Etching method for improving high aspect ratio loading effect and semiconductor structure

Abstract

This application discloses an etching method and semiconductor structure for improving the high aspect ratio loading effect, comprising: using a plasma etching process with periodic cyclic steps including a deposition step, a first etching step, and a second etching step to simultaneously form a first etched structure and a second etched structure on a substrate, wherein the width of the first etched structure is greater than the width of the second etched structure; during the deposition step, ion-assisted deposition is performed using a first auxiliary gas to increase the density of the polymer layer at the bottom of the first etched structure during formation; during the first etching step, ion-assisted etching is performed using a second auxiliary gas to suppress over-etching of the polymer layer at the bottom of the first etched structure during formation, thereby increasing the effective etching time of the substrate material below the bottom of the second etched structure during the second etching step, and improving the difference in final etching depth between the first etched structure and the second etched structure with different widths.

Description

Technical Field

[0001] This application relates to the field of semiconductor processing technology, and in particular to an etching method and semiconductor structure for improving high aspect ratio loading effects. Background Technology

[0002] With the rapid development of key components such as inertial sensors (such as accelerometers and gyroscopes) and pressure sensors in microelectromechanical systems towards higher sensitivity and multi-functional integration, special structural layouts with both wide and narrow slots are becoming increasingly common. This places extremely stringent requirements on the depth uniformity, morphological consistency, and etching synchronization across patterned regions in deep silicon etching.

[0003] In the manufacturing process of the aforementioned devices, it is often necessary to simultaneously form multiple high aspect ratio etched structures (such as deep trenches or deep holes) with different dimensions on the same wafer. Due to the Knudsen diffusion effect, it is more difficult for reactive gases and ions to enter the bottom of narrow trenches, resulting in a significantly lower effective etching rate for narrow trenches than for wide trenches. This leads to an increasingly prominent aspect ratio-dependent etching (ARDE) effect, which has become a major process challenge restricting the large-scale and stable manufacturing of the aforementioned devices.

[0004] Currently, traditional methods for improving ARDE typically involve using SOI wafers as etching stop layers. However, this approach is prone to problems such as notching, residual stress, and high costs in practical applications, and it does not effectively eliminate ARDE. Therefore, a new optimized etching method is needed that can improve ARDE while meeting high-performance requirements. Summary of the Invention

[0005] The purpose of this application is to overcome the aforementioned problems in the prior art and to provide an etching method and semiconductor structure that improves the high aspect ratio loading effect.

[0006] To achieve the above objectives, the technical solution of this application is as follows: According to a first aspect of this application, embodiments of this application provide an etching method for improving high aspect ratio loading effects, comprising: Provide substrate; The surface of the substrate is etched using a plasma etching process that includes a deposition step, a first etching step, and a second etching step in sequence, thereby simultaneously forming a first etched structure and a second etched structure on the substrate, wherein the width of the first etched structure is greater than the width of the second etched structure. In the deposition step, when depositing polymer layers on the first inner wall of the first etched structure and the second inner wall of the second etched structure, ion-assisted deposition is performed using a first auxiliary gas, and the high aspect ratio loading effect is utilized to make the density of the polymer layer formed on the bottom of the first inner wall greater than the density of the polymer layer formed on the bottom of the second inner wall. When performing the first etching step to etch and remove the polymer layers on the bottom of the first inner wall and the bottom of the second inner wall, ion-assisted etching is performed using a second auxiliary gas to weaken the effect of the high aspect ratio loading effect. This ensures that when the polymer layer on the bottom of the second inner wall is completely removed, the polymer layer on the bottom of the first inner wall remains. This allows the effective etching time for the substrate material below the bottom of the second inner wall to be longer than the effective etching time for the substrate material below the bottom of the first inner wall when performing the second etching step to etch the substrate material below the bottom of the first inner wall. This results in the bottom of the final etched structure being flush with the bottom of the second etched structure.

[0007] In some embodiments, by performing the deposition step under a first pressure and a first bias power, the ion bombardment effect of the first auxiliary gas ions on the polymer layer formed on the bottom of the first inner wall is stronger than the ion bombardment effect on the polymer layer formed on the bottom of the second inner wall, thereby compacting the polymer layer formed on the bottom of the first inner wall, resulting in a higher density of the polymer layer formed on the bottom of the first inner wall than the polymer layer formed on the bottom of the second inner wall; by performing the first etching step under a second pressure and a second bias power, the auxiliary etching capability of the second auxiliary gas ions on the polymer layer on the bottom of the second inner wall is improved, promoting the rapid removal of the polymer layer on the bottom of the second inner wall, thereby achieving that when performing the second etching step, the effective etching time for the substrate material below the bottom of the second inner wall is greater than the effective etching time for the substrate material below the bottom of the first inner wall, the first pressure is greater than the second pressure, and the first bias power is greater than zero and less than the second bias power.

[0008] In some embodiments, during the deposition step, a high aspect ratio loading effect is also utilized such that the thickness of the polymer layer formed on the bottom of the first inner wall is greater than the thickness of the polymer layer formed on the bottom of the second inner wall.

[0009] In some embodiments, the second etching step is performed under a third pressure and a third bias power to reduce the etching rate of the remaining polymer layer on the bottom of the first inner wall, thereby further increasing the effective etching time for the substrate material below the bottom of the second inner wall; the third pressure is greater than the second pressure, and the third bias power is less than the first bias power.

[0010] In some embodiments, the first pressure is 30 mTorr to 300 mTorr, and the first bias power is 10 W to 50 W.

[0011] In some embodiments, the second pressure is 10 mTorr to 50 mTorr, and the second bias power is 200 W to 500 W.

[0012] In some embodiments, the third pressure is 30 mTorr to 300 mTorr, and the third bias power is 0 W to 10 W.

[0013] In some embodiments, the first bias power is applied in a pulsed manner.

[0014] In some embodiments, the second bias power is applied in a pulsed manner.

[0015] In some embodiments, when performing the deposition step, a deposition gas is used to deposit polymer layers on the first inner wall of the first etched structure and the second inner wall of the second etched structure, and the first auxiliary gas is added to the deposition gas to perform ion-assisted deposition. The deposition gas includes a fluorocarbon gas, and the first auxiliary gas includes a first non-reactive gas. When performing the first etching step, a first etching gas is used to remove the polymer layers on the bottom of the first inner wall and the bottom of the second inner wall, and the second auxiliary gas is added to the first etching gas to improve the etching capability of the polymer layers on the bottom of the second inner wall. The first etching gas includes a second non-reactive gas, and the second auxiliary gas includes an oxidizing gas. When performing the second etching step, a second etching gas is used to etch the substrate material below the bottom of the first inner wall and the bottom of the second inner wall. The second etching gas includes a fluorine-containing gas.

[0016] In some embodiments, the fluorocarbon gas includes C4F8.

[0017] In some embodiments, the first non-reactive gas includes at least one of an inert gas and nitrogen.

[0018] In some embodiments, the second non-reactive gas includes an inert gas.

[0019] In some embodiments, the oxidizing gas includes oxygen.

[0020] In some embodiments, the flow rate of the second auxiliary gas is greater than the flow rate of the first etching gas.

[0021] In some embodiments, the fluorine-containing gas includes SF6.

[0022] In some embodiments, when performing the second etching step, for the first etched structure being formed, the remaining polymer layer at the bottom of the first inner wall is first etched away, and then the substrate material below the bottom of the first inner wall is etched. For the second etched structure being formed, the substrate material exposed below the bottom of the second inner wall is directly etched.

[0023] In some embodiments, the method further includes an atmosphere displacement step; the atmosphere displacement step is performed between any two adjacent steps in a periodic cycle of the deposition step, the first etching step, and the second etching step, for displacing the atmosphere in the first etched structure and the second etched structure being formed by introducing a displacement gas.

[0024] In some embodiments, the replacement gas includes at least one of an inert gas and nitrogen.

[0025] According to a second aspect of this application, embodiments of this application also provide a semiconductor structure, the semiconductor structure including a substrate and a first etched structure and a second etched structure simultaneously formed on the substrate, the semiconductor structure being obtained using an etching method for improving high aspect ratio loading effects as provided in any of the embodiments of the first aspect above.

[0026] The embodiments of this application may have, or at least have, the following advantages: (1) To address the aspect ratio dependent etching (ARDE) effect that occurs during high aspect ratio etching, by coordinating the deposition step, the first etching step and the second etching step in the etching process, it is possible to suppress the over-etching of the polymer layer at the bottom of the first etched structure with a wider width during formation, while promoting the rapid removal of the polymer layer at the bottom of the second etched structure with a narrower width during formation, and adjusting the breakthrough time difference between the polymer layers at the bottom of the first etched structure and the second etched structure during formation. Thus, through the combination of multiple process optimizations, the difference in the final etching depth between the first etched structure and the second etched structure with different widths is improved.

[0027] (2) By introducing a controllable bias power (first bias power) and a first auxiliary gas in the deposition step to deposit a polymer layer, the thin film properties (density) of the polymer layer can be controlled by ion-assisted deposition, so that a more stable and etch-resistant polymer layer can be formed on the bottom of the first etched structure. When performing the first etching step, the over-etching of the polymer layer on the bottom of the first etched structure can be suppressed. Thus, when performing the second etching step, more effective etching time can be obtained for etching the substrate material below the bottom of the second etched structure, which is beneficial to eliminating the difference in etching depth between the first etched structure and the second etched structure in each periodic cycle.

[0028] (3) By introducing an oxidizing gas (second auxiliary gas) in the first etching step to assist in the removal of the polymer layer, and combined with low-pressure, high-directional ion bombardment conditions (second pressure, second bias power), the rapid removal of the polymer layer at the bottom of the second etched structure can be promoted, so that the breakthrough time of the polymer layer at the bottom of the second etched structure is advanced compared with the traditional process. Thus, when performing the second etching step, the effective etching time for etching the substrate material below the bottom of the second etched structure can be increased.

[0029] (4) By setting an atmosphere replacement step between any two adjacent steps of the deposition step, the first etching step and the second etching step in the periodic cycle, the atmosphere in the first etched structure and the second etched structure in the formation can be replaced, which can effectively reduce the cross interference caused by residual process gas and by-products to adjacent steps.

[0030] This application improves upon the problem of traditional high aspect ratio etching processes struggling to simultaneously address wide trenches (e.g., the first etched structure) and narrow trenches (e.g., the second etched structure) by synergistically designing the deposition, first etching, second etching, and atmosphere replacement steps. In each cycle, it can suppress over-etching at the bottom of wide trenches while promoting the removal of the polymer layer at the bottom of narrow trenches, reducing the etching depth difference between wide and narrow trenches, and improving the quality of residue at the bottom of narrow trenches, trench closure, and sidewall morphology. This enhances the processing consistency of high aspect ratio silicon structures such as MEMS and TSVs.

[0031] Other advantages of this application will be described in the following detailed description. Attached Figure Description

[0032] Figure 1 This is a flowchart of an etching method for improving high aspect ratio loading effects, provided as a preferred embodiment of this application.

[0033] Figure 2 This is a schematic diagram of a preferred embodiment of the present application after forming a first intermediate etching structure and a second intermediate etching structure on the surface of a substrate.

[0034] Figure 3 This is a schematic diagram of a polymer layer deposited on the inner wall of a first intermediate etched structure and a second intermediate etched structure, according to a preferred embodiment of this application.

[0035] Figure 4 This is a schematic diagram of the polymer layer on the bottom of the first intermediate etched structure and the second intermediate etched structure after etching removal, provided as a preferred embodiment of this application.

[0036] Figure 5This is a schematic diagram illustrating the principle of providing more effective etching time for the substrate material below the bottom of the second intermediate etching structure, according to a preferred embodiment of this application.

[0037] Figure 6 This is a schematic diagram illustrating an increase in etching depth after etching the substrate material below the bottom of the first intermediate etching structure and the second intermediate etching structure, according to a preferred embodiment of this application.

[0038] Figure 7 This is a schematic diagram of a preferred embodiment of the present application after a polymer layer is redeposited on the inner walls of a first intermediate etched structure and a second intermediate etched structure with increased etching depth.

[0039] Figure 8 This is a schematic diagram of a preferred embodiment of the present application after etching away the polymer layer redeposited on the bottom of the first intermediate etched structure and the second intermediate etched structure.

[0040] Figure 9 This is a schematic diagram illustrating a preferred embodiment of the present application, in which the polymer layer redeposited on the bottom of the first intermediate etched structure and the second intermediate etched structure is etched away, and then the substrate material below them is etched to further increase the etching depth.

[0041] Figure 10 This is a schematic diagram of a preferred embodiment of the present application after forming a first etched structure and a second etched structure on the surface of a substrate.

[0042] In the figure: 10. Substrate; 11. First intermediate etched structure; 12. Second intermediate etched structure; 13. Mask layer; 14. Polymer layer; 15. First etched structure; 16. Second etched structure. Detailed Implementation

[0043] To address the issues arising during deep silicon etching of MEMS wide and narrow trench parallel structures, or traditional high aspect ratio etching structures, differences in reactant transport, bottom polymer layer removal, ion arrival capability, and byproduct removal capability between trenches of different widths lead to inconsistent etching depths, residue at the bottom of narrow trenches, trench narrowing, over-etching of wide trenches, and exacerbated ARDE effects. This application provides an etching method to improve the high aspect ratio loading effect, including: Provide substrate; The surface of the substrate is etched using a plasma etching process that includes a deposition step, a first etching step, and a second etching step in sequence, thereby simultaneously forming a first etched structure and a second etched structure on the substrate, wherein the width of the first etched structure is greater than the width of the second etched structure. In the deposition step, when depositing polymer layers on the first inner wall of the first etched structure and the second inner wall of the second etched structure, ion-assisted deposition is performed using a first auxiliary gas, and the high aspect ratio loading effect is utilized to make the density of the polymer layer formed on the bottom of the first inner wall greater than the density of the polymer layer formed on the bottom of the second inner wall. When performing the first etching step to etch and remove the polymer layers on the bottom of the first inner wall and the bottom of the second inner wall, ion-assisted etching is performed using a second auxiliary gas to weaken the effect of the high aspect ratio loading effect. This ensures that when the polymer layer on the bottom of the second inner wall is completely removed, the polymer layer on the bottom of the first inner wall remains. This allows the effective etching time for the substrate material below the bottom of the second inner wall to be longer than the effective etching time for the substrate material below the bottom of the first inner wall when performing the second etching step to etch the substrate material below the bottom of the first inner wall. This results in the bottom of the final etched structure being flush with the bottom of the second etched structure.

[0044] This application addresses the aspect ratio dependent etching (ARDE) effect that occurs during high aspect ratio etching. By synergistically controlling the deposition step, the first etching step, and the second etching step in the etching process, it can suppress over-etching of the polymer layer at the bottom of the wider first etched structure while promoting the rapid removal of the polymer layer at the bottom of the narrower second etched structure. It also adjusts the breakthrough time difference between the bottom polymer layers of the first and second etched structures, thereby improving the difference in final etching depth between the first and second etched structures with different widths through multi-process optimization.

[0045] This application also provides a semiconductor structure, which includes a substrate and a first etched structure and a second etched structure simultaneously formed on the substrate. The semiconductor structure is obtained using an etching method for improving high aspect ratio loading effects as provided in any of the embodiments of the first aspect above.

[0046] The specific embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0047] refer to Figure 1 In a first aspect, embodiments of this application provide an etching method for improving the high aspect ratio loading effect, which may sequentially include the following steps: Step S11: Provide a substrate.

[0048] refer to Figure 2In some embodiments, a substrate 10 may be used to etch the surface of the substrate 10 using a plasma etching process, simultaneously forming a first etched structure and a second etched structure with a high aspect ratio on the substrate 10 to obtain the desired semiconductor structure. The width of the first etched structure is greater than the width of the second etched structure.

[0049] The etching process includes multiple cyclic steps, sequentially consisting of a deposition step, a first etching step, and a second etching step. The deposition step deposits polymer layers on the inner walls (first inner wall) of the forming first etched structure and the inner walls (second inner wall) of the forming second etched structure. The first etching step removes the polymer layers located at the bottom of the first inner wall and the bottom of the second inner wall, allowing the second etching step to further etch the substrate material below the bottom of the first and second inner walls, thereby increasing the etching depth of both the forming first and second etched structures. By cyclically executing the deposition step, the first etching step, and the second etching step, first and second etched structures with different widths can ultimately be formed simultaneously on the substrate 10.

[0050] The first and second etched structures may include deep trenches, deep vias, or through vias. For example, the first and second etched structures may be deep trenches, i.e., the first etched structure is a wide trench and the second etched structure is a narrow trench.

[0051] In some embodiments, substrate 10 may be a silicon substrate, such as a silicon wafer. However, it is not limited to this.

[0052] Step S12: Form a first intermediate etching structure and a second intermediate etching structure on the surface of the substrate, wherein the width of the first intermediate etching structure is greater than the width of the second intermediate etching structure.

[0053] refer to Figure 2 In some embodiments, a mask layer 13 may be formed on the surface of the substrate 10, and a first intermediate etching structure 11 and a second intermediate etching structure 12 may be simultaneously formed on the exposed surface of the substrate 10 by patterning the mask layer 13. The top of the first intermediate etching structure 11 and the top of the second intermediate etching structure 12 have openings. The first intermediate etching structure 11 is used to form a first etching structure, and the second intermediate etching structure 12 is used to form a second etching structure. In other words, the first intermediate etching structure 11 is the first etching structure under formation, and the second intermediate etching structure 12 is the second etching structure under formation.

[0054] In some embodiments, the mask layer 13 may include a photoresist layer, etc. The photoresist layer can be photolithographically etched to simultaneously form a first intermediate etching structure 11 and a second intermediate etching structure 12 on the exposed surface of the substrate 10.

[0055] The first intermediate etching structure 11 has a first width L1, and the second intermediate etching structure 12 has a second width L2, wherein the first width L1 is greater than the second width L2. That is, the trench width of the first intermediate etching structure 11 is greater than the trench width of the second intermediate etching structure 12, so that the trench width of the finally formed first etching structure is greater than the trench width of the second etching structure.

[0056] Step S13: Deposit polymer layers on the inner walls of the first intermediate etched structure and the second intermediate etched structure, and make the density of the polymer layer at the bottom of the first intermediate etched structure greater than the density of the polymer layer at the bottom of the second intermediate etched structure.

[0057] refer to Figure 3 In some embodiments, a deposition step is performed in the first cyclic step of the etching process, and a polymer layer 14 (mainly a fluorocarbon polymer material) is deposited as a passivation layer on the inner wall (first inner wall) of the first intermediate etched structure 11 and the inner wall (second inner wall) of the second intermediate etched structure 12 using a deposition gas to protect the sidewalls of the etched structure during etching. That is, a polymer layer 14 is deposited on the first inner wall of the first etched structure in formation and the second inner wall of the second etched structure in formation.

[0058] Furthermore, during the deposition step, a first auxiliary gas is added to the deposition gas to perform ion-assisted deposition during the deposition of the polymer layer 14, thereby controlling the film properties of the polymer layer 14.

[0059] In some embodiments, a plasma formed by a deposition gas with a first auxiliary gas is used, and the deposition step is performed under a first pressure and a controllable first bias power (the first bias power needs to be greater than zero). Utilizing the high aspect ratio loading effect (aspect ratio dependent etching (ARDE) effect), the ion bombardment effect of the first auxiliary gas on the polymer layer 14 formed on the bottom of the first inner wall of the first intermediate etched structure 11 is stronger than the ion bombardment effect on the polymer layer 14 formed on the bottom of the second inner wall of the second intermediate etched structure 12. Therefore, the polymer layer 14 formed on the bottom of the first intermediate etched structure 11 is compacted, while the effect on the polymer layer 14 formed on the bottom of the second intermediate etched structure 12 is weaker. This results in a higher density of the polymer layer 14 formed on the bottom of the first intermediate etched structure 11 than the polymer layer 14 formed on the bottom of the second intermediate etched structure 12.

[0060] Furthermore, due to the high aspect ratio loading effect, the thickness of the polymer layer 14 formed on the bottom of the first intermediate etching structure 11 will be greater than the thickness of the polymer layer 14 formed on the bottom of the second intermediate etching structure 12.

[0061] In some embodiments, the first bias power can be applied in a pulsed manner to achieve a better compaction effect on the polymer layer 14 at the bottom of the first intermediate etched structure 11, while avoiding a significant increase in the density of the polymer layer 14 at the bottom of the second intermediate etched structure 12 (the ion bombardment effect on the bottom of the narrower second intermediate etched structure 12 is already significantly weaker than that on the first intermediate etched structure 11. By using an intermittent pulsed manner, the ion bombardment effect on the polymer layer 14 at the bottom of the second intermediate etched structure 12 can be further weakened, and the density variation of the polymer layer 14 at the bottom of the second intermediate etched structure 12 can be further reduced, so as to maximize the difference in density between the polymer layer 14 at the bottom of the first intermediate etched structure 11 and the polymer layer 14 at the bottom of the second intermediate etched structure 12).

[0062] In some embodiments, the deposition gas may include a fluorocarbon gas. For example, the deposition gas may include fluorocarbon gases such as C4F8. However, it is not limited to this.

[0063] In some embodiments, the first auxiliary gas may include a first non-reactive gas. The first non-reactive gas may include at least one of an inert gas (e.g., Ar) and nitrogen.

[0064] In some embodiments, the flow rate of the deposition gas is 10 sccm to 1000 sccm. For example, the flow rate of the deposition gas may be 10 sccm, 20 sccm, 40 sccm, 50 sccm, 100 sccm, 200 sccm, 500 sccm, 800 sccm or 1000 sccm, or any value between any two of the aforementioned flow rate values.

[0065] In some embodiments, the flow rate of the first auxiliary gas is 5 sccm to 500 sccm. For example, the flow rate of the first auxiliary gas may be 5 sccm, 10 sccm, 50 sccm, 80 sccm, 100 sccm, 200 sccm, 300 sccm or 500 sccm, or any value between any two of the aforementioned flow rate values.

[0066] In some embodiments, the first pressure is 30 mTorr to 300 mTorr. For example, the first pressure may be 30 mTorr, 50 mTorr, 80 mTorr, 100 mTorr, 150 mTorr, 200 mTorr, 250 mTorr or 300 mTorr, or any value between any two of the aforementioned pressure values.

[0067] In some embodiments, the first bias power is 10W to 50W. For example, the first bias power may be 10W, 15W, 20W, 25W, 30W, 35W, 40W, 45W or 50W, or any value between any two of the aforementioned power values.

[0068] By introducing a controllable bias power (first bias power) and a first auxiliary gas during the deposition step, the thin film properties (density) of the polymer layer 14 can be controlled through ion-assisted deposition. This allows a thicker, more stable, and more etch-resistant polymer layer 14 to be formed on the bottom of the first etched structure (first intermediate etched structure 11). Consequently, the removal of the polymer layer 14 on the bottom of the first etched structure can be slowed down during the subsequent first etch step, suppressing over-etching of the polymer layer 14 on the bottom of the first etched structure. This allows for more effective etching time to be allocated for etching the substrate material below the bottom of the second etched structure (second intermediate etched structure 12) during the second etch step. This helps to eliminate the effects of high aspect ratio loading and reduce the difference in etching depth between the first and second etched structures in each cycle.

[0069] Step S14: Etch away the polymer layer on the bottom of the first intermediate etched structure and the second intermediate etched structure, and completely remove the polymer layer on the bottom of the second intermediate etched structure, while the polymer layer on the bottom of the first intermediate etched structure remains.

[0070] refer to Figure 4 In some embodiments, a first etching step is performed in the first cyclic step of the etching process, and a first etching gas is used to etch and remove the polymer layer 14 on the bottom of the first inner wall of the first intermediate etched structure 11 and the polymer layer 14 on the bottom of the second inner wall of the second intermediate etched structure 12. That is, the polymer layer 14 on the bottom of the first inner wall of the first etched structure and the polymer layer 14 on the bottom of the second inner wall of the second etched structure are etched and removed.

[0071] Furthermore, during the first etching step, a second auxiliary gas is added to the first etching gas to perform ion-assisted etching when removing the polymer layer 14, thereby reducing the effect of the high aspect ratio loading effect. The purpose is to adjust the original time difference between the breakthrough time of the polymer layer 14 at the bottom of the second intermediate etching structure 12 and the breakthrough time of the polymer layer 14 at the bottom of the first intermediate etching structure 11, thereby increasing the effective etching time for subsequent etching of the substrate material below the bottom of the second intermediate etching structure 12, and avoiding differences in etching depth between the second intermediate etching structure 12 and the first intermediate etching structure 11 in each periodic cycle.

[0072] In some embodiments, a plasma formed from a first etching gas with a second auxiliary gas is used, and the first etching step is performed under a second pressure and a second bias power. The low pressure of the second pressure and the highly directional ion bombardment generated by the higher second bias power enhance the ion-assisted etching capability of the second auxiliary gas on the polymer layer 14 at the bottom of the second intermediate etched structure 12, promoting rapid removal of the polymer layer 14 and shortening the breakthrough time of the polymer layer 14 at the bottom of the second intermediate etched structure 12. This ensures that when the polymer layer 14 at the bottom of the second intermediate etched structure 12 is completely removed, the polymer layer 14 at the bottom of the first intermediate etched structure 11 remains, thus suppressing over-etching of the polymer layer 14 at the bottom of the first intermediate etched structure 11 and allowing the first etching step to be terminated. This allows for a longer effective etching time for the substrate material below the bottom of the second intermediate etch structure 12 than for the substrate material below the bottom of the first intermediate etch structure 11 during the subsequent second etching step. This increases the effective etching time for the substrate material below the bottom of the second intermediate etch structure 12, which helps to eliminate the effects of the high aspect ratio loading effect. Therefore, it can reduce the difference in etching depth between the first and second etch structures in each periodic cycle.

[0073] In some embodiments, the second pressure is less than the first pressure and the second bias power is greater than the first bias power, so as to form low-pressure, high-directional ion bombardment conditions during the first etching step, promote the removal of the polymer layer 14 at the bottom of the second intermediate etched structure 12, and advance the etching breakthrough time of the polymer layer 14 at the bottom of the second intermediate etched structure 12 compared with conventional processes, thereby increasing the effective etching time when etching the substrate material at the bottom of the second intermediate etched structure 12.

[0074] In some embodiments, the second bias power can be applied in a pulsed manner to effectively etch and remove the polymer layer 14 on the bottom of the second intermediate etch structure 12, while slowing down the etching rate of the polymer layer 14 on the bottom of the first intermediate etch structure 11 as much as possible, thereby allowing more effective etching time for etching the substrate material below the bottom of the second intermediate etch structure 12.

[0075] In some embodiments, the first etching gas includes a second non-reactive gas. The second non-reactive gas may include an inert gas (e.g., Ar).

[0076] In some embodiments, the second auxiliary gas includes an oxidizing gas. The oxidizing gas may include oxygen, etc.

[0077] In some embodiments, the flow rate of the second auxiliary gas is greater than the flow rate of the first etching gas.

[0078] In some embodiments, the ratio of the flow rate of the second auxiliary gas to the flow rate of the first etching gas is 1.1 to 2. For example, the ratio of the flow rate of the second auxiliary gas to the flow rate of the first etching gas may be 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2, etc. However, it is not limited to this.

[0079] In some embodiments, the flow rate of the first etching gas is 5 sccm to 200 sccm. For example, the flow rate of the first etching gas may be 5 sccm, 10 sccm, 30 sccm, 50 sccm, 80 sccm, 100 sccm, 150 sccm, 180 sccm or 200 sccm, or any value between any two of the aforementioned flow rate values.

[0080] In some embodiments, the flow rate of the second auxiliary gas is 6 sccm to 400 sccm. For example, the flow rate of the second auxiliary gas may be 6 sccm, 8 sccm, 10 sccm, 50 sccm, 100 sccm, 200 sccm, 300 sccm or 400 sccm, or any value between any two of the aforementioned flow rate values.

[0081] In some embodiments, the second pressure is 10 mTorr to 50 mTorr. For example, the second pressure may be 10 mTorr, 15 mTorr, 20 mTorr, 25 mTorr, 30 mTorr, 35 mTorr, 40 mTorr, 45 mTorr or 50 mTorr, or any value between any two of the aforementioned pressure values.

[0082] In some embodiments, the second bias power is 200W to 500W. For example, the second bias power may be 200W, 215W, 230W, 250W, 300W, 350W, 400W, 450W or 500W, or any value between any two of the aforementioned power values.

[0083] By introducing an oxidizing gas (second auxiliary gas) in the first etching step to assist in the removal of the polymer layer 14, and combining it with low-pressure, high-directional ion bombardment conditions (second pressure, second bias power), the rapid removal of the polymer layer 14 at the bottom of the second intermediate etched structure 12 can be promoted, so that the breakthrough time of the polymer layer 14 at the bottom of the second intermediate etched structure 12 is advanced compared with the conventional process. Thus, when the second etching step is performed in the subsequent step, the effective etching time for etching the substrate material below the bottom of the second intermediate etched structure 12 can be increased.

[0084] Step S15: Etch the substrate material below the bottom of the first intermediate etching structure and the second intermediate etching structure to increase the etching depth of the first intermediate etching structure and the bottom of the second intermediate etching structure are flush.

[0085] In some embodiments, a second etching step is performed in the first periodic cycle of the etching process, and a second etching gas is used to etch the substrate material below the bottom of the first intermediate etched structure 11 and the substrate material below the bottom of the second intermediate etched structure 12. That is, the substrate material below the bottom of the first inner wall of the first etched structure and the substrate material below the bottom of the second inner wall of the second etched structure are etched.

[0086] In this process, since the polymer layer 14 on the bottom of the second intermediate etched structure 12 has been completely etched away at the end of the first etching step, the substrate material below the bottom of the second intermediate etched structure 12 is exposed. Meanwhile, a polymer layer 14 of a certain thickness remains on the bottom of the first intermediate etched structure 11, covering the substrate material below the bottom of the first intermediate etched structure 11. Figure 4 As shown, when starting the second etching step, for the first intermediate etch structure 11, the remaining polymer layer 14 at the bottom of the first intermediate etch structure 11 needs to be etched away first, exposing the substrate material below the bottom of the first intermediate etch structure 11, before etching of the substrate material below the bottom of the first intermediate etch structure 11 can begin. For the second intermediate etch structure 12, the substrate material exposed below the bottom of the second intermediate etch structure 12 can be etched directly. Therefore, when the remaining polymer layer 14 at the bottom of the first intermediate etch structure 11 is etched away, exposing the substrate material below, the substrate material below the bottom of the second intermediate etch structure 12 has already been etched to a certain depth, forming trench segments of a certain depth, such as... Figure 5 As shown. This allows for more effective etching time for etching the substrate material below the bottom of the second intermediate etch structure 12, and makes the effective etching time for the substrate material below the bottom of the second intermediate etch structure 12 greater than the effective etching time for the substrate material below the bottom of the first intermediate etch structure 11. Therefore, at the end of the second etching step, it helps to eliminate the difference in etching depth between the first intermediate etch structure 11 and the second intermediate etch structure 12 in the first periodic cycle, allowing the bottom of the first intermediate etch structure 11, with its increased etching depth, to be flush with the bottom of the second intermediate etch structure 12, as shown. Figure 6 As shown.

[0087] In some embodiments, a plasma formed by a second etching gas is used, and a second etching step is performed under a third pressure and a third bias power to etch the substrate material below the bottom of the first intermediate etched structure 11 and the bottom of the second intermediate etched structure 12.

[0088] In some embodiments, the third pressure is greater than the second pressure, and the third bias power is less than the first bias power. By minimizing the third bias power under an appropriate third pressure, the etching rate for removing the remaining polymer layer 14 on the bottom of the first intermediate etched structure 11 is reduced, thereby further increasing the effective etching time for the substrate material below the bottom of the second intermediate etched structure 12. Specifically, when the third bias power is zero, the etching rate for removing the remaining polymer layer 14 on the bottom of the first intermediate etched structure 11 is minimized. Simultaneously, under no bias voltage conditions, the substrate material below the bottom can be etched more effectively, and damage to the mask layer 13 (photoresist layer) can be reduced, which helps to avoid etching defects and maintain a good etching morphology.

[0089] In some embodiments, the second etching gas may include a fluorine-containing gas. For example, the second etching gas may include a fluorine-containing gas such as SF6. However, it is not limited to this.

[0090] In some embodiments, the flow rate of the second etching gas is 10 sccm to 1000 sccm. For example, the flow rate of the second etching gas may be 10 sccm, 15 sccm, 30 sccm, 60 sccm, 100 sccm, 200 sccm, 500 sccm, 800 sccm or 1000 sccm, or any value between any two of the aforementioned flow rate values.

[0091] In some embodiments, the third pressure is 30 mTorr to 300 mTorr. For example, the third pressure may be 30 mTorr, 35 mTorr, 60 mTorr, 90 mTorr, 110 mTorr, 160 mTorr, 200 mTorr, 250 mTorr or 300 mTorr, or any value between any two of the aforementioned pressure values.

[0092] In some embodiments, the third bias power is 0W to 10W, preferably 0W. For example, the third bias power can be 0W, 1W, 2W, 5W, 7W, 9W or 10W, or any value between any two of the aforementioned power values.

[0093] When performing the second etching step, based on the structure that the polymer layer 14 on the bottom of the second intermediate etched structure 12 has been completely etched away, while a polymer layer 14 of a certain thickness remains on the bottom of the first intermediate etched structure 11, and through the coordinated control of the flow rate, pressure, bias power, etc., at the end of the second etching step of the first cycle, a first intermediate etched structure 11 and a second intermediate etched structure 12 with increased etching depth and flush bottoms can be obtained. This eliminates the difference in etching depth between the first and second etched structures in each cycle, laying a good foundation for finally obtaining a first and second etched structure with flush bottoms.

[0094] Step S16: Repeat steps S13 to S15 until a first etched structure and a second etched structure with their bottoms flush are formed on the surface of the substrate, corresponding to the first intermediate etched structure formed by the increased etching depth and the second intermediate etched structure.

[0095] In some embodiments, to obtain a first etched structure and a second etched structure with a high aspect ratio, steps S13 to S15 can be repeated, i.e., using the method of the above embodiments of this application, continuing the deposition step in the second periodic cycle of the etching process, using a deposition gas with added first auxiliary gas, and under a first pressure and a first bias power, depositing polymer layers 14 again on the inner walls of the first intermediate etched structure 11 and the second intermediate etched structure 12, where the etching depth is increased, and such that the thickness and density of the polymer layer 14 at the bottom of the first intermediate etched structure 11 are greater than the thickness and density of the polymer layer 14 at the bottom of the second intermediate etched structure 12, such as... Figure 7As shown; then, the first etching step in the second cyclic step of the etching process is performed, using a first etching gas with a second auxiliary gas added, and under a second pressure and a second bias power, the polymer layer 14 redeposited on the bottom of the first intermediate etched structure 11 and the bottom of the second intermediate etched structure 12 is etched away, such that the polymer layer 14 redeposited on the bottom of the second intermediate etched structure 12 is completely removed, while the polymer layer 14 redeposited on the bottom of the first intermediate etched structure 11 still remains, as shown. Figure 8 As shown; next, the second etching step in the second cyclic step of the etching process is performed, using the second etching gas and under the third pressure and third bias power, etching is performed on the substrate material below the bottom of the first intermediate etched structure 11 (the remaining polymer layer 14 needs to be removed in this step) and the substrate material below the bottom of the second intermediate etched structure 12, so that the etching depth of the first intermediate etched structure 11 and the second intermediate etched structure 12 is further increased, and the bottoms are flush, as shown. Figure 9 As shown. Thus, by performing multiple cyclic steps of the etching process, a first etched structure 15 and a second etched structure 16 with high aspect ratios can be formed on the substrate 10, corresponding to the first intermediate etched structure 11 and the second intermediate etched structure 12, with the etching depth continuously increasing. The bottom of the first etched structure 15 is flush with the bottom of the second etched structure 16, as shown. Figure 10 As shown. Figure 10 The image shows a first etched structure 15 and a second etched structure 16 with high aspect ratio obtained on the substrate 10 after the mask layer 13 is removed. The first etched structure 15 with a top opening has a third width L3, and the second etched structure 16 with a top opening has a fourth width L4. The third width L3 is greater than the fourth width L4 (i.e., the trench width of the first etched structure 15 is greater than the trench width of the second etched structure 16), and the difference in etching depth between the first etched structure 15 and the second etched structure 16 is eliminated.

[0096] In some embodiments, the temperature during the etching process is 0°C to 80°C. For example, the temperature may be 0°C, 5°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, or 80°C, or any value between any two of the aforementioned temperature values.

[0097] In some embodiments, the source power is 100W to 3000W when performing the etching process. For example, the source power may be 100W, 200W, 500W, 850W, 1000W, 1500W, 2000W, 2500W or 3000W, or any value between any two of the aforementioned power values.

[0098] In some embodiments, the execution time of the deposition step, the first etching step, and / or the second etching step is 0.1s to 60s. For example, the time can be 0.1s, 0.2s, 0.5s, 1s, 5s, 10s, 20s, 30s, 40s, 50s, or 60s, or any value between any two of the aforementioned time values.

[0099] In some embodiments, an atmosphere displacement step may be added between any two adjacent steps in the deposition step, the first etching step, and the second etching step in the above-described periodic cycle. This step involves purging the substrate 10 with a displacement gas to replace the atmosphere in the first etched structure and the second etched structure under formation. This effectively reduces residual process gases and byproducts (e.g., residual C4F8, SF6, CF3). x Cross-interference caused by species, F radicals, SiF4 and other etching byproducts to adjacent steps. For example, an atmosphere replacement step can be added between the deposition step and the first etching step, between the first etching step and the second etching step, and between the second etching step and the deposition step.

[0100] In some embodiments, the replacement gas may include at least one of an inert gas (e.g., Ar) and nitrogen.

[0101] In a second aspect, embodiments of this application also provide a semiconductor structure, the semiconductor structure including a substrate and a first etched structure and a second etched structure simultaneously formed on the substrate, the semiconductor structure being obtained using an etching method for improving high aspect ratio loading effects as provided in any of the embodiments of the first aspect above.

[0102] refer to Figure 10 In some embodiments, a semiconductor structure is formed on a substrate 10. A first etched structure 15 and a second etched structure 16 with a high aspect ratio and a top opening are provided on the surface of the substrate 10. The first etched structure 15 has a third width L3, and the second etched structure 16 has a fourth width L4. The third width L3 is greater than the fourth width L4. The bottoms of the first etched structure 15 and the second etched structure 16 are located within the substrate 10 and are flush with each other. The first etched structure 15 and the second etched structure 16 are simultaneously formed using an etching method for improving the high aspect ratio loading effect provided in any of the embodiments of the first aspect described above, resulting in the semiconductor structure of this application embodiment.

[0103] In a third aspect, embodiments of this application also provide a plasma processing apparatus for performing the etching method corresponding to the above embodiments to improve the high aspect ratio loading effect in order to obtain the semiconductor structure corresponding to the above embodiments. The plasma processing apparatus includes inductively coupled plasma (ICP) processing equipment or capacitively coupled plasma (CCP) processing equipment, etc.

[0104] In other aspects, embodiments of this application also provide an electronic device, including a semiconductor structure obtained using the etching method described above to improve the high aspect ratio loading effect. The electronic device can be a storage device, mobile phone, computer, tablet computer, electronic instrument, television, artificial intelligence device, etc.

[0105] In summary, the embodiments of this application improve the problem that traditional high aspect ratio etching processes cannot simultaneously address the issue of wide trenches (first etched structure 15) and narrow trenches (second etched structure 16) by coordinating the deposition step, the first etching step, the second etching step, and the atmosphere replacement step. In each cycle, it can suppress over-etching at the bottom of the wide trench while promoting the removal of the polymer layer 14 at the bottom of the narrow trench, reducing the etching depth difference between the wide and narrow trenches, and improving the quality of residue at the bottom of the narrow trench, trench closure, and sidewall morphology, thereby improving the processing consistency of high aspect ratio silicon structures such as MEMS and TSV.

[0106] The above are merely preferred embodiments of this application. These embodiments are not intended to limit the scope of protection of this application. Therefore, any equivalent changes made based on the description and drawings of this application should also be included within the scope of protection of this application.

Claims

1. An etching method for improving high aspect ratio loading effects, characterized in that, include: Provide substrate; The surface of the substrate is etched using a plasma etching process that includes a deposition step, a first etching step, and a second etching step in sequence, thereby simultaneously forming a first etched structure and a second etched structure on the substrate, wherein the width of the first etched structure is greater than the width of the second etched structure. In the deposition step, when depositing polymer layers on the first inner wall of the first etched structure and the second inner wall of the second etched structure, ion-assisted deposition is performed using a first auxiliary gas, and the high aspect ratio loading effect is utilized to make the density of the polymer layer formed on the bottom of the first inner wall greater than the density of the polymer layer formed on the bottom of the second inner wall. When performing the first etching step to etch and remove the polymer layers on the bottom of the first inner wall and the bottom of the second inner wall, ion-assisted etching is performed using a second auxiliary gas to weaken the effect of the high aspect ratio loading effect. This ensures that when the polymer layer on the bottom of the second inner wall is completely removed, the polymer layer on the bottom of the first inner wall remains. This allows the effective etching time for the substrate material below the bottom of the second inner wall to be longer than the effective etching time for the substrate material below the bottom of the first inner wall when performing the second etching step to etch the substrate material below the bottom of the first inner wall. This results in the bottom of the final etched structure being flush with the bottom of the second etched structure.

2. The etching method for improving high aspect ratio loading effect according to claim 1, characterized in that, By performing the deposition step under a first pressure and a first bias power, the ion bombardment effect of the first auxiliary gas ions on the polymer layer formed on the bottom of the first inner wall is stronger than the ion bombardment effect on the polymer layer formed on the bottom of the second inner wall, thereby compacting the polymer layer formed on the bottom of the first inner wall, resulting in a higher density of the polymer layer formed on the bottom of the first inner wall than the polymer layer formed on the bottom of the second inner wall. By performing the first etching step under a second pressure and a second bias power, the auxiliary etching capability of the second auxiliary gas ions on the polymer layer on the bottom of the second inner wall is improved, promoting the rapid removal of the polymer layer on the bottom of the second inner wall. This results in a longer effective etching time for the substrate material below the bottom of the second inner wall than for the substrate material below the bottom of the first inner wall during the second etching step, with the first pressure being greater than the second pressure, and the first bias power being greater than zero and less than the second bias power. And / or, during the deposition step, a high aspect ratio loading effect is also utilized to make the thickness of the polymer layer formed on the bottom of the first inner wall greater than the thickness of the polymer layer formed on the bottom of the second inner wall.

3. The etching method for improving high aspect ratio loading effect according to claim 2, characterized in that, The second etching step is performed under a third pressure and a third bias power to reduce the etching rate of the remaining polymer layer on the bottom of the first inner wall, thereby further increasing the effective etching time for the substrate material below the bottom of the second inner wall; the third pressure is greater than the second pressure, and the third bias power is less than the first bias power.

4. The etching method for improving high aspect ratio loading effect according to claim 3, characterized in that, The first pressure is 30 mTorr to 300 mTorr, and the first bias power is 10 W to 50 W; and / or, the second pressure is 10 mTorr to 50 mTorr, and the second bias power is 200 W to 500 W; and / or, the third pressure is 30 mTorr to 300 mTorr, and the third bias power is 0 W to 10 W; and / or, the first bias power is applied in a pulsed manner; and / or, the second bias power is applied in a pulsed manner.

5. The etching method for improving high aspect ratio loading effect according to claim 1, characterized in that, During the deposition step, a deposition gas is used to deposit polymer layers on the first inner wall of the first etched structure and the second inner wall of the second etched structure, and a first auxiliary gas is added to the deposition gas for ion-assisted deposition. The deposition gas includes a fluorocarbon gas, and the first auxiliary gas includes a first non-reactive gas. During the first etching step, a first etching gas is used to remove the polymer layers on the bottom of the first and second inner walls, and a second auxiliary gas is added to the first etching gas to improve the etching capability of the polymer layers on the bottom of the second inner wall. The first etching gas includes a second non-reactive gas, and the second auxiliary gas includes an oxidizing gas. During the second etching step, a second etching gas is used to etch the substrate material below the bottom of the first and second inner walls. The second etching gas includes a fluorine-containing gas.

6. The etching method for improving high aspect ratio loading effect according to claim 5, characterized in that, The fluorocarbon gas includes C4F8; and / or, the first non-reactive gas includes at least one of an inert gas and nitrogen; and / or, the second non-reactive gas includes an inert gas; and / or, the oxidizing gas includes oxygen; and / or, the flow rate of the second auxiliary gas is greater than the flow rate of the first etching gas; and / or, the fluorine-containing gas includes SF6.

7. The etching method for improving high aspect ratio loading effect according to claim 5, characterized in that, When performing the second etching step, for the first etched structure being formed, the remaining polymer layer at the bottom of the first inner wall is first etched away, and then the substrate material below the bottom of the first inner wall is etched. For the second etched structure being formed, the substrate material exposed below the bottom of the second inner wall is directly etched.

8. The etching method for improving high aspect ratio loading effect according to claim 1, characterized in that, Also includes: Atmosphere replacement step; the atmosphere replacement step is performed between any two adjacent steps in the periodic cycle of the deposition step, the first etching step and the second etching step, and is used to replace the atmosphere in the first etched structure and the second etched structure being formed by introducing a replacement gas.

9. The etching method for improving high aspect ratio loading effect according to claim 8, characterized in that, The replacement gas includes at least one of an inert gas and nitrogen.

10. A semiconductor structure, comprising a substrate and a first etched structure and a second etched structure simultaneously formed on the substrate, characterized in that, The semiconductor structure is obtained using the etching method described in any one of claims 1-9 to improve the high aspect ratio loading effect.

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