Method for manufacturing side wall of storage unit
By using stress proximity etching process to reduce the lateral depth of the depression in the L-shaped side wall structure of the memory cell, and filling the depression by depositing the dielectric layer, the hollow problem caused by etching of the metal silicide barrier layer is solved, and the reliability of the device is improved.
Patent Information
- Application Number
- CN202510216814.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-25
- Publication Date
- 2025-05-16
AI Technical Summary
In the L-shaped side wall structure of the memory cell, the etching of the metal silicide barrier layer will cause the side digging of the underlying silicon oxide layer to form depressions, and the subsequent filling process will be difficult to close the depressions, resulting in the formation of voids, affecting the reliability of the device.
After the metal silicide production is completed, the exposed silicon nitride layer is etched by stress-closing the lateral depth of the depression, and the depression is filled by a deposition dielectric layer to avoid the formation of voids.
By reducing the lateral digging depth of the depression, the morphology of the silicon nitride layer is improved, the effect of filling the dielectric layer is improved, the formation of voids is avoided, and the reliability of the device is enhanced.
Smart Images
Figure CN120015622A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of semiconductor integrated circuit manufacturing, and in particular to a method for manufacturing a storage unit sidewall. Background Art
[0002] For the storage unit, an L-shaped sidewall structure is formed on its outer sidewall, and the L-shaped sidewall structure includes a bottom silicon oxide layer, a silicon nitride layer, and an upper silicon oxide layer stacked in sequence from bottom to top. The outer side of the L-shaped sidewall structure is covered with a metal silicide barrier layer. When the metal silicide barrier layer is etched, the bottom silicon oxide layer of the L-shaped sidewall structure will be undercut to form a depression. The subsequent metal silicide deposition process will not only make it difficult to fill the depression, but also cause the depression to be sealed to form a void. As a result, when the contact hole is subsequently made, the metal filled in is easy to diffuse along the hole to form a bridge problem, which is not conducive to the reliability of the device. Summary of the invention
[0003] The present application provides a method for manufacturing a storage unit side wall, which can solve the problem of a cavity being formed at the bottom of an L-shaped side wall structure in the related art.
[0004] In order to solve the technical problem in the background technology, the present application provides a method for manufacturing a storage unit sidewall, and the method for manufacturing a storage unit sidewall comprises the following steps: A semiconductor substrate is provided, on which a plurality of memory cells are formed, and an L-shaped sidewall structure is formed on the sidewall of the memory cell, wherein the L-shaped sidewall structure comprises a bottom silicon oxide layer, a silicon nitride layer and an upper silicon oxide layer stacked in sequence from bottom to top; Depositing a metal silicide barrier layer, wherein the metal silicide barrier layer covers the surface of the L-shaped sidewall structure; Etching the metal silicide barrier layer to cause a side cut to form a depression at the edge of the bottom silicon oxide layer of the L-shaped sidewall structure; After the metal silicide is manufactured, the exposed silicon nitride layer is etched by a stress proximity etching process to reduce the side-cut depth of the recess; A dielectric layer is deposited, and the dielectric layer fills the shrunken recess.
[0005] Optionally, the step of etching the metal silicide barrier layer to cause a recess at the edge of the bottom silicon oxide layer of the L-shaped sidewall structure includes: Defining a metal silicide barrier layer etching pattern by a photolithography process; Dry-etching the metal silicide barrier layer based on the metal silicide barrier layer etching pattern to remove the metal silicide barrier layer exposed from the metal silicide barrier layer etching pattern; After removing the metal silicide barrier layer etching pattern, further removing the metal silicide barrier layer by wet etching process; The edge of the bottom silicon oxide layer of the L-shaped sidewall structure is hollowed out to form a depression.
[0006] Optionally, after the metal silicide is manufactured, the step of etching the exposed silicon nitride layer by a stress proximity etching process to reduce the side-cut depth of the recess includes: forming a metal silicide layer on the exposed silicon surface by a metal silicide process; The exposed silicon nitride layer is etched by a stress proximity etching process, so that the bottom of the L-shaped sidewall structure and the silicon nitride layer beyond the recessed position are laterally shortened by the stress proximity etching process, thereby reducing the side excavation depth of the recess.
[0007] Optionally, the step of etching the exposed silicon nitride layer by a stress proximity etching process so that the bottom of the L-shaped sidewall structure, the silicon nitride layer beyond the recessed position is thinned by the stress proximity etching process, and the side excavation depth of the recess is reduced includes: Under a pressure environment of 10mtorr to 30mtorr, the exposed silicon nitride layer is etched by a stress proximity etching process, so that the bottom of the L-shaped sidewall structure and the silicon nitride layer beyond the recessed position are laterally shortened by the stress proximity etching process, thereby reducing the side excavation depth of the recess.
[0008] Optionally, the step of etching the exposed silicon nitride layer by a stress proximity etching process so that the bottom of the L-shaped sidewall structure, the silicon nitride layer beyond the recessed position is thinned by the stress proximity etching process, and the side excavation depth of the recess is reduced includes: In an atmosphere including polymer gas and oxygen, the exposed silicon nitride layer is etched by a stress proximity etching process, so that the bottom of the L-shaped sidewall structure and the silicon nitride layer beyond the recessed position are laterally shortened by the stress proximity etching process, thereby reducing the side excavation depth of the recess.
[0009] Optionally, the step of depositing a dielectric layer, wherein the dielectric layer fills the shrunk recess, comprises: The deposited material is a contact hole etching stop layer, and the contact hole etching stop layer fills the recess completely; An isolation dielectric layer is deposited on the contact hole etching stop layer.
[0010] Optionally, the contact hole etch stop layer includes silicon oxynitride and silicon oxide.
[0011] Optionally, the isolation dielectric layer is made of silicon oxide.
[0012] The technical solution of the present application includes at least the following advantages: after the metal silicide is produced, the present application etches the exposed silicon nitride layer through a stress proximity etching process, thereby reducing the side-excavation depth of the recess and modifying the morphology of the corner of the silicon nitride layer, improving the surface morphology of the space filled by the dielectric layer, facilitating the filling of the dielectric layer and avoiding the formation of voids. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] 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.
[0014] Figure 1 A flow chart of a method for manufacturing a storage unit sidewall provided by an embodiment of the present application is shown; Figure 2 A schematic diagram of a cross-sectional structure of the device after step S1 is completed is shown; Figure 3 A schematic diagram of the cross-sectional structure of the device after step S2 is completed is shown; Figure 4 A schematic diagram of the cross-sectional structure of the device after step S3 is completed is shown; Figure 5 FIG. 4 shows a schematic diagram of a cross-sectional structure of the device after step S4 is completed. DETAILED DESCRIPTION
[0015] 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.
[0016] 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.
[0017] 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.
[0018] 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.
[0019] Figure 1 A flow chart of a method for manufacturing a storage unit sidewall provided by an embodiment of the present application is shown, from Figure 1 As can be seen from the figure, the method for manufacturing the storage unit sidewall comprises the following steps: Step S1: providing a semiconductor substrate on which a plurality of spaced-apart memory cells are formed, and an L-shaped sidewall structure is formed on the sidewalls of the memory cells, wherein the L-shaped sidewall structure comprises a bottom silicon oxide layer, a silicon nitride layer and an upper silicon oxide layer stacked in sequence from bottom to top.
[0020] Reference Figure 2 , which shows a schematic diagram of the cross-sectional structure of the device after step S1 is completed. Figure 2 As can be seen in the figure, a plurality of spaced memory cells 110 are formed on the semiconductor substrate 100. An L-shaped sidewall structure 120 is formed on the sidewall of the memory cell 110. The L-shaped sidewall structure 120 includes a bottom silicon oxide layer 121, a silicon nitride layer 122 and an upper silicon oxide layer 123 stacked from bottom to top.
[0021] Step S2: depositing a metal silicide barrier layer, wherein the metal silicide barrier layer covers the surface of the L-shaped sidewall structure.
[0022] For example, a metal silicide barrier layer may be blanket deposited to cover the surface of the L-shaped spacer structure, the upper surface of the memory cell, and the spacer surface between two adjacent memory cells.
[0023] Figure 3 The schematic diagram of the cross-sectional structure of the device after step S2 is completed is shown. Figure 3 As can be seen in FIG. 1 , the metal silicide barrier layer 200 covers the surface of the L-shaped spacer structure 120 , the upper surface of the memory cell 110 , and the spacer surface between two adjacent memory cells 110 .
[0024] Step S3: etching the metal silicide barrier layer to cause undercutting of the edge of the bottom silicon oxide layer of the L-shaped sidewall structure to form a depression.
[0025] Figure 4 The schematic diagram of the cross-sectional structure of the device after step S3 is completed is shown. Figure 4 It can be seen that after the metal silicide barrier layer is etched, the metal silicide barrier layer 200 located on the upper surface of the memory cell 110 and the spacer surface between two adjacent memory cells 110 is removed by etching, and the remaining metal silicide barrier layer 200 covers the side surface of the L-shaped sidewall structure 120. The metal silicide barrier layer 200 at the corner is also removed by etching. The edge of the bottom silicon oxide layer 121 of the L-shaped sidewall structure 120 is undercut to form a recess 300.
[0026] Exemplarily, the above step S3 may be implemented according to the following steps: Step S31: defining a metal silicide barrier layer etching pattern by a photolithography process.
[0027] The metal silicide barrier layer on the upper surface of the memory cell and the spacer surface between two adjacent memory cells is exposed from the metal silicide barrier layer etching pattern.
[0028] Step S32: dry-etching the metal silicide barrier layer based on the metal silicide barrier layer etching pattern to remove the metal silicide barrier layer exposed from the metal silicide barrier layer etching pattern.
[0029] Exemplarily, the metal silicide barrier layer on the upper surface of the memory cell and the spacer surface between two adjacent memory cells is removed by etching.
[0030] Step S33: After removing the metal silicide barrier layer etching pattern, further remove the metal silicide barrier layer by wet etching process.
[0031] After the etching step is completed, the metal silicide barrier layer is removed by etching, and the wet etching solution accumulates at the bottom of the L-shaped sidewall structure, thereby causing undercutting of the edge of the bottom silicon oxide layer of the L-shaped sidewall structure to form a depression.
[0032] Step S4: After the metal silicide is manufactured, the exposed silicon nitride layer is etched by a stress proximity etching process to reduce the side-cut depth of the recess.
[0033] Reference Figure 5 , which shows a schematic diagram of the cross-sectional structure of the device after step S4 is completed. Figure 5It can be seen that the fabricated metal silicide 400 covers the storage unit 110. After the metal silicide 400 is deposited, a stress proximity etching process is performed. The stress proximity etching process has high selectivity for the silicon nitride layer, so that the exposed silicon nitride layer can be etched, especially the bottom of the silicon nitride layer 122 of the L-shaped sidewall structure 120. The silicon nitride layer 122 beyond the position of the recess 300 is etched and thinned by the stress proximity etching process, so that the side excavation depth of the recess can be reduced, paving the way for the subsequently deposited dielectric layer to fill the recess, and avoiding the problem of voids in the recess.
[0034] For example, the exposed silicon nitride layer can be etched by a stress proximity etching process under a pressure environment of 10 mtorr to 30 mtorr in an atmosphere environment including polymer gas and oxygen, so that the bottom of the L-shaped sidewall structure, the silicon nitride layer beyond the recessed position is etched laterally by the stress proximity etching process, and the side excavation depth of the recess is reduced. The polymer gas includes fluorine-containing methane gas, such as CH3F gas and CH2F2 gas.
[0035] Step S5: depositing a dielectric layer, wherein the dielectric layer fills the shrunken recess.
[0036] For example, a contact hole etch stop layer may be deposited first, the contact hole etch stop layer comprising silicon oxynitride and silicon oxide, and the contact hole etch stop layer covers the Figure 5 The device surface shown in Figure 5 The side-excavation depth of the recess shown is reduced, so that the deposited contact hole etching stop layer can fill the recess completely, thereby preventing the recess from forming a cavity. Subsequently, an isolation dielectric layer is deposited on the contact hole etching stop layer. The material of the isolation dielectric layer is silicon oxide.
[0037] After the metal silicide is produced, the present application etches the exposed silicon nitride layer through a stress proximity etching process, thereby reducing the side-excavation depth of the recess and modifying the morphology of the corner of the silicon nitride layer, improving the surface morphology of the dielectric layer filling space, facilitating the filling of the dielectric layer and avoiding the formation of voids.
[0038] 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 from them are still within the scope of protection created by this application.
Claims
1. A method for manufacturing a storage unit side wall, characterized in that: The manufacturing method of the storage unit side wall comprises the following steps: A semiconductor substrate is provided, on which a plurality of memory cells are formed, and an L-shaped sidewall structure is formed on the sidewall of the memory cell, wherein the L-shaped sidewall structure comprises a bottom silicon oxide layer, a silicon nitride layer and an upper silicon oxide layer stacked in sequence from bottom to top; Depositing a metal silicide barrier layer, wherein the metal silicide barrier layer covers the surface of the L-shaped sidewall structure; Etching the metal silicide barrier layer to cause a side cut to form a depression at the edge of the bottom silicon oxide layer of the L-shaped sidewall structure; After the metal silicide is manufactured, the exposed silicon nitride layer is etched by a stress proximity etching process to reduce the side-cut depth of the recess; A dielectric layer is deposited, and the dielectric layer fills the shrunken recess.
2. The method for manufacturing a storage unit sidewall as claimed in claim 1, characterized in that: The step of etching the metal silicide barrier layer to cause a side cut to form a depression at the edge of the bottom silicon oxide layer of the L-shaped sidewall structure comprises: Defining a metal silicide barrier layer etching pattern by a photolithography process; Dry-etching the metal silicide barrier layer based on the metal silicide barrier layer etching pattern to remove the metal silicide barrier layer exposed from the metal silicide barrier layer etching pattern; After removing the metal silicide barrier layer etching pattern, further removing the metal silicide barrier layer by wet etching process; The edge of the bottom silicon oxide layer of the L-shaped sidewall structure is hollowed out to form a depression.
3. The method for manufacturing a storage unit sidewall as claimed in claim 1, characterized in that: The step of etching the exposed silicon nitride layer through a stress proximity etching process after the metal silicide is made to reduce the side-digging depth of the recess comprises: forming a metal silicide layer on the exposed silicon surface by a metal silicide process; The exposed silicon nitride layer is etched by a stress proximity etching process, so that the bottom of the L-shaped sidewall structure and the silicon nitride layer beyond the recessed position are laterally shortened by the stress proximity etching process, thereby reducing the side excavation depth of the recess.
4. The method for manufacturing a storage unit sidewall as claimed in claim 3, characterized in that: The step of etching the exposed silicon nitride layer by the stress proximity etching process so that the silicon nitride layer at the bottom of the L-shaped sidewall structure beyond the recessed position is etched and thinned by the stress proximity etching process to reduce the side digging depth of the recess comprises: Under a pressure environment of 10mtorr to 30mtorr, the exposed silicon nitride layer is etched by a stress proximity etching process, so that the bottom of the L-shaped sidewall structure and the silicon nitride layer beyond the recessed position are laterally shortened by the stress proximity etching process, thereby reducing the side excavation depth of the recess.
5. The method for manufacturing a storage unit sidewall as claimed in claim 3, characterized in that: The step of etching the exposed silicon nitride layer by the stress proximity etching process so that the silicon nitride layer at the bottom of the L-shaped sidewall structure beyond the recessed position is etched and thinned by the stress proximity etching process to reduce the side digging depth of the recess comprises: In an atmosphere including polymer gas and oxygen, the exposed silicon nitride layer is etched by a stress proximity etching process, so that the bottom of the L-shaped sidewall structure and the silicon nitride layer beyond the recessed position are laterally shortened by the stress proximity etching process, thereby reducing the side excavation depth of the recess.
6. The method for manufacturing a storage unit sidewall as claimed in claim 1, characterized in that: The step of depositing a dielectric layer, wherein the dielectric layer fills the shrunken recess, comprises: The deposited material is a contact hole etching stop layer, and the contact hole etching stop layer fills the recess completely; An isolation dielectric layer is deposited on the contact hole etching stop layer.
7. The method for manufacturing a storage unit sidewall as claimed in claim 6, characterized in that: The contact hole etching stop layer includes silicon oxynitride and silicon oxide.
8. The method for manufacturing a storage unit sidewall as claimed in claim 6, characterized in that: The material of the isolation dielectric layer is silicon oxide.