Deep groove filling method
By first forming a silicon nitride layer in the deep trench and generating silicon nuclei on its surface, the problem of uneven silicon layer growth was solved, achieving uniform deposition of the silicon layer in the deep trench and improving product performance.
Patent Information
- Application Number
- CN202410495378.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-23
- Publication Date
- 2025-10-24
AI Technical Summary
When using chemical vapor deposition in a vertical furnace, the growth thickness of the silicon layer in the deep trench is uneven, resulting in void defects and affecting product performance.
Atomic layer deposition (ALD) is used to form silicon nitride layers on the sidewalls and bottom of deep trenches. The silicon layers are then completely filled into the deep trenches using a deposition process. The time required to generate silicon nuclei on the surface of the silicon nitride layer is shorter than that of the silicon oxide layer, which reduces precursor aggregation and improves the uniformity of silicon layer growth.
Uniform deposition of silicon layers within deep trenches was achieved, avoiding void defects and improving product yield.
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Figure CN120834003A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of semiconductor manufacturing, and in particular to a deep trench filling method. BACKGROUND
[0002] Compared with the equipment for chemical vapor deposition on a single wafer, the chemical vapor deposition in a vertical furnace can be used for mass production of wafers to improve production efficiency.
[0003] However, when using a vertical furnace to fill a silicon layer in a deep trench in a silicon oxide (SiO2) layer on the surface of a wafer, the precursor generated by the silicon source (such as silane) reacts on the surface of the SiO2 for too long to incubate Si crystal nuclei, which causes the precursor to be unevenly aggregated on the surface of the silicon oxide layer, and thus the growth thickness of the silicon layer in each direction in the deep trench is different, the deep trench is prematurely sealed, and void defects are formed in the silicon layer, which affects the final performance of the product.
[0004] Therefore, there is a need for a deep trench filling method suitable for a vertical furnace, so that the silicon layer can be uniformly deposited in the deep trench. SUMMARY
[0005] The purpose of the present application is to provide a deep trench filling method, so that the silicon layer can be uniformly deposited in the deep trench, and void defects in the silicon layer are avoided, which affects the yield of the product.
[0006] The deep trench filling method of the present application includes: providing a substrate including a dielectric layer and a deep trench in the dielectric layer, the material of the dielectric layer including silicon oxide; forming a silicon nitride layer on the sidewall and bottom of the deep trench by using an atomic layer deposition process; and completely filling a silicon layer in the deep trench by using a deposition process.
[0007] In some embodiments, the thickness of the silicon nitride layer is greater than 0.1 nm and less than or equal to 10 nm.
[0008] In some embodiments, forming a silicon nitride layer on the sidewall and bottom of the deep trench by using an atomic layer deposition process includes: S1: introducing a first silicon source gas into a deposition chamber, so that the first silicon source gas is saturatedly adsorbed on the sidewall and bottom surface of the deep trench; S2: removing the first silicon source gas that is not adsorbed in the deposition chamber; S3: introducing a nitrogen source gas into the deposition chamber and ionizing the nitrogen source gas to generate plasma; S4: introducing an inert gas to remove waste gas in the deposition chamber; and S5: causing the first silicon source gas adsorbed on the sidewall and bottom surface of the deep trench to react with the plasma by atomic layer deposition to form the silicon nitride layer.
[0009] In some embodiments, the method further comprises repeating the steps S1-S5 until the thickness of the silicon nitride layer reaches a preset thickness.
[0010] In some embodiments, the first silicon source gas comprises at least one of hexachlorodisilane, trichlorosilane, dichlorosilane and silane.
[0011] In some embodiments, the nitrogen source gas comprises ammonia.
[0012] In some embodiments, the reaction temperature of the first silicon source gas and the plasma-induced atomic layer deposition reaction is 400-1000℃.
[0013] In some embodiments, the completely filling the deep trench with a silicon layer by a deposition process comprises: introducing a second silicon source gas into a deposition chamber, allowing the second silicon source gas to generate a precursor of the silicon layer in a gas phase, and allowing the precursor to react on the surface of the silicon nitride layer to generate the silicon layer.
[0014] In some embodiments, the second silicon source gas comprises at least one of disilane, bis(diethylamino)silane, bis(tert-butylamino)silane, tris(dimethylamino)silane and diisopropylaminosilane.
[0015] In some embodiments, the temperature of the reaction chamber during the process of introducing a second silicon source gas into a deposition chamber, allowing the second silicon source gas to generate a precursor of the silicon layer in a gas phase, and allowing the precursor to react on the surface of the silicon nitride layer to generate the silicon layer is 400-800℃.
[0016] In some embodiments, the width of the deep trench is 10-500nm, and the aspect ratio of the deep trench is 1-10.
[0017] The deep trench filling method provided by the embodiments of the present application has the following beneficial effects, but is not limited to the following:
[0018] Before filling the deep trench with a silicon layer, the present application deposits a silicon nitride layer on the surface of the deep trench by an atomic layer deposition process. The time for the precursor of the silicon source to react on the surface of the silicon nitride layer to generate a silicon nucleus is much less than the time for the precursor to generate a silicon nucleus on the surface of a silicon oxide layer. This reduces the local accumulation of the precursor, and makes the thickness of the silicon layer formed by the growth of the silicon nucleus in different directions of the deep trench consistent, thereby avoiding the formation of void defects in the silicon layer due to the early closure of the local area.
[0019] Further, forming a silicon nitride layer with a set thickness by multiple atomic layer deposition can reduce the roughness of the surface of the silicon nitride layer, and further reduce the local accumulation of the precursor.
[0020] In addition, the second silicon source gas capable of generating the precursor in the gas phase is used to improve the uniformity of the precursor distribution on the surface of the silicon nitride layer when the silicon layer is deposited, further improve the consistency of the deposition rate of the silicon layer in different directions of the deep trench, and avoid the occurrence of void defects in the silicon layer. BRIEF DESCRIPTION OF DRAWINGS
[0021] The following drawings in detail describe the exemplary embodiments disclosed in the present application. The same reference signs in the several views of the drawings represent similar structures. Those skilled in the art will understand that these embodiments are non-limiting, exemplary embodiments, and the drawings are only for the purpose of illustration and description, and are not intended to limit the scope of the present application, and other embodiments can also achieve the same purpose of the invention in the present application. It should be understood that the drawings are not drawn to scale. Among them:
[0022] Figure 1 is a schematic view of a deep trench structure;
[0023] Figures 2-3 is a process schematic view of filling a silicon layer into Figure 1 the deep trench shown.
[0024] Figures 4-6 is a schematic view of the structure of each step of the deep trench filling method according to the embodiments of the present application;
[0025] Figure 7 is a flow chart of the method of depositing a silicon nitride layer according to the embodiments of the present application. DETAILED DESCRIPTION
[0026] The following description provides specific application scenarios and requirements of the present application, which is to enable those skilled in the art to manufacture and use the content in the present application. Various local modifications of the disclosed embodiments are obvious to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of the present application. Therefore, the present application is not limited to the embodiments shown, but is consistent with the widest scope of the claims.
[0027] Figure 1 is a schematic view of a deep trench structure; Figures 2-3 is a process schematic view of filling a silicon layer into Figure 1 the deep trench shown.
[0028] Reference Figures 1-3In the process of filling the silicon layer 30 into the deep trench 20 in the dielectric layer 10 by using chemical vapor deposition, generally, a silicon source gas is introduced into a deposition chamber, the silicon source gas first generates a precursor, the precursor reacts on the surface of the deep trench 20 to generate a silicon nucleus, the silicon nucleus continuously grows, and finally forms the silicon layer 30 filling the deep trench. The material of the dielectric layer 10 includes SiO2, and the silicon layer 30 is polysilicon.
[0029] With reference to Figures 2-3 When the silicon source gas is silane (SiH4), the silane first adheres to the surface of the deep trench 20, and then generates a precursor. Since the time for the precursor to react on the surface of the deep trench 20 to generate the silicon nucleus is relatively long, the precursor is accumulated on the surface of the deep trench 20, and then the silicon nucleus is unevenly distributed on the surface of the deep trench 20, so that the silicon layer 30 formed by the growth of the silicon nucleus in different directions of the deep trench 20 has different thicknesses. The silicon layer 30 is not completely filled in the deep trench 20, and the silicon layer 30 grown in the direction perpendicular to the sidewall of the deep trench 20 is locally contacted to form a gap 40, so that the internal gap defect of the silicon layer 30 is generated, and the final performance of the product is affected.
[0030] Therefore, there is a need for a deep trench filling method to avoid the internal gap defect of the silicon layer filling the deep trench, and the method is suitable for a vertical furnace chemical vapor deposition device.
[0031] The application provides a deep trench filling method, which comprises the following steps: providing a substrate, the substrate comprising a dielectric layer and a deep trench in the dielectric layer, and the material of the dielectric layer comprising silicon oxide; forming a silicon nitride layer with uniform thickness distribution and a surface roughness range of 0-2 nm on the sidewall and bottom of the deep trench by using an atomic layer deposition process; and completely filling a silicon layer in the deep trench by using a deposition process.
[0032] The deep trench filling method provided by the application first deposits a silicon nitride layer on the surface of the deep trench by using an atomic layer deposition process. The time for the precursor of the silicon source to react on the surface of the silicon nitride layer to generate a silicon nucleus is much shorter than the time for directly generating a silicon nucleus on the surface of the dielectric layer. The surface roughness range of the silicon nitride layer is 0-2 nm, the accumulation of the precursor on the surface of the silicon nitride layer is reduced, the thickness of the silicon layer formed by the growth of the silicon nucleus in different directions of the deep trench is consistent, and the gap defect of the silicon layer due to the early closure of the local area is avoided.
[0033] The deep trench filling method provided by the application will be described in detail below in combination with embodiments and drawings.
[0034] With reference to Figures 4-6The embodiment of the present application provides a deep trench filling method, which comprises the following steps: providing a substrate, wherein the substrate comprises a medium layer 100 and a deep trench 200 in the medium layer 100; forming a silicon nitride layer 400 with uniform thickness distribution and surface roughness in the range of 0-2 nm on the sidewall and bottom of the deep trench 200 by using an atomic layer deposition process; and completely filling a silicon layer 300 in the deep trench 200 by using a deposition process.
[0035] The substrate further comprises a semiconductor substrate, the medium layer 100 is located on the surface of the semiconductor substrate, the semiconductor substrate comprises silicon, silicon germanium and silicon on insulator, and in some embodiments, planar and three-dimensional COMS active or passive devices can be formed in the semiconductor substrate, and the deep trench is used for polysilicon filling.
[0036] In some embodiments, the material of the medium layer 100 comprises silicon oxide (SiO2), and the forming method of the deep trench 200 is, for example, wet etching or dry etching of the medium layer 100, and the present application does not limit the forming method of the deep trench 200. In some embodiments, the width of the deep trench 200 is 10-500 nm, and the aspect ratio of the deep trench 200 is 1-10.
[0037] In some embodiments, the atomic layer deposition process is used to form the silicon nitride layer 400 on the sidewall and bottom of the deep trench 200, which comprises the following steps: S1, introducing a first silicon source gas into a deposition cavity, so that the first silicon source gas is saturatedly adsorbed on the sidewall and bottom surface of the deep trench 200; S2, removing the first silicon source gas not adsorbed in the deposition cavity; S3, introducing a nitrogen source gas into the deposition cavity, and ionizing the nitrogen source gas to generate plasma; S4, introducing an inert gas to remove waste gas in the deposition cavity; and S5, making the first silicon source gas adsorbed on the sidewall and bottom surface of the deep trench 200 react with the plasma by atomic layer deposition, to form the silicon nitride layer 400.
[0038] Firstly, a first silicon source gas is introduced into a deposition cavity, so that the first silicon source gas is saturatedly adsorbed on the sidewall and bottom surface of the deep trench 200. In some embodiments, the first silicon source gas comprises at least one of hexachlorodisilane, trichlorosilane, dichlorosilane and silane. In order to make the first silicon source gas saturatedly adsorbed on the sidewall and bottom surface of the deep trench 200, in some embodiments, the flow rate of the first silicon source gas introduced is 0-1 SLM.
[0039] Then, the first silicon source gas not adsorbed in the deposition cavity is removed. The method for removing the first silicon source gas not adsorbed in the deposition cavity is purging the first silicon source gas not adsorbed by using nitrogen. The purpose of removing the first silicon source gas not adsorbed in the deposition cavity is to realize monolayer deposition.
[0040] Then, a nitrogen source gas is introduced into the deposition cavity, and the nitrogen source gas is ionized to generate plasma. In some embodiments, the nitrogen source gas includes ammonia, and in some embodiments, the flow rate of the nitrogen source gas is 0-5 SLM.
[0041] In some embodiments, ionizing the nitrogen source gas to generate plasma includes:
[0042] The ammonia is ionized into plasma by a radio frequency tube pressurization method:
[0043] NH3→NH2*+H*,
[0044] In some embodiments, the power of the radio frequency tube is 100-200 W.
[0045] The plasma has high chemical activity, and deposition reaction can occur at a low temperature.
[0046] After that, an inert gas is introduced into the reaction cavity to remove waste gas in the deposition cavity. The waste gas includes HCl and NH4Cl generated in the process of chemical deposition of the plasma and the first silicon source gas. Removing the waste gas can be beneficial to realize monolayer deposition. In some embodiments, the inert gas includes at least one of nitrogen and argon.
[0047] The reaction temperature for the atomic layer deposition reaction between the first silicon source gas adsorbed on the sidewall and the bottom surface of the deep trench 200 and the plasma to form the silicon nitride layer 400 is 400-1000°C. Alternatively, the reaction temperature is 400, 500, 800, or 1000°C. In some embodiments, the pressure in the deposition cavity when the first silicon source gas reacts with the plasma is 0-5 Torr.
[0048] In some embodiments, when the first silicon source gas is silane and the nitrogen source gas is ammonia, the chemical reaction formula of the reaction between the silane and the ammonia is as follows:
[0049] SiH4+NH3→Si3N4+H2
[0050] In some embodiments, when the first silicon source gas is dichlorosilane and the nitrogen source gas is ammonia, the chemical reaction formula of the reaction between the dichlorosilane and the ammonia is as follows:
[0051] SiCl2H2 + NH3→ Si3N4+ H2+ HCl
[0052] In some embodiments, the thickness of the silicon nitride layer 400 is greater than 0.1 nm and less than or equal to 10 nm. In addition, since the Si-N bond of silicon nitride is more conducive to the nucleation of silicon crystal nucleus than the Si-O bond, when the precursor of the silicon crystal nucleus contacts the surface of the silicon nitride layer 400, the silicon crystal nucleus can be quickly reacted and incubated, avoiding local accumulation of the precursor, and making the growth thickness of the silicon crystal nucleus in different directions of the deep trench 200 uniform.
[0053] In some embodiments, the deep trench 200 filling method further comprises repeatedly performing the steps S1-S5 until the thickness of the silicon nitride layer 400 reaches a preset thickness. Specifically, the step of repeatedly performing the atomic layer deposition process is performed to sequentially form a first silicon nitride layer, a second silicon nitride layer, …, and an Nth silicon nitride layer on the sidewall and bottom of the deep trench 200, until the sum of the thicknesses of the first silicon nitride layer, the second silicon nitride layer, …, and the Nth silicon nitride layer reaches the preset thickness. In some embodiments, the thicknesses of the first silicon nitride layer, the second silicon nitride layer, …, and the Nth silicon nitride layer are greater than 0.1 nm and less than or equal to 0.3 nm. The step of repeatedly performing the atomic layer deposition process is to reduce the surface roughness of the silicon nitride layer. When the surface roughness of the silicon nitride layer is less than 1 nm, the effect of reducing the accumulation of the precursor by the silicon oxide layer is optimal. In some embodiments, the step of completely filling the silicon layer 300 in the deep trench 200 by the deposition process comprises: introducing a second silicon source gas into the deposition cavity, so that the second silicon source gas generates a precursor of the silicon layer in the gas phase, and the precursor reacts on the surface of the silicon nitride layer 400 to generate the silicon layer 300.
[0054] The second silicon source gas generates a precursor of the silicon layer 300 in the gas phase, and then the precursor adheres to the surface of the silicon nitride layer 400 to generate a silicon crystal nucleus, which gradually grows into the silicon layer 300. Compared with the silicon source gas that first adheres to the surface of the substrate to be deposited and then generates a precursor, the second silicon source gas first generates a precursor in the gas phase, and then the precursor adheres to the surface of the silicon nitride layer 400, which improves the uniformity of the precursor adhering to the surface of the silicon nitride layer 400, reduces the problem of precursor accumulation caused by too long time for the precursor to react to generate a silicon crystal nucleus, and further improves the uniformity of the deposition of the silicon layer 300 in different directions of the deep trench 200, thereby avoiding void defects in the silicon layer 300.
[0055] In some embodiments, the second silicon source gas comprises at least one of disilane, bis(diethylamino)silane, bis(tert-butylamino)silane, tris(dimethylamino)silane, and diisopropylaminosilane.
[0056] In some embodiments, when the second silicon source gas is introduced into the deposition cavity, the flow rate of the second silicon source gas is 0-1 SLM.
[0057] In some embodiments, when the second silicon source gas is introduced into the deposition cavity, the second silicon source gas generates a precursor of the silicon layer 300 in the gas phase, and the temperature in the deposition cavity is 400-800℃ during the reaction of the precursor on the surface of the silicon nitride layer 400 to generate the silicon layer 300.
[0058] In some embodiments, when the second silicon source gas is introduced into the deposition cavity, the second silicon source gas generates a precursor of the silicon layer 300 in the gas phase, and the pressure in the deposition cavity is 0-5 Torr during the reaction of the precursor on the surface of the silicon nitride layer 400 to generate the silicon layer 300.
[0059] The deep trench filling method provided by the embodiments of the present application has the following beneficial effects, but is not limited to the following:
[0060] Before filling the deep trench with a silicon layer, the embodiments of the present application first deposit a silicon nitride layer on the surface of the deep trench by atomic layer deposition process. The time for the precursor of the silicon source to react on the surface of the silicon nitride layer to generate a silicon nucleus is much less than the time for the silicon nucleus to be generated directly on the surface of the silicon oxide layer, and the surface roughness is in the range of 0-2 nm. The aggregation of the precursor on the surface of the deep trench is reduced, the thickness of the silicon layer formed by the growth of the silicon nucleus in different directions of the deep trench is consistent, and the void defects of the silicon layer due to the early closure of the local area are avoided.
[0061] In addition, when depositing the silicon layer, the embodiments of the present application use a second silicon source gas that can generate a precursor in the gas phase to improve the uniformity of the distribution of the precursor on the surface of the silicon nitride layer, and further improve the consistency of the deposition rate of the silicon layer in different directions of the deep trench, thereby avoiding the occurrence of void defects in the silicon layer.
[0062] It should be noted that different embodiments can have different beneficial effects, and in different embodiments, the beneficial effects that can be produced can be any one or a combination of the above, or any other beneficial effects that can be obtained.
[0063] The above has described the basic concepts, and it is obvious that the above detailed disclosure is only used as an example and does not limit the present specification. Although the present application is not explicitly described, those skilled in the art can make various modifications, improvements and corrections to the present application. Such modifications, improvements and corrections are suggested in the present specification, so such modifications, improvements and corrections still belong to the spirit and scope of the exemplary embodiments of the present application.
[0064] It should be noted that, in the description of the present application, unless specifically defined and limited otherwise, the terms "mounting", "connection", "connecting", "fixed", should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integrated; can be mechanical connection, can also be electrical connection; can be rotary connection, can also be sliding connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood in combination with the specific circumstances.
[0065] In addition, when the terms "first", "second", "third" and the like are used in the description of the present application to describe various features, these terms are used only to distinguish these features, and cannot be understood as indicating or implying the relevance between the features, the relative importance, or implicitly indicating the number of the indicated features.
[0066] In addition, the present application describes exemplary embodiments by referring to idealized exemplary cross-sectional and / or plan and / or perspective views. Therefore, differences from the illustrated shapes due to, for example, manufacturing techniques and / or tolerances are foreseeable. Therefore, the exemplary embodiments should not be interpreted as being limited to the shapes of the regions shown here, but should include deviations in the shapes caused by, for example, manufacturing. Therefore, the regions shown in the figures are essentially schematic, and the shapes are not intended to show the actual shape of the regions of the device nor to limit the scope of the exemplary embodiments.
[0067] Meanwhile, the present application uses specific words to describe the embodiments of the present application. As "one embodiment", "an embodiment", and / or "some embodiments" means a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that the "an embodiment" or "one embodiment" or "one alternative embodiment" mentioned in different places in the present application does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be properly combined.
[0068] Similarly, it should be noted that, in order to simplify the expression of the present application and to help understand one or more embodiments of the present application, in the foregoing description of the embodiments of the present application, various features are sometimes combined into one embodiment, figure or description thereof. However, this method of disclosure does not mean that the features required by the present application are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the disclosed single embodiment.
[0069] Finally, it should be understood that the embodiments described herein are merely exemplary of the principles of the application. Other embodiments can fall within the scope of the application. Thus, although the application has been described with respect to example embodiments, it will be recognized that the scope of the application encompasses alternatives that, in addition to the embodiments described, are also consistent with the principles of the application. Accordingly, the application is not to be restricted, except as by the appended claims and their equivalents.
Claims
1. A method of filling a deep trench, characterized by, The method comprises: providing a substrate, the substrate comprising a dielectric layer and a deep trench in the dielectric layer, the material of the dielectric layer comprising silicon oxide; forming a silicon nitride layer on the sidewall and bottom of the deep trench by an atomic layer deposition process; and completely filling the deep trench with a silicon layer by a deposition process. The thickness of the silicon nitride layer is greater than 0.1 nm and less than or equal to 10 nm.
2. The deep trench fill method of claim 1, wherein, The atomic layer deposition process comprises:
3. The deep trench filling method according to claim 1, wherein: S1: introducing a first silicon source gas into a deposition chamber, so that the first silicon source gas is saturatedly adsorbed on the sidewall and bottom surface of the deep trench; S2: removing the first silicon source gas that is not adsorbed in the deposition chamber; S3: introducing a nitrogen source gas into the deposition chamber and ionizing the nitrogen source gas to generate plasma; S4: introducing an inert gas to remove waste gas in the deposition chamber; and S5: causing the first silicon source gas adsorbed on the sidewall and bottom surface of the deep trench to react with the plasma to form the silicon nitride layer. The steps S1-S5 are performed multiple times until the thickness of the silicon nitride layer reaches a preset thickness.
4. The deep trench filling method according to claim 3, wherein: The first silicon source gas comprises at least one of hexachlorodisilane, trichlorosilane, dichlorosilane, and silane.
5. The deep trench filling method according to claim 3, wherein: The nitrogen source gas comprises ammonia.
6. The deep trench filling method according to claim 3, wherein: The reaction temperature of the atomic layer deposition reaction of the first silicon source gas and the plasma is 400-1000°C.
7. The deep trench filling method according to claim 3, wherein: The deposition process comprises:
8. The method of claim 1, wherein the deep trench filling process is characterized by, introducing a second silicon source gas into a deposition chamber, so that the second silicon source gas generates a precursor of the silicon layer in the gas phase, and the precursor reacts on the surface of the silicon nitride layer to generate the silicon layer. The second silicon source gas comprises at least one of disilane, bis(diethylamino)silane, bis(tert-butylamino)silane, tris(dimethylamino)silane, and diisopropylaminosilane.
9. The deep trench filling method according to claim 8, wherein: During the process of introducing the second silicon source gas into the deposition chamber, so that the second silicon source gas generates a precursor of the silicon layer in the gas phase, and the precursor reacts on the surface of the silicon nitride layer to generate the silicon layer, the temperature of the deposition chamber is 400-800°C.
10. The deep trench filling method according to claim 8, wherein: The width of the deep trench is 10-500 nm, and the aspect ratio of the deep trench is 1-10.
11. The method of claim 1, wherein,