Method for manufacturing a semiconductor structure

Abstract

The embodiments of the present disclosure relate to the field of semiconductors and provide a method for manufacturing a semiconductor structure, comprising: providing a substrate, on which a carbon-containing mask layer is formed; forming an initial mask layer on the carbon-containing mask layer, wherein the initial mask layer has a plurality of first openings; forming a carbon-containing sacrificial layer on a top surface of the initial mask layer, wherein the carbon-containing sacrificial layer has a plurality of second openings, wherein the second openings expose a portion of the top surface of the initial mask layer; using the carbon-containing sacrificial layer as a mask, etching the initial mask layer along the second openings to form a third opening penetrating the initial mask layer in the initial mask layer, with the remaining initial mask layer serving as a mask layer; in the same etching process, etching the carbon-containing mask layer along the third opening, and removing the carbon-containing sacrificial layer during the etching process to expose the first opening, and etching the carbon-containing mask layer along the first opening until a target opening penetrating the carbon-containing mask layer is formed in the carbon-containing mask layer, thereby simplifying the process of the entire method for manufacturing the semiconductor structure.

Description

Technical Field

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

[0002] Memory is a storage component used to store programs and various data. Random Access Memory (RAM) used in general computer systems can be divided into two types: Dynamic Random Access Memory (DRAM) and Static Random Access Memory (SRAM). DRAM is a commonly used semiconductor memory device in computers and is composed of many repeated storage cells.

[0003] Currently, mask etching is a common method in forming a memory. However, the process of forming the mask layer is relatively complicated. Summary of the Invention

[0004] The embodiments of the present disclosure provide a method for manufacturing a semiconductor structure, which can at least simplify the entire process of the method for manufacturing the semiconductor structure.

[0005] According to some embodiments of the present disclosure, on one hand, an embodiment of the present disclosure provides a method for manufacturing a semiconductor structure, comprising: providing a substrate, on which a carbon-containing mask layer is formed; forming an initial mask layer on the carbon-containing mask layer, wherein the initial mask layer has a plurality of first openings that penetrate the thickness of the initial mask layer and are arranged at intervals; forming a carbon-containing sacrificial layer on the top surface of the initial mask layer, wherein the carbon-containing sacrificial layer fills the first openings, and wherein the carbon-containing sacrificial layer has a plurality of second openings that penetrate the thickness of the carbon-containing sacrificial layer located on the top surface of the initial mask layer, wherein the second openings The opening exposes a portion of the top surface of the initial mask layer; using the carbon-containing sacrificial layer as a mask, the initial mask layer is etched along the second opening to form a third opening penetrating the initial mask layer in the initial mask layer, and the remaining initial mask layer serves as a mask layer; in the same etching process, the carbon-containing mask layer is etched along the third opening, and the carbon-containing sacrificial layer is removed during the etching process to expose the first opening, and the carbon-containing mask layer is etched along the first opening until a target opening penetrating the carbon-containing mask layer is formed in the carbon-containing mask layer.

[0006] In some embodiments, the etching process includes: a first etching step and a second etching step performed in sequence; the first etching step provides a first etching gas to etch the carbon-containing mask layer along the third opening and remove at least part of the thickness of the carbon-containing sacrificial layer; the second etching step provides a second etching gas and a protective gas, the second etching gas is used to etch the carbon-containing mask layer, and the protective gas is used to form a protective film on the side wall of the carbon-containing mask layer exposed by etching the carbon-containing mask layer along the third opening.

[0007] In some embodiments, the first etching gas is the same as the second etching gas, and after the first etching step is completed, the protective gas is introduced to perform the second etching step.

[0008] In some embodiments, the first etching step is used to completely remove the carbon-containing sacrificial layer, and when the carbon-containing sacrificial layer is completely removed, the second etching step is entered.

[0009] In some embodiments, the first etching step is used to etch the carbon-containing mask layer along the third opening until the target opening corresponding to the third opening is formed in the carbon-containing mask layer; when the target opening corresponding to the third opening is formed, the second etching step is entered.

[0010] In some embodiments, the gas flow rate of the protective gas provided in the second etching step is gradually increased.

[0011] In some embodiments, the first etching step further provides the protective gas, and the gas flow rate of the protective gas provided by the first etching step is smaller than the gas flow rate of the protective gas provided by the second etching step.

[0012] In some embodiments, the gas flow rate of the protective gas provided in the first etching step is 80 sccm to 110 sccm; the gas flow rate of the protective gas provided in the second etching step is 120 sccm to 150 sccm.

[0013] In some embodiments, the first etching gas includes oxygen; the second etching gas includes oxygen; and the protective gas includes carbon oxysulfide gas.

[0014] In some embodiments, before forming the initial mask layer, it also includes: forming a hard mask layer on the surface of the carbon-containing mask layer; wherein, before forming the initial mask layer on the surface of the hard mask layer; before etching the carbon-containing mask layer along the third opening, first etching the hard mask layer along the third opening.

[0015] In some embodiments, during etching of the hard mask layer along the third opening, a portion of the thickness of the carbon-containing sacrificial layer is consumed.

[0016] In some embodiments, after forming the initial mask layer and before forming the carbon-containing sacrificial layer, it also includes: etching the hard mask layer along the first opening to form a fourth opening in the hard mask layer that penetrates the thickness of the hard mask layer; wherein the formed carbon-containing sacrificial layer also fills the fourth opening; during the etching process, the carbon-containing sacrificial layer is removed and the fourth opening is exposed.

[0017] In some embodiments, before the etching process is performed, in a direction perpendicular to the surface of the substrate, the thickness of the carbon-containing mask layer is greater than or equal to the thickness of the carbon-containing sacrificial layer directly facing the first opening.

[0018] In some embodiments, before the etching process is performed, in a direction perpendicular to the substrate surface, the thickness of the carbon-containing mask layer is 90 nm to 110 nm, and the thickness of the carbon-containing sacrificial layer facing the first opening is 70 nm to 110 nm.

[0019] In some embodiments, an etching selectivity ratio of the etching process to the carbon-containing mask layer and the carbon-containing sacrificial layer is less than or equal to 2.

[0020] In some embodiments, the material of the carbon-containing mask layer includes amorphous carbon.

[0021] The technical solution provided by the embodiments of the present disclosure has at least the following advantages: by forming a carbon-containing mask layer on the surface of the substrate, a process basis is provided for subsequently forming a target opening on the carbon-containing mask layer; by sequentially forming an initial mask layer having a first opening and a carbon-containing sacrificial layer having a second opening, a process basis is provided for subsequently forming a mask layer having a third opening; by etching the carbon-containing mask layer along the third opening in the same etching process, and during the etching process, removing the carbon-containing sacrificial layer, and continuing to etch the carbon-containing mask layer along the first opening exposed after the carbon-containing sacrificial layer is removed, the carbon-containing mask layer is finally etched using the mask layer containing the first opening and the third opening as a mask to form a target opening on the carbon-containing mask layer, and the process steps for forming the target opening on the carbon-containing mask layer can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the traditional technology, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figures 1 to 8 A schematic structural diagram corresponding to each step of a method for manufacturing a semiconductor structure provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0024] As can be seen from the background technology, in the current process of forming a mask layer, a carbon-containing sacrificial layer with a second opening is first formed on the initial mask layer, and then the initial mask layer is etched using the carbon-containing sacrificial layer as a mask to form a mask layer with a first opening and a third opening. The carbon-containing sacrificial layer is then removed and a cleaning process is performed. Finally, the carbon-containing mask layer is etched using the mask layer as a mask to form a carbon-containing mask layer with a target opening.

[0025] An embodiment of the present disclosure provides a method for manufacturing a semiconductor structure, which provides a process basis for subsequently forming a target opening on the carbon-containing mask layer by forming a carbon-containing mask layer on the surface of a substrate, and provides a process basis for subsequently forming an initial mask layer having a first opening and a carbon-containing sacrificial layer having a second opening by sequentially forming a mask layer having a third opening. The carbon-containing mask layer is etched along the third opening in the same etching process, and during the etching process, the carbon-containing sacrificial layer is removed, and the carbon-containing mask layer is further etched along the first opening exposed after the carbon-containing sacrificial layer is removed, so that the carbon-containing mask layer is finally etched using the mask layer containing the first opening and the third opening as a mask to form a target opening on the carbon-containing mask layer, and the process steps for forming the target opening on the carbon-containing mask layer can be reduced.

[0026] The following describes various embodiments of the present disclosure in detail with reference to the accompanying drawings. However, those skilled in the art will appreciate that many technical details are provided in the various embodiments of the present disclosure to facilitate a better understanding of the present disclosure. However, even without these technical details and the various variations and modifications based on the following embodiments, the technical solutions claimed in the present disclosure can still be implemented.

[0027] refer to Figures 1 to 8 , Figures 1 to 8 A method for manufacturing a semiconductor structure is provided in one embodiment of the present disclosure.

[0028] In some embodiments, a method for fabricating a semiconductor structure includes providing a substrate 100 , on which a carbon-containing mask layer 110 is formed.

[0029] The method for manufacturing the semiconductor structure further includes forming an initial mask layer 121 on the carbon-containing mask layer 110 , wherein the initial mask layer 121 has a plurality of first openings 122 that penetrate the thickness of the initial mask layer 121 and are arranged at intervals.

[0030] The method for manufacturing the semiconductor structure also includes: forming a carbon-containing sacrificial layer 130 on the top surface of the initial mask layer 121, the carbon-containing sacrificial layer 130 fills the first opening 122, and the carbon-containing sacrificial layer 130 has a plurality of second openings 131 that penetrate the thickness of the carbon-containing sacrificial layer 130 located on the top surface of the initial mask layer 121, and the second openings 131 expose a portion of the top surface of the initial mask layer 121.

[0031] The method for manufacturing the semiconductor structure further includes: using the carbon-containing sacrificial layer 130 as a mask, etching the initial mask layer 121 along the second opening 131 to form a third opening 123 in the initial mask layer 121 that penetrates the initial mask layer 121 , and the remaining initial mask layer 121 serves as the mask layer 120 .

[0032] The method for manufacturing the semiconductor structure also includes: in the same etching process, etching the carbon-containing mask layer 110 along the third opening 123, and removing the carbon-containing sacrificial layer 130 during the etching process to expose the first opening 122, and etching the carbon-containing mask layer 110 along the first opening 122 until a target opening 111 is formed in the carbon-containing mask layer 110 and penetrates the carbon-containing mask layer 110.

[0033] By forming a carbon-containing mask layer 110 on the surface of the substrate 100, a process basis is provided for subsequently forming a target opening 111 on the carbon-containing mask layer 110. By sequentially forming an initial mask layer 121 having a first opening 122 and a carbon-containing sacrificial layer 130 having a second opening 131, a process basis is provided for subsequently forming a mask layer 120 having a third opening 123. By etching the carbon-containing mask layer 110 along the third opening 123 in the same etching process, and removing the carbon-containing sacrificial layer 130 during the etching process, and continuing to etch the carbon-containing mask layer 110 along the first opening 122 exposed after the carbon-containing sacrificial layer 130 is removed, the carbon-containing mask layer 110 is finally etched using the mask layer 120 containing the first opening 122 and the third opening 123 as a mask to form the target opening 111 on the carbon-containing mask layer 110, and the process steps for forming the target opening 111 on the carbon-containing mask layer 110 can be reduced.

[0034] refer to Figure 1In some embodiments, the material of substrate 100 may include a semiconductor material, such as, but not limited to, silicon. In some embodiments, the material of substrate 100 may include germanium, silicon carbide, gallium arsenide, gallium phosphide, indium phosphide, indium arsenide, indium antimonide, and / or Group III-V semiconductor materials. The material of substrate 100 may also include silicon germanium, silicon germanium carbide, germanium tin, silicon germanium tin, gallium arsenic phosphide, gallium indium phosphide, gallium indium arsenide, indium gallium arsenide phosphide, aluminum indium arsenide, and / or aluminum gallium arsenide. In some embodiments, substrate 100 may also be a silicon-on-insulator structure, a silicon-germanium-on-insulator structure, a germanium-on-insulator structure, or a combination thereof.

[0035] In addition, the substrate 100 can be doped according to design requirements (e.g., a P-type substrate or an N-type substrate). In some embodiments, the substrate 100 can be doped with P-type dopant ions (e.g., boron ions, aluminum ions) or N-type dopant ions (e.g., phosphorus ions, arsenic ions).

[0036] In some embodiments, the material of the carbon-containing mask layer 110 may include amorphous carbon. By using amorphous carbon as the material of the carbon-containing mask layer 110, the etching selectivity between the carbon-containing mask layer 110 and the carbon-containing sacrificial layer 130 does not differ significantly. As a result, the carbon-containing mask layer 110 and the carbon-containing sacrificial layer 130 can be etched in the same step, thereby reducing the number of process steps in the semiconductor structure fabrication method.

[0037] In some embodiments, before forming the initial mask layer 121, the process further includes forming a hard mask layer 140 on the surface of the carbon-containing mask layer 110; wherein the initial mask layer 121 is formed on the surface of the hard mask layer 140. The hard mask layer 140 can serve as an etch stop layer for subsequently etching the initial mask layer 121 to form the third opening 123 on the initial mask layer 121, thereby preventing over-etching during the process of forming the third opening 123.

[0038] In some embodiments, before etching the carbon-containing mask layer 110 along the third opening 123, the hard mask layer 140 is first etched along the third opening 123. It can be understood that the etching selectivity of the hard mask layer 140 and the carbon-containing mask layer 110 is relatively large. Therefore, by etching the hard mask layer 140 along the third opening 123 first, the rate of forming the target opening on the carbon-containing mask layer can be accelerated.

[0039] In some embodiments, a portion of the carbon-containing sacrificial layer 130 is consumed during the etching of the hard mask layer 140 along the third opening 123. In other words, a portion of the carbon-containing sacrificial layer 130 is also etched during the etching of the hard mask layer 140 along the third opening 123, thereby reducing the process time required to subsequently expose the first opening 122 and reducing the difference in etching starting points between etching the carbon-containing mask layer 110 corresponding to the first opening 122 and etching the carbon-containing mask layer 110 corresponding to the third opening 123, thereby improving the reliability of the semiconductor structure manufacturing method.

[0040] In some embodiments, the hard mask layer may also be etched along the third opening 123 when the carbon-containing mask layer 110 needs to be etched later.

[0041] refer to Figure 2 and Figure 3 In some embodiments, after forming the initial mask layer 121 and before forming the carbon-containing sacrificial layer 130, the process further includes: etching the hard mask layer 140 along the first opening 122 to form a fourth opening 141 in the hard mask layer 140 that penetrates the thickness of the hard mask layer 140; wherein the formed carbon-containing sacrificial layer 130 also fills the fourth opening 141; during the etching process, the carbon-containing sacrificial layer 130 is removed, and the fourth opening 141 is exposed.

[0042] It can be understood that in the entire etching process, the entire etching process is as follows: etching the hard mask layer 140 along the third opening 123, etching the carbon-containing mask layer 110 only after the hard mask layer 140 corresponding to the third opening 123 is etched, and in the process of etching the hard mask layer 140, etching the carbon-containing sacrificial layer 130 that fills the first opening 122, and after the etching of the carbon-containing sacrificial layer 130 is completed, etching the hard mask layer 140 exposed by the first opening 122, and when the etching of the hard mask layer 140 exposed by the first opening 122 is completed, etching the carbon-containing mask layer 110 corresponding to the first opening 122 is started. Moreover, compared with the carbon-containing mask layer 110 and the carbon-containing sacrificial layer 130, the hard mask layer 140 is more difficult to etch. In order to avoid excessively prolonging the entire etching process, the embodiment of the present disclosure can first etch the hard mask layer 140 along the third opening before etching the carbon-containing mask layer 110 along the third opening 123, thereby reducing the time wasted in etching the hard mask layer 140, and before forming the carbon-containing sacrificial layer 130, first etch away the hard mask layer 140 exposed by the first opening 122, thereby avoiding the need to etch the hard mask layer 140 in the subsequent etching process, thereby avoiding prolonging the duration of the entire etching process.

[0043] In some embodiments, the hard mask layer 140 may be etched along the first openings before the carbon-containing sacrificial layer 110 is formed, rather than etching the hard mask layer 140 along the third openings 123. It is understood that during the etching process, the first openings 122 and the third openings 123 have different etching starting points corresponding to the carbon-containing mask layer 110. The third openings 123 begin etching the carbon-containing mask layer 110 after etching the hard mask layer 140, while the first openings 122 require that the carbon-containing sacrificial layer 130 be removed before etching the hard mask layer 140 and then etching the carbon-containing mask layer 110. Consequently, when etching of the carbon-containing mask layer 110 begins at the locations corresponding to the third openings 123, etching of the carbon-containing sacrificial layer 130 or the hard mask layer 140 is still ongoing at the locations corresponding to the first openings 122. Therefore, by setting it as before etching the carbon-containing mask layer 110 along the third opening 123, the hard mask layer 140 is not etched along the third opening 123, and before forming the carbon-containing sacrificial layer, the hard mask layer 140 is etched along the first opening, so that the carbon-containing sacrificial layer 130 at the corresponding position of the first opening 122 is consumed in the process of etching the hard mask layer 140 along the third opening 123. Since the carbon-containing sacrificial layer 130 is easier to be etched than the hard mask layer 140, it is possible to At this time, more of the carbon-containing sacrificial layer 130 at the position corresponding to the first opening 122 can be removed, and even the carbon-containing sacrificial layer 130 can be etched clean, thereby reducing the difference between the moment when the carbon-containing mask layer 110 starts to be etched at the position of the first opening 122 and the moment when the carbon-containing mask layer 110 starts to be etched at the position of the third opening 123, so that the difference between the moment when the carbon-containing mask layer 110 is etched through along the first opening 122 and the moment when the carbon-containing mask layer 110 is etched through along the third opening 123 can be smaller, thereby improving the reliability of the target opening formed.

[0044] In some embodiments, the material of the hard mask layer 140 may be silicon nitride or silicon oxynitride.

[0045] In some embodiments, the method of forming the initial mask layer 121 having the first opening 122 may include: forming a photoresist layer having the first opening, and then etching the initial mask layer 121 using the photoresist layer as a mask.

[0046] refer to Figures 3 to 6In some embodiments, the method of forming the carbon-containing sacrificial layer 130 having a plurality of second openings 131 may include: first forming a carbon-containing sacrificial layer 130 that fills the first openings, then forming a sacrificial layer 150 having a fifth opening 151 on a top surface of the first opening, forming a sidewall layer 160 that conformally covers the fifth opening 151, and forming a filling layer 170 that fills the fifth opening, removing the sidewall layer 160 located on the sidewall of the sacrificial layer 150 to form a sixth opening 161, and etching through the carbon-containing sacrificial layer 130 along the sixth opening 161 to form a carbon-containing sacrificial layer 130 having the second openings 131.

[0047] In some embodiments, after forming the carbon-containing sacrificial layer 130 , the sacrificial layer 150 , the spacer layer 160 , and the filling layer 170 may be removed.

[0048] In some embodiments, the carbon-containing sacrificial layer 130 may be formed by spin-coating a hard mask layer.

[0049] In some embodiments, the material of the sacrificial layer 150 may be the same as that of the carbon-containing sacrificial layer 130 , and the material of the filling layer 170 may also be the same as that of the sacrificial layer 150 .

[0050] In some embodiments, the material of the spacer layer 160 can be silicon oxide or the like.

[0051] refer to Figure 7 The initial mask layer 121 is etched using the carbon-containing sacrificial layer 130 as a mask to form the mask layer 120 having the third opening 123 .

[0052] refer to Figure 8 , an etching process is performed to form a carbon-containing mask layer 110 having a target opening 111 .

[0053] In some embodiments, the etching process may include: a first etching step and a second etching step performed sequentially; in the first etching step, a first etching gas is provided to etch the carbon-containing mask layer 110 along the third opening 123 and remove at least a portion of the carbon-containing sacrificial layer 130; in the second etching step, a second etching gas and a protective gas are provided, wherein the second etching gas is used to etch the carbon-containing mask layer 110, and the protective gas is used to form a protective film on the sidewalls of the carbon-containing mask layer 110 exposed by etching the carbon-containing mask layer 110 along the third opening 123. It is understood that the first etching step etches the carbon-containing mask layer 110 at a relatively fast rate and also removes at least a portion of the carbon-containing sacrificial layer 130 during the etching process, thereby facilitating subsequent etching of the carbon-containing mask layer 110 along the first opening 122. In the second etching step, the protective gas is provided to prevent lateral etching during the etching process, thereby preventing the size of the target opening formed from being significantly different from the desired size, and ensuring the accuracy of the target opening.

[0054] In some embodiments, a protective gas may be introduced throughout the entire etching process. It is understandable that although the protective gas may form a protective film on the sidewalls of the carbon-containing mask layer 110, the formed protective film may also affect the etching rate of the carbon-containing mask layer 110. Therefore, only the first etching gas is introduced in the first etching step, and the protective gas and etching gas are introduced in the second etching step to speed up the rate of the entire etching process.

[0055] In some embodiments, the first etching gas and the second etching gas are the same. After the first etching step is completed, a protective gas is introduced to perform the second etching step. In other words, the first etching step and the second etching step can be completed in the same etching chamber, and the transition from the first etching step to the second etching step can be completed by adjusting the gas, thereby simplifying the semiconductor structure manufacturing method.

[0056] In some embodiments, the first etching step is used to completely remove the carbon-containing sacrificial layer 130. When the carbon-containing sacrificial layer 130 is completely removed, the second etching step is entered. The carbon-containing sacrificial layer 130 can be removed faster through the first etching step, thereby exposing the first opening 122 faster, and the carbon-containing mask layer 110 can be etched along the first opening 122. By entering the second etching step after removing the carbon-containing sacrificial layer 130, the etching rate of the etching process can be increased while protecting the opening size of the formed target opening 111 to the expected size.

[0057] In some embodiments, a first etching step is used to etch the carbon-containing mask layer 110 along the third opening 123 until a target opening 111 corresponding to the third opening 123 is formed in the carbon-containing mask layer 110. When the target opening 111 corresponding to the third opening 123 is formed, the second etching step is entered. It is understood that, since the first and third openings 122 and 123 etch the carbon-containing mask layer 110 from different starting points during the entire etching process, the first opening 122 must first etch the carbon-containing sacrificial layer 130 before etching the carbon-containing mask layer 110. Therefore, there may be a problem where the third opening 123 has already formed the target opening 111 while the first opening 122 is still etching the carbon-containing mask layer 110. The use of a protective gas can prevent the target opening 111 corresponding to the third opening 123 from being laterally etched. Entering the second etching step when the target opening 111 corresponding to the third opening 123 is formed can increase the etching rate of the entire etching process.

[0058] In some embodiments, the gas flow rate of the protective gas provided in the second etching step gradually increases. It can be understood that as the etching process proceeds, the depth of the etched carbon-containing mask layer 110 becomes deeper, and the bottom of the target opening 111 formed needs to be more protected than the top of the target opening 111. Therefore, by setting the gas flow rate of the protective gas provided in the second etching step to gradually increase, the reliability of the semiconductor structure manufacturing method can be improved.

[0059] It should be noted that the bottom of the target opening 111 here refers to the portion of the target opening 111 close to the substrate 100 , and the top of the target opening 111 refers to the portion of the target opening 111 away from the substrate 100 .

[0060] In some embodiments, a protective gas is also provided during the first etching step, and the flow rate of the protective gas provided during the first etching step is less than the flow rate of the protective gas provided during the second etching step. By also providing the protective gas during the first etching step, a protective film can be formed on the sidewalls of the carbon-containing mask layer 110 while etching the carbon-containing mask layer 110 during the first etching step, thereby improving the accuracy of the target opening 111 formed.

[0061] In some embodiments, the first etching step further etches a portion of the carbon-containing mask layer 110 corresponding to the first opening 122 .

[0062] In some embodiments, in the first etching step, the gas flow ratio of the first etching gas to the shielding gas is a first ratio; in the second etching step, the gas flow ratio of the second etching gas to the shielding gas is a second ratio; wherein the first ratio is greater than the second ratio. In other words, in the first etching step, the first etching gas is relatively more abundant, while in the second etching step, the shielding gas is relatively more abundant. Compared to the first etching step, the second etching step corresponds to the bottom of the target opening 111, and the bottom of the target opening 111 needs to be more protected. Therefore, by setting the first ratio to be greater than the second ratio, the accuracy of the target opening 111 can be improved.

[0063] It should be noted that in the above, the first etching gas is relatively more, which does not limit the gas flow rate of the first etching gas to be relatively more, but refers to the proportion of the first etching gas to the gas introduced in the entire first etching step in the first etching step, and this relatively more means that the proportion of the first etching gas to the gas introduced in the entire first etching step is more than the proportion of the second etching gas to the gas introduced in the entire second etching step.

[0064] In some embodiments, the gas flow rate of the first etching gas may be greater than the gas flow rate of the second etching gas, and the gas flow rate of the first etching gas may also be less than or equal to the gas flow rate of the second etching gas; the gas flow rate of the protective gas introduced in the first etching step may be greater than the gas flow rate of the protective gas introduced in the second etching step, and the gas flow rate of the protective gas introduced in the first etching step may also be less than or equal to the gas flow rate of the protective gas introduced in the second etching step.

[0065] In some embodiments, the gas flow rate of the protective gas provided in the first etching step is 80 sccm to 110 sccm, for example, 90 sccm, 95 sccm, 100 sccm or 105 sccm, etc.; the gas flow rate of the protective gas provided in the second etching step is 120 sccm to 150 sccm, for example, 130 sccm, 135 sccm, 140 sccm or 145 sccm, etc. It can be understood that the greater the gas flow rate of the protective gas, the stronger the protective ability, and the greater the gas flow rate of the protective gas, the slower the etching rate of the entire etching process. Therefore, by setting the gas flow rate of the protective gas provided in the first etching step to 80sccm~110sccm and the gas flow rate of the protective gas provided in the second etching step to 120sccm~150sccm, the etching rate of the first etching step can be made faster than the etching rate of the second etching step, and the protective effect of the second etching step in protecting the carbon-containing mask layer 110 is better than the protective effect of the first etching step in protecting the carbon-containing mask layer 110, so that the side wall of the carbon-containing mask layer 110 can be well protected and the opening size of the target opening can be ensured, and the entire etching process can have a certain etching rate, thereby reducing the etching time required for the entire etching process.

[0066] In some embodiments, the first etching gas includes oxygen; the second etching gas includes oxygen; and the protective gas includes carbon oxysulfide (COS) gas. Oxygen can etch carbon-containing materials faster, that is, oxygen can effectively etch the carbon-containing mask layer 110 and the carbon-containing sacrificial layer 130. The carbon oxysulfide gas can separate sulfur active ions and combine with carbon in the carbon-containing mask layer 110 to form a protective film on the sidewalls of the carbon-containing mask layer 110, thereby preventing the etching process from lateral etching of the carbon-containing mask layer 110 exposed along the target opening 111.

[0067] In some embodiments, before the etching process is performed, the thickness of the carbon-containing mask layer 110 in a direction perpendicular to the surface of the substrate 100 is greater than or equal to the thickness of the carbon-containing sacrificial layer 130 directly opposite the first opening 122. It is understood that during the etching process, when the carbon-containing mask layer 110 is first etched at the position corresponding to the third opening 123, the first opening 122 may still be etching the carbon-containing sacrificial layer 130. Therefore, by setting the thickness of the carbon-containing mask layer 110 to be greater than or equal to the thickness of the carbon-containing sacrificial layer 130 directly opposite the first opening 122, the carbon-containing mask layer 110 can be completely etched before the position corresponding to the third opening 123 is completely etched, or when the carbon-containing sacrificial layer 130 is just completely etched, thereby starting to etch the carbon-containing mask layer 110 along the first opening 122. This can reduce lateral etching of the target opening 111 corresponding to the third opening 123, thereby improving the reliability of the formed target opening 111.

[0068] In some embodiments, before the etching process is performed, the thickness of the carbon-containing mask layer 110 in a direction perpendicular to the surface of the substrate 100 is 90 nm to 110 nm, for example, 95 nm, 100 nm, or 105 nm, etc., and the thickness of the carbon-containing sacrificial layer 130 opposite the first opening 122 is 70 nm to 110 nm, for example, 80 nm, 90 nm, 100 nm, or 105 nm, etc. It can be understood that the thicker the carbon-containing mask layer 110 is, the easier it is to form the target opening 111. However, the thicker the carbon-containing mask layer 110 is, the longer it takes to etch the carbon-containing mask layer 110. The thicker the carbon-containing sacrificial layer 130 is, the easier it is to improve the accuracy of the second opening 131 formed, thereby improving the accuracy of forming the third opening 123. Therefore, by setting the thickness of the carbon-containing mask layer 110 to 90nm~110nm and the thickness of the carbon-containing sacrificial layer 130 facing the first opening 122 to 70nm~110nm, the accuracy of the target opening 111 formed can be improved, and the mask can be improved. The accuracy of the third opening 123 on the layer 120 is improved, thereby improving the accuracy of the formed target opening 111. Secondly, by setting the thickness of the carbon-containing sacrificial layer 130 facing the first opening 122 to 70nm~110nm, the carbon-containing sacrificial layer 130 can be etched clean before the carbon-containing mask layer 110 is completely etched at the position corresponding to the third opening 123, or just after being etched, so that the carbon-containing mask layer 110 starts to be etched along the first opening 122, thereby reducing the lateral etching of the target opening 111 corresponding to the third opening 123, thereby improving the reliability of the formed target opening 111.

[0069] If the thickness of the carbon-containing mask layer is less than 90 nm, the size of the target opening 111 may not be accurate enough. If the thickness of the carbon-containing mask layer is greater than 110 nm, the etching process may take too long, affecting the process time of the entire semiconductor structure manufacturing method. If the thickness of the carbon-containing sacrificial layer 130 directly opposite the first opening 122 is less than 70 nm, the thickness of the carbon-containing sacrificial layer 130 at the position corresponding to the second opening 131 is also less, affecting the accuracy of the second opening 131, which in turn may affect the accuracy of the third opening 123 formed on the mask layer 120, and ultimately affect the accuracy of the target opening 111. If the thickness of the carbon-containing sacrificial layer 130 directly opposite the first opening 122 is greater than 110 nm, the target opening 111 corresponding to the third opening 123 may have been formed, but the first opening 122 is still being etched to remove the carbon-containing sacrificial layer 130, resulting in lateral etching of the target opening 111 corresponding to the third opening 123, resulting in an inaccurate target opening 111.

[0070] In some embodiments, the etching process has an etching selectivity ratio of the carbon-containing mask layer 110 to the carbon-containing sacrificial layer 130 that is less than or equal to 2. It can be understood that the smaller the etching selectivity ratio of the carbon-containing mask layer 110 to the carbon-containing sacrificial layer 130, the greater the thickness of the etched carbon-containing sacrificial layer 130 compared to the thickness of the etched carbon-containing mask layer 110 within the same time. By setting the etching process to have an etching selectivity ratio of the carbon-containing mask layer 110 to the carbon-containing sacrificial layer 130 that is less than or equal to 2, the carbon-containing sacrificial layer 130 corresponding to the first opening 122 can be removed more quickly, so that the difference between the moment when the carbon-containing mask layer 110 corresponding to the first opening 122 starts to be etched and the moment when the carbon-containing mask layer 110 corresponding to the third opening 123 starts to be etched will not be too large, thereby avoiding lateral etching in the target opening 111 corresponding to the third opening 123, and improving the reliability of the semiconductor structure manufacturing method.

[0071] In some embodiments, the etching process has an etching selectivity ratio of the carbon-containing mask layer 110 to the carbon-containing sacrificial layer 130 that is greater than or equal to 1 and less than or equal to 2, and the thickness of the carbon-containing sacrificial layer 130 may also be less than the thickness of the carbon-containing mask layer 110, thereby avoiding that, after the target opening 111 corresponding to the third opening 123 is formed, the carbon-containing sacrificial layer 130 is still being etched at the position corresponding to the first opening 122, thereby reducing lateral etching of the target opening 111 at the position corresponding to the third opening 123.

[0072] In some embodiments, a cleaning process may be performed after the etching process. The cleaning process may remove carbon-based impurities formed by etching the carbon-containing mask layer, thereby improving the reliability of the entire semiconductor structure manufacturing method.

[0073] In some embodiments, compared with related technologies, the embodiments of the present disclosure also reduce the number of cleaning processes. In related technologies, the carbon-containing sacrificial layer is first removed, then cleaning is performed, and then etching is performed. The embodiments of the present disclosure can also reduce the number of cleaning processes.

[0074] In some embodiments, oxygen and nitrogen fluoride gases may be introduced during the cleaning process to remove carbon-based impurities through oxygen and fluorine plasma, thereby reducing impurities in the target opening 111 and improving the cleanliness of the target opening 111 .

[0075] It should be noted that the above embodiments can be freely combined and are still within the protection scope of the embodiments of the present disclosure.

[0076] The embodiment of the present disclosure forms a carbon-containing mask layer 110 on the surface of the substrate 100, thereby providing a process basis for subsequently forming a target opening 111 on the carbon-containing mask layer 110. An initial mask layer 121 having a first opening 122 and a carbon-containing sacrificial layer 130 having a second opening 131 are sequentially formed to provide a process basis for subsequently forming a mask layer 120 having a third opening 123. The carbon-containing mask layer 110 is etched along the third opening 123 in the same etching process, and the carbon-containing sacrificial layer 130 is removed during the etching process. The carbon-containing mask layer 110 is further etched along the first opening 122 exposed after the carbon-containing sacrificial layer 130 is removed. Finally, the carbon-containing mask layer 110 is etched using the mask layer 120 containing the first opening 122 and the third opening 123 as a mask to form the target opening 111 on the carbon-containing mask layer 110, and the process steps for forming the target opening 111 on the carbon-containing mask layer 110 can be reduced.

[0077] Those skilled in the art will appreciate that the above-described embodiments are specific examples for implementing the present disclosure, and in actual applications, various changes may be made to them in form and detail without departing from the spirit and scope of the embodiments of the present disclosure. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the embodiments of the present disclosure. Therefore, the scope of protection of the embodiments of the present disclosure shall be based on the scope defined in the claims.

Claims

1. A method for manufacturing a semiconductor structure, characterized in that: include: providing a substrate, wherein a carbon-containing mask layer is formed on the substrate; forming an initial mask layer on the carbon-containing mask layer, wherein the initial mask layer has a plurality of first openings penetrating the thickness of the initial mask layer and arranged at intervals; forming a carbon-containing sacrificial layer on the top surface of the initial mask layer, wherein the carbon-containing sacrificial layer completely fills the first opening, and wherein the carbon-containing sacrificial layer has a plurality of second openings extending through the thickness of the carbon-containing sacrificial layer on the top surface of the initial mask layer, wherein the second openings expose a portion of the top surface of the initial mask layer; Using the carbon-containing sacrificial layer as a mask, etching the initial mask layer along the second opening to form a third opening in the initial mask layer that penetrates the initial mask layer, with the remaining initial mask layer serving as a mask layer; In the same etching process, the carbon-containing mask layer is etched along the third opening, and the carbon-containing sacrificial layer is removed during the etching process to expose the first opening, and the carbon-containing mask layer is etched along the first opening until a target opening is formed in the carbon-containing mask layer that penetrates the carbon-containing mask layer.

2. The method for manufacturing a semiconductor structure according to claim 1, wherein: The etching process includes: A first etching step and a second etching step are performed sequentially; The first etching step provides a first etching gas to etch the carbon-containing mask layer along the third opening and remove at least a portion of the thickness of the carbon-containing sacrificial layer; The second etching step provides a second etching gas and a protective gas, wherein the second etching gas is used to etch the carbon-containing mask layer, and the protective gas is used to form a protective film on the sidewalls of the carbon-containing mask layer exposed by etching the carbon-containing mask layer along the third opening.

3. The method for manufacturing a semiconductor structure according to claim 2, wherein: The first etching gas is the same as the second etching gas. After the first etching step is completed, the protective gas is introduced to perform the second etching step.

4. The method for manufacturing a semiconductor structure according to claim 2, wherein: The first etching step is used to completely remove the carbon-containing sacrificial layer. When the carbon-containing sacrificial layer is completely removed, the second etching step is entered.

5. The method for manufacturing a semiconductor structure according to claim 2, wherein: The first etching step is used to etch the carbon-containing mask layer along the third opening until the target opening corresponding to the third opening is formed in the carbon-containing mask layer; when the target opening corresponding to the third opening is formed, the second etching step is entered.

6. The method for manufacturing a semiconductor structure according to claim 2, wherein: The gas flow rate of the protective gas provided in the second etching step is gradually increased.

7. The method for manufacturing a semiconductor structure according to claim 2, wherein: The first etching step further provides the protective gas, and the gas flow rate of the protective gas provided in the first etching step is smaller than the gas flow rate of the protective gas provided in the second etching step.

8. The method for manufacturing a semiconductor structure according to claim 7, wherein: The gas flow rate of the protective gas provided in the first etching step is 80 sccm to 110 sccm; the gas flow rate of the protective gas provided in the second etching step is 120 sccm to 150 sccm.

9. The method for manufacturing a semiconductor structure according to claim 2, wherein: The first etching gas includes oxygen; the second etching gas includes oxygen; and the protective gas includes carbon oxysulfide gas.

10. The method for manufacturing a semiconductor structure according to claim 1, wherein: Before forming the initial mask layer, the method further includes: forming a hard mask layer on the surface of the carbon-containing mask layer; Wherein, the initial mask layer is formed on the surface of the hard mask layer; Before etching the carbon-containing mask layer along the third opening, the hard mask layer is first etched along the third opening.

11. The method for manufacturing a semiconductor structure according to claim 10, wherein: After forming the initial mask layer and before forming the carbon-containing sacrificial layer, the method further includes: Etching the hard mask layer along the first opening to form a fourth opening in the hard mask layer that penetrates the thickness of the hard mask layer; Wherein, the formed carbon-containing sacrificial layer also fills the fourth opening; During the etching process, the carbon-containing sacrificial layer is removed, and the fourth opening is exposed.

12. The method for manufacturing a semiconductor structure according to any one of claims 1 to 11, wherein: Before the etching process is performed, in a direction perpendicular to the surface of the substrate, the thickness of the carbon-containing mask layer is greater than or equal to the thickness of the carbon-containing sacrificial layer directly facing the first opening.

13. The method for manufacturing a semiconductor structure according to claim 12, wherein: Before the etching process is performed, in a direction perpendicular to the surface of the substrate, the thickness of the carbon-containing mask layer is 90 nm to 110 nm, and the thickness of the carbon-containing sacrificial layer facing the first opening is 70 nm to 110 nm.

14. The method for manufacturing a semiconductor structure according to any one of claims 1 to 10, characterized in that: The etching process has an etching selectivity ratio of the carbon-containing mask layer to the carbon-containing sacrificial layer that is less than or equal to 2.

15. The method for manufacturing a semiconductor structure according to claim 1, wherein: The material of the carbon-containing mask layer includes: amorphous carbon.

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