Method for improving uniformity of thin film
By ion implantation of the substrate to form an amorphous layer and oxidizing it on the substrate and its amorphous layer, the problem of uneven thickness of the oxide layer on the trench is solved, and oxide layers with different thicknesses are formed in different regions of the substrate, which simplifies process steps and reduces costs and improves device performance.
Patent Information
- Application Number
- CN202311399833.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-26
- Publication Date
- 2025-04-29
AI Technical Summary
In the prior art, it is difficult to grow an oxide layer with uniform thickness on the trench, and when an oxide layer with different thicknesses is formed in different regions of the substrate, the process steps are complicated and the cost is high.
By ion implantation of the substrate, an amorphous layer is formed, and then the substrate and its amorphous layer are oxidized to form an oxide layer. This method can grow an oxide layer of uniform thickness on the trench and form an oxide layer of different thicknesses in different regions of the substrate.
Improves the uniformity of the oxide layer, simplifies process steps, reduces production costs, and thus improves device performance.
Smart Images
Figure CN119905392A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of semiconductor integrated circuits, and in particular to a method for improving film uniformity. Background Art
[0002] One of the foundations of semiconductor manufacturing technology is the thermal oxidation process. The oxide on the silicon wafer can be produced by thermal growth or deposition. In a heated environment, a thermally grown oxide layer can be obtained on the silicon wafer by externally supplying high-purity oxygen to react with the silicon substrate. The oxide layer has the functions of protecting the device from scratches and isolating contamination, limiting the isolation of charged carrier field areas, serving as a dielectric material in the gate oxide or storage unit structure, an injection mask in doping, and a dielectric layer of the metal conductive layer. To effectively realize these functions, the oxide layer needs to have a certain thickness, and the thickness requirements of the oxide layer in different areas of the substrate are different.
[0003] In the prior art, the following method is usually used to form oxide layers of different thicknesses: first, an oxide layer is formed on a substrate, then a nitride layer is formed on the oxide layer, then the nitride layer and the oxide layer in a partial area are removed by etching, and then the oxide layer is re-formed in the area, so that the thickness of the oxide layer in the two areas is different. However, when the thickness of the oxide layer is required to be more varied, the above method will seriously increase the process steps and increase the process cost.
[0004] In addition, when forming an oxide layer on the sidewall and bottom of the trench, it is usually desirable to form an oxide layer with good uniformity. However, due to the difference in growth rate between different crystal planes, the oxide film obtained on the trench surface may have poor uniformity. For example, the oxide thickness on the bottom surface of the trench is usually smaller than the oxide thickness on the sidewall surface of the trench, and the oxide thickness on the substrate surface is also smaller than the oxide thickness on the sidewall surface of the trench.
[0005] Therefore, how to grow an oxide layer with uniform thickness on the groove and how to form oxide layers with different thicknesses in different regions of the substrate on the basis of simplifying the process steps are technical problems that those skilled in the art need to solve. Summary of the invention
[0006] The purpose of the present invention is to provide a method for improving the uniformity of a thin film, which can grow an oxide layer with uniform thickness on a groove, thereby improving the uniformity of the oxide layer and improving the performance of a device.
[0007] In order to solve the above technical problems, the present invention provides a method for improving the uniformity of a thin film, comprising the following steps:
[0008] Providing a substrate, wherein a plurality of grooves are formed in the substrate, so that the substrate has a groove portion and a convex portion located between adjacent groove portions;
[0009] Performing ion implantation on the substrate to amorphize at least a portion of the surface of the protrusion to form an amorphous layer;
[0010] The substrate and the amorphous layer are oxidized to form an oxide layer on the surface of the protrusion.
[0011] Optionally, the thickness of the amorphous layer is controlled by controlling the process conditions of ion implantation, thereby controlling the thickness of the oxide layer.
[0012] Optionally, the thickness of the amorphous layer is controlled by controlling the energy and / or dose of ion implantation.
[0013] Optionally, the ions used in the ion implantation include at least one of silicon, germanium, arsenic, tin, gallium, indium, phosphorus, tellurium or bismuth.
[0014] Optionally, the ion implantation angle is -45° to 45°.
[0015] Optionally, the method of oxidizing the substrate includes dry oxygen oxidation, wet oxygen oxidation, plasma oxidation or an in-situ water vapor generation process.
[0016] Optionally, the substrate includes a first region and a second region, and ion implantation is performed on the substrate in the first region to amorphize the surface of the protrusion in the first region to form an amorphous layer;
[0017] The substrate and the amorphous layer are oxidized to form an oxide layer, and the oxide layer formed in the first region has a first thickness range.
[0018] Optionally, the method of performing ion implantation on the substrate in the first region includes:
[0019] forming a photoresist layer, wherein the photoresist layer covers the substrate;
[0020] exposing and developing the photoresist layer to form a patterned photoresist layer, wherein the patterned photoresist layer covers the second area and exposes the first area;
[0021] Using the patterned photoresist layer as a mask, ion implantation is performed on the first region.
[0022] Optionally, the method of performing ion implantation on the substrate in the first region includes:
[0023] forming a hard mask layer, wherein the hard mask layer covers the substrate;
[0024] Etching the hard mask layer to form a patterned hard mask layer, wherein the patterned hard mask layer covers the second region and exposes the first region;
[0025] Using the patterned hard mask layer as a mask, ion implantation is performed on the first region.
[0026] After forming the oxide layer in the first region, the method further includes:
[0027] Performing ion implantation on the substrate in the second region to amorphize the surface of the protrusion in the second region to form an amorphous layer;
[0028] The substrate and the amorphous layer are oxidized to form an oxide layer, the oxide layer formed in the second region has a second thickness range, and the second thickness range of the oxide layer in the second region is different from the first thickness range of the oxide layer in the first region.
[0029] In summary, in the method for improving the uniformity of a thin film provided by the present invention, a substrate is first provided, wherein a plurality of grooves are formed therein, so that the substrate has a groove portion and a convex portion located between adjacent groove portions; then, ion implantation is performed on the substrate to amorphize at least part of the surface of the convex portion to form an amorphous layer; then, the substrate and the amorphous layer are oxidized to form an oxide layer on the surface of the convex portion. The present invention forms an oxide layer on the surface of the convex portion by amorphization, so that the thickness of the oxide layer is basically the same or the thickness difference is significantly reduced, thereby improving the thickness difference of the oxide layer at different positions of the groove, improving the thickness difference of the oxide layer at different positions of the substrate, improving the uniformity of the oxide layer thickness, and improving the device performance.
[0030] Furthermore, an amorphous layer is formed by performing ion implantation on the substrate in the first region, the substrate and the amorphous layer in the first region are oxidized to form an oxide layer having a first thickness range, and then an amorphous layer is formed by performing ion implantation on the substrate in the second region, and the substrate and the amorphous layer in the second region are oxidized to form an oxide layer having a second thickness range. The first thickness range of the oxide layer in the first region is different from the second thickness range of the oxide layer in the second region, thereby forming oxide layers with different thicknesses in different regions of the substrate. Compared with the prior art, process steps are saved and manufacturing costs are reduced. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Those skilled in the art will appreciate that the accompanying drawings are provided for a better understanding of the present invention and do not constitute any limitation on the scope of the present invention.
[0032] Figure 1 Detailed description of the invention The invention is a flowchart of a method for improving thin film uniformity provided by an embodiment of the invention.
[0033] Figures 2 to 5It is a schematic diagram of the structure of each step of a method for improving thin film uniformity provided by an embodiment of the present invention.
[0034] Figure 6 It is a schematic diagram of the relationship between the thickness of the oxide layer and the ion implantation dose provided by an embodiment of the present invention.
[0035] In the attached figure:
[0036] 10 - substrate; 11 - trench; 12 - amorphous layer; 13 - oxide layer. DETAILED DESCRIPTION
[0037] In order to make the purpose, advantages and features of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis of each drawing is different, and sometimes different scales are used.
[0038] As used in the present invention, the singular forms "one", "an", and "the" include plural objects, unless the content clearly indicates otherwise. As used in the present invention, the term "or" is generally used in a sense that includes "and / or", unless the content clearly indicates otherwise. As used in the present invention, the term "several" is generally used in a sense that includes "at least one", unless the content clearly indicates otherwise. As used in the present invention, the term "at least two" is generally used in a sense that includes "two or more", unless the content clearly indicates otherwise. In addition, the terms "first", "second", and "third" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first", "second", and "third" may explicitly or implicitly include one or at least two of the features.
[0039] Figure 1 is a flow chart of a method for improving film uniformity provided by an embodiment of the present invention. Figure 1 As shown, the method for improving film uniformity provided in this embodiment includes the following steps:
[0040] Step S1: providing a substrate, wherein a plurality of grooves are formed in the substrate, so that the substrate has a groove portion and a convex portion located between adjacent groove portions;
[0041] Step S2: performing ion implantation on the substrate to amorphize at least a portion of the surface of the protrusion to form an amorphous layer;
[0042] Step S3: oxidizing the substrate and the amorphous layer to form an oxide layer on the surface of the protrusion.
[0043] The thickness of the oxide layer on the sidewall and upper surface of the protrusion or the oxide layer on the bottom surface of the groove is substantially the same, or the thickness difference becomes smaller, that is, the thickness is more uniform.
[0044] Figures 2 to 5 FIG. 1 is a schematic diagram of the structure of each step of a method for improving film uniformity provided by an embodiment of the present invention. Figure 1 and Figures 2 to 5 The method for improving thin film uniformity provided by the embodiment of the present invention is described in detail.
[0045] In step S1, refer to Figure 2 As shown, a substrate 10 is provided, in which a plurality of grooves 11 are formed, so that the substrate has a groove portion and a convex portion located between adjacent groove portions.
[0046] In this embodiment, the material of the substrate 100 may be silicon, germanium, silicon germanium, silicon carbide, gallium arsenide, indium gallium, etc., or may be silicon on insulator, germanium on insulator; or may be other materials, such as III-V compounds such as gallium arsenide. In this embodiment, the material of the substrate 100 is single crystal silicon.
[0047] A plurality of grooves 11 are formed in the substrate 10, and the grooves 11 can be formed in both the first region I and the second region II. Exemplarily, a photoresist layer can be first formed on the substrate 10, and the photoresist layer covers the substrate 10. Then, the photoresist layer is exposed and developed to form a patterned photoresist layer, and the patterned photoresist layer exposes the substrate 10 in the region where the grooves are predetermined to be formed. Then, the substrate 10 is etched using the patterned photoresist layer as a mask to form a plurality of grooves 11 of a predetermined depth. Finally, the patterned photoresist layer is removed. Of course, the method for forming the grooves 11 is not limited thereto. The grooves 11 can be ordinary shallow grooves or high aspect ratio grooves, and the present invention is not limited thereto.
[0048] After forming the plurality of grooves 11, the substrate 10 has groove portions and convex portions located between adjacent groove portions. Figure 2 As shown, the protrusion has a side wall and an upper surface, the groove has a side wall and a bottom surface, and the adjacent protrusions and grooves share the same side wall.
[0049] In this embodiment, the substrate 10 can be divided into the first region I and the second region II according to the thickness of the oxide layer to be formed. The first region I and the second region II can be regions for forming different devices, and an isolation structure can be formed between the first region I and the second region II. Of course, the substrate 10 can also be divided into three or more regions, which can be divided according to the actual required thickness of the oxide layer. For example, if there are two requirements for the thickness of the oxide layer, it is divided into two regions.
[0050] In step S2, please refer to Figure 3 As shown, ion implantation is performed on the substrate 10 to amorphize at least a portion of the surface of the protruding portion of the substrate 10 to form an amorphous layer 12 .
[0051] In this embodiment, the single crystal silicon layer on at least part of the surface of the protrusion is converted into the amorphous layer 12 through ion implantation, specifically, into an amorphous silicon layer. The oxidation rate of the amorphous layer 12 is different from the oxidation rate of the substrate 10, and the original oxidation rates at different positions of the groove 11 are different. Through the formation of the amorphous layer 12, an oxide layer with uniform thickness is formed on the groove 11 in the subsequent oxidation process.
[0052] In this embodiment, ion implantation is performed on the substrate in the first region I, so that the surface of the protrusion is amorphized to form an amorphous layer 12. Specifically, the upper surface of the protrusion and the bottom surface of the groove are amorphized to form the amorphous layer 12, while the amorphous layer 12 is not formed on the sidewall of the protrusion. Of course, in other embodiments, part of the sidewall of the protrusion will also be amorphized to form the amorphous layer 12, but the degree of amorphization is less than that of the upper surface of the protrusion, or the thickness of the amorphous layer 12 formed on part of the sidewall of the protrusion is much less than the thickness of the amorphous layer 12 formed on the upper surface of the protrusion.
[0053] The ions used in the ion implantation include at least one of silicon (Si), germanium (Ge), arsenic (As), tin (Sn), gallium (Ga), indium (In), phosphorus (P), tellurium (Te) or bismuth (Bi). The thickness of the amorphous layer 12 can be controlled by controlling the process conditions of the ion implantation, so as to control the thickness of the subsequently formed oxide layer. That is, the thickness of the amorphous layer 12 is controlled by controlling the process conditions of the ion implantation, and the thickness of the subsequently formed oxide layer is controlled by the thickness of the amorphous layer 12. In this embodiment, the thickness of the amorphous layer 12 can be controlled by controlling the energy and / or dose of the ion implantation. For example, the thickness of the amorphous layer 12 can be controlled by controlling the energy of the ion implantation, or controlling the dose of the ion implantation, or controlling the energy and dose of the ion implantation. Exemplarily, the energy of the ion implantation can be 1Kev to 10Kev, and the dose of the ion implantation can be 0.5e14 / cm 2 ~10e14 / cm 2 , but not limited thereto. The thickness of the amorphous layer 12 can be increased or decreased by increasing or decreasing the energy and / or dose of ion implantation. The angle of ion implantation is -45° to 45°, which refers to the angle between the direction of ion implantation and Figure 3 The vertical angle of the ion implantation method is preferably 0°.
[0054] In this embodiment, please refer to Figure 3 As shown, the method for performing ion implantation on the substrate 10 in the first region I includes: firstly forming a photoresist layer, the photoresist layer covering the substrate 10, then exposing and developing the photoresist layer to form a patterned photoresist layer, the patterned photoresist layer covering the second region II, exposing the first region I ( Figure 3 The figure is only a schematic diagram, and the second region II is covered in the form of a mask. Then, the patterned photoresist layer is used as a mask to perform ion implantation on the first region II.
[0055] Of course, in another embodiment, before forming the photoresist layer, a hard mask layer may be formed on the substrate 10, the hard mask layer being, for example, a silicon nitride layer, the hard mask layer covering the substrate 10, and the photoresist layer covering the hard mask layer. After forming the patterned photoresist layer, the hard mask layer is etched using the patterned photoresist layer as a mask to form a patterned hard mask layer, wherein the patterned hard mask layer exposes the first region I and covers the second region II. Then, the patterned photoresist layer is removed, and ion implantation is performed using the patterned hard mask layer as a mask.
[0056] Please refer to Figure 3As shown, the first region I is subjected to ion implantation to form the amorphous layer 12 on the upper surface of the protrusion and the bottom surface of the groove.
[0057] In step S3, please refer to Figure 4 As shown, the substrate 10 and the amorphous layer 12 are oxidized to form an oxide layer 13 on the surface of the protrusion. The thickness of the oxide layer 12 on the sidewall and upper surface of the protrusion or the oxide layer 12 on the bottom surface of the groove portion is substantially the same, or the thickness difference becomes smaller, that is, the thickness is more uniform.
[0058] Please refer to Figure 3 and Figure 4 As shown, in the first region I, an amorphous layer 12 is formed on the upper surface of the protrusion and the bottom surface of the groove, and the side wall surface of the protrusion is a single crystal layer. The oxidation rate of the amorphous layer is greater than the oxidation rate of the single crystal layer, that is, the oxidation rate of the bottom surface of the groove and the upper surface of the protrusion is greater than the oxidation rate of the side wall surface of the protrusion. The side wall crystal plane of the protrusion is (110), the crystal plane of the upper surface is (100,), and the bottom crystal plane of the groove is (100). The oxidation rate of the crystal plane (110) is greater than the oxidation rate of the crystal plane (100), that is, in the absence of the amorphous layer 12, the oxidation rate of the side wall surface of the protrusion is greater than the oxidation rate of the upper surface of the protrusion and the bottom surface of the groove. Therefore, by selecting the thickness of the amorphous layer 12, the oxidation rates of the upper surface of the protrusion, the side wall of the protrusion and the bottom surface of the groove can be made the same, so that the oxide layer 13 with a first thickness range is finally formed in the first region I. That is, the thickness difference of the oxide layer 13 in the first region I becomes smaller, or the thickness is basically the same, and the thickness is basically the same means that the thickness difference at each location of the first region I is less than a range, and the range can be defined by engineering requirements. Thus, the thickness difference of the oxide layer 13 at different locations of the groove 11 is improved, and the thickness difference of the oxide layer 13 at different locations of the substrate in the first region I is also improved, the thickness uniformity of the oxide layer 13 in the first region I is improved, and the performance of the device is improved.
[0059] Of course, after forming the oxide layer 13, the patterned photoresist layer or the patterned hard mask layer is removed. Of course, the patterned photoresist layer or the patterned hard mask layer can also be removed after ion implantation, and then a barrier layer exposing the first region I and covering the second region II is formed, and then the first region I is oxidized, and the barrier layer is removed after the oxide layer 13 is formed.
[0060] In this embodiment, the method of oxidizing the substrate 10 includes dry oxygen oxidation, wet oxygen oxidation, plasma oxidation or in-situ steam generation (ISSG), but is not limited thereto. Preferably, the substrate 10 is subjected to an in-situ steam generation process to generate the oxide layer 13.
[0061] Please refer to Figure 5 As shown, after the oxide layer 13 is formed in the first region, the manufacturing method may further include:
[0062] Performing ion implantation on the substrate 10 in the second region II to amorphize the surface of the protrusion in the second region II to form an amorphous layer;
[0063] The substrate 10 and the amorphous layer are oxidized to form an oxide layer 13. The oxide layer 13 formed in the second region II has a second thickness range, and the second thickness range of the oxide layer 13 in the second region II is different from the first thickness range of the oxide layer 13 in the first region I.
[0064] The oxide layer 13 may be formed in the second region II by the same method as that for forming the oxide layer 13 in the first region I. The thickness of the amorphous layer 13 is controlled by controlling the energy and / or dose of ion implantation, so that the thickness ranges of the oxide layer 13 formed in the first region I and the second region II are different.
[0065] The present invention forms an amorphous layer 12 by performing ion implantation on the substrate 10 in the first region I, oxidizes the substrate 10 and the amorphous layer 12 in the first region I to form an oxide layer 13 with a first thickness range, and then performs ion implantation on the substrate 10 in the second region II to form an amorphous layer, and oxidizes the substrate 10 and the amorphous layer in the second region II to form an oxide layer 13 with a second thickness range. The first thickness range of the oxide layer 13 in the first region I is different from the second thickness range of the oxide layer 13 in the second region II, thereby forming oxide layers 13 with different thicknesses in different regions of the substrate 10. Compared with the prior art, the process steps are saved and the manufacturing cost is reduced.
[0066] Figure 6 Schematic diagram of the relationship between the thickness of the oxide layer and the ion implantation dose provided by an embodiment of the present invention. Figure 6 As shown, the horizontal axis is the dose of ion implantation, where the initial position represents no ion implantation, and the vertical axis is the thickness of the oxide layer. Figure 6 It can be seen that as the ion implantation dose increases, the thickness of the oxide layer also increases.
[0067] In summary, in the method for improving the uniformity of a thin film provided by the present invention, a substrate is first provided, wherein a plurality of grooves are formed therein, so that the substrate has a groove portion and a convex portion located between adjacent groove portions; then, ion implantation is performed on the substrate to amorphize at least part of the surface of the convex portion to form an amorphous layer; then, the substrate and the amorphous layer are oxidized to form an oxide layer on the surface of the convex portion. The present invention forms an oxide layer on the surface of the convex portion by amorphization, so that the thickness of the oxide layer is substantially the same or the thickness difference is reduced, thereby improving the thickness difference of the oxide layer at different positions of the groove, improving the thickness difference of the oxide layer at different positions of the substrate, improving the uniformity of the oxide layer thickness, and improving the device performance.
[0068] Furthermore, an amorphous layer is formed by performing ion implantation on the substrate in the first region, the substrate and the amorphous layer in the first region are oxidized to form an oxide layer having a first thickness range, and then an amorphous layer is formed by performing ion implantation on the substrate in the second region, and the substrate and the amorphous layer in the second region are oxidized to form an oxide layer having a second thickness range. The first thickness range of the oxide layer in the first region is different from the second thickness range of the oxide layer in the second region, thereby forming oxide layers with different thicknesses in different regions of the substrate. Compared with the prior art, process steps are saved and manufacturing costs are reduced.
[0069] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.
Claims
1. A method for improving film uniformity, characterized in that: The following steps are involved: Providing a substrate, wherein a plurality of grooves are formed in the substrate, so that the substrate has a groove portion and a convex portion located between adjacent groove portions; Performing ion implantation on the substrate to amorphize at least a portion of the surface of the protrusion to form an amorphous layer; The substrate and the amorphous layer are oxidized to form an oxide layer on the surface of the protrusion.
2. The method for improving thin film uniformity according to claim 1, characterized in that: The thickness of the amorphous layer is controlled by controlling the process conditions of ion implantation, thereby controlling the thickness of the oxide layer.
3. The method for improving thin film uniformity according to claim 2, characterized in that: The thickness of the amorphous layer can be controlled by controlling the energy and / or dose of the ion implantation.
4. The method for improving thin film uniformity according to claim 1, characterized in that: The ions used in the ion implantation include at least one of silicon, germanium, arsenic, tin, gallium, indium, phosphorus, tellurium or bismuth.
5. The method for improving thin film uniformity according to claim 1, characterized in that: The ion implantation angle is -45° to 45°.
6. The method for improving thin film uniformity according to claim 1, characterized in that: The method of oxidizing the substrate includes dry oxygen oxidation, wet oxygen oxidation, plasma oxidation or in-situ water vapor generation process.
7. The method for improving thin film uniformity according to any one of claims 1 to 6, characterized in that: The substrate comprises a first region and a second region, and ion implantation is performed on the substrate in the first region to amorphize the surface of the protrusion in the first region to form an amorphous layer; The substrate and the amorphous layer are oxidized to form an oxide layer, and the oxide layer formed in the first region has a first thickness range.
8. The method for improving thin film uniformity according to claim 7, characterized in that: The method of performing ion implantation on the substrate in the first region includes: forming a photoresist layer, wherein the photoresist layer covers the substrate; exposing and developing the photoresist layer to form a patterned photoresist layer, wherein the patterned photoresist layer covers the second area and exposes the first area; Using the patterned photoresist layer as a mask, ion implantation is performed on the first region.
9. The method for improving thin film uniformity according to claim 7, characterized in that: The method of performing ion implantation on the substrate in the first region includes: forming a hard mask layer, wherein the hard mask layer covers the substrate; Etching the hard mask layer to form a patterned hard mask layer, wherein the patterned hard mask layer covers the second region and exposes the first region; Using the patterned hard mask layer as a mask, ion implantation is performed on the first region.
10. The method for improving thin film uniformity according to claim 7, characterized in that: After forming the oxide layer in the first region, the method further includes: Performing ion implantation on the substrate in the second region to amorphize the surface of the protrusion in the second region to form an amorphous layer; The substrate and the amorphous layer are oxidized to form an oxide layer, the oxide layer formed in the second region has a second thickness range, and the second thickness range of the oxide layer in the second region is different from the first thickness range of the oxide layer in the first region.