Non-contact test method for notch contour of polished silicon wafer

Abstract

The invention provides a non-contact test method for a notch outline of a polished silicon wafer. The non-contact test method comprises the following steps: providing a polished silicon wafer with a notch; depositing a layer of film at the gap position of the polished silicon wafer to change the glossiness and roughness of the surface of the gap; using a non-contact testing device to obtain surface contour data of the gap position after the film is deposited; and performing data analysis on the obtained surface contour data. The invention provides a non-contact testing method, which not only can effectively solve the problem that the notch outline of the polished silicon wafer cannot be represented in a non-destructive form in the prior art, improves the silicon wafer detection precision and the product quality control level, but also improves the surface state of the notch by depositing the film, thereby improving the quality of the silicon wafer. The laser signal of the high-glossiness area is effectively acquired, and the accuracy of optical test data is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of wafer detection, and in particular relates to a non-contact testing method for a notch profile of a polished silicon wafer. Background Art

[0002] The edge profile test equipment currently on the market is difficult to accurately characterize the notch profile of polished silicon wafers. The main reasons include the following two points:

[0003] 1. Uniqueness of the Notch position: Traditional CCD testing methods are difficult to obtain contour data of the Notch area. They can only obtain morphological information and cannot further analyze the characteristics of the Notch contour.

[0004] 2. Surface optical properties: The surface roughness of the Notch area after polishing is extremely low and the glossiness is high. The laser signal is reflected multiple times in this area, making data collection difficult.

[0005] Existing solutions (such as destructive testing methods such as light sectioning or laser microscopy) cannot accurately measure the notch contour. This technical limitation may lead to the failure to detect production process defects in a timely manner, affecting product quality and reducing the yield rate. In addition, existing testing solutions are mostly based on non-polished wafers or destructive testing. There is no effective non-contact, non-destructive technology for characterizing the contour of the notch area of ​​the final polished wafer.

[0006] Therefore, how to accurately measure the notch profile of polished silicon wafers in a non-destructive way and improve the inspection accuracy and product quality control level of polished silicon wafers is a technical problem that needs to be solved urgently. Summary of the invention

[0007] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a non-contact testing method for the notch profile of a polished silicon wafer. The present invention provides a non-contact testing method, which can not only effectively solve the problem that the prior art cannot characterize the notch profile of a polished silicon wafer in a non-destructive manner, thereby improving the silicon wafer detection accuracy and product quality control level, but also improve the surface state of the notch by depositing a thin film, thereby achieving effective collection of laser signals in high gloss areas, and ensuring the accuracy of optical test data.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a non-contact testing method for a notch profile of a polished silicon wafer, the non-contact testing method comprising the following steps:

[0010] A polished silicon wafer having a notch is provided.

[0011] Deposit a thin film at the notch position of the polished silicon wafer to change the gloss and roughness of the notch surface.

[0012] Use a non-contact testing device to obtain the surface profile data of the notch position after depositing the thin film.

[0013] Perform data analysis on the obtained surface profile data.

[0014] The present invention provides a non-contact testing method, which can not only effectively solve the problem that the prior art cannot characterize the notch profile of the polished silicon wafer in a non-destructive manner, improve the silicon wafer detection accuracy and product quality control level, but also improve the surface state of the notch by depositing a thin film, realize effective acquisition of laser signals in high-gloss areas, and ensure the accuracy of optical test data.

[0015] Preferably, the material of the thin film includes metal oxides.

[0016] In the present invention, a thin film with a material of metal oxides can effectively change the surface optical properties of the notch and ensure the accuracy of optical test data.

[0017] Preferably, the metal oxide includes titanium dioxide.

[0018] Preferably, the thickness of the thin film ≤ 1μm, for example, it can be 1μm, 0.8μm, 0.5μm, 0.2μm, 0.1μm, 0.05μm or 0.01μm, etc.

[0019] Preferably, after the thin film is deposited, the roughness of the notch surface satisfies the following conditions:

[0020] 2nm < Sa < 50nm, for example, it can be 5nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm or 50nm, etc.

[0021] It should be noted that "Sa" is the symbol of Arithmetic Mean Height. It is a surface roughness parameter based on the area and is used to describe the change of surface height. Specifically, Sa is the value obtained by arithmetic averaging the absolute values of the surface height deviations within a given measurement area, and this value can quantitatively reflect the roughness of the surface.

[0022] It should be noted that the detection result of the roughness of the notch surface after the thin film is deposited depends on the capabilities of the detection equipment.

[0023] Preferably, after the thin film is deposited, the gloss of the notch surface ≤ 80%, for example, it can be 80%, 70%, 60%, 50%, 40% or 30%, etc.

[0024] In the present invention, the glossiness of the notch surface is ≤80%, which has the following advantages: 1) reducing light reflection interference; 2) reducing detection errors.

[0025] It should be noted that the glossiness of the notch surface can be measured using a gloss meter.

[0026] Preferably, the non-contact testing device comprises a load port, an aligner, a manipulator, a metrology component and a data analysis component.

[0027] Among them, the load port is used to carry and transmit the polished silicon wafer, so as to send the polished silicon wafer into the non-contact testing device; the aligner is used to calibrate the position and adjust the direction of the polished silicon wafer, so that the polished silicon wafer is aligned to a preset position and direction; the manipulator is used to carry and operate the polished silicon wafer; the metering component is used to obtain the surface profile data of the polished silicon wafer; and the data analysis component is used to receive and process the surface profile data obtained by the metering component.

[0028] Preferably, the metering component includes a light source irradiation device and an image acquisition device; wherein the light source irradiation device includes three groups of laser probes, which are respectively arranged on the upper side, the lower side and the tangential side of the notch position of the polished silicon wafer, for irradiating the notch with a light beam; the image acquisition device is a charge coupled device camera, which is used to collect the laser signal of the notch to obtain the surface profile data of the notch.

[0029] In the present invention, the laser probe adopts a non-contact measurement method, which does not damage the surface of the silicon wafer, avoiding problems such as silicon wafer surface contamination or scratches caused by contact. In addition, laser probes are respectively arranged on the upper side, lower side and tangential side of the notch position of the polished silicon wafer, so that the notch profile information can be accurately obtained.

[0030] It should be noted that a charge-coupled device camera (CCD camera) is a semiconductor device that can convert optical signals into electrical signals. In a CCD camera, when light passes through the lens and shines onto the CCD chip, photons are absorbed by the photodiodes in the chip. The energy of the photons causes the photodiodes to generate electron-hole pairs, which are collected and stored in the pixel units of the CCD chip. The CCD chip controls the transfer of charges through a series of electrodes. After the exposure is completed, these charges are transferred out of the chip in a certain order (usually row by row or column by column). This process is like an "electron queue", and eventually an electrical signal corresponding to the light intensity is formed at the output end of the chip. After subsequent amplification, filtering and other processing, these electrical signals can be converted into digital image signals for storage or further analysis and processing.

[0031] Preferably, the notch is a U-shaped notch or a V-shaped notch.

[0032] Preferably, the surface profile data of the U-shaped notch includes:

[0033] The thickness of the silicon wafer after polishing; the depth of the notch; the length of the notch; the double-bevel chamfer radius of the notch; the distance between the two sides of the edge of the notch and the plane where the front and back sides of the silicon wafer after polishing are located; the angles formed by the two side walls of the notch and the plane where the front and back sides of the silicon wafer after polishing are located.

[0034] Among them, the depth of the notch refers to the vertical distance from the edge of the notch to the bottom of the notch; the length of the notch refers to the extension length of the notch along the edge of the silicon wafer; the double-bevel chamfer radius of the notch refers to the radius of the arc chamfer where the two side bevels of the notch transition with the end face. From the cross-section, it looks like an arc is used to connect the oblique line and the end line of the notch.

[0035] Preferably, the surface profile data of the V-shaped notch includes:

[0036] The thickness of the silicon wafer after polishing; the depth of the notch; the length of the notch; the chamfer radius of the notch; the distance between the edge of the notch and the plane where the front and back sides of the silicon wafer are located after polishing; the angles formed by the two side walls of the notch and the plane where the front and back sides of the silicon wafer are located after polishing.

[0037] Among them, the chamfer radius of the notch refers to the chamfer radius of the arc formed at the edge of the notch, which is like "rounding" the right-angle edge.

[0038] Preferably, before the non-contact testing device acquires the surface profile data of the notch position after the thin film is deposited, a standard silicon wafer is first used to calibrate the device.

[0039] In the present invention, the purpose of performing equipment calibration is to improve the test accuracy of surface profile data.

[0040] Preferably, the data analysis method comprises the SEMI-73 analysis method.

[0041] It should be noted that the SEMI-73 analysis method (SEMI refers to the International Semiconductor Industry Association) is a standard method used in the semiconductor industry for silicon wafer testing and quality assessment. It mainly focuses on the analysis of the geometry, dimensional accuracy, and surface characteristics of silicon wafers, and is an important means to ensure that the quality of silicon wafers meets the strict requirements of semiconductor manufacturing. The SEMI-73 analysis method is a key link in silicon wafer quality control. Through strict testing and analysis, silicon wafers that do not meet quality standards can be screened out to prevent them from entering the subsequent process links of chip manufacturing, thereby reducing chip defects and yield reductions caused by silicon wafer quality problems.

[0042] Preferably, the non-contact testing method comprises the following steps:

[0043] (1) Providing a polished silicon wafer with a notch, depositing a metal oxide film with a thickness of ≤1 μm at the notch position of the polished silicon wafer, so that the glossiness of the notch surface is ≤80% and the roughness is: 2 nm <Sa<10nm;

[0044] (2) A standard silicon wafer is used to calibrate the non-contact testing device. After the calibration, the standard silicon wafer is removed and the polished silicon wafer with the notch is placed at a set detection position of the non-contact testing device. Three sets of laser probes are used to irradiate the upper side, the lower side and the tangential side of the notch respectively. Then, a charge-coupled device camera is used to obtain surface profile data of the notch position after the thin film is deposited. The profile image is analyzed by a data analysis component. The data analysis method is the SEMI-73 analysis method.

[0045] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The present invention provides a non-contact testing method, which can not only effectively solve the problem that the prior art cannot characterize the notch profile of the polished silicon wafer in a non-destructive manner, thereby improving the silicon wafer detection accuracy and product quality control level, but also improve the surface state of the notch by depositing a thin film, thereby achieving effective collection of laser signals in high gloss areas and ensuring the accuracy of optical test data.

[0048] The non-contact testing method provided by the invention can be used for accurate characterization of the profile of the notch in the polished large silicon wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a schematic diagram of the non-contact testing device provided by the present invention.

[0050] Figure 2 This is a structural diagram of a notch profile testing unit for a polished silicon wafer provided by the present invention.

[0051] Figure 3 A schematic diagram of the notch profile test of a polished silicon wafer provided by the present invention.

[0052] Figure 4 A schematic diagram of a notch after depositing a titanium dioxide film provided by an embodiment of the present invention.

[0053] Figure 5 A notch profile morphology diagram of a polished silicon wafer provided in one embodiment of the present invention.

[0054] Figure 6 A schematic diagram of notch profile detection of a polished silicon wafer provided in one embodiment of the present invention.

[0055] Figure 7 A schematic diagram of notch profile detection of a polished silicon wafer provided in another embodiment of the present invention.

[0056] Figure 8 A process flow chart of a non-contact testing method provided by an embodiment of the present invention is shown.

[0057] Among them, 1-load port; 2-aligner; 3-manipulator; 4-metering component; 5-data analysis component; 6-laser probe; 7-charged coupled device camera; t-thickness of the polished silicon wafer; A-depth of the notch; C-length of the notch; R1-upper chamfer radius of the notch; R2-lower chamfer radius of the notch; R3-chamfer radius of the notch; B1-distance between one side of the edge of the notch and the plane where the front side of the polished silicon wafer is located; B2-distance between the other side of the edge of the notch and the plane where the back side of the polished silicon wafer is located Distance; B3-the distance between the edge of the notch and the plane where the front side of the silicon wafer is located after polishing; B4-the distance between the edge of the notch and the plane where the front side of the silicon wafer is located after polishing; α1-the angles formed by one side wall of the notch and the plane where the front side of the silicon wafer is located after polishing; α2-the angles formed by the other side wall of the notch and the plane where the back side of the silicon wafer is located after polishing; β1-the angles formed by the two side walls of the notch and the plane where the front side of the silicon wafer is located after polishing; β2-the angles formed by the two side walls of the notch and the plane where the front side of the silicon wafer is located after polishing. DETAILED DESCRIPTION

[0058] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0059] It should be noted that in the following embodiments, the schematic diagram of the non-contact testing device used is as follows: Figure 1 As shown, the non-contact testing device comprises a load port 1, an aligner 2, a manipulator 3, a metering component 4 and a data analysis component 5;

[0060] Among them, the load port 1 is used to carry and transport the polished silicon wafer, so as to send the polished silicon wafer into the non-contact testing device; the aligner 2 is used to calibrate the position and adjust the direction of the polished silicon wafer, so that the polished silicon wafer is aligned to a preset position and direction; the manipulator 3 is used to carry and operate the polished silicon wafer; the metering component 4 is used to obtain the surface profile data of the polished silicon wafer; the data analysis component 5 is used to receive and process the surface profile data obtained by the metering component.

[0061] Among them, the metering component 4 includes a light source irradiation device and an image acquisition device; the light source irradiation device includes three groups of laser probes 6, which are respectively arranged on the upper side, lower side and tangential side of the notch position of the polished silicon wafer, and are used to irradiate the notch with light beams, as Figure 2 shown; the image acquisition device is a charge-coupled device camera 7, which is used to collect the laser signals of the notch to obtain the surface profile data of the notch, as Figure 3 shown.

[0062] Embodiment 1

[0063] This embodiment provides a non-contact testing method for the notch profile of a polished silicon wafer. The process flow chart is as Figure 8 shown. The non-contact testing method includes the following steps:

[0064] (1) Provide a polished silicon wafer with a notch, and deposit a titanium dioxide thin film with a thickness of 1 μm at the notch position of the polished silicon wafer, as Figure 4 shown, so that the glossiness of the notch surface ≤ 80%, and the roughness is: 2 nm < Sa < 10 nm; among them, the notch is a U-shaped notch.

[0065] (2) Use a standard silicon wafer to calibrate the non-contact testing device. After the calibration is completed, remove the standard silicon wafer, and place the polished silicon wafer with the notch at the set detection position of the non-contact testing device. Use three groups of laser probes to irradiate the upper side, lower side and tangential side of the notch with light beams respectively, and then use a charge-coupled device camera to obtain the surface profile data of the notch position after depositing the thin film, and perform data analysis on the profile image (as Figure 5 shown) through the data analysis component. The data analysis method is the SEMI-73 analysis method;

[0066] Refer to Figure 6It can be known that the surface profile data includes the thickness t of the polished silicon wafer; the depth A of the notch; the length C of the notch; the chamfer radius R1 of the upper inclined surface of the notch; the chamfer radius R2 of the lower inclined surface of the notch; the distance B1 between one side of the notch edge and the plane where the front surface of the polished silicon wafer is located; the distance B2 between the other side of the notch edge and the plane where the back surface of the polished silicon wafer is located; the angle α1 formed between one side wall of the notch and the plane where the front surface of the polished silicon wafer is located; the angle α2 formed between the other side wall of the notch and the plane where the back surface of the polished silicon wafer is located.

[0067] Example 2

[0068] This embodiment provides a non-contact testing method for the notch profile of a polished silicon wafer. The non-contact testing method includes the following steps:

[0069] (1) Provide a polished silicon wafer with a notch, deposit a titanium dioxide thin film with a thickness of 1 μm at the notch position of the polished silicon wafer, so that the glossiness of the notch surface ≤ 80%, and the roughness is: 2 nm < Sa < 10 nm; wherein, the notch is a V-shaped notch.

[0070] (2) Use a standard silicon wafer to calibrate the non-contact testing device. After the calibration is completed, remove the standard silicon wafer, and place the polished silicon wafer with a notch at the set detection position of the non-contact testing device. Use three groups of laser probes to irradiate the upper side, lower side, and tangential side of the notch respectively, and then use a charge-coupled device camera to obtain the surface profile data of the notch position after depositing the thin film, and perform data analysis on the profile image through a data analysis component. The method of data analysis is the SEMI-73 analysis method;

[0071] Refer to Figure 7 It can be known that the surface profile data includes the thickness t of the polished silicon wafer; the depth A of the notch; the length C of the notch; the chamfer radius R3 of the notch; the distance B3 between the notch edge and the plane where the front surface of the polished silicon wafer is located; the distance B4 between the notch edge and the plane where the front surface of the polished silicon wafer is located; the angle β1 formed between the two side walls of the notch and the plane where the front surface of the polished silicon wafer is located; the angle β2 formed between the two side walls of the notch and the plane where the front surface of the polished silicon wafer is located.

[0072] Example 3

[0073] The difference between this embodiment and Embodiment 1 is that the thickness of the titanium dioxide thin film is 1.5 μm.

[0074] The remaining non-contact testing methods and parameters are the same as those in Embodiment 1.

[0075] Comparative Example 1

[0076] The difference between this comparative example and Example 1 is that the titanium dioxide film is not deposited in step (1).

[0077] The remaining non-contact test methods and parameters remain the same as those in Example 1.

[0078] In summary, the purpose of the present invention is to improve the optical properties of the notch position by improving the surface gloss and roughness, so that the surface profile can be characterized in a non-contact and non-destructive manner.

[0079] From the comparison between Example 1 and Example 3, it can be seen that if the titanium dioxide film is too thick, it will cause waste of materials and prolong processing time, and increase costs while ensuring uniformity. If the titanium dioxide film is not deposited, the laser will be internally reflected multiple times at the notch position without surface improvement, so that the surface profile data information of the notch position cannot be accurately obtained, and thus characterization cannot be performed.

[0080] The applicant declares that the present invention illustrates the process method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned process steps, that is, it does not mean that the present invention must rely on the above-mentioned process steps to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A non-contact testing method for the notch profile of a polished silicon wafer, characterized in that: The non-contact testing method comprises the following steps: Providing a polished silicon wafer having a notch; Depositing a thin film at the notch position of the polished silicon wafer to change the glossiness and roughness of the notch surface; Using a non-contact testing device to obtain surface profile data of the notch position after the thin film is deposited; The obtained surface profile data are analyzed.

2. The non-contact testing method according to claim 1, characterized in that: The material of the film includes metal oxide; Preferably, the metal oxide comprises titanium dioxide; Preferably, the thickness of the film is ≤1 μm.

3. The non-contact testing method according to claim 1 or 2, characterized in that: After the film is deposited, the roughness of the notch surface satisfies the following conditions: 2nm <Sa<50nm。 4. The non-contact testing method according to any one of claims 1 to 3, characterized in that: After the film is deposited, the glossiness of the notch surface is ≤80%.

5. The non-contact testing method according to any one of claims 1 to 4, characterized in that: The non-contact testing device comprises a load port, an aligner, a manipulator, a metering component and a data analysis component; The load port is used to carry and transfer the polished silicon wafer, so as to send the polished silicon wafer into the non-contact testing device; the aligner is used to calibrate the position and adjust the direction of the polished silicon wafer, so that the polished silicon wafer is aligned to a preset position and direction; the manipulator is used to carry and operate the polished silicon wafer; the metering component is used to obtain the surface profile data of the polished silicon wafer; the data analysis component is used to receive and process the surface profile data obtained by the metering component; Preferably, the metering component includes a light source irradiation device and an image acquisition device; wherein the light source irradiation device includes three groups of laser probes, which are respectively arranged on the upper side, the lower side and the tangential side of the notch position of the polished silicon wafer, for irradiating the notch with a light beam; the image acquisition device is a charge coupled device camera, which is used to collect the laser signal of the notch to obtain the surface profile data of the notch.

6. The non-contact testing method according to any one of claims 1 to 5, characterized in that: The notch is a U-shaped notch or a V-shaped notch; Preferably, the surface profile data of the U-shaped notch includes: The thickness of the silicon wafer after polishing; the depth of the notch; the length of the notch; the radius of the double bevel chamfer of the notch; the distance between the two sides of the edge of the notch and the plane where the front and back sides of the silicon wafer after polishing are located; the angles formed by the two side walls of the notch and the plane where the front and back sides of the silicon wafer after polishing are located; Preferably, the surface profile data of the V-shaped notch includes: The thickness of the silicon wafer after polishing; the depth of the notch; the length of the notch; the chamfer radius of the notch; the distance between the edge of the notch and the plane where the front and back sides of the silicon wafer are located after polishing; the angles formed by the two side walls of the notch and the plane where the front and back sides of the silicon wafer are located after polishing.

7. The non-contact testing method according to any one of claims 1 to 6, characterized in that: Before the non-contact testing device acquires the surface profile data of the notch position after the thin film is deposited, a standard silicon wafer is used to calibrate the device.

8. The non-contact testing method according to any one of claims 1 to 7, characterized in that: The data analysis method includes the SEMI-73 analysis method.

9. The non-contact testing method according to any one of claims 1 to 8, characterized in that: The non-contact testing method comprises the following steps: (1) Providing a polished silicon wafer with a notch, depositing a metal oxide film with a thickness of ≤1 μm at the notch position of the polished silicon wafer, so that the glossiness of the notch surface is ≤80% and the roughness is: 2 nm <Sa<10nm; (2) A standard silicon wafer is used to calibrate the non-contact testing device. After the calibration, the standard silicon wafer is removed and the polished silicon wafer with the notch is placed at a set detection position of the non-contact testing device. Three sets of laser probes are used to irradiate the upper side, the lower side and the tangential side of the notch respectively. Then, a charge-coupled device camera is used to obtain surface profile data of the notch position after the thin film is deposited. The profile image is analyzed by a data analysis component. The data analysis method is the SEMI-73 analysis method.

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