Manufacturing method of small-size contact hole
By deposition and back-etching barrier layers to form a trumpet-like contact hole structure in semiconductor integrated circuit manufacturing, the problem of small-sized contact holes filling voids is solved and the coverage of the aluminum deposition process is improved.
Patent Information
- Application Number
- CN202411205244.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-30
- Publication Date
- 2024-12-13
AI Technical Summary
In semiconductor integrated circuit manufacturing, small-sized contact holes are filled with aluminum due to the self-shielding effect of the physical vapor deposition process, resulting in residual passivation layer and aluminum fluoride in the contact holes, causing the problem of aluminum filling voids.
By depositing the protective layer, the dielectric layer and the photoresist layer on the copper interconnect structure, the primary structure of the contact hole is etched to form the contact hole primary structure, the photoresist layer is removed, and the barrier layer is deposited and back-etched, so that the upper diameter of the contact hole is expanded to form a horn shape, thereby filling aluminum to avoid voids.
The step coverage of the aluminum deposition process is improved, and the gap problem arises due to the deposition of atoms covering the contact hole openings is avoided.
Smart Images
Figure CN119133090A_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 small-size contact hole. Background Art
[0002] The back-end copper interconnection process is a commonly used process technology in the current semiconductor manufacturing process, in which aluminum contact holes are usually required to be formed on the top layer of the back-end copper interconnection process. With the diversification of customer needs, when filling aluminum in small critical size (CD about <3um) contact holes, due to the self-shielding effect of the physical vapor deposition process, the atoms accumulated on the top cover the opening of the contact hole, making it difficult for subsequent atoms to deposit in the contact hole, resulting in aluminum filling gaps. In addition, there will be passivation layer and aluminum fluoride residues in the gaps in the subsequent passivation layer process. Summary of the invention
[0003] The present application provides a method for manufacturing a small-sized contact hole, which can solve the problem of filling gaps in the related art.
[0004] In order to solve the technical problem in the background technology of the present application, the present application provides a method for manufacturing a small-sized contact hole, and the method for manufacturing a small-sized contact hole comprises the following steps:
[0005] Depositing a protective layer, a dielectric layer and a photoresist layer in sequence on the copper interconnect structure;
[0006] defining a small-sized contact hole pattern in the photoresist layer;
[0007] Based on the photoresist layer with the small-size contact hole pattern, etching the dielectric layer until the protective layer is exposed to form a primary structure of the contact hole;
[0008] Depositing a barrier layer after removing the photoresist layer, wherein the barrier layer is filled in the contact hole primary structure;
[0009] Etching back the barrier layer so that the upper portion of the primary structure of the contact hole not covered by the barrier layer is enlarged to form a trumpet shape;
[0010] Removing the remaining barrier layer to form a contact hole, wherein the contact hole includes a straight lower portion and a trumpet-shaped upper portion that are connected;
[0011] The protective layer at the location of the contact hole is removed and aluminum is deposited, and the aluminum fully fills the contact hole.
[0012] Optionally, in the step of depositing a barrier layer after removing the photoresist layer and filling the barrier layer in the contact hole primary structure, the height of the upper surface of the barrier layer is lower than the height of the upper surface of the dielectric layer.
[0013] Optionally, in the step of depositing a barrier layer after removing the photoresist layer and filling the barrier layer in the contact hole primary structure, the height of the barrier layer is one third to three quarters of the height of the contact hole primary structure.
[0014] Optionally, the protective layer is made of SiCN.
[0015] Optionally, the barrier layer is made of Barc.
[0016] Optionally, the step of etching back the barrier layer so that the upper portion of the primary structure of the contact hole not covered by the barrier layer is enlarged to form a trumpet shape comprises:
[0017] The barrier layer is back-etched with a higher etching selectivity than the dielectric layer, so that the upper diameter of the primary structure of the contact hole not covered by the barrier layer is enlarged to form a trumpet shape.
[0018] Optionally, the step of removing the remaining barrier layer to form a contact hole, wherein the contact hole comprises a straight lower portion and a trumpet-shaped upper portion that are connected, comprises:
[0019] The remaining barrier layer is removed by an ashing process to form a contact hole, wherein the contact hole includes a straight lower portion and a trumpet-shaped upper portion that are connected.
[0020] The technical solution of the present application includes at least the following advantages: by first removing the photoresist layer and then depositing the barrier layer, the barrier layer is filled in the primary structure of the contact hole, and then the barrier layer is etched back so that the upper diameter of the primary structure of the contact hole not covered by the barrier layer is enlarged to form a trumpet shape, so that the diameter of the upper part of the formed contact hole gradually increases from bottom to top, avoiding the problem of deposition gaps caused by the deposited atoms shielding the opening of the contact hole in the subsequent aluminum deposition process, and improving the step coverage of the aluminum deposition process. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] 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.
[0022] Figure 1 A flow chart of a method for manufacturing a small-size contact hole is shown;
[0023] Figure 2 A schematic diagram of a cross-sectional structure of the device after step S1 is completed is shown;
[0024] Figure 3A schematic diagram of the cross-sectional structure of the device after step S3 is completed is shown;
[0025] Figure 4 A schematic diagram of the cross-sectional structure of the device after step S4 is completed is shown;
[0026] Figure 5 A schematic diagram of the cross-sectional structure of the device after step S5 is completed is shown;
[0027] Figure 6 FIG. 4 shows a schematic diagram of a cross-sectional structure of the device after step S6 is completed. DETAILED DESCRIPTION
[0028] 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, rather than all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.
[0029] 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.
[0030] 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.
[0031] 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.
[0032] Figure 1 The flow chart of the method for manufacturing small-size contact holes is shown. Figure 1 As can be seen from the figure, the method for manufacturing a small-size contact hole comprises the following steps:
[0033] Step S1: depositing a protection layer, a dielectric layer and a photoresist layer in sequence on the copper interconnect structure.
[0034] Figure 2 FIG. 4 shows a schematic diagram of the cross-sectional structure of the device after step S1 is completed. Figure 2 It can be seen that a protection layer 120 , a dielectric layer 130 and a photoresist layer 140 are sequentially deposited on the copper interconnect structure 110 .
[0035] Exemplarily, the material of the protection layer 110 is SiCN, and the material of the dielectric layer 130 can be PEOX.
[0036] Step S2: defining a small-sized contact hole pattern in the photoresist layer.
[0037] Step S3: Based on the photoresist layer with the small-size contact hole pattern, the dielectric layer is etched until the protection layer is exposed to form a primary contact hole structure.
[0038] Figure 3 The schematic diagram of the cross-sectional structure of the device after step S3 is completed is shown. Figure 3 It can be seen that a small-sized contact hole pattern is formed in the photoresist layer 140 , and the dielectric layer 130 is further etched based on the small-sized contact hole pattern to form a contact hole primary structure 200 , and the protection layer 120 is exposed from the contact hole primary structure 200 .
[0039] Step S4: after removing the photoresist layer, depositing a barrier layer, wherein the barrier layer is filled in the contact hole primary structure.
[0040] Figure 4 The schematic diagram of the cross-sectional structure of the device after step S4 is completed is shown. Figure 4 As can be seen in FIG. 1 , the barrier layer 300 is filled in the contact hole primary structure 200 .
[0041] The material of the barrier layer 300 is Barc.
[0042] For example, the photoresist layer 140 can be removed first, and then the barrier layer 300 can be deposited. The deposited barrier layer 300 fills the contact hole primary structure 200. The upper surface height of the barrier layer 300 is below the height of the upper surface of the dielectric layer 130, so that the upper top corner of the contact hole primary structure 200 is not covered by the barrier layer 300 and is exposed.
[0043] Optionally, the height of the barrier layer 300 is one third to three quarters of the height of the contact hole primary structure 200 .
[0044] Step S5: etching back the barrier layer so that the upper portion of the primary structure of the contact hole not covered by the barrier layer is enlarged to form a trumpet shape.
[0045] Figure 5 FIG. 4 shows a schematic diagram of the cross-sectional structure of the device after step S5 is completed. Figure 5 It can be seen from the figure that the upper portion of the contact hole primary structure 200 not covered by the barrier layer 300 is etched to form a trumpet-shaped opening during the etching back of the barrier layer 300 .
[0046] Illustratively, the entire wafer is blanket etched to etch back the barrier layer 300, so that the remaining barrier layer retains a certain height, and the remaining barrier layer protects the covered area, so that the upper diameter of the contact hole primary structure 200 not covered by the barrier layer 300 is enlarged to form a trumpet shape.
[0047] Optionally, the barrier layer is etched back with a higher etching selectivity than the dielectric layer, so that the upper portion of the contact hole primary structure not covered by the barrier layer is enlarged to form a trumpet shape.
[0048] Step S6: removing the remaining barrier layer to form a contact hole, wherein the contact hole includes a straight lower portion and a trumpet-shaped upper portion that are connected.
[0049] Figure 6 The schematic diagram of the cross-sectional structure of the device after step S6 is completed is shown. Figure 6 It can be seen from the figure that after removing the remaining barrier layer, a contact hole 400 is formed. The contact hole 400 includes a straight lower portion 410 and a trumpet-shaped upper portion 420 that are connected.
[0050] Exemplarily, the remaining barrier layer is removed by an ashing process to form a contact hole, wherein the contact hole includes a straight lower portion and a trumpet-shaped upper portion that are connected.
[0051] Step S7: removing the protective layer at the location of the contact hole and depositing aluminum, wherein the aluminum completely fills the contact hole.
[0052] In this embodiment, the photoresist layer is first removed and then a barrier layer is deposited, the barrier layer is filled in the primary structure of the contact hole, and then the barrier layer is etched back to expand the upper diameter of the primary structure of the contact hole not covered by the barrier layer to form a trumpet shape, so that the diameter of the upper part of the formed contact hole gradually increases from bottom to top, thereby avoiding the problem of deposition gaps caused by the deposited atoms shielding the opening of the contact hole in the subsequent aluminum deposition process, and improving the step coverage of the aluminum deposition process.
[0053] 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 manufacturing a small-size contact hole, characterized in that: The method for manufacturing a small-size contact hole comprises the following steps: Depositing a protective layer, a dielectric layer and a photoresist layer in sequence on the copper interconnect structure; defining a small-sized contact hole pattern in the photoresist layer; Based on the photoresist layer with the small-size contact hole pattern, etching the dielectric layer until the protective layer is exposed to form a primary structure of the contact hole; Depositing a barrier layer after removing the photoresist layer, wherein the barrier layer is filled in the contact hole primary structure; Etching back the barrier layer so that the upper portion of the primary structure of the contact hole not covered by the barrier layer is enlarged to form a trumpet shape; Removing the remaining barrier layer to form a contact hole, wherein the contact hole includes a straight lower portion and a trumpet-shaped upper portion that are connected; The protective layer at the location of the contact hole is removed and aluminum is deposited, and the aluminum fully fills the contact hole.
2. The method for manufacturing a small-size contact hole according to claim 1, wherein: In the step of depositing a barrier layer after removing the photoresist layer and filling the barrier layer in the contact hole primary structure, the height of the upper surface of the barrier layer is lower than the height of the upper surface of the dielectric layer.
3. The method for manufacturing a small-size contact hole according to claim 1, wherein: In the step of depositing a barrier layer after removing the photoresist layer and filling the barrier layer in the contact hole primary structure, the height of the barrier layer is one third to three quarters of the height of the contact hole primary structure.
4. The method for manufacturing a small-size contact hole according to claim 1, wherein: The material of the protective layer is SiCN.
5. The method for manufacturing a small-size contact hole according to claim 1, wherein: The material of the barrier layer is Barc.
6. The method for manufacturing a small-size contact hole according to claim 1, wherein: The step of etching back the barrier layer so that the upper portion of the primary structure of the contact hole not covered by the barrier layer is enlarged to form a trumpet shape comprises: The barrier layer is back-etched with a higher etching selectivity than the dielectric layer, so that the upper diameter of the primary structure of the contact hole not covered by the barrier layer is enlarged to form a trumpet shape.
7. The method for manufacturing a small-size contact hole according to claim 1, wherein: The step of removing the remaining barrier layer to form a contact hole, wherein the contact hole includes a straight lower portion and a trumpet-shaped upper portion that are connected, comprises: The remaining barrier layer is removed by an ashing process to form a contact hole, wherein the contact hole includes a straight lower portion and a trumpet-shaped upper portion that are connected.