Method for forming a film thickness measurement region

Abstract

The application provides a film thickness measurement area forming method, which comprises the following steps: sequentially forming a dielectric layer and a functional layer on a laminated structure with a film thickness measurement area layer by layer, and performing patterned etching on the dielectric layer and the functional layer; wherein, when etching an etching alignment mark, etching a magnetic film, etching a top electrode, and etching a groove of a top metal wire, the film thickness measurement area is etched together. The film thickness measurement area forming method provided by the application can simplify the film layer structure of the film thickness measurement area, thereby improving the accuracy of thin film thickness measurement.

Description

Technical Field

[0001] This invention relates to the field of semiconductor process technology, and in particular to a method for forming a film thickness measurement region. Background Technology

[0002] Semiconductor manufacturing processes are complex and involve numerous steps. After thin film deposition, etching, and chemical mechanical planarization, online film thickness monitoring is essential to reflect process uniformity and stability. Film thickness monitoring can also identify problems in the manufacturing process, making it a crucial monitoring method in semiconductor manufacturing. Existing online film thickness monitoring methods simulate the film thickness in different areas of the chip during the process flow to provide feedback on film thickness information, aiming to monitor the process level. However, the complexity of semiconductor manufacturing processes leads to complex film structures in the film thickness measurement area, with numerous interfaces, frequently resulting in inaccurate measurements. Summary of the Invention

[0003] The method for forming the film thickness measurement area provided by the present invention can simplify the film layer structure of the film thickness measurement area, thereby improving the accuracy of film thickness measurement.

[0004] This invention provides a method for forming a film thickness measurement region, comprising:

[0005] A dielectric layer and a functional layer are sequentially formed layer by layer on a stacked structure with a film thickness measurement area, and the dielectric layer and the functional layer are patterned and etched; wherein,

[0006] The film thickness measurement area is etched simultaneously when etching the alignment marks, the magnetic thin film, the top electrode, and the groove of the top metal interconnect.

[0007] Optionally, a dielectric layer and a functional layer are sequentially formed layer by layer on a stacked structure having a film thickness measurement area, and the dielectric layer and the functional layer are patterned and etched, including:

[0008] A first bottom electrode layer is formed on a stacked structure having a bottom metal interconnect and a bottom through hole;

[0009] The alignment mark and the film thickness measurement area are etched together, and the etching endpoint is not higher than the bottom surface of the bottom metal connection line;

[0010] A second bottom electrode layer is formed, and the first bottom electrode layer and the second bottom electrode layer are patterned and etched.

[0011] Optionally, a dielectric layer and a functional layer are sequentially formed layer by layer on a stacked structure having a film thickness measurement area, and the dielectric layer and the functional layer are patterned and etched, including:

[0012] Provide a stacked structure with a bottom metal connection and a bottom through hole;

[0013] The alignment mark and the film thickness measurement area are etched together, and the etching endpoint is not higher than the bottom surface of the bottom metal connection line;

[0014] A bottom electrode layer is formed and the bottom electrode layer is patterned and etched.

[0015] Optionally, a dielectric layer and a functional layer are sequentially formed layer by layer on a stacked structure having a film thickness measurement area, and the dielectric layer and the functional layer are patterned and etched, including:

[0016] The alignment marks, film thickness measurement area, and bottom electrode pattern gaps are filled with a light-transmitting medium and planarized.

[0017] A magnetic thin film is formed, and the film thickness measurement area is etched together during the patterning etching of the magnetic thin film.

[0018] Optionally, after etching the film thickness measurement area, the method further includes:

[0019] The film thickness measurement area is etched, and the etching endpoint is not higher than the upper surface of the bottom electrode.

[0020] Optionally, a dielectric layer and a functional layer are sequentially formed layer by layer on a stacked structure having a film thickness measurement area, and the dielectric layer and the functional layer are patterned and etched, including:

[0021] The pattern gaps and film thickness measurement areas of the magnetic thin film are filled with a dielectric material and then planarized.

[0022] A top electrode layer is formed on the magnetic thin film;

[0023] When patterning the top electrode layer, the film thickness measurement area is also etched, and the etching endpoint is not higher than the upper surface of the bottom electrode.

[0024] Optionally, a dielectric layer and a functional layer are sequentially formed layer by layer on a stacked structure having a film thickness measurement area, and the dielectric layer and the functional layer are patterned and etched, including:

[0025] The patterned gaps in the top electrode layer and the film thickness measurement area are filled with a dielectric material until the upper surface of the dielectric material is higher than the upper surface of the top electrode, thereby planarizing the dielectric material.

[0026] Top through-hole etching is performed on the medium;

[0027] The groove for the top metal connection line and the film thickness measurement area are etched together.

[0028] Optionally, when etching the film thickness measurement area, the etching range is within the area surrounded by the edge line of the film thickness measurement area.

[0029] Optionally, when forming the dielectric layer, the dielectric layer includes at least one or both of silicon nitride and tetraethyl orthosilicate.

[0030] Optionally, etching the film thickness measurement area together with the alignment mark includes etching the film thickness measurement area together with any of the alignment marks in the bottom electrode, magnetic thin film, top electrode, top via, or top metal interconnect groove.

[0031] In the technical solution provided by this invention, by etching the film thickness measurement area simultaneously during the etching of alignment marks, the etching of the magnetic thin film, the etching of the top electrode, and the etching of the grooves for the top metal interconnects, the opaque film layer in the film thickness measurement area can be removed, leaving only an opaque bottom electrode layer as a measurement station. All film layers above the bottom electrode in the film thickness measurement area are transparent, thus enabling precise measurement of the film thickness measurement area's thickness. Since the film thickness measurement area is etched together with the memory array and peripheral circuitry during etching and planarization processes, the thickness changes in the film thickness measurement area can indirectly confirm the thickness of each film layer in the memory array and peripheral circuitry. Furthermore, because the etching of the film thickness measurement area is performed simultaneously during the etching of alignment marks, the etching of the magnetic thin film, the etching of the top electrode, and the etching of the grooves for the top metal interconnects, there is no need to fabricate a separate photomask, thus avoiding increased process costs. Attached Figure Description

[0032] Figure 1 This is a flowchart of a method for forming a film thickness measurement area according to an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the intermediate structure of a method for forming a film thickness measurement area according to another embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the intermediate structure of a method for forming a film thickness measurement area according to another embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of the intermediate structure of a method for forming a film thickness measurement area according to another embodiment of the present invention;

[0036] Figure 5 This is a schematic diagram of the intermediate structure of a method for forming a film thickness measurement area according to another embodiment of the present invention;

[0037] Figure 6 This is a schematic diagram of the intermediate structure of a method for forming a film thickness measurement area according to another embodiment of the present invention;

[0038] Figure 7 This is a schematic diagram of the intermediate structure of a method for forming a film thickness measurement area according to another embodiment of the present invention;

[0039] Figure 8 This is a schematic diagram of the intermediate structure of a method for forming a film thickness measurement area according to another embodiment of the present invention;

[0040] Figure 9 This is a schematic diagram of the intermediate structure of a method for forming a film thickness measurement area according to another embodiment of the present invention;

[0041] Figure 10 This is a schematic diagram of the intermediate structure of a method for forming a film thickness measurement area according to another embodiment of the present invention;

[0042] Figure 11 This is a schematic diagram of the intermediate structure of a method for forming a film thickness measurement area according to another embodiment of the present invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] This invention provides a method for forming a film thickness measurement area, such as... Figure 1 As shown, it includes:

[0045] A dielectric layer and a functional layer are sequentially formed layer by layer on a stacked structure with a film thickness measurement area, and the dielectric layer and the functional layer are patterned and etched; wherein,

[0046] The film thickness measurement area is etched simultaneously when etching the alignment marks, the magnetic thin film, the top electrode, and the groove of the top metal interconnect.

[0047] In some embodiments, the functional layer includes a bottom metal interconnect layer, a bottom via layer, a bottom electrode layer, a magnetic thin film layer, a top electrode layer, a top via layer, and a top metal interconnect layer; the dielectric layer includes a temporarily formed dielectric layer, such as a mask layer, which is removed in subsequent processing; the dielectric layer also includes a dielectric layer permanently retained in the semiconductor structure.

[0048] In the technical solution provided by this invention, by etching the alignment marks, the magnetic thin film, the top electrode, and the grooves of the top metal interconnects simultaneously, the opaque film layer in the film thickness measurement area can be removed, leaving only an opaque bottom electrode layer as the measurement station. All the film layers above the bottom electrode in the film thickness measurement area are transparent, thus enabling precise measurement of the film thickness measurement area's thickness. Since the film thickness measurement area is processed together with the memory array and peripheral circuitry during etching and planarization, the thickness changes in the film thickness measurement area can indirectly confirm the thickness of each film layer in the memory array and peripheral circuitry.

[0049] In some alternative embodiments, a dielectric layer and a functional layer are sequentially formed layer by layer on a stacked structure having a film thickness measurement region, and the dielectric layer and the functional layer are patterned and etched, including:

[0050] A first bottom electrode layer is formed on a stacked structure having a bottom metal interconnect and a bottom through hole;

[0051] The alignment mark and the film thickness measurement area are etched together, and the etching endpoint is not higher than the bottom surface of the bottom metal connection line;

[0052] A second bottom electrode layer is formed, and the first bottom electrode layer and the second bottom electrode layer are patterned and etched.

[0053] In some embodiments, the first bottom electrode layer is thin and transparent, so the photolithography process can directly align it during the etching of the first bottom electrode layer. In this embodiment, in order to ensure smooth photolithographic alignment during the subsequent etching of the second bottom electrode, alignment marks need to be formed first. During the formation of the alignment marks, the film thickness measurement area is etched simultaneously, so that after the formation of the second bottom electrode layer, the second bottom electrode layer is used as the measurement station. In some preferred embodiments, the thickness of the first bottom electrode layer can be 500 angstroms to 3000 angstroms.

[0054] As an optional implementation, a dielectric layer and a functional layer are sequentially formed layer by layer on a stacked structure having a film thickness measurement area, and the dielectric layer and the functional layer are patterned and etched, including:

[0055] Provide a stacked structure with a bottom metal connection and a bottom through hole;

[0056] The alignment mark and the film thickness measurement area are etched together, and the etching endpoint is not higher than the bottom surface of the bottom metal connection line;

[0057] A bottom electrode layer is formed and the bottom electrode layer is patterned and etched.

[0058] In some embodiments, the bottom electrode layer can also be formed in one step, i.e., alignment marks are directly etched onto the stacked structure having bottom vias and bottom metal interconnects, while the film thickness measurement area is also etched simultaneously. During subsequent formation of the bottom electrode layer, a bottom electrode layer is also formed in the film thickness measurement area, thus creating a thickness measurement station.

[0059] As an optional implementation, a dielectric layer and a functional layer are sequentially formed layer by layer on a stacked structure having a film thickness measurement area, and the dielectric layer and the functional layer are patterned and etched, including:

[0060] The alignment marks, film thickness measurement area, and bottom electrode pattern gaps are filled with a light-transmitting medium and planarized.

[0061] A magnetic thin film is formed, and the film thickness measurement area is etched together during the patterning etching of the magnetic thin film.

[0062] As an alternative implementation, since the magnetic thin film is an opaque material, in order to achieve the subsequent measurement process, the film thickness measurement area needs to be etched together when the magnetic thin film is patterned, so that only the transparent material is retained in the film thickness measurement area.

[0063] As an optional implementation, after etching the film thickness measurement area, the method further includes etching the film thickness measurement area, with the etching endpoint not exceeding the upper surface of the bottom electrode layer. In some embodiments, since the magnetic thin film is formed on the bottom electrode layer, in order to separate different magnetic thin film units, it is necessary to control the etching endpoint to be no higher than the upper surface of the bottom electrode layer.

[0064] As an optional implementation, a dielectric layer and a functional layer are sequentially formed layer by layer on a stacked structure having a film thickness measurement area, and the dielectric layer and the functional layer are patterned and etched, including:

[0065] The pattern gaps and film thickness measurement areas of the magnetic thin film are filled with a dielectric material and then planarized.

[0066] A top electrode layer is formed on the magnetic thin film;

[0067] When patterning the top electrode layer, the film thickness measurement area is also etched, and the etching endpoint is not higher than the upper surface of the bottom electrode.

[0068] In some embodiments, since the top electrode is also an opaque material, the film thickness measurement area needs to be etched along with the top electrode during patterning etching to ensure subsequent film thickness measurement. In some preferred embodiments, since the medium filling the gaps in the magnetic thin film pattern is usually different from the underlying medium, the etching endpoint can be set no higher than the upper surface of the bottom electrode to ensure the accuracy of the film thickness measurement results. This removes the medium filling the gaps in the magnetic thin film pattern, and the subsequent filling material is the same as the underlying medium. Therefore, the transmittance of the medium in the film thickness measurement area is the same, which is beneficial to the accuracy of film thickness measurement.

[0069] As an optional implementation, a dielectric layer and a functional layer are sequentially formed layer by layer on a stacked structure having a film thickness measurement area, and the dielectric layer and the functional layer are patterned and etched, including:

[0070] The patterned gaps in the top electrode layer and the film thickness measurement area are filled with a dielectric material until the upper surface of the dielectric material is higher than the upper surface of the top electrode, thereby planarizing the dielectric material.

[0071] Top through-hole etching is performed on the medium;

[0072] The groove for the top metal connection line and the film thickness measurement area are etched together.

[0073] In some embodiments, since the depth of the groove needs to be measured during the etching process of the top metal connecting wire groove, in order to obtain the depth of the groove, the film thickness measurement area is etched together in this embodiment. Thus, the depth of the groove is indirectly determined by the thickness change of the film thickness measurement area during the etching process.

[0074] As an optional implementation, when etching the film thickness measurement area, the etching range is within the area surrounded by the edge line of the film thickness measurement area. In some embodiments, the etching range of the film thickness measurement area is sufficient to achieve the measurement of the film thickness. Therefore, during the etching process, the entire film thickness measurement area can be etched, or only a local area can be etched.

[0075] As an optional implementation, when forming the dielectric layer, the dielectric layer includes at least one or both of silicon nitride and tetraethyl orthosilicate.

[0076] As an optional implementation, etching the film thickness measurement area together with the alignment mark includes etching the film thickness measurement area together with any of the alignment marks in the bottom electrode, magnetic film, top electrode, top via, or top metal interconnect groove.

[0077] The following provides an exemplary implementation method to specifically illustrate the embodiments of the present invention:

[0078] exist Figures 2 to 11 In the diagram, Array represents the storage cell array area, and PAD X represents the film thickness measurement area.

[0079] like Figure 2 As shown, PAD X is not opened when fabricating the bottom metal and via interconnect layers. That is, the layer structure corresponding to the bottom of PAD X, the metal, and the via interconnect layers are all dielectric layers. The dielectric layer can be a single-layer film or a multi-layer film.

[0080] like Figure 3 As shown, a thin layer of bottom electrode material, namely the first bottom electrode layer, is deposited on a flat surface. At this time, the first bottom electrode layer can transmit light, and the photolithography process can be aligned normally.

[0081] like Figure 4 As shown, after forming the second bottom electrode layer, alignment between the bottom electrode and the bottom metal interconnect layer is difficult because the bottom electrode is not light-transmitting. To achieve photolithographic alignment, photolithographic alignment marks need to be created first, and PAD X is turned on simultaneously when creating the photolithographic alignment marks. The photolithographic alignment marks are relatively deep, so the subsequent deposition of the bottom electrode metal layer will not fill the grooves of the photolithographic alignment marks. When aligning the bottom electrode and the bottom via interconnect layer, the exposure can be performed with the photolithographic alignment marks aligned with them.

[0082] like Figure 5 As shown, a bottom electrode film is deposited in the PAD X groove, and the bottom electrode film of PADX is retained when the bottom electrode is etched to form a pattern. This bottom electrode film is relatively thick and opaque, and can be used as an opaque metal layer for subsequent measurement stations.

[0083] like Figure 6 As shown, dielectric thin film deposition and chemical mechanical polishing are performed to ensure that PAD X can be filled and smoothed. Subsequently, a magnetic storage thin film is deposited on the smooth surface.

[0084] like Figure 7 As shown, the magnetic storage film on PAD X is etched away during the magnetic storage film etching process. Subsequently, one or two dielectric layers are deposited on PAD X, and the film thickness measurement PAD X is smoothed by chemical mechanical polishing. At this point, only the transparent dielectric layer exists on the opaque metal layer at the bottom of PAD X, which is superior to current film thickness measurement PADs. The film structure is relatively simple, which can greatly improve the accuracy of film thickness measurement and effectively improve the film thickness measurement problem after chemical mechanical polishing of magnetic storage film dielectrics.

[0085] like Figure 8 As shown, a top electrode film is deposited on the flat surface after the magnetic storage thin film medium has undergone chemical mechanical planarization.

[0086] like Figure 9 As shown, the top electrode film on PAD X is removed during top electrode etching. After depositing the dielectric film, chemical mechanical polishing is performed. At this point, a single-layer dielectric structure exists on the opaque metal layer at the bottom of the film thickness measurement PAD X, forming the most ideal film thickness measurement pad, greatly improving the accuracy of film thickness measurement after top electrode chemical mechanical polishing.

[0087] like Figure 10 As shown, PAD X is not opened during the top through-hole etching.

[0088] like Figure 11 As shown, PAD X is activated during the etching of the top metal interconnects. The presence of a single-layer dielectric structure on the opaque metal layer beneath PAD X improves the accuracy of depth measurement after the top metal interconnects are etched. Subsequent processes include metal deposition and chemical mechanical planarization polishing.

[0089] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for forming a film thickness measurement region, characterized in that, include: A dielectric layer and a functional layer are sequentially formed layer by layer on a stacked structure with a film thickness measurement area, and the dielectric layer and the functional layer are patterned and etched; wherein, When etching the alignment marks, the magnetic thin film, the top electrode, and the groove of the top metal connection, the film thickness measurement area is etched together, and the etching endpoint is not higher than the upper surface of the bottom electrode. The opaque film layer in the film thickness measurement area is etched away, leaving only an opaque bottom electrode layer in the film thickness measurement area as the measurement station. All the film layers above the bottom electrode in the film thickness measurement area are transparent film layers. When etching the film thickness measurement area, the etching range is within the area surrounded by the edge line of the film thickness measurement area.

2. The method according to claim 1, characterized in that, A dielectric layer and a functional layer are sequentially formed layer by layer on a stacked structure with a film thickness measurement area, and the dielectric layer and the functional layer are patterned and etched, including: A first bottom electrode layer is formed on a stacked structure having a bottom metal interconnect and a bottom through hole; The alignment mark and the film thickness measurement area are etched together, and the etching endpoint is not higher than the bottom surface of the bottom metal connection line; A second bottom electrode layer is formed, and the first bottom electrode layer and the second bottom electrode layer are patterned and etched.

3. The method according to claim 1, characterized in that, A dielectric layer and a functional layer are sequentially formed layer by layer on a stacked structure with a film thickness measurement area, and the dielectric layer and the functional layer are patterned and etched, including: Provide a stacked structure with a bottom metal connection and a bottom through hole; The alignment mark and the film thickness measurement area are etched together, and the etching endpoint is not higher than the bottom surface of the bottom metal connection line; A bottom electrode layer is formed and the bottom electrode layer is patterned and etched.

4. The method according to claim 2 or 3, characterized in that, A dielectric layer and a functional layer are sequentially formed layer by layer on a stacked structure with a film thickness measurement area, and the dielectric layer and the functional layer are patterned and etched, including: The alignment marks, film thickness measurement area, and bottom electrode pattern gaps are filled with a light-transmitting medium and planarized. A magnetic thin film is formed, and the film thickness measurement area is etched together during the patterning etching of the magnetic thin film.

5. The method according to claim 4, characterized in that, After etching the film thickness measurement area, the process also includes: The film thickness measurement area is etched, and the etching endpoint is not higher than the upper surface of the bottom electrode.

6. The method according to claim 4, characterized in that, A dielectric layer and a functional layer are sequentially formed layer by layer on a stacked structure with a film thickness measurement area, and the dielectric layer and the functional layer are patterned and etched, including: The pattern gaps and film thickness measurement areas of the magnetic thin film are filled with a dielectric material and then planarized. A top electrode layer is formed on the magnetic thin film; When patterning the top electrode layer, the film thickness measurement area is also etched, and the etching endpoint is not higher than the upper surface of the bottom electrode.

7. The method according to claim 6, characterized in that, A dielectric layer and a functional layer are sequentially formed layer by layer on a stacked structure with a film thickness measurement area, and the dielectric layer and the functional layer are patterned and etched, including: The patterned gaps in the top electrode layer and the film thickness measurement area are filled with a dielectric material until the upper surface of the dielectric material is higher than the upper surface of the top electrode, thereby planarizing the dielectric material. Top through-hole etching is performed on the medium; The groove for the top metal connection line and the film thickness measurement area are etched together.

8. The method according to claim 1, characterized in that, When forming the dielectric layer, the dielectric layer comprises at least one or both of silicon nitride and tetraethyl orthosilicate.

9. The method according to claim 1, characterized in that, Etching the film thickness measurement area together with the alignment mark includes etching the film thickness measurement area together with any of the alignment marks in the bottom electrode, magnetic thin film, top electrode, top via, or top metal interconnect groove.

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