Method for etching window of shallow trench isolation and via etching process
By using polymer as the sidewall protective layer during the etching process, an etching window with a certain inclination angle is formed, which solves the problem of poor etching of shallow trenches, and improves the isolation effect and device performance.
Patent Information
- Application Number
- CN202111266553.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-10-28
- Publication Date
- 2025-07-18
- Estimated Expiration
- 2041-10-28
AI Technical Summary
In the prior art, shallow trench etching has poor morphology, resulting in poor isolation effect and affecting device performance.
By using polymer as the sidewall protective layer during the etching process, an etching window with a certain inclination angle is formed, ensuring that the polymer is concentrated inside the etching window, and the etching process is controlled using specific gases and parameters to form a good shallow trench and through-hole morphology.
The etching morphology quality of shallow trenches and through holes is improved, the occurrence of bad morphology is reduced, the isolation effect is enhanced, and the performance of semiconductor devices is improved.
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Figure CN113990751B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of integrated circuit manufacturing processes, and particularly to a method for etching windows in a shallow trench isolation and via etching process. Background Art
[0002] While the dimensions such as the channel length, junction depth, and gate oxide thickness of a device are scaled down proportionally, the power supply voltage does not decrease proportionally. This leads to a significant increase in the lateral and longitudinal electric fields in the channel region, and further causes the degradation of device characteristics to become more serious. Therefore, the process window of shallow trench isolation has also become the focus of research. In terms of the isolation process itself, the rationality of the trench morphology plays a crucial role. Due to the characteristics of the process, shallow trenches generally require an inclination angle of 85 degrees to 87 degrees, which in turn determines that a certain amount of polymer is needed to protect the sidewalls during the etching process. Improper polymer protection is likely to result in a poor shallow trench morphology, and a poor shallow trench morphology is likely to cause premature sealing during subsequent filling, leading to insufficient filling and further affecting the isolation effect. Therefore, ensuring the stability and rationality of the shallow trench etching morphology is the key to improving the quality of the shallow trench isolation etching process window. Summary of the Invention
[0003] The purpose of the present invention is to provide a method to solve the problem of poor etching morphology of shallow trenches and vias.
[0004] To achieve the above object, the present invention provides a method for etching windows in a shallow trench isolation etching process, including:
[0005] Providing a substrate;
[0006] Forming a silicon oxide layer on the substrate;
[0007] Forming a silicon nitride layer on the silicon oxide layer;
[0008] Forming a first bottom anti-reflection coating on the silicon nitride layer;
[0009] Forming a photoresist layer on the first bottom anti-reflection coating;
[0010] Performing a first lithography on the photoresist layer and the first bottom anti-reflection coating through an etching process to form a first window on the upper surface of the silicon nitride layer;
[0011] Performing a second lithography on the silicon nitride layer and the silicon oxide layer along the first window through an etching process to form a second window;
[0012] Removing the photoresist layer and the first bottom anti-reflection coating to form a third window on the silicon nitride layer and the silicon oxide layer;
[0013] Forming a second bottom anti-reflection coating on the silicon nitride layer and within the third window thereon;
[0014] Remove the second bottom anti-reflection coating on the silicon nitride layer;
[0015] Perform the third photolithography on the second bottom anti-reflection coating in the third window to the substrate through an etching process, and use the polymer generated by etching the second bottom anti-reflection coating in the third window as a sidewall protection layer. Use the sidewall protection layer as a barrier layer to form a fourth window with a certain inclination angle on the silicon nitride layer, silicon oxide layer and substrate. The fourth window is a shallow trench for shallow trench isolation.
[0016] Furthermore, for the method of etching windows in the shallow trench isolation etching process provided by the present invention, the gases and parameters used for removing the second bottom anti-reflection coating on the silicon nitride layer are as follows:
[0017] The gas and flow rate used are: CF4, 80 - 100 sccm;
[0018] The RF power is: 300 - 400 w;
[0019] The RF voltage is: 120 - 180 V;
[0020] The gas pressure is: 5 - 8 mtorr.
[0021] Furthermore, for the method of etching windows in the shallow trench isolation etching process provided by the present invention, in the method of using the polymer generated by etching the second bottom anti-reflection coating in the third window as a sidewall protection layer and using the sidewall protection layer as a barrier layer to form a fourth window with a certain inclination angle on the silicon nitride layer, silicon oxide layer and substrate, where the fourth window is a shallow trench for shallow trench isolation, the etching parameters are as follows:
[0022] Among them, the etching gas and flow rate include: HBr, 350 - 380 sccm; O2, 9 - 12 sccm; SF6 6 - 9 sccm;
[0023] The RF power is: 1000 - 1200 w;
[0024] The RF voltage is: 170 - 200 V;
[0025] The gas pressure is: 12 - 18 mtorr.
[0026] Furthermore, for the method of etching windows in the shallow trench isolation etching process provided by the present invention, the silicon oxide layer is silicon dioxide.
[0027] Furthermore, for the method of etching windows in the shallow trench isolation etching process provided by the present invention, the silicon nitride layer is silicon nitride or silicon oxynitride.
[0028] Further, the method for etching a window in the shallow trench isolation etching process provided by the present invention further includes: removing by-products generated during etching.
[0029] Further, in the method for etching a window in the shallow trench isolation etching process provided by the present invention, oxygen is used to remove by-products generated during etching.
[0030] Further, in the method for etching a window in the shallow trench isolation etching process provided by the present invention, the shallow trench isolation etching process is a double trench lithography process, a double line lithography process, a triple lithography process, or a self-aligned dual imaging lithography process.
[0031] To achieve the above object, the present invention also provides a method for etching a window in a via etching process, including:
[0032] Etching a trench in the via material to be etched, and the trench is a blind trench;
[0033] Filling a bottom anti-reflection coating in the trench;
[0034] Using the polymer generated by etching the bottom anti-reflection coating in the trench as a sidewall protection layer, and using the sidewall protection layer as a barrier layer to form a window with a certain inclination angle penetrating through the via material to be etched, and the window is a via.
[0035] Further, the method for etching a window in the via etching process provided by the present invention further includes:
[0036] Removing by-products generated during via etching.
[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0038] In the method for etching a window in the shallow trench isolation and via etching processes provided by the present invention, through the sufficiency and proximity of generating polymers inside the etched window, the inclination of the etched profiles of the shallow trench and the via can be more fully and sufficiently ensured, forming shallow trenches and vias with better profiles, avoiding the formation of poor profiles such as straight, multi-slope, or low-position ones, reducing the occurrence probability of shallow trench and via failures, and ensuring the yield of shallow trench isolation and vias.
[0039] In the method for etching a window in the shallow trench isolation and via etching processes provided by the present invention, the source of the polymer generated by etching is concentrated inside the etched window, which greatly ensures the sidewall protection degree of the window being etched, can avoid the formation of poor profiles such as low-position or multi-slope ones with a slope more than double, expands the filling process window, and improves the quality of the etched profiles of the shallow trench or via.
[0040] The method for etching windows in the shallow trench isolation and via etching process provided by the present invention concentrates the polymers generated during etching inside the etching windows, and can expand the process window of the trench inclination through the sidewall transfer effect, ensuring a good isolation effect.
[0041] The method for etching windows in the shallow trench isolation and via etching process provided by the present invention has a relatively large amount of polymers adhering to the sidewalls of the etching windows, which can reduce plasma damage during etching and improve the performance of semiconductor devices. BRIEF DESCRIPTION OF THE DRAWINGS
[0042] Figures 1 to 8 is a schematic structural diagram of the process of etching a shallow trench;
[0043] As shown in the figure:
[0044] 101, substrate;
[0045] 102, silicon oxide layer;
[0046] 103, silicon nitride layer;
[0047] 104, first bottom anti-reflection coating;
[0048] 105, photoresist layer;
[0049] 106, second bottom anti-reflection coating;
[0050] 200, shallow trench;
[0051] 201, first window;
[0052] 202, second window;
[0053] 203, third window;
[0054] 204, fourth window. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0055] The following further details the metal wire digging hole structure and method proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. According to the following description and the claims, the advantages and features of the present invention will be clearer. It should be noted that the drawings are all in a very simplified form and use non-precise scales, only for conveniently and clearly assisting in explaining the purpose of the embodiments of the present invention.
[0056] Please refer to Figures 1 to 8 , an embodiment of the present invention provides a method for etching windows in a shallow trench isolation etching process, where Figures 1 to 8 is a double trench lithography process, including:
[0057] Step 301, please refer to Figure 1 , provide a substrate 101. The substrate 101 can be a silicon substrate.
[0058] Step 302, refer to Figure 1 , form a silicon oxide layer 102 on the substrate 101. The silicon oxide layer 102 is silicon dioxide.
[0059] Step 303, refer to Figure 1 , form a silicon nitride layer 103 on the silicon oxide layer 102. The silicon nitride layer 103 can be silicon nitride or silicon oxynitride.
[0060] Step 304, refer to Figure 1 , form a first bottom anti-reflection coating 104 on the silicon nitride layer 103.
[0061] Step 305, refer to Figure 1 , form a photoresist layer 105 on the first bottom anti-reflection coating 104.
[0062] Step 306, refer to Figure 2 , perform the first lithography on the photoresist layer 105 and the first bottom anti-reflection coating 104 through an etching process to form a first window 201 on the upper surface of the silicon nitride layer 103.
[0063] Step 307, refer to Figure 3 , perform the second lithography on the silicon nitride layer 103 and the silicon oxide layer 102 along the first window 201 through an etching process to form a second window 202.
[0064] Step 308, refer to Figure 4 , remove the photoresist layer 105 and the first bottom anti-reflection coating 104 to form a third window 203 on the silicon nitride layer 103 and the silicon oxide layer 102.
[0065] Step 309, refer to Figure 5 , form a second bottom anti-reflection coating 106 on the silicon nitride layer 103 and within the third window 203 thereon.
[0066] Step 310, refer to Figure 6 , remove the second bottom anti-reflection coating 106 on the silicon nitride layer 103. Retain the second bottom anti-reflection coating 106 within the third window 203.
[0067] Step 311, refer to Figures 7 to 8, the second bottom anti-reflection coating 106 in the third window 203 is lithographed into the substrate 101 for the third time through an etching process, and the polymer generated by etching the second bottom anti-reflection coating 106 in the third window 203 is used as a sidewall protection layer. With the sidewall protection layer as a barrier layer, a fourth window with a certain inclination angle is formed on the silicon nitride layer 103, the silicon oxide layer 102, and the substrate 101. The fourth window is the shallow trench 200 for shallow trench isolation.
[0068] Please refer to Figure 6 , in order to improve the removal quality of the second bottom anti-reflection coating 106, the method for etching a window in the shallow trench isolation etching process provided by the embodiment of the present invention, the gases and parameters for removing the second bottom anti-reflection coating 106 on the silicon nitride layer 103 are as follows:
[0069] The used gas and its flow rate are: CF4, 80 - 100 sccm; the radio frequency power is: 300 - 400 w; the radio frequency voltage is: 120 - 180 V; the gas pressure is: 5 - 8 mtorr.
[0070] Furthermore, in the method for etching a window in the shallow trench isolation etching process provided by the embodiment of the present invention, the polymer generated by etching the second bottom anti-reflection coating 106 in the third window 203 is used as a sidewall protection layer. With the sidewall protection layer as a barrier layer, the etching parameters in the method for forming a fourth window with a certain inclination angle on the silicon nitride layer 103, the silicon oxide layer 102, and the substrate 101, and the fourth window being the shallow trench 200 for shallow trench isolation are as follows:
[0071] Among them, the etching gas and its flow rate include: HBr, 350 - 380 sccm; O2, 9 - 12 sccm; SF6 6 - 9 sccm; the radio frequency power is: 1000 - 1200 w; the radio frequency voltage is: 170 - 200 V; the gas pressure is: 12 - 18 mtorr.
[0072] Please refer to Figures 2 to 4 , Figures 7 to 8 , in order to improve the etching quality, the method for etching a window in the shallow trench isolation etching process provided by the embodiment of the present invention further includes: removing the by-products generated during etching. For example: the by-products generated during etching can be removed by oxygen.
[0073] The method for etching a window in the shallow trench isolation etching process provided by the embodiment of the present invention, the shallow trench isolation etching process can be the above-mentioned double trench lithography process, or a double line lithography process, a triple lithography process, or a self-aligned dual imaging lithography process.
[0074] To achieve the above object, the present invention also provides a method for etching a window in a via etching process, including:
[0075] Step 401: Etch trenches in the material of the via to be etched, where the trenches are blind trenches.
[0076] Step 402: Fill the trenches with a bottom anti-reflective coating.
[0077] Step 403: Use the polymer generated by etching the bottom anti-reflective coating in the trenches as a sidewall protection layer, and use the sidewall protection layer as a barrier layer to form a window with a certain inclination angle penetrating the material of the via to be etched, where the window is a through hole.
[0078] To improve the etching quality, the method for etching a window in the via etching process provided by the embodiments of the present invention further includes:
[0079] Remove the by-products generated during the etching of the through hole.
[0080] The method for etching a window in the shallow trench isolation and via etching process provided by the embodiments of the present invention can more fully and sufficiently ensure the inclination of the etching profiles of the shallow trenches and vias by the sufficiency and proximity of the polymer generated inside the etched window, form shallow trenches and vias with better profiles, avoid forming poor profiles such as straight, multi-slope or low-position ones, reduce the occurrence probability of the failure of the shallow trenches and vias, and ensure the yield of the shallow trench isolation and vias.
[0081] The method for etching a window in the shallow trench isolation and via etching process provided by the embodiments of the present invention concentrates the source of the polymer generated by etching inside the etched window, greatly ensures the sidewall protection degree of the window being etched, can avoid forming poor profiles such as low-position or multi-slope ones with a slope more than double, expands the filling process window, and improves the quality of the etching profiles of the shallow trenches or vias.
[0082] The method for etching a window in the shallow trench isolation and via etching process provided by the embodiments of the present invention concentrates the polymer generated by etching inside the etched window, can expand the process window of the trench inclination through the sidewall transfer effect, and ensure a good isolation effect.
[0083] The method for etching a window in the shallow trench isolation and via etching process provided by the embodiments of the present invention has a relatively large amount of polymer adhering to the sidewalls of the etched window, can reduce the plasma damage during the etching process, and improve the performance of semiconductor devices.
[0084] The above description is only a description of the preferred embodiments of the present invention, and does not limit the scope of the present invention in any way. Any changes and modifications made by those of ordinary skill in the art of the present invention according to the above disclosure belong to the protection scope of the claims of the present invention.
Claims
1. A method for etching windows in a shallow trench isolation etching process, characterized in that, Including: Providing a substrate; Forming a silicon oxide layer on the substrate; Forming a silicon nitride layer on the silicon oxide layer; Forming a first bottom anti-reflection coating on the silicon nitride layer; Forming a photoresist layer on the first bottom anti-reflection coating; Performing a first lithography on the photoresist layer and the first bottom anti-reflection coating through an etching process to form a first window on the upper surface of the silicon nitride layer; Performing a second lithography on the silicon nitride layer and the silicon oxide layer along the first window through an etching process to form a second window; Removing the photoresist layer and the first bottom anti-reflection coating to form a third window on the silicon nitride layer and the silicon oxide layer; Forming a second bottom anti-reflection coating on the silicon nitride layer and within the third window thereon; Removing the second bottom anti-reflection coating on the silicon nitride layer; Performing a third lithography on the second bottom anti-reflection coating within the third window through an etching process to the inside of the substrate, using the polymer generated by etching the second bottom anti-reflection coating within the third window as a sidewall protection layer, and using the sidewall protection layer as a barrier layer to form a fourth window with a certain inclination angle on the silicon nitride layer, the silicon oxide layer and the substrate, wherein the fourth window is a shallow trench for shallow trench isolation; The gas and parameters for removing the second bottom anti-reflection coating on the silicon nitride layer are as follows: The gas and flow rate used are: CF4, 80 - 100 sccm; The RF power is: 300 - 400 w; The RF voltage is: 120 - 180 V; The gas pressure is: 5 - 8 mtorr.
2. The method for etching window of shallow trench isolation etching process as claimed in claim 1, wherein The etching parameters in the method of using the polymer generated by etching the second bottom anti-reflection coating within the third window as a sidewall protection layer, and using the sidewall protection layer as a barrier layer to form a fourth window with a certain inclination angle on the silicon nitride layer, the silicon oxide layer and the substrate, wherein the fourth window is a shallow trench for shallow trench isolation are as follows: The etching gas and flow rate include: HBr, 350 - 380 sccm; O2, 9 - 12 sccm; SF6 6 - 9 sccm; The RF power is: 1000 - 1200 w; The RF voltage is: 170 - 200 V; The gas pressure is: 12 - 18 mtorr.
3. The method for etching window of shallow trench isolation etching process according to claim 1, characterized in that The silicon oxide layer is silicon dioxide.
4. The method for etching windows in the shallow trench isolation etching process according to claim 1, characterized in that, The silicon nitride layer is silicon nitride or silicon oxynitride.
5. The method for etching windows in a shallow trench isolation etching process as claimed in claim 1, wherein Also including: Removing the by-products generated during etching.
6. The method for etching window of shallow trench isolation etching process according to claim 5, characterized in that, Removing the by-products generated during etching through oxygen.
7. The method for etching a window of a shallow trench isolation etching process according to claim 1, wherein The shallow trench isolation etching process is a double trench lithography process, a double line lithography process, a triple lithography process or a self-aligned dual imaging lithography process.
Citation Information
Patent Citations
Method for preventing depth load effect from occurring in shallow-trench isolation structure
CN105355587A