Preparation method of groove structure in discrete device and discrete device

Abstract

The invention discloses a preparation method of a groove structure in a discrete device and the discrete device, and is applied to the field of semiconductor manufacturing. The device prefabricated member comprises a substrate and a patterned mask layer, the front surface of the substrate is provided with a groove structure prepared by using the patterned mask layer, and the patterned mask layer only comprises film layers made of the same material; performing polishing treatment on the front surface of the device prefabricated member by using a chemical mechanical polishing process until the patterned mask layer and a part of thickness of the substrate are removed, and forming a part of thickness of a damaged layer; and preparing a reaction layer which reacts with the damaged layer to generate a reaction layer to be removed, and then removing the generated reaction layer to be removed. The patterned mask layer is used for preparing the groove structure, the chemical mechanical polishing process is used for removing the patterned mask layer and residual metal ions, the reaction layer is prepared to react with the damaged layer, and the reaction layer to be removed is generated and removed, so that the preparation conciseness of the groove structure can be ensured, and meanwhile, the preparation yield of the device is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to a method for preparing a groove structure in a discrete device and the discrete device. Background Art

[0002] In the current preparation process of discrete devices, the method has always been to use a stacked film with an ONO structure (the ONO structure is a stacked structure formed by sequentially stacked oxide layers, nitride layers, and oxide layers) as a mask for graphic preparation design. When removing this traditional preparation method, the corresponding mechanical grinding requires a silicon nitride layer as a stop layer, and then other processes are used to remove the remaining mask layer. During this period, cumbersome process steps are required, and there is also a risk of incomplete removal of silicon nitride. The mask in the preparation process of discrete devices is set to not include a silicon nitride layer, but only consist of a film layer. On the one hand, grinding and removing the film layer is prone to cause surface damage. On the other hand, the process of removing the film layer generally requires the use of a grinding liquid, and metal ions in the grinding liquid will remain on the surface of the discrete device, resulting in abnormal threshold voltage problems in the discrete device.

[0003] Therefore, how to provide a method for preparing a groove structure in a discrete device, which only requires one film layer as a mask and can avoid surface damage and contamination during the preparation process of the discrete device, is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0004] In view of this, an object of the present invention is to provide a method for preparing a groove structure in a discrete device and a discrete device, which solves the problem in the prior art that the mask layer is composed of only one film layer, and grinding and removing the film layer is prone to cause surface damage on the one hand, and on the other hand, the process of removing the film layer generally requires the use of a grinding liquid, and metal ions in the grinding liquid will remain on the surface of the discrete device, resulting in abnormal threshold voltage of the discrete device.

[0005] In order to solve the above technical problems, the present invention provides a method for preparing a trench structure in a discrete device, comprising:

[0006] A device preform is provided; the device preform comprises a substrate, and a patterned mask layer located on the front side of the substrate, the front side of the substrate is provided with a groove structure formed by using the patterned mask layer and forming a depression toward the back side of the substrate, and the patterned mask layer comprises only a film layer of the same material;

[0007] Polishing the front side of the device preform by using a chemical mechanical polishing process until the patterned mask layer and a partial thickness of the substrate are removed to obtain a first device to be processed; after the front side of the substrate in the first device to be processed is polished, a partial thickness damage layer is formed;

[0008] Prepare a reaction layer on the front side of the first device to be processed, so that the reaction layer reacts with the damaged layer in the first device to be processed to generate a reaction layer to be removed, thereby obtaining a second device to be processed;

[0009] The reaction layer to be removed in the second device to be processed is removed to complete the preparation of the trench structure in the discrete device.

[0010] Optionally, the groove structure arranged on the front surface of the substrate is a shielding grid groove structure;

[0011] The shielding gate groove structure is provided with a functional layer and an isolation protection layer located on the front side of the functional layer and prepared by a high-density plasma chemical vapor deposition process.

[0012] Optionally, the front surface of the device preform is polished by a chemical mechanical polishing process until the patterned mask layer and a portion of the thickness of the substrate are removed to obtain a first device to be processed, comprising:

[0013] The front side of the device preform is polished by using a chemical mechanical polishing process until the isolation protection layer and the patterned mask layer on the front side of the substrate are removed, and a portion of the thickness of the substrate is removed to obtain the first device to be processed.

[0014] Optionally, the grinding liquid in the chemical mechanical polishing process is a grinding liquid containing cerium oxide slurry.

[0015] Optionally, after obtaining the first device to be processed, the method further includes:

[0016] A wet etching process is used to remove a portion of the thickness of the isolation protection layer in the shielding gate trench structure.

[0017] Optionally, preparing a reaction layer on the front surface of the first device to be processed so that the reaction layer reacts with the damaged layer in the first device to be processed to generate a reaction layer to be removed, thereby obtaining a second device to be processed, comprising:

[0018] A sacrificial oxide layer is prepared on the front surface of the first device to be processed by a deposition process, so that the sacrificial oxide layer reacts with the damaged layer in the first device to be processed to generate an oxide layer to be removed, thereby obtaining the second device to be processed.

[0019] Optionally, the substrate is a silicon substrate;

[0020] The oxide layer to be removed is a damaged layer formed in the silicon substrate, and is a silicon oxide layer to be removed generated by reacting with the sacrificial oxide layer.

[0021] Optionally, providing a device prefabricated part includes:

[0022] Providing an initial substrate, and preparing a mask layer on the front side of the initial substrate; the mask layer only includes a film layer of the same material;

[0023] Etching the area of ​​the mask layer corresponding to the preparation of the groove structure until the front surface of the initial substrate is exposed to obtain the patterned mask layer;

[0024] The initial substrate is etched along the front surface of the initial substrate exposed by the patterned mask layer toward the reverse surface of the initial substrate to form the groove structure as the device preform.

[0025] Optionally, the patterned mask layer includes only one oxide film layer.

[0026] The present invention also provides a discrete device, which is prepared by the above-mentioned method for preparing a groove structure in a discrete device, and comprises the substrate;

[0027] The front surface of the substrate is provided with the groove structure recessed toward the back surface of the substrate.

[0028] It can be seen that the method for preparing a groove structure in a discrete device provided by the present invention includes providing a device preform, the device preform includes a substrate, and a patterned mask layer located on the front side of the substrate, the front side of the substrate is provided with a groove structure prepared by using the patterned mask layer and forming a recess toward the reverse side of the substrate, and the patterned mask layer only includes a film layer of the same material; the front side of the device preform is polished by using a chemical mechanical polishing process until the patterned mask layer and a partial thickness of the substrate are removed to obtain a first device to be processed, and the front side of the substrate in the first device to be processed is polished to form a partial thickness of the damage layer; a reaction layer is prepared on the front side of the first device to be processed so that the reaction layer reacts with the damage layer in the first device to be processed to generate a reaction layer to be removed, and a second device to be processed is obtained; the reaction layer to be removed in the second device to be processed is removed to complete the preparation of the groove structure in the discrete device. The present invention prepares a groove structure in a substrate by using a patterned mask layer that only includes a film layer of the same material, which can reduce the complexity of preparing and removing the mask layer, thereby improving the simplicity of preparing the groove structure. At the same time, a chemical mechanical polishing process is used to remove the patterned mask layer and a partial thickness of the substrate, which can remove metal ions remaining in the grinding liquid on the surface of the substrate, and a reaction layer is prepared to react with a damaged layer generated by the substrate during polishing to generate a reaction layer to be removed and remove it, which can eliminate the damage to the substrate caused by polishing, thereby reducing the complexity of preparation while ensuring the yield rate of groove preparation.

[0029] In addition, the present invention also provides a discrete device, which is prepared by the above-mentioned method for preparing a groove structure in a discrete device and also has the above-mentioned beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0031] Figure 1 A flow chart of a method for preparing a trench structure in a discrete device provided by an embodiment of the present invention;

[0032] Figure 2 A schematic diagram of a structure of preparing grooves in a discrete device using an existing mask layer with an ONO structure;

[0033] Figures 3 to 8 An example flow chart of a method for preparing a trench structure in a discrete device provided by an embodiment of the present invention;

[0034] Figures 2 to 8 In the figure, the reference numerals are described as follows:

[0035] 1-mask layer of ONO structure, 2-metal ions, 3-damage layer;

[0036] 10-substrate, 20-groove structure, 30-patterned mask layer, 40-reaction layer, 50-functional layer, 60-isolation protection layer. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] In the process of preparing trench structures or other patterned structures, existing discrete devices have always used a stacked film with an ONO structure as a mask layer, and formed a patterned mask layer by processing the mask layer, and then used the patterned mask layer to prepare the patterned structure. In this traditional preparation method, when removing the patterned mask layer, the corresponding mechanical grinding generally uses the silicon nitride layer as a stop layer, and then the remaining patterned mask layer is removed using a corresponding process. It can be seen that whether it is the preparation of the patterned mask layer or the removal of the patterned mask layer, cumbersome process steps are required, and there is also a risk of incomplete removal of silicon nitride.

[0039] In order to solve the problem of many steps and complex process in the above process, the mask layer in the preparation process of the discrete device can be set to not include the silicon nitride layer, and only be formed by a film layer, which can shorten the preparation and removal process of the above mask layer. However, when grinding and removing the mask layer formed by the film layer, it generally stops on the surface of the substrate. On the one hand, it is easy to cause damage to the polishing stop surface of the discrete device. On the other hand, the process of removing the film layer by polishing process generally requires the use of grinding fluid, and metal ions in the grinding fluid will remain on the polishing stop surface of the discrete device, causing electrical abnormalities in the discrete device.

[0040] The present invention prepares a groove structure in a substrate by using a patterned mask layer that only includes a film layer of the same material, which can reduce the complexity of preparing and removing the mask layer, thereby improving the simplicity of preparing the groove structure. At the same time, a chemical mechanical polishing process is used to remove the patterned mask layer and a partial thickness of the substrate, which can remove metal ions remaining in the grinding liquid on the surface of the substrate, and a reaction layer is prepared to react with a damaged layer generated by the substrate during polishing to generate a reaction layer to be removed and remove it, which can eliminate the damage to the substrate caused by polishing, thereby reducing the complexity of preparation while ensuring the yield rate of groove preparation.

[0041] Please refer to Figure 1 , Figure 1 A flow chart of a method for preparing a trench structure in a discrete device provided by an embodiment of the present invention. The method may include:

[0042] S101: Provide a device preform; the device preform includes a substrate 10 and a patterned mask layer 30 located on the front side of the substrate 10, the front side of the substrate 10 is provided with a groove structure 20 prepared by using the patterned mask layer 30 and forming a recess toward the reverse side of the substrate 10, and the patterned mask layer 30 only includes a film layer of the same material.

[0043] It should be noted that the discrete device in this embodiment is an electronic component made of a semiconductor material with a single function or a specific function. The existing preparation of the trench structure 20 is generally prepared using an ONO structure mask layer, such as Figure 2 As shown, Figure 2 FIG. 1 is a schematic diagram of a structure of preparing a groove in a discrete device using an existing mask layer of an ONO structure. Figure 2 As shown in. The preparation method in this application can refer to Figures 3 to 8 , Figures 3 to 8A flowchart of a method for preparing a groove structure 20 in a discrete device provided in an embodiment of the present invention. In this embodiment, a device preform is provided including a substrate 10, and a groove structure 20 is formed on the front of the substrate 10, and the groove structure 20 is prepared using the above-mentioned graphic mask layer 30, and the mask layer is provided to be formed only by a film layer of the same material, which can ensure the convenience of mask layer preparation and shorten the mask preparation process and mask removal process. This embodiment does not limit the specific material of the mask layer, as long as it can be used to prepare the above-mentioned groove structure 20. In a feasible embodiment, the above-mentioned mask layer can be formed by an oxide film layer, or the mask layer can also be set to a nitride film layer or a polysilicon film layer, specifically silicon oxide or silicon nitride. In this embodiment, the groove structure 20 can be filled with corresponding materials, or the groove structure 20 can be not filled with any material.

[0044] S102: polishing the front side of the device preform by chemical mechanical polishing process until the patterned mask layer 30 and a partial thickness of the substrate 10 are removed to obtain a first device to be processed; after polishing, the front side of the substrate 10 in the first device to be processed forms a partial thickness damaged layer 3.

[0045] In this embodiment, the patterned mask layer 30 and a part of the thickness of the substrate 10 are removed by a chemical mechanical polishing process. It should be noted that when polishing to the surface of the substrate 10, that is, only the patterned mask layer 30 is removed, since the chemical mechanical polishing process requires the use of abrasive liquid, and the substances in the abrasive liquid react with the materials on the surface of the substrate 10 to generate soluble substances and insoluble residues. These insoluble residues include metal ions 2. In order to avoid the above-mentioned metal ions 2 remaining on the surface of the substrate 10. The electrical properties, it is necessary to further perform a polishing process to remove a part of the thickness of the substrate 10 to remove the metal ions 2 remaining on the surface of the substrate 10. This process is an over-polishing process of the chemical mechanical polishing process. In addition, since the over-polishing process of the chemical mechanical polishing process will damage the substrate 10, damage will be generated in the partial thickness of the front side of the substrate 10, that is, a damaged layer 3 is formed.

[0046] S103: preparing a reaction layer 40 on the front surface of the first device to be processed, so that the reaction layer 40 reacts with the damaged layer 3 in the first device to be processed to generate a reaction layer to be removed, thereby obtaining a second device to be processed.

[0047] In this embodiment, a reaction layer 40 is prepared on the front side of the first device to be processed. The reaction layer 40 can react with the damaged layer 3 formed in the substrate 10 by over-polishing to generate a reaction layer to be removed. The reaction layer to be removed is a film layer generated after a chemical reaction between the reaction layer 40 and the damaged layer 3. In the actual process flow, if there is any remaining unreacted part in the prepared reaction layer 40, it will be removed together with the reaction layer to be removed later.

[0048] S104: removing the reaction layer to be removed in the second device to be processed, and completing the preparation of the trench structure 20 in the discrete device.

[0049] In this embodiment, the reaction layer to be removed in the second device to be processed is removed, and the damaged layer 3 in the substrate 10 is removed, so that after removing the patterned mask layer 30, there is no residue and damage on the surface of the substrate 10, and a film layer of one material is used as a mask layer to complete the preparation of the groove structure 20 in the discrete device, thereby improving the editability and yield rate of the preparation.

[0050] Furthermore, in order to improve the adaptability of the preparation of the groove structure 20, the groove structure 20 arranged on the front surface of the substrate 10 may be arranged as a shielding gate groove structure;

[0051] The shielding gate trench structure is provided with a functional layer 50 and an isolation protection layer 60 located on the front surface of the functional layer 50 and prepared by a high-density plasma chemical vapor deposition process.

[0052] It should be noted that in this embodiment, the trench structure 20 is set as a shielding gate trench structure, and at least the corresponding functional layer 50 needs to be filled in the shielding gate trench structure, and the isolation protection layer 60 needs to be prepared by a high-density plasma chemical vapor deposition process. The above-mentioned filling of the functional layer 50 and the isolation protection layer 60 in the shielding gate trench structure can be completed before the patterned mask layer 30 is removed, and then the patterned mask layer 30 and the isolation protection layer 60 located outside the shielding gate trench structure are removed together.

[0053] Further, in order to ensure the adaptability of the process, the front side of the device preform is polished by the chemical mechanical polishing process until the patterned mask layer 30 and a part of the thickness of the substrate 10 are removed to obtain the first device to be processed, which may include:

[0054] The front side of the device preform is polished by chemical mechanical polishing process until the isolation protection layer 60 and the patterned mask layer 30 on the front side of the substrate 10 are removed, and a part of the thickness of the substrate 10 is removed to obtain a first device to be processed.

[0055] It should be noted that the isolation protection layer 60 is prepared by the high-density plasma chemical vapor deposition process. The deposited isolation protection layer 60 will protrude from the top of the groove structure 20 and will form a deposition of the isolation protection layer 60 material on the surface of the patterned mask layer 30. Therefore, when the front side of the device preform is polished by the chemical mechanical polishing process, the isolation protection layer 60 material outside the groove structure 20 should be removed at the same time to ensure that the polishing process is successfully completed.

[0056] Furthermore, in order to ensure that the polishing liquid in the chemical mechanical polishing process improves the removal effect of the patterned mask layer 30, the polishing liquid in the chemical mechanical polishing process can be set to be a polishing liquid containing cerium oxide slurry.

[0057] It should be noted that the grinding liquid in the chemical mechanical polishing process in this embodiment is a grinding liquid containing cerium oxide slurry. The cerium oxide grinding liquid has good chemical stability, and the cerium oxide grinding liquid has high grinding efficiency and polishing effect, and can improve the polishing process efficiency.

[0058] Furthermore, in order to ensure that the remaining functional layer is arranged in the trench of the shielding layer, after obtaining the first device to be processed as described above, the following steps may also be included:

[0059] A partial thickness of the isolation protection layer 60 in the shielding gate trench structure is removed by a wet etching process.

[0060] In this embodiment, after obtaining the first device to be processed, a wet etching process can be used to remove a portion of the thickness of the isolation protection layer 60 in the shielding gate groove structure, so that the remaining functional layer can be prepared in the shielding gate groove structure, and the remaining functional layer is separated from the originally prepared functional layer 50 by the isolation protection layer 60 to avoid contact failure.

[0061] Further, in order to repair the damage in the substrate 10 by using the reaction layer 40 to react with the damaged layer 3 and remove the damaged layer 3, the above-mentioned preparation of the reaction layer 40 on the front side of the first device to be processed so that the reaction layer 40 reacts with the damaged layer 3 in the first device to be processed to generate a reaction layer to be removed, and obtain the second device to be processed, may include:

[0062] A sacrificial oxide layer is prepared on the front side of the first device to be processed by a deposition process, so that the sacrificial oxide layer reacts with the damaged layer 3 in the first device to be processed to generate an oxide layer to be removed, thereby obtaining a second device to be processed.

[0063] It should be noted that in this embodiment, the reaction layer 40 is set as a sacrificial oxide layer, and the prepared sacrificial oxide layer is used to react with the above-mentioned damaged layer 3 to generate an oxide layer to be removed. That is, at this time, the damaged part of the substrate 10 reacts with the sacrificial oxide layer to generate a new oxide layer, and then the generated oxide layer is removed by a removal process to repair the damage existing in the substrate 10 of the first device to be processed.

[0064] Furthermore, in order to ensure the adaptability of the above damage repair step, the above substrate 10 may be set as a silicon substrate;

[0065] The oxide layer to be removed is a silicon oxide layer to be removed which is generated by the reaction of the damaged layer 3 formed in the silicon substrate and the sacrificial oxide layer.

[0066] In this embodiment, the substrate 10 is set to be a silicon substrate. At this time, the damaged silicon substrate reacts with the sacrificial oxide layer to generate silicon oxide, and then the generated silicon oxide is removed to repair the damage in the silicon substrate and improve process adaptability.

[0067] Further, in a feasible embodiment, the providing of the device preform may include the following steps:

[0068] Step S11: providing an initial substrate, and preparing a mask layer on the front side of the initial substrate; the mask layer only includes a film layer of the same material;

[0069] Step S12: etching the area of ​​the mask layer corresponding to the trench structure 20 until the front surface of the initial substrate is exposed to obtain a patterned mask layer 30;

[0070] Step S13: etching the initial substrate along the front surface of the initial substrate exposed by the patterned mask layer 30 toward the back surface of the initial substrate to form a trench structure 20 as a device prefabricated part.

[0071] It should be noted that in this embodiment, a mask layer formed only of a film layer of the same material is used to prepare a patterned mask layer 30, and the patterned mask layer 30 is used to prepare the trench structure 20, which can shorten the trench etching process and improve processing efficiency.

[0072] Furthermore, in order to improve the adaptability of the patterned mask layer 30 , the patterned mask layer 30 may be configured to include only one oxide film layer.

[0073] In the present embodiment, the patterned mask layer 30 includes only one oxide film layer, which ensures the convenience of preparing the patterned mask layer 30 and shortens the preparation process, and ensures the adaptability of the patterned mask layer 30 .

[0074] The method for preparing the groove structure 20 in a discrete device provided by an embodiment of the present invention includes providing a device preform, the device preform including a substrate 10, and a patterned mask layer 30 located on the front side of the substrate 10, the front side of the substrate 10 is provided with a groove structure 20 prepared by using the patterned mask layer 30 and forming a depression toward the reverse side of the substrate 10, and the patterned mask layer 30 only includes a film layer of the same material; the front side of the device preform is polished by using a chemical mechanical polishing process until the patterned mask layer 30 and a partial thickness of the substrate 10 are removed to obtain a first device to be processed, and the front side of the substrate 10 in the first device to be processed is polished to form a partial thickness of the damage layer 3; a reaction layer 40 is prepared on the front side of the first device to be processed so that the reaction layer 40 reacts with the damage layer 3 in the first device to be processed to generate a reaction layer to be removed, and a second device to be processed is obtained; and the reaction layer to be removed in the second device to be processed is removed to complete the preparation of the groove structure 20 in the discrete device. The present invention prepares the groove structure 20 in the substrate 10 by using a patterned mask layer 30 that only includes a film layer of the same material, which can reduce the complexity of preparing and removing the mask layer, thereby improving the simplicity of preparing the groove structure 20. At the same time, the patterned mask layer 30 and a partial thickness of the substrate 10 are removed by a chemical mechanical polishing process, which can remove the metal ions 2 remaining in the grinding liquid on the surface of the substrate 10, and prepare a reaction layer 40 to react with the damaged layer 3 generated when the substrate 10 is polished to generate a reaction layer to be removed and remove it, which can eliminate the damage to the substrate 10 caused by polishing, thereby reducing the complexity of preparation while ensuring the yield rate of groove preparation.

[0075] In addition, in the embodiment of the present invention, the groove structure 20 is set as a shielding gate groove structure, and the corresponding functional layer 50 needs to be filled in the shielding gate groove structure, and the isolation protection layer 60 is prepared by a high-density plasma chemical vapor deposition process, thereby ensuring the adaptability of the preparation of the groove structure 20; when the front side of the device preform is polished by a chemical mechanical polishing process, the isolation protection layer 60 material outside the groove structure 20 is removed at the same time to ensure that the polishing process is completed smoothly; the grinding liquid in the chemical mechanical polishing process is set to be a grinding liquid containing cerium oxide slurry, and the cerium oxide grinding liquid has chemical stability and has high grinding efficiency and polishing effect, which can improve the efficiency of the polishing process; the isolation protection layer 60 of a part of the thickness in the shielding gate groove structure is removed by a wet etching process, and the remaining functional layer can be prepared in the shielding gate groove structure, thereby achieving The functionality of the isolation protection layer 60 is improved; the reaction layer 40 is set as a sacrificial oxide layer, and the prepared sacrificial oxide layer is used to react with the above-mentioned damaged layer 3 to generate an oxide layer to be removed, thereby improving the repair effect of the damaged layer 3 in the substrate 10; the substrate 10 is set as a silicon substrate, and the damaged silicon substrate reacts with the sacrificial oxide layer to generate silicon oxide, and then the generated silicon oxide is removed to repair the damage in the silicon substrate, thereby improving the adaptability of the process; a mask layer formed only by a film layer of the same material is used to prepare a patterned mask layer 30, and the patterned mask layer 30 is used to prepare a groove structure 20, which can shorten the groove etching process and improve the processing efficiency; the patterned mask layer 30 is set to include only one oxide film layer, which on the one hand ensures the convenience of preparing the patterned mask layer 30 and shortens the preparation process, and on the other hand can ensure the adaptability of the patterned mask layer 30.

[0076] The discrete device provided by the embodiment of the present invention is introduced below. The discrete device described below and the method for preparing the trench structure in the discrete device described above can be referred to each other.

[0077] The discrete device provided in this embodiment is prepared by the above-mentioned method for preparing the trench structure in the discrete device, and may include a substrate;

[0078] The front surface of the substrate is provided with a groove structure recessed toward the back surface of the substrate.

[0079] The discrete device in this embodiment is prepared by at least the following steps: providing a device preform, the device preform including a substrate and a patterned mask layer located on the front side of the substrate, the front side of the substrate being provided with a groove structure formed by using the patterned mask layer and forming a depression toward the back side of the substrate, the patterned mask layer only including a film layer of the same material; polishing the front side of the device preform using a chemical mechanical polishing process until the patterned mask layer and a partial thickness of the substrate are removed to obtain a first device to be processed, the front side of the substrate in the first device to be processed being polished to form a partial thickness of a damage layer; preparing a reaction layer on the front side of the first device to be processed so that the reaction layer reacts with the damage layer in the first device to be processed to generate a reaction layer to be removed, to obtain a second device to be processed; removing the reaction layer to be removed in the second device to be processed to complete the preparation of the groove structure in the discrete device.

[0080] The present invention prepares a groove structure in a substrate by using a patterned mask layer that only includes a film layer of the same material, which can reduce the complexity of preparing and removing the mask layer, thereby improving the simplicity of preparing the groove structure. At the same time, a chemical mechanical polishing process is used to remove the patterned mask layer and a partial thickness of the substrate, which can remove metal ions remaining in the grinding liquid on the surface of the substrate, and a reaction layer is prepared to react with a damaged layer generated by the substrate during polishing to generate a reaction layer to be removed and remove it, which can eliminate the damage to the substrate caused by polishing, thereby reducing the complexity of preparation while ensuring the yield rate of groove preparation.

[0081] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0082] In addition, it should be noted that, in this article, relationships such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0083] The above is a detailed introduction to the method for preparing a groove structure in a discrete device and the discrete device provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for preparing a trench structure in a discrete device, characterized in that: include: A device preform is provided; the device preform comprises a substrate, and a patterned mask layer located on the front side of the substrate, the front side of the substrate is provided with a groove structure formed by using the patterned mask layer and forming a depression toward the back side of the substrate, and the patterned mask layer comprises only a film layer of the same material; Polishing the front surface of the device preform by using a chemical mechanical polishing process until the patterned mask layer and a portion of the thickness of the substrate are removed to obtain a first device to be processed; The front side of the substrate in the first device to be processed is polished to form a damaged layer of partial thickness; Prepare a reaction layer on the front side of the first device to be processed, so that the reaction layer reacts with the damaged layer in the first device to be processed to generate a reaction layer to be removed, thereby obtaining a second device to be processed; The reaction layer to be removed in the second device to be processed is removed to complete the preparation of the trench structure in the discrete device.

2. The method for preparing a trench structure in a discrete device according to claim 1, characterized in that: The groove structure arranged on the front surface of the substrate is a shielding grid groove structure; The shielding gate groove structure is provided with a functional layer and an isolation protection layer located on the front side of the functional layer and prepared by a high-density plasma chemical vapor deposition process.

3. The method for preparing a trench structure in a discrete device according to claim 2, characterized in that: The method comprises polishing the front side of the device preform by using a chemical mechanical polishing process until the patterned mask layer and a part of the thickness of the substrate are removed to obtain a first device to be processed, comprising: The front side of the device preform is polished by using a chemical mechanical polishing process until the isolation protection layer and the patterned mask layer on the front side of the substrate are removed, and a portion of the thickness of the substrate is removed to obtain the first device to be processed.

4. The method for preparing a trench structure in a discrete device according to claim 3, characterized in that: The grinding liquid in the chemical mechanical polishing process is a grinding liquid containing cerium oxide slurry.

5. The method for preparing a trench structure in a discrete device according to claim 3, characterized in that: After obtaining the first device to be processed, the method further includes: A wet etching process is used to remove a portion of the thickness of the isolation protection layer in the shielding gate trench structure.

6. The method for preparing a trench structure in a discrete device according to claim 1, characterized in that: Preparing a reaction layer on the front side of the first device to be processed so that the reaction layer reacts with the damaged layer in the first device to be processed to generate a reaction layer to be removed, thereby obtaining a second device to be processed, comprising: A sacrificial oxide layer is prepared on the front surface of the first device to be processed by a deposition process, so that the sacrificial oxide layer reacts with the damaged layer in the first device to be processed to generate an oxide layer to be removed, thereby obtaining the second device to be processed.

7. The method for preparing a trench structure in a discrete device according to claim 6, characterized in that: The substrate is a silicon substrate; The oxide layer to be removed is a damaged layer formed in the silicon substrate, and is a silicon oxide layer to be removed generated by reacting with the sacrificial oxide layer.

8. The method for preparing a trench structure in a discrete device according to claim 1, characterized in that: The providing of a device preform comprises: Providing an initial substrate, and preparing a mask layer on the front side of the initial substrate; the mask layer only includes a film layer of the same material; Etching the area of ​​the mask layer corresponding to the preparation of the groove structure until the front surface of the initial substrate is exposed to obtain the patterned mask layer; The initial substrate is etched along the front surface of the initial substrate exposed by the patterned mask layer toward the reverse surface of the initial substrate to form the groove structure as the device preform.

9. The method for preparing a trench structure in a discrete device according to claim 1, characterized in that: The patterned mask layer includes only one oxide film layer.

10. A discrete device, characterized in that: Prepared by the method for preparing a trench structure in a discrete device according to any one of claims 1 to 9, comprising the substrate; The front surface of the substrate is provided with the groove structure recessed toward the back surface of the substrate.

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