Wafer cleaning method
The polished wafer surface is cleaned by alternating spraying methods of hydrofluoric acid and DIO3, which solves the problem of poor cleaning effect after polishing, and effectively removes large particles and metal abrasive matrix, extends the service life of the brush and improves the cleaning efficiency. and stability.
Patent Information
- Application Number
- CN202310800183.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-30
- Publication Date
- 2024-12-31
AI Technical Summary
In the prior art, the wafer cleaning effect after polishing is poor, especially the difficulty of removing residual abrasive liquid, which affects the subsequent process and product yield.
The polished wafer surface is cleaned by alternating spraying methods of hydrofluoric acid and DIO3 to form a protective water film, remove large particles and metal and alkaline abrasive liquid matrix, thin the oxide layer, extend the service life of the brush and improve cleaning efficiency.
Effectively remove large particles and metal abrasive matrix on the wafer surface, reduce pollution to the brush, improve particle level and process stability, extend the service life of the brush, and improve the stability of the cleaning steps after polishing.
Smart Images
Figure CN119230381A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of wafer cleaning, and in particular to a wafer cleaning method. Background Art
[0002] In the wafer manufacturing process, post-polishing cleaning plays a key role in the cleanliness level of the wafer. Wafer cleaning mainly removes the residual grinding fluid and natural oxide layer on the wafer surface after chemical mechanical polishing (CMP). The grinding fluid mainly includes alkaline solvents, buffers, grinding colloid particles, etc.
[0003] In the prior art, there are two common post-polishing cleaning methods: tank cleaning and single-wafer brushing. Single-wafer brushing has the advantages of short process time, better cleaning effect, and less fragmentation. Especially after the production of 300mm wafers, it has gradually become the main method of post-polishing cleaning.
[0004] The conventional process flow of single-wafer scrubbing includes: wafer wetting, SC1 (a mixture of ammonia, hydrogen peroxide and water) scrubbing, DIW (deionized water) cleaning, DHF (hydrofluoric acid) and DIO3 (ozone deionized water) alternating cleaning, where the residual grinding fluid is removed by the SC1 scrubbing step, and the metal contamination and natural oxide layer on the surface are removed by alternating DHF and DIO3 cleaning. However, the effect of SC1 scrubbing is significantly affected by the previous process. The surface properties of wafers of different batches and doping types vary greatly, and the difficulty of cleaning residual grinding fluid varies. The particle cleaning effect after polishing often varies greatly, affecting the subsequent process and the yield of the final wafer product. Summary of the invention
[0005] The embodiment of the present application provides a wafer cleaning method to at least solve the problem of poor cleaning effect of residual grinding liquid on the wafer in the related art.
[0006] In a first aspect, an embodiment of the present application provides a wafer cleaning method for cleaning a polished wafer surface, comprising:
[0007] Spraying the surface of the wafer with hydrofluoric acid of a first preset concentration for a first preset time;
[0008] brushing the surface of the wafer after spraying in the brushing chamber;
[0009] The wafer surface after scrubbing is cleaned in a cleaning chamber.
[0010] In some embodiments, brushing the surface of the wafer after spraying in the brushing chamber includes:
[0011] Using DIW to spray the surface of the wafer after the spraying to form a protective water film on the surface of the wafer;
[0012] The wafer with the protective water film is placed into the scrubbing chamber for scrubbing.
[0013] In some embodiments, the first preset concentration is between 3000 ppm and 10000 ppm.
[0014] In some embodiments, the first preset time is between 5s and 30s.
[0015] In a second aspect, an embodiment of the present application further provides a wafer cleaning method for cleaning a polished wafer surface, comprising:
[0016] Alternately spraying the surface of the wafer with hydrofluoric acid of a first preset concentration and DIO3 of a second preset concentration;
[0017] brushing the surface of the wafer after spraying in the brushing chamber;
[0018] The wafer surface after scrubbing is cleaned in a cleaning chamber.
[0019] In some embodiments, brushing the surface of the wafer after spraying in the brushing chamber includes:
[0020] Using DIW to spray the surface of the wafer after the spraying to form a protective water film on the surface of the wafer;
[0021] The wafer with the protective water film is placed into the scrubbing chamber for scrubbing.
[0022] In some embodiments, the first preset concentration is between 3000 ppm and 10000 ppm.
[0023] In some embodiments, the spraying time of the hydrofluoric acid with the first preset concentration is between 5s and 30s each time.
[0024] In some embodiments, the second predetermined concentration is between 20 ppm and 30 ppm.
[0025] In some embodiments, the spraying time of DIO3 of the second preset concentration is between 10s and 15s each time.
[0026] In some embodiments, before alternately spraying the wafer surface with hydrofluoric acid of a first preset concentration and DIO3 of a second preset concentration, the method further includes:
[0027] The wafer surface is sprayed with SC1 for a second preset time.
[0028] In some embodiments, the second preset time is between 5s and 20s.
[0029] Compared with the prior art, the wafer cleaning method provided in the embodiment of the present application effectively removes large particles and metals on the wafer surface, alkaline polishing liquid matrix and thins the oxide layer on the wafer surface by means of alternating spraying of hydrofluoric acid, hydrofluoric acid and DIO3, reduces the contamination of the brush by metal and polishing liquid, and facilitates the exposure and removal of micron-level polishing particles, so as to extend the service life of the brush, improve the brushing efficiency and improve the particle level, and improve the stability of the process results of the post-polishing wafer cleaning step for different products.
[0030] 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
[0031] 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:
[0032] Figure 1 is a flow chart of a wafer cleaning method according to an embodiment of the present application;
[0033] Figure 2 is an experimental effect diagram of a wafer cleaning method according to an embodiment of the present application;
[0034] Figure 3 is a flow chart of a wafer cleaning method according to another embodiment of the present application;
[0035] Figure 4 This is an experimental effect diagram of a wafer cleaning method according to another embodiment of the present application. DETAILED DESCRIPTION
[0036] 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 the field without making creative work are within the scope of protection of the present application.
[0037] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the" and the like involved in this application do not indicate a quantitative limitation, and may represent the singular or plural. The terms "include", "comprise", "have" and any of their variations involved in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units inherent to these processes, methods, products or devices. "Multiple" involved in this application means greater than or equal to two. "And / or" describes the association relationship of associated objects, indicating that there may be three relationships, for example, "A and / or B" can represent: A exists alone, A and B exist at the same time, and B exists alone. The terms "first", "second", "third" and the like involved in this application are only used to distinguish similar objects, and do not represent a specific ordering of objects.
[0038] The present invention provides a wafer cleaning method for cleaning a polished wafer surface. Figure 1 is a flow chart of a wafer cleaning method according to an embodiment of the present application, such as Figure 1 As shown, the method comprises the following steps:
[0039] Step S101 , spraying hydrofluoric acid of a first preset concentration on the surface of a wafer for a first preset time.
[0040] like Figure 2 As shown, Figure 2 The vertical axis in represents the number of LPD particles remaining on the wafer surface, in units of ea, and LPD stands for Light Point Defect. Figure 2 A1 represents the number of particles on the surface of the nitrogen (N)-doped wafer after the single-wafer cleaning or trough-type cleaning in the prior art described in the background technology, A2 represents the number of particles on the surface of the phosphorus (P)-doped wafer after the single-wafer cleaning or trough-type cleaning in the prior art described in the background technology, and A3 represents the number of particles on the surface of the sulfur (S)-doped wafer after the single-wafer cleaning or trough-type cleaning in the prior art described in the background technology. Figure 2 B1 represents the number of particles on the surface of the nitrogen (N)-doped wafer after cleaning by the wafer cleaning method in the embodiment of the present application, B2 represents the number of particles on the surface of the phosphorus (P)-doped wafer after cleaning by the wafer cleaning method in the embodiment of the present application, and B3 represents the number of particles on the surface of the sulfur (S)-doped wafer after cleaning by the wafer cleaning method in the embodiment of the present application. Figure 2Phosphorus (P), sulfur (S), and nitrogen (N) in the table refer to wafer products heavily doped with phosphorus (P), sulfur (S), and nitrogen (N).
[0041] Depend on Figure 2 It can be seen that before the wafer is scrubbed, the LPD particles on the wafer surface can be effectively removed by pre-treating the wafer with hydrofluoric acid. At the same time, hydrofluoric acid can also effectively remove the metal and alkaline polishing liquid matrix on the wafer surface and thin the oxide layer on the wafer surface. It can also reduce the subsequent contamination of the metal and polishing liquid on the brush for scrubbing the wafer to a certain extent, and facilitate the exposure and removal of micron-level polishing particles.
[0042] Step S102, scrubbing the wafer surface after spraying in a scrubbing chamber.
[0043] In this step, after the wafer surface is sprayed with hydrofluoric acid, it is brushed to reduce the contamination of the brush by metal and grinding liquid, and to facilitate the exposure and removal of micron-sized grinding particles.
[0044] Step S103, cleaning the wafer surface after scrubbing in a cleaning chamber.
[0045] Through the above steps S101 to S103, before the wafer is scrubbed, hydrofluoric acid is used to spray the wafer surface, which can effectively remove large particles of metal and alkaline polishing liquid matrix on the wafer surface and thin the oxide layer on the wafer surface, reduce the contamination of the brush by metal and polishing liquid, and facilitate the exposure and removal of micron-level polishing particles, so as to extend the service life of the brush, improve the scrubbing efficiency and improve the particle level, and improve the stability of the process results of the post-polishing wafer cleaning step for different products, especially heavily doped products such as phosphorus, sulfur, and nitrogen.
[0046] In some of the embodiments, brushing the wafer surface after spraying in the brushing chamber includes: spraying the wafer surface after spraying with DIW to form a protective water film on the wafer surface; placing the wafer with the protective water film into the brushing chamber for brushing.
[0047] In this embodiment, after the hydrofluoric acid spray treatment, DIW is used for cleaning to remove the grinding liquid and form a water film protection on the wafer surface so that the wafer is wet when entering the scrubbing chamber, thereby ensuring the stability of the wafer surface properties and achieving better particle removal effect during scrubbing.
[0048] In some embodiments, the first predetermined concentration is between 3000 ppm and 10000 ppm.
[0049] It should be noted that, in some embodiments, as the concentration increases, the particles on the wafer surface continue to decrease, and a better particle removal effect can be achieved.
[0050] In some embodiments, the first preset time is between 5s and 30s.
[0051] It should be noted that, in some embodiments, as time goes by, the particles on the wafer surface continue to decrease, and a better particle removal effect can be achieved.
[0052] This embodiment also provides a wafer cleaning method for cleaning the surface of a polished wafer. Figure 3 is a flow chart of a wafer cleaning method according to an embodiment of the present application, such as Figure 3 As shown, the method comprises the following steps:
[0053] Step S301: alternately spraying the wafer surface with hydrofluoric acid of a first preset concentration and DIO3 of a second preset concentration.
[0054] like Figure 4 As shown, Figure 4 The vertical axis in represents the number of LPD particles remaining on the wafer surface, in units of ea, and LPD stands for Light Point Defect. Figure 4 A1 represents the number of particles on the surface of the nitrogen (N)-doped wafer after the single-wafer cleaning or trough-type cleaning in the prior art described in the background technology, A2 represents the number of particles on the surface of the phosphorus (P)-doped wafer after the single-wafer cleaning or trough-type cleaning in the prior art described in the background technology, and A3 represents the number of particles on the surface of the sulfur (S)-doped wafer after the single-wafer cleaning or trough-type cleaning in the prior art described in the background technology. Figure 4 C1 represents the number of particles on the surface of the nitrogen (N)-doped wafer after cleaning by the wafer cleaning method in the embodiment of the present application, C2 represents the number of particles on the surface of the phosphorus (P)-doped wafer after cleaning by the wafer cleaning method in the embodiment of the present application, and C3 represents the number of particles on the surface of the sulfur (S)-doped wafer after cleaning by the wafer cleaning method in the embodiment of the present application. Figure 2 Phosphorus (P), sulfur (S), and nitrogen (N) in the table refer to wafer products heavily doped with phosphorus (P), sulfur (S), and nitrogen (N).
[0055] Depend on Figure 4 It can be seen that before the wafer is scrubbed, pre-treatment of the wafer with hydrofluoric acid can effectively remove large particles and metal and alkaline polishing liquid matrix on the wafer surface and thin the oxide layer on the wafer surface. At the same time, it can also reduce the subsequent contamination of the brush for scrubbing the wafer by metal and polishing liquid to a certain extent, and facilitate the exposure and removal of micron-level polishing particles.
[0056] Step S302, scrubbing the wafer surface after spraying in a scrubbing chamber.
[0057] In this step, after the wafer surface is sprayed with hydrofluoric acid, it is brushed to reduce the contamination of the brush by metal and grinding liquid, and to facilitate the exposure and removal of micron-sized grinding particles.
[0058] Step S303, cleaning the wafer surface after scrubbing in the cleaning chamber.
[0059] Through the above steps S301 to S303, before the wafer is scrubbed, hydrofluoric acid is used to spray the wafer surface, which can effectively remove the number of LPD particles on the wafer surface. At the same time, hydrofluoric acid can also effectively remove the metal and alkaline polishing liquid matrix on the wafer surface and thin the oxide layer on the wafer surface, reduce the pollution of the brush by metal and polishing liquid, and facilitate the exposure and removal of micron-level polishing particles, so as to extend the service life of the brush, improve the scrubbing efficiency and improve the particle level, and improve the stability of the process results of the post-polishing wafer cleaning step for different products, especially heavily doped products such as phosphorus, sulfur, and nitrogen.
[0060] In this embodiment, Figure 1 Based on the wafer cleaning method in , DIO3 treatment is added, and DHF and DIO3 are used to spray alternately for more effective pre-cleaning treatment. Figure 2 and Figure 4 The alternating spraying of DHF and DIO3 can improve the final particle level more significantly, and the pretreatment method of alternating spraying of DHF and DIO3 can weaken the adhesion between the grinding liquid and the wafer surface, thereby increasing the brushing effect of the subsequent brush and improving the number of particles on the surface of wafer products of different doping types such as N, P, and S.
[0061] In some of the embodiments, brushing the wafer surface after spraying in the brushing chamber includes: spraying the wafer surface after spraying with DIW to form a protective water film on the wafer surface; placing the wafer with the protective water film into the brushing chamber for brushing.
[0062] In this embodiment, after the hydrofluoric acid and DIO3 are sprayed alternately, DIW is used for cleaning to remove the liquid and form a water film protection on the wafer surface so that the wafer is moistened when entering the scrubbing chamber, thereby ensuring the stability of the wafer surface properties and achieving better particle removal effect during scrubbing.
[0063] In some embodiments, the first preset concentration is between 3000 ppm and 10000 ppm. It should be noted that, in some embodiments, as the concentration increases, the particles on the wafer surface continue to decrease, and a better particle removal effect can be achieved.
[0064] In some embodiments, during the alternate spraying of hydrofluoric acid and DIO3, the duration of each hydrofluoric acid spraying is between 5s and 30s. It should be noted that in some embodiments, as time goes by, the particles on the wafer surface continue to decrease, and a better particle removal effect can be achieved.
[0065] In some embodiments, the second preset concentration is between 20 ppm and 30 ppm. In this embodiment, as the concentration increases, the particles on the surface of the wafer continue to decrease, and a better particle removal effect can be achieved.
[0066] In some of the embodiments, the spraying time of DIO3 of the second preset concentration is between 10s and 15s each time. In this embodiment, as time goes by, the particles on the surface of the wafer continue to decrease, and a better particle removal effect can be achieved. It should be noted that the oxidation capacity of DIO3 of different concentrations is different. When the concentration of DIO3 is 20ppm, the spraying time can be set to 15s; when the concentration of DIO3 is 30ppm, the spraying time can be set to 10s.
[0067] By the above method, DHF and DIO3 can be sprayed alternately to remove some particles in advance, as follows
[0068] Table 1, thereby reducing the pollution to the brush, extending the service life of the brush and improving the cleaning effect.
[0069]
[0070] It should be noted that A represents the single-piece brushing or trough brushing method of the prior art described in the background technology, and C represents the single-piece brushing or trough brushing method of the present application. Figure 3 Wafer cleaning method in.
[0071] In some of the embodiments, before alternately spraying the wafer surface with hydrofluoric acid of the first preset concentration and DIO3 of the second preset concentration, SC1 may be further used to spray the wafer surface for a second preset time.
[0072] After the wafer is polished, not only will a large amount of polishing liquid containing micron- and nanometer-sized particles remain on the front of the wafer, but the resin wax required for chip mounting will also remain on the back of the wafer, which makes it difficult to clean. When there is residual wax on the back of the wafer, the oxide layer on the back of the wafer will be covered by the residual wax, which will cause uneven etching on the back of the wafer.
[0073] Therefore, in this embodiment, by using SC1 to spray the wafer surface for the second preset time, the residual wax on the wafer surface can be removed to avoid uneven etching on the back side of the wafer.
[0074] In some embodiments, the second preset time is between 5s and 20s.
[0075] In this embodiment, as time goes by, the particles on the wafer surface continue to decrease, and a better particle removal effect can be achieved.
[0076] 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.
[0077] 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 for cleaning a polished wafer surface, characterized in that: include: Spraying the surface of the wafer with hydrofluoric acid of a first preset concentration for a first preset time; brushing the surface of the wafer after spraying in the brushing chamber; The wafer surface after scrubbing is cleaned in a cleaning chamber.
2. The wafer cleaning method according to claim 1, characterized in that: Brushing the surface of the wafer after spraying in the brushing chamber includes: Using DIW to spray the surface of the wafer after the spraying to form a protective water film on the surface of the wafer; The wafer with the protective water film is placed into the scrubbing chamber for scrubbing.
3. The wafer cleaning method according to claim 1, characterized in that: The first preset concentration is between 3000 ppm and 10000 ppm.
4. The wafer cleaning method according to claim 1, characterized in that: The first preset time is between 5s and 30s.
5. A wafer cleaning method for cleaning a polished wafer surface, characterized in that: include: Alternately spraying the surface of the wafer with hydrofluoric acid of a first preset concentration and DIO3 of a second preset concentration; brushing the surface of the wafer after spraying in the brushing chamber; The wafer surface after scrubbing is cleaned in a cleaning chamber.
6. The wafer cleaning method according to claim 5, characterized in that: Brushing the surface of the wafer after spraying in the brushing chamber includes: Using DIW to spray the surface of the wafer after the spraying to form a protective water film on the surface of the wafer; The wafer with the protective water film is placed into the scrubbing chamber for scrubbing.
7. The wafer cleaning method according to claim 5, characterized in that: The first preset concentration is between 3000 ppm and 10000 ppm.
8. The wafer cleaning method according to claim 5, characterized in that: The spraying time of the hydrofluoric acid with the first preset concentration is between 5s and 30s each time.
9. The wafer cleaning method according to claim 5, characterized in that: The second preset concentration is between 20 ppm and 30 ppm.
10. The wafer cleaning method according to claim 5, characterized in that: The spraying time of DIO3 of the second preset concentration is between 10s and 15s each time.
11. The wafer cleaning method according to claim 5, characterized in that: Before alternately spraying the wafer surface with hydrofluoric acid of a first preset concentration and DIO3 of a second preset concentration, the method further includes: The wafer surface is sprayed with SC1 for a second preset time.
12. The wafer cleaning method according to claim 11, characterized in that: The second preset time is between 5s and 20s.