Method for improving back sealing defect of substrate
By forming a stacked high-temperature oxide film layer and polysilicon layer on the back of the substrate, and using wet etching treatment, the problem of arc defects on the back of the substrate is solved, and the stability of the back of the seal and the growth quality of the epitaxial layer are improved.
Patent Information
- Application Number
- CN202510293373.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-12
- Publication Date
- 2025-07-11
AI Technical Summary
In the prior art, a silicon epitaxial process is implemented on the front of the substrate to form arc defects on the back seal layer of the substrate, resulting in a degradation of the back seal performance.
By forming a laminated structure of the first high-temperature oxide film layer, a polysilicon layer and a second high-temperature oxide film layer on the back of the substrate, and removing unnecessary film layers by wet etching to ensure that the edges are neat, forming a neat structure of the first low-temperature oxide film layer, a polysilicon layer and a second low-temperature oxide film layer.
It effectively avoids the fall of silicon on the polysilicon layer, prevents the formation of arc defects, ensures the stable growth of the subsequent epitaxial layer, and improves the performance of the substrate back seal layer.
Smart Images
Figure CN120299982A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor technology, and particularly to a method for improving substrate backseal defects. Background Art
[0002] When fabricating semiconductor device products using a heavily doped substrate, in order to prevent dopants from escaping from the back of the substrate during the high-temperature processes of subsequent product wafer processing, which may affect the process chamber atmosphere and the doping concentration of the front-side film layer of the substrate, an oxide film layer is usually formed on the back of the substrate for backsealing. To prevent the oxide film layer serving as the substrate backseal layer from being removed by the wet etching process in the subsequent wafer processing, a polysilicon layer is formed on the oxide film layer, or a polysilicon layer and another oxide film layer are formed sequentially.
[0003] When performing a silicon epitaxial process on the front side of the substrate, the silicon that falls off in the high-temperature furnace tube forms arc-shaped defects in the exposed part of the polysilicon layer in the substrate backseal layer under the state of nitrogen flushing and wafer boat rotation, resulting in a decline in the backsealing performance of the substrate backseal layer. Summary of the Invention
[0004] In view of the above-mentioned disadvantages of the prior art, the purpose of this application is to provide a method for improving substrate backseal defects, which is used to solve the problem of forming arc-shaped defects on the substrate backseal layer during the silicon epitaxial process on the front side of the substrate in the prior art.
[0005] To achieve the above purpose and other related purposes, this application provides a method for improving substrate backseal defects, including:
[0006] Step 1: Provide a substrate and form a first high-temperature oxide film layer covering the substrate;
[0007] Step 2: Form a polysilicon layer covering the first high-temperature oxide film layer;
[0008] Step 3: Form a second high-temperature oxide film layer covering the polysilicon layer;
[0009] Step 4: Remove the second high-temperature oxide film layer and the polysilicon layer located in the front and edge regions of the substrate;
[0010] Step 5: After performing a cleaning process, remove the first high-temperature oxide film layer located in the front and edge regions of the substrate.
[0011] Preferably, the first high-temperature oxide film layer and the second high-temperature oxide film layer are formed by a high-temperature oxidation process.
[0012] Preferably, the polysilicon layer is formed by a low-pressure chemical vapor deposition process.
[0013] Preferably, the gas source for low-pressure chemical vapor deposition is silane, and the temperature is 600°C - 700°C.
[0014] Preferably, the second high-temperature oxide film layer, the polysilicon layer, and the first high-temperature oxide film layer have different thicknesses.
[0015] Preferably, the second high-temperature oxide film layer and the polysilicon layer located on the front and edge regions of the substrate are removed by a first wet etching process.
[0016] Preferably, when performing the first wet etching, the second high-temperature oxide film layer on the front and edge regions of the substrate is first removed by hydrofluoric acid, and then the polysilicon layer on the front and edge regions of the substrate is removed by a mixed solution of hydrofluoric acid and nitric acid.
[0017] Preferably, the first high-temperature oxide film layer located on the front and edge regions of the substrate is removed by a second wet etching process.
[0018] Preferably, the etching solution for the second wet etching is a BOE buffered etching solution or an aqueous solution of hydrogen fluoride.
[0019] Preferably, after the end of step five, the formed substrate back-sealing layer is composed of a first low-temperature oxide film layer, a polysilicon layer, and a second low-temperature oxide film layer stacked in sequence, and the edges of the first low-temperature oxide film layer, the polysilicon layer, and the second low-temperature oxide film layer are neat.
[0020] As described above, the method for improving the substrate back-sealing defect provided by the present application has the following beneficial effects: the formed substrate back-sealing layer is composed of a stacked first low-temperature oxide film layer, a polysilicon layer, and a second low-temperature oxide film layer, and the edges of the first low-temperature oxide film layer, the polysilicon layer, and the second low-temperature oxide film layer are neat, making the crystal orientation of the side surface of the polysilicon layer relatively simple. When an epitaxial layer is formed on the substrate subsequently, it is not easy to grow silicon on the polysilicon layer, and the grown silicon is not easy to fall off, avoiding the formation of arc-shaped defects. Description of the Drawings
[0021] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0022] Figure 1A Shown is a flowchart of forming a substrate back-sealing layer in the prior art;
[0023] Figure 1B Shown is a schematic cross-sectional structure diagram of a substrate after forming a substrate back-sealing layer according to the prior art;
[0024] Figure 1CAn electron micrograph showing the arc-shaped defects formed on the back-sealing layer of the substrate by implementing the silicon epitaxial process on the front side of the substrate;
[0025] Figure 2 A flowchart showing the method for improving the back-sealing defects of the substrate provided by the embodiment of the present application;
[0026] Figures 3A - 3E A schematic cross-sectional structure diagram of the substrate formed after each step in the method for improving the back-sealing defects of the substrate provided by the embodiment of the present application. Detailed implementation manners
[0027] The following illustrates the implementation manners of the present application through specific specific examples. Those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. The present application can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0028] Next, the technical solutions in the present application will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.
[0029] In the description of the present application, it should be noted that the orientation or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.
[0030] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can also be the communication inside two elements. It can be a wireless connection or a wired connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.
[0031] In addition, the technical features involved in different implementation manners of the present application described below can be combined with each other as long as they do not conflict with each other.
[0032] As shown Figure 1A in the figure, the steps of forming the substrate back-sealing layer in the prior art include:
[0033] First, after depositing a first low-temperature oxide film layer on the back of the substrate, the first low-temperature oxide film layer located in the edge region of the substrate is removed;
[0034] Next, a polysilicon layer covering the substrate and the first low-temperature oxide film layer is formed;
[0035] Next, a second low-temperature oxide film layer is deposited on the back of the substrate;
[0036] Next, the second low-temperature oxide film layer located in the edge region of the substrate is removed;
[0037] Finally, the polysilicon layer located on the front and edge regions of the substrate is removed by the edge grinding process.
[0038] As shown Figure 1B in the figure, the formed substrate back-sealing layer is composed of a stacked first low-temperature oxide film layer, a polysilicon layer, and a second low-temperature oxide film layer. The non-alignment of the edges of the first low-temperature oxide film layer, the polysilicon layer, and the second low-temperature oxide film layer results in the exposure of the polysilicon layer, and a stepped edge structure is prone to form an arc defect as shown Figure 1C in the figure.
[0039] To solve this problem, the present application provides a method for improving the substrate back-sealing defect.
[0040] Please refer to Figure 2 , which shows a flowchart of the method for improving the substrate back-sealing defect provided by the embodiment of the present application.
[0041] As shown Figure 2 in the figure, the method for improving the substrate back-sealing defect includes the following steps:
[0042] Step 1: Provide a substrate and form a first high-temperature oxide film layer covering the substrate;
[0043] Step 2: Form a polysilicon layer to cover the first high-temperature oxide film layer;
[0044] Step 3: Form a second high-temperature oxide film layer to cover the polysilicon layer;
[0045] Step 4: Remove the second high-temperature oxide film layer and the polysilicon layer located on the front and edge regions of the substrate;
[0046] Step 5: After performing a cleaning process, remove the first high-temperature oxide film layer located on the front and edge regions of the substrate.
[0047] In Step 1, as shown Figure 3AAs shown, optionally, the substrate 300 is a silicon substrate. As an example, a first high-temperature oxide film layer 301 is formed by a high-temperature oxidation process.
[0048] In step two, as Figure 3B shown, as an example, a polysilicon layer 302 is formed by a low-pressure chemical vapor deposition process. The gas source for the low-pressure chemical vapor deposition is silane, and the temperature is 600°C - 700°C.
[0049] In step three, as Figure 3C shown, a second high-temperature oxide film layer 303 is formed by a high-temperature oxidation process. As an example, the second high-temperature oxide film layer 303, the polysilicon layer 302, and the first high-temperature oxide film layer 301 may have different thicknesses.
[0050] In step four, as Figure 3D shown, the second high-temperature oxide film layer 303 and the polysilicon layer 302 located on the front and edge regions of the substrate 300 are removed by a first wet etching process. The edge region of the substrate 300 includes the side portion of the substrate 300 and the region near the side portion. As an example, when implementing the first wet etching, first, the second high-temperature oxide film layer 303 on the front and edge regions of the substrate 300 is removed using hydrofluoric acid, and then the polysilicon layer 302 on the front and edge regions of the substrate 300 is removed using a mixed solution of hydrofluoric acid and nitric acid.
[0051] In step five, the cleaning treatment is implemented by immersing or rinsing with deionized water.
[0052] As Figure 3E shown, the first high-temperature oxide film layer 301 located on the front and edge regions of the substrate 300 is removed by a second wet etching process. As an example, the etching solution for the second wet etching is a BOE buffer etching solution (an aqueous solution of hydrogen fluoride and ammonium fluoride) or an aqueous solution of hydrogen fluoride.
[0053] After step five, the formed substrate back-sealing layer is composed of a first low-temperature oxide film layer 301, a polysilicon layer 302, and a second low-temperature oxide film layer 303 stacked in sequence. The edges of the first low-temperature oxide film layer 301, the polysilicon layer 302, and the second low-temperature oxide film layer 303 are neat, making the crystal orientation of the side surface of the polysilicon layer 302 relatively simple. When an epitaxial layer is formed on the substrate 300 later, it is not easy to grow silicon on the polysilicon layer 302, and the grown silicon is not easy to fall off, avoiding the formation of arc-shaped defects as Figure 1C shown. Therefore, the present application effectively overcomes various disadvantages in the prior art and has high industrial utilization value.
[0054] It should be noted that the illustrations provided in this embodiment only schematically illustrate the basic concept of the present application. Therefore, only the components related to the present invention are shown in the drawings, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and proportion of each component in actual implementation may be arbitrarily changed, and the component layout type may also be more complex.
[0055] The above embodiments are only illustrative of the principles and effects of the present application, rather than limiting the present application. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present application.
Claims
1. A method for improving substrate backseal defects, characterized in that, The method includes: Step 1: Provide a substrate and form a first high-temperature oxide film layer coating the substrate; Step 2: Form a polysilicon layer coating the first high-temperature oxide film layer; Step 3: Form a second high-temperature oxide film layer coating the polysilicon layer; Step 4: Remove the second high-temperature oxide film layer and the polysilicon layer located on the front and edge regions of the substrate; Step 5: After performing a cleaning process, remove the first high-temperature oxide film layer located on the front and edge regions of the substrate.
2. The method according to claim 1, wherein The first high-temperature oxide film layer and the second high-temperature oxide film layer are formed by a high-temperature oxidation process.
3. The method according to claim 1, characterized in that The polysilicon layer is formed by a low-pressure chemical vapor deposition process.
4. The method according to claim 3, wherein The gas source for the low-pressure chemical vapor deposition is silane, and the temperature is 600°C - 700°C.
5. The method according to claim 1, characterized in that, The second high-temperature oxide film layer, the polysilicon layer, and the first high-temperature oxide film layer have different thicknesses.
6. The method according to claim 1, wherein The second high-temperature oxide film layer and the polysilicon layer located on the front and edge regions of the substrate are removed by a first wet etching process.
7. The method according to claim 6, characterized in that, When performing the first wet etching, first use hydrofluoric acid to remove the second high-temperature oxide film layer on the front and edge regions of the substrate, and then use a mixed solution of hydrofluoric acid and nitric acid to remove the polysilicon layer on the front and edge regions of the substrate.
8. The method according to claim 1, wherein The first high-temperature oxide film layer located on the front and edge regions of the substrate is removed by a second wet etching process.
9. The method according to claim 8, wherein The etching solution for the second wet etching is a BOE buffer etching solution or an aqueous hydrogen fluoride solution.
10. The method according to claim 1, wherein After the end of Step 5, the formed substrate back-sealing layer is composed of the first low-temperature oxide film layer, the polysilicon layer, and the second low-temperature oxide film layer stacked in sequence, and the edges of the first low-temperature oxide film layer, the polysilicon layer, and the second low-temperature oxide film layer are neat.