Method for detecting shallow trench isolation structure hole
By overetching the silicon nitride removal node of the shallow trench isolation structure, the holes are exposed and detected by electron beam scanning, the hole problems that cannot be discovered by traditional detection methods are solved and the product yield is improved.
Patent Information
- Application Number
- CN202510039823.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-09
- Publication Date
- 2025-05-06
AI Technical Summary
In shallow trench isolation (STI) processes, there may be holes that cannot be detected by traditional detection methods. These holes will form defects in the subsequent process with high-killing properties, resulting in yield loss.
The shallow trench isolation structure is overetched at the silicon nitride removal node to expose potential holes, and then hole detection is performed using electron beam scanning and other methods.
Effectively detect holes in shallow trench isolation structures, facilitate timely processing and improve product yield.
Smart Images
Figure CN119943695A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of semiconductor manufacturing, and in particular to a method for detecting holes in a shallow trench isolation structure. Background Art
[0002] Shallow Trench Isolation (STI) has the advantages of good isolation effect and small occupied area. Therefore, although its process is more complicated than the traditional local oxidation of silicon (LOCOS) isolation method, the STI method is still widely used for isolation between devices in processes below 0.25um.
[0003] At present, the process flow of making STI includes: silicon oxide and silicon nitride deposition on silicon substrate, STI trench etching, STI field oxide growth, chemical mechanical polishing of field oxide, wet etching of STI and removal of silicon nitride. In the above process, holes may appear in STI, which will not be exposed on the surface of wafer and cannot be detected by SEM electron beam scanning detection, bright field detection and dark field detection. In the subsequent process, the above holes will form defects with high yield-killing characteristics, resulting in a large amount of yield loss. Summary of the invention
[0004] In order to solve the above problems, the present application provides a method for detecting holes in a shallow trench isolation structure.
[0005] The present application provides a method for detecting holes in a shallow trench isolation structure, comprising: S1: providing a wafer to be subjected to a silicon nitride removal process, wherein a shallow trench isolation structure is formed in a substrate of the wafer, and a silicon oxide layer and a silicon nitride layer are sequentially formed on a surface of the substrate, wherein a top of the silicon nitride layer is higher than a top of the shallow trench isolation structure; S2: removing the silicon nitride layer; S3: over-etching the top of the shallow trench isolation structure so that the top of the remaining shallow trench isolation is lower than the top of the silicon oxide layer; S4: performing hole detection on the shallow trench isolation structure.
[0006] In some embodiments, in S3, the top of the shallow trench isolation structure is over-etched by a wet etching process.
[0007] In some embodiments, the etching depth of the shallow trench isolation structure is 180-220 angstroms.
[0008] In some embodiments, in S4, the wafer is subjected to electron beam scanning by an EBI machine to perform hole detection on the shallow trench isolation structure.
[0009] In some embodiments, in S2, the silicon nitride layer is removed by a wet etching process.
[0010] The technical solution of this application has at least the following advantages: 1. By removing nodes in silicon nitride and over-etching the shallow trench isolation structure, possible holes in the shallow trench isolation structure are exposed, and then the trench isolation structure is inspected for holes, which can effectively detect shallow trench isolation holes, facilitate timely processing, and improve product yield. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0012] Figure 1 is a flow chart of a method for detecting holes in a shallow trench isolation structure provided by an exemplary embodiment of the present application; Figure 2~Figure 4 is a schematic diagram of a device during the execution of a method for detecting holes in a shallow trench isolation structure provided by an exemplary embodiment of the present application; Figure 5 It is a schematic diagram of a shallow trench isolation structure hole exposed after step S3 provided by an exemplary embodiment of the present application.
[0013] Explanation of the reference numerals: 1. substrate; 2. shallow trench isolation structure; 21. field oxide layer; 3. silicon oxide layer; 4. silicon nitride layer. DETAILED DESCRIPTION
[0014] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0015] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and 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 limiting the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.
[0016] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "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 a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.
[0017] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.
[0018] The present application provides a method for detecting holes in a shallow trench isolation structure, referring to Figure 1 , the method comprises the following steps: S1: providing a wafer to be subjected to a silicon nitride removal process, wherein a shallow trench isolation structure is formed in a substrate of the wafer, and a silicon oxide layer and a silicon nitride layer are sequentially formed on a surface of the substrate, wherein a top of the silicon nitride layer is higher than a top of the shallow trench isolation structure.
[0019] Exemplarily, a wafer is provided, which has undergone a process of pre-deposition of silicon oxide and silicon nitride, STI trench etching, STI HARP (High Aspect Ratio Process) field oxide growth, chemical mechanical polishing of HARP field oxide, and STI wet etching, and then transferred to a silicon nitride removal station. Figure 2 The wafer includes a substrate, such as a silicon substrate, in which a shallow trench isolation structure is formed, and the shallow trench isolation structure includes a trench and a field oxide layer filled in the trench. A silicon oxide layer is formed on the surface of the substrate and between the substrate and the field oxide layer, and a silicon nitride layer is formed on the silicon oxide layer on the surface of the substrate, and the top of the silicon nitride layer is higher than the top of the shallow trench isolation structure.
[0020] S2: removing the silicon nitride layer.
[0021] Exemplarily, the silicon nitride layer is removed, and after the removal, the device is as follows Figure 3 shown.
[0022] Furthermore, a wet etching process may be used to remove the oxide layer.
[0023] S3: over-etching the top of the shallow trench isolation structure so that the top of the remaining shallow trench isolation is lower than the top of the silicon oxide layer.
[0024] For example, refer to Figure 4 , the top of the shallow trench isolation structure, that is, the top of the field oxide layer, is over-etched so that the top of the remaining shallow trench isolation is lower than the top of the silicon oxide layer. In this process, if there are holes in the shallow trench isolation structure, such as Figures 2 to 4 As shown in , the hole will be exposed as the height of the shallow trench isolation structure decreases, as shown in Figure 4 and Figure 5 shown.
[0025] Furthermore, a wet etching process may be used to over-etch the top of the shallow trench isolation structure.
[0026] Furthermore, the etching depth of the shallow trench isolation structure may be 180-220 angstroms. In other embodiments, the etching depth may be specifically adjusted to ensure that potential holes can be exposed.
[0027] S4: Perform hole detection on the shallow trench isolation structure.
[0028] For example, an EBI machine may be used to perform electron beam scanning on a wafer that has undergone S3 processing to detect whether there are holes in the shallow trench isolation structure that has undergone over-etching processing.
[0029] The method for detecting holes in a shallow trench isolation structure provided in an embodiment of the present application can effectively detect shallow trench isolation holes by over-etching the shallow trench isolation structure after the silicon nitride removal process to expose holes that may exist in the shallow trench isolation structure, and then performing hole detection on the trench isolation structure, thereby facilitating timely processing and improving product yield.
[0030] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection created by this application.
Claims
1. A method for detecting holes in a shallow trench isolation structure, characterized in that: include: S1: providing a wafer to be subjected to a silicon nitride removal process, wherein a shallow trench isolation structure is formed in a substrate of the wafer, and a silicon oxide layer and a silicon nitride layer are sequentially formed on a surface of the substrate, wherein a top of the silicon nitride layer is higher than a top of the shallow trench isolation structure; S2: removing the silicon nitride layer; S3: over-etching the top of the shallow trench isolation structure so that the top of the remaining shallow trench isolation is lower than the top of the silicon oxide layer; S4: performing hole detection on the shallow trench isolation structure.
2. The method for detecting holes in shallow trench isolation structures according to claim 1, characterized in that: In S3, the top of the shallow trench isolation structure is over-etched by a wet etching process.
3. The method for detecting holes in shallow trench isolation structures according to claim 2, characterized in that: The etching depth of the shallow trench isolation structure is 180-220 angstroms.
4. The method for detecting holes in shallow trench isolation structures according to claim 1, characterized in that: In S4, the wafer is subjected to electron beam scanning by an EBI machine to perform hole detection on the shallow trench isolation structure.
5. The method for detecting holes in shallow trench isolation structures according to claim 1, characterized in that: In S2, the silicon nitride layer is removed by a wet etching process.