Manufacturing method of semiconductor structure

Abstract

The invention provides a manufacturing method of a semiconductor structure, relates to the technical field of semiconductors, and is used for solving the technical problem that an active region is easy to incline. The manufacturing method of the semiconductor structure comprises the following steps: forming a sacrificial structure on a substrate; the sacrificial structure and the substrate are etched, a plurality of active areas arranged at intervals are formed in the substrate, etching by-products exist between the adjacent active areas, and bosses correspondingly arranged on the active areas are formed on the sacrificial structure; etching by-products are removed through wet etching, partial areas, away from the substrate, of the adjacent bosses make contact and adhere to each other, and the active areas correspondingly connected with the bosses are spaced and are in an inclined state; and removing the bosses, releasing the inclined state of each active region, and recovering to be upright. The active areas are arranged at intervals, diffusion of reaction gas and reaction with the bosses are facilitated, the bosses are completely removed, the situation that the active areas are still kept in an inclined state due to adhesion of the remaining bosses is avoided, and inclination of the active areas is avoided.

Description

Technical Field

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

[0002] With the development of semiconductor technology, there are more and more types of semiconductor structures and their applications are becoming more and more extensive. For example, dynamic random access memory (DRAM) is widely used in various electronic devices because of its high storage density and fast read and write speed. The semiconductor structure includes a substrate, and a plurality of active areas (AA) are formed in the substrate. However, the active area is prone to tilt during the subsequent wet etching and cleaning process, and it is not easy to recover. Summary of the invention

[0003] In view of the above problems, an embodiment of the present disclosure provides a method for manufacturing a semiconductor structure to reduce the inclination of an active region.

[0004] According to some embodiments, the present disclosure provides a method for manufacturing a semiconductor structure, which includes:

[0005] forming a sacrificial structure on the substrate;

[0006] Etching the sacrificial structure and the substrate, forming a plurality of active areas spaced apart from each other in the substrate, with etching byproducts between adjacent active areas, and forming a boss corresponding to each active area on the sacrificial structure;

[0007] Wet etching is performed to remove the etching byproducts, so that the adjacent bosses are in contact and adhere to each other at partial regions away from the substrate, and the active regions corresponding to the bosses are spaced apart and in an inclined state;

[0008] By removing the bosses, each active area is freed from the tilted state and restored to an upright state.

[0009] In some possible embodiments, forming the sacrificial structure on the substrate includes: forming at least two sacrificial layers stacked in sequence on the substrate, the at least two sacrificial layers forming the sacrificial structure;

[0010] Etching the sacrificial structure and the substrate includes: etching each of the sacrificial layers and the substrate to form the active area and the boss, wherein the boss includes at least two layers, and the number of the layers is less than or equal to the number of the sacrificial layers, and each of the layers corresponds to one sacrificial layer.

[0011] In some possible embodiments, forming the sacrificial structure on the substrate includes:

[0012] forming a first sacrificial layer on the substrate, forming a second sacrificial layer on the first sacrificial layer, and forming a third sacrificial layer on the second sacrificial layer, wherein the third sacrificial layer, the second sacrificial layer and the first sacrificial layer form the sacrificial structure;

[0013] Etching the sacrificial structure and the substrate, comprising:

[0014] The third sacrificial layer, part of the second sacrificial layer, part of the first sacrificial layer and part of the substrate are etched away to form the active area and the boss, wherein the boss includes a first layer and a second layer, the first layer includes the remaining first sacrificial layer, and the second layer includes the remaining second sacrificial layer.

[0015] In some possible embodiments, etching and removing the third sacrificial layer, a portion of the second sacrificial layer, a portion of the first sacrificial layer, and a portion of the substrate includes:

[0016] Etching the third sacrificial layer to form a preset pattern;

[0017] The second sacrificial layer, the first sacrificial layer and the substrate are etched using the third sacrificial layer as a mask, and the third sacrificial layer is removed by etching during the etching of the second sacrificial layer, the first sacrificial layer and the substrate to form the boss and the active area.

[0018] In some possible embodiments, the material of the third sacrificial layer includes polysilicon, and the material of the substrate includes silicon.

[0019] In some possible embodiments, wet etching to remove the etching byproducts includes:

[0020] The etching byproducts are removed by wet etching, and the second layer, the first layer and the active area are tilted under the action of capillary force, and adjacent second layers are in contact and adhere to each other, and each first layer is spaced apart from each other, and each active area is spaced apart from each other.

[0021] In some possible embodiments, the material of the first sacrificial layer includes oxide, and the material of the second sacrificial layer includes nitride or oxynitride; or, the material of the first sacrificial layer includes oxygen-rich silicon-oxygen compound, and the material of the second sacrificial layer includes silicon-rich silicon-oxygen compound;

[0022] While removing the etching byproducts by wet etching, a portion of the sidewall of the first layer is also removed by etching, so that the sidewall of the first layer is recessed below the sidewall of the second layer.

[0023] In some possible embodiments, the wet etching solution includes a diluted hydrofluoric acid solution.

[0024] In some possible embodiments, removing the bosses, and releasing the tilted state of each active area and restoring the upright state, comprises:

[0025] Step a: using a reaction gas to react with the second layer and the first layer to form reactants on the surfaces of the first layer and the second layer;

[0026] Step b: heating the reactants to decompose and form a plurality of gas products;

[0027] Repeat step a and step b in sequence until the first layer and the second layer are both removed by reaction, and the active region is released from the tilted state and exposed.

[0028] In some possible embodiments, the material of the first layer includes silicon oxide, and the material of the second layer includes silicon nitride or silicon oxynitride; or, the material of the first sacrificial layer includes oxygen-rich silicon oxynitride, and the material of the second sacrificial layer includes silicon-rich silicon oxynitride;

[0029] The reaction gas includes ammonia gas and hydrofluoric acid gas, and the reactants are heated to 100° C.-200° C.

[0030] In some possible embodiments, the material of the first sacrificial layer includes carbon, and the material of the second sacrificial layer includes nitride or nitride oxide;

[0031] Before wet etching to remove the etching byproducts, the method further includes: using a first etching gas to dry etch and remove a portion of the sidewall of the first layer, so that the sidewall of the first layer is recessed below the sidewall of the second layer, and etching to remove a portion of the byproducts.

[0032] In some possible embodiments, removing the bosses, and releasing the tilted state of each active area and restoring the upright state, comprises:

[0033] Step a: using a reaction gas to react with the second layer to form a reactant on the surface of the second layer;

[0034] Step b: heating the reactants to decompose and form a plurality of gas products;

[0035] Repeating the step a and the step b in sequence until the second layer is removed by reaction, the first layer is exposed, and the active region is released from the tilted state;

[0036] The first layer is removed by dry etching using a second etching gas, thereby exposing the active area.

[0037] In some possible embodiments, the first etching gas includes hydrogen and nitrogen, and the second etching gas includes hydrogen or helium.

[0038] In some possible embodiments, the material of the second layer includes silicon nitride or silicon oxynitride, the reaction gas includes ammonia gas and hydrofluoric acid gas, and the reactants are heated to 100° C.-200° C.

[0039] In some possible embodiments, the orthographic projection of the second layer on the substrate covers the orthographic projection of the first layer on the substrate, and the distance between the edge of the orthographic projection of the second layer on the substrate and the edge of the orthographic projection of the first layer on the substrate is less than 1.5 nm.

[0040] The method for manufacturing a semiconductor structure provided by the embodiment of the present disclosure has at least the following advantages:

[0041] In the method for manufacturing a semiconductor structure provided by an embodiment of the present disclosure, a substrate and a sacrificial structure thereon are etched to form correspondingly connected active areas and bosses, as well as etching byproducts located between the active areas. The etching byproducts are removed by wet etching, and the adjacent bosses are in contact and adhered to the partial area away from the substrate, and the active areas are spaced apart, so that the adjacent active areas are not adhered together, and the inclined state is maintained by the adhesion of the bosses. By removing the bosses, the inclined state of each active area is released, and the upright state is restored, and the active area is prevented from tilting. At the same time, the active areas are spaced apart, and there is no need to oxidize the active areas to form an oxide layer to achieve isolation, which can ensure the critical dimensions of the active areas and avoid the loss of critical dimensions. It is also convenient for the diffusion of the reaction gas and the reaction between the bosses, so that the bosses can be completely removed, and the active areas are prevented from remaining in a tilted state due to the adhesion of the remaining bosses, and the tilt of the active areas is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A process diagram for forming an active region in the related art;

[0043] Figure 2 A schematic diagram of an active area tilt in the related art;

[0044] Figure 3 A schematic diagram of restoring the upright position of the active area in the related art;

[0045] Figure 4 A schematic diagram of a partial active area tilt in the related art;

[0046] Figure 5 for Figure 4 A partial enlarged view of the middle A;

[0047] Figure 6is a flow chart of a method for manufacturing a semiconductor structure in an embodiment of the present disclosure;

[0048] Figure 7 is a schematic diagram after forming a sacrificial structure in one embodiment of the present disclosure;

[0049] Figure 8 It is a schematic diagram after etching the third sacrificial layer in one embodiment of the present disclosure;

[0050] Fig. 9 It is a schematic diagram after forming a boss in one embodiment of the present disclosure;

[0051] Fig.10 It is a schematic diagram of bosses contacting and adhering to each other in one embodiment of the present disclosure;

[0052] Fig.11 A schematic diagram of restoring the upright state of the active region in one embodiment of the present disclosure;

[0053] Fig.12 A process diagram of removing the first layer and the second layer in one embodiment of the present disclosure;

[0054] Fig.13 It is a schematic diagram after etching the sidewall of the first layer in one embodiment of the present disclosure;

[0055] Fig.14 is a process diagram of removing the second layer in one embodiment of the present disclosure;

[0056] Fig.15 It is a schematic diagram after removing the second layer in one embodiment of the present disclosure.

[0057] Description of reference numerals:

[0058] 10-substrate; 11-active region;

[0059] 12- Etching byproducts; 13- Oxide layer;

[0060] 14-contact groove; 20-sacrificial structure;

[0061] 21-first sacrificial layer; 22-second sacrificial layer;

[0062] 23-third sacrificial layer; 30-boss;

[0063] 31-first layer; 32-second layer;

[0064] 33-isolation tank; 40-reactant. DETAILED DESCRIPTION

[0065] See also Figures 1 to 5In the related art, there is a problem that the active area 11 is prone to tilt. The inventor has found that the reason is that when the semiconductor structure is manufactured, Figure 1 Usually, active regions 11 are first formed by etching in the substrate 10, and etching byproducts 12 are formed between the active regions 11. Figure 2 , and then wet etching is performed to remove the etching byproducts 12. Due to the action of capillary force, the two adjacent active regions 11 are tilted toward each other, and the surfaces of the active regions 11 are covered with oxide layers 13, and the oxide layers 13 are in contact and adhere to each other. The active regions 11 are then oxidized to thicken the oxide layers 13, thereby preventing the active regions 11 from contacting each other. Figure 3 , and then dry-etching to remove the oxide layer 13, so that the active area 11 can be restored to its upright state.

[0066] In the above production process, refer to Figure 4 and Figure 5 , the etching gas is difficult to diffuse between the active areas 11, the oxide layer 13 between the active areas 11 is difficult to remove, the substances generated by the reaction are also difficult to volatilize, and the oxide layer 13 is difficult to completely remove, so that part of the active area 11 is still tilted. In addition, the oxide layer 13 is formed by oxidation of the active area 11 and is finally removed, resulting in a loss of the critical size of the active area 11.

[0067] The disclosed embodiment provides a method for manufacturing a semiconductor structure, in which bosses are formed correspondingly on the active area, and when wet etching is performed to remove etching byproducts, adjacent bosses are in contact and adhere to the partial area away from the substrate, and each active area is spaced apart. Adjacent active areas are not adhered together, but rely on the adhesion of the bosses to maintain an inclined state, which is convenient for the diffusion of the reaction gas and the reaction between the bosses, and is convenient for completely removing the bosses, avoiding the active area from remaining in an inclined state due to the adhesion of the remaining bosses, and avoiding the tilting of the active area. At the same time, there is no need to oxidize the active area to form an oxide layer to achieve isolation, which can ensure the critical size of the active area and avoid the loss of the critical size.

[0068] In order to make the above-mentioned purposes, features and advantages of the embodiments of the present disclosure more obvious and understandable, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

[0069] See also Figure 6 The present disclosure provides a method for manufacturing a semiconductor structure, the method comprising the following steps:

[0070] Step S100: forming a sacrificial structure on a substrate.

[0071] See also Figure 7 The substrate 10 provides support and is used to form the active area 11, and its material can be a semiconductor material, such as single crystal silicon, polycrystalline silicon, silicon on insulator (SOI), germanium, etc. The sacrificial structure 20 is formed on the substrate 10, and is used to etch a mask to form the active area 11, and is also used to form a corresponding boss 30 set on the substrate 10 to increase the overall height of the active area 11 and the corresponding boss 30. The sacrificial structure 20 can be a stacked structure to facilitate layered processing of the sacrificial structure 20.

[0072] In some examples, forming a sacrificial structure 20 on a substrate 10 includes: forming at least two sacrificial layers stacked in sequence on the substrate 10, and the at least two sacrificial layers form the sacrificial structure 20. Among them, a sacrificial layer is formed on the substrate 10, and another sacrificial layer is formed on the sacrificial layer until all the sacrificial layers are formed, and these sacrificial layers are stacked in sequence on the substrate 10 to form the sacrificial structure 20, that is, the sacrificial structure 20 includes two or more sacrificial layers stacked in sequence. The materials of at least two sacrificial layers can be different, or the materials of some sacrificial layers can be the same, so that the required sacrificial layers can be processed separately.

[0073] Step S200: etching the sacrificial structure and the substrate to form a plurality of active areas spaced apart from each other in the substrate, with etching byproducts between adjacent active areas, and forming a boss corresponding to each active area in the sacrificial structure.

[0074] See also Figures 7 to 9 , the sacrificial structure 20 and the substrate 10 are etched, and part of the sacrificial structure 20 and part of the substrate 10 are removed to form a plurality of active areas 11 spaced apart in the substrate 10. Contact grooves 14 surrounding each active area 11 are also formed in the substrate 10, and etching byproducts 12 are present between adjacent active areas 11, that is, etching byproducts 12, such as polymers, are present in the contact grooves 14.

[0075] The sacrificial structure 20 forms a plurality of spaced bosses 30, one boss 30 being correspondingly disposed on each active region 11, and the corresponding active regions 11 and bosses 30 are columnar. An isolation groove 33 surrounding each boss 30 is also formed in the sacrificial structure 20, and the isolation groove 33 penetrates the sacrificial structure 20. The isolation groove 33 is opposite to and connected to the contact groove 14, that is, the gap between each boss 30 is opposite to and connected to the gap between each active region 11.

[0076] Based on the example of forming at least two sacrificial layers stacked in sequence on a substrate 10, and at least two sacrificial layers forming a sacrificial structure 20, etching the sacrificial structure 20 and the substrate 10 includes: etching each sacrificial layer and the substrate 10 to form an active area 11 and a boss 30, wherein the boss 30 includes at least two layers, and the number of layers is less than or equal to the number of sacrificial layers, and each layer corresponds to a sacrificial layer.

[0077] Among them, at least two sacrificial layers are etched to form the boss 30, and the boss 30 has at least two layers, and the at least two layers are stacked in sequence, and each layer corresponds to a sacrificial layer, that is, each remaining sacrificial layer forms a layer of the boss 30. The number of layers is less than or equal to the number of sacrificial layers. When at least one sacrificial layer away from the substrate 10 is etched and removed in its entirety, the number of layers is less than the number of sacrificial layers. When at least two sacrificial layers are etched and removed partially, the number of layers is equal to the number of sacrificial layers.

[0078] Step S300: wet etching is performed to remove etching byproducts, and adjacent bosses are in contact and adhere to each other in a partial area away from the substrate, and active areas corresponding to the bosses are spaced apart and in an inclined state.

[0079] See also Figure 8 and Fig. 9 , wet etching is performed to remove the etching byproducts 12, and the etching solution may include a diluted hydrofluoric acid (HF) solution. At the same time, due to the capillary force of the liquid, each active area 11 and the corresponding boss 30 are tilted, and the tilt direction of the corresponding active area 11 and boss 30 ( Fig.10 The left and right directions shown are consistent.

[0080] The adjacent protrusions 30 are in contact and adhered to the partial areas away from the substrate 10, and the active areas 11 correspondingly connected to the protrusions 30 are spaced apart and in an inclined state. The active area 11 and the corresponding protrusions 30 are tilted as a whole under the action of capillary force. The tilt height is constant. When the tops of the adjacent protrusions 30 are adhered together, the active area 11 is in an inclined state and still has a certain distance from the top of the protrusion 30, so that there is still a gap between the adjacent active areas 11, that is, the adjacent active areas 11 are spaced apart.

[0081] Such a configuration, on the one hand, avoids contact between active areas 11, and does not require oxidation treatment of active areas 11 to form an oxide layer in part of active areas 11 to achieve isolation, which can ensure the critical dimension (CD) of active areas 11 and avoid loss of critical dimensions. On the other hand, the boss 30 is located above the active area 11, which is convenient for diffusion of reaction gas and reaction with the boss 30, and is convenient for removal of the boss 30, so that the active area 11 is released from the tilted state, and the active area 11 is prevented from remaining tilted due to adhesion of the remaining boss 30, thereby reducing the tilt of the active area 11.

[0082] Step S400: removing the bosses, and releasing the tilted state of each active area and restoring the upright state.

[0083] See also Fig.10 and Fig.11 , the bosses 30 are removed to expose the top surfaces of the active regions 11. The active regions 11 are not adhered to each other, and rely on the adhesion of the bosses 30 to maintain the tilted state. When the bosses 30 are removed, the active regions 11 are released from the tilted state and restored to stand upright, thereby avoiding the active regions 11 from tilting. In the process of removing the etching byproducts 12 and removing the bosses 30, the active regions 11 will not be consumed, thereby avoiding the loss of the critical dimensions of the active regions 11.

[0084] In summary, in the method for manufacturing a semiconductor structure provided by the embodiment of the present disclosure, the substrate 10 and the sacrificial structure 20 thereon are etched to form correspondingly connected active areas 11 and bosses 30, as well as etching byproducts 12 located between the active areas 11. The etching byproducts 12 are removed by wet etching, and the adjacent bosses 30 are in contact and adhered to the partial area away from the substrate 10, and the active areas 11 are spaced apart, so that the adjacent active areas 11 are not adhered together, and the inclined state is maintained by the adhesion of the bosses 30. By removing the bosses 30, the inclined state of each active area 11 is released and restored to an upright state, thereby avoiding the active area 11 from tilting. At the same time, the active areas 11 are spaced apart, and there is no need to oxidize the active areas 11 to form an oxide layer to achieve isolation, which can ensure the critical size of the active area 11 and avoid the loss of the critical size. It also facilitates the diffusion of the reaction gas and the reaction with the boss 30 , and facilitates the complete removal of the boss 30 , thereby preventing the active area 11 from remaining in a tilted state due to the adhesion of the remaining boss 30 , thereby preventing the active area 11 from tilting.

[0085] For some possible examples, see Figure 7, forming a sacrificial structure 20 on a substrate 10, including: forming a first sacrificial layer 21 on the substrate 10, forming a second sacrificial layer 22 on the first sacrificial layer 21, and forming a third sacrificial layer 23 on the second sacrificial layer 22, wherein the third sacrificial layer 23, the second sacrificial layer 22 and the first sacrificial layer 21 form the sacrificial structure 20. That is, in a direction away from the substrate 10, the sacrificial structure 20 includes the first sacrificial layer 21, the second sacrificial layer 22 and the third sacrificial layer 23 which are sequentially stacked, and the first sacrificial layer 21, the second sacrificial layer 22 and the third sacrificial layer 23 can all be formed by a deposition process.

[0086] Accordingly, see Figure 8 , etching the sacrificial structure 20 and the substrate 10, including: etching and removing the third sacrificial layer 23, part of the second sacrificial layer 22, part of the first sacrificial layer 21 and part of the substrate 10, to form an active area 11 and a boss 30, wherein the boss 30 includes a first layer 31 and a second layer 32, the first layer 31 includes the remaining first sacrificial layer 21, and the second layer 32 includes the remaining second sacrificial layer 22.

[0087] See also Figures 7 to 9 When etching the third sacrificial layer 23, the second sacrificial layer 22, the first sacrificial layer 21 and the substrate 10, all of the third sacrificial layer 23, part of the second sacrificial layer 22, part of the first sacrificial layer 21 and part of the substrate 10 are removed, that is, the third sacrificial layer 23 is completely consumed and removed during the etching process, and an active area 11 is formed in the remaining substrate 10, and the remaining first sacrificial layer 21 and the remaining second sacrificial layer 22 form a boss 30.

[0088] The boss 30 includes a first layer 31 disposed on the active area 11, and a second layer 32 disposed on the first layer 31. The first layer 31 corresponds to the remaining first sacrificial layer 21, and the second layer 32 corresponds to the remaining second sacrificial layer 22, that is, the remaining first sacrificial layer 21 forms the first layer 31, and the remaining second sacrificial layer 22 forms the second layer 32. In the process of etching the third sacrificial layer 23, the second sacrificial layer 22, the first sacrificial layer 21 and the substrate 10, etching byproducts 12 are formed, and most of the etching byproducts 12 are formed by etching the substrate 10, and are located between the active areas 11, for example, attached to the surface of the active area 11.

[0089] In some possible implementations, such as Figure 7 and Figure 8 As shown, etching and removing the third sacrificial layer 23, part of the second sacrificial layer 22, part of the first sacrificial layer 21 and part of the substrate 10 includes: etching the third sacrificial layer 23 to form a preset pattern; using the third sacrificial layer 23 as a mask, etching the second sacrificial layer 22, the first sacrificial layer 21 and the substrate 10, and etching and removing the third sacrificial layer 23 during the etching of the second sacrificial layer 22, the first sacrificial layer 21 and the substrate 10 to form a boss 30 and an active area 11.

[0090] Among them, Figure 8 As shown, the third sacrificial layer 23 is etched, a portion of the third sacrificial layer 23 is removed, a preset pattern is formed on the third sacrificial layer 23, and a portion of the surface of the second sacrificial layer 22 is exposed. The second sacrificial layer 22, the first sacrificial layer 21, and the substrate 10 are etched using the remaining third sacrificial layer 23 as a mask, and the preset pattern of the third sacrificial layer 23 is transferred to the second sacrificial layer 22, the first sacrificial layer 21, and the substrate 10. In addition, in the process of etching the second sacrificial layer 22, the first sacrificial layer 21, and the substrate 10, the remaining third sacrificial layer 23 is etched away at the same time, that is, all of the third sacrificial layer 23 is removed, and a portion of the second sacrificial layer 22 and a portion of the first sacrificial layer 21 are retained to form a second layer 32 and a first layer 31, respectively.

[0091] Exemplarily, the material of the third sacrificial layer 23 includes polysilicon, and the material of the substrate 10 includes silicon, that is, the material of the third sacrificial layer 23 is homogeneous with the material of the substrate 10, and the remaining third sacrificial layer 23 is etched away while the substrate 10 is etched away. The third sacrificial layer 23 is used as a mask and does not need to be removed separately. The thickness of the third sacrificial layer 23, the second sacrificial layer 22, and the first sacrificial layer 21 can be determined according to the specific process.

[0092] In some other possible examples, forming the sacrificial structure 20 on the substrate 10 includes: forming a first sacrificial layer 21 on the substrate 10 , forming a second sacrificial layer 22 on the first sacrificial layer 21 , and the second sacrificial layer 22 and the first sacrificial layer 21 form the sacrificial structure 20 .

[0093] Correspondingly, etching the sacrificial structure 20 and the substrate 10 includes: etching and removing part of the second sacrificial layer 22, part of the first sacrificial layer 21 and part of the substrate 10 to form an active area 11 and a boss 30, wherein the boss 30 includes a first layer 31 and a second layer 32, the first layer 31 includes the remaining first sacrificial layer 21, and the second layer 32 includes the remaining second sacrificial layer 22.

[0094] See also Fig. 9 and Fig.10 In the example where the boss 30 includes a first layer 31 and a second layer 32, wet etching to remove the etching byproducts 12 includes: wet etching to remove the etching byproducts 12, the second layer 32, the first layer 31 and the active area 11 are tilted under the action of capillary force, adjacent second layers 32 are in contact and adhere to each other, each first layer 31 is spaced apart, and each active area 11 is spaced apart.

[0095] Wet etching removes the etching byproducts 12 to clean the active area 11 and the boss 30. Under the action of capillary force, the adjacent second layers 32 are in contact and adhere to each other, the adjacent first layers 31 are spaced apart, and the adjacent active areas 11 are spaced apart. When the heights of the active area 11, the first layers 31, and the second layers 32 are constant, the second layers 32 are adhered to each other, and the first layers 31 are separated, which increases the distance between the active areas 11 and ensures that the active areas 11 do not adhere to each other.

[0096] In order to prevent adjacent first layers 31 from contacting and adhering to each other, in some examples, while or before wet etching to remove the etching byproducts 12, part of the sidewall of the first layer 31 may be etched away, so that the sidewall of the first layer 31 is recessed in the sidewall of the second layer 32, so that the critical dimension between adjacent first layers 31 is greater than the critical dimension between adjacent second layers 32, that is, the distance between adjacent first layers 31 is greater than the distance between adjacent second layers 32. In this way, when adjacent second layers 32 contact and adhere to each other, the first layer 31 is connected to the bottom of the second layer 32, and the distance between adjacent first layers 31 is greater, so that adjacent first layers 31 are not easy to contact each other.

[0097] In some possible implementations, such as Fig. 9 and Fig.10 As shown, the material of the first sacrificial layer 21 includes oxide, and the material of the second sacrificial layer 22 includes nitride or oxynitride; or, the material of the first sacrificial layer 21 includes oxygen-rich silicon-oxygen compound, and the material of the second sacrificial layer 22 includes silicon-rich silicon-oxygen compound; accordingly, while wet etching removes the etching by-products 12, part of the side wall of the first layer 31 is also etched away, so that the side wall of the first layer 31 is recessed in the side wall of the second layer 32.

[0098] For example, the material of the first sacrificial layer 21 may be silicon oxide, and the material of the second sacrificial layer 22 may be silicon nitride or silicon oxynitride. Alternatively, the material of the first sacrificial layer 21 may be oxygen-rich SiO x N y ), the material of the second sacrificial layer 22 can be silicon-rich SiO x N y ). Among them, oxygen-rich silicon oxynitride means that the atomic ratio of silicon to oxygen in the silicon oxynitride is less than 1, and silicon-rich silicon oxynitride means that the atomic ratio of silicon to oxygen in the silicon oxynitride is greater than 1.

[0099] With such a configuration, the second sacrificial layer 22 has a higher hardness, can improve the selectivity of etching, and has a more uniform etching effect. At the same time, the first sacrificial layer 21 is easier to etch, and can be etched away together with the etching byproduct 12. The critical dimension of the first layer 31 formed by the remaining first sacrificial layer 21 is larger, so that the sidewall of the first layer 31 is recessed in the sidewall of the second layer 32. For example, the wet etching etchant includes a diluted hydrofluoric acid solution to etch away the etching byproduct 12 and etch the sidewall of the first layer 31, so that the first layer 31 is circumferentially smaller.

[0100] The orthographic projection of the second layer 32 on the substrate 10 covers the orthographic projection of the first layer 31 on the substrate 10, and the distance between the edge of the orthographic projection of the second layer 32 on the substrate 10 and the edge of the orthographic projection of the first layer 31 on the substrate 10 is less than 1.5 nm, so as to avoid the first layer 31 being too small and easy to collapse and difficult to support the second layer 32. The orthographic projection of the first layer 31 on the substrate 10 is located in the active area 11, and the distance between the edge of the orthographic projection of the first layer 31 on the substrate 10 and the edge of the active area 11 can also be less than 1.5 nm.

[0101] See also Fig.12 On the basis that the material of the first sacrificial layer 21 includes oxide, and the material of the second sacrificial layer 22 includes nitride or oxynitride; or, the material of the first sacrificial layer 21 includes oxygen-rich silicon-oxygen compound, and the material of the second sacrificial layer 22 includes silicon-rich silicon-oxygen compound, the boss 30 is removed, and each active area 11 is released from the tilted state and restored to an upright state, including:

[0102] Step a: using a reaction gas to react with the second layer 32 and the first layer 31 to form a reactant 40 on the surfaces of the first layer 31 and the second layer 32;

[0103] Step b: heating the reactant 40, and decomposing the reactant 40 to form a plurality of gas products;

[0104] Step a and step b are repeated in sequence until the first layer 31 and the second layer 32 are both removed by reaction, and the active region 11 is released from the tilted state and exposed.

[0105] The first layer 31 is formed by the first sacrificial layer 21, and the second layer 32 is formed by the second sacrificial layer 22. The material of the first layer 31 includes oxide, and the material of the second layer 32 includes nitride or oxynitride; or, the material of the first layer 31 includes oxygen-rich silicon oxide, and the material of the second layer 32 includes silicon-rich silicon oxide.

[0106] The first layer 31 and the second layer 32 can be etched by cyclic evaporation, that is, the first layer 31 and the second layer 32 are divided into multiple parts and removed by multiple reactions. Fig.12As shown, the reaction gas reacts with the first layer 31 and the second layer 32 to form a reactant 40, and the reactant 40 is located on the surface of the first layer 31 and the second layer 32. The reactant 40 is then heated to cause a decomposition reaction in the reactant 40 to form a plurality of gas products, thereby exposing the remaining first layer 31 and the second layer 32, and the process of generating the reactant 40 and decomposing the reactant 40 is repeated until all the first layers 31 and the second layers 32 are completely removed.

[0107] The first temperature when the reaction gas reacts with the second layer 32 and the first layer 31 to form the reactant 40 is lower than the second temperature when the reactant 40 undergoes a decomposition reaction, and the semiconductor structure is in a cycle of the first temperature-the second temperature until the first layer 31 and the second layer 32 are both removed by the reaction. The reaction of the reaction gas with the second layer 32 and the reaction of the reaction gas with the first layer 31 are not chemical reactions, and except for the reactant 40, all other products are gases.

[0108] In some examples, the material of the first layer 31 includes silicon oxide, and the material of the second layer 32 includes silicon nitride or silicon oxynitride; or, the material of the first sacrificial layer 21 includes oxygen-rich silicon oxynitride, and the material of the second sacrificial layer 22 includes silicon-rich silicon oxynitride; the reaction gas includes ammonia and hydrofluoric acid gas, and the reactants are heated from 40 to 100° C. to 200° C. Silicon oxide, ammonia and hydrofluoric acid gas react to form ammonium fluorosilicate and oxygen, silicon nitride, ammonia and hydrofluoric acid gas react to form ammonium fluorosilicate and nitrogen, and the chemical formula of ammonium fluorosilicate is (NH4)2SiF6. Ammonium fluorosilicate decomposes under heat to form hydrogen, hydrofluoric acid gas and silicon tetrafluoride gas.

[0109] In some other possible implementations, the material of the first sacrificial layer 21 includes carbon, and the material of the second sacrificial layer 22 includes nitride or nitride oxide, see Fig.13 Before wet etching to remove the etching byproducts 12 , the method further includes: using the first etching gas to dry etch and remove part of the sidewall of the first layer 31 , so that the sidewall of the first layer 31 is recessed into the sidewall of the second layer 32 , and etching and removing part of the etching byproducts 12 .

[0110] The first etching gas is used to etch the sidewall of the first layer 31, so that the first layer 31 is circumferentially reduced, and the sidewall of the first layer 31 is recessed in the sidewall of the second layer 32. The first etching gas includes hydrogen and nitrogen, and the first etching gas will also etch and remove part of the etching byproducts 12. The first etching gas has a greater selectivity for the first layer 31 than for the etching byproducts 12, and the etching byproducts 12 also need to be cleaned and removed. In the process of etching the first layer 31 and the etching byproducts 12, dry etching is used, there is no liquid, and no tilting occurs, and the second layer 32, the first layer 31 and the active area 11 are all kept upright.

[0111] The orthographic projection of the second layer 32 on the substrate 10 covers the orthographic projection of the first layer 31 on the substrate 10, and the distance between the edge of the orthographic projection of the second layer 32 on the substrate 10 and the edge of the orthographic projection of the first layer 31 on the substrate 10 is less than 1.5 nm, so as to avoid the first layer 31 being too small and easy to collapse and difficult to support the second layer 32. The orthographic projection of the first layer 31 on the substrate 10 is located in the active area 11, and the distance between the edge of the orthographic projection of the first layer 31 on the substrate 10 and the edge of the active area 11 can also be less than 1.5 nm.

[0112] See also Fig.14 and Fig.15 Based on the example in which the material of the first sacrificial layer 21 includes carbon and the material of the second sacrificial layer 22 includes nitride or oxynitride, the boss 30 is removed, and each active area 11 is released from the tilted state and exposed, including:

[0113] Step a: using a reaction gas to react with the second layer 32 to form a reactant 40 on the surface of the second layer 32 .

[0114] Step b: heating the reactant 40, and the reactant 40 decomposes to form a plurality of gas products.

[0115] Step a and step b are repeated in sequence until the second layer 32 is removed by reaction, the first layer 31 is exposed, and the active region 11 is released from the tilted state.

[0116] The first layer 31 is removed by dry etching using a second etching gas, and the active area 11 is exposed.

[0117] The first layer 31 is formed by the first sacrificial layer 21, and the second layer 32 is formed by the second sacrificial layer 22. The material of the first layer 31 includes carbon, and the material of the second layer 32 includes nitride or oxynitride. The second layer 32 can be removed by cyclic evaporation etching, and the first layer 31 can be removed by dry etching, such as ashing.

[0118] like Fig.14 As shown, the reaction gas reacts with the second layer 32 to form a reactant 40, and the reactant 40 is located on the surface of the second layer 32. The reactant 40 is then heated to cause a decomposition reaction in the reactant 40 to form a plurality of gas products, thereby exposing the remaining second layer 32. The process of generating the reactant 40 and decomposing the reactant 40 is repeated until all the second layers 32 are completely removed and the first layer 31 is exposed.

[0119] The first temperature when the reaction gas reacts with the second layer 32 to form the reactant 40 is lower than the second temperature when the reactant 40 undergoes a decomposition reaction, and the semiconductor structure is in a cycle of the first temperature-the second temperature until the first layer 31 is removed by the reaction. The reaction of the reaction gas with the second layer 32 is not a chemical reaction, and except for the reactant 40, all other products are gases.

[0120] Since the second layer 32 is in contact and adheres, when the second layer 32 is removed by reaction, the active region 11 is freed from the tilted state and restored to an upright state. Fig.15 As shown, the active region 11 is also connected to a first layer 31, which is then removed by dry etching to expose the active region 11. The second etching gas includes hydrogen or helium, which can avoid loss of critical dimensions of the active region 11 while removing the first layer 31.

[0121] Exemplarily, the material of the second layer 32 includes silicon nitride or silicon oxynitride, the reaction gas includes ammonia and hydrofluoric acid gas, and the reactants are heated to 40 to 100° C.-200° C. Silicon oxide, ammonia and hydrofluoric acid gas react to form ammonium fluorosilicate and oxygen, silicon nitride, ammonia and hydrofluoric acid gas react to form ammonium fluorosilicate and nitrogen, and the chemical formula of ammonium fluorosilicate is (NH4)2SiF6. Ammonium fluorosilicate decomposes under heat to form hydrogen, hydrofluoric acid gas and silicon tetrafluoride gas.

[0122] In this specification, each embodiment or implementation is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referenced to each other. The description of reference terms such as "one implementation", "some implementations", "illustrative implementations", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the implementation or example are included in at least one implementation or example of the present disclosure. In this specification, the schematic representation of the above terms does not necessarily refer to the same implementation or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more implementations or examples in a suitable manner.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A method for manufacturing a semiconductor structure, characterized in that: include: forming a sacrificial structure on the substrate; Etching the sacrificial structure and the substrate, forming a plurality of active areas spaced apart from each other in the substrate, with etching byproducts between adjacent active areas, and forming a boss corresponding to each active area on the sacrificial structure; Wet etching is performed to remove the etching byproducts, so that the adjacent bosses are in contact and adhere to each other at partial regions away from the substrate, and the active regions corresponding to the bosses are spaced apart and in an inclined state; By removing the bosses, each active area is freed from the tilted state and restored to an upright state.

2. The method according to claim 1, characterized in that: Forming the sacrificial structure on the substrate comprises: forming at least two sacrificial layers stacked in sequence on the substrate, wherein the at least two sacrificial layers form the sacrificial structure; Etching the sacrificial structure and the substrate includes: etching each of the sacrificial layers and the substrate to form the active area and the boss, wherein the boss includes at least two layers, and the number of the layers is less than or equal to the number of the sacrificial layers, and each of the layers corresponds to one sacrificial layer.

3. The method according to claim 2, characterized in that: Forming the sacrificial structure on the substrate comprises: forming a first sacrificial layer on the substrate, forming a second sacrificial layer on the first sacrificial layer, and forming a third sacrificial layer on the second sacrificial layer, wherein the third sacrificial layer, the second sacrificial layer and the first sacrificial layer form the sacrificial structure; Etching the sacrificial structure and the substrate, comprising: The third sacrificial layer, part of the second sacrificial layer, part of the first sacrificial layer and part of the substrate are etched away to form the active area and the boss, wherein the boss includes a first layer and a second layer, the first layer includes the remaining first sacrificial layer, and the second layer includes the remaining second sacrificial layer.

4. The method according to claim 3, characterized in that: Etching and removing the third sacrificial layer, a portion of the second sacrificial layer, a portion of the first sacrificial layer, and a portion of the substrate, comprises: Etching the third sacrificial layer to form a preset pattern; The second sacrificial layer, the first sacrificial layer and the substrate are etched using the third sacrificial layer as a mask, and the third sacrificial layer is removed by etching during the etching of the second sacrificial layer, the first sacrificial layer and the substrate to form the boss and the active area.

5. The method according to claim 4, characterized in that: The material of the third sacrificial layer includes polysilicon, and the material of the substrate includes silicon.

6. The method according to claim 3, characterized in that: Wet etching to remove the etching byproducts includes: The etching byproducts are removed by wet etching, and the second layer, the first layer and the active area are tilted under the action of capillary force, adjacent second layers are in contact and adhere to each other, each first layer is spaced apart, and each active area is spaced apart.

7. The manufacturing method according to claim 6, characterized in that: The material of the first sacrificial layer includes oxide, and the material of the second sacrificial layer includes nitride or oxynitride; or, the material of the first sacrificial layer includes oxygen-rich silicon-oxygen compound, and the material of the second sacrificial layer includes silicon-rich silicon-oxygen compound; While removing the etching byproducts by wet etching, a portion of the sidewall of the first layer is also removed by etching, so that the sidewall of the first layer is recessed below the sidewall of the second layer.

8. The method according to claim 7, characterized in that: The wet etching solution includes a diluted hydrofluoric acid solution.

9. The production method according to claim 6 or 7, characterized in that: The bosses are removed, and each active area is freed from the tilted state and restored to an upright state, comprising: Step a: using a reaction gas to react with the second layer and the first layer to form reactants on the surfaces of the first layer and the second layer; Step b: heating the reactants to decompose and form a plurality of gas products; Repeat step a and step b in sequence until the first layer and the second layer are both removed by reaction, and the active region is released from the tilted state and exposed.

10. The manufacturing method according to claim 9, characterized in that: The material of the first layer includes silicon oxide, and the material of the second layer includes silicon nitride or silicon oxynitride; or, the material of the first sacrificial layer includes oxygen-rich silicon oxynitride, and the material of the second sacrificial layer includes silicon-rich silicon oxynitride; The reaction gas includes ammonia gas and hydrofluoric acid gas, and the reactants are heated to 100° C.-200° C.

11. The manufacturing method according to claim 6, characterized in that: The material of the first sacrificial layer includes carbon, and the material of the second sacrificial layer includes nitride or nitride oxide; Before wet etching to remove the etching byproducts, the method further includes: using a first etching gas to dry etch and remove a portion of the sidewall of the first layer, so that the sidewall of the first layer is recessed below the sidewall of the second layer, and etching to remove a portion of the byproducts.

12. The manufacturing method according to claim 11, characterized in that: The bosses are removed, and each active area is freed from the tilted state and restored to an upright state, comprising: Step a: using a reaction gas to react with the second layer to form a reactant on the surface of the second layer; Step b: heating the reactants to decompose and form a plurality of gas products; Repeating the step a and the step b in sequence until the second layer is removed by reaction, the first layer is exposed, and the active region is released from the tilted state; The first layer is removed by dry etching using a second etching gas, thereby exposing the active area.

13. The manufacturing method according to claim 12, characterized in that: The first etching gas includes hydrogen and nitrogen, and the second etching gas includes hydrogen or helium.

14. The production method according to claim 12 or 13, characterized in that: The material of the second layer includes silicon nitride or silicon oxynitride, the reaction gas includes ammonia gas and hydrofluoric acid gas, and the reactants are heated to 100° C.-200° C.

15. The production method according to claim 7 or 11, characterized in that: The orthographic projection of the second layer on the substrate covers the orthographic projection of the first layer on the substrate, and a distance between an edge of the orthographic projection of the second layer on the substrate and an edge of the orthographic projection of the first layer on the substrate is less than 1.5 nm.

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