Manufacturing method of copper interconnection structure
Through the method of ammonia plasma bombardment and nitrogen radical reaction, stress in the copper interconnection layer is released in stages, solving the problem of copper penetration caused by hilly protrusions in the copper interconnection process in the prior art, and improving the reliability of the copper interconnection layer.
Patent Information
- Application Number
- CN202510098157.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-22
- Publication Date
- 2025-06-13
AI Technical Summary
In the existing copper interconnection process, hay-like protrusions often occur after deposition of nitrogen DC films, resulting in copper penetration and increasing the risk of current breakdown.
The copper oxide surface layer is bombarded by ammonia plasma, and the stress between the copper grains in the copper interconnection layer is released into two stages, converted into reduced copper, and a copper nitride layer is formed by reacting nitrogen radicals with reduced copper. Finally, these layers are removed by chemical mechanical grinding to form a carbon doped silicon nitride layer.
The formation of mound-like protrusions during the deposition of carbon doped silicon nitride layer is effectively avoided, the risk of copper penetration is reduced, and the reliability of the copper interconnection layer is improved.
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Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor integrated circuit manufacturing technology, and specifically relates to a manufacturing method of a copper interconnect structure. Background Art
[0002] Carbon-doped silicon nitride (SiNDC) is widely used in the back-end copper interconnect process due to its good etching selectivity, good copper adhesion, good copper diffusion barrier ability, and relatively low dielectric constant.
[0003] For the existing copper interconnect process, a large number of hillocks are generated after the deposition of the SiNDC film. These hillocks are formed by the regrowth of copper or copper oxide grains in the high-temperature environment during the deposition of the SiNDC film, and the hillocks often form at the grain boundaries of copper.
[0004] Due to the relatively weak penetration phenomenon of copper hillocks in the corner area, and as the process nodes gradually move downwards, the distance between copper wires becomes shorter and shorter, resulting in an increasing risk of current breakdown caused by copper penetration. Summary of the Invention
[0005] This application provides a manufacturing method of a copper interconnect structure, which can solve the problem of hillock formation in related technologies.
[0006] To solve the technical problems in the background art, this application provides a manufacturing method of a copper interconnect structure. The manufacturing method of the copper interconnect structure includes the following steps: Manufacture and form a copper interconnect layer, the surface of the copper interconnect layer has a copper oxide surface layer; Bombard the copper oxide surface layer with ammonia plasma for a first period to release the stress between copper grains in the copper interconnect layer, so that the ammonia plasma converts the copper oxide surface layer into reduced copper during the first period; Continue to introduce ammonia plasma in a second period. During the second period, the ammonia plasma dissociates to form nitrogen radicals, and the nitrogen radicals react with the reduced copper to form a copper nitride layer covering the surface of the copper interconnect layer to release the stress between copper grains in the copper interconnect layer; Remove the copper nitride layer by chemical mechanical polishing process; Deposit a carbon-doped silicon nitride layer on the surface of the chemical mechanical polishing.
[0007] Optionally, the step of bombarding the copper oxide surface layer with ammonia plasma for a first period to release the stress between copper grains in the copper interconnect layer, so that the ammonia plasma converts the copper oxide surface layer into reduced copper during the first period, includes: With a bombardment direction at an angle of 0° to 45° with respect to the vertical direction, bombard the surface layer of the copper oxide with ammonia plasma in the first period to release the stress between the copper grains in the copper interconnect layer, so that the ammonia plasma converts the surface layer of the copper oxide into reduced copper in the first period.
[0008] Optionally, the step of releasing the stress between the copper grains in the copper interconnect layer by bombarding the surface layer of the copper oxide with ammonia plasma in the first period, so that the ammonia plasma converts the surface layer of the copper oxide into reduced copper in the first period, includes: Under an environment of a radio frequency power of 500W to 600W, bombard the surface layer of the copper oxide with ammonia plasma having a flow rate of 1000sccm to 1500sccm in the first period to release the stress between the copper grains in the copper interconnect layer, so that the ammonia plasma converts the surface layer of the copper oxide into reduced copper in the first period.
[0009] Optionally, the step of continuously introducing ammonia plasma in the second period, in which the ammonia plasma dissociates to form nitrogen radicals in the second period, and the nitrogen radicals react with the reduced copper to form a copper nitride layer covering the surface of the copper interconnect layer to release the stress between the copper grains in the copper interconnect layer, includes: With a bombardment direction at an angle of 0° to 45° with respect to the vertical direction, continue to bombard the reduced copper with ammonia plasma in the second period. In the second period, the ammonia plasma dissociates to form nitrogen radicals, and the nitrogen radicals react with the reduced copper to form a copper nitride layer covering the surface of the copper interconnect layer to release the stress between the copper grains in the copper interconnect layer.
[0010] Optionally, the step of continuously introducing ammonia plasma in the second period, in which the ammonia plasma dissociates to form nitrogen radicals in the second period, and the nitrogen radicals react with the reduced copper to form a copper nitride layer covering the surface of the copper interconnect layer to release the stress between the copper grains in the copper interconnect layer, includes: Under an environment of a radio frequency power of 500W to 600W, continue to bombard the surface layer of the copper oxide with ammonia plasma having a flow rate of 1000sccm to 1500sccm in the second period. In the second period, the ammonia plasma dissociates to form nitrogen radicals, and the nitrogen radicals react with the reduced copper to form a copper nitride layer covering the surface of the copper interconnect layer to release the stress between the copper grains in the copper interconnect layer.
[0011] Optionally, continue to introduce ammonia plasma in the second period, in which the ammonia plasma dissociates to form nitrogen radicals, and the nitrogen radicals react with reduced copper to form a copper nitride layer covering the surface of the copper interconnect layer to release the stress between copper grains in the copper interconnect layer. The thickness of the copper nitride layer in this step is 15 Å to 25 Å.
[0012] Optionally, the step of removing the copper nitride layer by chemical mechanical polishing process includes: Removing the copper nitride layer by chemical mechanical polishing process; Removing the copper interconnect surface layer with a thickness of 25 Å to 35 Å in the copper interconnect layer by chemical mechanical polishing process.
[0013] The technical solution of this application has at least the following advantages: In this application, ammonia plasma in the first period is introduced first to consume copper oxide and release the stress between copper grains in the copper interconnect layer, and then ammonia plasma in the second period is continuously introduced to continue releasing the stress between copper grains in the copper interconnect layer, so that the stress between copper grains in the copper interconnect layer changes from a high-stress state to a low-stress state, thereby avoiding the re-growth of hillock protrusions at the grain boundaries between grains during the subsequent deposition of the carbon-doped silicon nitride layer. At the same time, dividing the stress release process between copper grains in the copper interconnect layer into two stages can avoid the problem of damage to the copper interconnect layer caused by sudden stress release and improve the reliability of the copper interconnect layer. Description of the Drawings
[0014] In order to more clearly illustrate the specific embodiments of this application or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0015] Figure 1 Shows a schematic structural diagram of forming hillock protrusions in the related art; Figure 2 Shows a flowchart of a manufacturing method of a copper interconnect structure provided by an embodiment of this application; Figure 3 Shows a schematic cross-sectional structure diagram of the copper interconnect structure when step S2 is carried out; Figure 4 Shows a schematic cross-sectional structure diagram of the copper interconnect structure after step S3 is completed. Detailed Embodiments
[0016] The following will clearly and completely describe the technical solutions in the present application in conjunction with the accompanying drawings. Apparently, the described embodiments are part of the embodiments of the present application, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts fall within the scope of protection of the present application.
[0017] In the description of the present application, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is 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 should not be construed as a limitation to the present application. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.
[0018] In the description of the present 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 directly connected, or indirectly connected through an intermediate medium, and can also be the communication inside two elements. It can be a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.
[0019] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.
[0020] Figure 1 The structural schematic diagram of forming a mound-shaped protrusion in the related art is shown. From Figure 1 In the shown example, the copper includes crystal grains GRAIN1, GRAIN2, and GRAIN3. The grain boundaries between crystal grains GRAIN1, GRAIN2, and GRAIN3 include AB grain boundary, BC grain boundary, and BD grain boundary. Mound-shaped protrusions as shown are generated at the AB grain boundary, BC grain boundary, and BD grain boundary due to relatively large stress. The corner area of the mound-shaped protrusion is relatively weak, and there is a risk of copper penetration. The copper penetration problem causes the distance between copper wires to gradually become shorter as the process node progresses, making the risk of current breakdown increasingly large.
[0021] Figure 2 The flowchart of the manufacturing method of the copper interconnect structure provided by an embodiment of the present application is shown. From Figure 2 It can be seen that the manufacturing method of the copper interconnect structure includes the following steps: Step S1: Fabricate a copper interconnect layer, the surface of which has a copper oxide surface layer.
[0022] Step S2: Bombard the copper oxide surface layer with ammonia plasma for a first period to release the stress between copper grains in the copper interconnect layer, such that the ammonia plasma converts the copper oxide surface layer into reduced copper during the first period.
[0023] Refer to Figure 3 , which shows a schematic cross-sectional structure diagram of the copper interconnect structure when step S2 is carried out. As can be seen from Figure 2 , the surface of the copper interconnect layer 100 has a copper oxide surface layer 200, and the ammonia plasma 300 bombards the copper oxide surface layer 200.
[0024] Before performing step S2, the stress between copper grains in the copper interconnect structure is relatively large. By bombarding the copper oxide surface layer with ammonia plasma for a first period to release the stress between copper grains in the copper interconnect layer, the stress between copper grains in the copper interconnect layer is initially reduced.
[0025] Step S3: Continuously introduce ammonia plasma in a second period. During the second period, the ammonia plasma dissociates to form nitrogen radicals, and the nitrogen radicals react with the reduced copper to form a copper nitride layer covering the surface of the copper interconnect layer to release the stress between copper grains in the copper interconnect layer.
[0026] Refer to Figure 4 , which shows a schematic cross-sectional structure diagram of the copper interconnect structure after step S3 is completed. As can be seen from Figure 3 , the copper oxide 200 on the surface of the copper interconnect layer 100 is converted into a copper nitride layer 400.
[0027] Step S4: Remove the copper nitride layer through a chemical mechanical polishing process.
[0028] Step S5: Deposit a carbon-doped silicon nitride layer on the surface of the chemical mechanical polishing.
[0029] In this embodiment, ammonia plasma in the first period is introduced first to consume copper oxide and release the stress between copper grains in the copper interconnect layer, and then ammonia plasma in the second period is continuously introduced to further release the stress between copper grains in the copper interconnect layer, such that the stress between copper grains in the copper interconnect layer changes from a high-stress state to a low-stress state, thereby avoiding the re-growth of hillock protrusions at the grain boundaries between grains during the subsequent deposition of the carbon-doped silicon nitride layer. At the same time, dividing the stress release process between copper grains in the copper interconnect layer into two stages can avoid the problem of damage to the copper interconnect layer caused by sudden stress release, and improve the reliability of the copper interconnect layer.
[0030] Exemplarily, ammonia plasma in the first period can be bombarded onto the surface layer of copper oxide in a bombardment direction with an angle of 0° to 45° with respect to the vertical direction to release the stress between copper grains in the copper interconnect layer, so that the ammonia plasma converts the surface layer of copper oxide into reduced copper in the first period. It should be noted that by bombarding the surface layer of copper oxide with ammonia plasma in the first period in a bombardment direction with an angle of 0° to 45° with respect to the vertical direction, it is possible to avoid damaging the copper interconnect layer while better releasing the stress between copper grains in the copper interconnect layer.
[0031] Exemplarily, ammonia plasma with a flow rate of 1000 sccm to 1500 sccm in the first period can be bombarded onto the surface layer of copper oxide in an environment with a radio frequency power in the range of 500 W to 600 W to release the stress between copper grains in the copper interconnect layer, so that the ammonia plasma converts the surface layer of copper oxide into reduced copper in the first period. It should be noted that by bombarding the surface layer of copper oxide with ammonia plasma with a flow rate of 1000 sccm in the first period in an environment with a radio frequency power of 560 W, the uniformity of the ammonia plasma bombarding the surface layer of copper oxide can be improved, so that the stress between copper grains in the interconnect layer is released uniformly.
[0032] Exemplarily, ammonia plasma in the second period can be continuously bombarded onto the reduced copper in a bombardment direction with an angle of 0° to 45° with respect to the vertical direction. In the second period, the ammonia plasma dissociates to form nitrogen radicals, and the nitrogen radicals react with the reduced copper to form a copper nitride layer covering the surface of the copper interconnect layer to release the stress between copper grains in the copper interconnect layer. It should be noted that by continuously bombarding the reduced copper with ammonia plasma in the second period in a bombardment direction with an angle of 0° to 45° with respect to the vertical direction, it is possible to make the nitrogen radicals formed by the ammonia plasma react more fully with the reduced copper to form a copper nitride layer, and it is possible to release the stress between copper grains in the copper interconnect layer more fully, so that the stress between copper grains in the copper interconnect layer is in a low-stress state.
[0033] Exemplarily, in an environment with a radio frequency power in the range of 500 W to 600 W, ammonia plasma with a flow rate of 1000 sccm to 1500 sccm can be continuously bombarded onto the surface layer of the copper oxide. During the second period, the ammonia plasma dissociates to form nitrogen radicals, and the nitrogen radicals react with the reduced copper to form a copper nitride layer covering the surface of the copper interconnect layer to release the stress between the copper grains in the copper interconnect layer. It should be noted that in an environment with a radio frequency power of 560 W, continuously bombarding ammonia plasma with a flow rate of 1000 sccm onto the surface layer of the copper oxide can improve the uniformity of the reaction between the nitrogen radicals and the reduced copper, so that the stress between the copper grains in the interconnect layer is evenly released. And during the second period, the radio frequency power of the ammonia plasma bombarding the reduced copper is 560 W. The ammonia plasma with this radio frequency power will not pass through the reduced copper and react with the copper in the copper interconnect layer, thereby avoiding bombarding damage to the grain boundaries between the copper grains in the copper interconnect layer and avoiding the problem of forming mound-like protrusions during the subsequent deposition process of the carbon-doped silicon nitride layer due to the irregular bombarding damage of the copper grain boundaries.
[0034] The thickness of the copper nitride layer formed by the reaction of the nitrogen radicals with the reduced copper and covering the surface of the copper interconnect layer is 15 Å to 25 Å.
[0035] Exemplarily, when removing the copper nitride layer through a chemical mechanical polishing process, the copper nitride layer can be removed first through a chemical mechanical polishing process; then the copper interconnect surface layer with a thickness of 25 Å to 35 Å in the copper interconnect layer can be removed through a chemical mechanical polishing process.
[0036] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill 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 manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.
Claims
1. A method for manufacturing a copper interconnect structure, characterized in that: The method for manufacturing the copper interconnect structure comprises the following steps: Manufacturing and forming a copper interconnection layer, wherein the surface of the copper interconnection layer has a copper oxide surface layer; releasing stress between copper grains in the copper interconnect layer by bombarding the copper oxide surface layer with ammonia plasma during a first period, so that the ammonia plasma converts the copper oxide surface layer into reduced copper during the first period; Continue to introduce ammonia plasma for a second period, wherein the ammonia plasma dissociates to form nitrogen free radicals, and the nitrogen free radicals react with reduced copper to form a copper nitride layer covering the surface of the copper interconnect layer to release stress between copper grains in the copper interconnect layer; removing the copper nitride layer by a chemical mechanical polishing process; A carbon-doped silicon nitride layer is deposited on the chemical mechanical polishing surface.
2. The method for manufacturing a copper interconnect structure according to claim 1, wherein: The step of releasing the stress between the copper grains in the copper interconnect layer by bombarding the copper oxide surface layer with ammonia plasma in the first period so that the ammonia plasma converts the copper oxide surface layer into reduced copper in the first period comprises: The copper oxide surface layer is bombarded with ammonia plasma for a first period at a bombardment direction with an angle of 0° to 45° with respect to the vertical direction to release stress between copper grains in the copper interconnect layer, so that the ammonia plasma converts the copper oxide surface layer into reduced copper in the first period.
3. The method for manufacturing a copper interconnect structure according to claim 1, wherein: The step of releasing the stress between the copper grains in the copper interconnect layer by bombarding the copper oxide surface layer with ammonia plasma in the first period so that the ammonia plasma converts the copper oxide surface layer into reduced copper in the first period comprises: In an environment of 500W to 600W radio frequency power, ammonia plasma with a flow rate of 1000sccm to 1500sccm in a first period is bombarded onto the copper oxide surface layer to release the stress between copper grains in the copper interconnect layer, so that the ammonia plasma converts the copper oxide surface layer into reduced copper in the first period.
4. The method for manufacturing a copper interconnect structure according to claim 1, wherein: The step of continuing to introduce ammonia plasma for a second period, wherein the ammonia plasma dissociates to form nitrogen free radicals in the second period, and the nitrogen free radicals react with reduced copper to form a copper nitride layer covering the surface of the copper interconnect layer to release the stress between copper grains in the copper interconnect layer, comprises: The ammonia plasma of the second period is continuously bombarded toward the reduced copper in a bombardment direction with an angle of 0° to 45° with respect to the vertical direction. In the second period, the ammonia plasma dissociates to form nitrogen radicals. The nitrogen radicals react with the reduced copper to form a copper nitride layer covering the surface of the copper interconnect layer to release stress between copper grains in the copper interconnect layer.
5. The method for manufacturing a copper interconnect structure according to claim 1, wherein: The step of continuing to introduce ammonia plasma for a second period, wherein the ammonia plasma dissociates to form nitrogen free radicals in the second period, and the nitrogen free radicals react with reduced copper to form a copper nitride layer covering the surface of the copper interconnect layer to release the stress between copper grains in the copper interconnect layer, comprises: In an environment of radio frequency power in the range of 500W to 600W, the copper oxide surface layer is continuously bombarded with ammonia plasma with a flow rate of 1000sccm to 1500sccm during a second period, wherein the ammonia plasma dissociates to form nitrogen radicals, and the nitrogen radicals react with reduced copper to form a copper nitride layer covering the surface of the copper interconnect layer to release stress between copper grains in the copper interconnect layer.
6. The method for manufacturing a copper interconnect structure according to claim 1, wherein: Ammonia plasma is continuously introduced for a second period, wherein the ammonia plasma dissociates to form nitrogen radicals, and the nitrogen radicals react with reduced copper to form a copper nitride layer covering the surface of the copper interconnect layer to release the stress between the copper grains in the copper interconnect layer. In the step of: to 7. The method for manufacturing a copper interconnect structure according to claim 1, wherein: The step of removing the copper nitride layer by chemical mechanical polishing process comprises: removing the copper nitride layer by a chemical mechanical polishing process; The copper interconnect layer is removed by chemical mechanical polishing process with a thickness of to copper interconnect surface.