Method for improving adhesive layer residue problem

Abstract

The invention discloses a method for improving a bonding layer residue problem, which comprises the following steps of: providing a substrate on which a silicon nitride layer and an enhanced plasma oxide layer are sequentially formed from bottom to top; through photoetching and etching processes, a through hole zero layer is formed on the edge of the enhanced plasma oxide layer, and the through hole zero layer penetrates through part of the silicon nitride layer; depositing a bonding layer, wherein the bonding layer covers the enhanced plasma oxide layer and the exposed silicon nitride layer; a metal layer is formed on the bonding layer in a crystal edge removing and film forming mode; removing the bonding layer which is not covered by the metal layer on the edge by adopting a wet etching process; and performing a chemical mechanical polishing process until the thickness of the residual enhanced plasma oxide layer reaches the target thickness. By means of the scheme, the problem that in the related technology, the bonding layer on the edge portion of the wafer falls off in the chemical mechanical polishing engineering, and the wafer performance is affected can be solved.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor manufacturing, and in particular to a method for improving the problem of adhesive layer residue. Background Art

[0002] like Figure 1 As shown, it is a schematic diagram of a wafer in the manufacturing process of a semiconductor device, which includes a substrate, a silicon nitride layer, an enhanced plasma oxide layer, an adhesive layer and a metal layer formed on the substrate, the adhesive layer covers the enhanced plasma oxide layer and the exposed silicon nitride layer, and the metal layer covers the middle part of the adhesive layer, so that the edge of the adhesive layer is exposed. Among them, for the crystal edge part, due to multiple SOC edge washing processes in the pre-process, its surface will be uneven, resulting in poor roughness and poor adhesion to the adhesive layer. In the subsequent chemical mechanical polishing process of the metal layer, the adhesive layer at the above-mentioned position will fall off, forming a thin sheet of adhesive residue and adhering to the wafer surface, which affects the performance of the wafer. At the same time, in the subsequent KLA test, CP test and HVS test process, the thin sheet of adhesive residue is difficult to be detected, which seriously affects the reliability of the product. Summary of the invention

[0003] The present application provides a method for improving the problem of adhesive layer residue, which can solve the problem of poor product reliability caused by adhesive layer residue in the related art.

[0004] The present application embodiment provides a method for improving the problem of adhesive layer residue, comprising: Providing a substrate, on which a silicon nitride layer and an enhanced plasma oxidation layer are sequentially formed from bottom to top; By means of photolithography and etching processes, a through hole zero layer is formed at the edge of the enhanced plasma oxide layer, wherein the through hole zero layer penetrates part of the silicon nitride layer; Depositing an adhesion layer, the adhesion layer covering the enhanced plasma oxidation layer and the exposed silicon nitride layer; Forming a metal layer on the adhesive layer by adopting a crystal edge removal film forming method; Using a wet etching process to remove the adhesive layer at the edge that is not covered by the metal layer; The chemical mechanical polishing process is performed until the thickness of the remaining enhanced plasma oxidation layer reaches a target thickness.

[0005] In some embodiments, the step of forming a through-hole zero layer at the edge of the enhanced plasma oxide layer by photolithography and etching processes includes: Using photolithography and dry etching processes, etching the enhanced plasma oxidation layer in a preset area to form a through-hole zero layer, wherein the preset area is located at the edge of the enhanced plasma oxidation layer; The exposed silicon nitride layer is etched by a dry etching process.

[0006] In some embodiments, the adhesion layer is a Ti / TiN layer.

[0007] In some embodiments, forming a metal layer on the adhesive layer comprises: The metal layer is formed by depositing tungsten on the adhesion layer by a chemical vapor deposition process.

[0008] In some embodiments, in the step of removing the adhesive layer at the edge that is not covered by the metal layer by a wet etching process, the cleaning liquid used is a mixed solution of hydrogen peroxide and ammonia.

[0009] The technical solution of this application has at least the following advantages: 1. After depositing the metal layer, the adhesive layer at the edge of the wafer that is not covered by the metal layer is removed by a wet etching process, thereby avoiding the adhesion layer at the edge falling off and affecting the wafer performance during the subsequent chemical mechanical polishing process, thereby improving the reliability of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0011] Figure 1 It is a schematic diagram of a wafer of a semiconductor device in the manufacturing process in the prior art; Figure 2 is a flow chart of a method for improving the adhesive layer residue problem provided by an exemplary embodiment of the present application; Figure 3~Figure 8 is a schematic diagram of a device structure during implementation of a method for improving the adhesive layer residue problem provided by an exemplary embodiment of the present application; Fig. 9 It is a statistical chart provided by an exemplary embodiment of the present application for reflecting the number of abnormal occurrences of sheet-like adhesive residues before and after using the present method.

[0012] Explanation of the reference numerals: 1. substrate; 2. silicon nitride layer; 3. enhanced plasma oxidation layer; 4. through-hole zero layer; 5. adhesion layer; 6. metal layer. DETAILED DESCRIPTION

[0013] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0014] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0015] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0016] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0017] The present application provides a method for improving the problem of adhesive layer residue, referring to Figure 2 , the method includes the following contents: S1: providing a substrate, on which a silicon nitride layer and an enhanced plasma oxidation layer are sequentially formed from bottom to top.

[0018] For example, refer to Figure 3 A substrate 1 is provided, on which a silicon nitride layer 2 and an enhanced plasma oxidation layer 3 are sequentially formed from bottom to top.

[0019] S2: A through hole zero layer is formed at the edge of the enhanced plasma oxide layer through a photolithography and etching process, and the through hole zero layer penetrates a portion of the silicon nitride layer.

[0020] For example, refer to Figure 4 Through photolithography and etching processes, a through hole zero layer 4 is formed at the edge of the enhanced plasma oxidation layer 3, and the through hole zero layer 4 penetrates a portion of the silicon nitride layer 2.

[0021] Further, the processing process of this step can be as follows: first, a photoresist layer of a predetermined pattern is coated on the enhanced plasma oxidation layer 3, and the photoresist layer blocks the enhanced plasma oxidation layer 3 that does not need to be etched, that is, the enhanced plasma oxidation layer 3 at the edge, for example, the enhanced plasma oxidation layer 3 within a horizontal distance of 0.7 mm from the edge of the wafer. Then, the exposed enhanced plasma oxidation layer 3 is etched by a dry etching process using the photoresist layer as a mask to form a through-hole zero layer 4. Then, along the through-hole zero layer 4 formed above, the exposed silicon nitride layer 2 below is dry-etched to a predetermined depth.

[0022] S3: depositing an adhesion layer, wherein the adhesion layer covers the enhanced plasma oxidation layer and the exposed silicon nitride layer.

[0023] For example, refer to Figure 5 , an adhesion layer 5 is deposited on the enhanced plasma oxidation layer 3 and the exposed silicon nitride layer 2.

[0024] Furthermore, the bonding layer 5 is a Ti / TiN layer. When forming the Ti / TiN layer, Ti is deposited by a physical vapor deposition process, and TiN is deposited by a chemical vapor deposition process, wherein the thickness of the deposited Ti can be 25 angstroms, and the thickness of the deposited TiN can be 20 angstroms.

[0025] S4: forming a metal layer on the adhesive layer by adopting a crystal edge removal film forming method.

[0026] For example, refer to Figure 6 A metal layer 6 is formed on the adhesive layer 5 by adopting a crystal edge removal film forming method.

[0027] Furthermore, tungsten can be deposited on the bonding layer 5 by a chemical vapor deposition process to form a metal layer 6. At the same time, during the deposition of tungsten, the deposition machine will cover a sealing ring at a fixed distance from the edge of the wafer. For example, the fixed distance can be 2 mm, thereby shielding the portion of the wafer within 2 mm of the edge of the wafer. Due to the presence of the sealing ring, when tungsten is deposited, the precursor of the reaction cannot pass through the sealing ring to the bottom. Therefore, the portion of the wafer within 2 mm of the edge of the wafer will not be deposited with the metal layer 6, that is, the metal layer 6 is formed by using the method of edge removal of the edge of the wafer.

[0028] S5: Using a wet etching process, remove the adhesive layer at the edge that is not covered by the metal layer.

[0029] For example, refer to Figure 7 , a wet etching process is used to remove the edge of the adhesive layer 5 that is not covered by the metal layer 6.

[0030] Furthermore, in the wet process, SC1 solution (a mixture of hydrogen peroxide and ammonia) is used as a cleaning solution to remove the bonding layer 5 not covered by the metal layer 6, that is, the Ti / TiN layer, wherein the ratio of hydrogen peroxide to ammonia in the SC1 solution can be 10:1. Specifically in the wet etching machine, the position of the nozzle can be set so that the cleaning solution will be sprayed onto the bonding layer 5 at the edge of the wafer that is not covered by the metal layer 6, without damaging the bonding layer 5 under the metal layer 6.

[0031] S6: performing a chemical mechanical polishing process until the thickness of the remaining enhanced plasma oxidation layer reaches a target thickness.

[0032] For example, refer to Figure 8 , a chemical mechanical polishing process is performed to sequentially remove the metal layer 6, the bonding layer 5 and the top enhanced plasma oxidation layer 3 until the remaining enhanced plasma oxidation layer 3 reaches a target thickness. The target thickness can be specifically set according to the device requirements, and this application does not impose any specific restrictions.

[0033] Reference Fig. 9 , Fig. 9 This is a statistical graph of the number of abnormal occurrences of sheet-like adhesive residues (vertical axis) versus date (horizontal axis), wherein the left side of the dotted line is before using the method described in this application, and the right side of the dotted line is after using the method described in this application. It can be found that the number of abnormal occurrences of sheet-like adhesive residues on the right side of the dotted line approaches 0, and the problem of abnormal sheet-like adhesive residues has been significantly improved.

[0034] The method for improving the residual adhesive layer problem provided in the embodiment of the present application is to remove the adhesive layer 5 at the edge of the wafer that is not covered by the metal layer 6 through a wet etching process after depositing the metal layer 6, thereby avoiding the adhesion layer 5 at the edge part from falling off and affecting the wafer performance during the subsequent chemical mechanical polishing process, thereby improving the reliability of the product.

[0035] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection created by this application.

Claims

1. A method for improving the problem of adhesive layer residue, characterized in that: include: Providing a substrate, on which a silicon nitride layer and an enhanced plasma oxidation layer are sequentially formed from bottom to top; By means of photolithography and etching processes, a through hole zero layer is formed at the edge of the enhanced plasma oxide layer, wherein the through hole zero layer penetrates part of the silicon nitride layer; Depositing an adhesion layer, the adhesion layer covering the enhanced plasma oxidation layer and the exposed silicon nitride layer; Forming a metal layer on the adhesive layer by adopting a crystal edge removal film forming method; Using a wet etching process to remove the adhesive layer at the edge that is not covered by the metal layer; The chemical mechanical polishing process is performed until the thickness of the remaining enhanced plasma oxidation layer reaches a target thickness.

2. The method according to claim 1, characterized in that: The step of forming a through hole zero layer at the edge of the enhanced plasma oxide layer by photolithography and etching processes comprises: Using photolithography and dry etching processes, etching the enhanced plasma oxidation layer in a preset area to form a through-hole zero layer, wherein the preset area is located at the edge of the enhanced plasma oxidation layer; The exposed silicon nitride layer is etched by a dry etching process.

3. The method according to claim 1, characterized in that The bonding layer is a Ti / TiN layer.

4. The method according to claim 1, characterized in that: The step of forming a metal layer on the adhesive layer comprises: The metal layer is formed by depositing tungsten on the adhesion layer by a chemical vapor deposition process.

5. The method according to claim 1, characterized in that In the step of removing the adhesive layer at the edge that is not covered by the metal layer by a wet etching process, the cleaning liquid used is a mixed solution of hydrogen peroxide and ammonia.

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