Semiconductor structure and method of forming the same

Abstract

The present disclosure provides a semiconductor structure and a forming method thereof, and relates to the technical field of semiconductor. The forming method comprises the following steps: providing a substrate; forming an isolation groove in the substrate; introducing a seed gas comprising silicon ions into the isolation groove, the seed gas adhering to the inner wall of the isolation groove to form a seed layer; introducing a silicon-containing gas into the seed layer, the silicon-containing gas decomposing into solid matter and a first gas, the solid matter comprising silicon ions, the solid matter covering the surface formed by the seed layer and the inner wall of the isolation groove to form a target thin film. The target thin film formed by the method can increase the surface area of the active region of the substrate for forming a device, and prevent device manufacturing defects caused by insufficient depth of the isolation groove, thereby improving the yield of the device.

Description

Technical Field

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

[0002] Dynamic random access memory (DRAM) is widely used in smart devices such as mobile phones and tablets due to its small size, fast transmission speed, and high integration. As the size of terminal devices continues to decrease, the size of the memory is also shrinking, resulting in some structural defects in the memory.

[0003] Currently, due to the limitation of device size, the surface area of ​​the active region of the wafer used to prepare the device is also reduced, resulting in a low yield of the device.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the Invention

[0005] In view of this, the present disclosure provides a semiconductor structure and a method for forming the same, which can increase the surface area of ​​the substrate used to form the active region, prevent device manufacturing defects caused by insufficient isolation trench depth, and improve the device yield.

[0006] Other features and advantages of the present disclosure will become apparent from the following detailed description, or may be learned in part by practice of the present disclosure.

[0007] According to one aspect of the present disclosure, a method for forming a semiconductor structure is provided, the method comprising:

[0008] providing a substrate;

[0009] forming an isolation trench in the substrate;

[0010] introducing a seed gas into the isolation trench, wherein the seed gas includes silicon ions, and the seed gas adheres to an inner wall of the isolation trench to form a seed layer;

[0011] A silicon-containing gas is introduced into the seed layer, and the silicon-containing gas decomposes into a solid substance and a first gas. The solid substance includes silicon ions and covers the surface formed by the seed layer and the inner wall of the isolation groove to form a target film.

[0012] In some embodiments of the present disclosure, based on the aforementioned solution, the seed gas is dichlorosilane gas, and the solid matter is silicon atomic particles.

[0013] In some embodiments of the present disclosure, based on the aforementioned solution, the thickness of the target film increases gradually in a direction away from the substrate.

[0014] In some embodiments of the present disclosure, based on the above solution, before the silicon-containing gas is decomposed into the solid matter and the first gas, the process includes:

[0015] Under reaction conditions of a temperature of 300° C. to 500° C. and a pressure of 0.5 torr to 3 torr, the silicon-containing gas decomposes into a second gas and a third gas, and both the second gas and the third gas include silicon ions.

[0016] In some embodiments of the present disclosure, based on the aforementioned solution, the silicon-containing gas includes disilane, the first gas includes hydrogen, the second gas includes monosilane, and the third gas includes silene.

[0017] In some embodiments of the present disclosure, based on the above solution, after the silicon-containing gas is decomposed into the second gas and the third gas, the process includes:

[0018] Under reaction conditions of a temperature of 300° C. to 500° C. and a pressure of 0.5 torr to 3 torr, the second gas is decomposed into the third gas and the first gas.

[0019] In some embodiments of the present disclosure, based on the above solution, after the second gas is decomposed into the third gas and the first gas, the process includes:

[0020] Under reaction conditions of a temperature of 300° C. to 500° C. and a pressure of 0.5 torr to 3 torr, the third gas decomposes into the solid matter and the first gas.

[0021] In some embodiments of the present disclosure, based on the above solution, after the silicon-containing gas is decomposed into the second gas and the third gas, the process includes:

[0022] Under reaction conditions of a temperature of 520° C. to 750° C. and a pressure of 0.5 torr to 3 torr, the second gas decomposes into the solid matter and the first gas.

[0023] In some embodiments of the present disclosure, based on the above solution, vacuuming the isolation trench after forming the target thin film includes:

[0024] introducing the first gas into the target film;

[0025] Under reaction conditions of a temperature of 300° C. to 500° C. and a pressure of 1.5 torr to 3 torr, the third gas and the first gas are reacted to generate the second gas, and / or the second gas and the third gas are reacted to generate the first gas;

[0026] The isolation groove is evacuated to allow the generated second gas and / or the generated third gas to be discharged from the isolation groove.

[0027] According to another aspect of the present disclosure, a semiconductor structure is provided, comprising:

[0028] substrate;

[0029] an isolation trench located in the substrate;

[0030] a target film, the target film being located on an inner sidewall of the isolation trench, the target film comprising silicon ions;

[0031] The thickness of the target film increases gradually in a direction away from the substrate.

[0032] In one aspect, the present disclosure provides a method for forming a semiconductor structure. The method forms a seed layer on the inner wall of an isolation trench, introduces a silicon-containing gas into the seed layer, and decomposes the silicon-containing gas into a silicon-containing solid substance and a first gas. The solid substance covers the surface formed by the seed layer and the inner wall of the isolation trench, thereby forming a target thin film. This increases the surface area of ​​the side of the substrate where the isolation trench is formed, provides a larger active area for subsequent device formation, prevents manufacturing defects of subsequent devices caused by insufficient depth of the isolation trench, and improves the device yield.

[0033] On one hand, the present disclosure provides a semiconductor structure in which a target thin film is formed on the inner wall of an isolation trench. The semiconductor structure has a larger active area, which can improve the manufacturing quality of subsequent devices and increase the yield of the devices.

[0034] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification, are used to explain the principles of the present disclosure. Obviously, the drawings described below are only some embodiments of the present disclosure, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0036] Figure 1 FIG. 1 is a cross-sectional view of a substrate in a related art according to an exemplary embodiment of the present disclosure.

[0037] Figure 2 FIG. 1 is a top view of a substrate in a related art according to an exemplary embodiment of the present disclosure.

[0038] Figure 3The present invention is a flowchart of a method for forming a semiconductor structure according to an exemplary embodiment of the present disclosure.

[0039] Figure 4 It is a schematic structural diagram of a substrate with an isolation trench formed therein in an exemplary embodiment of the present disclosure.

[0040] Figure 5 Schematic diagram of the structure of a substrate for forming a seed layer in an exemplary embodiment of the present disclosure.

[0041] Figure 6 Schematic diagram of a semiconductor structure in an exemplary embodiment of the present disclosure.

[0042] Figure 7 Schematic diagram of the relationship between gas pressure and time in an exemplary embodiment of the present disclosure.

[0043] The description of the accompanying drawings is as follows:

[0044] 100: substrate; 200: oxide film layer; 300: isolation trench; 400: seed layer; 500: target film. DETAILED DESCRIPTION

[0045] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. Like reference numerals in the figures represent identical or similar structures, and thus their detailed descriptions will be omitted. Furthermore, the figures are merely schematic illustrations of the present disclosure and are not necessarily drawn to scale.

[0046] Although relative terms such as "upper" and "lower" are used in this specification to describe the relationship of one illustrated component to another, these terms are used herein for convenience only, such as in accordance with the orientation of the illustrations in the accompanying drawings. It will be understood that if the illustrated device were flipped upside down, the component described as "upper" would become the component "lower." When a structure is referred to as "on" another structure, this may mean that the structure is integrally formed with the other structure, that the structure is "directly" disposed on the other structure, or that the structure is "indirectly" disposed on the other structure via the other structure.

[0047] The terms "a", "an", "the", "said" and "at least one" are used to indicate the presence of one or more elements / components / etc.; the terms "including" and "having" are used to express open-ended inclusion and mean that additional elements / components / etc. may be present in addition to the listed elements / components / etc.; the terms "first", "second" and "third" etc. are used only as labels and are not intended to limit the quantity of their objects.

[0048] As the requirements for the size of Dynamic Random Access Memory (DRAM) become increasingly higher, especially when the overall size of the device structure is reduced, the effective area of ​​the active area of ​​the device is also reduced, resulting in the storage units in the active area being prone to poor contact or short circuits. Among them, the area on the substrate used to form device structures such as transistors and capacitors is the active area. The active areas on the same substrate are usually separated by isolation grooves or isolation structures to form different devices in different active areas. In related technologies, isolation grooves are usually etched on the substrate first, but due to the limitations of the preparation process, the isolation grooves are usually "V"-shaped or "V"-like structures in the direction perpendicular to the substrate, such as Figure 1 and Figure 2 As shown, the bottom opening width of the isolation trench 300 is smaller than the top opening width, resulting in a smaller surface area on the side of the substrate 100 where the top opening of the isolation trench 300 is located. Furthermore, subsequent processing forms an oxide film 200 within the isolation trench 300 through an in-situ steam generation (ISSG) reaction. The ISSG reaction further consumes the area of ​​the active region. During subsequent device fabrication, this isolation trench 300 structure not only results in device feature dimensions failing to meet fabrication requirements, but also affects device fabrication quality and may even cause short circuits between devices.

[0049] Based on this, the present disclosure provides a method for forming a semiconductor structure, such as Figure 3 As shown, the forming method includes steps S101 to S104, wherein:

[0050] Step S101: providing a substrate;

[0051] Step S102: forming an isolation trench in the substrate;

[0052] Step S103: introducing a seed gas into the isolation trench, the seed gas including silicon ions, and the seed gas adhering to the inner wall of the isolation trench to form a seed layer;

[0053] Step S104: introducing silicon-containing gas into the seed layer, the silicon-containing gas decomposes into solid matter and a first gas, the solid matter including silicon ions, and the solid matter covers the surface formed by the seed layer and the inner wall of the isolation groove to form a target film.

[0054] The present disclosure provides a method for forming a semiconductor structure, which forms an isolation trench on a substrate, introduces a seed gas into the isolation trench, forms a seed layer on the inner wall of the isolation trench, and introduces a silicon-containing gas into the seed layer to decompose the silicon-containing gas into a silicon-containing solid substance and a first gas. The solid substance covers the surface formed by the seed layer and the inner wall of the isolation trench to form a target film. The target film has the same silicon ions as the substrate. The target film is formed on the inner wall of the isolation trench to increase the surface area of ​​the top of the isolation trench. The seed layer is mainly attached to the top of the isolation trench. The seed layer allows more solid substances to attach to the top of the isolation trench, thereby forming the target film in one step, that is, increasing the effective area of ​​the active area of ​​the substrate used to prepare the device, providing a larger active area for the subsequent preparation of the device, and thus improving the yield of the device.

[0055] The following describes in detail the steps of the method for forming a semiconductor structure provided by the embodiment of the present disclosure:

[0056] In some embodiments provided by the present disclosure, Figure 4 As shown, in step S101 and step S102 , a substrate 100 is provided, and an isolation trench 300 is formed in the substrate 100 .

[0057] The substrate 100 may be a semiconductor substrate, for example, a silicon (Si) substrate, a germanium (Ge) substrate, a silicon-germanium (GeSi) substrate, SOI (Silicon On Insulator) or GOI (Germanium On Insulator). In some embodiments, the semiconductor substrate may also be a substrate comprising other elemental semiconductors or compound semiconductors, for example, silicon carbide (SiC), indium phosphide (InP) or gallium arsenide (GaAs). The embodiments provided in the present disclosure are described using the substrate 100 as a substrate comprising silicon (Si) ions as an example. Of course, for other types of substrates, corresponding modifications or improvements can be made to the embodiments of the present disclosure, all of which are within the scope of protection of the present disclosure and are not specifically limited by the present disclosure.

[0058] An isolation trench 300 is formed in the substrate 100. A trench that passes through one side of the substrate 100 can be formed in the substrate 100 by etching, and the opening of the trench is located on one side of the substrate 100. For example, a mask layer is formed on the substrate 100, and the substrate 100 is subjected to an etching process to form a plurality of isolation trenches 300 on the substrate 100. The etching process can be dry etching or wet etching, and of course, other etching process methods can also be used. The plurality of isolation trenches 300 can be distributed in an array on the substrate 100, or the number and distribution of the isolation trenches 300 can be selected according to the manufacturing process of the device. The depth of the isolation trench 300 in the direction perpendicular to the substrate 100 can be set according to actual process requirements.

[0059] In some embodiments, due to limitations of the fabrication process, the isolation trench 300 formed on the substrate 100 may be V-shaped or quasi-V-shaped, i.e., the width of the cross section at the bottom of the isolation trench 300 in a direction parallel to the size of the substrate 100 is smaller than the width of the cross section at the top of the isolation trench 300. In other embodiments, the isolation trench 300 formed on the substrate 100 may be U-shaped or quasi-U-shaped, i.e., the width of the cross section at the bottom of the isolation trench 300 in a direction parallel to the size of the substrate 100 is equal to the width of the cross section at the top of the isolation trench 300. Of course, the isolation trench 300 may also have other shapes, which are not limited to this.

[0060] In some embodiments provided by the present disclosure, Figure 5 As shown, in step S103 , a seed gas including silicon ions is introduced into the isolation trench 300 , and the seed gas adheres to the inner wall of the isolation trench 300 to form a seed layer 400 .

[0061] A seed gas is introduced into the isolation trench 300. The seed gas is a gas including silicon ions. For example, the seed gas can be dichlorosilane (H2SiCl) gas or other gas containing silicon ions. The seed gas is passed into the isolation trench 300 so that the seed gas covers the inner wall of the isolation trench 300. Specifically, the silicon ions in the seed gas adhere to the inner wall of the isolation trench 300, providing a seed layer 400 for the subsequent preparation of the target film 500. In the present disclosure, the seed layer 400 formed by the seed gas has a small decomposition amount and high stability at a specific process temperature. The thickness of the seed layer 400 in the direction perpendicular to the inner wall of the isolation trench 300 is less than or equal to 1 nm (nanometer). For example, the thickness of the seed layer 400 can be 1 nm, 0.8 nm, 0.6 nm, 0.4 nm or 0.2 nm, etc.

[0062] In some embodiments, the seed gas may be introduced into the isolation trench 300 for a period of 5 minutes to 15 minutes, for example, 5 minutes, 6 minutes, 7 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, or 15 minutes, to ensure that the seed gas adheres to various portions of the inner wall of the isolation trench 300. In the present disclosure, the seed layer 400 primarily refers to a film layer formed by silicon ions in the seed gas adhering to the inner wall of the isolation trench 300. Due to the free nature of silicon ions, the seed layer 400 may be a continuous film layer or a discontinuous film layer, that is, the seed layer 400 is a film layer composed of silicon ions.

[0063] In the present disclosure, the seed layer 400 is mainly attached to the top of the isolation trench 300, that is, the seed layer 400 is mainly attached to the inner wall of the isolation trench 300 near the opening, and the target film 500 is deposited on the seed layer 400, that is, the target film 500 is mainly formed above the isolation trench 300. The target film 500 can be formed in one step through the seed layer 400 to increase the effective area of ​​the active area.

[0064] In some embodiments provided by the present disclosure, Figure 6 As shown, in step S104, a silicon-containing gas is introduced into the seed layer 400, and the silicon-containing gas decomposes into a solid substance and a first gas. The solid substance includes silicon ions, and the solid substance is covered on the surface formed by the seed layer 400 and the inner wall of the isolation groove 300 to form a target film 500.

[0065] After the silicon-containing gas is introduced into the seed layer 400, under predetermined reaction conditions, the silicon-containing gas may undergo a gas phase reaction in the isolation trench 300. The gas phase reaction may include a primary reaction and a secondary reaction. A gas phase reaction refers to a chemical reaction in which all reactants are in a gaseous state.

[0066] After the silicon-containing gas is introduced into the seed layer 400, a primary reaction occurs, under reaction conditions of a temperature of 300°C to 500°C and a pressure of 0.5 torr to 3 torr, where the silicon-containing gas decomposes into a second gas and a third gas, both of which contain silicon ions. The silicon-containing gas may include disilane (Si2H6), the second gas may include monosilane (SiH4), and the third gas may include silylene (SiH2).

[0067] The reaction temperature is 300° C. to 500° C., for example, 300° C., 320° C., 340° C., 360° C., 380° C., 400° C., 420° C., 440° C., 460° C., 480° C., or 500° C. The reaction pressure is 0.5 torr to 3 torr, for example, 0.5 torr, 1 torr, 1.5 torr, 2 torr, 2.5 torr, or 3 torr.

[0068] In some specific embodiments provided in the present disclosure, the reaction conditions of temperature 420°C and pressure 1 torr are used as an example to illustrate that silicon-containing gas is introduced into the seed layer 400. Under the above reaction conditions, disilane (Si2H6) undergoes a first-order reaction and decomposes into monosilane (SiH4) and silylene (SiH2). The reaction process is as follows:

[0069] After the silicon-containing gas is introduced into the seed layer 400, a secondary reaction occurs, in which the third gas decomposes into a solid substance and a first gas at a temperature of 300°C to 500°C and a pressure of 0.5 torr to 3 torr. The first gas may include hydrogen (H2), the third gas may include silylene (SiH2), and the solid substance may include silicon (Si).

[0070] The reaction temperature is 300° C. to 500° C., for example, 300° C., 320° C., 340° C., 360° C., 380° C., 400° C., 420° C., 440° C., 460° C., 480° C., or 500° C. The reaction pressure is 0.5 torr to 3 torr, for example, 0.5 torr, 1 torr, 1.5 torr, 2 torr, 2.5 torr, or 3 torr.

[0071] In some specific embodiments provided herein, the reaction conditions of 420°C and 1 Torr are used as an example. Under these reaction conditions, silylene (SiH2) undergoes a secondary reaction, decomposing into silicon (Si) and hydrogen (H2). The reaction process is SiH2→Si↓+H2. The solid silicon (Si) generated in this reaction is adsorbed on the surface of the seed layer 400, forming a silicon (Si)-containing film layer.

[0072] In the primary reaction, the gas produced after the decomposition of the silicon-containing gas includes a second gas. Under reaction conditions of a temperature of 300°C to 500°C and a pressure of 0.5 torr to 3 torr, the second gas decomposes into a third gas and a first gas. The second gas may include monosilane (SiH4), the third gas may include silylene (SiH2), and the first gas may include hydrogen (H2).

[0073] The reaction temperature is 300° C. to 500° C., for example, 300° C., 320° C., 340° C., 360° C., 380° C., 400° C., 420° C., 440° C., 460° C., 480° C., or 500° C. The reaction pressure is 0.5 torr to 3 torr, for example, 0.5 torr, 1 torr, 1.5 torr, 2 torr, 2.5 torr, or 3 torr.

[0074] In some specific embodiments provided in the present disclosure, the reaction conditions of temperature 420°C and pressure 1 torr are used as an example to illustrate. Under the above reaction conditions, monosilane (SiH4) undergoes gas phase decomposition to decompose into monosilylene (SiH2) and hydrogen (H2). The reaction process is as follows: Under the above reaction conditions, silylene (SiH2) generated by the decomposition of monosilane (SiH4) can continue to undergo a secondary reaction, decomposing silylene (SiH2) to generate silicon (Si) and hydrogen (H2). The reaction process is SiH2→Si↓+H2. The solid silicon (Si) generated in this reaction is also adsorbed on the surface of the seed layer 400 to form a silicon (Si)-containing film layer.

[0075] Furthermore, under preset reaction conditions, the second gas can also directly decompose into a solid substance and the first gas. Specifically, under reaction conditions of 520°C to 750°C and a pressure of 0.5 torr to 3 torr, the second gas decomposes into a solid substance and the first gas. The first gas can include hydrogen (H2), the second gas can include monosilane (SiH4), and the solid substance can include silicon (Si).

[0076] The reaction temperature is 520° C. to 750° C., for example, 520° C., 540° C., 560° C., 580° C., 600° C., 620° C., 640° C., 680° C., 700° C., 720° C., 740° C., or 750° C. The reaction pressure is 0.5 torr to 3 torr, for example, 0.5 torr, 1 torr, 1.5 torr, 2 torr, 2.5 torr, or 3 torr.

[0077] In some specific embodiments provided herein, reaction conditions of 520°C and 1 torr are used as an example. Under these reaction conditions, monosilane (SiH4) decomposes to produce silicon (Si) and hydrogen (H2), and the reaction process is SiH4→Si↓+H2. The solid silicon (Si) produced in this reaction is also adsorbed on the surface of the seed layer 400, forming a silicon (Si)-containing film layer. In this reaction, since the reaction temperature for the decomposition of monosilane (SiH4) to produce silicon (Si) and hydrogen (H2) is higher than the reaction temperature for the decomposition of silylene (SiH2) to produce silicon (Si) and hydrogen (H2), and the lower the temperature, the slower the decomposition of monosilane (SiH4) to produce silicon (Si) and hydrogen (H2), the primary reaction to produce the solid substance is the decomposition of silylene (SiH2) to produce silicon (Si) and hydrogen (H2), that is, the solid substance is primarily produced by the decomposition of the third gas.

[0078] Through the reaction process described in the above embodiment, the silicon-containing gas decomposes to generate a solid substance, which is coated on the surface formed by the seed layer 400 and the inner wall of the isolation trench 300 to form the target film 500. The solid substance may include silicon (Si), that is, the target film 500 may be a film including silicon (Si). Since the substrate 100 may also be a substrate 100 including silicon (Si), the formed target film 500 has the same properties as the substrate 100. By forming the target film 500 on the inner wall of the isolation trench 300, and the target film 500 having a certain thickness in a direction parallel to the substrate 100, the target film 500 fills the inner sidewall of the isolation layer to increase the surface area of ​​the side of the substrate 100 where the isolation trench 300 is formed, that is, the area of ​​the active area of ​​the substrate 100 is increased, providing a larger active area for subsequent device fabrication, and improving the device yield. Exemplarily, the thickness of the target film 500 may increase along the opening direction of the isolation trench 300 to increase the surface area of ​​the side of the substrate 100 where the isolation trench 300 is formed.

[0079] In some embodiments provided in the present disclosure, when the isolation trench 300 is formed on the substrate 100 in a "V"-shaped or "V-like" shape, a target film is formed on the inner side wall of the isolation trench 300 by the above-mentioned formation method, and the isolation trench 300 can be filled in a direction parallel to the substrate 100 by the target film to increase the surface area of ​​the side of the substrate 100 where the isolation trench 300 is formed. After the target film is formed, the isolation trench 300 can be "U"-shaped or "U-like". Of course, according to actual needs, the thickness of the target film at the opening of the isolation trench 300 can be further increased, so that the isolation trench 300 is in an inverted "V"-shaped or "V-like" shape. The thickness and shape of the target film can be selected according to actual design requirements and are not specifically limited here.

[0080] In a specific embodiment provided by the present disclosure, the thickness and shape of the target film 500 can be controlled by controlling the reaction time. In order to increase the thickness of the target film along the opening direction of the isolation trench 300, the solid material can be controlled to be deposited first in the top area of ​​the isolation trench 300. Since the depth and width of the isolation trench 300 are relatively large, the silicon-containing gas extends from the top to the bottom of the isolation trench 300. Therefore, the above-mentioned reaction usually occurs first at the top of the isolation trench 300. Therefore, by controlling the reaction time within a certain range, the thickness of the target film can be increased along the opening direction of the isolation trench 300. The reaction time can be 3 minutes to 8 minutes, for example, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes or 8 minutes.

[0081] After the target thin film 500 is formed on the sidewalls of the isolation trench 300, the flow of the silicon-containing gas into the seed layer 400 is terminated, and the isolation trench 300 after the target thin film 500 is formed is evacuated to allow the residual gas after the reaction to be discharged from the isolation trench 300. The evacuation operation of the isolation trench 300 can be performed using equipment such as a vacuum pump. Of course, other methods can also be used to discharge the residual gas in the isolation trench 300.

[0082] In the actual preparation process, taking the substrate 100 as a silicon wafer as an example, the photoresist is a wafer on which a photoresist pattern has been formed on a planar wafer. In the disclosure, the photoresist can be a wafer on which a plurality of isolation grooves 300 have been formed on the substrate 100. In order to reduce the step coverage rate in the isolation groove 300, one or more of the following methods can be used: reducing the flow rate of the silicon-containing gas, increasing the reaction pressure, increasing the reaction temperature, etc.

[0083] The flow rate of the silicon-containing gas can be 800cc to 1200cc, for example, 800cc, 850cc, 900cc, 950cc, 1000cc, 1050cc, 1100cc, 1150cc, or 1200cc. The reaction temperature is 300°C to 500°C, for example, 300°C, 320°C, 340°C, 360°C, 380°C, 400°C, 420°C, 440°C, 460°C, 480°C, or 500°C. The reaction pressure is 0.5 torr to 3 torr, for example, 0.5 torr, 1 torr, 1.5 torr, 2 torr, 2.5 torr, or 3 torr. In a specific embodiment provided in the present disclosure, under the reaction conditions of a silicon-containing gas flow rate of 1050cc, a reaction temperature of 420°C, and a reaction pressure of 1 torr, the step coverage of the isolation trench 300 can be effectively reduced. Of course, the above reaction conditions are merely exemplary reaction conditions for reducing the step coverage of the isolation trench 300 provided by the present disclosure. Any combination of silicon-containing gas flow rate, reaction time, and reaction temperature within the above ranges can achieve the goal of reducing the step coverage of the isolation trench 300. Other reaction conditions can also be modified to reduce the step coverage of the isolation trench 300, which are not listed here.

[0084] In one embodiment provided by the present disclosure, the reaction in which the silicon-containing gas decomposes into the first gas and the second gas is a reversible reaction, that is, The reaction of the second gas decomposing into the third gas and the first gas is a reversible reaction, that is,

[0085] After the target film 500 is formed, the silicon-containing gas, the first gas, the second gas and the third gas in the isolation trench 300 are in dynamic equilibrium. Since the depth-to-width ratio of the isolation trench 300 is relatively large, some of the silicon-containing gas, the first gas, the second gas and the third gas are adsorbed at the bottom of the isolation trench 300. Due to the instability of the third gas, the third gas will continue to decompose, and the solid matter generated by the decomposition will be deposited at the bottom of the isolation trench 300, resulting in a decrease in the depth-to-width ratio of the isolation trench 300, which in turn causes short circuits in subsequent devices.

[0086] To avoid this phenomenon, the two reversible reactions described above are utilized. Under preset reaction conditions, a first gas is introduced into isolation trench 300. As the pressure of the first gas increases, the reversible reaction proceeds in the reverse direction, causing the remaining third gas at the bottom of isolation trench 300 to react with the first gas to generate the second gas. Simultaneously, the second gas can also react with the remaining third gas in isolation trench 300 to generate a silicon-containing gas. After the third gas is removed from isolation trench 300, the remaining gas in isolation trench 300 can be evacuated to prevent the deposition of solid matter at the bottom of isolation trench 300.

[0087] The above two reversible reactions can be carried out under the reaction conditions of a temperature of 300° C. to 500° C. and a pressure of 1.5 torr to 3 torr. For example, the reaction temperature can be 300° C., 320° C., 340° C., 360° C., 380° C., 400° C., 420° C., 440° C., 460° C., 480° C. or 500° C. For example, the reaction pressure can be 1.5 torr, 1.8 torr, 2 torr, 2.3 torr, 2.5 torr, 2.8 torr or 3 torr. The time for continuously introducing the first gas can be 1 min 30s to 3 min 30s, for example, 1 min 30s, 1 min 40s, 1 min 50s, 2 min, 2 min 10s, 2 min 20s, 2 min 30s, 2 min 40s, 2 min 50s, 3 min, 3 min 10s, 3 min 20s or 3 min 30s. The duration of evacuating the isolation trench 300 may be 10 seconds to 60 seconds, for example, 10 seconds, 20 seconds, 30 seconds, 40 seconds, 50 seconds, or 60 seconds. The flow rate of the first gas may be 0.1 slm (liters per minute) to 1.5 slm (liters per minute), for example, 0.1 slm, 0.3 slm, 0.5 slm, 0.7 slm, 0.9 slm, 1.1 slm, 1.3 slm, or 1.5 slm.

[0088] In one embodiment, hydrogen (H2) is introduced into the isolation trench 300 where the target film 500 has been formed under the reaction conditions of a temperature of 420°C and a pressure of 2 Torr, wherein the flow rate of hydrogen is 0.5 slm, so that a reversible reaction occurs in the isolation trench 300. and The reverse reaction of the reaction occurs, causing the silene (SiH2) in isolation trench 300 to react with hydrogen (H2) to produce monosilane (SiH4). Simultaneously, monosilane (SiH4) and silene (SiH2) in isolation trench 300 can also react to produce disilane (Si2H6). The disilane (Si2H6) and monosilane (SiH4) gases in isolation trench 300, particularly at the bottom of isolation trench 300, are evacuated. The evacuation time can be 30 seconds. The process of clearing the remaining gas in isolation trench 300 lasts for 2 minutes and 30 seconds.

[0089] In order to further remove the residual gas in the isolation groove 300 after the target film 500 is formed, the steps of introducing the first gas into the isolation groove 300 and evacuating the isolation groove 300 can be performed alternately and cyclically until a small amount of gas remains in the isolation groove 300 or the residual gas is completely removed. The above two steps can be cyclically performed 3 to 6 times, for example, 3, 4, 5 or 6 times. The specific number of cycles can be selected according to the amount of residual gas in the isolation groove 300. In a specific embodiment, Figure 7 As shown, at time t1, the target thin film 500 is formed in the isolation trench 300. During the time period t2-t3, the first gas is introduced four times, with the pressure of the first gas being equal each time. By repeatedly passing the first gas through the isolation trench 300, the pressure of the first gas within the isolation trench 300 is increased, allowing a reverse reaction to occur within the isolation trench 300, thereby removing any remaining gas within the isolation trench 300 and preventing solid matter from depositing at the bottom of the isolation trench 300.

[0090] The method for removing residual gas in the isolation trench 300 provided by the present disclosure can effectively prevent the deposition of solid substances such as silicon (Si) at the bottom of the isolation trench 300, thereby avoiding the occurrence of subsequent short circuits between devices caused by the deposition of solid substances at the bottom of the isolation trench 300, resulting in a smaller bottom width of the isolation trench 300, and at the same time preventing device manufacturing defects caused by insufficient depth of the isolation trench, further improving the yield of the device.

[0091] It should be noted that although the steps of the method for forming a semiconductor structure in the present disclosure are described in a specific order in the accompanying drawings, this does not require or imply that the steps must be performed in this specific order, or that all steps must be performed to achieve the desired results. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be decomposed into multiple steps.

[0092] The present disclosure also provides a semiconductor structure, such as Figure 6 As shown, the semiconductor structure includes a substrate 100 , an isolation trench 300 and a target film 500 .

[0093] The isolation trench 300 is located in the substrate 100, and the target film 500 is located on the inner sidewall of the isolation trench 300. The target film 500 includes silicon ions. The method for forming the target film 500 is as described above and will not be repeated here.

[0094] The substrate 100 may be a semiconductor substrate, for example, a silicon (Si) substrate, a germanium (Ge) substrate, a silicon-germanium (GeSi) substrate, a SOI (Silicon On Insulator), or a GOI (Germanium On Insulator). In some embodiments, the semiconductor substrate may also be a substrate including other elemental semiconductors or compound semiconductors, for example, silicon carbide (SiC), indium phosphide (InP), or gallium arsenide (GaAs).

[0095] The target film 500 includes the same ions as the substrate 100. For example, when the substrate 100 is a silicon substrate 100, the target film 500 may include silicon ions; when the substrate 100 is a silicon germanium substrate 100, the target film 500 may include silicon ions. In the above-described embodiment, the target film 500 is formed on the inner sidewalls of the isolation trench 300 to increase the surface area of ​​the side of the substrate 100 where the isolation trench 300 opens. This increases the area of ​​the active region on the substrate 100, providing a larger active region for subsequent device fabrication.

[0096] The thickness of the target film 500 increases along the opening direction of the isolation trench 300. Figure 6 In the direction indicated by the middle arrow, ie, the X direction, the opening direction of the isolation trench 300 may be perpendicular to the direction of the substrate.

[0097] Due to the limitations of the preparation process, the isolation trench 300 formed on the substrate 100 is generally "V"-shaped or quasi-"V"-shaped in the direction perpendicular to the substrate 100, resulting in a reduction in the surface area of ​​the active area distributed on the top of the isolation trench 300. In the present disclosure, the target film 500 increases along the opening direction of the isolation trench 300. In one embodiment, the target film 500 is attached to the inner wall of the isolation trench 300, so that the cross-section of the isolation trench 300 after the target film 500 is formed has the same width in the direction perpendicular to the substrate 100, that is, the isolation trench 300 after the target film 500 is formed is generally "U"-shaped or quasi-"U"-shaped in the direction perpendicular to the substrate 100.

[0098] In another embodiment, the target film 500 is attached to the inner wall of the isolation trench 300, so that the width of the cross section of the isolation trench 300 after the target film 500 is formed decreases from the bottom to the top of the isolation trench 300 in the direction perpendicular to the substrate 100, that is, the isolation trench 300 after the target film 500 is formed is generally in an inverted "V" shape or a quasi-inverted "V" shape in the direction perpendicular to the substrate 100.

[0099] The target film 500 provided in the above two embodiments can both achieve the purpose of increasing the active area of ​​the substrate 100. Of course, the thickness of the target film 500 provided in the present disclosure can be selected according to actual process requirements, and the present disclosure does not make any specific restrictions.

[0100] The semiconductor structure provided by the present disclosure forms a target thin film 500 on the inner wall of the isolation trench 300. The semiconductor structure has a larger active area, which can improve the manufacturing quality of subsequent devices and increase the yield of the devices.

[0101] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the present disclosure being indicated by the appended claims.

Claims

1. A method for forming a semiconductor structure, characterized in that: include: providing a substrate, wherein the substrate is a semiconductor substrate; forming an isolation trench in the substrate; introducing a seed gas into the isolation trench, wherein the seed gas includes silicon ions, and the seed gas adheres to an inner wall of the isolation trench to form a seed layer; A silicon-containing gas is introduced into the seed layer, and the silicon-containing gas decomposes into a solid substance and a first gas. The solid substance includes silicon ions. The solid substance is covered on the surface jointly formed by the seed layer and the inner wall of the isolation groove to form a target film, so as to increase the surface area of ​​the side of the substrate where the isolation groove is formed.

2. The method for forming a semiconductor structure according to claim 1, wherein: The seed gas is dichlorosilane gas, and the solid matter is silicon atomic particles.

3. The method for forming a semiconductor structure according to claim 1, wherein: The thickness of the target film increases gradually in a direction away from the substrate.

4. The method for forming a semiconductor structure according to claim 1, wherein: Before the silicon-containing gas is decomposed into the solid matter and the first gas, the method includes: Under reaction conditions of a temperature of 300° C. to 500° C. and a pressure of 0.5 torr to 3 torr, the silicon-containing gas decomposes into a second gas and a third gas, both of which contain silicon ions.

5. The method for forming a semiconductor structure according to claim 4, wherein: The silicon-containing gas includes disilane, the first gas includes hydrogen, the second gas includes monosilane, and the third gas includes silene.

6. The method for forming a semiconductor structure according to claim 5, wherein: After the silicon-containing gas is decomposed into the second gas and the third gas, the method includes: Under reaction conditions of a temperature of 300° C. to 500° C. and a pressure of 0.5 torr to 3 torr, the second gas is decomposed into the third gas and the first gas.

7. The method for forming a semiconductor structure according to claim 6, wherein: After the second gas is decomposed into the third gas and the first gas, the method includes: Under reaction conditions of a temperature of 300° C. to 500° C. and a pressure of 0.5 torr to 3 torr, the third gas decomposes into the solid matter and the first gas.

8. The method for forming a semiconductor structure according to claim 5, wherein: After the silicon-containing gas is decomposed into the second gas and the third gas, the method includes: Under reaction conditions of a temperature of 520° C. to 750° C. and a pressure of 0.5 torr to 3 torr, the second gas decomposes into the solid matter and the first gas.

9. The method for forming a semiconductor structure according to claim 4, wherein: The isolation groove is vacuumed after the target film is formed, comprising: introducing the first gas into the target film; Under reaction conditions of a temperature of 300° C. to 500° C. and a pressure of 1.5 torr to 3 torr, the third gas and the first gas are reacted to generate the second gas, and / or the second gas and the third gas are reacted to generate the first gas; The isolation groove is evacuated to allow the generated second gas and / or the generated third gas to be discharged from the isolation groove.

10. A semiconductor structure obtained by the method for forming a semiconductor structure according to any one of claims 1 to 9, characterized in that: include: substrate; an isolation trench located in the substrate; a target film, the target film being located on an inner sidewall of the isolation trench, the target film comprising silicon ions; The thickness of the target film increases gradually in a direction away from the substrate.

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