A self-aligned dual patterned core removal method
By dividing the region and forming sidewalls in a self-aligned dual-pattern structure, the problem of sidewall bending during mandrel removal was solved, achieving complete removal of the mandrel structure and ensuring process reliability.
Patent Information
- Application Number
- CN202211005694.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-08-22
- Publication Date
- 2026-02-03
- Estimated Expiration
- 2042-08-22
AI Technical Summary
In the process of removing the mandrel of a self-aligned dual-pattern structure, the existing technology requires different regions to be etched with isotropic and anisotropic methods, which causes sidewall bending and affects the subsequent metal hard mask etching process.
By dividing the stacked structure into first and second regions, mandrel structures of different sizes are formed respectively, and sidewalls are formed through multilayer film layers and etching steps, ensuring the complete removal of the mandrel structure and avoiding sidewall bending.
This method enables the complete removal of the mandrel structure in different regions, avoids sidewall bending, solves the defect problem in the subsequent metal hard mask etching process, and ensures the reliability and accuracy of the process.
Smart Images
Figure CN115332182B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor technology, and in particular to a method for removing a mandrel from a self-aligned dual-patterned structure. Background Technology
[0002] In integrated circuit manufacturing processes, with the continuous advancement of technology nodes, especially for 24nm and below, the ability to define the critical dimensions of related structures using photolithography has reached its limit. To obtain smaller structures, self-aligned dual-patterning technology has been introduced. S alf A ligned D ouble P (SADP process). Taking the later stage of SADP process as an example, amorphous silicon is used as the core film layer. The specific process includes: forming the film layer structure before etching; performing the etching process of the core structure to form the core structure; depositing sidewalls on both sides of the core structure; performing sidewall etching; performing the core removal exposure process to form the film layer before sidewall removal etching. Then, the core structure removal process is performed. For a certain area, the core between the sidewalls needs to be completely removed, but for another area, the thickness of the sidewalls alone cannot completely define the critical dimensions of the subsequent pattern. Therefore, in this process, part of the core structure needs to be retained; the remaining film layer is used as a mask layer for the subsequent metal hard mask etching process. For the core material removal process step in the above process flow, for a certain area, this step requires a certain degree of isotropic etching to ensure that the core material is completely removed. However, in another area, the influence of isotropic etching will form a sidewall bending morphology in the remaining core material. Furthermore, this curved shape will have a further impact on the subsequent metal hard mask etching process, causing damage and other problems. Summary of the Invention
[0003] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a mandrel removal method for a self-aligned dual-pattern structure, which solves the problem of sidewall bending caused by the need for isotropic and anisotropic etching to remove the mandrel in different areas of the SADP process in the prior art.
[0004] To achieve the above and other related objectives, the present invention provides a method for removing a mandrel with a self-aligned dual-pattern structure, comprising at least:
[0005] Step 1: Provide a stack of layers, which are formed from bottom to top by an etch stop layer, a metal hard mask layer, and a core etch stop layer; divide the stack into a first region and a second region along its longitudinal direction;
[0006] Step 2: Form multiple mandrel structures arranged at intervals on the mandrel etch stop layers in the first and second regions respectively; wherein the mandrel structure located on the mandrel etch stop layer in the first region is the first mandrel structure; and the mandrel structure located on the mandrel etch stop layer in the second region is the second mandrel structure.
[0007] Step 3: Deposit a first film layer to cover the upper surface of the mandrel etching stop layer and the outer surfaces of the first and second mandrel structures;
[0008] Step 4: Etch the first film layer to remove the first film layer on the top of the first and second mandrel structures and the first film layer on the upper surface of the mandrel etching stop layer, forming a first sidewall on the sidewall of the first and second mandrel structures.
[0009] Step 5: Form an organic dielectric layer covering the mandrel etch stop layer and the first and second mandrel structures; form a silicon-containing anti-reflective layer on the organic dielectric layer; then coat the silicon-containing anti-reflective layer with photoresist.
[0010] Step 6: Expose and develop to expose the silicon-containing anti-reflective layer in the first region;
[0011] Step 7: Etch away the silicon-containing anti-reflective layer and the organic dielectric layer on the first region to expose the first mandrel structure;
[0012] Step 8: Remove the first sidewall on the first mandrel structure; then ashing the remaining organic dielectric layer to remove the organic dielectric layer covering the second region;
[0013] Step 9: Deposit a second film layer, which covers the mandrel etching stop layer and the first sidewall of the upper surface and sidewall of the first mandrel structure and the second mandrel structure.
[0014] Step 10: Etch the second film layer to remove the second film layer on the upper surface of the mandrel etching stop layer, the second film layer on the upper surface of the first mandrel structure, the second film layer on the upper surface of the second mandrel structure and its first sidewall; form a second sidewall on the sidewall of the first mandrel structure, and form a second sidewall attached to the sidewall of the second mandrel structure of the first sidewall;
[0015] Step 11: Remove the first and second mandrel structures; form the first sidewalls arranged at intervals on the mandrel etching stop layer in the first region; form a combined structure of the first and second sidewalls arranged at intervals on the mandrel etching stop layer in the second region;
[0016] Step 12: Using the first sidewall and the combined structure of the first and second sidewalls as a mask, etch the mandrel etching stop layer and the metal hard mask layer until etching reaches the upper surface of the etching stop layer.
[0017] Preferably, the metal hard mask layer in step one is TiN.
[0018] Preferably, the mandrel etching stop layer in step one is a silicon oxide layer.
[0019] Preferably, the critical dimension of the first mandrel structure in step two is smaller than the critical dimension of the second mandrel structure.
[0020] Preferably, the first film layer in step three is silicon nitride.
[0021] Preferably, the mandrel structure in step two is amorphous silicon.
[0022] Preferably, in step eight, the first sidewall on the first mandrel structure is removed by wet etching.
[0023] As described above, the mandrel removal method for the self-aligned dual-patterned structure of the present invention has the following beneficial effects: The present invention has the same process requirements for the first and second regions, requiring only the complete removal of the mandrel structure material. The remaining film structure after etching in both regions consists of sidewalls, preventing sidewall bending and thus solving the defect problems generated in subsequent hard metal hard mask etching processes. Attached Figure Description
[0024] Figures 1 to 10 The diagram shows the structural schematics of each stage in the mandrel removal method of the self-aligned dual-pattern structure of the present invention.
[0025] Figure 11 The flowchart shown is a method for removing the mandrel of the self-aligned dual-pattern structure of the present invention. Detailed Implementation
[0026] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0027] Please see Figures 1 to 11It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.
[0028] This invention provides a method for removing a mandrel with a self-aligned dual-pattern structure, such as... Figure 11 As shown, Figure 11 The flowchart shown illustrates a mandrel removal method for a self-aligned dual-pattern structure according to the present invention, which includes at least the following steps:
[0029] Step 1: Provide a stack of layers, which are formed from bottom to top by an etch stop layer, a metal hard mask layer, and a core etch stop layer; divide the stack into a first region and a second region along its longitudinal direction;
[0030] In a further embodiment of the present invention, the metal hard mask layer in step one is TiN.
[0031] In a further embodiment of the present invention, the mandrel etching stop layer in step one is a silicon oxide layer.
[0032] like Figure 1 As shown, step one provides a stack of layers, which are stacked sequentially from bottom to top as an etch stop layer 01, a metal hard mask layer 02, and a mandrel etch stop layer 03; the stack is divided into a first region (region A) and a second region (region B) along the longitudinal direction of the stack; the metal hard mask layer is TiN; and the mandrel etch stop layer is a silicon oxide layer.
[0033] Step 2: Form multiple mandrel structures arranged at intervals on the mandrel etch stop layers in the first and second regions respectively; wherein the mandrel structure located on the mandrel etch stop layer in the first region is the first mandrel structure; and the mandrel structure located on the mandrel etch stop layer in the second region is the second mandrel structure.
[0034] Furthermore, in step two of this embodiment, the critical dimension of the first mandrel structure is smaller than the critical dimension of the second mandrel structure.
[0035] Furthermore, in this embodiment, the mandrel structure in step two is amorphous silicon.
[0036] like Figure 1As shown, in step two, multiple mandrel structures 04 are formed at intervals on the mandrel etch stop layers in the first and second regions, respectively; wherein the mandrel structure located on the mandrel etch stop layer in the first region is the first mandrel structure; the mandrel structure located on the mandrel etch stop layer in the second region is the second mandrel structure; the critical dimension of the first mandrel structure is smaller than the critical dimension of the second mandrel structure. The mandrel structure is amorphous silicon.
[0037] Step 3: Deposit a first film layer to cover the upper surface of the mandrel etching stop layer and the outer surfaces of the first and second mandrel structures;
[0038] Furthermore, in this embodiment, the first film layer in step three is silicon nitride. For example... Figure 2 As shown, in step three, a first film layer 05 is deposited to cover the upper surface of the mandrel etching stop layer and the outer surfaces of the first and second mandrel structures; the first film layer 05 is silicon nitride.
[0039] Step 4: Etch the first film layer to remove the first film layer on the top of the first and second mandrel structures and the first film layer on the upper surface of the mandrel etching stop layer, forming a first sidewall on the sidewall of the first and second mandrel structures; Figure 3 As shown, in step four, the first film layer 05 is etched, so that the first film layer 05 on the top of the first and second mandrel structures and the first film layer 05 on the upper surface of the mandrel etching stop layer 03 are removed, and a first sidewall 06 is formed on the sidewall of the first and second mandrel structures.
[0040] Step 5: Form an organic dielectric layer covering the mandrel etch stop layer and the first and second mandrel structures; form a silicon-containing anti-reflective layer on the organic dielectric layer; then coat the silicon-containing anti-reflective layer with photoresist; as shown below. Figure 4 As shown, step five forms an organic dielectric layer 07, which covers the mandrel etching stop layer 03 and the first and second mandrel structures 04; a silicon-containing anti-reflective layer 08 is formed on the organic dielectric layer 07; and then photoresist 09 is coated on the silicon-containing anti-reflective layer 08.
[0041] Step Six: Expose and develop to expose the silicon-containing anti-reflective layer in the first region; as shown Figure 4 As shown, that is, after development, the second region is still covered with photoresist 09.
[0042] Step 7: Etch away the silicon-containing anti-reflective layer and the organic dielectric layer on the first region to expose the first mandrel structure; as shown Figure 5As shown, in step seven, the silicon-containing anti-reflective layer and the organic dielectric layer on the first region are etched away to expose the first mandrel structure, while the second region is still covered by the organic dielectric layer 07.
[0043] Step 8: Remove the first sidewall on the first mandrel structure; then ashing the remaining organic dielectric layer to remove the organic dielectric layer covering the second region;
[0044] In a further step of this invention, in step eight of this embodiment, the first sidewall on the first mandrel structure is removed by wet etching. For example... Figure 6 As shown, in this embodiment, the first sidewall 06 on the first mandrel structure is removed by wet etching.
[0045] Step 9: Deposit a second film layer, which covers the mandrel etching stop layer and the first sidewalls of the upper surfaces and sidewalls of the first mandrel structure and the second mandrel structure; as shown Figure 7 As shown, in step nine, a second film layer 10 is deposited, which covers the mandrel etching stop layer and the first sidewall 06 of the upper surface and sidewalls of the first mandrel structure and the second mandrel structure.
[0046] Step 10: Etch the second film layer to remove the second film layer on the upper surface of the mandrel etching stop layer, the second film layer on the upper surface of the first mandrel structure, the second film layer on the upper surface of the second mandrel structure and its first sidewall; form a second sidewall on the sidewall of the first mandrel structure, and form a second sidewall attached to the sidewall of the second mandrel structure; as shown Figure 8 As shown, in step ten, the second film layer is etched to remove the second film layer on the upper surface of the mandrel etching stop layer, the second film layer on the upper surface of the first mandrel structure, the second film layer on the upper surface of the second mandrel structure and its first sidewall; a second sidewall is formed on the sidewall of the first mandrel structure, and a second sidewall 11 is formed attached to the sidewall of the second mandrel structure and the first sidewall.
[0047] Step 11: Remove the first and second mandrel structures; form the first sidewalls arranged at intervals on the mandrel etching stop layer in the first region; form a combined structure of the first and second sidewalls arranged at intervals on the mandrel etching stop layer in the second region; as shown. Figure 9As shown, in step eleven, the first and second mandrel structures are removed, and the first sidewalls 06 arranged at intervals are formed on the mandrel etching stop layer in the first region; a combined structure of the first and second sidewalls 11 arranged at intervals is formed on the mandrel etching stop layer in the second region. That is, the first and second sidewalls in the second region are attached to each other to form the combined structure.
[0048] Step 12: Using the first sidewall and the combined structure of the first and second sidewalls as a mask, etch the mandrel etching stop layer and the metal hard mask layer until etching reaches the upper surface of the etching stop layer. Figure 10 As shown, in step 12, the mandrel etching stop layer and the metal hard mask layer are etched using the first sidewall and the combination structure of the first and second sidewalls as a mask until the etching reaches the upper surface of the etching stop layer, forming the mandrel etching stop layer structure 13 and the metal hard mask layer structure 12 located thereunder.
[0049] In summary, the present invention has the same process requirements for both the first and second regions, requiring only the complete removal of the mandrel structure material. The remaining film structure after etching in both regions consists of sidewalls, preventing sidewall bending and thus resolving defects encountered in subsequent hard metal mask etching processes. Therefore, the present invention effectively overcomes various shortcomings of existing technologies and possesses high industrial applicability.
[0050] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.
Claims
1. A method for removing a mandrel with a self-aligned dual-pattern structure, characterized in that, At least including: Step 1: Provide a stack of layers, which are formed from bottom to top by an etch stop layer, a metal hard mask layer, and a core etch stop layer; divide the stack into a first region and a second region along its longitudinal direction; Step 2: Form multiple mandrel structures arranged at intervals on the mandrel etch stop layers in the first and second regions respectively; wherein the mandrel structure located on the mandrel etch stop layer in the first region is the first mandrel structure; and the mandrel structure located on the mandrel etch stop layer in the second region is the second mandrel structure. Step 3: Deposit a first film layer to cover the upper surface of the mandrel etching stop layer and the outer surfaces of the first and second mandrel structures; Step 4: Etch the first film layer to remove the first film layer on the top of the first and second mandrel structures and the first film layer on the upper surface of the mandrel etching stop layer, forming a first sidewall on the sidewall of the first and second mandrel structures. Step 5: Form an organic dielectric layer covering the mandrel etch stop layer and the first and second mandrel structures; form a silicon-containing anti-reflective layer on the organic dielectric layer; then coat the silicon-containing anti-reflective layer with photoresist. Step 6: Expose and develop to expose the silicon-containing anti-reflective layer in the first region; Step 7: Etch away the silicon-containing anti-reflective layer and the organic dielectric layer on the first region to expose the first mandrel structure; Step 8: Remove the first sidewall on the first mandrel structure; then ashing the remaining organic dielectric layer to remove the organic dielectric layer covering the second region; Step 9: Deposit a second film layer, which covers the mandrel etching stop layer and the first sidewall of the upper surface and sidewall of the first mandrel structure and the second mandrel structure. Step 10: Etch the second film layer to remove the second film layer on the upper surface of the mandrel etching stop layer, the second film layer on the upper surface of the first mandrel structure, the second film layer on the upper surface of the second mandrel structure and its first sidewall; form a second sidewall on the sidewall of the first mandrel structure, and form a second sidewall attached to the sidewall of the second mandrel structure of the first sidewall; Step 11: Remove the first and second mandrel structures; form the first sidewalls arranged at intervals on the mandrel etching stop layer in the first region; form a combined structure of the first and second sidewalls arranged at intervals on the mandrel etching stop layer in the second region; Step 12: Using the first sidewall and the combined structure of the first and second sidewalls as a mask, etch the mandrel etching stop layer and the metal hard mask layer until etching reaches the upper surface of the etching stop layer.
2. The mandrel removal method for a self-aligned dual-pattern structure according to claim 1, characterized in that: The metal hard mask layer mentioned in step one is TiN.
3. The mandrel removal method for a self-aligned dual-pattern structure according to claim 1, characterized in that: The mandrel etching stop layer in step one is a silicon oxide layer.
4. The mandrel removal method for a self-aligned dual-pattern structure according to claim 1, characterized in that: In step two, the critical dimension of the first mandrel structure is smaller than the critical dimension of the second mandrel structure.
5. The mandrel removal method for a self-aligned dual-pattern structure according to claim 1, characterized in that: The first film layer in step three is silicon nitride.
6. The mandrel removal method for a self-aligned dual-pattern structure according to claim 1, characterized in that: The mandrel structure mentioned in step two is amorphous silicon.
7. The mandrel removal method for a self-aligned dual-pattern structure according to claim 1, characterized in that: In step eight, the first sidewall on the first mandrel structure is removed by wet etching.
Citation Information
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