Semiconductor structure cleaning method

Abstract

A method for cleaning a semiconductor structure comprises: providing a substrate, the substrate comprising a functional surface and a back surface opposite to the functional surface; forming a fluid passivation film on the functional surface of the substrate; after forming the fluid passivation film, performing a first charge removal treatment on the surface of the functional surface of the substrate using a wet cleaning process; after performing the first charge removal treatment, performing a main cleaning on the surface of the substrate. The performance of the semiconductor structure after cleaning by the method is improved.

Description

Technical Field

[0001] The invention relates to the field of semiconductor manufacturing, and in particular to a method for cleaning a semiconductor structure. Background Art

[0002] During the manufacturing process of semiconductor chips, tiny foreign matter, metal impurities, and organic impurities will adhere to the semiconductor chips. Once these impurities adhere to the semiconductor wafer, they will cause malfunction. Therefore, the cleanliness of semiconductor chips is managed according to strict specifications to prevent these impurities from adhering. Moreover, with the miniaturization and high performance of semiconductor devices, the management requirements for foreign matter, metal impurities, and organic impurities have also become stricter. Generally speaking, these impurities can be removed by wet cleaning methods. Therefore, the cleaning technology of semiconductor chips has become a very important process in semiconductor technology.

[0003] The process of forming a semiconductor chip includes multiple plasma etching processes and ion implantation processes. The plasma etching process and ion implantation process easily generate a large amount of electric charge on the chip surface. In the subsequent wet cleaning process, it is easy to discharge quickly and form serious arc defects, causing great damage to the structure of the chip surface.

[0004] Therefore, how to remove the charge on the chip surface is an urgent problem to be solved. Summary of the invention

[0005] The technical problem solved by the invention is to provide a method for cleaning a semiconductor structure to remove the electric charges on the surface of a chip.

[0006] In order to solve the above technical problems, the technical solution of the present invention provides a method for cleaning a semiconductor structure, comprising: providing a substrate, the substrate comprising a functional surface and a back surface opposite to the functional surface; forming a fluid passivation film on the functional surface of the substrate; after forming the fluid passivation film, performing a first de-charge treatment on the surface of the functional surface of the substrate using a wet cleaning process; after performing the first de-charge treatment, performing a main cleaning on the surface of the substrate.

[0007] Optionally, the material of the fluid passivation film includes liquid; the liquid includes pure water or isopropyl alcohol.

[0008] Optionally, the process for forming the fluid passivation film includes a spraying process; the process parameters of the spraying process include: a rotation speed of 0 to 1200 rpm, a flow rate range of 0 to 2000 ml per minute, and a time of 0 to 5 minutes.

[0009] Optionally, the wet cleaning process includes a first stage and a second stage after the first stage. In the first stage, a liquid film formed by the solution of the wet cleaning process covers the surface of the fluid passivation film. In the second stage, the liquid film formed by the solution of the wet cleaning process dissolves with the fluid passivation film to form a mixed solution film. The mixed solution film is located on the surface of the functional surface of the substrate.

[0010] Optionally, the ratio of the thickness of the fluid passivation film to the thickness of the liquid film is in the range of 0 to 5:1.

[0011] Optionally, the thickness of the fluid passivation film ranges from 0 to 5 mm.

[0012] Optionally, the thickness of the fluid film ranges from 0 to 5 mm.

[0013] Optionally, the solution of the wet cleaning process includes a deionized water solution dissolved with carbon dioxide; the pH range of the wet cleaning process solution is 4 to 7, the conductivity range is 0 to 50 microsiemens per centimeter, the flow range is 0 ml per minute to 2000 ml per minute, the time is 0 to 5 minutes, and the rotation speed is 0 rpm to 1200 rpm.

[0014] Optionally, the material of the mixed solution membrane includes a deionized water solution dissolved with carbon dioxide; the pH range of the mixed solution membrane solution is 4 to 7, and the conductivity range is 0 to 40 microSiemens per centimeter.

[0015] Optionally, the solution of the wet cleaning process includes a deionized water solution dissolved with ammonia water; the pH range of the wet cleaning process solution is 7 to 11, the conductivity range is 0 to 50 microsiemens per centimeter, the flow range is 0 ml per minute to 2000 ml per minute, the time is 0 to 5 minutes, and the rotation speed is 0 rpm to 1200 rpm.

[0016] Optionally, the material of the mixed solution membrane includes a deionized water solution dissolved with ammonia water; the pH range of the mixed solution membrane solution is 7 to 11, and the conductivity range is 0 to 40 microSiemens per centimeter.

[0017] Optionally, the solution used for main cleaning of the substrate surface includes an acidic solution or an alkaline solution. Optionally, the substrate includes a base and a fin structure located on the base, and the surface of the fin structure is a functional surface of the substrate.

[0018] Optionally, the substrate includes: a base; a device layer located on the base, the surface of the device layer is the functional surface of the substrate, the device layer includes an isolation structure and a device structure located within the isolation structure, and the device structure includes a transistor, a diode, a triode, a capacitor, an inductor or a conductive structure.

[0019] Optionally, the substrate further includes: a dielectric layer located on the device layer; and a conductive layer located in the dielectric layer, wherein the conductive layer is electrically connected to the device structure, and a surface of the conductive layer is a functional surface of the substrate.

[0020] Optionally, before forming the fluid passivation film on the functional surface of the substrate, the method further includes: performing a second de-charge treatment on the back side of the substrate.

[0021] Optionally, the process of performing the second de-charge treatment on the surface of the substrate includes a wet cleaning process; the solution of the wet cleaning process includes a deionized water solution containing carbon dioxide or a deionized water solution containing ammonia.

[0022] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0023] The cleaning method of the technical solution of the present invention forms a fluid passivation film on the substrate before performing the first decharge treatment on the substrate surface. On the one hand, during the process of performing the first decharge treatment on the substrate surface, in the initial state, the fluid passivation film can form a capacitor structure with the liquid film formed by the substrate and the solution of the first decharge treatment, so that the process of the first decharge treatment is not easy to directly contact and react with the charge on the substrate surface, thereby generating discharge; on the other hand, as time goes by, the fluid passivation film can merge with the liquid film formed by the solution of the first decharge treatment, so that the fluid passivation film can dilute the solution concentration of the wet removal process, so that the conductivity of the formed mixed solution is reduced, thereby effectively preventing the rapid release of the charge on the substrate surface, making the charge release slower and safer, and not easy to generate arc defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figures 1 to 6 It is a process schematic diagram of a method for cleaning a semiconductor structure in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] As described in the background art, how to remove the charges on the chip surface is an urgent problem to be solved.

[0026] Specifically, the process of forming a semiconductor chip includes multiple plasma-containing etching processes and ion implantation processes. The plasma-containing etching process and ion implantation process easily generate a large amount of electric charge on the chip surface. In the subsequent wet cleaning process, the wet cleaning process solution usually has good conductivity. Therefore, the wet cleaning process solution easily reacts with the electric charge on the chip surface, thereby easily discharging quickly and forming serious arc defects, which greatly damages the structure of the chip surface and further affects the chip yield.

[0027] At present, deionized water (DICO2) with weaker conductivity and dissolved carbon dioxide is usually used to slowly release the surface charge on the back and front of the chip. After the surface charge is fully released, the chip surface is wet cleaned to reduce the degree of discharge and reduce arc defects.

[0028] However, the concentration of DICO2 in the entire factory is usually fixed, that is, its conductivity cannot be adjusted at will. At the same time, the surface charge of each layer in the chip manufacturing process varies. For some processes with high charge on the front layer, the method of using deionized water (DICO2) with weaker conductivity and dissolved carbon dioxide to slowly release the surface charge on the back and front of the chip has little effect, and a large number of arc defects will still occur, affecting the yield of the chip.

[0029] In order to solve the above problems, the technical solution of the present invention provides a method for cleaning a semiconductor structure, by forming a fluid passivation film on the substrate before performing a first decharge treatment on the substrate surface. On the one hand, the fluid passivation film can form a capacitor structure with the substrate and the liquid film of the first decharge treatment in the initial state during the process of performing the first decharge treatment on the substrate surface, so that the first decharge treatment process is not easy to directly contact and react with the charge on the substrate surface, thereby generating a discharge situation; on the other hand, as time goes by, the fluid passivation film can merge with the liquid film formed by the solution of the first decharge treatment, so that the fluid passivation film can dilute the solution concentration of the wet removal process, so that the conductivity of the formed mixed solution is reduced, thereby effectively preventing the rapid release of the charge on the substrate surface, making the charge release slower and safer, and not easy to generate arc defects.

[0030] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0031] Figures 1 to 6 It is a process schematic diagram of a method for cleaning a semiconductor structure in an embodiment of the present invention.

[0032] Please refer to Figure 1 , providing a substrate, wherein the substrate includes a functional surface 101 and a back surface 102 opposite to the functional surface 101.

[0033] In this embodiment, the substrate includes: a base 100; a device layer 103 located on the base, wherein the surface of the device layer 103 is the functional surface 101 of the substrate, and the device layer 103 includes an isolation structure (not shown) and a device structure (not shown) located within the isolation structure, and the device structure includes a transistor, a diode, a triode, a capacitor, an inductor or a conductive structure.

[0034] In this embodiment, the material of the substrate 100 is silicon.

[0035] In other embodiments, the material of the substrate includes silicon carbide, silicon germanium, a multinary semiconductor material composed of group III-V elements, silicon on insulator (SOI) or germanium on insulator (GOI). Among them, the multinary semiconductor material composed of group III-V elements includes InP, GaAs, GaP, InAs, InSb, InGaAs or InGaAsP.

[0036] In other embodiments, the substrate further includes: a dielectric layer located on the device layer; and a conductive layer located in the dielectric layer, wherein the conductive layer is electrically connected to the device structure, and a surface of the conductive layer is a functional surface of the substrate.

[0037] In other embodiments, the substrate includes a base and a fin structure located on the base, and a surface of the fin structure is a functional surface of the substrate.

[0038] Please refer to Figure 2 , a second de-charge treatment is performed on the back side 102 of the substrate.

[0039] In this embodiment, the process of performing the second de-charge treatment on the surface of the substrate includes a wet cleaning process; the solution of the wet cleaning process includes a deionized water solution containing carbon dioxide or a deionized water solution containing ammonia.

[0040] The deionized water (DICO2) solution containing carbon dioxide or the deionized water solution containing ammonia has a weak conductivity, and thus can slowly release the surface charge of the back side 102 of the substrate. After the surface charge is fully released, when the back side 102 of the substrate is subsequently cleaned, the rapid release of the surface charge of the substrate can be effectively prevented, making the release of the charge slower and safer, and less likely to cause arc defects.

[0041] In other embodiments, the second de-charge treatment may not be performed on the back side of the substrate.

[0042] Please refer to Figure 3 , a fluid passivation film 104 is formed on the substrate functional surface 101.

[0043] The material of the fluid passivation film 104 includes liquid; the liquid includes pure water or isopropyl alcohol.

[0044] In this embodiment, the material of the fluid passivation film 104 includes pure water. The pure water is not conductive, so the fluid passivation film 104 plays an insulating role on the substrate functional surface 101. Therefore, in the subsequent process of performing the first decharge treatment on the substrate surface, in the initial state, the liquid passivation film 104 can form a capacitor structure with the substrate and the liquid film of the first decharge treatment, so that the process of the first decharge treatment is not easy to directly contact and react with the charges on the substrate surface, thereby generating discharge.

[0045] The process of forming the fluid passivation film 104 includes a spray process; the process parameters of the spray process include: a rotation speed of 0 to 1200 rpm, a flow rate range of 0 to 2000 ml per minute, and a time of 0 to 5 minutes.

[0046] In this embodiment, the thickness of the fluid passivation film 104 is in the range of 0 to 5 mm.

[0047] After forming the fluid passivation film 104, a wet cleaning process is used to perform a first de-charge treatment on the surface of the substrate functional surface 101. For the process of performing the first de-charge treatment on the surface of the substrate functional surface 101, please refer to Figure 4 and Figure 5 .

[0048] The wet cleaning process includes a first stage and a second stage after the first stage.

[0049] Please refer to Figure 4 In the first stage, a liquid film 105 formed by the solution of the wet cleaning process covers the surface of the fluid passivation film 104 .

[0050] In this embodiment, the solution of the wet cleaning process includes a deionized water solution dissolved with carbon dioxide; the pH range of the wet cleaning process solution is 4 to 7, the conductivity range is 0 to 50 microsiemens per centimeter, the flow range is 0 ml per minute to 2000 ml per minute, the time is 0 to 5 minutes, and the rotation speed is 0 rpm to 1200 rpm.

[0051] The deionized water solution containing carbon dioxide is conductive, so that the liquid passivation film 104 can form a capacitor structure with the liquid film 105 formed by the substrate and the solution of the wet cleaning process, so that the first decharge treatment process is not easy to directly contact and react with the charges on the surface of the substrate, thereby generating discharge.

[0052] In this embodiment, the ratio of the thickness of the fluid passivation film 104 to the thickness of the liquid film 105 is in the range of 0 to 5:1. The thickness of the liquid film 105 is in the range of 0 to 5 mm.

[0053] The process parameters of the above-mentioned wet cleaning process can make the ratio of the thickness of the formed fluid passivation film 104 to the thickness of the liquid film 105 range from 0 to 5:1, thereby ensuring that the conductivity of the mixed solution film formed after the subsequent liquid film 105 is diluted with pure water is reduced, thereby effectively preventing the rapid release of surface charges on the substrate, making the release of charges slower and safer, and less likely to cause arc defects.

[0054] In other embodiments, the solution of the wet cleaning process includes a deionized water solution dissolved with ammonia water; the pH range of the wet cleaning process solution is 7 to 11, the conductivity range is 0 to 50 microsiemens per centimeter, the flow range is 0 ml per minute to 2000 ml per minute, the time is 0 to 5 minutes, and the rotation speed is 0 rpm to 1200 rpm.

[0055] Please refer to Figure 5 In the second stage, the liquid film 105 formed by the solution of the wet cleaning process dissolves with the fluid passivation film 104 to form a mixed solution film 106 , and the mixed solution film 106 is located on the surface of the substrate functional surface 101 .

[0056] In this embodiment, the material of the mixed solution membrane 106 includes a deionized water solution dissolved with carbon dioxide; the pH range of the mixed solution membrane solution is 4 to 7, and the conductivity range is 0 to 40 microSiemens per centimeter.

[0057] As time goes by, the fluid passivation film 104 can merge with the liquid film 105 formed by the solution of the wet cleaning process, so that the fluid passivation film 104 can dilute the concentration of the liquid film 105 formed by the solution of the wet cleaning process, so that the conductivity of the mixed solution film 106 solution is less than the conductivity of the liquid film 105 formed by the solution of the wet cleaning process. The conductivity of the mixed solution film 106 solution is low, so that the mixed solution film 106 solution has a smaller conductivity, which can effectively prevent the rapid release of surface charge on the substrate, making the release of charge slower and safer, and less likely to cause arc defects.

[0058] In other embodiments, the material of the mixed solution membrane includes a deionized water solution dissolved with ammonia water; the pH range of the mixed solution membrane solution is 7 to 11, and the conductivity range is 0 to 40 microSiemens per centimeter.

[0059] Please refer to Figure 6 After the first de-charge treatment, the substrate surface is mainly cleaned.

[0060] Since deionized water (DICO2) containing carbon dioxide having a weaker conductivity is first used to slowly release the surface charge on the back side and the functional surface of the substrate, the surface charge can be fully released. When the back side and the functional surface of the substrate are then cleaned, the degree of discharge between the main cleaning solution and the substrate surface is reduced, thereby reducing arc defects.

[0061] The solution for main cleaning of the substrate surface includes an acidic solution or an alkaline solution. The acidic solution and the alkaline solution are common cleaning solutions in the technical field, which are selected as needed in the specific process and will not be described in detail here.

[0062] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for cleaning a semiconductor structure, characterized in that: include: Providing a substrate, the substrate comprising a functional surface and a back surface opposite to the functional surface; A fluid passivation film is formed on the functional surface of the substrate by a spraying process, wherein the fluid passivation film is an insulating material; After forming the fluid passivation film, a first de-charge treatment is performed on the surface of the functional surface of the substrate by a wet cleaning process, wherein the wet cleaning process includes a first stage and a second stage after the first stage, wherein in the first stage, a liquid film formed by a solution of the wet cleaning process covers the surface of the fluid passivation film, and the fluid passivation film can form a capacitor structure with the substrate and the liquid film formed by the solution of the wet cleaning process; In the second stage, the liquid film formed by the solution of the wet cleaning process dissolves with the fluid passivation film to form a mixed solution film, the mixed solution film is located on the surface of the functional surface of the substrate, and the concentration of the liquid film is greater than the concentration of the mixed solution film; After the first charge removal treatment is performed, the substrate surface is mainly cleaned.

2. The semiconductor structure cleaning method according to claim 1, characterized in that: The material of the fluid passivation film includes liquid; the liquid includes pure water or isopropyl alcohol.

3. The semiconductor structure cleaning method according to claim 2, characterized in that: The process parameters of the spraying process include: a rotation speed of 0 rpm to 1200 rpm, a flow rate range of 0 ml / min to 2000 ml / min, and a time of 0 to 5 minutes.

4. The semiconductor structure cleaning method according to claim 1, wherein: The ratio of the thickness of the fluid passivation film to the thickness of the liquid film is in the range of 0 to 5:

1.

5. The semiconductor structure cleaning method according to claim 4, characterized in that: The thickness of the fluid passivation film ranges from 0 to 5 mm.

6. The semiconductor structure cleaning method according to claim 4, characterized in that: The thickness of the liquid film ranges from 0 to 5 mm.

7. The semiconductor structure cleaning method according to claim 1, wherein: The solution of the wet cleaning process includes a deionized water solution dissolved with carbon dioxide; the pH range of the wet cleaning process solution is 4-7, the conductivity range is 0-50 microsiemens per centimeter, the flow range is 0 ml per minute to 2000 ml per minute, the time is 0-5 minutes, and the rotation speed is 0 rpm to 1200 rpm.

8. The semiconductor structure cleaning method according to claim 1, wherein: The material of the mixed solution membrane includes a deionized water solution dissolved with carbon dioxide; the pH range of the mixed solution membrane solution is 4-7, and the conductivity range is 0-40 micro-Siemens per centimeter.

9. The semiconductor structure cleaning method according to claim 1, wherein: The solution of the wet cleaning process includes a deionized water solution dissolved with ammonia water; the pH range of the wet cleaning process solution is 7-11, the conductivity range is 0-50 microsiemens per centimeter, the flow range is 0 ml per minute to 2000 ml per minute, the time is 0-5 minutes, and the rotation speed is 0 rpm to 1200 rpm.

10. The semiconductor structure cleaning method according to claim 1, wherein: The material of the mixed solution membrane includes a deionized water solution dissolved with ammonia water; the pH range of the mixed solution membrane solution is 7-11, and the conductivity range is 0-40 micro-Siemens per centimeter.

11. The semiconductor structure cleaning method according to claim 1, wherein: The solution used for main cleaning of the substrate surface includes an acidic solution or an alkaline solution.

12. The semiconductor structure cleaning method according to claim 1, wherein: The substrate comprises a base and a fin structure located on the base, and a surface of the fin structure is a functional surface of the substrate.

13. The semiconductor structure cleaning method according to claim 1, wherein: The substrate comprises: a base; a device layer located on the base, wherein the surface of the device layer is the functional surface of the substrate, the device layer comprises an isolation structure and a device structure located within the isolation structure, and the device structure comprises a transistor, a diode, a triode, a capacitor, an inductor or a conductive structure.

14. The semiconductor structure cleaning method according to claim 13, wherein: The substrate further comprises: a dielectric layer located on the device layer; and a conductive layer located in the dielectric layer, wherein the conductive layer is electrically connected to the device structure, and a surface of the conductive layer is a functional surface of the substrate.

15. The semiconductor structure cleaning method according to claim 1, wherein: Before forming the fluid passivation film on the functional surface of the substrate, the method further includes: performing a second de-charge treatment on the back side of the substrate.

16. The semiconductor structure cleaning method according to claim 15, characterized in that: The process of performing the second de-charge treatment on the surface of the substrate includes a wet cleaning process; the solution of the wet cleaning process includes a deionized water solution dissolved with carbon dioxide or a deionized water solution dissolved with ammonia.

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