Semiconductor structure and method for forming the same

Abstract

A semiconductor structure and a method for forming the same, wherein the method comprises: providing an initial substrate having a plurality of separate mask layers thereon; forming a sacrificial film on the initial substrate, the sacrificial film covering the sidewall surfaces and top surface of the mask layer, wherein the material of the sacrificial film has a first atomic percentage of oxygen; forming a sacrificial opening within the sacrificial film, wherein the bottom of the sacrificial opening exposes at least one top surface of the mask layer; after forming the sacrificial opening, etching the mask layer using the sacrificial film as a mask using a first etching process until the surface of the initial substrate is exposed; after the first etching process, modifying the sacrificial film to form a sacrificial layer, wherein the material of the sacrificial layer has a second atomic percentage of oxygen, wherein the second atomic percentage is less than the first atomic percentage; and after the modification process, removing the sacrificial layer. The method is advantageous in reducing process costs and saving process time.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to a semiconductor structure and a method for forming the same. Background Art

[0002] With the rapid development of semiconductor technology, the feature size of semiconductor devices continues to shrink, leading to increasingly higher levels of integration in integrated circuits. This has also placed higher demands on semiconductor manufacturing processes. Etching is a key process in semiconductor manufacturing, transferring the pattern on the mask to the material layer. However, as feature sizes continue to decrease, the wavelength limit of the photolithography process has caused the process to encounter bottlenecks, making it impossible to etch smaller trenches.

[0003] To increase the integration density of semiconductor memory devices, various methods have been employed in the prior art. Self-aligned multi-patterning (SAMP) is a widely accepted and applied solution in semiconductor device fabrication. Commonly used SAMP techniques include self-aligned double patterning (SADP) and self-aligned quadruple patterning (SAQP). SAMP allows for the fabrication of smaller node devices using existing photolithography techniques, thereby minimizing process variation.

[0004] However, the existing self-aligned multi-patterning technology must introduce complex film layer stacking to achieve pattern transfer. When etching the film layer to form the target pattern on the semiconductor substrate, it is prone to poor graphic transfer quality and distortion of the target pattern, which has a negative impact on the robustness of the device.

[0005] Therefore, the performance of semiconductor structures formed using the existing self-aligned multi-patterning technology needs to be improved. Summary of the Invention

[0006] The technical problem solved by the present invention is to provide a semiconductor structure and a method for forming the same, so as to reduce process costs and save process time.

[0007] To solve the above technical problems, an embodiment of the present invention provides a method for forming a semiconductor structure, comprising: providing an initial substrate, wherein the initial substrate has a plurality of separate mask layers; forming a sacrificial film on the initial substrate, wherein the sacrificial film covers the sidewall surface and the top surface of the mask layer, and the oxygen in the material of the sacrificial film has a first atomic percentage; forming a sacrificial opening in the sacrificial film, and the bottom of the sacrificial opening exposes at least one top surface of the mask layer; after forming the sacrificial opening, adopting a first etching process, using the sacrificial film as a mask, etching the mask layer until the surface of the initial substrate is exposed; after the first etching process, performing a modification treatment on the sacrificial film, so that the sacrificial film forms a sacrificial layer, and the oxygen in the material of the sacrificial layer has a second atomic percentage, and the second atomic percentage is less than the first atomic percentage; after the modification treatment, removing the sacrificial layer.

[0008] Optionally, the first atomic percentage range is 30% to 80%; the second atomic percentage range is 0% to 5%.

[0009] Optionally, the material of the sacrificial film also contains carbon.

[0010] Optionally, the ratio of the number of oxygen atoms to the number of carbon atoms in the material of the sacrificial film is in the range of 0.2:1 to 0.8:1.

[0011] Optionally, the material of the sacrificial layer is amorphous carbon.

[0012] Optionally, the process for forming the sacrificial film is a physical vapor deposition process; the parameters of the physical vapor deposition process include: using graphite as a target material, the gas introduced includes: oxygen or argon, the gas flow rate is 20 standard ml / min to 200 standard ml / min, the pressure is 2 mTorr to 100 mTorr, and the DC power is 200 W to 800 W.

[0013] Optionally, the modification process includes: a rapid annealing process; the process parameters of the rapid annealing process include: a temperature range of 100 degrees Celsius to 500 degrees Celsius, and a time of 30 seconds to 300 seconds.

[0014] Optionally, the material of the mask layer is different from the material of the sacrificial film; the material of the mask layer includes: silicon, silicon oxide, silicon nitride or titanium oxide.

[0015] Optionally, the etching rate of the mask layer in the first etching process is greater than the etching rate of the sacrificial film; the first etching process is a wet etching process; the first etching process is a wet etching process; the process parameters of the wet etching include: the etching solution used is dilute sulfuric acid.

[0016] Optionally, the process of removing the sacrificial layer includes: a dry etching process, a wet etching process or an ashing process.

[0017] Optionally, the process for removing the sacrificial layer is an ashing process; parameters of the ashing process include: the gas used is an oxygen-containing gas, such as oxygen or ozone.

[0018] Optionally, the method for forming the sacrificial opening includes: forming a patterned layer on the surface of the sacrificial film, the patterned layer having a patterned opening, and the position and size of the patterned opening correspond to the position and size of the sacrificial opening; using a second etching process, using the patterned layer as a mask, etching the sacrificial film until the top surface of the mask layer is exposed, thereby forming a sacrificial opening in the sacrificial film.

[0019] Optionally, the second etching process is a dry etching process; the parameters of the dry etching process include: the etching gas used includes carbon monoxide, silicon dioxide, argon or sulfur dioxide, the gas flow rate is 100 standard ml / min to 500 standard ml / min, the temperature is 10 degrees Celsius to 60 degrees Celsius, the pressure is 4 mTorr to 50 mTorr, the source power is 100 watts to 800 watts, and the bias power is 0 watts to 200 watts.

[0020] Optionally, the method for forming the mask layer includes: forming a plurality of mutually discrete core layers on the initial substrate; forming a mask material layer on the surface of the initial substrate, the top surface of the core layer and the side wall surface; etching back the mask material layer until the surface of the initial substrate and the top surface of the core layer are exposed, thereby forming a mask layer on the initial substrate; after forming the mask layer, removing the core layer.

[0021] Optionally, the material of the core layer includes: silicon, silicon nitride, silicon oxide, amorphous carbon or optical resist material.

[0022] Optionally, the initial base includes an initial substrate and a hard mask material layer located on a surface of the initial substrate.

[0023] Optionally, the material of the hard mask material layer includes silicon, silicon oxide, silicon oxynitride or silicon oxycarbide.

[0024] Optionally, the method further includes: after removing the sacrificial layer, etching the initial substrate using the mask layer as a mask to form a substrate.

[0025] Correspondingly, the technical solution of the present invention also provides a semiconductor structure formed by any of the above methods.

[0026] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects:

[0027] In the method for forming a semiconductor structure provided by the technical solution of the present invention, a sacrificial layer is formed by modifying the sacrificial film, wherein the material of the sacrificial film has a first atomic percentage of oxygen, and the material of the sacrificial layer has a second atomic percentage of oxygen, and the second atomic percentage is less than the first atomic percentage. When the atomic percentage of oxygen in the material of the sacrificial layer is relatively low, it is advantageous to select a suitable process. During the process of removing the sacrificial layer, etching damage to the surface of the initial substrate and the mask layer located on the initial substrate is relatively small, making removal of the sacrificial layer less difficult, thereby reducing process costs and saving process time.

[0028] Furthermore, before the modification process, the sacrificial film material has a first atomic percentage of oxygen, the sacrificial film material has a higher atomic percentage of oxygen, and the sacrificial film also contains carbon. Because the bond energy of a CO bond is greater than that of a CC bond, a higher energy is required to open the CO bond, resulting in better etching resistance for the sacrificial film. Furthermore, during the second etching process, during etching of a portion of the sacrificial film, the sacrificial film's better etching resistance results in a better morphology of the sacrificial film after the sacrificial opening is formed, which facilitates improved pattern transfer accuracy, thereby improving the process window and resulting in better performance of the resulting semiconductor structure.

[0029] Furthermore, the material of the sacrificial film also contains carbon, that is, the sacrificial film contains oxygen and carbon. When the sacrificial film is subjected to rapid annealing, under high temperature conditions, the atoms in the sacrificial film material are easily rearranged, and CC sp 2 Bonds are formed, thereby releasing oxygen atoms and forming amorphous carbon. Within a reasonable temperature range, as the temperature increases and the processing time increases, the rapid annealing process can fully modify the sacrificial film material. The rapid annealing process is simple and easy to operate. Therefore, using the rapid annealing process to form the sacrificial layer can save process time. On the other hand, the ashing process can effectively remove amorphous carbon from the substrate, that is, completely remove the sacrificial layer. The ashing process is simple to operate and helps save process time. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figures 1 to 5 The present invention is a structural schematic diagram of each step of a method for forming a semiconductor structure;

[0031] Figures 6 to 16 1 is a schematic structural diagram of each step of a method for forming a semiconductor structure in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] As described in the background art, the performance of the existing semiconductor structure is poor.

[0033] The following is a detailed description of the reasons for the poor performance of the semiconductor structure with reference to the accompanying drawings. Figures 1 to 5 The present invention is a structural schematic diagram of each step of a method for forming a semiconductor structure.

[0034] Please refer to Figure 1 , providing an initial substrate 100 having a plurality of separate mask layers 110 thereon.

[0035] Please refer to Figure 2 A sacrificial film 120 is formed on the initial substrate 100 , and the sacrificial film 120 covers the sidewall surfaces and the top surface of the mask layer 110 .

[0036] Please refer to Figure 3 A patterned layer 130 is formed on the surface of the sacrificial film 120 , wherein the patterned layer 130 has an opening 131 therein, and the opening 131 is located on the surface of the sacrificial film 120 on at least one mask layer 130 .

[0037] Please refer to Figure 4 , using the patterned layer 130 as a mask, etching the sacrificial film 120 and the mask layer 110 until the surface of the initial substrate 100 is exposed; after etching the sacrificial film 120 and the mask layer 110, removing the patterned layer 130.

[0038] Please refer to Figure 5 After etching the sacrificial film 120 and the mask layer 110 , the sacrificial film 120 is removed; after removing the sacrificial film 120 , the initial substrate 110 is etched using the mask layer 110 as a mask to form a substrate 140 .

[0039] In the above method, the patterned layer 130 has openings 131 therein. By etching the sacrificial film 120 and mask layer 110 using the patterned layer 130 as a mask, the mask layer 110 corresponding to the openings 131 is removed, thereby changing the spacing between the formed mask layers 110. Furthermore, using the mask layer 110 as a mask, the initial substrate 100 is etched, resulting in adjacent substrates 140 having different sizes, thereby meeting process requirements.

[0040] However, the material of the sacrificial film 120 is usually an organic material containing carbon and oxygen. The reason is that the organic material containing carbon and oxygen has fluidity, which is conducive to filling and forming a flat surface. However, the etching resistance of the organic material containing carbon and oxygen is poor. Therefore, after etching, the pattern in the sacrificial film 120 is significantly different from the pattern of the patterned layer 130, that is, the accuracy of the pattern transfer is poor. With the improvement of the integration of semiconductor devices, due to the poor accuracy of the pattern of the sacrificial film 120, when the mask layer 130 is subsequently etched using the sacrificial film 120 as a mask, it is easy to cause the etching of the mask layer 130 to deviate, resulting in a poor process window, and even causing the formed mask layer 130 to be different from the designed pattern, resulting in poor performance of the formed semiconductor structure.

[0041] In order to solve the above technical problems, a material with good density and good etching resistance, such as fluid silicon oxide or silicon nitride, can be used to replace the organic material containing oxygen and carbon to form the sacrificial film 120. The sacrificial film 120 formed of silicon oxide or silicon nitride is etched using the patterned layer 130 as a mask. After etching, the morphology of the sacrificial film 120 is better, thereby improving the accuracy of the pattern transfer. However, the mask layer 130 is still etched using the sacrificial film 120 as a mask to remove the mask layer 130 corresponding to the opening 131 in the patterned layer 130. The existing process is difficult to remove silicon oxide or silicon nitride, resulting in a more complicated process and increased process costs.

[0042] To address the aforementioned technical issues, the present invention provides a method for forming a semiconductor structure, wherein a sacrificial film is modified to form a sacrificial layer, wherein the material of the sacrificial layer has a second atomic percentage of oxygen, and the second atomic percentage is less than the first atomic percentage; after the modification, the sacrificial layer is removed. When the atomic percentage of oxygen in the sacrificial layer is relatively low, it is advantageous to select an appropriate process. During the removal of the sacrificial layer, etching damage to the surface of the initial substrate and the mask layer located thereon is minimal, making removal of the sacrificial layer less difficult, thereby reducing process costs and time.

[0043] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0044] Figures 6 to 16 1 is a schematic structural diagram of each step of a method for forming a semiconductor structure in one embodiment of the present invention.

[0045] Provide an initial substrate, the initial substrate having a plurality of separate mask layers. For details on the process of forming the initial substrate and the mask layers, please refer to Figures 6 to 8.

[0046] Please refer to Figure 6 , providing an initial substrate 200.

[0047] In this embodiment, the initial base 200 includes an initial substrate 201 and a hard mask material layer 202 located on a surface of the initial substrate 201 .

[0048] The material of the initial substrate 201 is a semiconductor material. In this embodiment, the material of the initial substrate 201 is silicon. In other embodiments, the material of the initial substrate includes silicon carbide, silicon germanium, a multinary semiconductor material composed of Group III-V elements, silicon-on-insulator (SOI), or germanium-on-insulator. The multinary semiconductor material composed of Group III-V elements includes InP, GaAs, GaP, InAs, InSb, InGaAs, or InGaAsP.

[0049] The material of the hard mask material layer 202 includes silicon, silicon oxide, silicon nitride, titanium nitride, silicon oxynitride or silicon oxycarbide.

[0050] In this embodiment, the hard mask material layer 202 is a stacked structure, and the hard mask material layer 202 includes a first hard mask material film (not shown in the figure) and a second hard mask material film (not shown in the figure) located on the surface of the first hard mask material film; the material of the first hard mask material film is nitrogen-doped silicon oxycarbide, and the material of the second hard mask material film is silicon nitride.

[0051] The hard mask material layer 202 functions as an etching stop layer on the one hand; on the other hand, the material of the hard mask material layer 202 is a hard mask material, so the etching loss of the hard mask material layer 202 is small, which is conducive to improving the stability of pattern transfer.

[0052] In other embodiments, the hard mask material layer may also be a single-layer structure.

[0053] Please refer to Figure 7 , a plurality of mutually independent core layers 210 are formed on the initial substrate 200 .

[0054] The core layer 210 is used to provide support for the subsequent formation of a mask layer.

[0055] In this embodiment, the core layer 210 is located on the surface of the hard mask material layer 202 .

[0056] The core layer 210 may be made of silicon, silicon nitride, silicon oxide, amorphous carbon or optical resist.

[0057] In this embodiment, the core layer 210 is made of silicon.

[0058] Please refer to Figure 8 A mask material layer 220 is formed on the surface of the initial substrate 200, the top surface and the sidewall surface of the core layer 210.

[0059] The mask material layer 220 is used to provide material for subsequent formation of a mask layer.

[0060] In this embodiment, the mask material layer 220 is located on the surface of the hard mask material layer 202 and the top surface and sidewall surfaces of the core layer 210 .

[0061] In this embodiment, the mask material layer 220 and the core layer 210 are made of different materials, and the mask material layer 220 and the second hard mask material film are made of different materials.

[0062] The material of the mask material layer 220 includes silicon, silicon oxide, silicon nitride or titanium oxide.

[0063] In this embodiment, the mask material layer 220 is made of titanium nitride.

[0064] The process of forming the mask material layer 220 includes a chemical vapor deposition process, a physical vapor deposition process or an atomic layer deposition process.

[0065] Please refer to Figure 9 , the mask material layer 220 is etched back until the surface of the initial substrate 200 and the top surface of the core layer 210 are exposed, and a mask layer 230 is formed on the initial substrate 200 .

[0066] The mask layer 230 is used as a mask for subsequent etching of the initial substrate 200 .

[0067] The etching rate of the mask material layer 220 in the process of etching back the mask material layer 220 is greater than the etching rate of the initial substrate 200 , which is beneficial to the stability of the pattern transfer.

[0068] In this embodiment, the process of etching back the mask material layer 220 is an anisotropic dry etching process.

[0069] The mask layer 230 is formed by etching back the mask material layer 220 . Accordingly, the material of the mask layer 230 includes silicon, silicon oxide, silicon nitride, or titanium oxide.

[0070] In this embodiment, the material of the mask layer 230 is titanium nitride.

[0071] In this embodiment, after forming the mask layer 230, the process further includes removing the core layer 210. The etching rate of the core layer 210 during the process of removing the core layer 210 is higher than that of the initial substrate 200, which is beneficial to the stability of pattern transfer.

[0072] Please refer to Figure 10 After forming the mask layer 230 , a sacrificial film 240 is formed on the initial substrate 200 , wherein the sacrificial film 240 covers the sidewall surface and the top surface of the mask layer 230 , and the oxygen in the material of the sacrificial film 240 has a first atomic percentage.

[0073] The first atomic percentage ranges from 30% to 80%.

[0074] The material of the sacrificial film 240 is different from that of the mask layer 230 .

[0075] The material of the sacrificial film 240 also contains carbon.

[0076] The ratio of the number of oxygen atoms to the number of carbon atoms in the material of the sacrificial film 240 is in a range of 0.2:1 to 0.8:1.

[0077] In this embodiment, the process for forming the sacrificial film 240 is a physical vapor deposition process; the parameters of the physical vapor deposition process include: using graphite as a target material, the gas introduced includes: oxygen or argon, the gas flow rate is 20 standard ml / min to 200 standard ml / min, the pressure is 2 mTorr to 100 mTorr, and the DC power is 200 W to 800 W.

[0078] In this embodiment, the ratio of the number of atoms of oxygen element to the number of atoms of carbon element in the material of the sacrificial film 240 is 0.8:1. The material of the sacrificial film 240 is a-CO 0.8 . .

[0079] Next, a sacrificial opening is formed in the sacrificial film, and the bottom of the sacrificial opening exposes at least one top surface of the mask layer. For the specific process of forming the sacrificial opening, please refer to Figures 11 to 12 .

[0080] Please refer to Figure 11 A patterned layer 250 is formed on the surface of the sacrificial film 240 , and a patterned opening 251 is provided in the patterned layer 250 , and the position and size of the patterned opening 251 correspond to the position and size of the sacrificial opening.

[0081] The patterned layer 250 is used as a mask for subsequently etching the sacrificial film 240 to form a sacrificial opening.

[0082] The material of the patterned layer 250 includes: photoresist

[0083] The process of forming the patterned layer 250 includes: an exposure and development process.

[0084] In this embodiment, before forming the patterned layer 250 , the method further includes forming an anti-reflection layer (not shown in the figure) on the surface of the sacrificial film 240 .

[0085] The anti-reflection layer is used to reduce the reflection of light during the exposure process, thereby improving the accuracy of the formed patterned layer 250 .

[0086] In other embodiments, the anti-reflection layer may not be formed.

[0087] Please refer to Figure 12 , a second etching process is used to pattern the layer 250 (eg Figure 11 ) is a mask, and the sacrificial film 240 is etched until the top surface of the mask layer 230 is exposed, forming a sacrificial opening 241 in the sacrificial film 240.

[0088] The sacrificial film 240 is used as a mask for subsequent etching of the mask layer. Therefore, the position of the sacrificial opening 241 in the sacrificial film 240 corresponds to the position of the mask layer 230 to be removed subsequently.

[0089] The material of the sacrificial film 240 contains oxygen at a first atomic percentage, the material of the sacrificial film 240 contains a higher atomic percentage of oxygen, and the sacrificial film 240 also contains carbon. Because the bond energy of a CO bond is greater than that of a CC bond, a higher energy is required to break the CO bond. Therefore, the sacrificial film 240 has good etch resistance. Furthermore, during the second etching process to etch a portion of the sacrificial film 240, the sacrificial film 240 exhibits a better morphology after the sacrificial opening 241 is formed due to its good etch resistance. This improves the accuracy of pattern transfer, thereby improving the process window and resulting in better performance of the resulting semiconductor structure.

[0090] The etching rate of the patterned layer 250 by the second etching process is lower than the etching rate of the sacrificial film 240 .

[0091] In this embodiment, the second etching process is a dry etching process; the parameters of the dry etching process include: the etching gas used includes carbon monoxide, silicon dioxide, argon or sulfur dioxide, the gas flow rate is 100 standard ml / min to 500 standard ml / min, the temperature is 10 degrees Celsius to 60 degrees Celsius, the pressure is 4 mTorr to 50 mTorr, the source power is 100 watts to 800 watts, and the bias power is 0 watts to 200 watts.

[0092] In this embodiment, after forming the sacrificial opening 241 , the process further includes: removing the patterned layer 250 .

[0093] Please refer to Figure 13 After forming the sacrificial opening 241 , a first etching process is performed to etch the mask layer 230 using the sacrificial film 240 as a mask until the surface of the initial substrate 200 is exposed.

[0094] The first etching process includes: one or a combination of a dry etching process and a wet etching process.

[0095] The etching rate of the mask layer 230 in the first etching process is greater than the etching rate of the sacrificial film 240 .

[0096] In this embodiment, the etching rate of the mask layer 230 by the first etching process is greater than the etching rate of the second hard mask material film.

[0097] In this embodiment, the first etching process is a wet etching process; parameters of the wet etching process include: the etching solution used is dilute sulfuric acid.

[0098] Since the morphology of the sacrificial opening 241 in the sacrificial film 240 is good and the deviation from the designed layout is small, etching the mask layer 230 using the sacrificial film 240 as a mask is beneficial to improving the accuracy of pattern transfer, thereby improving the process window and making the performance of the formed semiconductor structure better.

[0099] Please refer to Figure 14 After the first etching process, the sacrificial film 240 is modified to form a sacrificial layer 242, and the oxygen in the material of the sacrificial layer 242 has a second atomic percentage, and the second atomic percentage is less than the first atomic percentage.

[0100] The sacrificial layer 242 is formed by modifying the sacrificial film 240 . The oxygen in the material of the sacrificial film 240 has a first atomic percentage, and the oxygen in the material of the sacrificial layer 242 has a second atomic percentage, which is smaller than the first atomic percentage.

[0101] In this embodiment, the first atomic percentage range is 30% to 80%, and the second atomic percentage range is 0% to 5%.

[0102] The modification process includes a rapid annealing process; the process parameters of the rapid annealing process include a temperature range of 100 degrees Celsius to 500 degrees Celsius and a time of 30 seconds to 300 seconds.

[0103] The significance of selecting the temperature range for the rapid annealing process is that: if the temperature is less than 100 degrees Celsius, the rapid annealing process with a lower temperature is not conducive to fully acting on the sacrificial film 240, causing the atoms in the sacrificial film 240 material to rearrange and fully release oxygen atoms, thereby ensuring that the sacrificial film 240 can be completely modified, and the difficulty of subsequently removing the sacrificial layer 242 cannot be fully reduced; if the temperature is greater than 500 degrees Celsius, the rapid annealing process with an excessively high temperature is likely to cause high temperature effects on the devices formed by the previous process in the semiconductor structure, thereby reducing the performance of the semiconductor structure.

[0104] In this embodiment, the material of the sacrificial film 240 is a-CO 0.8 The material of the modified sacrificial layer 242 is amorphous carbon.

[0105] The material of the sacrificial film 240 also contains carbon, that is, the sacrificial film 240 contains oxygen and carbon. When the sacrificial film 240 is subjected to rapid annealing, the atoms in the sacrificial film 240 are easily rearranged under high temperature conditions, and CC sp 2 bonds, thereby releasing oxygen atoms and forming amorphous carbon. Within a reasonable temperature range, as the temperature increases and the processing time increases, the rapid annealing process can fully modify the material of the sacrificial film 240. The rapid annealing process is simple and easy to operate. Therefore, using the rapid annealing process to form the sacrificial layer 242 can save process time. On the other hand, the ashing process can effectively remove amorphous carbon from the substrate, that is, it is conducive to the subsequent complete removal of the sacrificial layer 242. The ashing process is simple to operate and helps save process time.

[0106] Please refer to Figure 15 After the modification process, the sacrificial layer 242 is removed.

[0107] Since the atomic percentage of oxygen in the material of the sacrificial layer 242 is small, it is beneficial to select a suitable process. In the process of removing the sacrificial layer 242, the etching damage to the surface of the initial substrate 200 and the mask layer 230 located on the initial substrate 200 is small, making it less difficult to remove the sacrificial layer 242, which is beneficial to reducing process costs and saving process time.

[0108] The process of removing the sacrificial layer 242 includes a dry etching process, a wet etching process or an ashing process.

[0109] In this embodiment, the material of the sacrificial layer 242 is amorphous carbon. The sacrificial layer 242 can be removed by an ashing process. Parameters of the ashing process include: the gas used is an oxygen-containing gas, such as oxygen or ozone.

[0110] The ashing process effectively removes amorphous carbon from the substrate, that is, completely removes the sacrificial layer 242. On one hand, the ashing process is simple to operate, which helps save process time. On the other hand, the ashing process has minimal impact on the surface of the initial substrate 200 and the mask layer 230 located on the surface of the initial substrate 200. Therefore, while reducing the difficulty of removing the sacrificial layer 242, it also helps reduce process costs and save process time.

[0111] Please refer to Figure 16 After removing the sacrificial layer 242 , the initial substrate 200 is etched using the mask layer 230 as a mask to form a substrate 250 .

[0112] In this embodiment, the initial substrate 201 and the hard mask material layer 202 on the surface of the initial substrate 201 are etched to form a substrate 251 and a hard mask structure 252 on the surface of the substrate 251. The base 250 includes the substrate 251 and the hard mask structure 252.

[0113] Correspondingly, an embodiment of the present invention further provides a semiconductor structure formed by the above method.

[0114] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A method for forming a semiconductor structure, characterized in that: include: Providing an initial substrate, wherein the initial substrate has a plurality of separate mask layers; forming a sacrificial film on the initial substrate, the sacrificial film covering the sidewall surface and the top surface of the mask layer, wherein oxygen in the material of the sacrificial film has a first atomic percentage; forming a sacrificial opening in the sacrificial film, wherein a bottom of the sacrificial opening exposes at least one top surface of the mask layer; After forming the sacrificial opening, a first etching process is adopted to etch the mask layer using the sacrificial film as a mask until the initial substrate surface is exposed; After the first etching process, modifying the sacrificial film to form a sacrificial layer, wherein the oxygen in the material of the sacrificial layer has a second atomic percentage, and the second atomic percentage is less than the first atomic percentage; After the modification process, removing the sacrificial layer; The material of the sacrificial film also contains carbon element.

2. The method for forming a semiconductor structure according to claim 1, wherein: The first atomic percentage range is 30% to 80%; the second atomic percentage range is 0% to 5%.

3. The method for forming a semiconductor structure according to claim 2, wherein: The ratio of the number of oxygen atoms to the number of carbon atoms in the material of the sacrificial film is in a range of 0.2:1 to 0.8:

1.

4. The method for forming a semiconductor structure according to claim 3, wherein: The material of the sacrificial layer is amorphous carbon.

5. The method for forming a semiconductor structure according to claim 2, wherein: The process for forming the sacrificial film is a physical vapor deposition process; the parameters of the physical vapor deposition process include: using graphite as a target material, the gas introduced includes: oxygen or argon, the gas flow rate is 20 standard ml / min~200 standard ml / min, the pressure is 2 mTorr~100 mTorr, and the DC power is 200 W~800 W.

6. The method for forming a semiconductor structure according to claim 1, wherein: The modification process includes a rapid annealing process; the process parameters of the rapid annealing process include a temperature range of 100 degrees Celsius to 500 degrees Celsius and a time of 30 seconds to 300 seconds.

7. The method for forming a semiconductor structure according to claim 3, wherein: The material of the mask layer is different from that of the sacrificial film; the material of the mask layer includes silicon, silicon oxide, silicon nitride or titanium oxide.

8. The method for forming a semiconductor structure according to claim 1 or 7, wherein: The etching rate of the mask layer by the first etching process is greater than the etching rate of the sacrificial film; the first etching process is a wet etching process; The process parameters of the wet etching include: the etching solution used is dilute sulfuric acid.

9. The method for forming a semiconductor structure according to claim 1, wherein: The process of removing the sacrificial layer includes: a dry etching process, a wet etching process or an ashing process.

10. The method for forming a semiconductor structure according to claim 9, wherein: The process for removing the sacrificial layer is an ashing process; parameters of the ashing process include: the gas used is an oxygen-containing gas.

11. The method for forming a semiconductor structure according to claim 1, wherein: The method for forming the sacrificial opening includes: forming a patterned layer on the surface of the sacrificial film, the patterned layer having a patterned opening, and the position and size of the patterned opening correspond to the position and size of the sacrificial opening; using a second etching process, using the patterned layer as a mask, etching the sacrificial film until the top surface of the mask layer is exposed, thereby forming a sacrificial opening in the sacrificial film.

12. The method for forming a semiconductor structure according to claim 11, wherein: The second etching process is a dry etching process; the parameters of the dry etching process include: the etching gas used includes carbon monoxide, silicon dioxide, argon or sulfur dioxide, the gas flow rate is 100 standard ml / min~500 standard ml / min, the temperature is 10 degrees Celsius~60 degrees Celsius, the pressure is 4 mTorr~50 mTorr, the source power is 100 watts~800 watts, and the bias power is 0 watts~200 watts.

13. The method for forming a semiconductor structure according to claim 1, wherein: The method for forming the mask layer includes: forming a plurality of mutually discrete core layers on the initial substrate; forming a mask material layer on the surface of the initial substrate, the top surface of the core layer and the side wall surface; etching back the mask material layer until the surface of the initial substrate and the top surface of the core layer are exposed, thereby forming a mask layer on the initial substrate; after forming the mask layer, removing the core layer.

14. The method for forming a semiconductor structure according to claim 13, wherein: The material of the core layer includes silicon, silicon nitride, silicon oxide, amorphous carbon or optical resist.

15. The method for forming a semiconductor structure according to claim 1, wherein: The initial base comprises an initial substrate and a hard mask material layer located on the surface of the initial substrate.

16. The method for forming a semiconductor structure according to claim 15, wherein: The material of the hard mask material layer includes silicon, silicon oxide, silicon oxynitride or silicon oxycarbide.

17. The method for forming a semiconductor structure according to claim 1, wherein: Also includes: After removing the sacrificial layer, the initial substrate is etched using the mask layer as a mask to form a substrate.

18. A semiconductor structure formed by the method according to any one of claims 1 to 17.

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