, during the first cleaning step or the second cleaning step, the rotation speed of the wafer is between 30 and 300 rpm.
[0034] In some embodiments of the present invention, during the first cleaning step, the back side nozzle sprays the SC1 standard cleaning solution 20 at a flow rate of 0.5 to 2 liters / minute.
[0035] In some embodiments of the present invention, during the first cleaning step, the back nozzle sprays the SC1 standard cleaning solution 20 at a flow rate of 0.5 to 2 liters / minute, and the front nozzle sprays the carbon dioxide water 10 at a flow rate of 2 liters / minute.
[0036] In some embodiments of the present invention, when the first cleaning step is performed, the charges Q accumulated on the wafer W are conducted away through the back side B of the wafer W by the SC1 standard cleaning solution 20 .
[0037] In some embodiments of the present invention, when the second cleaning step is performed, the charge Q accumulated on the wafer W is discharged through the back side B of the wafer W by the SC1 standard cleaning solution 20 and through the front side A of the wafer W by the carbon dioxide water 10.
[0038] In some embodiments of the present invention, after the second cleaning step, the surface of the wafer W is further chemically cleaned.
[0039] In some embodiments of the present invention, the chemical cleaning solution includes hydrofluoric acid, sulfuric acid or ammonia water.
[0040] In some embodiments of the present invention, after the chemical cleaning, the wafer is further cleaned with deionized water to remove residual liquid left in the chemical cleaning process.
[0041] In some embodiments of the present invention, the front side A of the wafer W includes a material layer or an electronic component 12 .
[0042] In some embodiments of the present invention, the second cleaning step is performed after the first cleaning step is performed.
[0043] In some embodiments of the present invention, after the wafer W is subjected to the second cleaning step, the amount of charges contained in the front side A of the wafer W is less than 2 coulombs / cm2.
[0044] According to the method provided by the present invention, the original step of simultaneously cleaning the front and back sides of the wafer with carbon dioxide water is split into two cleaning steps, that is, the back side of the wafer is first rinsed with SC1 standard cleaning solution, and then the front side of the wafer is rinsed with carbon dioxide water, and the back side is rinsed with SC1 standard cleaning solution. In this way, most of the charges accumulated on the wafer can be firstly discharged from the back side of the wafer, avoiding the accumulation of charges on the front side of the wafer, which can greatly reduce the probability of volcano defects.
[0045] The above descriptions are only preferred embodiments of the present invention. All equivalent changes and modifications made according to the claims of the present invention should fall within the scope of the present invention.
Claims
1. A method for cleaning a wafer, characterized in that : Provide wafers; Performing a first cleaning step on the wafer, the first cleaning step comprising rinsing the back side of the wafer with SC1 standard cleaning solution; and The wafer is subjected to a second cleaning step, wherein the second cleaning step comprises washing the front side of the wafer with carbon dioxide water and washing the back side of the wafer with another SC1 standard cleaning solution.
2. The method for cleaning a wafer according to claim 1, wherein the solution used in the SC1 standard cleaning solution rinse comprises a mixed solution of ammonia water, hydrogen peroxide and water. 3 . The method for cleaning a wafer according to claim 1 , wherein the total time for performing the first cleaning step and the second cleaning step is between 5 and 30 seconds.
4. The method for cleaning a wafer according to claim 1, wherein during the first cleaning step, the SC1 standard cleaning solution is sprayed onto the back side of the wafer through a back side nozzle, and the wafer continues to rotate.
5. The method for cleaning a wafer according to claim 4, wherein during the second cleaning step, the SC1 standard cleaning solution is sprayed onto the back side of the wafer by the back nozzle, and the carbon dioxide water is sprayed onto the front side of the wafer by the front nozzle, and the wafer continues to rotate. 6 . The method for cleaning a wafer according to claim 5 , wherein during the first cleaning step or the second cleaning step, the rotation speed of the wafer is between 30 and 300 rpm.
7. The method for cleaning a wafer according to claim 5, wherein during the first cleaning step, the back side nozzle sprays the SC1 standard cleaning solution at a flow rate of 0.5 to 2 liters per minute.
8. The method for cleaning a wafer according to claim 5, wherein during the first cleaning step, the back nozzle sprays the SC1 standard cleaning solution at a flow rate of 0.5 to 2 liters / minute, and the front nozzle sprays the carbon dioxide water at a flow rate of 2 liters / minute. 9 . The method for cleaning a wafer according to claim 1 , wherein when the first cleaning step is performed, the charges accumulated on the wafer are conducted away by the SC1 standard cleaning solution through the back side of the wafer.
10. The method for cleaning a wafer according to claim 1, wherein when performing the second cleaning step, the charges accumulated on the wafer are discharged through the back side of the wafer by the SC1 standard cleaning solution, and are discharged through the front side of the wafer by the carbon dioxide water. 11 . The method for cleaning a wafer according to claim 1 , further comprising chemically cleaning the surface of the wafer after the second cleaning step. 12 . The method for cleaning a wafer according to claim 11 , wherein the chemical cleaning solution comprises hydrofluoric acid, sulfuric acid or ammonia water. 13 . The method for cleaning a wafer according to claim 11 , further comprising cleaning the wafer with deionized water after the chemical cleaning to remove residual liquid left in the chemical cleaning process. 14 . The method for cleaning a wafer according to claim 1 , wherein the front side of the wafer comprises a material layer or an electronic component. 15 . The method for cleaning a wafer according to claim 1 , wherein the second cleaning step is performed after the first cleaning step is performed. 16 . The method for cleaning a wafer according to claim 1 , wherein after the second cleaning step is performed on the wafer, the amount of charge contained in the front surface of the wafer is less than 2 coulombs / cm 2 .