Hole detection method and detection device

Abstract

The invention provides a cavity detection method and device, and the method comprises the steps: collecting a spectral signal of a groove region of a to-be-detected wafer, and obtaining an optical parameter of a filling region of the to-be-detected wafer, and according to the optical parameters and the calibration curve, judging whether a cavity exists in the filling area of the wafer to be detected, and obtaining the size or the void rate of the cavity. According to the cavity detection method provided by the invention, whether the cavity exists in the filling area of the to-be-detected wafer can be quickly judged by comparing the optical parameters of the to-be-detected wafer with the calibration curve, and meanwhile, the cavity size or the cavity rate can be obtained according to the calibration curve, so that the cavity detection speed is greatly improved, the detection time is saved, and the detection efficiency is improved. And destructive detection of the to-be-detected wafer is not needed.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a void detection method and a detection device. Background Art

[0002] With the continuous development of integrated circuit technology, the integration of chips is getting higher and higher. In order to avoid mutual influence between devices, STI (shallow trench isolation) is needed to isolate the devices in integrated circuits. As the process node decreases, the depth-to-width ratio of the isolation trench increases, the requirements for isolation trench filling are getting higher and higher, and the filling of isolation trenches is becoming more and more difficult.

[0003] At present, the industry generally adopts High Aspect Ratio Process (HARP) for filling isolation trenches. It has strong filling ability and can well fill isolation trenches with large aspect ratios. However, as the feature size becomes smaller and smaller, the aspect ratio of the isolation trench continues to increase. When the HARP process is used to fill the isolation trench, it is easy to form voids in the isolation trenches. The voids will seriously affect the electrical performance of the device. Therefore, the detection of voids is particularly important.

[0004] Existing void detection methods generally include scanning electron microscopy (SEM) detection and transmission electron microscopy (TEM) detection. SEM detection takes a long time to scan and can only monitor surface voids, while TEM detection requires slicing, which is complex and highly destructive. Therefore, it is necessary to provide a void detection method that has a fast measurement speed and is non-destructive. Summary of the invention

[0005] The object of the present invention is to provide a void detection method, which can reduce the time of void detection, increase the speed of void detection, and realize non-destructive detection of voids inside isolation grooves.

[0006] In order to solve the above technical problems, the present invention provides a cavity detection method, comprising the following steps:

[0007] Collecting spectral signals of the filling area of ​​the wafer to be inspected to obtain optical parameters of the filling area of ​​the wafer to be inspected; and

[0008] It is determined whether there is a void in the filling area of ​​the wafer to be inspected according to the optical parameters and the calibration curve, and the size or void ratio of the void is obtained.

[0009] Optionally, the method of drawing a calibration curve includes:

[0010] collecting spectral signals of a plurality of filling areas of a sample wafer;

[0011] Obtaining optical parameters of the filling area of ​​the sample wafer by spectral fitting;

[0012] measuring void sizes or void ratios within a plurality of filling regions of the sample wafer; and,

[0013] The calibration curve is drawn according to the void size or void ratio and the corresponding optical parameters.

[0014] Optionally, the optical parameter includes a refractive index of the filling area or a phase difference in a spectral signal.

[0015] Optionally, the film layer filled in the filling area includes a metal layer, an oxide layer, a nitride layer, an amorphous silicon layer, a polysilicon layer, a photoresist layer, a low-K material layer, a silicon oxynitride layer, a silicon carbide nitride layer, an anti-reflective layer or a multi-layer film reflective polarizer.

[0016] Optionally, the filling region includes a trench region, and the trench region includes a substrate, an isolation trench formed in the substrate, and an insulating material filled in the isolation trench.

[0017] Optionally, the cavity is formed in the isolation trench.

[0018] Optionally, in collecting spectral signals of multiple filling areas of a sample wafer, the filling areas are multiple filling areas of the same sample wafer, or / and, the filling area is one filling area of ​​multiple sample wafers.

[0019] Optionally, the method for measuring the void size or void ratio in multiple filling areas of the sample wafer includes: slicing the sample wafer in a direction perpendicular to the sample wafer to expose the voids in the filling areas, and measuring the size or void ratio of the exposed voids using a transmission electron microscope.

[0020] Optionally, after obtaining the optical parameter or the size of the void or the void ratio, the method further includes: obtaining a dielectric constant of a filling area of ​​the wafer to be inspected.

[0021] Accordingly, the present invention also provides a cavity detection device, comprising:

[0022] A light source, wherein the linearly polarized light provided by the light source is incident on the surface of the filling area of ​​the wafer to be inspected at a non-perpendicular angle;

[0023] a spectrometer, the spectrometer receiving reflected light and refracted light from the surface of the filling area of ​​the wafer to be inspected to obtain a spectral signal; and

[0024] A processing system is provided, wherein the processing system obtains optical parameters of the filling area of ​​the wafer to be inspected according to the spectral signal, and determines whether there are voids in the filling area of ​​the wafer to be inspected according to the optical parameters and a calibration curve, and obtains the size or void ratio of the voids.

[0025] Compared with the prior art, in the void detection method and detection device provided by the present invention, the spectral signal of the filling area of ​​the wafer to be detected is first collected to obtain the optical parameters of the filling area of ​​the wafer to be detected, and the presence of voids in the filling area of ​​the wafer to be detected and the size or void ratio of the voids are determined based on the optical parameters and the calibration curve. The void detection method provided by the present invention can quickly determine whether there are voids in the filling area of ​​the wafer to be detected by comparing the optical parameters of the filling area of ​​the wafer to be detected with the calibration curve, and can also obtain the void size or void ratio based on the calibration curve, which greatly improves the void detection speed, saves detection time, and does not require destructive detection of the wafer to be detected. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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.

[0027] Figure 1 It is a flow chart of a hole detection method provided by an embodiment of the present invention.

[0028] Figure 2 It is a schematic diagram of the principle of the ellipsometry method provided by one embodiment of the present invention.

[0029] Figure 3 It is a schematic diagram of spectrum acquisition provided by an embodiment of the present invention.

[0030] Figure 4a It is a schematic structural diagram of a groove region not including a void provided by an embodiment of the present invention.

[0031] Figure 4b It is a schematic structural diagram of a groove region including a cavity provided by an embodiment of the present invention.

[0032] Figure 5 is a schematic diagram of a calibration curve provided by an embodiment of the present invention.

[0033] Figure 6 is a schematic diagram of a calibration curve provided by another embodiment of the present invention.

[0034] Figure 7 Schematic diagram of the relationship between dielectric constant and void ratio provided by one embodiment of the present invention.

[0035] In the attached figure:

[0036] 10-wafer to be inspected; 11-substrate; 12-isolation trench; 13-insulating material; 14-void. 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 FIG. 1 is a flow chart of a hole detection method provided by an embodiment of the present invention. Figure 1 As shown, the hole detection method provided by the embodiment of the present invention includes the following steps:

[0040] Step S1: collecting spectral signals of the filling area of ​​the wafer to be inspected to obtain optical parameters of the filling area of ​​the wafer to be inspected;

[0041] Step S2: judging whether there are voids in the filling area of ​​the wafer to be inspected according to the optical parameters and the calibration curve, and obtaining the size or void ratio of the voids.

[0042] In step S1, a spectral signal of a filling area of ​​a wafer to be inspected is collected, and optical parameters of the filling area of ​​the wafer to be inspected are obtained by spectral fitting.

[0043] Firstly, the position of the filling area of ​​the wafer to be inspected is determined. Then, the spectrum signal of the filling area of ​​the wafer to be inspected is collected.

[0044] In this embodiment, ellipsometry (SE) is used to collect spectral signals and perform subsequent spectral fitting. When polarized light waves pass through a medium, they interact with the medium. This interaction changes the polarization state of the light waves. By testing the change in the polarization state and then performing analysis and fitting, relevant information about the medium can be obtained. Figure 2 is a schematic diagram of the ellipsometry method provided by an embodiment of the present invention, please refer to Figure 2 As shown, when a beam of linear polarized light is incident on the surface of the object to be measured at a non-vertical angle, for example, when the incident angle is an acute angle θ, the reflected light in the S direction and the refracted light in the P direction reach the maximum. The delay caused by the refractive index N of the object to be measured and the additional distance cause the P polarized light to produce a phase shift difference △ relative to the S polarized light. The recombined polarized light is elliptically polarized light. The refractive index N of the object to be measured can be obtained through the phase difference in the collected spectral information.

[0045] Figure 3 is a schematic diagram of spectrum collection provided by an embodiment of the present invention. Figure 2 As shown, the linearly polarized light provided by the light source is incident on the surface of the wafer 10 to be inspected at an acute angle θ, and is reflected and refracted on the surface of the wafer 10 to be inspected. A spectrometer is used to receive the reflected light and the refracted light, thereby obtaining a spectral signal.

[0046] Next, optical parameters of the filling area of ​​the wafer to be inspected are obtained by spectrum fitting.

[0047] In one embodiment of the present invention, the optical parameter may be the refractive index of the filling area. Specifically, the phase difference in the spectral information is collected, and the refractive index of the filling area is obtained according to the phase difference. In another embodiment of the present invention, the optical parameter may be the phase difference, that is, the phase difference generated by P-polarized light relative to S-polarized light. Since the phase difference is proportional to the refractive index, in this embodiment, it is only necessary to obtain the phase difference of the filling area of ​​the wafer to be inspected, and there is no need to calculate the refractive index through the phase difference. Of course, in other embodiments of the present invention, the optical parameter may also be other parameters known to those skilled in the art that have a corresponding relationship with the refractive index.

[0048] In this embodiment, the film layer filled in the filling area includes a light-transmitting film layer, such as a metal layer (such as a metal layer below 600 angstroms), an oxide layer, a nitride layer, an amorphous silicon layer, a polysilicon layer, a photoresist layer, a low-K material layer, a silicon oxynitride layer, a silicon carbide nitride layer, an anti-reflective layer or a multi-layer film reflective polarizer (APF). Of course, it is not limited to this.

[0049] In one embodiment of the present invention, the filling region may be a groove region. Figure 4ais a schematic structural diagram of a groove region not including a void provided by an embodiment of the present invention, Figure 4b is a schematic diagram of a structure of a trench region including a cavity provided by an embodiment of the present invention. Figure 4a and Figure 4b As shown, the groove region of the wafer 10 to be inspected includes a substrate 11 and an isolation groove 12 formed in the substrate 11 . The isolation groove 12 is filled with an insulating material 13 . Exemplarily, the insulating material 13 is silicon oxide. Figure 4b The isolation trench 12 is shown with a cavity 14 formed therein.

[0050] In step S2, it is determined whether there are voids in the filling area of ​​the wafer to be inspected according to the optical parameters and the calibration curve, and the size or void ratio of the voids is obtained.

[0051] Among them, the size can be understood as the area of ​​the void, the equivalent volume or the equivalent size (such as diameter, etc.); the void ratio can be understood as the ratio of the area of ​​the void to the area of ​​the entire filling area, the area of ​​the void refers to the area of ​​the void obtained after slicing, and the area of ​​the filling area refers to the area of ​​the filling area obtained after slicing.

[0052] In this embodiment, the method for drawing a calibration curve includes: providing a sample wafer, wherein a plurality of filling regions are formed in the sample wafer, some of the filling regions contain voids, and the voids in different filling regions have different sizes, and some of the filling regions do not contain voids.

[0053] Exemplarily, multiple filling regions of the same sample wafer may be collected, or one filling region of multiple sample wafers may be collected. Of course, multiple filling regions of multiple sample wafers may also be collected, which is not limited in this embodiment.

[0054] Then, the location of the fill region within the sample wafer is determined.

[0055] Next, the spectrum signals of the multiple filling areas of the sample wafer are collected. Specifically, the spectrum signals can be obtained by using the same method as step S1.

[0056] In this embodiment, spectral signals of multiple filling areas are collected, so multiple spectral signals are obtained.

[0057] Then, the optical parameters of the filling area of ​​the sample wafer are obtained by spectral fitting.

[0058] In this embodiment, the obtained multiple spectral signals are fitted to obtain multiple optical parameters. The optical parameter can be a phase difference or a refractive index. And because the voids in the filling area are not the same, and some of the filling areas do not have voids, the obtained multiple optical parameters are not the same, such as the refractive index of silicon oxide containing voids of different sizes and the refractive index of silicon oxide without voids. Since the refractive index of silicon oxide (1.462) is greater than the refractive index of voids (1.0002), the refractive indices corresponding to different void sizes are not the same, and the larger the void, the smaller the refractive index, and the refractive index of the filling area without voids is greater than the refractive index of the filling area containing voids.

[0059] Then, the void sizes or void ratios in a plurality of filling regions of the sample wafer are measured, and a calibration curve is drawn according to the void sizes or void ratios and corresponding optical parameters.

[0060] In this embodiment, the sample wafer needs to be sliced. Exemplarily, the sample wafer is sliced ​​in a direction perpendicular to the sample wafer to expose the cavity. Figure 4b As shown, the wafer to be tested 10 (here should be the sample wafer) is sliced ​​in a direction perpendicular to the substrate 11 to expose the longitudinal section of the cavity 14, and then a transmission electron microscope can be used to measure the area of ​​the exposed cavity. That is to say, in this embodiment, the cavity size refers to the longitudinal cross-sectional area of ​​the cavity in the direction perpendicular to the sample wafer. Preferably, it can be the largest longitudinal cross-sectional area in the direction perpendicular to the sample wafer, that is, the sample wafer is sliced ​​at the position where the cavity is the largest.

[0061] Different refractive indices correspond to different cavities, that is, to different cavity sizes. Therefore, a calibration curve can be drawn according to different cavity sizes and their corresponding refractive indices. Figure 5 is a schematic diagram of a calibration curve provided by an embodiment of the present invention, please refer to Figure 5 As shown, the calibration curve is a schematic diagram of the relationship between the refractive index and the cavity size. It should be noted that the schematic diagram in the present invention only shows the change trend between the two parameters. Figure 5 It can be seen from the figure that as the size of the cavity increases, the refractive index of the groove region of the sample wafer decreases.

[0062] Different phase differences also correspond to different holes, that is, to different hole sizes. Therefore, a calibration curve can be drawn according to different hole sizes and their corresponding phase differences. Figure 5 Similarly, as the size of the void increases, the phase difference of the filling area of ​​the sample wafer decreases.

[0063] It should be noted that if the calibration curve of refractive index and hole size is obtained, the refractive index of the filling area of ​​the wafer to be inspected needs to be obtained in step S1; if the calibration curve of phase difference and hole size is obtained, the phase difference of the filling area of ​​the wafer to be inspected needs to be obtained in step S1.

[0064] In this embodiment, the void ratios in the multiple filling regions of the sample wafer may also be measured, and the calibration curve may be drawn according to the void ratios and corresponding optical parameters. Figure 6 is a schematic diagram of a calibration curve provided by another embodiment of the present invention, please refer to Figure 6 As shown, the calibration curve is a schematic diagram of the relationship between the refractive index and the void ratio. Figure 6 It can be seen that as the void ratio increases, the refractive index of the filling area of ​​the sample wafer decreases.

[0065] In this embodiment, the optical parameters of the filled area of ​​the wafer to be inspected and the calibration curve are used to determine whether there are voids in the filled area of ​​the wafer to be inspected and obtain the size or void ratio of the voids. Then, the dielectric constant of the filled area of ​​the wafer to be inspected can also be obtained. Figure 7 is a schematic diagram of the relationship between dielectric constant and void ratio provided by an embodiment of the present invention, please refer to Figure 7 As shown, as the void ratio increases, the dielectric constant of the filling area decreases, and the dielectric constant of the filling area can be obtained according to the void ratio. Therefore, the void detection method provided by the present invention can not only detect whether there is a void and the size or void ratio of the void, but also obtain the dielectric constant of the filling area according to the void size or void ratio, that is, the present invention can not only detect the void but also the dielectric constant.

[0066] Accordingly, the present invention further provides a cavity detection device for detecting cavities, the cavity detection device comprising:

[0067] A light source, wherein the linearly polarized light provided by the light source is incident on the surface of the filling area of ​​the wafer to be inspected at a non-perpendicular angle;

[0068] A spectrometer, the spectrometer receives reflected light and refracted light from the surface of the filling area of ​​the wafer to be inspected to obtain a spectral signal;

[0069] A processing system is provided, wherein the processing system obtains optical parameters of the filling area of ​​the wafer to be inspected according to the spectral signal, and determines whether there are voids in the filling area of ​​the wafer to be inspected according to the optical parameters and a calibration curve, and obtains the size or void ratio of the voids.

[0070] The processing system may also obtain the dielectric constant of the filling area of ​​the wafer to be inspected according to the size of the void or the void ratio.

[0071] In summary, in the void detection method and detection device provided by the present invention, the spectral signal of the filling area of ​​the wafer to be detected is first collected to obtain the optical parameters of the filling area of ​​the wafer to be detected, and the presence of voids in the filling area of ​​the wafer to be detected and the size or void ratio of the voids are determined based on the optical parameters and the calibration curve. The void detection method provided by the present invention can quickly determine whether there are voids in the filling area of ​​the wafer to be detected by comparing the optical parameters of the filling area of ​​the wafer to be detected with the calibration curve, and can also obtain the void size or void ratio based on the calibration curve, which greatly improves the void detection speed, saves detection time, and does not require destructive detection of the wafer to be detected.

[0072] 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 void detection method, characterized in that: The following steps are involved: Collecting spectral signals of the filling area of ​​the wafer to be inspected to obtain optical parameters of the filling area of ​​the wafer to be inspected; and It is determined whether there is a void in the filling area of ​​the wafer to be inspected according to the optical parameters and the calibration curve, and the size or void ratio of the void is obtained.

2. The void detection method according to claim 1, characterized in that: Methods for drawing calibration curves include: collecting spectral signals of a plurality of filling areas of a sample wafer; Obtaining optical parameters of the filling area of ​​the sample wafer by spectral fitting; measuring void sizes or void ratios within a plurality of filling regions of the sample wafer; and, The calibration curve is drawn according to the void size or void ratio and the corresponding optical parameters.

3. The void detection method according to claim 1, characterized in that: The optical parameters include a refractive index of the filling region or a phase difference in a spectral signal.

4. The void detection method according to claim 1, characterized in that: The film layer filled in the filling area includes a metal layer, an oxide layer, a nitride layer, an amorphous silicon layer, a polysilicon layer, a photoresist layer, a low-K material layer, a silicon oxynitride layer, a silicon carbide nitride layer, an anti-reflection layer or a multi-layer film reflective polarizer.

5. The cavity detection method according to claim 4, characterized in that: The filling region includes a trench region, and the trench region includes a substrate, an isolation trench formed in the substrate, and an insulating material filled in the isolation trench.

6. The void detection method according to claim 4, characterized in that: The cavity is formed in the isolation trench.

7. The void detection method according to claim 2, characterized in that: In collecting spectral signals of multiple filling areas of a sample wafer, the filling areas are multiple filling areas of the same sample wafer, or / and, the filling area is one filling area of ​​multiple sample wafers.

8. The void detection method according to claim 2, characterized in that: The method for measuring the void size or void ratio in multiple filling regions of the sample wafer includes: slicing the sample wafer in a direction perpendicular to the sample wafer to expose the voids in the filling regions, and measuring the size or void ratio of the exposed voids using a transmission electron microscope.

9. The cavity detection method according to any one of claims 1 to 5, characterized in that: After obtaining the light parameters or the size of the void or the void ratio, the method further includes: obtaining the dielectric constant of the filling area of ​​the wafer to be inspected.

10. A cavity detection device, characterized in that: include: A light source, wherein the linearly polarized light provided by the light source is incident on the surface of the filling area of ​​the wafer to be inspected at a non-perpendicular angle; A spectrometer, the spectrometer receives reflected light and refracted light from the surface of the filling area of ​​the wafer to be inspected to obtain a spectral signal; as well as, A processing system is provided, wherein the processing system obtains optical parameters of the filling area of ​​the wafer to be inspected according to the spectral signal, and determines whether there are voids in the filling area of ​​the wafer to be inspected according to the optical parameters and a calibration curve, and obtains the size or void ratio of the voids.

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