An abnormality processing method for dry etching in an aluminum-based superconducting circuit

Abstract

This invention provides a method for handling anomalies in dry etching of aluminum-based superconducting circuits, comprising the following steps: (1) providing a sample; (2) heating the sample, and then etching the exposed aluminum metal layer using dry etching to expose the dielectric layer, and then immediately cleaning the etched sample with deionized water or oxalic acid and drying it; (3) etching the exposed dielectric layer using dry etching; (4) repeating steps (2) and (3) sequentially until both the exposed aluminum metal layer and the dielectric layer are etched away, exposing the substrate; (5) removing the residual photoresist layer. Using the anomaly handling method provided by this invention, the risk of morphological anomalies and blockage after deep trench etching in the dry etching process of aluminum-based superconducting circuits can be effectively avoided, and the method is easy to operate.

Description

Technical Field

[0001] This invention belongs to the field of superconducting circuit etching technology, and relates to an anomaly handling method for dry etching in aluminum-based superconducting circuits. Specifically, it relates to an anomaly handling method that can avoid the appearance of "pillars" during the dry etching process of aluminum-based superconducting circuits, thereby preventing the groove from being blocked. Background Technology

[0002] In the fabrication of multilayer metal wiring in aluminum-based superconducting circuits, the etching and grooving process is particularly complex, requiring precise etching of narrow grooves. The ideal structural diagrams before and after etching are shown below. Figure 1 and Figure 2 As shown, due to the large depth-to-width ratio and the complex film structure with three or more pairs of overlapping aluminum and dielectric layers in the vertical direction of the trench, multiple alternating etching processes of the aluminum and dielectric layers are involved. During the etching of the aluminum layer, aluminum oxide particles often form due to aluminum corrosion. These particles act as etching micromasks, and as the etching of the underlying film layers continues, the masking effect leaves tall "pillars" tightly attached to the sidewalls within the trench. In severe cases, these "pillars" can completely block the trench.

[0003] Therefore, in this field, there is a desire to develop an abnormal handling method that can avoid the occurrence of "pillars" during the dry etching process of aluminum-based superconducting circuits. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide an anomaly handling method for dry etching in aluminum-based superconducting circuits. Specifically, it relates to an anomaly handling method that avoids the formation of "pillars" during the dry etching process in aluminum-based superconducting circuits, thereby preventing the trench from being blocked. Using the anomaly handling method provided by this invention, the formation of tall "pillars" closely adhering to the sidewalls within the trench, caused by aluminum corrosion and other factors, can be avoided during the dry etching process of aluminum-based superconducting circuits, preventing the trench from being blocked.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for handling anomalies in dry etching in aluminum-based superconducting circuits, the anomaly handling method comprising the following steps:

[0007] (1) Provide samples:

[0008] A stacked structure comprising multiple aluminum metal layers and multiple dielectric layers is formed on one side of a substrate, wherein the aluminum metal layers and the dielectric layers are alternately arranged, and in the stacked structure, the dielectric layer is closest to the substrate and the aluminum metal layer is furthest from the substrate.

[0009] A photoresist layer is formed on the side of the stacked structure away from the substrate, and the photoresist layer is patterned. The patterned photoresist layer includes at least one groove to obtain a sample.

[0010] (2) Heat the sample and then use dry etching to etch the aluminum metal layer exposed by the groove in step (1), expose the dielectric layer by the groove, and then immediately clean the etched sample with deionized water or oxalic acid and blow it dry.

[0011] (3) The exposed dielectric layer in the trench is etched using a dry etching method;

[0012] (4) Repeat steps (2) and (3) in sequence until the exposed aluminum metal layer and dielectric layer are etched away to expose the substrate.

[0013] (5) Remove the residual photoresist layer;

[0014] Step (2) involves immediately cleaning the etched sample with deionized water or oxalic acid, specifically including the following steps:

[0015] Immediately rinse or wash the etched sample with deionized water for 0.5-10.0 min (e.g., 0.5 min, 1 min, 1.5 min, 2.0 min, 2.5 min, 3.0 min, 3.5 min, 4.0 min, 5.0 min, 6.0 min, 7.0 min, 8.0 min, 9.0 min, or 10.0 min, etc.), or immediately wash the etched sample with oxalic acid for 0.5-10.0 min (e.g., 0.5 min, 1 min, 1.5 min, 2.0 min, 2.5 min, 3.0 min, 3.5 min, 4.0 min, 5.0 min, 6.0 min, 7.0 min, 8.0 min, 9.0 min, or 10.0 min, etc.).

[0016] In the dry etching process of aluminum-based superconducting circuits, aluminum oxide particles often form due to aluminum corrosion when etching the aluminum metal layer. These aluminum oxide particles act as etching micromasks. When the etching of the underlying film layer continues, due to the masking effect, tall "pillars" closely attached to the sidewalls are left in the groove. In severe cases, the "pillars" can completely block the groove. To address this issue, this invention removes moisture from the sample surface by heating before dry etching the aluminum metal layer and immediately cleaning the etched sample with deionized water or oxalic acid and drying it after the aluminum metal layer etching is completed. This removes AlCl3 generated during the aluminum metal layer etching process and residual Cl ions, preventing the formation of insoluble and difficult-to-remove Al2O3 particles in the atmosphere after the sample is removed from the etching equipment. This avoids Al2O3 forming a micromask that affects the etching of the underlying film layer and prevents the formation of "pillars" that block the groove.

[0017] That is, by using the anomaly handling method provided by the present invention, the risk of morphological abnormalities and blockage after deep trench etching can be effectively avoided during the dry etching process of aluminum-based superconducting circuits, and it is easy to operate.

[0018] It should be noted that the present invention does not limit the shape of the slot described in step (1). For example, it can be a rectangle, a circle or other irregular shape.

[0019] Preferably, the step of immediately cleaning the etched sample with oxalic acid further includes rinsing with deionized water. It should be noted that the purpose of rinsing with deionized water in this step is to remove the oxalic acid from the sample surface.

[0020] Specifically, for example, immediately place the etched sample in a basket and rinse with deionized water for 0.5-10.0 min, or immediately immerse the etched sample directly in a beaker filled with deionized water for 0.5-10.0 min, then remove the sample and dry it; or immediately place the etched sample in a basket and immerse it in a beaker filled with oxalic acid for 0.5-10.0 min, then remove the sample, rinse with deionized water and dry it.

[0021] Preferably, the drying method includes drying with a nitrogen gun.

[0022] Preferably, the heating temperature in step (2) is 100-150℃, such as 100℃, 105℃, 110℃, 113℃, 115℃, 118℃, 120℃, 123℃, 125℃, 128℃, 130℃, 135℃, 140℃, 145℃, or 150℃, and the heating time is 2.0-8.0 min, such as 2.0 min, 2.5 min, 3.0 min, 3.5 min, 4.0 min, 4.5 min, 5.0 min, 5.5 min, 6.0 min, 6.5 min, 7.0 min, 7.5 min, or 8.0 min. Specifically, for example, the sample can be placed on a heating plate for heating.

[0023] Preferably, the multilayer aluminum metal layer in step (1) is at least 3 layers (e.g., 3, 4, 5 or 6 layers) of aluminum metal layer, and the multilayer dielectric layer in step (1) is at least 3 layers (e.g., 3, 4, 5 or 6 layers) of dielectric layer.

[0024] Preferably, the thickness of each aluminum metal layer in the multilayer aluminum metal layer in step (1) is independently 0.06-2.0 μm, for example 0.06 μm, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm or 2.0 μm.

[0025] Preferably, the thickness of each dielectric layer in the multilayer dielectric layer in step (1) is independently 0.5-5.0 μm, for example, 0.5 μm, 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.1 μm, 3.2 μm, 3.3 μm, 3.4 μm, 3.5 μm, 3.6 μm, 3.7 μm, 3.8 μm, 3.9 μm, 4.0 μm, 4.1 μm, 4.2 μm, 4.3 μm, 4.4 μm, 4.5 μm, 4.6 μm, 4.7 μm, 4.8 μm, 4.9 μm or 5.0 μm.

[0026] Preferably, the dielectric layer in step (1) includes a silicon oxide layer, such as a silicon monoxide layer or a silicon dioxide layer.

[0027] Preferably, the gas used in the dry etching step (2) includes Cl2 and / or BCl3.

[0028] Preferably, the dry etching in step (2) is performed in a metal etching apparatus. It should be noted that the metal etching apparatus is the conventional equipment used in the prior art for dry etching of metals.

[0029] Preferably, the gas used in the dry etching step (2) includes Cl2 and BCl3 with a flow ratio of (1.0-2.0):1.0 (e.g., 1.0:1.0, 1.1:1.0, 1.2:1.0, 1.5:1.0, 1.8:1.0 or 2.0:1.0, etc.).

[0030] Preferably, the gas used in the dry etching process in step (3) includes CF4.

[0031] Preferably, the dry etching in step (3) is performed in a dielectric etching apparatus. It should be noted that the dielectric etching apparatus is the conventionally used equipment for dry etching of dielectrics in the prior art.

[0032] Preferably, the removal of the residual photoresist layer in step (5) can be carried out by wet removal using organic solvents such as N-methylpyrrolidone (NMP), acetone, and isopropanol.

[0033] As a preferred embodiment of the present invention, the anomaly handling method includes the following steps:

[0034] (1) Provide samples:

[0035] A stacked structure comprising multiple aluminum metal layers and multiple dielectric layers is formed on one side of a substrate, wherein the aluminum metal layers and the dielectric layers are alternately arranged, and in the stacked structure, the dielectric layer is closest to the substrate and the aluminum metal layer is furthest from the substrate.

[0036] A photoresist layer is formed on the side of the stacked structure away from the substrate, and the photoresist layer is patterned. The patterned photoresist layer includes at least one groove to obtain a sample.

[0037] (2) Heat the sample at 100-150℃ for 2.0-8.0 min, and then use gas Cl2 and / or BCl3 to etch the aluminum metal layer exposed by the groove in step (1) to expose the dielectric layer. Then immediately rinse or wash the etched sample with deionized water for 0.5-10.0 min, or immediately wash the etched sample with oxalic acid for 0.5-10.0 min and rinse with deionized water, and blow dry.

[0038] (3) Use CF4 gas to etch the exposed dielectric layer through the trench;

[0039] (4) Repeat steps (2) and (3) in sequence until the exposed aluminum metal layer and dielectric layer are etched away to expose the substrate.

[0040] (5) Remove the residual photoresist layer.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] In this invention, during the dry etching process in aluminum-based superconducting circuits, moisture on the sample surface is removed by heating before the aluminum metal layer is etched, and the etched sample is immediately cleaned with deionized water or oxalic acid and dried after the aluminum metal layer etching is completed. This removes AlCl3 generated during the aluminum metal layer etching process and residual Cl ions, preventing the formation of insoluble and difficult-to-remove Al2O3 particles in the atmosphere after the sample is removed from the etching equipment. This also avoids Al2O3 forming a micromask that affects the etching of the underlying film layer, preventing "pillars" from blocking the trench. In other words, the anomaly handling method provided by this invention can effectively avoid the risks of morphological abnormalities and blockage after deep trench etching in aluminum-based superconducting circuits during dry etching, and is easy to operate. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the ideal structure of an aluminum-based superconducting circuit before etching.

[0044] Figure 2 A schematic diagram of the ideal structure of an aluminum-based superconducting circuit after etching.

[0045] Wherein, 1-substrate, 2-dielectric layer, 3-aluminum metal layer.

[0046] Figure 3 A flowchart of a dry etching method for an aluminum-based superconducting circuit provided in the prior art.

[0047] Figure 4 The top view FIB image of the final sample obtained by using the dry etching method for aluminum-based superconducting circuits provided in the prior art.

[0048] Figure 5 The final frontal FIB image of the sample obtained by using the dry etching method for aluminum-based superconducting circuits provided in the prior art;

[0049] Among them, 4-column.

[0050] Figure 6 This is a flowchart of an anomaly handling method for dry etching in an aluminum-based superconducting circuit, provided as an embodiment of the present invention.

[0051] Figure 7 for Figure 6 A cross-sectional view of the structure corresponding to step S11 in the provided method for handling anomalies in dry etching of an aluminum-based superconducting circuit.

[0052] Figure 8 for Figure 6 A cross-sectional view of the structure corresponding to step S12 in the provided method for handling anomalies in dry etching of an aluminum-based superconducting circuit.

[0053] Figure 9 for Figure 6 A cross-sectional view of the structure corresponding to step S13 in the provided method for handling anomalies in dry etching of an aluminum-based superconducting circuit.

[0054] Figure 10 for Figure 6 A cross-sectional view of the structure corresponding to step S14 in the provided method for handling anomalies in dry etching of an aluminum-based superconducting circuit.

[0055] Figure 11 for Figure 6 A cross-sectional view of the structure corresponding to step S15 in a dry etching anomaly handling method for an aluminum-based superconducting circuit.

[0056] Among them, 110 is the substrate, 210 is the SiO2 dielectric layer, 220 is the aluminum metal layer, 300 is the photoresist layer, and 400 is the groove.

[0057] Figure 12The FIB image of the final sample is obtained by using the dry etching anomaly handling method provided in the embodiment of the present invention in an aluminum-based superconducting circuit. Detailed Implementation

[0058] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0059] As mentioned in the background technology, the etching and grooving process in the fabrication of multilayer metal wiring in aluminum-based superconducting circuits is particularly complex. It requires precisely etching narrow trenches. Due to the large depth-to-width ratio and the complex film structure where the vertical direction of the trench involves three or more pairs of overlapping aluminum metal layers and dielectric layers, it involves aluminum metal layers and dielectric layers (such as silicon oxide SiO₂). x Multiple alternating etchings of the dielectric layer. When etching the aluminum metal layer, aluminum oxide particles often appear due to aluminum corrosion. These aluminum oxide particles act as etching micromasks. When the underlying film layer is etched, due to the masking effect, tall "pillars" that are close to the sidewalls are left in the trench. In severe cases, the "pillars" will completely block the trench.

[0060] Figure 3 Here is a flowchart of a dry etching method for an aluminum-based superconducting circuit provided in the prior art, for reference. Figure 3 The method includes: S1, providing a sample: forming a stacked structure comprising 3 aluminum metal layers and 3 dielectric layers (only 3 aluminum metal layers and 3 dielectric layers are provided as an example, wherein the dielectric layer is a SiO2 layer) on one side of a substrate, wherein the aluminum metal layers and the dielectric layers are alternately arranged, and in the stacked structure, the dielectric layer is closest to the substrate and the aluminum metal layer is furthest from the substrate; forming a photoresist layer on the side of the stacked structure furthest from the substrate, and patterning the photoresist layer, wherein the patterned photoresist layer includes a groove, to obtain a sample; S2, dry etching the exposed aluminum metal layer of the groove; S3, dry etching the exposed dielectric layer of the groove; S4, repeating steps S2 and S3 in sequence until both the exposed aluminum metal layer and the dielectric layer are etched away, exposing the substrate; S5, removing the remaining photoresist layer. Using this method, the top view FIB (Focused Ion Beam) image and the front view FIB image of the final sample are shown below. Figure 4 and Figure 5 As shown, the etched sample exhibits a high number of "pillars" that are tightly attached to the sidewalls.

[0061] Therefore, embodiments of the present invention provide a method for preventing the formation of "pillars" and thus avoiding the blockage of grooves during the dry etching process of aluminum-based superconducting circuits. Figure 6 This is a flowchart of an anomaly handling method for dry etching in an aluminum-based superconducting circuit provided by an embodiment of the present invention. (Refer to...) Figure 6 The methods include:

[0062] S11. Providing a sample: A stacked structure comprising three aluminum metal layers (each with a thickness of 1 μm) and three dielectric layers (SiO2 dielectric layers, each with a thickness of 4 μm) is formed on one side of a substrate. The aluminum metal layers and the dielectric layers are alternately arranged, and in the stacked structure, the dielectric layer is closest to the substrate, and the aluminum metal layer is furthest from the substrate. A photoresist layer is formed on the side of the stacked structure furthest from the substrate, and the photoresist layer is patterned. The patterned photoresist layer includes a groove, thus obtaining a sample.

[0063] Specifically, the substrate material can include silicon. Figure 7 for Figure 6 The structural cross-sectional view corresponding to step S11 in the provided method for handling anomalies in dry etching of an aluminum-based superconducting circuit is shown in the reference diagram. Figure 7 A stacked structure comprising three aluminum metal layers 220 and three SiO2 dielectric layers 210 is formed on one side of the substrate 110. The aluminum metal layers 220 and SiO2 dielectric layers 210 are alternately arranged. In the stacked structure, the number of aluminum metal layers 220 and SiO2 dielectric layers 210 is the same. The SiO2 dielectric layer 210 is closest to the substrate 110, and the aluminum metal layer 220 is furthest from the substrate 110. That is, the SiO2 dielectric layer 210 and the aluminum metal layer 220 are arranged in pairs. A photoresist layer 300 is formed on the side of the stacked structure away from the substrate 110, and the photoresist layer 300 is patterned. Specifically, the photoresist layer is patterned by exposure and development. The patterned photoresist layer 300 includes a groove 400, the shape of which is rectangular, to obtain the sample.

[0064] S12. Heat the sample at 120°C for 5 minutes, then use a flow ratio of 2:1 Cl2 and BCl3 to etch the exposed aluminum metal layer through the groove, exposing the dielectric layer. Immediately rinse the etched sample with deionized water for 3 minutes and then blow dry.

[0065] Specifically, Figure 8 for Figure 6 The structural cross-sectional view corresponding to step S12 in the provided method for handling anomalies in dry etching of an aluminum-based superconducting circuit is shown in the reference diagram. Figure 8The sample was placed on a heating plate and heated at 120°C for 5 minutes. Then, the exposed aluminum metal layer 220 was etched in a metal etching device using gases Cl2 and BCl3 with a flow ratio of 2:1, exposing the SiO2 dielectric layer 210. The etched sample was then immediately placed in a basket and rinsed with deionized water for 3 minutes. The sample was then removed and dried with a nitrogen gun.

[0066] S13. The exposed dielectric layer is etched using CF4 gas.

[0067] Specifically, Figure 9 for Figure 6 The structural cross-sectional view corresponding to step S13 in the provided method for handling anomalies in dry etching of an aluminum-based superconducting circuit is shown in the reference diagram. Figure 9 The SiO2 dielectric layer 210 exposed by trenching is etched using CF4 gas in a dielectric etching apparatus.

[0068] S14. Repeat steps S12 and S13 in sequence until the exposed aluminum metal layer and dielectric layer are etched away, exposing the substrate.

[0069] Specifically, Figure 10 for Figure 6 The structural cross-sectional view corresponding to step S14 in the provided method for handling anomalies in dry etching of an aluminum-based superconducting circuit is shown in the reference diagram. Figure 10 Steps S12 and S13 are repeated sequentially until the exposed aluminum metal layer 220 and SiO2 dielectric layer 210 are etched away, exposing the substrate 110.

[0070] S15. Remove the residual photoresist layer.

[0071] Specifically, Figure 11 for Figure 6 The structural cross-sectional view corresponding to step S15 in the provided method for handling anomalies in dry etching of an aluminum-based superconducting circuit is shown in the reference diagram. Figure 11 The residual photoresist layer was removed using NMP wet process, leaving the substrate and stacked structure.

[0072] Figure 12 The FIB image of the final sample obtained by using the dry etching anomaly treatment method in aluminum-based superconducting circuits provided in the above embodiments of the present invention shows that no "pillars" appear on the sidewall of the final sample obtained by using the dry etching anomaly treatment method in aluminum-based superconducting circuits provided in the present invention.

[0073] That is, in this invention, during dry etching in aluminum-based superconducting circuits, an unusual treatment method is adopted: heating to remove moisture from the sample surface before dry etching the aluminum metal layer, and immediately cleaning the etched sample with deionized water or oxalic acid and drying it after the aluminum metal layer etching is completed. This removes AlCl3 generated during the aluminum metal layer etching process and residual Cl ions, preventing the formation of insoluble and difficult-to-remove Al2O3 particles in the atmosphere after the sample is removed from the etching equipment. This avoids Al2O3 forming a micromask that affects the etching of the underlying film layer, thereby avoiding the formation of "pillars" and the risk of clogging the trench.

[0074] The applicant declares that this invention illustrates the method for handling abnormalities in dry etching of aluminum-based superconducting circuits through the above embodiments, but this invention is not limited to the above embodiments, that is, it does not mean that this invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials used in this invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

Claims

1. A method for handling anomalies in dry etching in aluminum-based superconducting circuits, characterized in that, The exception handling method includes the following steps: (1) Provide samples: A stacked structure comprising multiple aluminum metal layers and multiple dielectric layers is formed on one side of a substrate, wherein the aluminum metal layers and the dielectric layers are alternately arranged, and in the stacked structure, the dielectric layer is closest to the substrate and the aluminum metal layer is furthest from the substrate. A photoresist layer is formed on the side of the stacked structure away from the substrate, and the photoresist layer is patterned. The patterned photoresist layer includes at least one groove to obtain a sample. (2) Heat the sample and then use dry etching to etch the aluminum metal layer exposed by the groove in step (1), expose the dielectric layer by the groove, and then immediately clean the etched sample with deionized water or oxalic acid and blow it dry. (3) The exposed dielectric layer in the trench is etched using a dry etching method; (4) Repeat steps (2) and (3) in sequence until the exposed aluminum metal layer and dielectric layer are etched away to expose the substrate; (5) Remove the residual photoresist layer; Step (2) involves immediately cleaning the etched sample with deionized water or oxalic acid, specifically including the following steps: Rinse or wash the etched sample immediately with deionized water for 0.5-10.0 min, or immediately wash the etched sample with oxalic acid for 0.5-10.0 min.

2. The anomaly handling method according to claim 1, characterized in that, The heating temperature in step (2) is 100-150℃ and the heating time is 2.0-8.0 min.

3. The anomaly handling method according to claim 1, characterized in that, The multilayer aluminum metal layer in step (1) is at least 3 aluminum metal layers, and the multilayer dielectric layer in step (1) is at least 3 dielectric layers.

4. The anomaly handling method according to claim 1, characterized in that, In step (1), the thickness of each aluminum metal layer in the multilayer aluminum metal layer is independently 0.06-2.0 μm.

5. The anomaly handling method according to claim 1, characterized in that, In step (1), the thickness of each dielectric layer in the multilayer dielectric layer is independently 0.5-5.0 μm.

6. The anomaly handling method according to claim 1, characterized in that, The dielectric layer in step (1) includes a silicon oxide layer.

7. The anomaly handling method according to claim 1, characterized in that, The gas used in the dry etching process in step (2) includes Cl2 and / or BCl3.

8. The anomaly handling method according to claim 1, characterized in that, The gas used in the dry etching process in step (3) includes CF4.

9. The anomaly handling method according to any one of claims 1-8, characterized in that, The exception handling method includes the following steps: (1) Provide samples: A stacked structure comprising multiple aluminum metal layers and multiple dielectric layers is formed on one side of a substrate, wherein the aluminum metal layers and the dielectric layers are alternately arranged, and in the stacked structure, the dielectric layer is closest to the substrate and the aluminum metal layer is furthest from the substrate. A photoresist layer is formed on the side of the stacked structure away from the substrate, and the photoresist layer is patterned. The patterned photoresist layer includes at least one groove to obtain a sample. (2) Heat the sample at 100-150℃ for 2.0-8.0 min, and then use gas Cl2 and / or BCl3 to etch the aluminum metal layer exposed by the groove in step (1) to expose the dielectric layer. Then immediately rinse or wash the etched sample with deionized water for 0.5-10.0 min, or immediately wash the etched sample with oxalic acid for 0.5-10.0 min and rinse with deionized water, and blow dry. (3) Use CF4 gas to etch the exposed dielectric layer through the trench; (4) Repeat steps (2) and (3) in sequence until the exposed aluminum metal layer and dielectric layer are etched away to expose the substrate; (5) Remove the residual photoresist layer.

Images