Cleaning Device and Cleaning Method

Abstract

The present invention provides a cleaning device and a cleaning method, including a carrier table for carrying and fixing a wafer to be cleaned; a rotating bearing located under the carrier table for driving the carrier table to rotate; a cleaning pipeline located in the middle of the rotating bearing, and through holes are provided on the side wall of the cleaning pipeline; a gas pipeline connected to the through holes for purging a protective gas into the gap between the cleaning pipeline and the rotating bearing, so as to prevent foreign matters from being brought into the back surface of the wafer adsorbed through the gap by the airflow generated by the high-speed rotation of the rotating bearing. The present invention provides through holes on the side wall of the cleaning pipeline, and purges the protective gas into the gap between the rotating bearing and the cleaning pipeline through the through holes, preventing foreign matters from the outside or metal particles on the surface of the rotating bearing from being brought into and adsorbed on the back surface of the wafer through the gap by the airflow generated by the high-speed rotation of the rotating bearing, thereby improving the particle and metal contamination on the wafer surface and avoiding the adverse effects of the bulk metal contamination on the wafer surface on the products of the subsequent process.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and particularly to a cleaning device and a cleaning method. Background Art

[0002] In the process of semiconductor integrated circuit manufacturing, in order to avoid damage to the circuits and devices manufactured in the wafer caused by contaminants such as particles, organic substances, and metal contaminants, the wafer needs to be cleaned after each process. The surface of the semiconductor wafer must always be kept clean. Not only the front side of the wafer is required to be always clean, but also the back side of the wafer is required to be always clean to avoid cross-contamination during wafer transfer. Therefore, it is necessary to clean the front and back sides of the wafer. The wafer cleaning methods include batch cleaning and single-wafer cleaning. During batch cleaning, multiple wafers can be immersed in a cleaning tank for cleaning to remove contaminants on both the front and back sides of the wafers simultaneously. During single-wafer cleaning, the wafer is fixed on a single-wafer cleaning station, and one side of the wafer that does not need to be cleaned is protected, and a cleaning agent is sprayed by a nozzle to clean the side of the wafer that needs to be cleaned.

[0003] Figure 1 FIG. is a partial structural schematic diagram of a single-wafer cleaning station. As Figure 1 shown, a wafer chuck 11 holds a wafer 10 and rotates under the drive of a spindle 12. A backside nozzle 13 located in the middle of the spindle 12 supplies a cleaning reagent and a cleaning gas to the back side of the wafer 10 to clean the back side of the wafer 10. Since there is a gap L (about 2 mm) between the spindle 12 and the backside nozzle 13, the high-speed rotation of the spindle 12 will bring air outside the cavity into the back side of the wafer through the gap L, and metal particles (such as metallic iron) on the surface of the spindle 12 will be brought into the back side of the wafer 10 by the siphon phenomenon caused by the high-speed rotation of the spindle 12, causing contamination to the back side of the wafer 10. The metallic iron contamination on the wafer surface will diffuse into the silicon crystal in the high-temperature environment of epitaxial growth, thus having an adverse impact on the subsequent processes. Summary of the Invention

[0004] The purpose of the present invention is to provide a cleaning device and a cleaning method to improve the particle and metal contamination on the wafer surface and avoid the adverse impact of the bulk metal contamination on the wafer surface on the products of subsequent processes.

[0005] The present invention provides a cleaning device, including:

[0006] A carrier stage for carrying and fixing the wafer to be cleaned;

[0007] A spindle located under the carrier stage for driving the carrier stage to rotate;

[0008] A cleaning pipeline is located in the middle of the rotating bearing, and through holes are arranged on the side wall of the cleaning pipeline;

[0009] A gas pipeline is connected to the through hole of the cleaning pipeline and is used to purge a protective gas into the gap between the cleaning pipeline and the rotating bearing, so as to prevent foreign matters from being brought into the back surface of the wafer adsorbed through the gap by the airflow generated by the high-speed rotation of the rotating bearing.

[0010] Optionally, the through holes are distributed at multiple layers and spaced apart in the middle and lower parts of the cleaning pipeline.

[0011] Optionally, the through holes penetrate the side wall of the cleaning pipeline obliquely.

[0012] Optionally, the through holes are inclined downward, and the downward inclination angle of the through holes is 15 degrees to 60 degrees.

[0013] Optionally, multiple layers of the through holes are arranged in a spiral around the cleaning pipeline.

[0014] Optionally, each layer of the through holes is arranged circumferentially around the cleaning pipeline.

[0015] Optionally, the downward inclination angles of the through holes in the same layer are the same.

[0016] Optionally, the downward inclination angles of the through holes increase successively from bottom to top.

[0017] Optionally, the flow rate of the protective gas is 10 L / min to 20 L / min.

[0018] Correspondingly, the present invention also provides a cleaning method, including cleaning a wafer by using the cleaning device described in any one of the above.

[0019] In summary, the present invention provides a cleaning device and a cleaning method, including a carrier for carrying and fixing a wafer to be cleaned; a rotating bearing located under the carrier for driving the carrier to rotate; a cleaning pipeline located in the middle of the rotating bearing, and through holes are arranged on the side wall of the cleaning pipeline; a gas pipeline connected to the through holes and used to purge a protective gas into the gap between the cleaning pipeline and the rotating bearing, so as to prevent foreign matters from being brought into the back surface of the wafer adsorbed through the gap by the airflow generated by the high-speed rotation of the rotating bearing. The present invention arranges through holes on the side wall of the cleaning pipeline, and purges gas into the gap between the rotating bearing and the cleaning pipeline through the through holes, so as to prevent foreign matters from the outside or metal particles on the surface of the rotating bearing from being brought into and adsorbed on the back surface of the wafer through the gap by the airflow generated by the high-speed rotation of the rotating bearing, thereby improving the particle and metal contamination on the surface of the wafer and avoiding the adverse effects of the metal contamination on the surface of the wafer on the products in the subsequent process. Description of the Drawings

[0020] Figure 1 It is a partial structural schematic diagram of a single wafer cleaning machine;

[0021] Figure 2 It is a partial structural schematic diagram of a single wafer cleaning machine with a magnetic fluid filled in the gap between the rotating bearing and the back cleaning pipeline;

[0022] Figure 3 It is a structural schematic diagram of a cleaning device provided by an embodiment of the present invention;

[0023] Figure 4 It is a structural schematic diagram of a cleaning device provided by another embodiment of the present invention;

[0024] Figure 5 It is a cross-sectional structural schematic diagram of a cleaning pipeline of a cleaning device provided by an embodiment of the present invention;

[0025] Figure 6 It is a flowchart of a method for inspecting the cleaning effect on the back side of a wafer;

[0026] Figure 7 It is a comparison chart of the particle conditions on the back side of a wafer after cleaning by an existing single wafer cleaning device and a cleaning device provided by an embodiment of the present invention;

[0027] Figure 8 It is a data comparison chart of the bulk metal content on the surface of a wafer obtained by SPV testing of an epitaxial wafer grown after cleaning a wafer by an existing single wafer cleaning device and a cleaning device provided by an embodiment of the present invention.

[0028] Among them, the reference numerals are:

[0029] 10 - wafer; 11 - wafer chuck; 12 - rotating bearing; 13 - back cleaning pipeline; 14 - magnetic fluid; 100 - wafer; 110 - carrier stage; 120 - rotating bearing; 130 - cleaning pipeline; 131 - through hole. Detailed implementation manners

[0030] The following further elaborates on the cleaning device and cleaning method of the present invention in detail in conjunction with the accompanying drawings and specific embodiments. According to the following description and drawings, the advantages and features of the present invention will be clearer. However, it should be noted that the concept of the technical solution of the present invention can be implemented in various different forms and is not limited to the specific embodiments described herein. The accompanying drawings are all in very simplified forms and use non-precise scales, only for the purpose of conveniently and clearly assisting in explaining the purpose of the embodiments of the present invention.

[0031] In the specification, terms such as "first" and "second" are used to distinguish between similar elements and are not necessarily used to describe a specific order or chronological sequence. It is to be understood that, where appropriate, these terms so used may be interchanged, for example, such that the embodiments of the present invention described herein can be operated in an order different from that described or shown herein. Similarly, if the methods described herein include a series of steps, and the order of these steps presented herein is not necessarily the only order in which these steps can be executed, and some of the described steps may be omitted and / or some other steps not described herein may be added to the method. If a component in one drawing is the same as a component in other drawings, although these components can be easily recognized in all drawings, for the sake of clarity in the description of the drawings, this specification will not label the reference numerals of all identical components in each drawing.

[0032] During the IC manufacturing process, heavy metal contamination is the main cause of damage to the integrity of the PN junction and the gate oxide integrity (GOI). Researchers found that at the edge of the LOCOS oxide layer, a large number of dislocations are generated due to oxidation-induced stress concentration. Iron atoms in silicon are deposited along the dislocations, resulting in collector-emitter short-circuit failure. At room temperature, iron atoms in the interstitial position in silicon can migrate and combine with boron in the <111> direction to form an iron-boron complex that has electrical activity and can introduce deep energy levels, acting as a donor. Therefore, preventing metal contamination on the wafer surface is crucial. Wafer cleaning is a key step in removing metal particles on the wafer surface. However, during the single-wafer cleaning process, metal particles (such as metallic iron) on the surface of the rotating bearing 12 are rotated at high speed by the rotating bearing 12, and a siphon phenomenon will bring them into the back surface of the wafer 10, causing contamination to the back surface of the wafer 10. In the traditional process, the way to avoid metal contamination on the back surface of the wafer is to fill a magnetic fluid 14 in the gap between the rotating bearing 12 and the back cleaning pipeline 13, as Figure 2 shown. However, the method of filling with magnetic fluid has high requirements for hardware design, high cost, and needs to be replaced regularly.

[0033] In view of this, the present invention provides a cleaning device and a cleaning method. A through hole is provided on the side wall of the cleaning pipeline, and gas is blown through the through hole into the gap between the rotating bearing and the cleaning pipeline, so as to avoid foreign objects from the outside or metal particles on the surface of the rotating bearing being brought into and adsorbed on the back surface of the wafer by the airflow generated by the high-speed rotation of the rotating bearing, thereby improving the particle and metal contamination on the wafer surface and avoiding the adverse effects of metal contamination on the wafer surface on the products of the subsequent process.

[0034] Figure 3 is a schematic structural diagram of the cleaning device provided in this embodiment. As Figure 3As shown in the figure, a cleaning device provided in this embodiment includes: a carrier 110 for carrying and fixing a wafer 100 to be cleaned; a rotating bearing 120 located below the carrier 110 for driving the carrier 110 to rotate; a cleaning pipeline 130 located in the middle of the rotating bearing 120, and through holes 131 are provided on the side wall of the cleaning pipeline 130; a gas pipeline is connected to the through holes 131 of the cleaning pipeline for purging a protective gas into the gap L between the cleaning pipeline 130 and the rotating bearing 120, so as to prevent foreign matters from being brought into the back surface of the wafer 100 adsorbed through the gap L by the airflow generated by the high-speed rotation of the rotating bearing 120.

[0035] Specifically, as Figure 3 shown, the carrier 110 is, for example, a wafer chuck (Chunk), which carries and fixes the wafer 100 to be cleaned, is connected to the rotating bearing 120 below, and a cleaning conduit leading to the back surface of the wafer 100 is provided in the cleaning pipeline 130 located in the middle of the rotating bearing 120 for supplying a cleaning reagent to the back surface of the wafer. The carrier 110 drives the wafer 100 to rotate at a certain speed during the cleaning process under the rotation of the rotating bearing 120, improving the cleaning quality and efficiency. The through holes 131 are distributed at multiple layers and spaced apart in the middle and lower parts of the cleaning pipeline 130 for purging a protective gas (bearing N2) into the gap L between the cleaning pipeline 130 and the rotating bearing 120. Each layer of the through holes 131 is arranged circumferentially around the cleaning pipeline 130, or multiple layers of the through holes 131 are arranged spirally around the cleaning pipeline 130. Exemplarily, the through holes 131 are distributed at three layers and spaced apart in the middle and lower parts of the cleaning pipeline 130. The two layers of through holes 131 close to the wafer 100 are arranged spirally around the cleaning pipeline 130, and the layer of through holes 131 close to the bottom of the cleaning pipeline 130 is arranged circumferentially around the cleaning pipeline 130. The diameter d of the through holes 131 is 1 mm to 2 mm, for example, 1 mm, 1.2 mm, 1.5 mm or 1.8 mm, and the distance between the through holes 131 in the same layer is 0.5 mm to 1.5 mm, for example, 0.5 mm, 0.8 mm, 1.2 mm or 1.5 mm.

[0036] Figure 5 It is a schematic cross-sectional structure diagram of the cleaning pipeline in the cleaning device provided in this embodiment. As Figure 5As shown, the side wall of the cleaning pipeline 130 has a certain thickness, allowing the through hole 131 to be inclined. Specifically, the thickness of the side wall of the cleaning pipeline 130 is 3 mm to 4 mm. The through hole 131 penetrates the side wall of the cleaning pipeline 130 obliquely, and the downward inclination angle θ of the through hole 131 is 15 degrees to 60 degrees, for example, θ = 45 degrees. Preferably, the downward inclination angles θ of the through holes 131 in the same layer are the same. When purging gas is passed through the through holes 131 into the gap L between the rotary bearing 120 and the cleaning pipeline 130, the purging gas forms a conical radiation of air flow around the cleaning pipeline 130, preventing the air flow generated by the high-speed rotation of the rotary bearing 120 from bringing foreign matters into the gap L, and thus preventing foreign matters from being adsorbed on the back surface of the wafer 100 and contaminating the back surface of the wafer 100.

[0037] Furthermore, the downward inclination angles θ of the three layers of through holes 131 increase sequentially from bottom to top to strengthen layer by layer to block external foreign matters. Alternatively, the downward inclination angles θ of at least two of the three layers of through holes 131 are the same. Exemplarily, the two layers of through holes 131 close to the wafer 100 are arranged circumferentially around the cleaning pipeline 130. The two layers of through holes 131 are arranged in parallel and have the same downward inclination angle. The layer of through holes 131 close to the bottom of the cleaning pipeline 130 is arranged circumferentially around the cleaning pipeline 130, and the downward inclination angle is different from that of the two upper layers of through holes. For example, the downward inclination angle of the layer of through holes 131 close to the bottom of the cleaning pipeline 130 is smaller than that of the two upper layers of through holes. Of course, the downward inclination angles of the three layers of through holes 131 can also be the same. In addition, it should be noted that the present invention is not limited to the specific distribution of the through holes on the side wall of the cleaning pipeline. It can be more than three layers of distribution, not only limited to layer-by-layer spaced distribution, but also can be in other forms of matrix distribution.

[0038] A cleaning conduit leading to the back surface of the wafer 100 is provided in the cleaning pipeline 130. The cleaning conduit is connected to a cleaning reagent (Chemical) for cleaning the back surface of the wafer 100. A through hole 131 on the side wall of the cleaning pipeline 130 is connected to a gas pipeline (not shown in the figure), and the gas pipeline and the cleaning conduit are independent of each other. For example, the bottom of the cleaning pipeline 130 is connected to an N2 gas pipeline with a diameter of 1 / 2 to 3 / 8 inches, and N2 is blown into the gap L between the cleaning pipeline 130 and the rotary bearing 120. The flow rate of the N2 is 10 L / min to 20 L / min, such as 12 L / min, 16 L / min or 18 L / min. The flow rate of the N2 can be appropriately adjusted according to the downward inclination angle of the through hole to achieve the maximum blocking effect. In addition, in this embodiment, blowing gas into the gap L between the cleaning pipeline 130 and the rotary bearing 120 is mainly to form an air flow confrontation with the air flow generated by the high-speed rotation of the rotary bearing 120, blocking foreign objects from the outside or metal particles on the surface of the rotary bearing 120 from adhering to the back surface of the wafer 100. Therefore, in other embodiments of the present invention, the protective gas used to blow into the gap L can also be other inert gases or pure and dry air.

[0039] It should be noted that the cleaning device provided in this embodiment is applicable to cleaning machines with rotary bearings (spindles) and any other similar semiconductor process equipment, not limited to cleaning machines only. Any equipment using a spindle, if it is necessary to prevent particles from being contaminated on the back surface due to the siphon phenomenon caused by high-speed rotation, can apply the present invention, which will not be specifically elaborated here.

[0040] Correspondingly, the present invention also provides a cleaning method, which includes cleaning a wafer using the above cleaning device. Specifically, the carrier 110 in the cleaning device carries and fixes the wafer 100 to be cleaned. The rotary bearing 120 below the carrier 110 rotates to drive the wafer 100 to rotate at a certain speed. The cleaning pipeline 130 located in the middle of the rotary bearing 120 supplies a cleaning reagent to the back surface of the wafer. The through holes 131 distributed on the side wall of the cleaning pipeline 130 are connected to a gas pipeline, and a protective gas (bearing N2) is blown into the gap L between the cleaning pipeline 130 and the rotary bearing 120 to prevent the air flow generated by the high-speed rotation of the rotary bearing 120 from bringing foreign objects from the outside or metal particles on the surface of the rotary bearing 120 into the gap L and adsorbing them on the back surface of the wafer 100. This cleaning method can improve the particle and metal contamination on the wafer surface and avoid the adverse effects of metal contamination on the wafer surface on the products of subsequent processes.

[0041] Such as Figure 6As shown, after cleaning the wafer using the cleaning method provided in this embodiment, the cleaning effect on the back side of the wafer can be inspected in two ways: Method 1 and Method 2. Specifically, Method 1: Select a wafer (polished wafer), after cleaning it with a single wafer cleaning machine, use a Surface Scan (SPX) to collect the particle situation on the back side of the wafer, and at the same time perform SEM analysis on the particles. Method 2: Select a wafer (polished wafer), after cleaning it with a single wafer cleaning machine, perform high-temperature treatment or epitaxial growth, and use surface photovoltage (SPV) to test the content of bulk metal in the wafer body.

[0042] Regarding Method 1, Figure 7 It is a comparison chart (Backside Particle Comparison) of the particle conditions on the back side of the wafer after cleaning the wafer with an existing single wafer cleaning device and the cleaning device provided in the embodiment of the present invention. Among them, the number of sample wafers is greater than 25 (Sample wafer count >= 25 pcs). For particle sizes (PAR Size No) of 90 nm and 200 nm, the SPX test results show that after cleaning the wafer with the cleaning device provided in this embodiment, the number of particles (ParticleCount (ea / wafer)) on the back side of the wafer decreases from > 52 ea to less than 2 ea. SEM tests on the residual particles show that none of them contain Fe elements, which proves that the Bearing N2 for purging the side wall through holes of the cleaning pipeline in the cleaning device provided in this embodiment can effectively avoid the influence of foreign objects being sucked back to the wafer surface due to turbulent flow (air flow generated by high-speed rotation). That is, the cleaning device provided in this embodiment can effectively improve the particle conditions on the back side of the wafer.

[0043] Regarding Method 2, Figure 8 It is a data comparison chart of the content of bulk metal in the wafer body obtained by SPV (surface photo voltage) testing of the epitaxial wafer grown after cleaning the wafer with an existing single wafer cleaning device and the cleaning device provided in the embodiment of the present invention. As Figure 8 shown, the SPV test results show that after cleaning the wafer with the cleaning device provided in the embodiment of the present invention, the data of Bulk Fe decreases from > 1E+10 atoms / cm3 to less than 0.49E+10 atoms / cm3, and the total content of other transition metals except Fe (Nr) decreases from > 3.7E+10 to less than 3.1E+10, which proves that the Bearing N2 for purging the side wall through holes of the cleaning pipeline in the cleaning device provided in this embodiment can effectively prevent the problem of foreign objects being sucked back to the wafer surface due to turbulent flow.

[0044] In summary, the present invention provides a cleaning device and a cleaning method, including a carrier table for carrying and fixing a wafer to be cleaned; a rotating bearing located under the carrier table for driving the carrier table to rotate; a cleaning pipeline located in the middle of the rotating bearing, with through holes provided on the side wall of the cleaning pipeline; and a gas pipeline connected to the through holes of the cleaning pipeline for purging a protective gas into the gap between the cleaning pipeline and the rotating bearing, so as to prevent foreign matters from being brought into the back surface of the wafer adsorbed through the gap by the airflow generated by the high-speed rotation of the rotating bearing. The present invention provides through holes on the side wall of the cleaning pipeline, and purges gas into the gap between the rotating bearing and the cleaning pipeline through the through holes, so as to prevent foreign matters from the outside or metal particles on the surface of the rotating bearing from being brought into and adsorbed on the back surface of the wafer by the airflow generated by the high-speed rotation of the rotating bearing, thereby improving the particle and metal contamination on the wafer surface and avoiding the adverse effects of metal contamination on the wafer surface on the products of subsequent processes.

[0045] It should be noted that each embodiment in this specification is described in a related manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the structural embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the related parts can refer to the partial description of the method embodiments.

[0046] The above description is only a description of the preferred embodiments of the present invention, and does not limit the scope of the present invention in any way. Any changes and modifications made by those of ordinary skill in the art of the present invention based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A cleaning device, characterized in that, Comprising: A carrier stage for carrying and fixing a wafer to be cleaned; A rotating bearing located under the carrier stage for driving the carrier stage to rotate; A cleaning pipeline located in the middle of the rotating bearing. Through holes are provided on the side wall of the cleaning pipeline, and the through holes are distributed at multiple layers at the middle and lower parts of the cleaning pipeline. The multiple layers of through holes are arranged in a spiral around the cleaning pipeline; A gas pipeline connected to the through holes of the cleaning pipeline for purging a protective gas into the gap between the cleaning pipeline and the rotating bearing to prevent foreign matters from being brought into the back surface of the wafer adsorbed through the gap by the airflow generated by the high-speed rotation of the rotating bearing.

2. The cleaning device according to claim 1, wherein The through hole obliquely penetrates the side wall of the cleaning pipeline.

3. The cleaning device according to claim 2, wherein The through hole inclines downward, and the downward inclination angle of the through hole is 15 degrees to 60 degrees.

4. The cleaning device according to claim 1, wherein, Each layer of the through holes is arranged circumferentially around the cleaning pipeline.

5. The cleaning device according to claim 3, characterized in that, The downward inclination angles of the through holes in the same layer are the same.

6. The cleaning device according to claim 5, characterized in that, The downward inclination angles of the through holes increase successively from bottom to top.

7. The cleaning device according to claim 1, wherein The flow rate of the protective gas is 10 L / min to 20 L / min.

8. A cleaning method, characterized in that, Including cleaning a wafer using the cleaning device according to any one of claims 1-7.

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