Wafer cleaning method

Abstract

This invention discloses a wafer cleaning method, which includes: placing a wafer in a housing; using a spraying assembly to spray fluid toward the wafer, the spraying direction matching the rotation direction of the wafer, and spraying fluid toward the wafer at different angles so that the sprayed fluid covers the wafer surface; and moving cleaning brushes located on both sides of the wafer to a cleaning position to perform roller brush cleaning on both sides of the wafer.

Description

Technical Field

[0001] This invention belongs to the field of wafer post-processing technology, and more specifically, relates to a wafer cleaning method. Background Technology

[0002] The integrated circuit industry is the core of the information technology industry, playing a crucial role in promoting the digital and intelligent transformation and upgrading of the manufacturing industry. Chips are the carriers of integrated circuits, and chip manufacturing involves processes such as integrated circuit design, wafer manufacturing, wafer processing, electrical measurement, dicing, packaging, and testing.

[0003] During wafer manufacturing, contaminants such as particles or organic matter adsorb onto the wafer surface, resulting in numerous defects that require post-processing to remove. In particular, the chemical reagents and abrasives used extensively in Chemical Mechanical Polishing (CMP) can contaminate the wafer surface. Therefore, post-processing is necessary after polishing to remove these contaminants. Post-processing typically consists of cleaning and drying to provide a smooth and clean wafer surface.

[0004] Wafer cleaning methods include roller brush cleaning and megasonic cleaning, among which roller brush cleaning is more widely used. For example, the wafer cleaning device disclosed in patent CN112233971B vertically supports the wafer and rotates it using support rollers. A spray structure on the housing supplies cleaning and rinsing solutions to the wafer. The spray structure adopts a symmetrical design, with five nozzles on each side of the spray nozzle. The landing points of the sprayed fluid on the wafer are symmetrical about the longitudinal section passing through the center of the wafer. Figure 1 As shown.

[0005] Figure 1 In this process, a solid cone nozzle is used, resulting in a stronger liquid flow in the center and a weaker flow at the edges. Therefore, the wafer surface near the center of the nozzle's spray point has a strong capacity for delivering cleaning and rinsing solutions, which can be designated as the strong action area. When the wafer is stationary, the strong action area is only distributed in a limited number of 5 locations. Wafer rotation can improve the uniformity of liquid distribution to some extent, but the rotating wafer will cause the liquid to spread away from the wafer center under the action of centrifugal force. This results in insufficient liquid being directly sprayed near the wafer center. Insufficient cleaning and rinsing solutions in the wafer center area can easily lead to cleaning defects in that area, especially in certain metal processing processes, which have higher requirements for the distribution of cleaning and rinsing solutions and need to improve the liquid supply capacity of cleaning and rinsing solutions in the wafer center. Summary of the Invention

[0006] This invention provides a wafer cleaning method, which aims to at least solve one of the technical problems existing in the prior art.

[0007] An embodiment of the present invention provides a wafer cleaning method, comprising:

[0008] S1, Place the wafer in the housing;

[0009] S2, using a liquid spraying assembly to spray fluid toward the wafer, the spraying direction matching the wafer's rotation direction, and spraying fluid toward the wafer at different angles so that the sprayed fluid covers the wafer surface;

[0010] S3, the cleaning brushes located on both sides of the wafer move to the cleaning position to perform roller cleaning on both sides of the wafer.

[0011] In some embodiments, the liquid spraying assembly includes nozzles disposed on the upper side of the wafer to spray fluid toward different regions of the wafer.

[0012] In some embodiments, the number of nozzles is multiple, for spraying fluid toward the wafer edge region, the center region and the middle region, and the sprayed fluids are arranged in an alternating manner.

[0013] In some embodiments, at least two nozzles are disposed toward the edge region of the wafer and are directed toward each other; the points where the fluid jets from the nozzles land are staggered.

[0014] In some embodiments, the nozzle disposed along the wafer rotation direction has a smaller orifice than the through nozzle.

[0015] In some embodiments, the nozzle disposed toward the center region of the wafer has its spray point located above the center point of the wafer.

[0016] In some embodiments, the nozzles facing different regions of the wafer are at different angles to the horizontal plane where the wafer post-processing apparatus is located.

[0017] In some embodiments, the angle between the nozzle disposed toward the middle region of the wafer and the horizontal plane where the wafer post-processing device is located is greater than the angle between the nozzle disposed toward the edge region of the wafer and the horizontal plane where the wafer post-processing device is located.

[0018] In some embodiments, the angle between the nozzle disposed toward the center region of the wafer and the horizontal plane where the wafer post-processing device is located is greater than the angle between the nozzle disposed toward the middle region of the wafer and the horizontal plane where the wafer post-processing device is located.

[0019] In some embodiments, the nozzle can adjust its spray direction, with nozzles positioned toward different regions of the wafer forming different angles with the vertical plane of the wafer post-processing apparatus.

[0020] The beneficial effects of this invention include:

[0021] a. The nozzles are configured to spray fluid from the top of the wafer at different angles, so that the fluid completely covers the wafer surface and forms a thick liquid film, prolonging the fluid's contact time on the wafer surface, achieving thorough cleaning, and reducing the number of wafer post-processing defects.

[0022] b. Nozzles facing the center of the wafer are selected with good fluid convergence performance to overcome the centrifugal force in the middle of the wafer and deliver fresh fluid towards the center of the wafer, thereby enhancing the cleaning ability of the center area of ​​the wafer. Attached Figure Description

[0023] The advantages of the present invention will become clearer and easier to understand through the following detailed description in conjunction with the accompanying drawings, which are merely illustrative and do not limit the scope of protection of the present invention, wherein:

[0024] Figure 1 This is a schematic diagram of the liquid spraying structure in a wafer cleaning device in the prior art;

[0025] Figure 2 This is a schematic diagram of a wafer post-processing apparatus provided in an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of a liquid spraying assembly provided in an embodiment of the present invention disposed on the upper side of a wafer;

[0027] Figure 4 This is a flowchart of a wafer cleaning method provided in an embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram showing the corresponding tilt angle of the nozzles on the liquid spraying assembly;

[0029] Figure 6 This is a schematic diagram of a nozzle with a fixing component provided in an embodiment of the present invention. Detailed Implementation

[0030] The technical solutions of the present invention will be described in detail below with reference to specific embodiments and accompanying drawings. The embodiments described herein are specific implementations of the present invention, used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary, and should not be construed as limiting the implementation methods or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can employ other obvious technical solutions based on the content disclosed in the claims and specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein.

[0031] The accompanying drawings in this specification are schematic diagrams used to illustrate the concept of the invention and to schematically show the shapes of the various parts and their interrelationships. It should be understood that, in order to clearly show the structure of the various components of the embodiments of the invention, the drawings are not drawn to the same scale, and the same reference numerals are used to indicate the same parts in the drawings.

[0032] In this invention, "Chemical Mechanical Polishing (CMP)" is also called "Chemical Mechanical Planarization (CMP)," and the wafer (W) is also called the substrate (Substrate), with the same meaning and actual function.

[0033] This invention provides a wafer post-processing apparatus, the schematic diagram of which is shown below. Figure 2 As shown. The wafer post-processing apparatus includes a housing 10, inside which a liquid spraying assembly 20 and a cleaning brush 30 are disposed.

[0034] Figure 2 In the process, the liquid spraying assembly 20 is disposed on the upper side of the wafer W. The liquid spraying assembly 20 includes multiple nozzles, the spraying direction of which matches the rotation direction of the wafer W. The nozzles spray towards the wafer surface at different angles so that the sprayed fluid fully covers the surface of the wafer W.

[0035] When the spraying assembly 20 sprays cleaning fluid, the cleaning fluid completely covers the wafer surface to improve the cleaning capability of the wafer; when the spraying assembly 20 sprays rinsing fluid, such as deionized water (DIW), the complete coverage of the rinsing fluid can improve the rinsing capability of the wafer.

[0036] Furthermore, the nozzles are positioned on the upper side of wafer W to spray fluid toward different areas of wafer W, such as... Figure 3 As shown. Specifically, multiple nozzles spray fluid toward the edge region, the center region, and the middle region of the wafer.

[0037] To avoid splashing caused by the fluids ejected from the nozzles colliding with each other, the nozzles need to be staggered. Figure 3 This is a front view of the wafer to be cleaned. The nozzle spray direction indicator line is projected onto the surface due to the spray direction. Figure 3 The fluids intersect in the three-dimensional space, while the actual fluids are staggered to avoid head-on collisions that could cause splashing.

[0038] Figure 3In the illustrated embodiment, a columnar nozzle is used instead of the solid cone nozzle in the prior art. The fluid sprayed by the columnar nozzle has good converging properties, so as to accurately supply the liquid and avoid the nozzle spraying the fluid outside the wafer edge, thereby improving the utilization rate of the wafer cleaning fluid.

[0039] As an embodiment of the present invention, the liquid spraying assembly 20 includes four nozzles, namely a first nozzle 20a, a second nozzle 20b, a third nozzle 20c, and a fourth nozzle 20d, as shown below. Figure 3 As shown, multiple nozzles are staggered on the upper side of wafer W, and the sprayed fluid is rapidly dispersed on the wafer surface under the action of gravity and centrifugal force.

[0040] In this invention, at least two nozzles are arranged toward the edge region of the wafer, and they fire at each other. Figure 3 In this process, the first nozzle 20a and the fourth nozzle 20d spray fluid alternately towards the edge region of the wafer. The spray direction of the first nozzle 20a is in the same direction as the wafer's rotation, while the spray direction of the fourth nozzle 20d is opposite to that of the first nozzle 20a. The staggered landing points of the fluid sprayed from the first nozzle 20a and the fourth nozzle 20d prevent head-on collisions that could cause splashing. This also facilitates the rapid spread of the liquid stream onto the wafer surface, achieving complete coverage of the wafer surface.

[0041] Meanwhile, this invention provides a wafer cleaning method, the flowchart of which is as follows: Figure 4 As shown, a wafer cleaning method includes:

[0042] S1, Place the wafer in the housing 10;

[0043] S2, the liquid spraying assembly 20 sprays fluid toward the wafer in a direction that matches the wafer's rotation direction, and sprays fluid toward the wafer at different angles so that the sprayed fluid covers the wafer surface;

[0044] S3, the cleaning brushes 30 located on both sides of the wafer move to the cleaning position to perform roller cleaning on both sides of the wafer.

[0045] Figure 3 In the illustrated embodiment, the orifice diameter of the fourth nozzle 20d is larger than that of the first nozzle 20a to ensure that more fluid is sprayed towards the edge region of the wafer. The fluid sprayed by the nozzle can cover a larger area as the wafer rotates, so as to form a uniform liquid film on the wafer surface and improve the cleaning ability of the wafer surface.

[0046] Preferably, the orifice diameter of the fourth nozzle 20d is 1.5 to 3 mm, while the orifice diameter of the first nozzle 20a is 1 to 2 mm, so as to supply sufficient fluid at the edge of the wafer, thereby forming a thicker liquid film on the wafer surface.

[0047] To address the problem of insufficient liquid supply in the wafer center region, which frequently leads to defects, the third nozzle 20c sprays towards the wafer center region to directly supply cleaning or rinsing solution to the wafer center. Specifically, the nozzle positioned towards the wafer center region has its spray point located above the wafer center point.

[0048] With this configuration, the fluid ejected from the third nozzle 20c can quickly cover the central area of ​​the wafer under the action of gravity and inertia, ensuring the supply capacity of cleaning or rinsing fluid, thereby reducing cleaning defects caused by insufficient fluid supply in the central area and improving the cleaning effect of the wafer.

[0049] Figure 3 The liquid spraying assembly also includes a second nozzle 20b, which sprays fluid toward the central region of the wafer. Here, the central region is relative to the edge region and the center region; that is, the central region is located between the edge region and the center region. The spray point of the second nozzle 20b is located below the first nozzle 20a and the fourth nozzle 20d and above the third nozzle 20c.

[0050] During wafer cleaning, multiple nozzles simultaneously spray fluid toward the wafer. Figure 3 The dividing lines in the middle section are merely an exaggerated illustration to better demonstrate the technical solution. In reality, the liquid film on the wafer surface is continuous, without discontinuities or clear boundaries. The fluids ejected from different nozzles naturally merge on the wafer surface to form a continuous liquid film.

[0051] In another embodiment of the present invention, the nozzles facing the middle region of the wafer have different angles with the horizontal plane where the wafer post-processing apparatus is located. Specifically, the angles between the first nozzle 20a, the second nozzle 20b, the third nozzle 20c, and the fourth nozzle 20d and the horizontal plane where the wafer post-processing apparatus is located are α1, α2, α3, and α4, respectively. Figure 5 As shown, the longitudinal section passing through the center of the wafer is represented by a dashed line.

[0052] Furthermore, the angle α2 between the second nozzle 20b, which is positioned towards the center region of the wafer, and the horizontal plane where the wafer post-processing device is located, is greater than the angle α1 between the first nozzle 20a, which is positioned towards the edge region of the wafer, and the horizontal plane where the wafer post-processing device is located. The angle α3 between the third nozzle 20c, which is positioned towards the center region of the wafer, and the horizontal plane where the wafer post-processing device is located, is greater than the angle α2 between the second nozzle 20b, which is positioned towards the center region of the wafer, and the horizontal plane where the wafer post-processing device is located.

[0053] Specifically, the angles α1 and α4 formed between the first nozzle 20a and the fourth nozzle 20d and the horizontal plane where the wafer post-processing device is located are approximately the same, and the angles α1 and α4 should be less than or equal to 30°. The angle α2 should be less than 45°, and the angle α3 should be greater than 40° and less than 80°.

[0054] Understandably, the angle between the nozzle and the horizontal plane of the vertical brushing device is adjustable to accommodate wafer cleaning of different sizes and process conditions. Specifically, the mounting base for fixing the nozzle can swing or rotate around a fixed point to adjust the nozzle spray angle.

[0055] In another embodiment of the present invention, the nozzles arranged toward different areas of the wafer have different angles with the vertical plane of the wafer post-processing device, that is, the nozzles arranged toward different areas of the wafer have different angles with the side of the wafer to be cleaned.

[0056] Figure 6 This is a schematic diagram of a nozzle 20a disposed on a fixing assembly 40 according to an embodiment of the present invention. The fixing assembly 40 includes a support member 41 and a mounting member 42, the support member 41 being disposed on... Figure 2 The housing 10 shown has a mounting member 42 rotatably connected to a support member 41, and a nozzle 20a is disposed on the side of the mounting member 42.

[0057] Furthermore, the mounting component 42 has an L-shaped structure, and the nozzle 20a is rotatably connected to the mounting component 42 to adjust the position and orientation of the nozzle 20a according to the disclosure, so as to meet the process requirements of wafer post-processing.

[0058] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0059] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A wafer cleaning method, characterized in that, include: S1, Place the wafer in the housing along the vertical plane of the wafer post-processing device; S2, using a liquid spraying assembly to spray fluid toward the wafer, the spraying direction matching the wafer's rotation direction, and spraying fluid toward the wafer at different angles so that the sprayed fluid covers the wafer surface; S3, the cleaning brushes located on both sides of the wafer move to the cleaning position to perform roller cleaning on both sides of the wafer; The liquid spraying assembly includes four nozzles: a first nozzle, a second nozzle, a third nozzle, and a fourth nozzle, which are arranged sequentially in the horizontal direction and located on the upper side of the wafer to spray fluid toward different areas of the wafer. The first and fourth nozzles spray fluid toward the upper edge region of the wafer, the third nozzle sprays fluid toward the center region of the wafer, and the second nozzle sprays fluid toward the middle region of the wafer, the middle region being located between the edge region and the center region. The spray point of the second nozzle is located below the first and fourth nozzles and above the third nozzle. The first and fourth nozzles spray fluid toward each other, and the spray points of the fluids they spray are staggered. The spraying direction of the first and second nozzles is consistent with the rotation direction of the wafer. The fluids ejected from the four nozzles naturally merge on the wafer surface to form a continuous liquid film.

2. The wafer cleaning method of claim 1, wherein, The first nozzle has a smaller orifice than the fourth nozzle.

3. The wafer cleaning method of claim 1, wherein The third nozzle's spray point is located above the center point of the wafer.

4. The wafer cleaning method of claim 1, wherein The nozzles, which are positioned towards different areas of the wafer, form different angles with the horizontal plane where the wafer post-processing unit is located.

5. The wafer cleaning method of claim 4, wherein The angle between the second nozzle and the horizontal plane where the wafer post-processing device is located is greater than the angle between the first nozzle and the fourth nozzle and the horizontal plane where the wafer post-processing device is located.

6. The wafer cleaning method of claim 4, wherein The angle between the third nozzle and the horizontal plane where the wafer post-processing device is located is greater than the angle between the second nozzle and the horizontal plane where the wafer post-processing device is located.

7. The wafer cleaning method as described in claim 1, characterized in that, The nozzle can adjust its spray direction, and the nozzles set toward different areas of the wafer have different angles with the vertical plane of the wafer post-processing device.

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