A method for detecting the depth of STI trenches

Abstract

This application discloses a method for detecting STI trench depth, comprising: placing photolithography alignment marks in the scribe line region; performing STI etching; collecting photolithography alignment signals; and detecting STI depth by analyzing the photolithography alignment signals. In this method for detecting STI trench depth, the STI depth is determined by collecting and analyzing alignment signals. The alignment marks are used not only for alignment but also to determine STI depth through optical path difference analysis, further enabling analysis of STI depth stability across wafers.

Description

Technical Field

[0001] The present application relates to the field of semiconductor manufacturing technology, and in particular to a method for detecting the depth of an STI trench. Background Art

[0002] In today's IC manufacturing process, a complete chip typically undergoes more than ten to twenty photolithography passes. During these passes, except for the first, each subsequent layer of photolithography must be aligned with the pattern left behind on the previous layer before exposure. This alignment process occurs during the plate loading and wafer exposure process, ensuring that the pattern on the photolithography plate is overlaid with the existing pattern on the wafer with maximum precision.

[0003] Alignment accuracy is one of the most important performance indicators in photolithography. A photolithography machine must achieve alignment by optically identifying alignment marks on the silicon wafer. Typically, alignment marks for a layer are created simultaneously with the current process and used for alignment during the next layer's photolithography. Alignment marks are typically a set of horizontal and vertical stripes of varying widths and numbers. To ensure optical recognition, these marks are typically at least 1 micron wide and several tens of microns long.

[0004] Shallow trench isolation (STI) is widely used in various semiconductor devices. The depth of the shallow trench has a significant impact on the electrical parameters of the device. Currently, the depth of STI is mainly detected by atomic force microscopy (AFM). However, the process of using AFM to detect STI is slow and the program editing is complex. Summary of the Invention

[0005] The present application provides a method for detecting the depth of an STI trench, so as to solve the problem that the current process of detecting the depth of an STI by an atomic force microscope is slow and the program editing is complicated.

[0006] An embodiment of the present application provides a method for detecting STI trench depth, including:

[0007] Step 1: Place photolithography alignment marks in the scribe line area;

[0008] Step 2: Perform STI etching;

[0009] Step 3: Collecting photolithography alignment signals;

[0010] Step 4: Detect the STI depth by analyzing the photolithography alignment signal.

[0011] Furthermore, the alignment signal value and the STI depth vary linearly.

[0012] Furthermore, the stability of the STI depth between different wafers is determined by monitoring the alignment signal value.

[0013] Furthermore, the STI etching is performed, and an alignment process in the STI etching process is performed using the alignment mark as an alignment condition.

[0014] Furthermore, the alignment mark is a zero-layer alignment mark.

[0015] Furthermore, the alignment mark includes a plurality of mark patterns.

[0016] Furthermore, the formation area of the alignment mark is in a strip shape.

[0017] Furthermore, each of the mark patterns is arranged in the alignment mark formation region and constitutes the alignment mark.

[0018] Furthermore, each of the marking graphics is in a bar shape.

[0019] The technical solution of this application has at least the following advantages:

[0020] In an embodiment of the present application, in the method for detecting the STI groove depth, the STI depth is determined by collecting and analyzing the alignment signal. The alignment mark can not only be used for alignment, but also the STI depth can be obtained through optical path difference analysis, and the stability of the STI depth between different wafers can be further analyzed. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. 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 any creative work.

[0022] Figure 1 This is a schematic flow chart of the steps of a method for detecting STI trench depth provided by an exemplary embodiment of the present application;

[0023] Figure 2 This is a diagram showing the relationship between the lithography signal and the STI depth provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The following is a clear and complete description of the technical solutions in this application in conjunction with the accompanying drawings. Obviously, the embodiments described 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 making any creative efforts are within the scope of protection of this application.

[0025] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this application and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal connections between two components; they can refer to wireless connections or wired connections. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0027] 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.

[0028] Figure 1 FIG. 1 is a flow chart of the steps of a method for detecting the depth of an STI trench provided by an exemplary embodiment of the present application. Figure 1 , a method for detecting STI trench depth, comprising:

[0029] S11, placing a photolithography alignment mark in the scribe line area;

[0030] S12, performing STI etching;

[0031] S13, collecting lithography alignment signals;

[0032] S14 , detecting the STI depth by analyzing the photolithography alignment signal.

[0033] To more intuitively reveal the technical features of the present invention and highlight its beneficial effects, the working principle of the method for detecting STI trench depth of the present invention is now explained in conjunction with a specific embodiment. In the specific embodiment, the formation process, method, structural characteristics, dimensions, etc. of each functional layer described are merely examples and should not be construed as limiting the technical solution of the present invention. Conventional processes, methods, materials, etc. in the field are not further described.

[0034] The alignment mark is applicable to the depth structure of various film layers and is not limited to silicon substrates. In an embodiment of the present invention, a plurality of scribe grooves are provided on the semiconductor substrate, and each scribe groove divides the semiconductor substrate into a plurality of areas to be fabricated.

[0035] In an embodiment of the present invention, the alignment process in the STI etching process uses the alignment mark as an alignment condition for alignment. The alignment mark is a zero-layer alignment mark. The alignment mark includes multiple mark patterns, each of which is arranged in the alignment mark formation area and constitutes the alignment mark, and each of the mark patterns is in a bar shape. When the lithography machine uses the lithography alignment marks for alignment, the feedback signal from the machine can quickly detect the depth of the STI trench.

[0036] Table 1 shows the corresponding relationship between STI depth and lithography signal provided by an embodiment of the present invention.

[0037] Table 1

[0038]

[0039]

[0040] By analyzing the STI depths measured in Table 1 and the lithography signal values, we find that there is a linear relationship between the STI depth and the lithography signal.

[0041] Figure 2 The relationship between the lithography signal and the STI depth provided by the embodiment of the present invention is shown in FIG. Figure 2 In the graph showing the relationship between the lithography signal and STI depth, the x-axis represents the STI depth, and the y-axis represents the lithography signal value. The linear relationship between the two is y = 0.0178x - 55.109. Therefore, the STI depth can be determined by simply using the alignment information obtained after lithography alignment. The stability of STI depth between wafers can also be determined by monitoring the alignment signal value. Obtaining STI depth values during lithography is simpler than traditional methods using atomic force microscopy to detect STI depth, and it saves process steps.

[0042] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of this application.

Claims

1. A method for detecting STI trench depth, characterized in that: include: Placing photolithography alignment marks in the scribe line area; Perform STI etching; Collecting photolithography alignment signals; Detecting the STI depth by analyzing the photolithography alignment signal; The alignment signal value varies linearly with the STI depth.

2. The method for detecting STI trench depth according to claim 1, wherein: The stability of the STI depth between different wafers is determined by monitoring the alignment signal value.

3. The method for detecting STI trench depth according to claim 1, wherein: The STI etching is performed, and an alignment process in the STI etching process is performed using the alignment mark as an alignment condition.

4. The method for detecting STI trench depth according to claim 1, wherein: The alignment mark is a zero-layer alignment mark.

5. The method for detecting STI trench depth according to claim 1, wherein: The alignment mark includes a plurality of mark patterns.

6. The method for detecting STI trench depth according to claim 5, wherein: The formation area of the alignment mark is in a stripe shape.

7. The method for detecting STI trench depth according to claim 6, wherein: The mark patterns are arranged in the alignment mark formation region and constitute the alignment mark.

8. The method for detecting STI trench depth according to claim 7, wherein: Each of the marking graphics is in a bar shape.

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